QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.1

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

AGREEMENT AND PLAN OF REDEMPTION AND MERGER

by and among

MarkWest Hydrocarbon, Inc.

MarkWest Energy Partners, L.P.

and

MWEP, L.L.C.

Dated as of September 5, 2007

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

TABLE OF CONTENTS

ARTICLE I
CERTAIN DEFINITIONS
Section 1.1
 
Certain Definitions
 
1
ARTICLE II
THE REDEMPTION AND MERGER; EFFECTS OF THE MERGER
Section 2.1
 
The Redemption
 
9 Section 2.2   The Merger   9 Section 2.3   Closing   9
ARTICLE III
REDEMPTION AND MERGER CONSIDERATION; EXCHANGE PROCEDURES
Section 3.1
 
Redemption and Merger Consideration
 
10 Section 3.2   Election Procedures   10 Section 3.3   Appraisal Rights   13
Section 3.4   Rights As Stockholders; Stock Transfers   13 Section 3.5  
Exchange of Certificates   14 Section 3.6   Anti-Dilution Provisions   16
Section 3.7   Options and Restricted Shares   16
ARTICLE IV
ACTIONS PENDING MERGER
Section 4.1
 
Ordinary Course
 
17 Section 4.2   Capital Stock   17 Section 4.3   Dividends, Distributions   17
Section 4.4   Compensation; Employment Agreements   18 Section 4.5   Benefit
Plans   18 Section 4.6   Acquisitions and Dispositions   18 Section 4.7  
Amendments   18 Section 4.8   Accounting Methods   18 Section 4.9   Insurance  
19 Section 4.10   Taxes   19 Section 4.11   Debt, Capital Expenditures and the
Like   19 Section 4.12   No Dissolution   19 Section 4.13   Adverse Actions   19
Section 4.14   Agreements   19
ARTICLE V
REPRESENTATIONS AND WARRANTIES
Section 5.1
 
Disclosure Schedule
 
19 Section 5.2   Standard   20 Section 5.3   Representations and Warranties   20

i

--------------------------------------------------------------------------------

ARTICLE VI
COVENANTS
Section 6.1
 
Best Efforts
 
27 Section 6.2   Equityholder Approvals   27 Section 6.3   Registration
Statement   28 Section 6.4   Press Releases   29 Section 6.5   Access;
Information   29 Section 6.6   Acquisition Proposals   29 Section 6.7  
Affiliate Arrangements   31 Section 6.8   Takeover Laws   31 Section 6.9   No
Rights Triggered   32 Section 6.10   Common Units Listed   32 Section 6.11  
Third Party Approvals   32 Section 6.12   Indemnification; Directors' and
Officers' Insurance   32 Section 6.13   Comfort Letters   34 Section 6.14  
Benefit Plans   35 Section 6.15   Notification of Certain Matters   35 Section
6.16   Rule 16b-3   35 Section 6.17   Amended and Restated Partnership Agreement
  35 Section 6.18   Board Membership   35
ARTICLE VII
CONDITIONS TO CONSUMMATION OF THE REDEMPTION AND MERGER
Section 7.1
 
Stockholder Vote
 
35 Section 7.2   Governmental Approvals   35 Section 7.3   No Injunction   36
Section 7.4   Representations, Warranties and Covenants of Energy Partners   36
Section 7.5   Representations, Warranties and Covenants of Hydrocarbon   36
Section 7.6   Effective Registration Statement   36 Section 7.7   Opinion of
Vinson & Elkins L.L.P. or Other Counsel.   36 Section 7.8   Opinion of Hogan &
Hartson L.L.P. or Other Counsel   37 Section 7.9   NYSE Listing   37 Section
7.10   Amended and Restated Partnership Agreement   37 Section 7.11   Dissenting
Holders   37 Section 7.12   Resignation of the Hydrocarbon Board   37 Section
7.13   Restructuring Transactions   37 Section 7.14   Valuation Appraisal   37
Section 7.15   Changes in Tax Law   38 Section 7.16   Redemption   38
ARTICLE VIII
TERMINATION
Section 8.1
 
Termination
 
38 Section 8.2   Effect of Termination   40
ARTICLE IX
MISCELLANEOUS
Section 9.1
 
Fees and Expenses
 
40          

ii

--------------------------------------------------------------------------------

Section 9.2   Waiver; Amendment   42 Section 9.3   Counterparts   42 Section 9.4
  Governing Law   42 Section 9.5   Confidentiality   42 Section 9.6   Notices  
43 Section 9.7   Entire Understanding; No Third Party Beneficiaries   44 Section
9.8   Severability   44 Section 9.9   Headings   44 Section 9.10   Jurisdiction
  44 Section 9.11   Waiver of Jury Trial   44 Section 9.12   Specific
Performance   44 Section 9.13   Survival   45 Section 9.14   No Act or Failure
to Act   45

iii

--------------------------------------------------------------------------------

ANNEXES

Annex A   Amended and Restated Partnership Agreement Annex B   Redemption
Charter Amendment Annex C   Certificate of Incorporation Annex D   Bylaws of
Surviving Entity Annex E   Confidentiality Agreement

iv

--------------------------------------------------------------------------------

DISCLOSURE SCHEDULES

Schedule 4.2   (Hydrocarbon only) Capital stock; issuance of additional shares
Schedule 4.4   (Hydrocarbon only) Compensation; Employment Agreements Schedule
4.5   (Hydrocarbon only) Benefit Plans Schedule 4.11   (Hydrocarbon only) Debt
and Capital Expenditures Schedule 5.3(b)   Shares; Shares/Units reserved for
issuance; stock options Schedule 5.3(c)   Subsidiaries Schedule 5.3(h)  
Litigation Schedule 5.3(i)   Compliance with laws (exception for no Material
Adverse Effect) Schedule 5.3(l)(i)   Compensation and Benefit Plans Schedule
5.3(l)(vii)   Golden parachutes, etc. Schedule 5.3(m)   Collective bargaining
agreement Schedule 5.3(n)   Environmental Matters Schedule 5.3(p)   Regulatory
approval Schedule 5.3(t)   Intellectual property

v

--------------------------------------------------------------------------------

AGREEMENT AND PLAN OF REDEMPTION AND MERGER

        This AGREEMENT AND PLAN OF REDEMPTION AND MERGER, dated as of
September 5, 2007 (this "Agreement"), is entered into by and among MARKWEST
HYDROCARBON, INC., a Delaware corporation ("Hydrocarbon"), MARKWEST ENERGY
PARTNERS, L.P., a Delaware limited partnership ("Energy Partners"), and MWEP,
L.L.C., a Delaware limited liability company ("MergerCo") and a wholly-owned
subsidiary of Energy Partners.

WITNESSETH:

        WHEREAS, the Board of Directors of Hydrocarbon (the "Hydrocarbon
Board"), upon the recommendation of the Deal Committee (as defined herein), and
the Board of Directors of MarkWest Energy GP, L.L.C., the general partner (the
"General Partner") of Energy Partners, upon the recommendation of the Conflicts
Committee (as defined herein), have determined that it is in the best interests
of Hydrocarbon and its stockholders, and Energy Partners and its limited
partners, respectively, to consummate the business combination provided for
herein pursuant to which (i) Hydrocarbon will, subject to the terms and
conditions set forth herein, redeem in the Redemption (as defined herein) a
portion of its outstanding shares of Hydrocarbon Common Stock (as defined
herein) and then (ii) MergerCo will, subject to the terms and conditions set
forth herein, merge (the "Merger") with and into Hydrocarbon, with Hydrocarbon
surviving, such that following the Redemption and Merger, Hydrocarbon will be a
direct, wholly owned subsidiary of Energy Partners;

        WHEREAS, the Fox Support Agreement (as defined herein), the Exchange
Agreement (as defined herein) and the Class B Membership Interest Contribution
Agreement (as defined herein) have been entered into simultaneously with the
execution of this Agreement; and

        WHEREAS, the parties desire to make certain representations, warranties
and agreements in connection with the Redemption and Merger and also to
prescribe certain conditions to the Redemption and Merger.

        NOW, THEREFORE, in consideration of the mutual covenants,
representations, warranties and agreements contained herein, and intending to be
legally bound hereby, the parties hereto agree as follows:

ARTICLE I

CERTAIN DEFINITIONS

        Section 1.1    Certain Definitions.    As used in this Agreement, the
following terms shall have the meanings set forth below:

        "Acquisition Proposal" means: any proposal or offer from or by any
Person other than Energy Partners and MergerCo relating to (i) any direct or
indirect acquisition of (A) all or substantially all of the assets of
Hydrocarbon and its Subsidiaries, taken as a whole, (B) more than 20% of the
outstanding equity securities of Hydrocarbon or (C) a business or businesses
that constitute more than 20% of the cash flow, net revenues, net income or
assets of Hydrocarbon and its Subsidiaries, taken as a whole; (ii) any tender
offer or exchange offer, as defined pursuant to the Exchange Act, that, if
consummated, would result in any Person beneficially owning more than 20% of the
outstanding equity securities of Hydrocarbon; or (iii) any merger,
consolidation, business combination, recapitalization, liquidation, dissolution
or similar transaction involving Hydrocarbon, other than the Redemption and
Merger, pursuant to which the stockholders of Hydrocarbon prior to consummation
of such transaction would hold less than 80% of the outstanding shares or equity
interests of the surviving or resulting Person or parent thereof.

1

--------------------------------------------------------------------------------

        "Affiliate" has the meaning set forth in Rule 405 of the rules and
regulations of the Securities Act, unless otherwise expressly stated herein.

        "Aggregate Consideration" shall mean the sum of (x) the Total Stock
Consideration and (y) the Total Cash Amount.

        "Agreement" shall have the meaning set forth in the introductory
paragraph to this Agreement.

        "Amended and Restated Partnership Agreement" shall mean the Third
Amended and Restated Agreement of Limited Partnership substantially in the form
attached hereto as Annex A.

        "Appraisal Shares" shall have the meaning set forth in Section 3.3.

        "Business Day" shall mean any day which is not a Saturday, Sunday or
other day on which banks are authorized or required to be closed in the City of
New York.

        "Cash Designated Shares" shall have the meaning set forth in
Section 3.2(e)(ii)(B).

        "Cash Election Shares" shall have the meaning set forth in
Section 3.2(b).

        "Certificate" shall have the meaning set forth in Section 3.1(f).

        "Certificate of Merger" shall have the meaning set forth in
Section 2.2(b).

        "Change in U.S. Federal Tax Law" shall have the meaning set forth in
Section 7.15(b).

        "Claim" shall have the meaning set forth in Section 6.12(a).

        "Class A Units" shall mean the Class A units representing limited
partner interests of Energy Partners having the rights and obligations specified
with respect to such Class A Units in the Amended and Restated Partnership
Agreement.

        "Class B Membership Interest Contribution Agreement" shall mean the
Class B Membership Interest Contribution Agreement, dated the date hereof,
entered into among Energy Partners and the holders of Class B membership
interests in the General Partner named therein.

        "Closing" shall have the meaning set forth in Section 2.3.

        "Closing Date" shall have the meaning set forth in Section 2.3.

        "Code" shall mean the Internal Revenue Code of 1986, as amended.

        "Common Units" shall mean the common units representing limited partner
interests of Energy Partners having the rights and obligations specified with
respect to Common Units in the Partnership Agreement and Amended and Restated
Partnership Agreement.

        "Compensation and Benefit Plans" shall have the meaning set forth in
Section 5.3(l)(i).

        "Confidentiality Agreement" shall mean a confidentiality agreement
substantially in the form attached hereto as Annex E (the "Confidentiality
Agreement").

        "Conflicts Committee" shall mean the Conflicts Committee of the Board of
Directors of the General Partner, consisting (as of the date hereof) of William
P. Nicoletti, Keith E. Bailey and Charles K. Dempster.

        "Deal Committee" shall mean the Deal Committee of the Hydrocarbon Board,
consisting (as of the date hereof) of Michael L. Beatty, Karen L. Rogers, Donald
D. Wolf and William F. Wallace.

        "Delaware LP Act" shall mean the Delaware Revised Uniform Limited
Partnership Act, as amended.

2

--------------------------------------------------------------------------------

        "Deemed Stock Amount" shall mean the Total Common Stock Amount;
provided, however, that regardless of the actual number of shares of Hydrocarbon
Common Stock outstanding immediately prior to the Redemption, which shall take
place immediately prior to the Effective Time, in no event shall the Deemed
Stock Amount exceed the sum of (i) 11,954,334 and (ii) the aggregate number of
shares of Hydrocarbon Common Stock, if any, issued by Hydrocarbon after the date
of this Agreement in accordance with Section 4.2.

        "DGCL" shall mean the Delaware General Corporation Law.

        "Disclosure Schedule" shall have the meaning set forth in Section 5.1.

        "Dissenting Holders" shall mean Hydrocarbon stockholders who have
demanded appraisal in accordance with the provisions of Section 262 of the DGCL
with regard to the Redemption Charter Amendment or the Merger concerning their
right to object to and dissent from the Redemption Charter Amendment or the
Merger.

        "Effective Time" shall have the meaning set forth in Section 2.2(b).

        "Election Deadline" shall have the meaning set forth in Section 3.2(b).

        "Election Form" shall have the meaning set forth in Section 3.2(a).

        "Election Form Record Date" shall have the meaning set forth in
Section 3.2(a).

        "Energy Partners" shall have the meaning set forth in the introductory
paragraph to this Agreement.

        "Energy Partners Change in Recommendation" shall have the meaning set
forth in Section 6.2.

        "Energy Partners' Disclosure Schedule" shall mean the Disclosure
Schedule delivered by Energy Partners pursuant to Section 5.1.

        "Energy Partners Meeting" shall have the meaning set forth in
Section 6.2.

        "Energy Partners Phantom Units" shall mean the phantom (notional) Common
Units granted under the MarkWest Energy Partners, L.P. Long-Term Incentive Plan.

        "Energy Partners Termination Fee" shall mean an amount equal to
$15 million in cash.

        "Energy Partners Recommendation" shall have the meaning set forth in
Section 6.2.

        "Energy Partners Unitholder Approval" shall have the meaning set forth
in Section 7.1.

        "Environmental Laws" shall mean all applicable local, state and federal
environmental, health and safety laws and regulations, including, without
limitation, the Resource Conservation and Recovery Act, the Comprehensive
Environmental Response, Compensation, and Liability Act, the Clean Water Act,
the Federal Clean Air Act, and the Occupational Safety and Health Act, each as
amended, regulations promulgated thereunder, and state counterparts.

        "ERISA" shall mean the Employee Retirement Income Security Act of 1974,
as amended.

        "ERISA Affiliate" shall have the meaning set forth in
Section 5.3(l)(iv).

        "Escrow Agent" shall mean Wells Fargo Bank, N.A. as escrow agent for the
benefit of Energy Partners for certain payments under Article IX.

        "Escrow Fund" shall have the meaning set forth in Section 9.1(g).

        "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations thereunder.

3

--------------------------------------------------------------------------------

        "Exchange Agreement" shall mean the Exchange Agreement among
Hydrocarbon, Energy Partners and the General Partner entered into simultaneously
with the execution of this Agreement.

        "Exchange Fund" shall have the meaning set forth in Section 3.5.

        "Exchange Ratio" shall mean the quotient, rounded to the nearest
ten-thousandth, obtained by dividing the Per Share Consideration by the Final
Energy Partners Unit Price.

        "Excluded Party" shall have the meaning set forth in Section 6.6(a).

        "Expenses" shall have the meaning set forth in Section 9.1(f).

        "Final Energy Partners Unit Price" shall mean the volume-weighted
average of the trading sale prices per Common Unit as reported on the NYSE
during the Valuation Period. The Final Energy Partner Unit Price shall be
calculated to the nearest one-hundredth of one cent.

        "Fox Support Agreement" shall mean the Voting Agreement among John M.
Fox and MWHC Holdings Inc. and Energy Partners, entered into simultaneously with
the execution of this Agreement.

        "General Partner" shall have the meaning set forth in the recitals to
this Agreement.

        "General Partner Units" shall mean the general partner units
representing a general partner interest in Energy Partners having the rights and
obligations specified with respect to General Partner Units in the Partnership
Agreement.

        "Governmental Authority" means any national, state, local, county,
parish or municipal government, domestic or foreign, any agency, board, bureau,
commission, court, tribunal, subdivision, department or other governmental or
regulatory authority or instrumentality, or any arbitrator in any case that has
jurisdiction over Hydrocarbon or Energy Partners, as the case may be, or any of
their respective properties or assets.

        "Hydrocarbon" shall have the meaning set forth in the introductory
paragraph of this Agreement.

        "Hydrocarbon Board" shall have the meaning set forth in the recitals to
this Agreement.

        "Hydrocarbon Bylaws" means the bylaws of Hydrocarbon.

        "Hydrocarbon Change in Recommendation" shall have the meaning set forth
in Section 6.6(c).

        "Hydrocarbon Charter" means the certificate of incorporation of
Hydrocarbon.

        "Hydrocarbon Common Stock" means the Common Stock, par value $.01 per
share, of Hydrocarbon.

        "Hydrocarbon Meeting" shall have the meaning set forth in Section 6.2.

        "Hydrocarbon Recommendation" shall have the meaning set forth in
Section 6.2.

        "Hydrocarbon Restricted Stock" shall mean shares of Hydrocarbon Common
Stock that have been granted to employees, directors and consultants of
Hydrocarbon or its Subsidiaries and as of the Redemption, which shall take place
immediately prior to the Effective Time, are subject to a "substantial risk of
forfeiture" within the meaning of Section 83 of the Code.

        "Hydrocarbon Stockholder Approval" shall have the meaning set forth in
Section 7.1.

        "Hydrocarbon Stock Options" means all employee and director stock
options to purchase shares of Hydrocarbon Common Stock pursuant to awards
granted under any of the Hydrocarbon Stock Option Plans.

4

--------------------------------------------------------------------------------

        "Hydrocarbon Stock Option Plans" shall mean the Hydrocarbon 2006 Stock
Incentive Plan, the Hydrocarbon 1996 Stock Incentive Plan, the Hydrocarbon 1996
Non-Employee Director Stock Option Plan and any other plan pursuant to which any
Hydrocarbon Stock Option is granted.

        "Hydrocarbon Termination Fee" shall mean an amount equal to $15 million
in cash; provided, however, if Hydrocarbon terminates in accordance with
Section 8.1(d)(i) and enters into a definitive agreement with respect to a
Superior Proposal prior to the No Solicitation Start Date or a definitive
agreement with an Excluded Party, then "Hydrocarbon Termination Fee" shall mean
an amount equal to $7.5 million in cash.

        "Hydrocarbon's Disclosure Schedule" shall mean the Disclosure Schedule
delivered by Hydrocarbon pursuant to Section 5.1.

        "HSR" shall mean the Hart-Scott-Rodino Antitrust Improvements Act of
1976, as amended, and the rules and regulations thereunder.

        "IDRs" shall mean the Incentive Distribution Rights as defined in the
Partnership Agreement.

        "Indemnification Expenses" shall have the meaning set forth in
Section 6.12(a).

        "Indemnified Party" shall have the meaning set forth in Section 6.12(a).

        "Joint Proxy Statement" shall have the meaning set forth in
Section 6.3(a).

        "Lien" shall mean any charge, mortgage, pledge, security interest,
restriction, claim, lien, or encumbrance.

        "LLC Act" shall have the meaning set forth in Section 2.2(b).

        "Mailing Date" shall have the meaning set forth in Section 3.2(a).

        "Material Adverse Effect" shall mean, with respect to either Hydrocarbon
or Energy Partners, any effect that (i) is or could reasonably be expected to be
material and adverse to the financial position, results of operations, business
or assets of Hydrocarbon and its Subsidiaries taken as a whole, or Energy
Partners and its Subsidiaries taken as a whole, respectively, or (ii) materially
impairs or could reasonably be expected to materially impair the ability of
Hydrocarbon or Energy Partners, respectively, to perform its obligations under
this Agreement or otherwise materially threaten or materially impede the
consummation of the Redemption and Merger and the other transactions
contemplated by this Agreement; provided, however, that Material Adverse Effect
shall not be deemed to include the impact of (a) circumstances affecting the
gathering, processing or fractionation of natural gas companies generally,
(b) the natural gas pipeline, treating and processing industry generally
(including the price of natural gas and the cost associated with the drilling
and/or production of natural gas), (c) any general market, economic, financial
or political conditions, or outbreak or hostilities or war, in the United States
or (d) the effects of the Redemption and Merger and compliance by either party
with the provisions of this Agreement on the financial position, results of
operations, business or assets of such party and its Subsidiaries, or the other
party and its Subsidiaries, as the case may be, so long as, in the case of
clauses (a), (b) or (c), the impact on Hydrocarbon or Energy Partners is not
disproportionately adverse as compared to others in the industry.

        "Meeting" shall have the meaning set forth in Section 6.2.

        "Merger" shall have the meaning set forth in the recitals to this
Agreement.

        "MergerCo" shall have the meaning set forth in the introductory
paragraph in this Agreement.

        "Multiemployer Plans" shall have the meaning set forth in
Section 5.3(l)(iii).

        "No-Solicitation Period Start Date" means 30 days immediately following
the date of this Agreement.

5

--------------------------------------------------------------------------------

        "Non-Electing Shares" shall have the meaning set forth in
Section 3.2(b).

        "Non-Compliance Event" shall have the meaning set forth in
Section 5.3(i)(i).

        "Non-Compliance Notification" shall have the meaning set forth in
Section 5.3(i)(iii).

        "Non-Qualifying Income Cushion" shall have the meaning set forth in
Section 9.1(g).

        "NYSE" shall mean the New York Stock Exchange.

        "Partnership Agreement" shall mean the Second Amended and Restated
Agreement of Limited Partnership of Energy Partners, as in effect immediately
prior to the Effective Time.

        "Pension Plan" shall have the meaning set forth in Section 5.3(l)(iii).

        "Per Share Cash Consideration" shall have the meaning set forth in
Section 3.1(a).

        "Per Share Consideration" shall mean the quotient, rounded to the
nearest ten-thousandth, obtained by dividing the Aggregate Consideration by the
Total Common Stock Amount.

        "Per Share Stated Cash Consideration" shall mean the product, rounded to
the nearest ten-thousandth, of (x) $20 multiplied by (y) a fraction, the
numerator of which is the Deemed Stock Amount and the denominator of which is
the Total Common Stock Amount.

        "Per Share Stated Unit Consideration" shall mean a number (which need
not be a whole number) of Common Units equal to the product, rounded to the
nearest ten-thousandth, of (x) 1.285 multiplied by (y) a fraction, the numerator
of which is the Deemed Stock Amount and the denominator of which is the Total
Common Stock Amount.

        "Per Share Unit Consideration" shall mean a number (which need not be a
whole number) of Common Units equal to the Exchange Ratio.

        "Permitting Violation" shall have the meaning set forth in
Section 5.3(i)(ii).

        "Person" or "person" shall mean any individual, bank, corporation,
partnership, limited liability company, association, joint-stock company,
business trust or unincorporated organization.

        "Plans" shall have the meaning set forth in Section 5.3(l)(iii).

        "Previously Disclosed" by a party shall mean information set forth in
its Disclosure Schedule.

        "Redemption" shall mean redemption of shares of Hydrocarbon Common Stock
pursuant to and in accordance with the Redemption Charter Amendment.

        "Redemption Charter Amendment" shall mean the Certificate of Amendment
to the Certificate of Incorporation of Hydrocarbon in the form attached hereto
as Annex B.

        "Redemption/Exchange Agent" shall mean Wells Fargo, N.A. or such other
entity as may be selected by Energy Partners subject to the reasonable approval
of Hydrocarbon.

        "Redemption/Merger Consideration" shall have the meaning set forth in
Section 3.1(b).

        "Redemption Shares" shall mean all Stated Consideration Cash Shares and
all Cash Election Shares unless (1) the aggregate cash amount that would be paid
upon the redemption of the Cash Election Shares is greater than the Total
Remaining Cash Amount, in which case only the Stated Consideration Cash Shares
and those Cash Election Shares that are not Unit Designated Shares shall
constitute Redemption Shares, or (2) the aggregate cash amount that would be
paid upon the redemption of the Cash Election Shares is less than the Total
Remaining Cash Amount, in which case all Stated Consideration Cash Shares, Cash
Election Shares and Cash Designated Shares shall constitute Redemption Shares.
Redemption Shares shall not include Treasury Shares, shares held by

6

--------------------------------------------------------------------------------

Energy Partners or its Subsidiaries and, to the fullest extent permitted by law,
shares of Dissenting Holders and Hydrocarbon Restricted Stock.

        "Registration Statement" shall have the meaning set forth in
Section 6.3(a).

        "Regulatory Authorities" shall have the meaning set forth in
Section 5.3(h)(ii).

        "Representatives" shall mean with respect to a Person, its directors,
officers, employees, agents and representatives, including any investment
banker, financial advisor, attorney, accountant or other advisor, agent or
representative; provided, however, that John Fox shall not be considered a
Representative for purposes of this Agreement.

        "Restructuring Transactions" shall mean the following, collectively, as
provided for in the Exchange Agreement: the exchange by Hydrocarbon of its
4,938,992 Common Units for Class A Units and the exchange by the General Partner
of its 2% economic interest in Energy Partners and the IDRs for Class A Units.

        "Rights" shall mean, with respect to any person, securities or
obligations convertible into or exchangeable for, or giving any person any right
to subscribe for or acquire, or any options, calls or commitments relating to,
equity securities of such person.

        "Rule 145 Affiliate" shall have the meaning set forth in Section 6.7(a).

        "SEC" shall mean the Securities and Exchange Commission.

        "SEC Documents" shall have the meaning set forth in Section 5.3(g).

        "Securities Act" shall mean the Securities Act of 1933, as amended, and
the rules and regulations thereunder.

        "Significant Subsidiaries" shall have the meaning ascribed to such term
in Section 1-01(w) of Regulation S-X under the Securities Act.

        "Stated Consideration" shall mean an amount equal to the Per Share
Stated Cash Consideration plus the Per Share Stated Unit Consideration.

        "Stated Consideration Cash Shares" shall have the meaning set forth in
Section 3.2(b).

        "Stated Consideration Shares" shall have the meaning set forth in
Section 3.2(b).

        "Stated Consideration Unit Shares" shall have the meaning set forth in
Section 3.2(b).

        "Subordinated Units" shall mean the subordinated units representing
limited partner interests of Energy Partners having the rights and obligations
specified with respect to Subordinated Units in the Partnership Agreement.

        "Subsidiary" shall have the meaning ascribed to such term in Rule 1-02
of Regulation S-X under the Securities Act, except, in the case of Hydrocarbon,
Energy Partners and its Subsidiaries shall not be deemed to be Subsidiaries of
Hydrocarbon.

        "Superior Proposal" means any Acquisition Proposal (except that
references to 20% within the definition of "Acquisition Proposal" shall be
replaced by "50%") made by a third party on terms that the Hydrocarbon Board
(acting through the Deal Committee) determines, in its good faith judgment,
after consulting with its or the Deal Committee's, as applicable, financial
advisors and outside legal counsel, and taking into account all financial,
legal, regulatory and other aspects of the Acquisition Proposal (i) to be more
favorable to Hydrocarbon's stockholders, including the Unaffiliated
Stockholders, from a financial point of view than the Redemption and Merger,
taken together, and (ii) that is reasonably capable of being consummated.

        "Surviving Entity" shall have the meaning set forth in Section 2.2(a).

7

--------------------------------------------------------------------------------

        "Takeover Law" means any "fair price," "moratorium," "control share
acquisition," "business combination" or any other anti-takeover statute or
similar statute enacted under state or federal law.

        "Taxes" shall mean all taxes, charges, fees, levies or other
assessments, including, without limitation, all net income, gross income, gross
receipts, sales, use, ad valorem, goods and services, capital, transfer,
franchise, profits, license, withholding, payroll, employment, employer health,
excise, estimated, severance, stamp, occupation, property or other taxes, custom
duties, fees, assessments or charges of any kind whatsoever, together with any
interest and any penalties, additions to tax or additional amounts imposed by
any taxing authority.

        "Tax Returns" shall have the meaning set forth in Section 5.3(o).

        "Termination Date" shall have the meaning set forth in
Section 8.1(b)(i).

        "Total Cash Amount" shall mean the product obtained by multiplying
(x) $20.00 by (y) the Deemed Stock Amount.

        "Total Common Stock Amount" shall mean the total number of shares of
Hydrocarbon Common Stock, less the number of shares of Hydrocarbon Restricted
Stock, outstanding immediately prior to the Redemption, which shall take place
immediately prior to the Effective Time.

        "Total Remaining Cash Amount" shall mean the amount of cash equal to the
(x) Total Cash Amount minus (y) the Total Stated Consideration Cash Amount.

        "Total Stated Consideration Cash Amount" shall mean the product obtained
by multiplying (x) the Per Share Cash Consideration by (y) the total number of
Stated Consideration Cash Shares.

        "Total Stock Amount" shall mean the product obtained by multiplying
(x) 1.285 by (y) the Deemed Stock Amount.

        "Total Stock Consideration" shall mean the product obtained by
multiplying (x) the Total Stock Amount by (y) the Final Energy Partners Unit
Price.

        "Treasury Shares" shall mean shares of Hydrocarbon Common Stock owned by
Hydrocarbon or any of its Subsidiaries at the Effective Time.

        "Unaffiliated Stockholders" means the holders of Hydrocarbon Common
Stock, other than John M. Fox and MWHC Holdings Inc., their respective
affiliates, and the respective officers and directors of Hydrocarbon and the
General Partner.

        "Unit Designated Shares" shall have the meaning set forth in
Section 3.2(e)(i)(B).

        "Unit Election Shares" shall have the meaning set forth in
Section 3.2(b).

        "Unit Issuance" shall mean (i) the issuance of Common Units in the
Merger pursuant to this Agreement and (ii) the issuance of Class A Units to
Hydrocarbon and the General Partner in the Restructuring Transactions.

        "Unit Majority" shall mean the Unit Majority as defined in the
Partnership Agreement.

        "Valuation Period" shall mean the ten consecutive trading days during
which the Common Units are traded on the NYSE, ending on the third calendar day
immediately prior to the Effective Time, or if such calendar day is not a
trading day, then ending on the trading day immediately preceding such calendar
day.

8

--------------------------------------------------------------------------------

ARTICLE II

THE REDEMPTION AND MERGER; EFFECTS OF THE MERGER

        Section 2.1    The Redemption.    

        (a)    Amendment to Hydrocarbon Charter.    The Hydrocarbon Board, in
connection with the execution of this Agreement, has adopted the Redemption
Charter Amendment.

        (b)    The Redemption.    Upon the effectiveness of the Redemption
Charter Amendment and immediately prior to the Effective Time of the Merger, as
provided in the Redemption Charter Amendment, each Redemption Share shall be
redeemed at a redemption price equal to the Per Share Cash Consideration. Such
Per Share Cash Consideration shall be paid in accordance with the procedures for
payment thereof to holders of Certificates as set forth in Section 3.5.

        Section 2.2    The Merger.    

        (a)    The Surviving Entity.    Subject to the terms and conditions of
this Agreement, at the Effective Time, which shall be immediately following the
Redemption, MergerCo shall merge with and into Hydrocarbon, the separate
existence of MergerCo shall cease and Hydrocarbon shall survive and continue to
exist as a Delaware entity (Hydrocarbon, as the surviving corporation in the
Merger, sometimes being referred to herein as the "Surviving Entity"), such that
following the Merger, Hydrocarbon will be a direct, wholly owned subsidiary of
Energy Partners.

        (b)    Effectiveness and Effects of the Merger.    Subject to the
satisfaction or waiver of the conditions set forth in Article VII in accordance
with this Agreement, the Merger shall become effective upon the later to occur
of the filing in the office of the Secretary of State of the State of Delaware
of a properly executed certificate of merger (the "Certificate of Merger") or
such later date and time as may be set forth in the Certificate of Merger (the
"Effective Time"), in accordance with the DGCL and the Delaware Limited
Liability Company Act (the "LLC Act"). The Merger shall have the effects
prescribed in the DGCL and the LLC Act.

        (c)    Certificate of Incorporation and Bylaws.    At the Effective
Time, the Hydrocarbon Charter shall be amended in its entirety to read as set
forth in Annex C, and as so amended shall be the certificate of incorporation of
the Surviving Entity, until duly amended in accordance with the terms thereof
and applicable law. At the Effective Time, the Hydrocarbon Bylaws shall be
amended in its entirety to read as set forth in Annex D, and as so amended shall
be the bylaws of the Surviving Entity until duly amended in accordance with the
terms of the certificate of incorporation of the Surviving Entity, such bylaws
and applicable law.

        (d)    Directors of the Surviving Entity.    Frank M. Semple, Nancy K.
Buese and Andrew L. Schroeder shall be the directors of the Surviving Entity as
of the Effective Time, until their respective successors are duly elected or
appointed and qualified or their earlier death, resignation or removal in
accordance with the certificate of incorporation and bylaws of the Surviving
Entity.

        (e)    Officers of the Surviving Entity.    The officers of Hydrocarbon
immediately prior to the Effective Time shall be the officers of the Surviving
Entity as of the Effective Time, until their respective successors are duly
elected or appointed and qualified or their earlier death, resignation or
removal in accordance with the certificate of incorporation and bylaws of the
Surviving Entity.

        Section 2.3    Closing.    Subject to the satisfaction or waiver of the
conditions as set forth in Article VII in accordance with this Agreement, the
filing of the Redemption Charter Amendment, followed by the filing of the
Certificate of Merger (as defined herein) with the Delaware Secretary of State,
and the closing of the Redemption, the Restructuring Transactions, the Merger
and the other transactions contemplated hereby (the "Closing") shall occur on
(a) the third business day after the day on which the last of the conditions set
forth in Article VII shall have been satisfied or waived in

9

--------------------------------------------------------------------------------

accordance with the terms of this Agreement or (b) such other date to which the
parties may agree in writing. The date on which the Closing occurs is referred
to as the "Closing Date." The Closing of the transactions contemplated by this
Agreement shall take place at the offices of Hogan & Hartson L.L.P., One Tabor
Center, Suite 1500, 1200 Seventeenth Street, Denver, Colorado 80202, at
10:00 a.m. local time on the Closing Date.

ARTICLE III

REDEMPTION AND MERGER CONSIDERATION; EXCHANGE PROCEDURES

        Section 3.1    Redemption and Merger Consideration.    Subject to the
provisions of this Agreement:

        (a)   By virtue of the Redemption, each Redemption Share shall be
redeemed upon the effectiveness of the Charter Amendment immediately prior to
the Effective Time for cash in an amount having a value equal to the Per Share
Consideration in the Redemption (the "Per Share Cash Consideration").

        (b)   By virtue of the Merger, at the Effective Time each share of
Hydrocarbon Common Stock issued and outstanding immediately prior to the
Effective Time that has not been redeemed pursuant to the Redemption (other than
Treasury Shares, shares held by Energy Partners or its Subsidiaries and, to the
fullest extent permitted by law, shares of Dissenting Holders and Hydrocarbon
Restricted Stock) shall be converted into the Per Share Unit Consideration. The
Per Share Unit Consideration, together with the Per Share Cash Consideration,
shall be referred to herein as the "Redemption/Merger Consideration."

        (c)   By virtue of the Redemption, the Total Cash Amount deposited by
Hydrocarbon with the Redemption/Exchange Agent will be used to redeem shares of
Hydrocarbon Common Stock and such shares of Hydrocarbon Common Stock shall be
treated as redeemed and canceled immediately prior to the Merger.

        (d)   By virtue of the Merger, all of the limited liability company
interests in MergerCo outstanding immediately prior to the Effective Time shall
be converted into and become 1,000 fully paid and nonassessable shares of common
stock of the Surviving Corporation.

        (e)   By virtue of the Merger, each Treasury Share and each share of
Hydrocarbon Common Stock owned by Energy Partners or its Subsidiaries shall
cease to be outstanding and shall be canceled without payment of any
consideration therefor, and no partnership interest of Energy Partners or other
consideration shall be delivered in exchange therefor.

        (f)    All shares of Hydrocarbon Common Stock, when redeemed in the
Redemption or converted in the Merger, shall cease to be outstanding and shall
automatically be canceled and cease to exist. Each holder of a certificate (a
"Certificate") previously representing any such shares shall cease to have any
rights with respect thereto, except the right to receive (i) the
Redemption/Merger Consideration, (ii) any distributions in accordance with
Section 3.5(c) and (iii) any cash to be paid in lieu of any fractional Common
Unit in accordance with Section 3.5(e), in each case to be issued or paid in
consideration therefor upon the surrender of such Certificates in accordance
with Section 3.5.

        Section 3.2    Election Procedures.    

        (a)   An election form and other appropriate and customary transmittal
materials (which shall specify that delivery shall be effected, and risk of loss
and title to the Certificates theretofore representing shares of Hydrocarbon
Common Stock shall pass, only upon proper delivery of such Certificates to the
Redemption/Exchange Agent) in such form as Energy Partners and Hydrocarbon shall
mutually agree (the "Election Form") and pursuant to which each holder of record
of shares of Hydrocarbon Common Stock as of the close of business on the
Election Deadline may make an election pursuant to this Section 3.2, shall be
mailed at the same time as the Joint Proxy Statement or

10

--------------------------------------------------------------------------------

at such other time as Hydrocarbon and Energy Partners may agree (the date on
which such mailing is commenced or such other agreed date, the "Mailing Date")
to each holder of record of Hydrocarbon Common Stock as of the close of business
on the record date for notice of the Hydrocarbon Meeting (the "Election Form
Record Date").

        (b)   Each Election Form shall permit the holder (or the beneficial
owner through appropriate and customary documentation and instructions), other
than any holder of Appraisal Shares, to specify (i) the number of such holder's
shares of Hydrocarbon Common Stock with respect to which such holder elects to
have redeemed for the Per Share Cash Consideration in the Redemption ("Cash
Election Shares"), (ii) the number of such holder's shares of Hydrocarbon Common
Stock with respect to which such holder elects to have exchanged for the Per
Share Unit Consideration in the Merger ("Unit Election Shares"), (iii) the
number of such holder's shares of Hydrocarbon Common Stock with respect to which
such holder elects to receive the Stated Consideration (the "Stated
Consideration Shares"), a portion of which shares shall be Stated Consideration
Cash Shares to be redeemed for the Per Share Cash Consideration in the
Redemption, and a portion of which shares shall be Stated Consideration Unit
Shares to be exchanged for the Per Share Unit Consideration in the Merger, both
as provided for herein, and (iv) the number of such holder's shares of
Hydrocarbon Common Stock with respect to which such holder makes no election
("Non-Electing Shares"). For each holder electing to receive the Stated
Consideration, (x) that number of such holder's Stated Consideration Shares
equal to the quotient obtained by dividing (1) the product of the Per Share
Stated Cash Consideration multiplied by the number of such holder's Stated
Consideration Shares by (2) the Per Share Cash Consideration, rounded to the
nearest whole share, shall be deemed "Stated Consideration Cash Shares"
hereunder and (y) that number of such holder's Stated Consideration Shares equal
to (1) the number of such holder's Stated Consideration Shares minus (2) the
number of such holder's Stated Consideration Cash Shares shall be deemed "Stated
Consideration Unit Shares" hereunder. Any Hydrocarbon Common Stock with respect
to which the Redemption/Exchange Agent has not received an effective, properly
completed Election Form on or before 5:00 p.m., New York City time, on the 33rd
day following the Mailing Date (or such other time and date as Hydrocarbon and
Energy Partners shall agree) (the "Election Deadline") (other than any shares of
Hydrocarbon Common Stock that constitute Appraisal Shares as of such time) shall
also be deemed to be Non-Electing Shares. In addition, any shares of Hydrocarbon
Common Stock treated as outstanding upon the exercise of Hydrocarbon Stock
Options pursuant to Section 3.7(a) shall be deemed to be Non-Electing Shares.

        (c)   Hydrocarbon and Energy Partners shall mail one or more Election
Forms as may reasonably be requested from time to time by all Persons who become
holders (or beneficial owners) of Hydrocarbon Common Stock between the Election
Form Record Date and the close of business on the Business Day prior to the
Election Deadline. Hydrocarbon shall provide to the Redemption/Exchange Agent
all information reasonably necessary for it to perform as specified herein.

        (d)   Any such election shall have been properly made only if the
Redemption/Exchange Agent shall have actually received a properly completed
Election Form by the Election Deadline. An Election Form shall be deemed
properly completed only if accompanied by (i) one or more Certificates (or
customary affidavits and indemnification regarding the loss or destruction of
such Certificates or the guaranteed delivery of such Certificates) representing
all certificated shares of Hydrocarbon Common Stock covered by such Election
Form or (ii) in the case of shares in book-entry form, any additional documents
specified by the procedures set forth in the Election Form, together with duly
executed transmittal materials included in the Election Form. Any Election Form
may be revoked or changed by the Person submitting such Election Form prior to
the Election Deadline. In the event an Election Form is revoked prior to the
Election Deadline, the shares of Hydrocarbon Common Stock represented by such
Election Form shall become Non-Electing Shares and Energy Partners shall cause
the Certificates, if any, representing Hydrocarbon Common Stock to be promptly
returned without charge to the Person submitting the Election Form upon written
request to that effect from the holder who

11

--------------------------------------------------------------------------------

submitted the Election Form, except to the extent (if any) a subsequent election
is properly made with respect to any or all of the applicable shares of
Hydrocarbon Common Stock. Subject to the terms of this Agreement and of the
Election Form, the Redemption/Exchange Agent shall have reasonable discretion to
determine whether any election, revocation or change has been properly or timely
made and to disregard immaterial defects in the Election Forms, and any good
faith decisions of the Redemption/Exchange Agent regarding such matters shall be
binding and conclusive. None of Energy Partners, MergerCo or the
Redemption/Exchange Agent shall be under any obligation to notify any Person of
any defect in an Election Form.

        (e)   Within ten Business Days after the Election Deadline, unless the
Effective Time has not yet occurred, in which case as soon after the Effective
Time as practicable (and in no event more than ten Business Days after the
Effective Time), Hydrocarbon and Energy Partners shall cause the
Redemption/Exchange Agent to effect the allocation among the holders of shares
of Hydrocarbon Common Stock of rights to receive cash in the Redemption or
Common Units in the Merger in accordance with the Election Forms (subject to
compliance with the provisions of this Agreement) as follows:

        (i)    Cash Election Shares More Than Total Remaining Cash Amount.    If
the aggregate cash amount that would be paid upon the redemption of the Cash
Election Shares in the Redemption is greater than the Total Remaining Cash
Amount, then:

(A)all Unit Election Shares, Stated Consideration Unit Shares and Non-Electing
Shares shall be exchanged for the Per Share Unit Consideration in the Merger,

(B)the Redemption/Exchange Agent shall then select from among the Cash Election
Shares, by a pro rata selection process based on the number of shares held by a
stockholder, a sufficient number of shares ("Unit Designated Shares") such that
the aggregate cash amount that will be paid in the Redemption equals as closely
as practicable the Total Cash Amount (such calculation to take into
consideration the number of Stated Consideration Cash Shares and the Total
Stated Cash Consideration Amount), and all Unit Designated Shares shall be
exchanged for the Per Share Unit Consideration in the Merger, and

(C)all Stated Consideration Cash Shares and those Cash Election Shares that are
not Unit Designated Shares shall be redeemed at a redemption price per share
equal to the Per Share Cash Consideration in the Redemption.

        (ii)    Cash Election Shares Less Than Total Remaining Cash
Amount.    If the aggregate cash amount that would be paid upon the redemption
of the Cash Election Shares in the Redemption is less than the Total Remaining
Cash Amount, then:

(A)all Cash Election Shares and Stated Consideration Cash Shares shall be
redeemed at a redemption price per share equal to the Per Share Cash
Consideration in the Redemption,

(B)the Redemption/Exchange Agent shall then select first from among the
Non-Electing Shares and then (if necessary) from among the Unit Election Shares,
by a pro rata selection process based on the number of shares held by a
stockholder, a sufficient number of shares ("Cash Designated Shares") such that
the aggregate cash amount that will be paid in the Redemption equals as closely
as practicable the Total Cash Amount (such calculation to take into
consideration the number of Stated Consideration Cash Shares and the Total
Stated Cash Consideration Amount), and all Cash Designated Shares shall be
redeemed at a redemption price per share equal to the Per Share Cash
Consideration in the Redemption, and

12

--------------------------------------------------------------------------------

(C)all Stated Consideration Unit Shares and those Unit Election Shares and the
Non-Electing Shares that are not Cash Designated Shares shall be exchanged for
the Per Share Unit Consideration in the Merger.

        (iii)    Cash Election Shares Equal to Total Remaining Cash
Amount.    If the aggregate cash amount that would be paid upon the redemption
of the Cash Election Shares in the Redemption is equal to the Total Remaining
Cash Amount, then subparagraphs (i) and (ii) above shall not apply and all Cash
Election Shares and Stated Consideration Cash Shares shall be redeemed at a
redemption price per share equal to the Per Share Cash Consideration in the
Redemption and all Unit Election Shares, Stated Consideration Unit Shares and
Non-Electing Shares shall be exchanged for the Per Share Unit Consideration in
the Merger.

        Notwithstanding anything in this Agreement to the contrary, to the
fullest extent permitted by law, for purposes of determining the allocations set
forth in this Section 3.2, Energy Partners shall have the right to require, but
not the obligation to require, that any shares of Hydrocarbon Common Stock that
constitute Appraisal Shares as of the Election Deadline be treated as Cash
Election Shares but not be subject to the pro rata selection process
contemplated by this Section 3.2, and, if Energy Partners so requires, then, to
the fullest extent permitted by law, any Appraisal Shares that receive the
Redemption/Merger Consideration provided under this Article III shall be treated
as Cash Election Shares but not be subject to the pro rata selection process
contemplated by this Section 3.2.

        (f)    The pro rata selection process to be used by the
Redemption/Exchange Agent shall consist of such equitable pro ration processes
as shall be mutually determined by Energy Partners and Hydrocarbon.

        Section 3.3    Appraisal Rights.    Notwithstanding anything in this
Agreement to the contrary, shares of Hydrocarbon Common Stock issued and
outstanding immediately prior to the filing of the Redemption Charter Amendment
or the Effective Time that are held by any record holder who is entitled to
demand and properly demands appraisal of such shares pursuant to, and who
complies in all respects with, the provisions of Section 262 of the DGCL (the
"Appraisal Shares") shall not be converted into the right to receive the
Redemption/Merger Consideration, but instead shall become the right to payment
of the fair value of such shares in accordance with the provisions of
Section 262 of the DGCL and the Redemption Charter Amendment and at the filing
of the Redemption Charter Amendment or the Effective Time, all Appraisal Shares
shall no longer be outstanding and shall automatically be canceled and cease to
exist. Notwithstanding the foregoing, if any such holder shall fail to perfect
or otherwise shall waive, withdraw or lose the right to appraisal under
Section 262 of the DGCL or a court of competent jurisdiction shall determine
that such holder is not entitled to the relief provided by Section 262 of the
DGCL, then the right of such holder to be paid the fair value of such holder's
Appraisal Shares under Section 262 of the DGCL and the Redemption Charter
Amendment shall be forfeited and cease and if such forfeiture shall occur
following the Election Deadline, each of such holder's Appraisal Shares, to the
extent permitted by law, shall be treated as Non-Electing Shares or pursuant to
Section 3.2(e) as Cash Election Shares. Hydrocarbon shall deliver prompt notice
to Energy Partners of any demands for appraisal of any shares of Hydrocarbon
Common Stock and provide Energy Partners with the opportunity to participate in
all negotiations and proceedings with respect to demands for appraisal. Prior to
the Effective Time, Hydrocarbon shall not, without the prior written consent of
Energy Partners, make any payment with respect to, or settle or offer to settle,
any such demands, or agree to do any of the foregoing.

        Section 3.4    Rights As Stockholders; Stock Transfers.    After the
Redemption or the Effective Time, as the case may be, holders of Hydrocarbon
Common Stock shall cease to be, and shall have no rights, as stockholders of
Hydrocarbon, other than to receive (a) any dividend or other distribution with
respect to such Hydrocarbon Common Stock with a record date occurring prior to
the Effective Time that may have been declared or made by Hydrocarbon on such
shares of Hydrocarbon Common Stock

13

--------------------------------------------------------------------------------

in accordance with the terms of this Agreement or prior to the date hereof and
which remain unpaid at the Effective Time and (b) the consideration provided
under this Article III. After the Effective Time, there shall be no transfers on
the stock transfer books of the shares of Hydrocarbon Common Stock.

        Section 3.5    Exchange of Certificates.    

        (a)    Redemption/Exchange Agent.    Hydrocarbon shall irrevocably
deposit with the Redemption/Exchange Agent an amount in cash that shall be
sufficient to effect the Redemption, and Energy Partners shall deposit or shall
cause to be deposited the Common Units for the Merger with the
Redemption/Exchange Agent, in each case for the benefit of the holders of shares
of Hydrocarbon Common Stock and both of which together shall be used to make all
deliveries of cash and the Common Units as required by and pursuant to this
Article III. Energy Partners agrees to make available to the Redemption/Exchange
Agent, from time to time as needed, cash sufficient to pay any distributions
pursuant to Section 3.5(c) and to make payments in lieu of any fractional Common
Units pursuant to Section 3.5(e). Any cash and Common Units deposited with the
Redemption/Exchange Agent (including as payment for any fractional Common Units
in accordance with Section 3.5(e) and any distributions in accordance with
Section 3.5(c)) shall hereinafter be referred to as the "Exchange Fund." The
Redemption/Exchange Agent shall, pursuant to irrevocable instructions, deliver
the Redemption/Merger Consideration contemplated to be paid for shares of
Hydrocarbon Common Stock pursuant to this Agreement, both through the Redemption
and through the Merger, out of the Exchange Fund. Except as contemplated by
Sections 3.5(c) and 3.5(e) hereof, the Exchange Fund shall not be used for any
other purpose.

        (b)    Exchange Procedures.    Promptly after the Effective Time, Energy
Partners shall instruct the Redemption/Exchange Agent to mail to each record
holder of Certificates (other than such holders who have properly completed an
Election form and elected the shares with respect to such Certificates as Cash
Election Shares, Unit Election Shares, Stated Consideration Shares or
Non-Electing Shares in accordance with Section 3.2 and other than Appraisal
Shares), (i) a letter of transmittal (which shall specify that delivery shall be
effected, and risk of loss and title to the Certificates shall pass, only upon
proper delivery of the Certificates to the Redemption/Exchange Agent, and shall
be in customary form and agreed to by Energy Partners and Hydrocarbon prior to
the Effective Time) and (ii) instructions for use in effecting the surrender of
the Certificates in exchange for the Redemption/Merger Consideration payable in
respect of the shares of Hydrocarbon Common Stock represented by such
Certificates. Promptly after the Effective Time, upon surrender of Certificates
for cancellation to the Redemption/Exchange Agent together with such letters of
transmittal, properly completed and duly executed, and such other documents as
may be required pursuant to such instructions, the holders of such Certificates
and the holders of Certificates who previously surrendered Certificates to the
Redemption/Exchange Agent with properly completed and duly executed Election
Forms shall be entitled to receive in exchange therefor (A) Common Units
representing, in the aggregate, the whole number of Common Units that such
holder has the right to receive pursuant to this Article III (after taking into
account all shares of Hydrocarbon Common Stock then held by such holder) and
(B) a check in the amount equal to the aggregate amount of cash that such holder
has the right to receive pursuant to this Article III, including cash payable in
lieu of any fractional Common Units pursuant to Section 3.5(e) and distributions
pursuant to Section 3.5(c). No interest shall be paid or accrued on any
Redemption/Merger Consideration, cash in lieu of fractional shares or on any
unpaid dividends and distributions payable to holders of Certificates. In the
event of a transfer of ownership of shares of Hydrocarbon Common Stock which is
not registered in the transfer records of Hydrocarbon, the Redemption/Merger
Consideration payable in respect of such shares of Hydrocarbon Common Stock may
be paid to a transferee if the Certificate representing such shares of
Hydrocarbon Common Stock is presented to the Redemption/Exchange Agent,
accompanied by all documents required to evidence and effect such transfer and
the Person requesting such exchange shall pay to the Redemption/Exchange Agent
in advance any transfer or other Taxes required by reason of the delivery of the

14

--------------------------------------------------------------------------------

Redemption/Merger Consideration in any name other than that of the registered
holder of the Certificate surrendered, or shall establish to the satisfaction of
the Redemption/Exchange Agent that such Taxes have been paid or are not payable.
Until surrendered as contemplated by this Section 3.5, each Certificate other
than Certificates representing Appraisal Shares shall be deemed at any time
after the Effective Time to represent only the right to receive upon such
surrender the Redemption/Merger Consideration payable in respect of the shares
of Hydrocarbon Common Stock represented by such Certificate and any
distributions to which such holder is entitled pursuant to Section 3.4.

        (c)    Distributions with Respect to Unexchanged Common Units.    No
distributions declared or made with respect to Common Units with a record date
after the Effective Time shall be paid to the holder of any unsurrendered
Certificate representing Hydrocarbon Common Stock with respect to the Common
Units that such holder would be entitled to receive upon surrender of such
Certificate and no cash payment in lieu of fractional Common Units shall be paid
to any such holder until such holder shall surrender such Certificate in
accordance with this Section 3.5. Subject to applicable law, following surrender
of any such Certificate, there shall be paid to such holder of the Common Units
issuable in exchange therefor, without interest, (i) promptly after the time of
such surrender, the amount of any cash due pursuant to Section 3.2 and cash
payable in lieu of fractional Common Units to which such holder is entitled
pursuant to Section 3.5(e) and the amount of distributions with a record date
after the Effective Time theretofore paid with respect to the Common Units and
payable with respect to such Common Units, and (ii) at the appropriate payment
date, the amount of distributions with a record date after the Effective Time
but prior to such surrender and a payment date subsequent to such surrender
payable with respect to such Common Units.

        (d)    No Further Rights in Hydrocarbon Common Stock.    The
Redemption/Merger Consideration delivered or issued, as the case may be, in
accordance with the terms hereof (including any cash paid pursuant to
Section 3.4, Section 3.5(c) or Section 3.5(e)) shall be deemed to have been
issued in full satisfaction of all rights pertaining to such share of
Hydrocarbon Common Stock.

        (e)    Fractional Common Units.    No certificates or scrip of the
Common Units representing fractional Common Units or book entry credit of the
same shall be issued upon the surrender for exchange of Certificates in the
Merger, and such fractional interests will not entitle the owner thereof to vote
or to have any rights as a holder of any Common Units. Notwithstanding any other
provision of this Agreement, each holder of shares of Hydrocarbon Common Stock
exchanged in the Merger who would otherwise have been entitled to receive a
fraction of a Common Unit (after taking into account all Certificates delivered
by such holder) shall receive, in lieu thereof, cash (without interest rounded
up to the nearest whole cent) in an amount equal to the product of (i) the
closing sale price of the Common Units on the NYSE as reported by The Wall
Street Journal on the trading day immediately preceding the date on which the
Effective Time shall occur and (ii) the fraction of a Common Unit that such
holder would otherwise be entitled to receive pursuant to this Article III. As
promptly as practicable after the determination of the amount of cash, if any,
to be paid to holders of fractional interests, the Redemption/Exchange Agent
shall so notify Energy Partners, and it shall, or shall cause the Surviving
Entity to, deposit such amount with the Redemption/Exchange Agent and shall
cause the Redemption/Exchange Agent to forward payments to such holders of
fractional interests subject to and in accordance with the terms hereof.

        (f)    Termination of Exchange Fund with Respect to Merger.    Any
portion of the Exchange Fund constituting Common Units that remains
undistributed to the holders of Hydrocarbon Common Stock in the Merger after
180 days following the Effective Time shall be delivered to Energy Partners upon
demand and, from and after such delivery, any former holders of Hydrocarbon
Common Stock (other than Appraisal Shares) who have not theretofore complied
with this Article III shall thereafter look only to Energy Partners for the
Redemption/Merger Consideration payable in the Merger in respect of such shares
of Hydrocarbon Common Stock, any cash in lieu of fractional Common Units to
which they are entitled pursuant to Section 3.5(e) and any distributions with
respect to the Common Units to

15

--------------------------------------------------------------------------------

which they are entitled pursuant to Section 3.5(c), in each case, without any
interest thereon. Any amounts remaining unclaimed by holders of shares of
Hydrocarbon Common Stock immediately prior to such time as such amounts would
otherwise escheat to or become the property of any governmental entity shall, to
the extent permitted by applicable law, become the property of Energy Partners
or Hydrocarbon, as the case may be, free and clear of any Liens, claims or
interest of any Person previously entitled thereto.

        (g)    No Liability.    Neither Energy Partners, Hydrocarbon, nor the
Surviving Entity shall be liable to any holder of shares of Hydrocarbon Common
Stock for any Common Units (or distributions with respect thereto) or cash from
the Exchange Fund delivered to a public official pursuant to any abandoned
property, escheat or similar law.

        (h)    Lost Certificates.    If any Certificate shall have been lost,
stolen or destroyed, upon the making of an affidavit of that fact by the Person
claiming such Certificate to be lost, stolen or destroyed and, if required by
Hydrocarbon or Energy Partners, the posting by such Person of a bond, in such
reasonable amount as Hydrocarbon or Energy Partners may direct, as indemnity
against any claim that may be made against it with respect to such Certificate,
the Redemption/Exchange Agent shall pay in exchange for such lost, stolen or
destroyed Certificate the Redemption/Merger Consideration payable in respect of
the shares of Hydrocarbon Common Stock represented by such Certificate and any
distributions to which the holders thereof are entitled pursuant to Section 3.4.

        (i)    Withholding.    Each of Hydrocarbon, Energy Partners, the
Surviving Entity and the Redemption/Exchange Agent shall be entitled to deduct
and withhold from the consideration otherwise payable pursuant to this Agreement
to any holder of Hydrocarbon Common Stock such amounts as Hydrocarbon, Energy
Partners, the Surviving Entity or the Redemption/Exchange Agent is required to
deduct and withhold under the Code or any provision of state, local, or foreign
Tax law, with respect to the making of such payment. To the extent that amounts
are so withheld, such withheld amounts shall be treated for all purposes of this
Agreement as having been paid to the holder of Hydrocarbon Common Stock in
respect of whom such deduction and withholding was made by Hydrocarbon, Energy
Partners, the Surviving Entity or the Redemption/Exchange Agent, as the case may
be.

        (j)    Book Entry of Common Units.    All Common Units to be issued in
the Merger shall be issued in book entry form, without physical certificates.

        Section 3.6    Anti-Dilution Provisions.    In the event of any
subdivisions, reclassifications, recapitalizations, splits, combinations or
dividends in the form of equity interests with respect to the Common Units and
the Hydrocarbon Common Stock (in each case, as permitted pursuant to
Section 4.3), the number of Common Units to be issued in the Merger, the average
closing sales prices of the Common Units determined in accordance with
Section 3.5(e), the Per Share Cash Consideration, the Per Share Unit
Consideration, the Per Share Stated Cash Consideration and the Per Share Stated
Unit Consideration will be correspondingly adjusted.

        Section 3.7    Options and Restricted Shares.    

        (a)   Immediately prior to the Redemption, Hydrocarbon shall cause all
outstanding Hydrocarbon Stock Options heretofore granted, regardless of whether
or not vested or exercisable at the Effective Time, to be deemed exercised and
each holder of an outstanding Hydrocarbon Stock Option, for purposes of this
Agreement, shall be treated as of the Redemption, which shall occur immediately
prior to the Effective Time, as holding a number of shares of Hydrocarbon Common
Stock equal to (i) the number of shares of Hydrocarbon Common Stock subject to
such Hydrocarbon Stock Option minus (ii) a number of shares of Hydrocarbon
Common Stock that are equal in value, as determined as of the Effective Time, to
(A) (x) the exercise price of such Hydrocarbon Stock Option times (y) the number
of shares of Hydrocarbon Common Stock subject to such Hydrocarbon Stock Option
plus (B) such amounts as are required to be withheld or deducted by Law with
respect to the exercise of such Hydrocarbon Stock Options.

16

--------------------------------------------------------------------------------

        (b)   At the Effective Time, all outstanding shares of Hydrocarbon
Restricted Stock heretofore granted shall cease to represent shares of
Hydrocarbon Restricted Stock and shall be assumed by Energy Partners and
converted into Energy Partners Phantom Units at the Exchange Ratio. Any
fractional Energy Partners Phantom Unit shall be rounded up to the nearest whole
Energy Partners Phantom Unit. Each share of Hydrocarbon Restricted Stock so
assumed and converted shall be subject to, and shall vest upon, the terms and
conditions that are the same as those currently applicable to the shares of
Hydrocarbon Restricted Stock. Promptly after the Effective Time, Energy Partners
will provide each holder of shares of Hydrocarbon Restricted Stock with a notice
describing the assumption and conversion of such shares.

        (c)   With the exception of those Persons who hold shares of Hydrocarbon
Restricted Stock, no Person shall have any right under any plan, program,
agreement or arrangement with respect to Hydrocarbon Common Stock, or for the
issuance or grant of any right of any kind, contingent or accrued, to receive
benefits measured by the value of a number of shares of Hydrocarbon Common Stock
at and after the Effective Time.

ARTICLE IV

ACTIONS PENDING MERGER

        From the date hereof until the Effective Time, except for the
Redemption, the Restructuring Transactions or otherwise as expressly
contemplated by this Agreement, (a) without the prior written consent of the
Conflicts Committee (which consent shall not be unreasonably withheld, delayed
or conditioned), Hydrocarbon will not, and will cause each of its Subsidiaries
not to, and (b) without the prior written consent of the Deal Committee (which
consent shall not be unreasonably withheld, delayed or conditioned), Energy
Partners will not, and will cause each of its Subsidiaries not to:

        Section 4.1    Ordinary Course.    Conduct the business of it and its
Subsidiaries, other than, in the case of Hydrocarbon, Energy Partners and its
Subsidiaries, other than in the ordinary and usual course or, to the extent
consistent therewith, fail to use commercially reasonable best efforts to
preserve intact its business organizations, goodwill and assets and maintain its
rights, franchises and existing relations with customers, suppliers, employees
and business associates, or take any action that would (a) adversely affect the
ability of any party to obtain any approvals required under the HSR for the
transactions contemplated hereby or (b) adversely affect its ability to perform
any of its material obligations under this Agreement.

        Section 4.2    Capital Stock.    In the case of Hydrocarbon and its
Subsidiaries, other than (a) pursuant to stock options Previously Disclosed in
its Disclosure Schedule, or (b) as otherwise set forth on Schedule 4.2 of
Hydrocarbon's Disclosure Schedule, (i) issue, sell or otherwise permit to become
outstanding, or authorize the creation of, any additional shares of capital
stock, any stock appreciation rights or any Rights, (ii) enter into any
agreement with respect to the foregoing or (iii) permit any additional shares of
capital stock to become subject to new grants of employee stock options, stock
appreciation rights or similar stock-based employee rights (other than awards to
newly hired employees consistent with past practice).

        Section 4.3    Dividends, Distributions.    Other than in connection
with the Restructuring Transactions,

        (a)   make, declare or pay any dividend or distribution (except (i) in
the case of Energy Partners, regular quarterly cash distributions of Available
Cash (as defined in the Partnership Agreement) on the Common Units and the
general partner interest of Energy Partners and (ii) in the case of Hydrocarbon,
regular quarterly dividends, in each case in the ordinary course consistent with
past practice but in an amount no greater than the per share dividend for the
second quarter of 2007), on

17

--------------------------------------------------------------------------------

or in respect of, or declare or make any distribution on any shares of its
equity securities other than as Previously Disclosed;

        (b)   split, combine or reclassify any of its capital stock or issue or
authorize or propose the issuance of any other securities in respect of, in lieu
of or in substitution for shares of its capital stock; or

        (c)   repurchase, redeem or otherwise acquire, or permit any of its
Subsidiaries to purchase, redeem or otherwise acquire any shares of its capital
stock, except as required by the terms of its securities outstanding on the date
hereof or as contemplated by any existing Compensation and Benefit Plan.

        Section 4.4    Compensation; Employment Agreements.    In the case of
Hydrocarbon and its Subsidiaries, except as set forth on Schedule 4.4 of
Hydrocarbon's Disclosure Schedule, enter into or amend any written employment,
severance or similar agreements or arrangements with any of its directors,
officers or employees, or grant any salary or wage increase or increase any
employee benefit (including incentive or bonus payments), except for (a) normal
individual increases in compensation to employees (other than officers and
directors) in the ordinary course of business consistent with past practice,
(b) other changes as are provided for herein or as may be required by law or to
satisfy contractual obligations existing as of the date hereof or (c) additional
grants of awards to newly hired employees consistent with past practice.

        Section 4.5    Benefit Plans.    In the case of Hydrocarbon and its
Subsidiaries, except as set forth on Schedule 4.5 of the Hydrocarbon Disclosure
Schedule, enter into or amend (except (i) as may be required by applicable law,
(ii) to satisfy contractual obligations existing as of the date hereof, or
(iii) in the ordinary course of business consistent with past practice which
amendments, either individually or in the aggregate, would not reasonably be
expected to result in a material liability to Hydrocarbon or such Subsidiaries)
any pension, retirement, stock option, stock purchase, savings, profit sharing,
deferred compensation, consulting, bonus, group insurance or other employee
benefit, incentive or welfare contract, plan or arrangement, or any trust
agreement related thereto, in respect of any of its present or former directors,
officers or other employees, including, without limitation, taking any action
that accelerates the vesting or exercise of any benefits payable thereunder.

        Section 4.6    Acquisitions and Dispositions.    In the case of
Hydrocarbon and its Subsidiaries, sell, lease, dispose of or discontinue any
portion of its assets, business or properties, which is material to it and such
Subsidiaries taken as a whole, or acquire, by merger or otherwise, or lease
(other than by way of foreclosures or acquisitions of control in a bona fide
fiduciary capacity or in satisfaction of debts previously contracted in good
faith, in each case in the ordinary and usual course of business consistent with
past practice) any assets or all or any portion of, the business or property of
any other entity which, in either case, is material to it and such Subsidiaries
taken as a whole, or would be likely to have a Material Adverse Effect on the
ability of the parties to consummate the transactions contemplated by this
Agreement or to delay materially the Effective Time. In the case of Energy
Partners, Energy Partners will not, and will cause its Subsidiaries not to,
merge, consolidate or enter into any other business combination transaction with
any Person or make any acquisition or take any other action which would have a
Material Adverse Effect on its ability to consummate the transactions
contemplated by this Agreement.

        Section 4.7    Amendments.    In the case of Hydrocarbon, amend its
certificate of incorporation or bylaws.

        Section 4.8    Accounting Methods.    Implement or adopt any material
change in its accounting principles, practices or methods, other than as may be
required by law or generally accepted accounting principles.

18

--------------------------------------------------------------------------------

        Section 4.9    Insurance.    Fail to use commercially reasonable best
efforts to maintain with financially responsible insurance companies, insurance
in such amounts and against such risks and losses as has been customarily
maintained by it in the past.

        Section 4.10    Taxes.    

        (a)   Make or rescind any material express or deemed election relating
to Taxes unless it is reasonably expected that such action will not materially
and adversely affect it, including elections for any and all joint ventures,
partnerships, limited liability companies, working interests or other
investments where it has the capacity to make such binding election;

        (b)   settle or compromise any material claim, action, suit, litigation,
proceeding, arbitration, investigation, audit or controversy relating to Taxes,
except where such settlement or compromise will not materially and adversely
affect it; or

        (c)   change in any material respect any of its methods of reporting
income, or deductions for federal income tax purposes from those employed in the
preparation of its federal income tax return for the most recent taxable year
for which a return has been filed, except as may be required by applicable law
or except for such changes that are reasonably expected not to materially
adversely affect it.

        Section 4.11    Debt, Capital Expenditures and the Like.    In the case
of Hydrocarbon, except as provided in Schedule 4.11, (a) incur any indebtedness
for borrowed money (except for working capital under existing credit facilities
or equipment financing arrangements) or guarantee any such indebtedness of
others, (b) enter into any material lease (whether operating or capital),
(c) create any Lien on the property of Hydrocarbon or such Subsidiaries in
connection with any pre-existing indebtedness, new indebtedness or lease (other
than as permitted by clauses (a) and (b) of this Section 4.11), or (d) make or
commit to make aggregate capital expenditures in excess of $5.0 million.

        Section 4.12    No Dissolution.    Authorize, recommend, propose or
announce an intention to adopt a plan of complete or partial dissolution or
liquidation.

        Section 4.13    Adverse Actions.    Knowingly take any action that is
intended or is reasonably likely to result in (a) any of its representations and
warranties set forth in this Agreement being or becoming untrue (taking into
account the standard in Section 5.2) at any time prior to the Closing, (b) any
of the conditions to the Redemption and Merger set forth in Article VII not
being satisfied, (c) any material delay or prevention of the consummation of the
Redemption and Merger or (d) a material violation of any provision of this
Agreement except, in each case, as may be required by applicable law.

        Section 4.14    Agreements.    Agree or commit to do anything prohibited
by Sections 4.1 through 4.13.

ARTICLE V

REPRESENTATIONS AND WARRANTIES

        Section 5.1    Disclosure Schedule.    On or prior to the date hereof,
Energy Partners has delivered to Hydrocarbon and Hydrocarbon has delivered to
Energy Partners a schedule (respectively, its "Disclosure Schedule") setting
forth, among other things, items the disclosure of which is necessary or
appropriate in relation to any or all of its representations and warranties;
provided, however, that (a) no such item is required to be set forth in a
Disclosure Schedule as an exception to a representation or warranty if its
absence is not reasonably likely to result in the related representation or
warranty being deemed untrue or incorrect under the standard established by
Section 5.2, and (b) the mere inclusion of an item in a Disclosure Schedule
shall not be deemed an admission by a party that such item represents a material
exception or fact, event or circumstance or that such item is reasonably likely
to result in a Material Adverse Effect.

19

--------------------------------------------------------------------------------

        Section 5.2    Standard.    No representation or warranty of Energy
Partners or Hydrocarbon contained in Section 5.3 (except Sections 5.3(b),
5.3(c)(i), 5.3(c)(ii), 5.3(d) and 5.3(e)) shall be deemed untrue or incorrect,
and no party hereto shall be deemed to have breached a representation or
warranty, as a consequence of the existence of any fact, circumstance or event
unless such fact, circumstance or event, individually or taken together with all
other facts, circumstances or events inconsistent with any paragraph of
Section 5.3, has had or is reasonably expected to have a Material Adverse
Effect.

        Section 5.3    Representations and Warranties.    Subject to Sections
5.1 and 5.2 and except as Previously Disclosed or (other than with respect to
Sections 5.3(a) and (b)) as set forth in its SEC Documents filed and publicly
available prior to the date hereof (excluding any disclosures included therein
to the extent they are cautionary, predictive or forward-looking in nature,
including those in any risk factor section of such documents), Hydrocarbon
hereby represents and warrants to Energy Partners, and Energy Partners hereby
represents and warrants to Hydrocarbon, to the extent applicable, in each case
with respect to itself and its Subsidiaries, as follows:

        (a)    Organization, Standing and Authority.    Such party is a
corporation, or in the case of Energy Partners, a limited partnership, duly
organized, validly existing and in good standing under the laws of the
jurisdiction of its organization. Such party (i) is duly qualified to do
business and is in good standing in the states of the United States where its
ownership or leasing of property or the conduct of its business requires it to
be so qualified and (ii) has in effect all federal, state, local, and foreign
governmental authorizations and permits necessary for it to own or lease its
properties and assets and to carry on its business as it is now conducted.

        (b)    Shares.    

        (i)    In the case of Hydrocarbon, as of the date hereof, the authorized
capital stock of Hydrocarbon consists of 20,000,000 shares of Common Stock,
$0.01 par value, of which 12,001,151 shares are issued and outstanding, and
5,000,000 shares of Preferred Stock, no shares of which are issued and
outstanding. Such outstanding shares were duly authorized and are validly issued
and fully paid and non-assessable and are not subject to any preemptive or
similar rights (and were not issued in violation of any preemptive or similar
rights).

        (ii)   In the case of Energy Partners, as of the date hereof, there are
36,500,445 Common Units and no Subordinated Units issued and outstanding, and
all of such Common Units and Subordinated Units and the limited partner
interests represented thereby were duly authorized and validly issued in
accordance with the Partnership Agreement and are fully paid (to the extent
required under the Partnership Agreement) and nonassessable (except as such
nonassessability may be affected by Sections 17-303, 17-607 and 17-804 of the
Delaware LP Act). As of the date hereof, the General Partner owns a 2% general
partner interest in Energy Partners and all of the IDRs, and such general
partner interest was duly authorized and validly issued in accordance with the
Partnership Agreement. The Common Units to be issued in the Merger will be duly
authorized and validly issued in accordance with the Amended and Restated
Partnership Agreement and will be fully paid (to the extent required under the
Amended and Restated Partnership Agreement) and nonassessable (except as such
nonassessability may be affected by Sections 17-303, 17-607 and 17-804 of the
Delaware LP Act).

        (iii)  As of the date hereof, except as Previously Disclosed in
Schedule 5.3(b) of a party's Disclosure Schedule, there are no shares of capital
stock (in the case of Hydrocarbon) or interests (in the case of Energy Partners)
of such party's equity securities authorized and reserved for issuance, such
party does not have any Rights issued or outstanding with respect to its equity
securities, and such party does not have any commitment to authorize, issue or
sell any such equity securities or Rights, except pursuant to this Agreement.
Since December 31, 2006, Hydrocarbon has not issued any shares of its capital
stock or rights in respect thereof or reserved any shares for

20

--------------------------------------------------------------------------------

such purposes except pursuant to plans or commitments Previously Disclosed in
Schedule 5.3(b) of its Disclosure Schedule.

        (iv)  The number of shares of Hydrocarbon Common Stock which are
issuable and reserved for issuance upon exercise of Hydrocarbon Stock Options as
of the date hereof are Previously Disclosed in Schedule 5.3(b) of Hydrocarbon's
Disclosure Schedule, and the number of Common Units that are issuable upon
vesting of phantom units or exercise of any employee or director options to
purchase Common Units as of the date hereof are Previously Disclosed in
Schedule 5.3(b) of Energy Partners' Disclosure Schedule.

        (c)    Subsidiaries.    

        (i)    (A) Such party has Previously Disclosed in Schedule 5.3(c) of its
Disclosure Schedule a list of all of its Subsidiaries together with the
jurisdiction of organization of each such Subsidiary, (B) it owns, directly or
indirectly, all of the equity interests of each of its Subsidiaries, except as
Previously Disclosed in Schedule 5.3(c) of a party's Disclosure Schedule, (C) no
equity interests of any of its Subsidiaries are or may become required to be
issued by reason of any Rights, (D) there are no contracts, commitments,
understandings or arrangements by which any of such Subsidiaries is or may be
bound to sell or otherwise transfer any equity interests of any such
Subsidiaries, (E) there are no contracts, commitments, understandings, or
arrangements relating to its rights to vote or to dispose of such equity
interests, and (F) all of the equity interests of each such Subsidiary held by
it or its Subsidiaries are fully paid and nonassessable and are owned by it or
its Subsidiaries free and clear of any Liens.

        (ii)   In the case of the representations and warranties of Hydrocarbon,
other than ownership of its Subsidiaries, Hydrocarbon does not own beneficially,
directly or indirectly, any equity securities or similar interests of any
person, or any interest in a partnership or joint venture of any kind, except as
disclosed in Schedule 5.3(c)(ii).

        (iii)  Each of such party's Subsidiaries has been duly organized and is
validly existing in good standing under the laws of the jurisdiction of its
organization and (A) is duly qualified to do business and in good standing in
the jurisdictions where its ownership or leasing of property or the conduct of
its business requires it to be so qualified and (B) has in effect all federal,
state, local, and foreign governmental authorizations and permits necessary for
it to own or lease its properties and assets and to carry on its business as it
is now conducted.

        (d)    Corporate or Partnership Power.    Such party and each of its
Subsidiaries has the corporate power and authority, or in the case of Energy
Partners the partnership power and authority, to carry on its business as it is
now being conducted and to own all its properties and assets; and it has the
corporate power and authority or, in the case of Energy Partners, the
partnership power and authority, to execute, deliver and perform its obligations
under this Agreement and to consummate the transactions contemplated hereby.

        (e)    Equityholder Authority.    In the case of this Agreement, subject
to Hydrocarbon Stockholder Approval in the case of Hydrocarbon and Energy
Partners Unitholder Approval in the case of Energy Partners, this Agreement and
the transactions contemplated hereby have been authorized by all necessary
corporate action (partnership action in the case of Energy Partners and limited
liability company action in the case of MergerCo), and this Agreement has been
duly executed and delivered and is a legal, valid and binding agreement of it,
enforceable in accordance with its terms (except as such enforceability may be
limited by applicable bankruptcy, insolvency, reorganization, moratorium,
fraudulent transfer and similar laws of general applicability relating to or
affecting creditors' rights or by general equity principles).

        (f)    No Defaults.    Subject to receipt of the HSR approval, and the
approval of Hydrocarbon's bank group, the declaration of effectiveness of the
Registration Statement, required filings under

21

--------------------------------------------------------------------------------

federal and state securities laws and the NYSE, and the approvals contemplated
by Article VII, the execution, delivery and performance of this Agreement and
the consummation of the transactions contemplated hereby do not and will not
(i) constitute a breach or violation of, or result in a default (or an event
that, with notice or lapse of time or both, would become a default) under, or
result in the termination or in a right of termination or cancellation of, or
accelerate the performance required by, any note, bond, mortgage, indenture,
deed of trust, license, franchise, lease, contract, agreement, joint venture or
other instrument or obligation to which it or any of its Subsidiaries is a party
or by which it or any of its Subsidiaries or properties is subject or bound,
(ii) constitute a breach or violation of, or a default under, in the case of
Hydrocarbon its certificate of incorporation or bylaws and in the case of Energy
Partners its Partnership Agreement or MergerCo's operating agreement,
(iii) contravene or conflict with or constitute a violation of any provision of
any law, rule, regulation, judgment, order or decree binding upon or applicable
to it or any of its Subsidiaries, (iv) result in the creation of any Lien on any
of its assets or its Subsidiaries' assets other than in connection with any
indebtedness obtained in connection with the transactions contemplated by this
Agreement, or (v) cause the transactions contemplated by this Agreement to be
subject to Takeover Laws.

        (g)    Financial Reports and SEC Documents.    Its annual report on
Form 10-K for the fiscal year ended December 31, 2006, and all other reports,
registration statements, definitive proxy statements or information statements
filed or to be filed by it or any of its Subsidiaries subsequent to December 31,
2004 under the Securities Act, or under Sections 13(a), 13(c), 14 and 15(d) of
the Exchange Act, in the form filed, or to be filed (collectively, its "SEC
Documents"), with the SEC (i) complied or will comply in all material respects
as to form with the applicable requirements under the Securities Act or the
Exchange Act, as the case may be, and (ii) did not and will not contain any
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements made therein, in light of
the circumstances under which they were made, not misleading; and each of the
balance sheets contained in or incorporated by reference into any such SEC
Document (including the related notes and schedules thereto) fairly presents the
financial position of the entity or entities to which it relates as of its date,
and each of the statements of income and changes in stockholders' equity and
cash flows or equivalent statements in the case of Energy Partners in such SEC
Documents (including any related notes and schedules thereto) fairly presents
the results of operations, changes in stockholders' equity and changes in cash
flows, as the case may be, of the entity or entities to which it relates for the
periods to which it relates, in each case in accordance with generally accepted
accounting principles consistently applied during the periods involved, except
in each case as may be noted therein, subject to normal year-end audit
adjustments in the case of unaudited statements. Except as and to the extent set
forth on its balance sheet as of December 31, 2006, as of such date, neither it
nor any of its Subsidiaries had any liabilities or obligations of any nature
(whether accrued, absolute, contingent or otherwise) that would be required to
be reflected on, or reserved against in, a balance sheet or in the notes thereto
prepared in accordance with generally accepted accounting principles
consistently applied.

        (h)    Litigation; Regulatory Action.    

        (i)    No litigation, claim or other proceeding before any court or
governmental agency is pending against it or any of its Subsidiaries and, to the
best of its knowledge, no such litigation, claim or other proceeding has been
threatened, other than normal and routine litigation which is either covered by
insurance in amounts sufficient to discharge any likely exposure. There are no
outstanding judgments, decrees, injunctions, awards or orders against it or any
of its Subsidiaries. Schedule 5.3(h) of its Disclosure Schedule contains, as of
the date of this Agreement, an accurate and complete list of all actions, suits
and proceedings pending or, to the best of its knowledge, threatened against it,
except as to routine law suits arising in the ordinary course of business which
are fully covered by insurance (except for deductible amounts under such
insurance policies which if required to be paid would not individually or in the
aggregate have a Material Adverse Effect).

22

--------------------------------------------------------------------------------

        (ii)   Neither it nor any of its Subsidiaries or properties is a party
to or is subject to any order, decree, agreement, memorandum of understanding or
similar arrangement with, or a commitment letter or similar submission to, any
federal or state governmental agency or court or authority or body or the
supervision or regulation of it or any of its Subsidiaries (collectively, the
"Regulatory Authorities").

        (iii)  Neither it nor any of its Subsidiaries has been advised by any
Regulatory Authority that such Regulatory Authority is contemplating issuing or
requesting (or is considering the appropriateness of issuing or requesting) any
such order, decree, agreement, memorandum of understanding, commitment letter or
similar submission.

        (i)    Compliance with Laws.    Except as set forth in Schedule 5.3(i)
of its Disclosure Schedule, it and each of its Subsidiaries:

        (i)    in the conduct of its business, is in compliance with all
applicable federal, state, local and foreign statutes, laws, regulations,
ordinances, rules, judgments, orders or decrees applicable thereto or to the
employees conducting such businesses, (any instance of failure to so comply is
referred to herein as a "Non-Compliance Event");

        (ii)   has all permits, licenses, authorizations, orders and approvals
of, and has made all filings, applications and registrations with, all
Regulatory Authorities that are required in order to permit it to conduct its
businesses substantially as presently conducted; all such permits, licenses,
certificates of authority, orders and approvals are in full force and effect
and, to the best of its knowledge, no suspension or cancellation of any of them
is threatened (any instance or failure to obtain any of the foregoing and to
maintain them in full force and effect is referred to herein as a "Permitting
Violation"); and

        (iii)  has not received, since December 31, 2004, any notification or
communication from any Regulatory Authority asserting that it or any of its
Subsidiaries is not in compliance with any of the statutes, regulations, or
ordinances which such Regulatory Authority enforces or threatening to revoke any
license, franchise, permit, or governmental authorization nor, to its knowledge,
do any grounds for any of the foregoing exist (any instance of the foregoing
referred to herein as a "Non-Compliance Notification").

        (j)    Defaults.    Neither it nor any of its Subsidiaries is in default
under any contract, agreement, commitment, arrangement, lease, insurance policy,
or other instrument to which it is a party, by which its respective assets,
business, or operations may be bound or affected, or under which it or its
respective assets, business, or operations receives benefits, and there has not
occurred any event that, with the lapse of time or the giving of notice or both,
would constitute such a default.

        (k)    No Brokers.    No action has been taken by it that would give
rise to any valid claim against any party hereto for a brokerage commission,
finder's fee or other like payment with respect to the transactions contemplated
by this Agreement, excluding, in the case of Hydrocarbon, fees to be paid to
Merrill Lynch, Pierce, Fenner & Smith Incorporated, and, in the case of Energy
Partners, fees to be paid to Lehman Brothers Inc. and RBC Capital Markets, in
every case pursuant to letter agreements which have been heretofore disclosed to
the other party.

        (l)    Compensation and Benefit Plans.    

        (i)    Schedule 5.3(l)(i) of a party's Disclosure Schedule contains a
complete list of all material bonus, vacation, deferred compensation, pension,
retirement, profit-sharing, thrift, savings, employee stock ownership, stock
bonus, stock purchase, restricted stock and stock option plans, all employment
or severance contracts, all medical, dental, disability, health and life
insurance plans, all other employee benefit and fringe benefit plans, contracts
or arrangements and any applicable "change of control" or similar provisions in
any plan, contract or arrangement maintained or

23

--------------------------------------------------------------------------------

contributed to by it or any of its Subsidiaries for the benefit of officers,
former officers, employees, former employees, directors, former directors, or
the beneficiaries of any of the foregoing, including all "employee benefit
plans" as defined in ERISA Section 3(3) (collectively, "Compensation and Benefit
Plans").

        (ii)   True and complete copies of its Compensation and Benefit Plans,
including, but not limited to, any trust instruments and/or insurance contracts,
if any, forming a part thereof, and all amendments thereto and, if applicable,
the most recent Form 5500 and annual reports for such plans have been made
available to the other party.

        (iii)  Each of its Compensation and Benefit Plans has been administered
in all material respects in accordance with the terms thereof. All "employee
benefit plans" within the meaning of Section 3(3) of ERISA, other than
"multiemployer plans" within the meaning of Section 3(37) of ERISA
("Multiemployer Plans"), covering employees or former employees of it and its
Subsidiaries (its "Plans"), to the extent subject to ERISA, are in material
compliance with ERISA, the Code, and other applicable laws and, to the knowledge
of Hydrocarbon, no prohibited transaction has occurred with respect to any such
employee benefit plan that would result in any material excise Tax or other
material liability under ERISA or the Code. Each Compensation and Benefit Plan
of it or its Subsidiaries which is an "employee pension benefit plan" within the
meaning of Section 3(2) of ERISA ("Pension Plan") and which is intended to be
qualified under Section 401(a) of the Code has received a favorable
determination letter from the Internal Revenue Service or may rely on an opinion
letter from the Internal Revenue Service, and it is not aware of any
circumstances reasonably likely to result in the revocation or denial of any
such favorable determination or opinion letter. There is no pending or, to its
knowledge, threatened litigation or governmental audit, examination or
investigation relating to any of the Compensation and Benefit Plans (other than
regular claims for benefits).

        (iv)  No material liability under Title IV of ERISA has been or is
expected to be incurred by it or any of its Subsidiaries with respect to any
ongoing, frozen or terminated "single-employer plan," within the meaning of
Section 4001(a)(15) of ERISA, currently or formerly maintained by any of them,
or the single-employer plan of any entity which is considered one employer with
it under Section 4001(a)(15) of ERISA or Section 414 of the Code (an "ERISA
Affiliate"). Neither it nor any of its Subsidiaries presently contributes to a
Multiemployer Plan, nor have they contributed to such a plan within the past
five calendar years. No Pension Plan is a "defined benefit plan" within the
meaning of ERISA Section 3(35) or "money purchase" plan subject to Section 412
of the Code.

        (v)   All contributions, premiums and payments required to be made under
the terms of any Compensation and Benefit Plan of it or any of its Subsidiaries
have been made.

        (vi)  Neither it nor any of its Subsidiaries has any obligations under
any Compensation and Benefit Plans to provide benefits, including death or
medical benefits, with respect to employees of it or its Subsidiaries beyond
their retirement or other termination of service other than (A) coverage
mandated by Part 6 of Title I of ERISA or Section 4980B of the Code,
(B) retirement or death benefits under any employee pension benefit plan (as
defined under Section 3(2) of ERISA), (C) disability benefits under any employee
welfare plan that have been fully provided for by insurance or otherwise, or
(D) benefits in the nature of severance pay.

        (vii) Except as Previously Disclosed under Schedule 5.3(l)(vii) of a
party's Disclosure Schedule, neither the execution and delivery of this
Agreement nor the consummation of the transactions contemplated hereby will
(A) result in any payment (including, without limitation, severance,
unemployment compensation, golden parachute or otherwise) becoming due to any
director or any employee of it or any of its Subsidiaries under any Compensation
and Benefit Plan or otherwise from it or any of its Subsidiaries, (B) increase
any benefits otherwise payable under any Compensation and Benefit Plan or
(C) result in any acceleration of the time of payment or vesting of any such
benefit.

24

--------------------------------------------------------------------------------

        (m)    Labor Matters.    Except as set forth in Schedule 5.3(m) of a
party's Disclosure Schedule, neither it nor any of its Subsidiaries is a party
to, or is bound by, any collective bargaining agreement, contract or other
agreement or understanding with a labor union or labor organization, nor is it
or any of its Subsidiaries the subject of a proceeding asserting that it or any
such Subsidiaries has committed an unfair labor practice (within the meaning of
the National Labor Relations Act) or seeking to compel it or such Subsidiaries
to bargain with any labor organization as to wages and conditions of employment.

        (n)    Environmental Matters.    Except as Previously Disclosed under
Schedule 5.3(n) of a party's Disclosure Schedule, neither (i) the past or
present conduct nor operation of such party or its Subsidiaries nor any
condition of any property or asset presently or previously owned, leased or
operated by any of them, including but not limited to on-site or off-site
disposal or release of any chemical substance, product or waste, violates or
violated Environmental Laws, and no condition has existed or event has occurred
with respect to any of them or any such property that, with notice or the
passage of time, or both, is reasonably likely to result in liability or
obligations for any clean-up, remediation, disposal or corrective action under
Environmental Laws or claims for personal injury, property damage or damage to
natural resources, and (ii) such party nor any of its Subsidiaries has received
any notice from any person or entity that it or its Subsidiaries or the
operation or condition of any property or asset ever owned, leased, operated,
held as collateral or held as a fiduciary by any of them is or was in violation
of or otherwise are alleged to have liability under any Environmental Law or has
entered into any consent decree or order or is subject to any order of any court
or governmental authority or tribunal under any Environmental Law or relating to
the clean-up of any hazardous materials contamination, including, but not
limited to, responsibility (or potential responsibility) for the cleanup or
other remediation of any pollutants, contaminants, or hazardous or toxic wastes,
substances or materials at, on, beneath, or originating from any such property.

        (o)    Tax Matters.    

        (i)    All material returns, declarations, reports, estimates,
information returns and statements required to be filed under federal, state,
local or any foreign Tax Laws ("Tax Returns") with respect to it or any of its
Subsidiaries, have been timely filed, or requests for extensions have been
timely filed and have not expired;

        (ii)   all Tax Returns filed by it are complete and accurate in all
material respects;

        (iii)  all Taxes shown to be due on such Tax Returns and all other
Taxes, if any, required to be paid by it or its Subsidiaries for all periods
ending through the date hereof have been paid or adequate reserves have in
accordance with generally accepted accounting principles been established for
the payment of such Taxes; and

        (iv)  no material (A) audit or examination or (B) refund litigation with
respect to any Tax Return is pending. As of the date hereof, neither it nor any
of its Subsidiaries (x) has granted any requests, agreements, consents or
waivers to extend the statutory period of limitations applicable to the
assessment of any Taxes with respect to any Tax Returns, (y) is a party to any
Tax sharing or Tax indemnity agreement or (z) is a party to an agreement that
provides for the payment of any amount that would constitute a "parachute
payment" within the meaning of Section 280G of the Code.

        (p)    Regulatory Approvals.    Except as set forth in Schedule 5.3(p)
of a party's Disclosure Schedule, the only approval of any governmental agency
necessary to consummate the transactions contemplated by this Agreement (other
than filings under the Securities Act) is pursuant to the HSR. As of the date
hereof, neither Hydrocarbon nor the Energy Partners is aware of any reason why
the approvals under the HSR will not be received.

25

--------------------------------------------------------------------------------

        (q)    No Material Adverse Change.    Except as disclosed in its SEC
Documents filed with the SEC on or before the date hereof, since December 31,
2006, (i) it and its Subsidiaries have conducted their respective businesses in
the ordinary and usual course (excluding the incurrence of expenses related to
this Agreement and the transactions contemplated hereby), (ii) it has not made
any material change in its accounting methods, principles or practices or its
Tax methods, practices or elections and (iii) no event has occurred or
circumstance arisen that, individually or taken together with all other facts,
circumstances and events is reasonably likely to result in a Material Adverse
Effect.

        (r)    Insurance.    It has previously delivered to the other party a
schedule listing the officers' and directors' liability insurance policies,
primary and excess casualty and liability insurance policies providing coverage
for bodily injury and property damage maintained by it and its Subsidiaries. It
and its Subsidiaries maintain insurance coverage reasonably adequate for the
operation of their respective businesses taking into account the cost and
availability of such insurance.

        (s)    Condition and Sufficiency of Assets.    The assets used in the
business of it and its Subsidiaries are in operating condition and repair
consistent with normal industry standards and are adequate for the uses to which
they are being put and none of such assets are in need of replacement,
maintenance or repairs except for ordinary and routine maintenance and repairs
that are not material in nature or cost, except for assets which are not in
service and the use of which are not required to conduct the business of it and
its Subsidiaries in the ordinary course consistent with past practices. The
assets in service are sufficient for the continued conduct of its business after
the Closing.

        (t)    Intellectual Property.    Except as may be disclosed in
Schedule 5.3(t) of its Disclosure Schedule, it and its Subsidiaries own or
possess adequate licenses and other valid rights to use all patents, patent
rights, trademarks, trademark rights and proprietary information used or held
for use in connection with their respective businesses as currently being
conducted, and there are no assertions or claims challenging the validity of any
of the foregoing.

        (u)    The Hydrocarbon Board Recommendations.    At a meeting duly
called and held, the Deal Committee determined that this Agreement and the
transactions contemplated hereby, including the adoption of the Redemption
Charter Amendment, are fair to and in the best interests of the Unaffiliated
Stockholders, and recommended that the Hydrocarbon Board approve the Redemption
Charter Amendment, this Agreement and the transactions contemplated hereby,
declare the Redemption Charter Amendment and the Agreement advisable and
recommend their adoption by the stockholders of Hydrocarbon. At a meeting duly
called and held, the Hydrocarbon Board has approved and declared the
advisability of, and resolved to recommend that its stockholders approve the
Redemption Charter Amendment and adopt this Agreement. Hydrocarbon has taken all
necessary actions to render the restrictions on "business combinations" (as
defined in Section 203 of the DGCL) inapplicable to this Agreement and the
transactions contemplated herby and thereby.

        (v)    The Board of Directors of the General Partner
Recommendations.    At a meeting duly called and held, the Conflicts Committee
determined that this Agreement and the transactions contemplated hereby,
including the Unit Issuance and the adoption of the Amended and Restated
Partnership Agreement, are fair and reasonable to, and in the best interests of,
the Unaffiliated Common Unitholders and the Partnership, and recommended that
the Board of Directors of the General Partner approve this Agreement and the
transactions contemplated hereby and recommend to the Unaffiliated Common
Unitholders that they approve the Merger, the Unit Issuance and the Amended and
Restated Partnership Agreement. At a meeting duly called and held, the Board of
Directors of the General Partner has approved and declared the advisability of,
and resolved to recommend that the unitholders of Energy Partners approve the
Merger, the Unit Issuance and the Amended and Restated Partnership Agreement.

        (w)    Operations of MergerCo.    In the case of Energy Partners,
MergerCo was formed solely for the purpose of engaging in the transactions
contemplated by this Agreement and has engaged in no

26

--------------------------------------------------------------------------------

business other than in connection with entering into this Agreement and engaging
in the transactions contemplated hereby.

        (x)    Hydrocarbon Fairness Opinion.    Merrill Lynch, Pierce, Fenner &
Smith Incorporated has delivered to the Deal Committee its written opinion dated
as of the date hereof, that as of such date, the Redemption/Merger Consideration
is fair, from a financial point of view, to the Unaffiliated Stockholders, a
copy of which has been provided to Energy Partners.

        (y)    Energy Partners Fairness Opinion.    Lehman Brothers Inc. has
delivered to the Conflicts Committee its written opinion dated as of the date
hereof, that as of such date, the Redemption/Merger Consideration paid in the
Redemption and the Merger and the consideration paid for the Class B membership
interests in the General Partner pursuant to the Class B Membership Interest
Contribution Agreement, in the aggregate, are fair, from a financial point of
view, to the holders of the Common Units (other than Hydrocarbon and its
affiliates), a copy of which has been provided to the Hydrocarbon Board.

ARTICLE VI

COVENANTS

        Hydrocarbon hereby covenants to and agrees with Energy Partners, and
Energy Partners hereby covenants to and agrees with Hydrocarbon, that:

        Section 6.1    Best Efforts.    Subject to the terms and conditions of
this Agreement, it shall use its commercially reasonable best efforts in good
faith to take, or cause to be taken, all actions, and to do, or cause to be
done, all things necessary, proper, desirable or advisable under applicable
laws, so as to permit consummation of the Redemption and Merger promptly and
otherwise to enable consummation of the transactions contemplated hereby,
including, without limitation, obtaining (and cooperating with the other party
hereto to obtain) HSR approval and any other third party approval that is
required to be obtained by Hydrocarbon or Energy Partners or any of their
respective Subsidiaries in connection with the Redemption and/or Merger and the
other transactions contemplated by this Agreement, and using commercially
reasonable best efforts to lift or rescind any injunction or restraining order
or other order adversely affecting the ability of the parties to consummate the
transactions contemplated hereby, and using commercially reasonable best efforts
to defend any litigation seeking to enjoin, prevent or delay the consummation of
the transactions contemplated hereby or seeking material damages, and each shall
cooperate fully with the other parties hereto to that end, and shall furnish to
the other party copies of all correspondence, filings and communications between
it and its Affiliates and any Regulatory Authority with respect to the
transactions contemplated hereby. In complying with the foregoing, neither it
nor its Subsidiaries shall be required to take measures that would have a
Material Adverse Effect on it and such Subsidiaries taken as a whole.

        Section 6.2    Equityholder Approvals.    Subject to the terms and
conditions of this Agreement, each of them shall take, in accordance with
applicable law, applicable stock exchange rules and its certificate of
incorporation and bylaws, in the case of Hydrocarbon, and the Partnership
Agreement, in the case of Energy Partners, all action necessary to call, hold
and convene, respectively, (i) an appropriate meeting of stockholders of
Hydrocarbon to consider and vote upon the approval of the Redemption Charter
Amendment, the Merger, the adoption of this Agreement and any other matters
required to be approved by Hydrocarbon's stockholders for consummation of the
Redemption and Merger (including any adjournment or postponement, the
"Hydrocarbon Meeting") and (ii) an appropriate meeting of the holders of the
Common Units to consider and vote upon the approval of the Merger, the Unit
Issuance and the Amended and Restated Partnership Agreement, and any other
matters required to be approved by them for consummation of the Merger
(including any adjournment or postponement, the "Energy Partners Meeting"; and
each of the Hydrocarbon Meeting and Energy Partners Meeting, a "Meeting"),
respectively, promptly after the date hereof. Subject to Section 6.6(c), the
Hydrocarbon

27

--------------------------------------------------------------------------------

Board and the Deal Committee shall recommend such approval (the "Hydrocarbon
Recommendation"), and each of Energy Partners and Hydrocarbon shall take all
reasonable lawful action to solicit such approval by its respective equity
holders. The Board of Directors of the General Partner and the Conflicts
Committee shall recommend approval of the Merger, the Unit Issuance and the
Amended and Restated Partnership Agreement to its holders of Common Units (the
"Energy Partners Recommendation"). Notwithstanding the foregoing, at any time
prior to obtaining Energy Partners Unitholder Approval, the Board of Directors
of the General Partner and the Conflicts Committee may withdraw, modify or
qualify in any manner adverse to Hydrocarbon the Energy Partners Recommendation
(any such action being referred to as a "Energy Partners Change in
Recommendation") if they have concluded in good faith, after consultation with,
and taking into account the advice of their outside legal advisors and financial
consultants, that an Energy Partners Change in Recommendation is necessary to
comply with their fiduciary duties under applicable law. The obligation of
Hydrocarbon to call, hold and convene the Hydrocarbon Meeting shall not be
affected by a Hydrocarbon Change in Recommendation, and the obligation of Energy
Partners to call, hold and convene the Energy Partners Meeting shall not be
affected by an Energy Partners Change in Recommendation.

        Section 6.3    Registration Statement.    

        (a)   Each of Energy Partners and Hydrocarbon agrees to cooperate in the
preparation of a registration statement on Form S-4 (the "Registration
Statement") (including the joint proxy statement and prospectus and other proxy
solicitation materials of Energy Partners and Hydrocarbon constituting a part
thereof (the "Joint Proxy Statement") and all related documents) to be filed by
Energy Partners with the SEC in connection with the issuance of Common Units in
the Merger as contemplated by this Agreement. Each of Energy Partners and
Hydrocarbon agrees that the other party shall have the right to consent to the
disclosure to be contained in the Registration Statement and the Joint Proxy
Statement. Provided Hydrocarbon has cooperated as required above, Energy
Partners agrees to file the Registration Statement with the SEC as promptly as
practicable. Each of Hydrocarbon and Energy Partners agrees to use all
commercially reasonable best efforts to cause the Registration Statement to be
declared effective under the Securities Act as promptly as practicable after
filing thereof. Energy Partners also agrees to use commercially reasonable best
efforts to obtain all necessary state securities law or "Blue Sky" permits and
approvals required to carry out the transactions contemplated by this Agreement.
Hydrocarbon agrees to furnish to Energy Partners all information concerning
Hydrocarbon, its Subsidiaries (other than Energy Partners and its Subsidiaries),
officers, directors and stockholders and to take such other action as may be
reasonably requested in connection with the foregoing.

        (b)   Each of Hydrocarbon and Energy Partners agrees, as to itself and
its Subsidiaries, other than, in the case of Hydrocarbon, Energy Partners and
its Subsidiaries, that (i) none of the information supplied or to be supplied by
it for inclusion or incorporation by reference in the Registration Statement
will, at the time the Registration Statement and each amendment or supplement
thereto, if any, becomes effective under the Securities Act, contain any untrue
statement of a material fact or omit to state any material fact required to be
stated therein or necessary to make the statements therein, in light of the
circumstances under which they were made, not misleading, and (ii) the Joint
Proxy Statement and any amendment or supplement thereto will, at the date of
mailing to stockholders and at the times of the Energy Partners Meeting and
Hydrocarbon Meeting, not contain any untrue statement of a material fact or omit
to state any material fact required to be stated therein or necessary to make
the statements therein, in light of the circumstances under which they were
made, not misleading. Each of Hydrocarbon and Energy Partners further agrees
that if it shall become aware prior to the Closing Date of any information that
would cause any of the statements in the Registration Statement to be false or
misleading with respect to any material fact, or omit to state any material fact
necessary to make the statements therein, in light of the circumstances under
which they were made,

28

--------------------------------------------------------------------------------

not false or misleading, it will promptly inform the other party thereof and
take the necessary steps to correct such information in an amendment or
supplement to the Registration Statement.

        (c)   Energy Partners will advise Hydrocarbon, promptly after Energy
Partners receives notice thereof, of the time when the Registration Statement
has become effective or any supplement or amendment has been filed, of the
issuance of any stop order or the suspension of the qualification of the Common
Units for offering or sale in any jurisdiction, of the initiation or threat of
any proceeding for any such purpose, or of any request by the SEC for the
amendment or supplement of the Registration Statement or for additional
information.

        (d)   Each of Energy Partners and Hydrocarbon will use its commercially
reasonable best efforts to cause the Joint Proxy Statement to be mailed to its
unitholders and stockholders, respectively, as soon as practicable after the
effective date of the Registration Statement.

        Section 6.4    Press Releases.    Each of Hydrocarbon and Energy
Partners will not, without the prior approval of the Conflicts Committee in the
case of Hydrocarbon and the Deal Committee in the case of Energy Partners, issue
any press release or written statement for general circulation relating to the
transactions contemplated hereby, except as otherwise required by applicable law
or regulation or the rules of the NYSE (and the American Stock Exchange as
applicable), in which case it will consult with the other party before issuing
any such press release or written statement.

        Section 6.5    Access; Information.    

        (a)   Upon reasonable notice and subject to applicable laws relating to
the exchange of information, each party shall, and shall cause its Subsidiaries
to, afford the other parties and their officers, employees, counsel, accountants
and other authorized representatives, access, during normal business hours
throughout the period prior to the Effective Time, to all of its properties,
books, contracts, commitments and records, and to its officers, employees,
accountants, counsel or other representatives, and, during such period, it
shall, and shall cause its Subsidiaries to, furnish promptly to such other
parties and its representatives (i) a copy of each material report, schedule and
other document filed by it pursuant to the requirements of federal or state
securities law (other than reports or documents that Hydrocarbon or Energy
Partners or their respective Subsidiaries, as the case may be, are not permitted
to disclose under applicable law) and (ii) all other information concerning the
business, properties and personnel of it as the other may reasonably request.
Neither Hydrocarbon nor Energy Partners nor any of their respective Subsidiaries
shall be required to provide access to or to disclose information where such
access or disclosure would violate or prejudice the rights of its customers,
jeopardize the attorney-client privilege of the institution in possession or
control of such information or contravene any law, rule, regulation, order,
judgment, decree, fiduciary duty or binding agreement entered into prior to the
date of this Agreement. The parties hereto will make appropriate substitute
disclosure arrangements under the circumstances in which the restrictions of the
preceding sentence apply.

        (b)   Energy Partners will not use any information obtained pursuant to
this Section 6.5 for any purpose unrelated to the consummation of the
transactions contemplated by this Agreement and will hold all information and
documents obtained pursuant to this paragraph in confidence. No investigation by
either party of the business and affairs of the other shall affect or be deemed
to modify or waive any representation, warranty, covenant or agreement in this
Agreement, or the conditions to either party's obligation to consummate the
transactions contemplated by this Agreement.

        Section 6.6    Acquisition Proposals.    

        (a)   Notwithstanding any other provision of this Agreement to the
contrary, during the period beginning on the date of this Agreement and
continuing until the No-Solicitation Period Start Date, Hydrocarbon and its
Representatives shall have the right to, directly or indirectly, (i) initiate,
solicit, facilitate and encourage Acquisition Proposals, (ii) enter into
discussions relating to Acquisition Proposals, (iii) continue or otherwise
participate in any discussions or negotiations regarding any

29

--------------------------------------------------------------------------------

Acquisition Proposal, (iv) furnish to any Person any information or data with
respect to Hydrocarbon, including by way of providing access to non-public
information pursuant to (but only pursuant to an executed confidentiality
agreement no less restrictive than the Confidentiality Agreement); provided that
Hydrocarbon shall promptly provide or make available to Energy Partners any
non-public information concerning Hydrocarbon or any Subsidiary that is provided
or made available to any Person which was not previously provided or made
available to Energy Partners; and (v) otherwise cooperate with or take any other
action to facilitate any proposal that constitutes, or could reasonably be
expected to lead to, an Acquisition Proposal. Within 24 hours following the
No-Solicitation Period Start Date, Hydrocarbon shall notify Energy Partners of
(i) the number of Excluded Parties, (ii) the identity of each Excluded Party and
(iii) the material terms and conditions of each Excluded Party's Acquisition
Proposal and furnish copies of any documents and related correspondence provided
in connection therewith (including any amendments or modifications to any of the
foregoing) received from any Excluded Party. Hydrocarbon shall immediately cease
any discussions with any Person (other than Energy Partners) that are ongoing as
of the No-Solicitation Period Start Date and that constitute an Acquisition
Proposal, except as may be expressly provided for in Sections 6.6(b) and 6.6(c),
and except in respect of any Excluded Party.

        Any Person that submits an Acquisition Proposal that the Deal Committee
and the Hydrocarbon Board determines in good faith constitutes, or could
reasonably be expected to lead to, a Superior Proposal, no later than 24 hours
following the No Solicitation Period Start Date shall be referred to herein as
an "Excluded Party." Notwithstanding anything contained in Section 6.6(a) to the
contrary, any Excluded Party shall cease to be an Excluded Party for all
purposes under this Agreement at such time as the Deal Committee determines in
good faith that the Acquisition Proposal made by such party ceases to be
reasonably likely to lead to a Superior Proposal.

        (b)   Except with respect to any written Acquisition Proposal from an
Excluded Party received after the date hereof and prior to the No-Solicitation
Period Start Date, none of Hydrocarbon and its Subsidiaries shall, and they
shall cause their Representatives not to, directly or indirectly, (i) initiate,
solicit, facilitate or knowingly encourage the submission of, any Acquisition
Proposal, or (ii) participate in any negotiations or negotiations regarding, or
furnish to any person any non-public information with respect to, any
Acquisition Proposal. Notwithstanding anything to the contrary in this
Section 6.6, nothing contained in this Agreement shall prohibit Hydrocarbon from
furnishing any information to, or entering into or participating in discussions
or negotiations with, any person that makes an unsolicited written Acquisition
Proposal which did not result from a breach of this Section 6.6, if (i) the Deal
Committee determines that such Acquisition Proposal constitutes or is likely to
result in a Superior Proposal, and (ii) prior to furnishing such non-public
information to such person, Hydrocarbon receives from such person an executed
confidentiality agreement no less restrictive than the Confidentiality Agreement
and furnishes Energy Partners with any such information that has not previously
been furnished. Any breach of this Section 6.6 by any of Hydrocarbon's or its
Subsidiaries' Representatives shall constitute a breach of this Section 6.6 by
Hydrocarbon.

        (c)   Other than in accordance with Section 6.6(e), and except as
otherwise provided in this Section 6.6(c), neither the Hydrocarbon Board nor any
committee thereof shall (1) (a) withdraw, modify or qualify in any manner
adverse to Energy Partners the Hydrocarbon Recommendation or (b) publicly
approve or recommend, or publicly propose to approve or recommend, any
Acquisition Proposal (any action described in this clause (1) being referred to
as a "Hydrocarbon Change in Recommendation"); or (2) approve, adopt or
recommend, or publicly propose to approve, adopt or recommend, or allow
Hydrocarbon or any of its Subsidiaries to execute or enter into, any letter of
intent, memorandum of understanding, agreement in principle, merger agreement,
acquisition agreement, option agreement, joint venture agreement, partnership
agreement, or other similar contract or any tender or exchange offer providing
for, with respect to, or in connection with, any Acquisition Proposal.
Notwithstanding the foregoing, at any time prior to obtaining the Hydrocarbon
Stockholder

30

--------------------------------------------------------------------------------

Approval, the Deal Committee may make a Hydrocarbon Change in Recommendation if
it shall have concluded in good faith, after consultation with, and taking into
account the advice of, its outside legal advisors and financial consultants, the
Hydrocarbon Change in Recommendation is necessary to comply with its fiduciary
duties under applicable law; provided, however, that the Deal Committee shall
not be entitled to exercise its right to make a Hydrocarbon Change in
Recommendation pursuant to this sentence unless Hydrocarbon has: (x) complied in
all material respects with this Section 6.6, (y) provided to Energy Partners
four calendar days prior written notice (such notice, a "Notice of Proposed
Recommendation Change") advising Energy Partners that the Deal Committee intends
to take such action and specifying the reasons therefor in reasonable detail,
including, if applicable, the terms and conditions of any Superior Proposal that
is the basis of the proposed action and the identity of the Person making the
proposal and contemporaneously providing a copy of all relevant proposed
transaction documents for such Superior Proposal (it being understood and agreed
that any amendment to the terms of any such Superior Proposal shall require a
new Notice of Proposed Recommendation Change and an additional four calendar day
period), and (z) if applicable, provided to Energy Partners all materials and
information delivered or made available to the Person or group of persons making
any Superior Proposal in connection with such Superior Proposal (to the extent
not previously provided). Any Hydrocarbon Change in Recommendation shall not
change the approval of this Agreement or any other approval of the Board of
Directors of Hydrocarbon, including in any respect that would have the effect of
causing any state (including Delaware) corporate takeover statute or other
similar statute to be applicable to the transactions contemplated hereby or
thereby, including the Redemption and/or Merger.

        (d)   In addition to the obligations of Hydrocarbon set forth in this
Section 6.6, Hydrocarbon shall as promptly as practicable (and in any event
within 24 hours after receipt) advise Energy Partners orally and in writing of
any Acquisition Proposal or any matter giving rise to a Hydrocarbon Change in
Recommendation and the material terms and conditions of any such Acquisition
Proposal or any matter giving rise to a Hydrocarbon Change in Recommendation
(including any changes thereto) and the identity of the Person making any such
Acquisition Proposal. Hydrocarbon shall keep Energy Partners informed on a
reasonably current basis of material developments with respect to any such
Acquisition Proposal or any matter giving rise to a Hydrocarbon Change in
Recommendation.

        (e)   Nothing contained in this Agreement shall prevent Hydrocarbon or
the Hydrocarbon Board from taking and disclosing to its stockholders a position
contemplated by Rule 14d-9 and Rule 14e-2(a) promulgated under the Exchange Act
(or any similar communication to stockholders) or from making any legally
required disclosure to stockholders. Any "stop-look-and-listen" communication by
Hydrocarbon or the Hydrocarbon Board to the stockholders of Hydrocarbon pursuant
to Rule 14d-9(f) promulgated under the Exchange Act (or any similar
communication to the stockholders of Hydrocarbon) shall not be considered a
failure to make, or a withdrawal, modification or change in any manner adverse
to Energy Partners of, all or a portion of the Hydrocarbon Recommendation.

        Section 6.7    Affiliate Arrangements.    

        (a)   Not later than the 15th day after the mailing of the Joint Proxy
Statement, Hydrocarbon shall deliver to Energy Partners a schedule of each
person that, to the best of its knowledge, is or is reasonably likely to be, as
of the date of the relevant Meeting, deemed to be an "affiliate" of Hydrocarbon
(a "Rule 145 Affiliate") as that term is used in Rule 145 under the Securities
Act.

        (b)   Hydrocarbon shall use its commercially reasonable best efforts to
cause its Rule 145 Affiliates not to sell any securities received under the
Merger in violation of the registration requirements of the Securities Act,
including Rule 145 thereunder.

        Section 6.8    Takeover Laws.    Neither party shall take any action
that would cause the transactions contemplated by this Agreement to be subject
to requirements imposed by any Takeover Laws, and each of them shall take all
necessary steps within its control to exempt (or ensure the continued exemption
of) the transactions contemplated by this Agreement from, or if necessary
challenge the validity or applicability of, any stockholder rights plan adopted
by such party or any applicable Takeover Law, as now or hereafter in effect,
including, without limitation, Takeover Laws of any state that purport to apply
to this Agreement or the transactions contemplated hereby.

31

--------------------------------------------------------------------------------

        Section 6.9    No Rights Triggered.    Each of Hydrocarbon and Energy
Partners shall take all steps necessary to ensure that the entering into of this
Agreement and the consummation of the transactions contemplated hereby and any
other action or combination of actions, or any other transactions contemplated
hereby, do not and will not result in the grant of any Rights to any person
(a) in the case of Hydrocarbon under its certificate of incorporation or bylaws
and in the case of Energy Partners under its Partnership Agreement or (b) under
any material agreement to which it or any of its Subsidiaries is a party.

        Section 6.10    Common Units Listed.    In the case of Energy Partners,
Energy Partners shall use its commercially reasonable best efforts to list,
prior to the Closing, on the NYSE, upon official notice of issuance, the Common
Units to be issued to the holders of Hydrocarbon Common Stock in the Merger.

        Section 6.11    Third Party Approvals.    

        (a)   Energy Partners and Hydrocarbon and their respective Subsidiaries,
shall cooperate and use their respective commercially reasonable best efforts to
prepare all documentation, to effect all filings, to obtain all permits,
consents, approvals and authorizations of all third parties and HSR approval
necessary to consummate the transactions contemplated by this Agreement and to
comply with the terms and conditions of such permits, consents, approvals and
authorizations and to cause the Redemption and/or Merger to be consummated as
expeditiously as practicable. Each of Energy Partners and Hydrocarbon shall have
the right to review in advance, and to the extent practicable each will consult
with the other, in each case subject to applicable laws relating to the exchange
of information, with respect to, all material written information submitted to
any third party or any Regulatory Authorities in connection with the
transactions contemplated by this Agreement. In exercising the foregoing right,
each of the parties hereto agrees to act reasonably and promptly. Each party
hereto agrees that it will consult with the other parties hereto with respect to
the obtaining of all material permits, consents, approvals and authorizations of
all third parties and Regulatory Authorities necessary or advisable to
consummate the transactions contemplated by this Agreement, and each party will
keep the other parties apprised of the status of material matters relating to
completion of the transactions contemplated hereby.

        (b)   Each party agrees, upon request, to furnish the other party with
all information concerning itself, its Subsidiaries, directors, officers and
stockholders and such other matters as may be reasonably necessary or advisable
in connection with the Registration Statement, the Joint Proxy Statement or any
filing, notice or application made by or on behalf of such other party or any of
such Subsidiaries to any Regulatory Authority in connection with the
transactions contemplated hereby.

        Section 6.12    Indemnification; Directors' and Officers' Insurance.    

        (a)   Without limiting any additional rights that any director, officer,
trustee, employee, agent, or fiduciary may have under any employment or
indemnification agreement or under the Hydrocarbon Charter, the Hydrocarbon
Bylaws or this Agreement or, if applicable, similar organizational documents or
agreements of any of Hydrocarbon's Subsidiaries, from and after the Effective
Time, Energy Partners and the Surviving Entity, jointly and severally, shall:
(i) indemnify and hold harmless each person who is at the date hereof or during
the period from the date hereof through the date of the Effective Time serving
as a director or officer of Hydrocarbon or any of its Subsidiaries or as a
fiduciary under or with respect to any employee benefit plan (within the meaning
of Section 3(3) of ERISA) (collectively, the "Indemnified Parties") to the
fullest extent authorized or permitted by applicable law, as now or hereafter in
effect, in connection with any Claim and any losses, claims, damages,
liabilities, costs, Indemnification Expenses, judgments, fines, penalties and
amounts paid in settlement (including all interest, assessments and other
charges paid or payable in connection with or in respect of any thereof)
resulting therefrom; and (ii) promptly pay on behalf of or, within ten (10) days
after any request for advancement, advance to each of the Indemnified Parties,
any Indemnification Expenses incurred in defending, serving as a witness with
respect to or otherwise

32

--------------------------------------------------------------------------------

participating with respect to any Claim in advance of the final disposition of
such Claim, including payment on behalf of or advancement to the Indemnified
Party of any Indemnification Expenses incurred by such Indemnified Party in
connection with enforcing any rights with respect to such indemnification and/or
advancement, in each case without the requirement of any bond or other
security). The indemnification and advancement obligations of Energy Partners
and the Surviving Entity pursuant to this Section 6.12(a) shall extend to acts
or omissions occurring at or before the Effective Time and any Claim relating
thereto (including with respect to any acts or omissions occurring in connection
with the approval of this Agreement and the consummation of the Redemption and
Merger and the transactions contemplated by this Agreement, including the
consideration and approval thereof and the process undertaken in connection
therewith and any Claim relating thereto), and all rights to indemnification and
advancement conferred hereunder shall continue as to a person who has ceased to
be a director or officer of Hydrocarbon or any of its Subsidiaries after the
date hereof and shall inure to the benefit of such person's heirs, executors and
personal and legal representatives. As used in this Section 6.12(a): (x) the
term "Claim" means any threatened, asserted, pending or completed action,
whether instituted by any party hereto, any Governmental Authority or any other
person, that any Indemnified Party in good faith believes might lead to the
institution of any Action, whether civil, criminal, administrative,
investigative or other, including any arbitration or other alternative dispute
resolution mechanism, arising out of or pertaining to matters that relate to
such Indemnified Party's duties or service as a director or officer of
Hydrocarbon, any of its Subsidiaries, or any employee benefit plan (within the
meaning of Section 3(3) of ERISA) maintained by any of the foregoing at or prior
to the Effective Time; and (y) the term "Indemnification Expenses" means
reasonable attorneys' fees and all other reasonable costs, expenses and
obligations (including experts' fees, travel expenses, court costs, retainers,
transcript fees, duplicating, printing and binding costs, as well as
telecommunications, postage and courier charges) paid or incurred in connection
with investigating, defending, being a witness in or participating in (including
on appeal), or preparing to investigate, defend, be a witness in or participate
in, any Claim for which indemnification is authorized pursuant to this
Section 6.12(a), including any Action relating to a claim for indemnification or
advancement brought by an Indemnified Party. Neither Energy Partners nor the
Surviving Entity shall settle, compromise or consent to the entry of any
judgment in any actual or threatened Action in respect of which indemnification
has been or could be sought by such Indemnified Party hereunder unless such
settlement, compromise or judgment includes an unconditional release of such
Indemnified Party from all liability arising out of such Action without
admission or finding of wrongdoing, or such Indemnified Party otherwise consents
thereto.

        (b)   Without limiting the foregoing, Energy Partners and MergerCo agree
that all rights to indemnification, advancement of expenses and exculpation from
liabilities for acts or omissions occurring at or prior to the Effective Time
now existing in favor of the current or former directors or officers of
Hydrocarbon or any of its Subsidiaries as provided in the Hydrocarbon Charter
and Hydrocarbon Bylaws (or, as applicable, the charter, bylaws, partnership
agreement, limited liability company agreement, or other organizational
documents of any of Hydrocarbon's Subsidiaries) and indemnification agreements
of Hydrocarbon or any of its Subsidiaries shall be assumed by the Surviving
Entity in the Merger, without further action, at the Effective Time and shall
survive the Merger and shall continue in full force and effect in accordance
with their terms.

        (c)   For a period of six (6) years from the Effective Time, the
certificate of incorporation and bylaws of the Surviving Entity shall contain
provisions no less favorable with respect to indemnification, advancement of
expenses and limitations on liability of directors and officers than are set
forth in the Hydrocarbon Charter and Hydrocarbon Bylaws, which provisions shall
not be amended, repealed or otherwise modified for a period of six (6) years
from the Effective Time in any manner that would affect adversely the rights
thereunder of individuals who, at or prior to the Effective Time, were
Indemnified Parties, unless such modification shall be required by Law and then
only to the minimum extent required by Law.

33

--------------------------------------------------------------------------------

        (d)   Energy Partners shall, or shall cause the Surviving Entity to,
maintain for a period of at least six (6) years following the Effective Time,
the current policies of directors' and officers' liability insurance maintained
by Hydrocarbon and its Subsidiaries (provided, that the Surviving Entity may
substitute therefor policies of at least the same coverage and amounts
containing terms and conditions which are not less advantageous to such
directors and officers of Hydrocarbon than the terms and conditions of such
existing policy from carriers with the same or better rating as the carrier
under the existing policy provided that such substitution shall not result in
gaps or lapses of coverage with respect to matters occurring before the
Effective Time) with respect to claims arising from facts or events that
occurred on or before the Effective Time, including in respect of the Redemption
and Merger and the transactions contemplated by this Agreement; provided, that
Energy Partners shall not be required to pay annual premiums in excess of 250%
of the last annual premium paid by Hydrocarbon prior to the date hereof but in
such case shall purchase as much coverage as reasonably practicable for such
amount.

        (e)   The provisions of Section 6.12(d) shall be deemed to have been
satisfied if prepaid "tail" policies have been obtained by the Surviving Entity
for purposes of this Section 6.12 from carriers with the same or better rating
as the carrier of such insurances as of the date of this Agreement, which
policies provide such directors and officers with the coverage described in
Section 6.12(d) for an aggregate period of not less than six (6) years with
respect to claims arising from facts or events that occurred on or before the
Effective Time, including, in respect of the Redemption and Merger and the
transactions contemplated by this Agreement.

        (f)    If the Surviving Entity or any of its respective successors or
assigns (i) consolidates with or merges with or into any other person and shall
not be the continuing or surviving corporation, partnership or other entity of
such consolidation or merger or (ii) transfers or conveys all or substantially
all of its properties and assets to any person, then, and in each such case,
proper provision shall be made so that the successors and assigns of the
Surviving Entity assume the obligations set forth in this Section 6.12.

        (g)   Energy Partners shall cause the Surviving Entity to perform all of
the obligations of the Surviving Entity under this Section 6.12.

        (h)   This Section 6.12 shall survive the consummation of the Redemption
and Merger and is intended to be for the benefit of, and shall be enforceable
by, the Indemnified Parties and their respective heirs and personal
representatives, and shall be binding on the Surviving Entity and its successors
and assigns.

        Section 6.13    Comfort Letters.    

        (a)   Hydrocarbon shall use all commercially reasonable best efforts to
cause to be delivered to Energy Partners a "comfort" letter of Deloitte & Touche
LLP, Hydrocarbon's independent public accountants, dated and delivered the date
on which the Registration Statement shall become effective, in form and
substance reasonably satisfactory to the Conflicts Committee and customary in
scope and substance for letters delivered by independent public accountants in
connection with registration statements similar to the Registration Statement.

        (b)   Energy Partners shall use all commercially reasonable best efforts
to cause to be delivered to Hydrocarbon a "comfort" letter of Deloitte & Touche
LLP, Energy Partners' independent public accountants, dated and delivered the
date on which the Registration Statement shall become effective, in form and
substance reasonably satisfactory to the Deal Committee and customary in scope
and substance for letters delivered by independent public accountants in
connection with registration statements similar to the Registration Statement.

34

--------------------------------------------------------------------------------

        Section 6.14    Benefit Plans.    The parties agree to take such actions
with respect to compensation and employee benefit plans, programs, arrangements
and other perquisites as are set forth on Schedule 4.5 of Hydrocarbon's
Disclosure Schedule.

        Section 6.15    Notification of Certain Matters.    Each of Hydrocarbon
and Energy Partners shall give prompt notice to the other of (a) any fact, event
or circumstance known to it that (i) is reasonably likely, individually or taken
together with all other facts, events and circumstances known to it, to result
in any Material Adverse Effect with respect to it or (ii) would cause or
constitute a material breach of any of its representations, warranties,
covenants or agreements contained herein, and (b) any change in its condition
(financial or otherwise) or business or any litigation or governmental
complaints, investigations or hearings, in each case to the extent such change,
litigation, complaints, investigations, or hearings results in, or would
reasonably be expected to result in, a Material Adverse Effect.

        Section 6.16    Rule 16b-3.    Prior to the Effective Time, Hydrocarbon
shall take such steps as may be reasonably requested by any party hereto to
cause dispositions of Hydrocarbon equity securities (including derivative
securities) pursuant to the transactions contemplated by this Agreement by each
individual who is a director or officer of Hydrocarbon to be exempt under
Rule 16b-3 promulgated under the Exchange Act in accordance with that certain
No-Action Letter dated January 12, 1999 issued by the SEC regarding such
matters.

        Section 6.17    Amended and Restated Partnership Agreement.    Subject
to receipt of the Energy Partners Unitholder Approval, Energy Partners shall
execute and make effective the Amended and Restated Partnership Agreement.

        Section 6.18    Board Membership.    Prior to the mailing of the Joint
Proxy Statement, Hydrocarbon shall designate in its sole discretion three
(3) members from among the current members of the Hydrocarbon Board, two (2) of
whom must be independent (the "Hydrocarbon Director Designees") to serve as
members of the Board of Directors of General Partner following the Effective
Time. Subject to the foregoing, the parties shall take such action as is
necessary to cause the General Partner to cause the Hydrocarbon Director
Designees to be appointed to the Board of Directors of General Partner effective
as of the Effective Time, to serve until the earlier of such individual's
resignation or removal or until his successor is duly elected and qualified.

ARTICLE VII

CONDITIONS TO CONSUMMATION OF THE REDEMPTION AND MERGER

        The obligations of each of the parties to consummate the Redemption and
Merger are conditioned upon the satisfaction at or prior to the Closing of each
of the following:

        Section 7.1    Stockholder Vote.    The Merger, the Unit Issuance, the
Amended and Restated Partnership Agreement and the other transactions
contemplated hereby shall have been approved and adopted by the affirmative vote
of a Unit Majority at the Energy Partners Meeting ("Energy Partners Unitholder
Approval"), and the Redemption Charter Amendment, the Merger and this Agreement
and the other transactions contemplated hereby shall have been approved and
adopted by the affirmative vote of the holders of a majority of the shares of
Hydrocarbon Common Stock outstanding and entitled to vote thereon at the
Hydrocarbon Meeting ("Hydrocarbon Stockholder Approval").

        Section 7.2    Governmental Approvals.    Any waiting period (including
any extended waiting period arising as a result of a request for additional
information by the Federal Trade Commission or the U.S. Department of Justice)
under the HSR shall have expired or been terminated. All other filings required
to be made prior to the Effective Time with, and all other consents, approvals,
permits and authorizations required to be obtained prior to the Effective Time
from, any Regulatory Authority in connection with the execution and delivery of
this Agreement and the consummation of the transactions contemplated hereby by
the parties hereto or their Affiliates shall have been made or

35

--------------------------------------------------------------------------------

obtained, except where the failure to obtain such consents, approvals, permits
and authorizations would not be reasonably likely to result in a Material
Adverse Effect on Energy Partners or Hydrocarbon.

        Section 7.3    No Injunction.    No order, decree or injunction of any
court or agency of competent jurisdiction shall be in effect, and no law,
statute or regulation shall have been enacted or adopted, that enjoins,
prohibits or makes illegal consummation of any of the transactions contemplated
hereby, and no action, proceeding or investigation by any Regulatory Authority
with respect to the Redemption, the Merger or the other transactions
contemplated hereby shall be pending that seeks to restrain, enjoin, prohibit or
delay consummation of the Redemption, the Merger or such other transaction or to
impose any material restrictions or requirements thereon or on Energy Partners
or Hydrocarbon with respect thereto; provided, however, that prior to invoking
this condition, each party shall have complied fully with its obligations under
Section 6.1.

        Section 7.4    Representations, Warranties and Covenants of Energy
Partners.    In the case of Hydrocarbon's obligation to consummate the
Redemption and the Merger:

        (a)   each of the representations and warranties contained herein of
Energy Partners shall be true and correct as of the date of this Agreement and
upon the Closing Date with the same effect as though all such representations
and warranties had been made on the Closing Date, except for any such
representations and warranties made as of a specified date, which shall be true
and correct as of such date, in any case subject to the standard set forth in
Section 5.2;

        (b)   each and all of the agreements and covenants of Energy Partners to
be performed and complied with pursuant to this Agreement on or prior to the
Closing Date shall have been duly performed and complied with in all material
respects; and

        (c)   Hydrocarbon shall have received a certificate signed by the Chief
Financial Officer of the General Partner, dated the Closing Date, to the effect
set forth in Section 7.4(a) and Section 7.4(b).

        Section 7.5    Representations, Warranties and Covenants of
Hydrocarbon.    In the case of Energy Partners' obligation to consummate the
Merger:

        (a)   each of the representations and warranties contained herein of
Hydrocarbon shall be true and correct as of the date of this Agreement and upon
the Closing Date with the same effect as though all such representations and
warranties had been made on the Closing Date, except for any such
representations and warranties made as of a specified date, which shall be true
and correct as of such date, in any case subject to the standard set forth in
Section 5.2;

        (b)   each and all of the agreements and covenants of Hydrocarbon to be
performed and complied with pursuant to this Agreement on or prior to the
Closing Date shall have been duly performed and complied with in all material
respects; and

        (c)   Energy Partners shall have received a certificate signed by the
Chief Financial Officer of Hydrocarbon, dated the Closing Date, to the effect
set forth in Section 7.5(a) and Section 7.5(b).

        Section 7.6    Effective Registration Statement.    The Registration
Statement shall have become effective under the Securities Act and no stop order
suspending the effectiveness of the Registration Statement shall have been
issued and no proceedings for that purpose shall have been initiated or
threatened by the SEC or any other Regulatory Authority.

        Section 7.7    Opinion of Vinson & Elkins L.L.P. or Other Counsel.    In
the case of Energy Partners' obligation to consummate the Merger, Energy
Partners shall have received an opinion from Vinson & Elkins L.L.P., counsel to
Energy Partners, or other counsel that is reasonably acceptable to Energy
Partners, to the effect that:

        (a)   the Merger and the transactions contemplated by this Agreement
will not result in the loss of limited liability of any limited partner of
Energy Partners;

36

--------------------------------------------------------------------------------

        (b)   90% of the current gross income of Energy Partners constitutes
qualifying income within the meaning of Section 7704(d) of the Code;

        (c)   the Merger and the transactions contemplated by this Agreement
will not cause Energy Partners to be treated as an association taxable as a
corporation or otherwise to be taxed as an entity for federal income tax
purposes;

        (d)   to the extent that it describes provisions of United States
federal tax law, the discussion in the Registration Statement under the caption
"Material U.S. Federal Income Tax Consequences," as it relates to the holders of
Common Units (other than Hydrocarbon), is correct in all material respects; and

        (e)   no gain or loss should be recognized by holders of Common Units as
a result of the Merger (other than gain resulting from any decrease in
partnership liabilities pursuant to Section 752 of the Code).

        In rendering such opinions, Vinson & Elkins L.L.P. or other counsel may
require and rely upon representations and covenants including those contained in
certificates of officers of the General Partner and others and opinions of
Delaware counsel, reasonably satisfactory in form and substance to such counsel.

        Section 7.8    Opinion of Hogan & Hartson L.L.P. or Other Counsel.    In
the case of Hydrocarbon's obligation to consummate the Redemption and the
Merger, Hydrocarbon shall have received an opinion from Hogan & Hartson L.L.P.,
counsel to Hydrocarbon, or other counsel that is reasonably acceptable to
Hydrocarbon, to the effect that:

        (a)   to the extent that it describes provisions of United States
federal tax law, the discussion in the Registration Statement under the caption
"Material U.S. Federal Income Tax Consequences," as it relates to the holders of
Hydrocarbon Common Stock, is correct in all material respects; and

        (b)   no gain or loss should be recognized by the holders of Hydrocarbon
Common Stock to the extent Common Units are received in exchange therefor as a
result of the Merger.

        In rendering such opinion, Hogan & Hartson L.L.P. or other counsel may
require and rely upon representations and covenants including those contained in
certificates of officers of Hydrocarbon and others and opinions of Delaware
counsel reasonably satisfactory in form and substance to such counsel.

        Section 7.9    NYSE Listing.    The Common Units issuable pursuant to
this Agreement shall have been approved for listing on the NYSE, subject to
official notice of issuance.

        Section 7.10    Amended and Restated Partnership Agreement.    In the
case of Hydrocarbon's obligation to consummate the Redemption and the Merger,
Energy Partners shall have executed and made effective the Amended and Restated
Partnership Agreement.

        Section 7.11    Dissenting Holders.    In the case of Energy Partners'
obligation to consummate the Merger, the shares of Hydrocarbon Common Stock held
by Dissenting Holders shall not exceed 5% of the outstanding shares of
Hydrocarbon Common Stock immediately prior to the Redemption.

        Section 7.12    Resignation of the Hydrocarbon Board.    In the case of
Energy Partners' obligation to consummate the Merger, Hydrocarbon shall have
received resignations for all of the directors on the Hydrocarbon Board.

        Section 7.13    Restructuring Transactions.    The Restructuring
Transactions shall have been consummated pursuant to the Exchange Agreement.

        Section 7.14    Valuation Appraisal.    In the case of Hydrocarbon's
obligation to consummate the Redemption and the Merger, Energy Partners shall
have received an appraisal from Duff & Phelps Acquisitions, LLC, which appraisal
comes to the conclusion that the value of (i) the Common Units

37

--------------------------------------------------------------------------------

owned by Hydrocarbon and (ii) the IDRs and the economic interest in the 2%
general partner interest in Energy Partners owned by the General Partner,
collectively, can reasonably be found to be equal to the value of the Class A
Units for which such common units, IDRs and economic interest in the general
partner interest are being exchanged in consummation of the Restructuring
Transactions as provided for in the Exchange Agreement.

        Section 7.15    Changes in Tax Law.    

        (a)   Hydrocarbon shall not be obligated to consummate the Redemption;
and neither Hydrocarbon nor Energy Partners shall be obligated to consummate the
Merger if either of the following shall have occurred:

        (i)    the issuance of Proposed Treasury Regulations Section 1.337(d)-3
in final form, with an effective date that would cause the final regulations to
be applicable to the Merger, unless Hydrocarbon or Energy Partners, as the case
may be, has received an opinion, in a form reasonably acceptable to it, from a
law or accounting firm, that such regulations should not cause Hydrocarbon to
recognize income or gain as a result of either the Merger or Restructuring
Transactions, or

        (ii)   a Change in U.S. Federal Income Tax Law, other than as
contemplated under clause (i), unless Hydrocarbon or Energy Partners, as the
case may be, has received an opinion, in a form reasonably acceptable to it,
from a law or accounting firm, that such change should not cause Hydrocarbon to
recognize income or gain as a result of either the Merger or Restructuring
Transactions.

        (b)   "Change in U.S. Federal Income Tax Law" means any change in the
Code, Treasury Regulations, administrative pronouncements of the Internal
Revenue Service, or judicial interpretations of the foregoing, if the Deal
Committee or the Conflicts Committee determines, in its reasonable judgment,
that it is more likely than not that such change could materially and adversely
affect the U.S. federal income tax consequences to Hydrocarbon from the Merger
or Restructuring Transactions.

        Section 7.16    Redemption.    In the case of Hydrocarbon's and Energy
Partners' obligation to consummate the Merger, the Redemption has been
consummated pursuant to the Redemption Charter Amendment, subject to the payment
of the redemption price of the Per Share Cash Consideration as provided in
Section 3.5.

ARTICLE VIII

TERMINATION

        Section 8.1    Termination.    Notwithstanding anything herein to the
contrary, this Agreement may be terminated and the Redemption and the Merger may
be abandoned at any time prior to the Effective Time whether before or after the
Hydrocarbon Stockholder Approval or Energy Partners Unitholder approval:

        (a)   By the mutual consent of Energy Partners and Hydrocarbon in a
written instrument.

        (b)   By either Hydrocarbon or Energy Partners upon written notice to
the other, if:

        (i)    the Redemption and the Merger have not been consummated on or
before February 27, 2008 (the "Termination Date"); provided that the right to
terminate this Agreement pursuant to this Section 8.1(b) (i) shall not be
available to a party whose failure to fulfill any material obligation under this
Agreement or other material breach of this Agreement has been the primary cause
of, or resulted in, the failure of the Redemption or Merger to have been
consummated on or before such date;

38

--------------------------------------------------------------------------------

        (ii)   any Regulatory Authority has issued a statute, rule, order,
decree or regulation or taken any other action (which statute, rule, order,
decree, regulation or other action the parties hereto shall have used their
commercially reasonable best efforts to lift), in each case permanently
restraining, enjoining or otherwise prohibiting the consummation of the
Redemption or the Merger or making the Redemption or the Merger illegal and such
statute, rule, order, decree, regulation or other action shall have become final
and nonappealable (provided that the terminating party is not then in breach of
Section 6.1);

        (iii)  Hydrocarbon fails to obtain Hydrocarbon Stockholder Approval at
the Hydrocarbon Meeting; provided that Hydrocarbon shall not be entitled to
terminate this Agreement pursuant to this Section 8.1(b)(iii) if it has breached
any of its obligations under Section 6.6;

        (iv)  there has been a material breach of or any inaccuracy in any of
the representations or warranties set forth in this Agreement on the part of any
of the other parties (treating Energy Partners and MergerCo as one party for the
purposes of this Section 8.1), which breach is not cured within 30 days
following receipt by the breaching party of written notice of such breach from
the terminating party, or which breach, by its nature, cannot be cured prior to
the Termination Date (provided in any such case that the terminating party is
not then in material breach of any representation, warranty, covenant or other
agreement contained herein); provided, however, that no party shall have the
right to terminate this Agreement pursuant to this Section 8.1(b)(iv) unless the
breach of representation or warranty, together with all other such breaches,
would entitle the party receiving such representation not to consummate the
transactions contemplated by this Agreement under Section 7.4 (in the case of a
breach of representation or warranty by Energy Partners or MergerCo) or
Section 7.5 (in the case of a breach of representation or warranty by
Hydrocarbon);

        (v)   if there has been a material breach of any of the covenants or
agreements set forth in this Agreement on the part of any of the other parties,
which breach has not been cured within 30 days following receipt by the
breaching party of written notice of such breach from the terminating party, or
which breach, by its nature, cannot be cured prior to the Termination Date
(provided in any such case that the terminating party is not then in material
breach of any representation, warranty, covenant or other agreement contained
herein); provided, however, that no party shall have the right to terminate this
Agreement pursuant to this Section 8.1(b)(v) unless the breach of covenants or
agreements, together with all other such breaches, would entitle the party
receiving the benefit of such covenants or agreements not to consummate the
transactions contemplated by this Agreement under Section 7.4. (in the case of a
breach of covenants or agreements by Energy Partners or MergerCo) or
Section 7.5. (in the case of a breach of covenants or agreements by
Hydrocarbon); or

        (vi)  Energy Partners fails to obtain the Energy Partners Unitholder
Approval at the Energy Partners Meeting.

        (c)   By Energy Partners, upon written notice to Hydrocarbon, in the
event that: (i) Hydrocarbon shall have materially breached Section 6.6; or
(ii) a Hydrocarbon Change in Recommendation has occurred.

        (d)   By Hydrocarbon (with the prior approval of the Deal Committee),
upon written notice to Energy Partners, in the event that (i) if, at any time
after the date of this Agreement and prior to obtaining the Hydrocarbon
Stockholder Approval, Hydrocarbon receives an Acquisition Proposal and the
Hydrocarbon Board (acting through the Deal Committee if such committee still
exists) shall have concluded in good faith that such Acquisition Proposal
constitutes a Superior Proposal, Hydrocarbon has complied with Section 6.6(c) of
this Agreement, and the Hydrocarbon Board concurrently approves, and Hydrocarbon
concurrently enters into, a definitive agreement with respect to such Superior

39

--------------------------------------------------------------------------------

Proposal and has paid the Hydrocarbon Termination Fee pursuant to
Section 9.1(b), or (ii) an Energy Partners Change in Recommendation has
occurred.

        Section 8.2    Effect of Termination.    In the event of the termination
of this Agreement as provided in Section 8.1, written notice thereof shall
forthwith be given by the terminating party to the other parties specifying the
provision of this Agreement pursuant to which such termination is made, and
except as provided in this Section 8.2, this Agreement (other than Article IX)
shall forthwith become null and void after the expiration of any applicable
period following such notice. In the event of such termination, there shall be
no liability on the part of Energy Partners, MergerCo or Hydrocarbon, except as
set forth in Section 9.1 of this Agreement and except with respect to the
requirement to comply with the Confidentiality Agreement; provided that nothing
herein shall relieve any party from any liability or obligation with respect to
any fraud or intentional breach of this Agreement.

ARTICLE IX

MISCELLANEOUS

        Section 9.1    Fees and Expenses.    

        (a)   Whether or not the Redemption and the Merger are consummated, all
costs and expenses incurred in connection with this Agreement and the
transactions contemplated hereby shall be paid by the party incurring such costs
or expenses, except as provided in Section 9.1(b), 9.1(c), 9.1(d) and 9.1(f).

        (b)   If this Agreement is terminated by Energy Partners pursuant to
Section 8.1(c) or by Hydrocarbon pursuant to Section 8.1(d)(i), then Hydrocarbon
shall pay to the Escrow Agent for the benefit of Energy Partners the Hydrocarbon
Termination Fee. If this Agreement is terminated by Hydrocarbon pursuant to
Section 8.1(d)(ii), then Energy Partners shall pay to Hydrocarbon in immediately
available funds the Energy Partners Termination Fee. If this Agreement is
terminated by Energy Partners pursuant to Section 8.1(b)(iv) or
Section 8.1(b)(v) or by Hydrocarbon or Energy Partners pursuant to
Section 8.1(b)(iii), then Hydrocarbon shall pay to the Escrow Agent for the
benefit of Energy Partners the Expenses of Energy Partners; provided, however,
that Hydrocarbon shall not be obligated to pay the Expenses to Energy Partners
in connection with the termination of this Agreement pursuant to
Section 8.1(b)(iii) if Mr. Fox failed to comply with the terms of the Fox
Support Agreement.

        (c)   In the event that (i) an Acquisition Proposal with respect to
Hydrocarbon has been proposed by any Person (meaning, for the purpose of this
Section 9.1(c), a Person other than Energy Partners and MergerCo) or any Person
has publicly announced its intention (whether or not conditional) to make such
an Acquisition Proposal or such an Acquisition Proposal or such intention has
otherwise become publicly known to Hydrocarbon's stockholders generally and in
any event such proposal or intention is not subsequently withdrawn prior to the
termination of this Agreement, (ii) thereafter this Agreement is terminated by
either Hydrocarbon or Energy Partners pursuant to Section 8.1(b)(i) or
Section 8.1(b)(iii) or by Energy Partners pursuant to Section 8.1(b)(iv) or
Section 8.1(b)(v), and (iii) within 12 months after the termination of this
Agreement, Hydrocarbon or any of its Subsidiaries enters into any definitive
agreement providing for an Acquisition Proposal, or an Acquisition Proposal with
respect to Hydrocarbon or any of its Subsidiaries is consummated, then
Hydrocarbon shall pay to the Escrow Agent for the benefit of Energy Partners, if
and when consummation of such Acquisition Proposal occurs, the Hydrocarbon
Termination Fee less all Expenses of Energy Partners previously paid to Energy
Partners; provided that for purposes of this Section 9.1(c), "50%" shall be
substituted for "20%" in the definition of Acquisition Proposal.

40

--------------------------------------------------------------------------------

        (d)   If this Agreement is (i) terminated by Hydrocarbon or Energy
Partners pursuant to Section 8.1(b)(vi), or (ii) terminated by Hydrocarbon
pursuant to Section 8.1(b)(iv) or Section 8.1(b)(v), then Energy Partners shall
pay to Hydrocarbon the Expenses of Hydrocarbon.

        (e)   Except as otherwise provided herein, any payment of the
Hydrocarbon Termination Fee, the Energy Partners Termination Fee or Expenses
pursuant to this Section 9.1 shall be made by wire transfer of immediately
available funds to an account of the Escrow Agent designated by Energy Partners
or an account designated by Hydrocarbon, as applicable, within one Business Day
after such payment becomes payable; provided, however, that any payment of the
Hydrocarbon Termination Fee pursuant to Section 9.1(b) by Hydrocarbon as a
result of termination under Section 8.1(d)(i) shall be made prior to or
concurrently with termination of this Agreement; provided, further, that any
payment of the Hydrocarbon Termination Fee pursuant to Section 9.1(c) shall be
made contemporaneously with the consummation of the Acquisition Proposal as
provided in clause (iii) of Section 9.1(c). The parties acknowledge that the
agreements contained in this Section 9.1 are an integral part of the
transactions contemplated by this Agreement, and that, without these agreements,
none of the parties would enter into this Agreement.

        (f)    (i) If the Redemption and the Merger are consummated, the
Surviving Entity shall pay, or cause to be paid, any and all property or
transfer taxes imposed on either party in connection with the Merger,
(ii) expenses incurred in connection with filing, printing and mailing the Joint
Proxy Statement and the Registration Statement shall be paid by Energy Partners
and (iii) filing fees payable pursuant to the HSR Act, regulatory laws and other
filing fees incurred in connection with this Agreement shall be paid by the
party incurring the fees. As used in this agreement, "Expenses" includes good
faith estimate of all out-of-pocket expenses (including all fees and expenses of
counsel, accountants, investment bankers, experts and consultants to a party
hereto and its affiliates) incurred by a party or on its behalf in connection
with or related to the authorization, preparation, negotiation, execution and
performance of this Agreement and the transactions contemplated hereby,
including the preparation, printing, filing and mailing of the Joint Proxy
Statement and the Registration Statement and the solicitation of
stockholder/unitholder approvals and all other matters related to the
transactions contemplated hereby; provided that the amount of Expenses payable
by one party to another under this Section 9.1 shall not exceed $6.0 million.

        (g)   Any amounts paid to the Escrow Agent pursuant to this Article IX,
together with interest thereon (the "Escrow Fund"), shall be released by the
Escrow Agent to Energy Partners as follows:

        (i)    Prior to the end of the calendar year in which the payment was
made to the Escrow Agent, Energy Partners shall submit to the Escrow Agent a
certificate demanding a portion of the Escrow Fund equal to no greater than 70%
of the maximum remaining amount which, in the good faith view of the General
Partner, may still be taken into the gross revenues of Energy Partners without
exceeding the permissible qualifying income (as defined in Section 7704 of the
Code) limits for a publicly traded partnership, after taking into consideration
all other sources of non-qualifying income (such maximum remaining amount, the
"Non-Qualifying Income Cushion"), and the Escrow Agent shall within one Business
Day thereafter, pay Energy Partners the amount demanded, by wire transfer of
immediately available funds to an account designated by Energy Partners;

        (ii)   During the calendar year following the date that the payment was
made to the Escrow Agent but prior to the passage of 30 calendar days following
the filing of the IRS Form 1065 for the prior year, Energy Partners shall submit
to the Escrow Agent a certificate identifying the actual Non-Qualifying Income
Cushion from the prior year. If the payment contemplated by clause (i) above was
(A) less than 80% of the actual Non-Qualifying Income Cushion, then Energy
Partners shall submit to the Escrow Agent a certificate demanding a portion of
the Escrow Fund equal to an amount which, when combined with the payment
contemplated by clause (i) will equal 90% of

41

--------------------------------------------------------------------------------

the actual Non-Qualifying Income Cushion, and the Escrow Agent shall within one
Business Day thereafter, pay Energy Partners the amount demanded, (B) greater
than or equal to 80%, but less than or equal to 90% of the actual Non-Qualifying
Income Cushion, then Energy Partners shall notify the Escrow Agent that it will
not demand any additional payments from the Escrow Account, and (C) greater than
90% of the actual Non-Qualifying Income Cushion, then Energy Partners shall
deliver a certificate to such effect to the Escrow Agent and return to the
Escrow Fund an amount equal to the excess of the payment contemplated by
clause (i) over 80% of the Non-Qualifying Income Cushion. Any payment under this
clause (ii) shall be made by the Escrow Agent, or Energy Partners, as the case
may be, by wire transfer of immediately available funds to an account designated
by Energy Partners or the Escrow Agent, as the case may be; and

        (iii)  Within one Business Day following the earlier of (A) completion
of the procedures as contemplated by Section 9.1(g)(ii) above and (B) the
passage of 30 days following the filing of the IRS Form 1065 for the prior year,
the Escrow Agent shall pay Hydrocarbon the remainder, if any, of the Escrow
Fund, by wire transfer of immediately available funds to an account designated
by Hydrocarbon.

Hydrocarbon acknowledges and agrees that (x) the amount of a payment, if any,
pursuant to Section 9.1(g)(ii) above is uncertain, and that depending on the
amount of the demands made by Energy Partners pursuant to
Section 9.1(g)(ii) above, the Escrow Fund may be insufficient to permit payments
to Hydrocarbon pursuant to Section 9.1(g)(ii) above, and (y) it shall have no
rights to any amounts in the Escrow Fund (other than as contemplated by this
subsection (h)) or to audit or inquire into the amounts demanded by or paid to
Energy Partners.

        (h)   Hydrocarbon agrees that, notwithstanding any right that it or the
General Partner may otherwise have, including pursuant to the Partnership
Agreement, the Amended and Restated Partnership Agreement, or otherwise, it
hereby waives and renounces for itself and its affiliates, and shall cause the
General Partner to waive and renounce, any distribution by Energy Partners to
its partners of any amount paid to Energy Partners by the Escrow Agent, together
with an income allocation associated with such distribution, it being understood
that following payment to Energy Partners from the Escrow Agent, Energy Partners
will make a distribution to the holders of common units of Energy Partners who
are unaffiliated with Hydrocarbon.

        (i)    This Section 9.1 shall survive any termination of this Agreement.

        Section 9.2    Waiver; Amendment.    Subject to compliance with
applicable law, prior to the Closing, any provision of this Agreement may be
(a) waived in writing by the party benefited by the provision and approved by
the Conflicts Committee in the case of Energy Partners and by the Deal Committee
in the case of Hydrocarbon and executed in the same manner as this Agreement, or
(b) amended or modified at any time, whether before or after the Hydrocarbon
Stockholder Approval, by an agreement in writing between the parties hereto
approved by the Conflicts Committee in the case of Energy Partners and by the
Deal Committee in the case of Hydrocarbon and executed in the same manner as
this Agreement; provided that after the Hydrocarbon Stockholder Approval, no
amendment shall be made that requires further Hydrocarbon Stockholder Approval
without such further approval.

        Section 9.3    Counterparts.    This Agreement may be executed in one or
more counterparts, each of which shall be deemed to constitute an original.

        Section 9.4    Governing Law.    This Agreement shall be governed by,
and interpreted in accordance with, the laws of the State of Delaware, without
regard to the conflict of law principles thereof (except to the extent that
mandatory provisions of federal or Delaware law govern).

        Section 9.5    Confidentiality.    Each of the parties hereto and their
respective agents, attorneys and accountants will maintain the confidentiality
of all information provided in connection herewith to the extent required by,
and subject to the limitations of, the Confidentiality Agreement.

42

--------------------------------------------------------------------------------

        Section 9.6    Notices.    All notices, requests and other
communications hereunder to a party shall be in writing and shall be deemed
given if personally delivered, telecopied (with confirmation) or mailed by
registered or certified mail (return receipt requested) to such party at its
address set forth below or such other address as such party may specify by
notice to the parties hereto.

        If to Energy Partners, to:

MarkWest Energy GP, L.L.C.
Attn: General Counsel
1515 Arapahoe Street
Tower 2, Suite 700
Denver, Colorado 80202
Fax: (303) 290-8769

        With copies to:

Chairman of the Conflicts Committee
William P. Nicoletti
c/o Nicoletti & Company Inc.
620 Van Beuren Road
Morristown, NJ 07960
Fax: (973) 440-1520

Vinson & Elkins L.L.P.
Attn: Michael J. Swidler
666 Fifth Avenue, 26th Floor
New York, NY 10103
Fax: (212)237-0100

Andrews Kurth LLP
Attn: Bill Cooper
1350 I Street, N.W., Suite 1100
Washington, D.C. 20005
Fax: (202) 662-2739

        If to Hydrocarbon, to:

MarkWest Hydrocarbon, Inc.
Attn: General Counsel
1515 Arapahoe Street
Tower 2, Suite 700
Denver, Colorado 80202
Fax: (303) 290-8769

        With copies to:

Chairman of the Deal Committee
Michael L. Beatty
Beatty & Wozniak, P.C.
Columbine Place, Suite 1100
216 Sixteenth Street
Denver, Colorado 80202-5115
Fax: (303) 407-4490

43

--------------------------------------------------------------------------------

Hogan & Hartson L.L.P.
Attn: George Hagerty
One Tabor Center, Suite 1500
1200 Seventeenth Street
Denver, Colorado 80202
Fax: (303) 899-7333

Akin, Gump, Strauss, Hauer & Feld LLP
Attn: Michael E. Dillard, P.C. and J. Vincent Kendrick
1111 Louisiana Street, 44th Floor
Houston, Texas 77002
Fax: (713) 236 -0822

        Section 9.7    Entire Understanding; No Third Party
Beneficiaries.    Except for the Confidentiality Agreement, the Class B
Membership Interest Contribution Agreement and the Exchange Agreement, all of
which shall remain in effect, this Agreement represents the entire understanding
of the parties hereto with reference to the transactions contemplated hereby and
supersedes any and all other oral or written agreements heretofore made. Except
as contemplated by Section 6.12, nothing in this Agreement, expressed or
implied, is intended to confer upon any person, other than the parties hereto or
their respective successors, any rights, remedies, obligations or liabilities
under or by reason of this Agreement.

        Section 9.8    Severability.    Any provision of this Agreement which is
invalid, illegal or unenforceable in any jurisdiction shall, as to that
jurisdiction, be ineffective to the extent of such invalidity, illegality or
unenforceability, without affecting in any way the remaining provisions hereof
in such jurisdiction or rendering that or any other provision of this Agreement
invalid, illegal or unenforceable in any other jurisdiction.

        Section 9.9    Headings.    The headings contained in this Agreement are
for reference purposes only and are not part of this Agreement.

        Section 9.10    Jurisdiction.    The parties hereto agree that any suit,
action or proceeding seeking to enforce any provision of, or based on any matter
arising out of or in connection with, this Agreement or the transactions
contemplated hereby shall be brought in any federal court located in the State
of Delaware or the Delaware Court of Chancery, and each of the parties hereby
irrevocably consents to the jurisdiction of such courts (and of the appropriate
appellate courts therefrom) in any such suit, action or proceeding and
irrevocably waives, to the fullest extent permitted by law, any objection that
it may now or hereafter have to the laying of the venue of any such suit, action
or proceeding in any such court or that any such suit, action or proceeding
brought in any such court has been brought in an inconvenient forum. Process in
any such suit, action or proceeding may be served on any party anywhere in the
world, whether within or without the jurisdiction of any such court. Without
limiting the foregoing, each party agrees that service of process on such party
as provided in Section 9.6 shall be deemed effective service of process on such
party.

        Section 9.11    Waiver of Jury Trial.    EACH OF THE PARTIES HERETO
HEREBY IRREVOCABLY WAIVES ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL
PROCEEDING ARISING OUT OF OR RELATED TO THIS AGREEMENT OR THE TRANSACTIONS
CONTEMPLATED HEREBY.

        Section 9.12    Specific Performance.    The parties agree that
irreparable damage would occur if any provision of this Agreement were not
performed in accordance with the terms hereof and, accordingly, that the parties
shall be entitled to an injunction or injunctions to prevent breaches of this
Agreement or to enforce specifically the performance of the terms and provisions
hereof in any federal court

44

--------------------------------------------------------------------------------

located in the State of Delaware or in the Delaware Court of Chancery, in
addition to any other remedy to which they are entitled at law or in equity.

        Section 9.13    Survival.    All representations, warranties, agreements
and covenants contained in this Agreement shall not survive the Closing or the
termination of this Agreement if this Agreement is terminated prior to the
Closing; provided, however, that if the Closing occurs, the agreements of the
parties in Sections 3.5, 3.7, 6.12 and Article IX shall survive the Closing, and
if this Agreement is terminated prior to the Closing, the agreements of the
parties in Section 6.5(b), 8.2, and Article IX shall survive such termination.

        Section 9.14    No Act or Failure to Act.    No act or failure to act by
the Board of Directors of the General Partner shall constitute a breach by
Energy Partners of this Agreement unless such act or failure to act is expressly
approved by the Conflicts Committee.

[Remainder of this page is intentionally left blank.]

45

--------------------------------------------------------------------------------

        IN WITNESS WHEREOF, the parties hereto have caused this instrument to be
executed in counterparts by their duly authorized officers, all as of the day
and year first above written.

    MARKWEST HYDROCARBON, INC.
 
 
By:
/s/  FRANK M. SEMPLE      

--------------------------------------------------------------------------------

Frank M. Semple
President
 
 
MARKWEST ENERGY PARTNERS, L.P.
 
 
 
By:
MarkWest Energy GP, L.L.C.,
its general partner
 
 
 
By:
/s/  NANCY K. BUESE      

--------------------------------------------------------------------------------

Nancy K. Buese
Chief Financial Officer
 
 
MWEP, L.L.C.
 
 
 
By:
MarkWest Energy Partners, L.P.,
its sole member       By: MarkWest Energy GP, L.L.C.,
its general partner
 
 
By:
/s/  NANCY K. BUESE      

--------------------------------------------------------------------------------

Nancy K. Buese
Chief Financial Officer

--------------------------------------------------------------------------------

Annex A

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

THIRD AMENDED AND RESTATED

AGREEMENT OF LIMITED PARTNERSHIP

OF

MARKWEST ENERGY PARTNERS, L.P.

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

TABLE OF CONTENTS

ARTICLE I
DEFINITIONS     Section 1.1   Definitions   A-1 Section 1.2   Construction  
A-11
ARTICLE II
ORGANIZATION
 
 
Section 2.1
 
Formation
 
A-11 Section 2.2   Name   A-11 Section 2.3   Registered Office; Registered
Agent; Principal Office; Other Offices   A-11 Section 2.4   Purpose and Business
  A-11 Section 2.5   Powers   A-12 Section 2.6   Power of Attorney   A-12
Section 2.7   Term   A-13 Section 2.8   Title to Partnership Assets   A-13
ARTICLE III
RIGHTS OF LIMITED PARTNERS
 
 
Section 3.1
 
Limitation of Liability
 
A-14 Section 3.2   Management of Business   A-14 Section 3.3   Outside
Activities of the Limited Partners   A-14 Section 3.4   Rights of Limited
Partners   A-14
ARTICLE IV
CERTIFICATES; RECORD HOLDERS; TRANSFER OF PARTNERSHIP INTERESTS; REDEMPTION OF
PARTNERSHIP INTERESTS
 
 
Section 4.1
 
Certificates
 
A-15 Section 4.2   Mutilated, Destroyed, Lost or Stolen Certificates   A-15
Section 4.3   Record Holders   A-16 Section 4.4   Transfer Generally   A-16
Section 4.5   Registration and Transfer of Limited Partner Interests   A-16
Section 4.6   Restrictions on Transfers   A-17 Section 4.7   Citizenship
Certificates; Non-citizen Assignees   A-18 Section 4.8   Redemption of
Partnership Interests of Non-citizen Assignees   A-18
ARTICLE V
CAPITAL CONTRIBUTIONS AND ISSUANCE OF PARTNERSHIP INTERESTS
 
 
Section 5.1
 
Contributions
 
A-19 Section 5.2   Interest and Withdrawal   A-19 Section 5.3   Capital Accounts
  A-20 Section 5.4   Issuances of Additional Partnership Securities   A-22
Section 5.5   Splits and Combinations   A-22 Section 5.6   Fully Paid and
Non-Assessable Nature of Limited Partner Interests   A-23
ARTICLE VI
ALLOCATIONS AND DISTRIBUTIONS
 
 
Section 6.1
 
Allocations for Capital Account Purposes
 
A-23 Section 6.2   Allocations for Tax Purposes.   A-25          

A-i

--------------------------------------------------------------------------------

Section 6.3   Distributions.   A-27
ARTICLE VII
MANAGEMENT AND OPERATION OF BUSINESS
 
 
Section 7.1
 
Corporate Governance
 
A-28 Section 7.2   Management   A-28 Section 7.3   Certificate of Limited
Partnership   A-29 Section 7.4   Restrictions on the General Partner's Authority
  A-29 Section 7.5   Reimbursement of the General Partner   A-30 Section 7.6  
Outside Activities   A-31 Section 7.7   Loans from the General Partner; Loans or
Contributions from the Partnership; Contracts with Affiliates; Certain
Restrictions on the General Partner   A-31
Section 7.8
 
Indemnification
 
A-32 Section 7.9   Liability of Indemnitees   A-33 Section 7.10   Other Matters
Concerning the General Partner   A-34 Section 7.11   Purchase or Sale of
Partnership Securities   A-34 Section 7.12   Reliance by Third Parties   A-34
ARTICLE VIII
BOOKS, RECORDS, ACCOUNTING AND REPORTS
 
 
Section 8.1
 
Records and Accounting
 
A-35 Section 8.2   Fiscal Year   A-35 Section 8.3   Reports   A-35
ARTICLE IX
TAX MATTERS
 
 
Section 9.1
 
Tax Returns and Information
 
A-36 Section 9.2   Tax Elections   A-36 Section 9.3   Tax Controversies   A-36
Section 9.4   Withholding   A-36
ARTICLE X
ADMISSION OF PARTNERS
 
 
Section 10.1
 
Admission of Substituted Limited Partner
 
A-37 Section 10.2   Admission of Additional Limited Partners   A-37 Section 10.3
  Amendment of Agreement and Certificate of Limited Partnership   A-37
ARTICLE XI
WITHDRAWAL OR REMOVAL OF PARTNERS
 
 
Section 11.1
 
No Withdrawal or Removal of the General Partner
 
A-38 Section 11.2   Withdrawal of Limited Partners   A-38
ARTICLE XII
DISSOLUTION AND LIQUIDATION
 
 
Section 12.1
 
Dissolution
 
A-38 Section 12.2   Liquidator   A-39 Section 12.3   Liquidation   A-39 Section
12.4   Cancellation of Certificate of Limited Partnership   A-40 Section 12.5  
Return of Contributions   A-40 Section 12.6   Waiver of Partition   A-40        
 

A-ii

--------------------------------------------------------------------------------

Section 12.7   Capital Account Restoration   A-40
ARTICLE XIII
AMENDMENT OF PARTNERSHIP AGREEMENT;
MEETINGS; RECORD DATE
 
 
Section 13.1
 
Amendment to be Adopted Solely by the General Partner
 
A-40 Section 13.2   Amendment Procedures   A-41 Section 13.3   Amendment
Requirements   A-41 Section 13.4   Common Unitholder Meetings   A-42 Section
13.5   Notice of a Meeting   A-44 Section 13.6   Record Date   A-44 Section 13.7
  Adjournment   A-44 Section 13.8   Waiver of Notice; Approval of Meeting;
Approval of Minutes   A-44 Section 13.9   Quorum   A-44 Section 13.10   Conduct
of a Meeting   A-45 Section 13.11   Action Without a Meeting   A-45 Section
13.12   Voting and Other Rights   A-46
ARTICLE XIV
MERGER
 
 
Section 14.1
 
Authority
 
A-46 Section 14.2   Procedure for Merger or Consolidation   A-46 Section 14.3  
Approval by Limited Partners of Merger or Consolidation   A-47 Section 14.4  
Certificate of Merger   A-48 Section 14.5   Effect of Merger   A-48
ARTICLE XV
GENERAL PROVISIONS
 
 
Section 15.1
 
Addresses and Notices
 
A-48 Section 15.2   Further Action   A-49 Section 15.3   Binding Effect   A-49
Section 15.4   Integration   A-49 Section 15.5   Creditors   A-49 Section 15.6  
Waiver   A-49 Section 15.7   Counterparts   A-49 Section 15.8   Applicable Law  
A-49 Section 15.9   Invalidity of Provisions   A-49 Section 15.10   Consent of
Partners   A-49

A-iii

--------------------------------------------------------------------------------

THIRD AMENDED AND RESTATED AGREEMENT OF LIMITED PARTNERSHIP OF
MARKWEST ENERGY PARTNERS, L.P.

        THIS THIRD AMENDED AND RESTATED AGREEMENT OF LIMITED PARTNERSHIP OF
MARKWEST ENERGY PARTNERS, L.P. dated effective as of                        ,
20    , is entered into by and among MarkWest Energy GP, L.L.C., a Delaware
limited liability company, as the General Partner and as the lawful agent and
attorney-in-fact for the Limited Partners, and MarkWest Hydrocarbon, Inc., a
Delaware corporation, together with any other Persons who become Partners in the
Partnership or parties hereto as provided herein.

WITNESSETH:

        WHEREAS, the Partnership was formed under the Delaware Act on
January 25, 2002;

        WHEREAS, in connection with the initial public offering of the
Partnership in May 2002, the General Partner and other parties thereto entered
into the First Amended and Restated Agreement;

        WHEREAS, on December 31, 2004, the General Partner effected Amendment
No.1 to the First Amended and Restated Agreement;

        WHEREAS, on June 10, 2005, the Partnership effected Amendment No. 2 to
the First Amended and Restated Agreement;

        WHEREAS, on February 28, 2007, the General Partner and other parties
thereto amended and restated the First Amended and Restated Agreement, Amendment
No. 1 and No. 2 in its entirety and entered into the Second Amended and Restated
Agreement;

        WHEREAS, MarkWest Hydrocarbon, Inc., MWEP, L.L.C., a Delaware limited
liability company and a wholly-owned subsidiary of the Partnership, and the
Partnership have entered into the Agreement and Plan of Redemption and Merger
dated September 5, 2007; and

        WHEREAS, the General Partner and the other parties hereto now desire to
amend and restate the Second Amended and Restated Agreement in its entirety in
the manner set forth in this Agreement, and all of the Partners join in this
Agreement to evidence their agreement to the terms of this amended and restated
instrument.

        NOW, THEREFORE, in consideration of the covenants, conditions and
agreements contained herein, the parties hereto hereby agree as follows:

ARTICLE I
DEFINITIONS

        Section 1.1    Definitions.    The following definitions shall be for
all purposes, unless otherwise clearly indicated to the contrary, applied to the
terms used in this Agreement.

        "Acquisition" means any transaction in which any Group Member acquires
(through an asset acquisition, merger, stock acquisition or other form of
investment) control over all or a portion of the assets, properties or business
of another Person for the purpose of increasing the operating capacity or
revenues of the Partnership Group from the operating capacity or revenues of the
Partnership Group existing immediately prior to such transaction.

        "Additional Limited Partner" means a Person admitted to the Partnership
as a Limited Partner pursuant to Section 10.2 and who is shown as such on the
books and records of the Partnership.

        "Adjusted Capital Account" means the Capital Account maintained for each
Partner as of the end of each fiscal year of the Partnership, (a) increased by
any amounts that such Partner is obligated to restore under the standards set by
Treasury Regulation Section 1.704-1(b)(2)(ii)(c) (or is deemed

A-1

--------------------------------------------------------------------------------

obligated to restore under Treasury Regulation Sections 1.704-2(g) and
1.704-2(i)(5)) and (b) decreased by (i) the amount of all losses and deductions
that, as of the end of such fiscal year, are reasonably expected to be allocated
to such Partner in subsequent years under Sections 704(e)(2) and 706(d) of the
Code and Treasury Regulation Section 1.751-1(b)(2)(ii), and (ii) the amount of
all distributions that, as of the end of such fiscal year, are reasonably
expected to be made to such Partner in subsequent years in accordance with the
terms of this Agreement or otherwise to the extent they exceed offsetting
increases to such Partner's Capital Account that are reasonably expected to
occur during (or prior to) the year in which such distributions are reasonably
expected to be made (other than increases as a result of a minimum gain
chargeback pursuant to Section 6.1(c)(i) or Section 6.1(c)(ii)). The foregoing
definition of Adjusted Capital Account is intended to comply with the provisions
of Treasury Regulation Section 1.704-1(b)(2)(ii)(d) and shall be interpreted
consistently therewith. The "Adjusted Capital Account" of a Partner in respect
of a General Partner Interest, a Common Unit, a Class A Unit or any other
specified interest in the Partnership shall be the amount which such Adjusted
Capital Account would be if such General Partner Interest, Common Unit, Class A
Unit or other interest in the Partnership were the only interest in the
Partnership held by such Partner from and after the date on which such General
Partner Interest, Common Unit, Class A Unit or other interest was first issued.

        "Adjusted Property" means any property the Carrying Value of which has
been adjusted pursuant to Section 5.3(d)(i) or 5.3(d)(ii).

        "Affiliate" means, with respect to any Person, any other Person that
directly or indirectly through one or more intermediaries controls, is
controlled by or is under common control with, the Person in question. As used
herein, the term "control" means the possession, direct or indirect, of the
power to direct or cause the direction of the management and policies of a
Person, whether through ownership of voting securities, by contract or
otherwise. "Affiliate" with respect to the General Partner shall not include the
Partnership for purposes of Section 7.8.

        "Agreed Allocation" means any allocation, other than a Required
Allocation, of an item of income, gain, loss or deduction pursuant to the
provisions of Section 6.1, including, without limitation, a Curative Allocation
(if appropriate to the context in which the term "Agreed Allocation" is used).

        "Agreed Value" of any Contributed Property means the fair market value
of such property or other consideration at the time of contribution as
determined by the General Partner using such reasonable method of valuation as
it may adopt. The General Partner shall, in its discretion, use such method as
it deems reasonable and appropriate to allocate the aggregate Agreed Value of
Contributed Properties contributed to the Partnership in a single or integrated
transaction among each separate property on a basis proportional to the fair
market value of each Contributed Property.

        "Agreement" means this Third Amended and Restated Agreement of Limited
Partnership of MarkWest Energy Partners, L.P., as it may be amended,
supplemented or restated from time to time.

        "APB 25" means Accounting Principles Board Opinion Number 25, an
accounting principle governing accounting for stock issued to employees.

        "Assignee" means a Non-citizen Assignee or a Person to whom one or more
Limited Partner Interests have been transferred in a manner permitted under this
Agreement and who has executed and delivered a Transfer Application as required
by this Agreement, but who has not been admitted as a Substituted Limited
Partner.

        "Associate" means, when used to indicate a relationship with any Person:
(a) any corporation or organization of which such Person is a director, officer
or partner or is, directly or indirectly, the owner of 20% or more of any class
of voting stock or other voting interest; (b) any trust or other estate in which
such Person has at least a 20% beneficial interest or as to which such Person
serves as trustee or

A-2

--------------------------------------------------------------------------------

in a similar fiduciary capacity; or (c) any relative or spouse of such Person,
or any relative of such spouse, who has the same principal residence as such
Person.

        "Available Cash" means, with respect to any Quarter ending prior to the
Liquidation Date:

        (a)   the sum of (i) all cash and cash equivalents of the Partnership
Group on hand at the end of such Quarter, and (ii) all additional cash and cash
equivalents of the Partnership Group (excluding MarkWest Hydrocarbon, Inc.) on
hand on the date of determination of Available Cash with respect to such Quarter
resulting from Working Capital Borrowings made subsequent to the end of such
Quarter, less

        (b)   the amount of any cash reserves that are necessary or appropriate
in the reasonable discretion of the General Partner to (i) provide for the
proper conduct of the business of the Partnership Group (including reserves for
future capital expenditures and for anticipated future credit needs of the
Partnership Group) subsequent to such Quarter, (ii) comply with applicable law
or any loan agreement, security agreement, mortgage, debt instrument or other
agreement or obligation to which any Group Member is a party or by which it is
bound or its assets are subject or (iii) provide funds for distributions under
Section 6.3 in respect of any one or more of the next four Quarters; provided,
however, that disbursements made by a Group Member or cash reserves established,
increased or reduced after the end of such Quarter but on or before the date of
determination of Available Cash with respect to such Quarter shall be deemed to
have been made, established, increased or reduced, for purposes of determining
Available Cash, within such Quarter if the General Partner so determines.

        Notwithstanding the foregoing, "Available Cash" shall not include any
Hydrocarbon Available Cash. "Available Cash" with respect to the Quarter in
which the Liquidation Date occurs and any subsequent Quarter shall equal zero.

        "Board of Directors" means the Board of Directors of the General Partner
(or comparable governing body of any successor to the General Partner or, if
established by the Board of Directors, the Board of Directors of the
Partnership).

        "Book-Tax Disparity" means with respect to any item of Contributed
Property or Adjusted Property, as of the date of any determination, the
difference between the Carrying Value of such Contributed Property or Adjusted
Property and the adjusted basis thereof for federal income tax purposes as of
such date. A Partner's share of the Partnership's Book-Tax Disparities in all of
its Contributed Property and Adjusted Property will be reflected by the
difference between such Partner's Capital Account balance as maintained pursuant
to Section 5.3 and the hypothetical balance of such Partner's Capital Account
computed as if it had been maintained strictly in accordance with federal income
tax accounting principles.

        "Business Day" means Monday through Friday of each week, except that a
legal holiday recognized as such by the government of the United States of
America or the State of Colorado shall not be regarded as a Business Day.

        "Capital Account" means the capital account maintained for a Partner
pursuant to Section 5.3. The "Capital Account" of a Partner in respect of a
Common Unit, a Class A Unit or any other Partnership Interest shall be the
amount which such Capital Account would be if such Common Unit, Class A Unit or
other Partnership Interest were the only interest in the Partnership held by
such Partner from and after the date on which such Common Unit, Class A Unit or
other Partnership Interest was first issued.

        "Capital Contribution" means any cash, cash equivalents or the Net
Agreed Value of Contributed Property that a Partner contributes to the
Partnership pursuant to this Agreement or the Contribution Agreement.

A-3

--------------------------------------------------------------------------------

        "Capital Improvement" means any (a) addition or improvement to the
capital assets owned by any Group Member or (b) acquisition of existing, or the
construction of new, capital assets (including, without limitation, natural gas
processing plants and natural gas liquids pipelines, fractionation plants and
storage and distribution facilities and related assets), in each case if such
addition, improvement, acquisition or construction is made to increase the
operating capacity or revenues of the Partnership Group from the operating
capacity or revenues of the Partnership Group existing immediately prior to such
addition, improvement, acquisition or construction.

        "Carrying Value" means (a) with respect to a Contributed Property, the
Agreed Value of such property reduced (but not below zero) by all depreciation,
amortization and cost recovery deductions charged to the Partners' and
Assignees' Capital Accounts in respect of such Contributed Property, and
(b) with respect to any other Partnership property, the adjusted basis of such
property for federal income tax purposes, all as of the time of determination.
The Carrying Value of any property shall be adjusted from time to time in
accordance with Sections 5.3(d)(i) and 5.3(d)(ii) and to reflect changes,
additions or other adjustments to the Carrying Value for dispositions and
acquisitions of Partnership properties, as deemed appropriate by the General
Partner.

        "Cause" means a court of competent jurisdiction has entered a final,
non-appealable judgment finding the General Partner liable for actual fraud,
gross negligence or willful or wanton misconduct in its capacity as a general
partner of the Partnership.

        "Certificate" means a certificate (i) substantially in the form of
Exhibit A to this Agreement, (ii) issued in global form in accordance with the
rules and regulations of the Depositary or (iii) in such other form as may be
adopted by the General Partner in its discretion, issued by the Partnership
evidencing ownership of one or more Common Units or a certificate, in such form
as may be adopted by the General Partner in its discretion, issued by the
Partnership evidencing ownership of one or more other Partnership Securities.

        "Certificate of Limited Partnership" means the Certificate of Limited
Partnership of the Partnership filed with the Secretary of State of the State of
Delaware as referenced in Section 2.1, as such Certificate of Limited
Partnership may be amended, supplemented or restated from time to time.

        "Citizenship Certification" means a properly completed certificate in
such form as may be specified by the General Partner by which an Assignee or a
Limited Partner certifies that he (and if he is a nominee holding for the
account of another Person, that to the best of his knowledge such other Person)
is an Eligible Citizen.

        "Class A Unit" means a Partnership Security representing a fractional
part of the Partnership Interests of all Limited Partners and Assignees (but
does not include Common Units), and having the rights and obligations specified
with respect to Class A Units in this Agreement, which shall be identical to the
rights and obligations of the Common Units except the Class A Units (i) will not
have the right to vote on, approve or disapprove, or otherwise consent or not
consent with respect to any matter (including mergers, share exchanges and
similar statutory authorizations) except as otherwise required by any
non-waivable provision of law, and (ii) will not share in any Hydrocarbon Items
or any Hydrocarbon Available Cash.

        "Closing Price" means, for any day, the last sale price on such day,
regular way, or in case no such sale takes place on such day, the average of the
closing bid and asked prices on such day, regular way, in either case as
reported in the principal consolidated transaction reporting system with respect
to securities listed or admitted for trading on the principal National
Securities Exchange (other than the Nasdaq Stock Market) on which such Limited
Partner Interests of such class are listed or admitted to trading or, if such
Limited Partner Interests of such class are not listed or admitted to trading on
any National Securities Exchange (other than the Nasdaq Stock Market), the last
quoted price on such day or, if not so quoted, the average of the high bid and
low asked prices on such day in the

A-4

--------------------------------------------------------------------------------

over-the-counter market, as reported by the Nasdaq Stock Market or such other
system then in use, or, if on any such day such Limited Partner Interests of
such class are not quoted by any such organization, the average of the closing
bid and asked prices on such day as furnished by a professional market maker
making a market in such Limited Partner Interests of such class selected by the
General Partner, or if on any such day no market maker is making a market in
such Limited Partner Interests of such class, the fair value of such Limited
Partner Interests on such day as determined reasonably and in good faith by the
General Partner.

        "Cobb Contribution" means the contribution made by the General Partner
in the amount of $1,660,000 as required by the Partnership to fund the
construction and completion of the New Cobb Plant.

        "Code" means the Internal Revenue Code of 1986, as amended and in effect
from time to time. Any reference herein to a specific section or sections of the
Code shall be deemed to include a reference to any corresponding provision of
successor law.

        "Commission" means the United States Securities and Exchange Commission.

        "Common Unit" means a Partnership Security representing a fractional
part of the Partnership Interests of all Limited Partners and Assignees, and
having the rights and obligations specified with respect to Common Units in this
Agreement, but does not include any Class A Units.

        "Contributed Property" means each property or other asset, in such form
as may be permitted by the Delaware Act, but excluding cash, contributed to the
Partnership. Once the Carrying Value of a Contributed Property is adjusted
pursuant to Section 5.3(d), such property shall no longer constitute a
Contributed Property, but shall be deemed an Adjusted Property.

        "Contribution Agreement" means that certain Contribution, Conveyance and
Assumption Agreement, dated as of May 24, 2002, among the General Partner, the
Partnership, the Operating Company, MarkWest Hydrocarbon, Inc. and certain other
parties, together with the additional conveyance documents and instruments
contemplated or referenced thereunder.

        "Curative Allocation" means any allocation of an item of income, gain,
deduction, loss or credit pursuant to the provisions of Section 6.1(c)(ix).

        "Current Market Price" means, as of any date of any class of Limited
Partner Interests, the average of the daily Closing Prices (as hereinafter
defined) per Limited Partner Interest of such class for the 20 consecutive
Trading Days immediately prior to such date.

        "Delaware Act" means the Delaware Revised Uniform Limited Partnership
Act, 6 Del C. Section 17-101, et seq., as amended, supplemented or restated from
time to time, and any successor to such statute.

        "Depositary" means, with respect to any Units issued in global form, The
Depository Trust Company and its successors and permitted assigns.

        "Directors" shall mean the members of the Board of Directors.

        "Economic Risk of Loss" has the meaning set forth in Treasury Regulation
Section 1.752-2(a).

        "Eligible Citizen" means a Person qualified to own interests in real
property in jurisdictions in which any Group Member does business or proposes to
do business from time to time, and whose status as a Limited Partner or Assignee
does not or would not subject such Group Member to a significant risk of
cancellation or forfeiture of any of its properties or any interest therein.

        "FAS 123R" means Statement of Financial Accounting Standards Number
123R, an accounting principle governing accounting for share based payments.

A-5

--------------------------------------------------------------------------------

        "First Amended and Restated Agreement" has the meaning assigned to such
term in Section 2.1.

        "Fully Diluted Basis" means, when calculating the number of Outstanding
Units for any period, a basis that includes, in addition to the Outstanding
Units, all Partnership Securities and options, rights, warrants and appreciation
rights relating to an equity interest in the Partnership (a) that are
convertible into or exercisable or exchangeable for Units that are senior to or
pari passu with the Common Units, (b) whose conversion, exercise or exchange
price is less than the Current Market Price on the date of such calculation, and
(c) that may be converted into or exercised or exchanged for such Units prior to
or during the Quarter following the end of the last Quarter contained in the
period for which the calculation is being made without the satisfaction of any
contingency beyond the control of the holder other than the payment of
consideration and the compliance with administrative mechanics applicable to
such conversion, exercise or exchange.

        "General Partner" means MarkWest Energy GP, L.L.C. and its successors
and permitted assigns as general partner of the Partnership.

        "General Partner Interest" means the management interest of the General
Partner in the Partnership in its capacity as a general partner. The General
Partner Interest does not have any rights to ownership, profit or any rights to
receive distribution from operations or the liquidation of the Partnership.

        "Group" means a Person that with or through any of its Affiliates or
Associates has any agreement, arrangement or understanding for the purpose of
acquiring, holding, voting (except voting pursuant to a revocable proxy or
consent given to such Person in response to a proxy or consent solicitation made
to 10 or more Persons) or disposing of any Partnership Securities with any other
Person that beneficially owns, or whose Affiliates or Associates beneficially
own, directly or indirectly, Partnership Securities.

        "Group Member" means a member of the Partnership Group.

        "Hydrocarbon Available Cash" means all cash and cash equivalents on hand
derived from or attributable to the Partnership's ownership of, or sale or other
disposition of, the shares of common stock of MarkWest Hydrocarbon, Inc.

        "Hydrocarbon Items" means the income, gains, losses, deductions and
credits which are attributable to the Partnership's ownership of, or sale or
other disposition of, the shares of common stock of MarkWest Hydrocarbon, Inc.

        "Incentive Distribution Rights" has the meaning assigned to such term in
Section 1.1 of the Second Amended and Restated Agreement.

        "Indemnitee" means (a) the General Partner, (b) any Person who is or was
an Affiliate of the General Partner, (c) any Person who is or was a member,
partner, officer, director, employee, agent or trustee of any Group Member, the
General Partner or any Affiliate of any Group Member, and (d) any Person who is
or was serving at the request of the General Partner or any Affiliate of the
General Partner as an officer, director, employee, member, partner, agent,
fiduciary or trustee of another Person; provided, however, that a Person shall
not be an Indemnitee by reason of providing, on a fee-for-services basis,
trustee, fiduciary or custodial services.

        "Limited Partner" means, unless the context otherwise requires, (a) a
holder of Common Units or Class A Units, except to the extent otherwise provided
herein, each Substituted Limited Partner and each Additional Limited Partner or
(b) solely for purposes of Articles V, VI, VII and IX, each Assignee; provided,
however, that when the term "Limited Partner" is used herein in the context of
any vote or other approval, including without limitation Articles XIII and XIV,
such term shall not, solely for such purpose, include any holder of Class A
Units except as may otherwise be required by any non-waivable provision of law.

A-6

--------------------------------------------------------------------------------

        "Limited Partner Interest" means the ownership interest of a Limited
Partner or Assignee in the Partnership, which may be evidenced by Common Units,
Class A Units or other Partnership Securities or a combination thereof or
interest therein, and includes any and all benefits to which such Limited
Partner or Assignee is entitled as provided in this Agreement, together with all
obligations of such Limited Partner or Assignee to comply with the terms and
provisions of this Agreement; provided, however, that when the term "Limited
Partner Interest" is used herein in the context of any vote or other approval,
including without limitation Articles XIII and XIV, such term shall not, solely
for such purpose, include any holder of Class A Units except as may otherwise be
required by any non-waivable provision of law.

        "Liquidation Date" means the date on which dissolution of the
Partnership occurs.

        "Liquidator" means one or more Persons selected by the General Partner
to perform the functions described in Section 12.2 as liquidating trustee of the
Partnership within the meaning of the Delaware Act.

        "Merger Agreement" has the meaning assigned to such term in
Section 14.1.

        "National Securities Exchange" means an exchange registered with the
Commission under Section 6(a) of the Securities Exchange Act of 1934, as
amended, supplemented or restated from time to time, and any successor to such
statute, or the Nasdaq Stock Market or any successor thereto.

        "Net Agreed Value" means, (a) in the case of any Contributed Property,
the Agreed Value of such property reduced by any liabilities either assumed by
the Partnership upon such contribution or to which such property is subject when
contributed, and (b) in the case of any property distributed to a Partner or
Assignee by the Partnership, the Partnership's Carrying Value of such property
(as adjusted pursuant to Section 5.3(d)(ii)) at the time such property is
distributed, reduced by any indebtedness either assumed by such Partner or
Assignee upon such distribution or to which such property is subject at the time
of distribution, in either case, as determined under Section 752 of the Code.

        "Net Income" means, for any taxable year, the excess, if any, of the
Partnership's items of income and gain for such taxable year. The items included
in the calculation of Net Income shall be determined in accordance with
Section 5.3(b) and shall not include any items specially allocated under
Sections 6.1(b) and 6.1(c).

        "Net Loss" means, for any taxable year, the excess, if any, of the
Partnership's items of loss and deduction for such taxable year. The items
included in the calculation of Net Loss shall be determined in accordance with
Section 5.3(b) and shall not include any items specially allocated under
Sections 6.1(b) and 6.1(c).

        "New Cobb Plant" means the Gas Extraction Plant designed to the
specifications contained in the Amended and Restated Agreement for Construction
and Removal (Cobb Plant) dated as of December 31, 2004 entered into between
MarkWest Hydrocarbon, Inc. and MarkWest Energy Appalachia, L.L.C., replacing and
superseding that certain Agreement for Construction and Removal dated
October 10, 2003.

        "Non-citizen Assignee" means a Person whom the General Partner has
determined in its discretion does not constitute an Eligible Citizen and as to
whose Partnership Interest the General Partner has become the Substituted
Limited Partner, pursuant to Section 4.7.

        "Nonrecourse Built-in Gain" means with respect to any Contributed
Properties or Adjusted Properties that are subject to a mortgage or pledge
securing a Nonrecourse Liability, the amount of any taxable gain that would be
allocated to the Partners pursuant to Sections 6.2(b)(i)(A), 6.2(b)(ii)(A) and
6.2(b)(iii) if such properties were disposed of in a taxable transaction in full
satisfaction of such liabilities and for no other consideration.

A-7

--------------------------------------------------------------------------------

        "Nonrecourse Deductions" means any and all items of loss, deduction or
expenditure (including, without limitation, any expenditure described in
Section 705(a)(2)(B) of the Code) that, in accordance with the principles of
Treasury Regulation Section 1.704-2(b), are attributable to a Nonrecourse
Liability.

        "Nonrecourse Liability" has the meaning set forth in Treasury Regulation
Section 1.752-1(a)(2).

        "Operating Company" means MarkWest Energy Operating Company, L.L.C., a
Delaware limited liability company, and any successors thereto.

        "Operating Company Agreement" means the Amended and Restated Limited
Liability Company Agreement of the Operating Company, as it may be amended,
supplemented or restated from time to time.

        "Opinion of Counsel" means a written opinion of counsel (who may be
regular counsel to the Partnership or the General Partner or any of its
Affiliates) acceptable to the General Partner in its reasonable discretion.

        "Outstanding" means, with respect to Partnership Securities, all
Partnership Securities that are issued by the Partnership and reflected as
outstanding on the Partnership's books and records as of the date of
determination; provided, however, that if at any time any Person or Group
beneficially owns 20% or more of any Outstanding Partnership Securities of any
class then Outstanding, all Partnership Securities owned by such Person or Group
shall not be voted on any matter and shall not be considered to be Outstanding
when sending notices of a meeting of Limited Partners to vote on any matter
(unless otherwise required by any non-waivable provision of law), calculating
required votes, determining the presence of a quorum or for other similar
purposes under this Agreement; provided, further, that the foregoing limitation
shall not apply to any Person or Group who acquired 20% or more of any
Partnership Securities issued by the Partnership with the prior approval of the
Board of Directors of the General Partner.

        "Partner Nonrecourse Debt" has the meaning set forth in Treasury
Regulation Section 1.704-2(b)(4).

        "Partner Nonrecourse Debt Minimum Gain" has the meaning set forth in
Treasury Regulation Section 1.704-2(i)(2).

        "Partner Nonrecourse Deductions" means any and all items of loss,
deduction or expenditure (including, without limitation, any expenditure
described in Section 705(a)(2)(B) of the Code) that, in accordance with the
principles of Treasury Regulation Section 1.704-2(i), are attributable to a
Partner Nonrecourse Debt.

        "Partners" means the General Partner and the Limited Partners.

        "Partnership" means MarkWest Energy Partners, L.P., a Delaware limited
partnership, and any successors thereto.

        "Partnership Group" means the Partnership, the Operating Company and any
Subsidiary of any such entity, treated as a single consolidated entity.

        "Partnership Interest" means an interest in the Partnership, which shall
include the Limited Partner Interests.

        "Partnership Minimum Gain" means that amount determined in accordance
with the principles of Treasury Regulation Section 1.704-2(d).

        "Partnership Security" means any class or series of equity interest in
the Partnership (but excluding any options, rights, warrants and appreciation
rights relating to an equity interest in the Partnership), including without
limitation, Common Units and Class A Units.

A-8

--------------------------------------------------------------------------------

        "Percentage Interest" means as of any date of determination (a) as to
any Unitholder or Assignee holding Units (Common Units and Class A Units), the
product obtained by multiplying (i) 100% less the percentage applicable to
paragraph (b) by (ii) the quotient obtained by dividing (A) the number of Units
(Common Units and Class A Units) held by such Unitholder or Assignee by (B) the
total number of all outstanding Units (Common Units and Class A Units), and
(b) as to the holders of additional Partnership Securities issued by the
Partnership in accordance with Section 5.4, the percentage established as a part
of such issuance. The Percentage Interest with respect to the General Partner
Interest shall at all times be zero.

        "Person" means an individual or a corporation, limited liability
company, partnership, joint venture, trust, unincorporated organization,
association, government agency or political subdivision thereof or other entity.

        "Per Unit Capital Amount" means, as of any date of determination, the
Capital Account, stated on a per Unit basis, underlying any Unit held by a
Person other than the General Partner or any Affiliate of the General Partner
who holds Units.

        "Pro Rata" means (a) when modifying Units or any class thereof,
apportioned equally among all designated Units in accordance with their relative
Percentage Interests and (b) when modifying Partners and Assignees, apportioned
among all Partners and Assignees in accordance with their relative Percentage
Interests.

        "Quarter" means, unless the context requires otherwise, a fiscal quarter
of the Partnership.

        "Recapture Income" means any gain recognized by the Partnership
(computed without regard to any adjustment required by Section 734 or
Section 743 of the Code) upon the disposition of any property or asset of the
Partnership, which gain is characterized as ordinary income because it
represents the recapture of deductions previously taken with respect to such
property or asset.

        "Record Date" means the date established by the General Partner for
determining (a) the identity of the Record Holders entitled to notice of, or to
vote at, any meeting of Limited Partners or entitled to vote by ballot or give
approval of Partnership action in writing without a meeting or entitled to
exercise rights in respect of any lawful action of Limited Partners or (b) the
identity of Record Holders entitled to receive any report or distribution or to
participate in any offer.

        "Record Holder" means the Person in whose name a Common Unit is
registered on the books of the Transfer Agent as of the opening of business on a
particular Business Day, or with respect to other Partnership Securities, the
Person in whose name any such other Partnership Security is registered on the
books which the General Partner has caused to be kept as of the opening of
business on such Business Day.

        "Redeemable Interests" means any Partnership Interests for which a
redemption notice has been given, and has not been withdrawn, pursuant to
Section 4.8.

        "Required Allocations" means any allocation of an item of income, gain,
loss or deduction pursuant to Section 6.1(c)(i), 6.1(c)(ii), 6.1(c)(iii),
6.1(c)(iv), 6.1(c)(vi) or 6.1(c)(viii).

        "Residual Gain" or "Residual Loss" means any item of gain or loss, as
the case may be, of the Partnership recognized for federal income tax purposes
resulting from a sale, exchange or other disposition of a Contributed Property
or Adjusted Property, to the extent such item of gain or loss is not allocated
pursuant to Section 6.2(b)(i) or 6.2(b)(ii), respectively, to eliminate Book-Tax
Disparities.

        "Second Amended and Restated Agreement" has the meaning assigned to such
term in Section 2.1.

        "Securities Act" means the Securities Act of 1933, as amended,
supplemented or restated from time to time and any successor to such statute.

A-9

--------------------------------------------------------------------------------

        "Subordinated Units" has the meaning assigned to such term in
Section 1.1 of the Second Amended and Restated Agreement.

        "Subsidiary" means, with respect to any Person, (a) a corporation of
which more than 50% of the voting power of shares entitled (without regard to
the occurrence of any contingency) to vote in the election of directors or other
governing body of such corporation is owned, directly or indirectly, at the date
of determination, by such Person, by one or more Subsidiaries of such Person or
a combination thereof, (b) a partnership (whether general or limited) in which
such Person or a Subsidiary of such Person is, at the date of determination, a
general or limited partner of such partnership, but only if more than 50% of the
partnership interests of such partnership (considering all of the partnership
interests of the partnership as a single class) is owned, directly or
indirectly, at the date of determination, by such Person, by one or more
Subsidiaries of such Person, or a combination thereof, or (c) any other Person
(other than a corporation or a partnership) in which such Person, one or more
Subsidiaries of such Person, or a combination thereof, directly or indirectly,
at the date of determination, has (i) at least a majority ownership interest or
(ii) the power to elect or direct the election of a majority of the directors or
other governing body of such Person.

        "Substituted Limited Partner" means a Person who is admitted as a
Limited Partner to the Partnership pursuant to Section 10.1 in place of and with
all the rights of a Limited Partner and who is shown as a Limited Partner on the
books and records of the Partnership.

        "Surviving Business Entity" has the meaning assigned to such term in
Section 14.2(b).

        "Trading Day" means a day on which the principal National Securities
Exchange on which such Limited Partner Interests of any class are listed or
admitted to trading is open for the transaction of business or, if Limited
Partner Interests of a class are not listed or admitted to trading on any
National Securities Exchange, a day on which banking institutions in New York
City generally are open.

        "Transfer" has the meaning assigned to such term in Section 4.4(a).

        "Transfer Agent" means such bank, trust company or other Person
(including the General Partner or one of its Affiliates) as shall be appointed
from time to time by the Partnership to act as registrar and transfer agent for
the Common Units; provided, however, that if no Transfer Agent is specifically
designated for any other Partnership Securities, the General Partner shall act
in such capacity.

        "Transfer Application" means an application and agreement for transfer
of Units in the form set forth on the back of a Certificate or in a form
substantially to the same effect in a separate instrument.

        "Unit" means a Partnership Security that is designated as a "Unit" and
shall include Common Units and Class A Units but shall not include the General
Partner Interest; provided, however, that when the term "Unit" is used herein in
the context of any vote or other approval, including without limitation
Article XIII and Article XIV, such term shall not, solely for such purpose,
include any holder of Class A Units except as otherwise required by any
non-waivable provision of law.

        "Unitholders" means the holders of Units.

        "Unrealized Gain" attributable to any item of Partnership property
means, as of any date of determination, the excess, if any, of (a) the fair
market value of such property as of such date (as determined under
Section 5.3(d)) over (b) the Carrying Value of such property as of such date
(prior to any adjustment to be made pursuant to Section 5.3(d) as of such date).

        "Unrealized Loss" attributable to any item of Partnership property
means, as of any date of determination, the excess, if any, of (a) the Carrying
Value of such property as of such date (prior to any adjustment to be made
pursuant to Section 5.3(d) as of such date) over (b) the fair market value of
such property as of such date (as determined under Section 5.3(d)).

        "U.S. GAAP" means United States Generally Accepted Accounting Principles
consistently applied.

A-10

--------------------------------------------------------------------------------

        "Voting Units" means all Units that are granted the right under this
Agreement or under the Delaware Act to vote with respect to the relevant matter.
Common Units constitute Voting Units, but Class A Units, the General Partner
Interests or any Partnership Securities owned, directly or indirectly, by the
Partnership do not constitute Voting Units.

        Section 1.2    Construction.    Unless the context requires otherwise:
(a) any pronoun used in this Agreement shall include the corresponding
masculine, feminine or neuter forms, and the singular form of nouns, pronouns
and verbs shall include the plural and vice versa; (b) references to Articles
and Sections refer to Articles and Sections of this Agreement; and (c) the term
"include" or "includes" means includes, without limitation, and "including"
means including, without limitation.

ARTICLE II
ORGANIZATION

        Section 2.1    Formation.    The General Partner and MarkWest
Hydrocarbon, Inc. have previously formed the Partnership as a limited
partnership pursuant to the provisions of the Delaware Act and hereby amend and
restate in its entirety the original Agreement of Limited Partnership of
MarkWest Energy Partners, L.P. as amended by that certain Amended and Restated
Agreement of Limited Partnership of MarkWest Energy Partners, L.P., dated as of
May 24, 2002 (the "First Amended and Restated Agreement"), as amended by that
certain Amendment No. 1, dated December 31, 2004, and Amendment No. 2, dated
June 10, 2005, to the First Amended and Restated Agreement, and that certain
Second Amended and Restated Agreement of Limited Partnership of MarkWest Energy
Partners, L.P., dated as of February 28, 2007 (the "Second Amended and Restated
Agreement"). This amendment and restatement shall become effective on the date
of this Agreement. Except as expressly provided to the contrary in this
Agreement, the rights, duties (including fiduciary duties), liabilities and
obligations of the Partners and the administration, dissolution and termination
of the Partnership shall be governed by the Delaware Act. All Partnership
Interests shall constitute personal property of the owner thereof for all
purposes and a Partner has no interest in specific Partnership property.

        Section 2.2    Name.    The name of the Partnership shall be "MarkWest
Energy Partners, L.P." The Partnership's business may be conducted under any
other name or names deemed necessary or appropriate by the General Partner in
its sole discretion, including the name of the General Partner. The words
"Limited Partnership," "L.P.," "Ltd." or similar words or letters shall be
included in the Partnership's name where necessary for the purpose of complying
with the laws of any jurisdiction that so requires. The General Partner in its
discretion may change the name of the Partnership at any time and from time to
time and shall notify the Limited Partners of such change in the next regular
communication to the Limited Partners.

        Section 2.3    Registered Office; Registered Agent; Principal Office;
Other Offices.    Unless and until changed by the General Partner, the
registered office of the Partnership in the State of Delaware shall be located
at 1209 Orange Street, Wilmington, Delaware 19801, and the registered agent for
service of process on the Partnership in the State of Delaware at such
registered office shall be The Corporation Trust Company. The principal office
of the Partnership shall be located at 1515 Arapahoe Street, Tower 2, Suite 700,
Denver, Colorado 80202 or such other place as the General Partner may from time
to time designate by notice to the Limited Partners. The Partnership may
maintain offices at such other place or places within or outside the State of
Delaware as the General Partner deems necessary or appropriate. The address of
the General Partner shall be 1515 Arapahoe Street, Tower 2, Suite 700, Denver,
Colorado 80202 or such other place as the General Partner may from time to time
designate by notice to the Limited Partners.

        Section 2.4    Purpose and Business.    The purpose and nature of the
business to be conducted by the Partnership shall be to (a) serve as a member of
the Operating Company and, in connection therewith, to exercise all the rights
and powers conferred upon the Partnership as a member of the

A-11

--------------------------------------------------------------------------------

Operating Company pursuant to the Operating Company Agreement or otherwise,
(b) engage directly in, or enter into or form any corporation, partnership,
joint venture, limited liability company or other arrangement to engage
indirectly in, any business activity that the Operating Company is permitted to
engage in by the Operating Company Agreement or that its Subsidiaries are
permitted to engage in by their limited liability company or partnership
agreements and, in connection therewith, to exercise all of the rights and
powers conferred upon the Partnership pursuant to the agreements relating to
such business activity, (c) engage directly in, or enter into or form any
corporation, partnership, joint venture, limited liability company or other
arrangement to engage indirectly in, any business activity that is approved by
the General Partner and which lawfully may be conducted by a limited partnership
organized pursuant to the Delaware Act and, in connection therewith, to exercise
all of the rights and powers conferred upon the Partnership pursuant to the
agreements relating to such business activity; provided, however, that the
General Partner reasonably determines, as of the date of the acquisition or
commencement of such activity, that such activity does not affect the
Partnership's treatment as a partnership for Federal income tax purposes, and
(d) do anything necessary or appropriate to the foregoing, including the making
of capital contributions or loans to a Group Member. The General Partner has no
obligation or duty to the Partnership, the Limited Partners or the Assignees to
propose or approve, and in its discretion may decline to propose or approve, the
conduct by the Partnership of any business.

        Section 2.5    Powers.    The Partnership shall be empowered to do any
and all acts and things necessary, appropriate, proper, advisable, incidental to
or convenient for the furtherance and accomplishment of the purposes and
business described in Section 2.4 and for the protection and benefit of the
Partnership.

        Section 2.6    Power of Attorney.    

        (a)   Each Limited Partner and each Assignee hereby constitutes and
appoints the General Partner and, if a Liquidator shall have been selected
pursuant to Section 12.2, the Liquidator (and any successor to the Liquidator by
merger, transfer, assignment, election or otherwise) and each of their
authorized officers and attorneys-in-fact, as the case may be, with full power
of substitution, as his true and lawful agent and attorney-in-fact, with full
power and authority in his name, place and stead, to:

          (i)  execute, swear to, acknowledge, deliver, file and record in the
appropriate public offices (A) all certificates, documents and other instruments
(including this Agreement and the Certificate of Limited Partnership and all
amendments or restatements hereof or thereof) that the General Partner or the
Liquidator deems necessary or appropriate to form, qualify or continue the
existence or qualification of the Partnership as a limited partnership (or a
partnership in which the limited partners have limited liability) in the State
of Delaware and in all other jurisdictions in which the Partnership may conduct
business or own property; (B) all certificates, documents and other instruments
that the General Partner or the Liquidator deems necessary or appropriate to
reflect, in accordance with its terms, any amendment, change, modification or
restatement of this Agreement; (C) all certificates, documents and other
instruments (including conveyances and a certificate of cancellation) that the
General Partner or the Liquidator deems necessary or appropriate to reflect the
dissolution and liquidation of the Partnership pursuant to the terms of this
Agreement; (D) all certificates, documents and other instruments relating to the
admission, withdrawal, removal or substitution of any Partner, as applicable,
pursuant to, or other events described in, Article IV, X, XI or XII; (E) all
certificates, documents and other instruments relating to the determination of
the rights, preferences and privileges of any class or series of Partnership
Securities issued pursuant to Section 5.4; and (F) all certificates, documents
and other instruments (including agreements and a certificate of merger)
relating to a merger or consolidation of the Partnership pursuant to
Article XIV; and

A-12

--------------------------------------------------------------------------------

         (ii)  execute, swear to, acknowledge, deliver, file and record all
ballots, consents, approvals, waivers, certificates, documents and other
instruments necessary or appropriate, in the discretion of the General Partner
or the Liquidator, to make, evidence, give, confirm or ratify any vote, consent,
approval, agreement or other action that is made or given by the Partners
hereunder or is consistent with the terms of this Agreement or is necessary or
appropriate, in the discretion of the General Partner or the Liquidator, to
effectuate the terms or intent of this Agreement; provided, however, that when
required by Section 13.3 or any other provision of this Agreement that
establishes a percentage of the Limited Partners or of the Limited Partners of
any class or series required to take any action, the General Partner and the
Liquidator may exercise the power of attorney made in this
Section 2.6(a)(ii) only after the necessary vote, consent or approval of the
Limited Partners or of the Limited Partners of such class or series, as
applicable.

Nothing contained in this Section 2.6(a) shall be construed as authorizing the
General Partner to amend this Agreement except in accordance with Article XIII
or as may be otherwise expressly provided for in this Agreement.

        (b)   The foregoing power of attorney is hereby declared to be
irrevocable and a power coupled with an interest, and it shall survive and, to
the maximum extent permitted by law, not be affected by the subsequent death,
incompetency, disability, incapacity, dissolution, bankruptcy or termination of
any Limited Partner or Assignee and the transfer of all or any portion of such
Limited Partner's or Assignee's Partnership Interest and shall extend to such
Limited Partner's or Assignee's heirs, successors, assigns and personal
representatives. Each such Limited Partner or Assignee hereby agrees to be bound
by any representation made by the General Partner or the Liquidator acting in
good faith pursuant to such power of attorney; and each such Limited Partner or
Assignee, to the maximum extent permitted by law, hereby waives any and all
defenses that may be available to contest, negate or disaffirm the action of the
General Partner or the Liquidator taken in good faith under such power of
attorney. Each Limited Partner or Assignee shall execute and deliver to the
General Partner or the Liquidator, within 15 days after receipt of the request
therefor, such further designation, powers of attorney and other instruments as
the General Partner or the Liquidator deems necessary to effectuate this
Agreement and the purposes of the Partnership.

        Section 2.7    Term.    The term of the Partnership commenced upon the
filing of the Certificate of Limited Partnership in accordance with the Delaware
Act and shall continue in existence until the dissolution of the Partnership in
accordance with the provisions of Article XII. The existence of the Partnership
as a separate legal entity shall continue until the cancellation of the
Certificate of Limited Partnership as provided in the Delaware Act.

        Section 2.8    Title to Partnership Assets.    Title to Partnership
assets, whether real, personal or mixed and whether tangible or intangible,
shall be deemed to be owned by the Partnership as an entity, and no Partner or
Assignee, individually or collectively, shall have any ownership interest in
such Partnership assets or any portion thereof. Title to any or all of the
Partnership assets may be held in the name of the Partnership, the General
Partner, one or more of its Affiliates or one or more nominees, as the General
Partner may determine. The General Partner hereby declares and warrants that any
Partnership assets for which record title is held in the name of the General
Partner or one or more of its Affiliates or one or more nominees shall be held
by the General Partner or such Affiliate or nominee for the use and benefit of
the Partnership in accordance with the provisions of this Agreement; provided,
however, that the General Partner shall use reasonable efforts to cause record
title to such assets (other than those assets in respect of which the General
Partner determines that the expense and difficulty of conveyancing makes
transfer of record title to the Partnership impracticable) to be vested in the
Partnership as soon as reasonably practicable; provided, further, that, prior to
the withdrawal of the General Partner or as soon thereafter as practicable, the
General Partner shall use reasonable efforts to effect the transfer of record
title to the Partnership and, prior to any such transfer, will provide for the
use of such assets in a manner satisfactory to the General Partner. All

A-13

--------------------------------------------------------------------------------

Partnership assets shall be recorded as the property of the Partnership in its
books and records, irrespective of the name in which record title to such
Partnership assets is held.

ARTICLE III
RIGHTS OF LIMITED PARTNERS

        Section 3.1    Limitation of Liability.    The Limited Partners and the
Assignees shall have no liability under this Agreement except as expressly
provided in this Agreement or the Delaware Act.

        Section 3.2    Management of Business.    No Limited Partner or
Assignee, in its capacity as such, shall participate in the operation,
management or control (within the meaning of the Delaware Act) of the
Partnership's business, transact any business in the Partnership's name or have
the power to sign documents for or otherwise bind the Partnership. Any action
taken by any Affiliate of the General Partner or any officer, director,
employee, manager, member, general partner, agent or trustee of the General
Partner or any of its Affiliates, or any officer, director, employee, member,
general partner, agent or trustee of a Group Member, in its capacity as such,
shall not be deemed to be participation in the control of the business of the
Partnership by a limited partner of the Partnership (within the meaning of
Section 17-303(a) of the Delaware Act) and shall not affect, impair or eliminate
the limitations on the liability of the Limited Partners or Assignees under this
Agreement.

        Section 3.3    Outside Activities of the Limited Partners.    Subject to
the provisions of Section 7.6, which shall continue to be applicable to the
Persons referred to therein, regardless of whether such Persons shall also be
Limited Partners or Assignees, any Limited Partner or Assignee shall be entitled
to and may have business interests and engage in business activities in addition
to those relating to the Partnership, including business interests and
activities in direct competition with the Partnership Group. Neither the
Partnership nor any of the other Partners or Assignees shall have any rights by
virtue of this Agreement in any business ventures of any Limited Partner or
Assignee.

        Section 3.4    Rights of Limited Partners.    

        (a)   In addition to other rights provided by this Agreement or by
applicable law, and except as limited by Section 3.4(b), each Limited Partner
shall have the right, for a purpose reasonably related to such Limited Partner's
interest as a limited partner in the Partnership, upon reasonable written demand
and at such Limited Partner's own expense:

          (i)  to obtain true and full information regarding the status of the
business and financial condition of the Partnership;

         (ii)  promptly after becoming available, to obtain a copy of the
Partnership's federal, state and local income tax returns for each year;

        (iii)  to have furnished to him a current list of the name and last
known business, residence or mailing address of each Partner;

        (iv)  to have furnished to him a copy of this Agreement and the
Certificate of Limited Partnership and all amendments thereto, together with a
copy of the executed copies of all powers of attorney pursuant to which this
Agreement, the Certificate of Limited Partnership and all amendments thereto
have been executed;

         (v)  to obtain true and full information regarding the amount of cash
and a description and statement of the Net Agreed Value of any other Capital
Contribution by each Partner and which each Partner has agreed to contribute in
the future, and the date on which each became a Partner; and

        (vi)  to obtain such other information regarding the affairs of the
Partnership as is just and reasonable.

A-14

--------------------------------------------------------------------------------

        (b)   The General Partner may keep confidential from the Limited
Partners and Assignees, for such period of time as the General Partner deems
reasonable, (i) any information that the General Partner reasonably believes to
be in the nature of trade secrets or (ii) other information the disclosure of
which the General Partner in good faith believes (A) is not in the best
interests of the Partnership Group, (B) could damage the Partnership Group or
(C) that any Group Member is required by law or by agreement with any third
party to keep confidential (other than agreements with Affiliates of the
Partnership the primary purpose of which is to circumvent the obligations set
forth in this Section 3.4).

ARTICLE IV
CERTIFICATES; RECORD HOLDERS; TRANSFER OF PARTNERSHIP
INTERESTS; REDEMPTION OF PARTNERSHIP INTERESTS

        Section 4.1    Certificates.    Upon the Partnership's issuance of
Common Units or Class A Units to any Person, the Partnership shall issue one or
more Certificates in the name of such Person evidencing the number of such Units
being so issued. In addition, upon the request of any Person owning Class A
Units or any other Partnership Securities other than Common Units, the
Partnership shall issue to such Person one or more certificates evidencing such
Class A Units or other Partnership Securities other than Common Units.
Certificates shall be executed on behalf of the Partnership by the Chairman of
the Board of Directors, President or any Executive Vice President or Vice
President and the Secretary or any Assistant Secretary of the General Partner.
No Common Unit Certificate shall be valid for any purpose until it has been
countersigned by the Transfer Agent; provided, however, that if the General
Partner elects to issue Common Units in global form, the Common Unit
Certificates shall be valid upon receipt of a certificate from the Transfer
Agent certifying that the Common Units have been duly registered in accordance
with the directions of the Partnership.

        Section 4.2    Mutilated, Destroyed, Lost or Stolen Certificates.    

        (a)   If any mutilated Certificate is surrendered to the Transfer Agent,
the appropriate officers of the General Partner on behalf of the Partnership
shall execute, and the Transfer Agent shall countersign and deliver in exchange
therefor, a new Certificate evidencing the same number and type of Partnership
Securities as the Certificate so surrendered.

        (b)   The appropriate officers of the General Partner on behalf of the
Partnership shall execute and deliver, and the Transfer Agent shall countersign,
a new Certificate in place of any Certificate previously issued if the Record
Holder of the Certificate:

          (i)  makes proof by affidavit, in form and substance satisfactory to
the General Partner, that a previously issued Certificate has been lost,
destroyed or stolen;

         (ii)  requests the issuance of a new Certificate before the General
Partner has notice that the Certificate has been acquired by a purchaser for
value in good faith and without notice of an adverse claim;

        (iii)  if requested by the General Partner, delivers to the General
Partner a bond, in form and substance satisfactory to the General Partner, with
surety or sureties and with fixed or open penalty as the General Partner may
reasonably direct, in its sole discretion, to indemnify the Partnership, the
Partners, the General Partner and the Transfer Agent against any claim that may
be made on account of the alleged loss, destruction or theft of the Certificate;
and

        (iv)  satisfies any other reasonable requirements imposed by the General
Partner.

        If a Limited Partner or Assignee fails to notify the General Partner
within a reasonable time after he has notice of the loss, destruction or theft
of a Certificate, and a transfer of the Limited Partner Interests represented by
the Certificate is registered before the Partnership, the General Partner or the
Transfer Agent receives such notification, the Limited Partner or Assignee shall
be precluded from making any claim against the Partnership, the General Partner
or the Transfer Agent for such transfer or for a new Certificate.

A-15

--------------------------------------------------------------------------------

        (c)   As a condition to the issuance of any new Certificate under this
Section 4.2, the General Partner may require the payment of a sum sufficient to
cover any tax or other governmental charge that may be imposed in relation
thereto and any other expenses (including the fees and expenses of the Transfer
Agent) reasonably connected therewith.

        Section 4.3    Record Holders.    The Partnership shall be entitled to
recognize the Record Holder as the Partner or Assignee with respect to any
Partnership Interest and, accordingly, shall not be bound to recognize any
equitable or other claim to or interest in such Partnership Interest on the part
of any other Person, regardless of whether the Partnership shall have actual or
other notice thereof, except as otherwise provided by law or any applicable
rule, regulation, guideline or requirement of any National Securities Exchange
on which such Partnership Interests are listed for trading. Without limiting the
foregoing, when a Person (such as a broker, dealer, bank, trust company or
clearing corporation or an agent of any of the foregoing) is acting as nominee,
agent or in some other representative capacity for another Person in acquiring
and/or holding Partnership Interests, as between the Partnership on the one
hand, and such other Persons on the other, such representative Person (a) shall
be the Partner or Assignee (as the case may be) of record and beneficially,
(b) must execute and deliver a Transfer Application and (c) shall be bound by
this Agreement and shall have the rights and obligations of a Partner or
Assignee (as the case may be) hereunder and as, and to the extent, provided for
herein.

        Section 4.4    Transfer Generally.    

        (a)   The term "transfer," when used in this Agreement with respect to a
Partnership Interest, shall be deemed to refer to a transaction by which the
General Partner assigns its General Partner Interest to another Person who then
becomes the general partner of the Partnership or by which the holder of a
Limited Partner Interest assigns such Limited Partner Interest to another Person
who is or becomes a Limited Partner or an Assignee, and includes a sale,
assignment, gift, pledge, encumbrance, hypothecation, mortgage, exchange or any
other disposition by law or otherwise.

        (b)   No Partnership Interest shall be transferred, in whole or in part,
except in accordance with the terms and conditions set forth in this Article IV.
Any transfer or purported transfer of a Partnership Interest not made in
accordance with this Article IV shall be null and void.

        (c)   Nothing contained in this Agreement shall be construed to prevent
a disposition by any member of the General Partner (other than MarkWest
Hydrocarbon, Inc., its direct and indirect Subsidiaries and the Partnership) of
any or all of the membership interests of the General Partner; provided,
however, the General Partner shall not dispose of any of its Partnership
Interests; provided, further, the General Partner may distribute its holdings of
Class A Units to its members.

        Section 4.5    Registration and Transfer of Limited Partner
Interests.    

        (a)   The General Partner shall keep or cause to be kept on behalf of
the Partnership a register in which, subject to such reasonable regulations as
it may prescribe and subject to the provisions of Section 4.5(b), the
Partnership will provide for the registration and transfer of Limited Partner
Interests. The Transfer Agent is hereby appointed registrar and transfer agent
for the purpose of registering Common Units and transfers of such Common Units
as herein provided. The Partnership shall not recognize transfers of
Certificates evidencing Limited Partner Interests unless such transfers are
effected in the manner described in this Section 4.5. Upon surrender of a
Certificate for registration of transfer of any Limited Partner Interests
evidenced by a Certificate, and subject to the provisions of Section 4.5(b), the
appropriate officers of the General Partner on behalf of the Partnership shall
execute and deliver, and in the case of Common Units, the Transfer Agent shall
countersign and deliver, in the name of the holder or the designated transferee
or transferees, as required pursuant to the holder's instructions, one or more
new Certificates evidencing the same aggregate number and type of Limited
Partner Interests as was evidenced by the Certificate so surrendered.

A-16

--------------------------------------------------------------------------------

        (b)   Except as otherwise provided in Section 4.7, the General Partner
shall not recognize any transfer of Limited Partner Interests until the
Certificates evidencing such Limited Partner Interests are surrendered for
registration of transfer and such Certificates are accompanied by a Transfer
Application duly executed by the transferee (or the transferee's
attorney-in-fact duly authorized in writing). No charge shall be imposed by the
General Partner for such transfer; provided, however, that as a condition to the
issuance of any new Certificate under this Section 4.5, the General Partner may
require the payment of a sum sufficient to cover any tax or other governmental
charge that may be imposed with respect thereto.

        (c)   Limited Partner Interests may be transferred only in the manner
described in this Section 4.5. The transfer of any Limited Partner Interests and
the admission of any new Limited Partner shall not constitute an amendment to
this Agreement.

        (d)   Until admitted as a Substituted Limited Partner pursuant to
Section 10.1, the Record Holder of a Limited Partner Interest shall be an
Assignee in respect of such Limited Partner Interest. Limited Partners may
include custodians, nominees or any other individual or entity in its own or any
representative capacity.

        (e)   A transferee of a Limited Partner Interest who has completed and
delivered a Transfer Application shall be deemed to have (i) requested admission
as a Substituted Limited Partner, (ii) agreed to comply with and be bound by and
to have executed this Agreement, (iii) represented and warranted that such
transferee has the right, power and authority and, if an individual, the
capacity to enter into this Agreement, (iv) granted the powers of attorney set
forth in this Agreement and (v) given the consents and approvals and made the
waivers contained in this Agreement.

        Section 4.6    Restrictions on Transfers.    

        (a)   Except as provided in Section 4.6(c) below, but notwithstanding
the other provisions of this Article IV, no transfer of any Partnership
Interests shall be made if such transfer would (i) violate the then applicable
federal or state securities laws or rules and regulations of the Commission, any
state securities commission or any other governmental authority with
jurisdiction over such transfer, (ii) terminate the existence or qualification
of the Partnership or the Operating Company under the laws of the jurisdiction
of its formation, or (iii) cause the Partnership or the Operating Company to be
treated as an association taxable as a corporation or otherwise to be taxed as
an entity for federal income tax purposes (to the extent not already so treated
or taxed).

        (b)   The General Partner may impose restrictions on the transfer of
Partnership Interests if a subsequent Opinion of Counsel determines that such
restrictions are necessary to avoid a significant risk of any Group Member
becoming taxable as a corporation or otherwise to be taxed as an entity for
federal income tax purposes. The restrictions may be imposed by making such
amendments to this Agreement as the General Partner may determine to be
necessary or appropriate to impose such restrictions; provided, however, that
any amendment that the General Partner believes, in the exercise of its
reasonable discretion, could result in the delisting or suspension of trading of
any class of Limited Partner Interests on the principal National Securities
Exchange on which such class of Limited Partner Interests is then traded must be
approved, prior to such amendment being effected, by the holders of at least a
majority of the Outstanding Limited Partner Interests of such class.

        (c)   Nothing contained in this Article IV, or elsewhere in this
Agreement, shall preclude the settlement of any transactions involving
Partnership Interests entered into through the facilities of any National
Securities Exchange on which such Partnership Interests are listed for trading.

        (d)   The General Partner Interest shall not be transferred to any
Person for any reason whatsoever. So long as the Partnership is a limited
partnership, 100% of the General Partner Interests, if any, shall be owned,
beneficially and of record, by the Partnership or one of more of its wholly
owned subsidiaries.

A-17

--------------------------------------------------------------------------------

        Section 4.7    Citizenship Certificates; Non-citizen Assignees.    

        (a)   If any Group Member is or becomes subject to any federal, state or
local law or regulation that, in the reasonable determination of the General
Partner, creates a substantial risk of cancellation or forfeiture of any
property in which the Group Member has an interest based on the nationality,
citizenship or other related status of a Limited Partner or Assignee, the
General Partner may request any Limited Partner or Assignee to furnish to the
General Partner, within 30 days after receipt of such request, an executed
Citizenship Certification or such other information concerning his nationality,
citizenship or other related status (or, if the Limited Partner or Assignee is a
nominee holding for the account of another Person, the nationality, citizenship
or other related status of such Person) as the General Partner may request. If a
Limited Partner or Assignee fails to furnish to the General Partner within the
aforementioned 30-day period such Citizenship Certification or other requested
information or if upon receipt of such Citizenship Certification or other
requested information the General Partner determines, with the advice of
counsel, that a Limited Partner or Assignee is not an Eligible Citizen, the
Partnership Interests owned by such Limited Partner or Assignee shall be subject
to redemption in accordance with the provisions of Section 4.8. In addition, the
General Partner may require that the status of any such Partner or Assignee be
changed to that of a Non-citizen Assignee and, thereupon, the General Partner
shall be substituted for such Non-citizen Assignee as the Limited Partner in
respect of his Limited Partner Interests.

        (b)   The General Partner shall, in exercising voting rights in respect
of Limited Partner Interests held by it on behalf of Non-citizen Assignees,
distribute the votes in the same ratios as the votes of Partners (including
without limitation the General Partner) in respect of Limited Partner Interests
other than those of Non-citizen Assignees are cast, either for, against or
abstaining as to the matter.

        (c)   Upon dissolution of the Partnership, a Non-citizen Assignee shall
have no right to receive a distribution in kind pursuant to Section 12.3 but
shall be entitled to the cash equivalent thereof, and the Partnership shall
provide cash in exchange for an assignment of the Non-citizen Assignee's share
of the distribution in kind. Such payment and assignment shall be treated for
Partnership purposes as a purchase by the Partnership from the Non-citizen
Assignee of his Limited Partner Interest (representing his right to receive his
share of such distribution in kind).

        (d)   At any time after he can and does certify that he has become an
Eligible Citizen, a Non-citizen Assignee may, upon application to the General
Partner, request admission as a Substituted Limited Partner with respect to any
Limited Partner Interests of such Non-citizen Assignee not redeemed pursuant to
Section 4.8, and upon his admission pursuant to Section 10.1, the General
Partner shall cease to be deemed to be the Limited Partner in respect of the
Non-citizen Assignee's Limited Partner Interests.

        Section 4.8    Redemption of Partnership Interests of Non-citizen
Assignees.    

        (a)   If at any time a Limited Partner or Assignee fails to furnish a
Citizenship Certification or other information requested within the 30-day
period specified in Section 4.7(a), or if upon receipt of such Citizenship
Certification or other information the General Partner determines, with the
advice of counsel, that a Limited Partner or Assignee is not an Eligible
Citizen, the Partnership may, unless the Limited Partner or Assignee establishes
to the satisfaction of the General Partner that such Limited Partner or Assignee
is an Eligible Citizen or has transferred his Partnership Interests to a Person
who is an Eligible Citizen and who furnishes a Citizenship Certification to the
General Partner prior to the date fixed for redemption as provided below, redeem
the Partnership Interest of such Limited Partner or Assignee as follows:

          (i)  The General Partner shall, not later than the 30th day before the
date fixed for redemption, give notice of redemption to the Limited Partner or
Assignee, at his last address designated on the records of the Partnership or
the Transfer Agent, by registered or certified mail,

A-18

--------------------------------------------------------------------------------

postage prepaid. The notice shall be deemed to have been given when so mailed.
The notice shall specify the Redeemable Interests, the date fixed for
redemption, the place of payment, that payment of the redemption price will be
made upon surrender of the Certificate evidencing the Redeemable Interests and
that on and after the date fixed for redemption no further allocations or
distributions to which the Limited Partner or Assignee would otherwise be
entitled in respect of the Redeemable Interests will accrue or be made.

         (ii)  The aggregate redemption price for Redeemable Interests shall be
an amount equal to the Current Market Price (the date of determination of which
shall be the date fixed for redemption) of Limited Partner Interests of the
class to be so redeemed multiplied by the number of Limited Partner Interests of
each such class included among the Redeemable Interests. The redemption price
shall be paid, in the discretion of the General Partner, in cash or by delivery
of a promissory note of the Partnership in the principal amount of the
redemption price, bearing interest at the rate of 10% annually and payable in
three equal annual installments of principal together with accrued interest,
commencing one year after the redemption date.

        (iii)  Upon surrender by or on behalf of the Limited Partner or
Assignee, at the place specified in the notice of redemption, of the Certificate
evidencing the Redeemable Interests, duly endorsed in blank or accompanied by an
assignment duly executed in blank, the Limited Partner or Assignee or his duly
authorized representative shall be entitled to receive the payment therefor.

        (iv)  After the redemption date, Redeemable Interests shall no longer
constitute issued and Outstanding Limited Partner Interests.

        (b)   The provisions of this Section 4.8 shall also be applicable to
Limited Partner Interests held by a Limited Partner or Assignee as nominee of a
Person determined to be other than an Eligible Citizen.

        (c)   Nothing in this Section 4.8 shall prevent the recipient of a
notice of redemption from transferring his Limited Partner Interest before the
redemption date if such transfer is otherwise permitted under this Agreement.
Upon receipt of notice of such a transfer, the General Partner shall withdraw
the notice of redemption, provided the transferee of such Limited Partner
Interest certifies to the satisfaction of the General Partner in a Citizenship
Certification delivered in connection with the Transfer Application that he is
an Eligible Citizen. If the transferee fails to make such certification, such
redemption shall be effected from the transferee on the original redemption
date.

ARTICLE V
CAPITAL CONTRIBUTIONS AND ISSUANCE OF PARTNERSHIP INTERESTS

        Section 5.1    Contributions.    On the date hereof, the Partnership:
(i) issued 18,506,132 Class A Units to the General Partner in exchange for
(A) the General Partner Interest constituting the 2% economic interest (but not
the other rights, privileges and obligations related to the General Partner
Interest), which represented the right to be allocated 2% of the income, gains,
losses and deductions of the Partnership and to receive 2% of the distributions
made by the Partnership and (B) the Incentive Distribution Rights; (ii) issued
5,900,000 Class A Units to MarkWest Hydrocarbon, Inc. in exchange for 4,938,992
Common Units, which represented all of its holdings of the Common Units; and
(iii) cancelled such portion of the General Partner Interest, the Incentive
Distribution Rights and the Common Units.

        Section 5.2    Interest and Withdrawal.    No interest shall be paid by
the Partnership on Capital Contributions. No Partner or Assignee shall be
entitled to the withdrawal or return of its Capital Contribution, except to the
extent, if any, that distributions made pursuant to this Agreement or upon
termination of the Partnership may be considered as such by law and then only to
the extent provided for in this Agreement. Except to the extent expressly
provided in this Agreement, no Partner or Assignee shall have priority over any
other Partner or Assignee either as to the return of Capital

A-19

--------------------------------------------------------------------------------

Contributions or as to profits, losses or distributions. Any such return shall
be a compromise to which all Partners and Assignees agree within the meaning of
Section 17-502(b) of the Delaware Act.

        Section 5.3    Capital Accounts.    

        (a)   The Partnership shall maintain for each Limited Partner (or a
beneficial owner of Partnership Interests held by a nominee in any case in which
the nominee has furnished the identity of such owner to the Partnership in
accordance with Section 6031(c) of the Code or any other method acceptable to
the General Partner in its sole discretion) owning a Partnership Interest a
separate Capital Account with respect to such Partnership Interest in accordance
with the rules of Treasury Regulation Section 1.704-1(b)(2)(iv). Such Capital
Account shall be increased by (i) the amount of all Capital Contributions made
to the Partnership with respect to such Partnership Interest pursuant to this
Agreement and (ii) all items of Partnership income and gain (including, without
limitation, income and gain exempt from tax) computed in accordance with
Section 5.3(b) and allocated with respect to such Partnership Interest pursuant
to Section 6.1, and decreased by (x) the amount of cash or Net Agreed Value of
all actual and deemed distributions of cash or property made with respect to
such Partnership Interest pursuant to this Agreement and (y) all items of
Partnership deduction and loss computed in accordance with Section 5.3(b) and
allocated with respect to such Partnership Interest pursuant to Section 6.1.

        (b)   For purposes of computing the amount of any item of income, gain,
loss or deduction which is to be allocated pursuant to Article VI and is to be
reflected in the Partners' Capital Accounts, the determination, recognition and
classification of any such item shall be the same as its determination,
recognition and classification for federal income tax purposes (including,
without limitation, any method of depreciation, cost recovery or amortization
used for that purpose), provided, that:

          (i)  Solely for purposes of this Section 5.3, the Partnership shall be
treated as owning directly its proportionate share (as determined by the General
Partner based upon the provisions of the Operating Company Agreement) of all
property owned by the Operating Company or any other Subsidiary that is
classified as a partnership for federal income tax purposes.

         (ii)  All fees and other expenses incurred by the Partnership to
promote the sale of (or to sell) a Partnership Interest that can neither be
deducted nor amortized under Section 709 of the Code, if any, shall, for
purposes of Capital Account maintenance, be treated as an item of deduction at
the time such fees and other expenses are incurred and shall be allocated among
the Partners pursuant to Section 6.1.

        (iii)  Except as otherwise provided in Treasury Regulation
Section 1.704-1(b)(2)(iv)(m), the computation of all items of income, gain, loss
and deduction shall be made without regard to any election under Section 754 of
the Code which may be made by the Partnership and, as to those items described
in Section 705(a)(1)(B) or 705(a)(2)(B) of the Code, without regard to the fact
that such items are not includable in gross income or are neither currently
deductible nor capitalized for federal income tax purposes. To the extent an
adjustment to the adjusted tax basis of any Partnership asset pursuant to
Section 734(b) or 743(b) of the Code is required, pursuant to Treasury
Regulation Section 1.704-1(b)(2)(iv)(m), to be taken into account in determining
Capital Accounts, the amount of such adjustment in the Capital Accounts shall be
treated as an item of gain or loss.

        (iv)  Any income, gain or loss attributable to the taxable disposition
of any Partnership property shall be determined as if the adjusted basis of such
property as of such date of disposition were equal in amount to the
Partnership's Carrying Value with respect to such property as of such date.

         (v)  In accordance with the requirements of Section 704(b) of the Code,
any deductions for depreciation, cost recovery or amortization attributable to
any Contributed Property shall be

A-20

--------------------------------------------------------------------------------

determined as if the adjusted basis of such property on the date it was acquired
by the Partnership were equal to the Agreed Value of such property. Upon an
adjustment pursuant to Section 5.3(d) to the Carrying Value of any Partnership
property subject to depreciation, cost recovery or amortization, any further
deductions for such depreciation, cost recovery or amortization attributable to
such property shall be determined (A) as if the adjusted basis of such property
were equal to the Carrying Value of such property immediately following such
adjustment and (B) using a rate of depreciation, cost recovery or amortization
derived from the same method and useful life (or, if applicable, the remaining
useful life) as is applied for federal income tax purposes; provided, however,
that, if the asset has a zero adjusted basis for federal income tax purposes,
depreciation, cost recovery or amortization deductions shall be determined using
any reasonable method that the General Partner may adopt.

        (vi)  If the Partnership's adjusted basis in a depreciable or cost
recovery property is reduced for federal income tax purposes pursuant to
Section 48(q)(1) or 48(q)(3) of the Code, the amount of such reduction shall,
solely for purposes hereof, be deemed to be an additional depreciation or cost
recovery deduction in the year such property is placed in service and shall be
allocated among the Partners pursuant to Section 6.1. Any restoration of such
basis pursuant to Section 48(q)(2) of the Code shall, to the extent possible, be
allocated in the same manner to the Partners to whom such deemed deduction was
allocated.

        (c)   A transferee of a Partnership Interest shall succeed to a pro rata
portion of the Capital Account of the transferor relating to the Partnership
Interest so transferred.

        (d)   (i) In accordance with Treasury Regulation
Section 1.704-1(b)(2)(iv)(f), on an issuance of additional Partnership Interests
for cash or Contributed Property, the Capital Account of all Partners and the
Carrying Value of each Partnership property immediately prior to such issuance
shall be adjusted upward or downward to reflect any Unrealized Gain or
Unrealized Loss attributable to such Partnership property, as if such Unrealized
Gain or Unrealized Loss had been recognized on an actual sale of each such
property immediately prior to such issuance and had been allocated to the
Partners at such time pursuant to Section 6.1 in the same manner as any item of
gain or loss actually recognized during such period would have been allocated.
In determining such Unrealized Gain or Unrealized Loss, the aggregate cash
amount and fair market value of all Partnership assets (including, without
limitation, cash or cash equivalents) immediately prior to the issuance of
additional Partnership Interests shall be determined by the General Partner
using such reasonable method of valuation as it may adopt; provided, however,
that the General Partner, in arriving at such valuation, must take fully into
account the fair market value of the Partnership Interests of all Partners at
such time. The General Partner shall allocate such aggregate value among the
assets of the Partnership (in such manner as it determines in its discretion to
be reasonable) to arrive at a fair market value for individual properties.

         (ii)  In accordance with Treasury Regulation
Section 1.704-1(b)(2)(iv)(f), immediately prior to any actual or deemed
distribution to a Partner of any Partnership property (other than a distribution
of cash that is not in redemption or retirement of a Partnership Interest), the
Capital Accounts of all Partners and the Carrying Value of all Partnership
property shall be adjusted upward or downward to reflect any Unrealized Gain or
Unrealized Loss attributable to such Partnership property, as if such Unrealized
Gain or Unrealized Loss had been recognized in a sale of such property
immediately prior to such distribution for an amount equal to its fair market
value, and had been allocated to the Partners, at such time, pursuant to
Section 6.1 in the same manner as any item of gain or loss actually recognized
during such period would have been allocated. In determining such Unrealized
Gain or Unrealized Loss the aggregate cash amount and fair market value of all
Partnership assets (including, without limitation, cash or cash equivalents)
immediately prior to a distribution shall (A) in the case of an actual
distribution which is not made pursuant to Section 12.3 or in the case of a
deemed distribution, be determined and allocated in

A-21

--------------------------------------------------------------------------------

the same manner as that provided in Section 5.3(d)(i) or (B) in the case of a
liquidating distribution pursuant to Section 12.3, be determined and allocated
by the Liquidator using such reasonable method of valuation as it may adopt.

        Section 5.4    Issuances of Additional Partnership Securities.    

        (a)   The Partnership may issue additional Partnership Securities and
options, rights, warrants and appreciation rights relating to the Partnership
Securities for any Partnership purpose at any time and from time to time to such
Persons for such consideration and on such terms and conditions as shall be
established by the General Partner in its sole discretion, all without the
approval of any Limited Partners.

        (b)   Each additional Partnership Security authorized to be issued by
the Partnership pursuant to Section 5.4(a) may be issued in one or more classes,
or one or more series of any such classes, with such designations, preferences,
rights, powers and duties (which may be senior to existing classes and series of
Partnership Securities), as shall be fixed by the General Partner in the
exercise of its sole discretion, including (i) the right to share Partnership
profits and losses or items thereof; (ii) the right to share in Partnership
distributions; (iii) the rights upon dissolution and liquidation of the
Partnership; (iv) whether, and the terms and conditions upon which, the
Partnership may redeem the Partnership Security; (v) whether such Partnership
Security is issued with the privilege of conversion or exchange and, if so, the
terms and conditions of such conversion or exchange; (vi) the terms and
conditions upon which each Partnership Security will be issued, evidenced by
certificates and assigned or transferred; and (vii) the right, if any, of each
such Partnership Security to vote on Partnership matters, including matters
relating to the relative rights, preferences and privileges of such Partnership
Security.

        (c)   The General Partner is hereby authorized and directed to take all
actions that it deems necessary or appropriate in connection with (i) each
issuance of Partnership Securities and options, rights, warrants and
appreciation rights relating to Partnership Securities pursuant to this
Section 5.4, (ii) the admission of Additional Limited Partners and (iii) all
additional issuances of Partnership Securities. The General Partner is further
authorized and directed to specify the relative rights, powers and duties of the
holders of the Units or other Partnership Securities being so issued. The
General Partner shall do all things necessary to comply with the Delaware Act
and is authorized and directed to do all things it deems to be necessary or
advisable in connection with any future issuance of Partnership Securities or in
connection with the conversion of the General Partner Interest into Units
pursuant to the terms of this Agreement, including compliance with any statute,
rule, regulation or guideline of any federal, state or other governmental agency
or any National Securities Exchange on which the Units or other Partnership
Securities are listed for trading.

        (d)   No fractional Units shall be issued by the Partnership.

        Section 5.5    Splits and Combinations.    

        (a)   Subject to Section 5.5(d), the Partnership may make a Pro Rata
distribution of Partnership Securities to all Record Holders or may effect a
subdivision or combination of Partnership Securities so long as, after any such
event, each Partner shall have the same Percentage Interest in the Partnership
as before such event, and any amounts calculated on a per Unit basis or stated
as a number of Units are proportionately adjusted retroactive to the beginning
of the Partnership.

        (b)   Whenever such a distribution, subdivision or combination of
Partnership Securities is declared, the General Partner shall select a Record
Date as of which the distribution, subdivision or combination shall be effective
and shall send notice thereof at least 20 days prior to such Record Date to each
Record Holder as of a date not less than 10 days prior to the date of such
notice. The General Partner also may cause a firm of independent public
accountants selected by it to calculate the number of Partnership Securities to
be held by each Record Holder after giving effect to such distribution,

A-22

--------------------------------------------------------------------------------

subdivision or combination. The General Partner shall be entitled to rely on any
certificate provided by such firm as conclusive evidence of the accuracy of such
calculation.

        (c)   Promptly following any such distribution, subdivision or
combination, the Partnership may issue Certificates to the Record Holders of
Partnership Securities as of the applicable Record Date representing the new
number of Partnership Securities held by such Record Holders, or the General
Partner may adopt such other procedures as it may deem appropriate to reflect
such changes. If any such combination results in a smaller total number of
Partnership Securities Outstanding, the Partnership shall require, as a
condition to the delivery to a Record Holder of such new Certificate, the
surrender of any Certificate held by such Record Holder immediately prior to
such Record Date.

        (d)   The Partnership shall not issue fractional Units upon any
distribution, subdivision or combination of Units. If a distribution,
subdivision or combination of Units would result in the issuance of fractional
Units but for the provisions of Section 5.4(d) and this Section 5.5(d), each
fractional Unit shall be rounded to the nearest whole Unit (and a 0.5 Unit shall
be rounded to the next higher Unit).

        Section 5.6    Fully Paid and Non-Assessable Nature of Limited Partner
Interests.    All Limited Partner Interests issued pursuant to, and in
accordance with the requirements of, this Article V shall be fully paid and
non-assessable Limited Partner Interests in the Partnership, except as such
non-assessability may be affected by Section 17-607 of the Delaware Act.

ARTICLE VI
ALLOCATIONS AND DISTRIBUTIONS

        Section 6.1    Allocations for Capital Account Purposes.    For purposes
of maintaining the Capital Accounts and in determining the rights of the
Partners among themselves, the Partnership's items of income, gain, loss and
deduction (computed in accordance with Section 5.3(b)) shall be allocated among
the Partners in each taxable year (or portion thereof) as provided herein below.

        (a)    Net Income and Net Loss.    After giving effect to the special
allocations set forth in Section 6.1(c), Net Income and Net Loss for each
taxable period and all items of income, gain, loss and deduction taken into
account in computing Net Income and Net Loss for such taxable period shall be
allocated to the Unitholders, Pro Rata.

        (b)    Certain Special Allocations.    

          (i)  All Hydrocarbon Items shall be allocated to the Common
Unitholders, Pro Rata.

         (ii)  All items of deduction and loss attributable to the New Cobb
plant shall be allocated to the General Partner in its capacity as a holder of
Class A Units or any subsequent holder of such Class A Units.

        (c)    Other Special Allocations.    Notwithstanding any other provision
of this Section 6.1, the following special allocations shall be made for such
taxable period:

          (i)  Partnership Minimum Gain Chargeback.    Notwithstanding any other
provision of this Section 6.1, if there is a net decrease in Partnership Minimum
Gain during any Partnership taxable period, each Partner shall be allocated
items of Partnership income and gain for such period (and, if necessary,
subsequent periods) in the manner and amounts provided in Treasury Regulation
Sections 1.704-2(f)(6), 1.704-2(g)(2) and 1.704-2(j)(2)(i), or any successor
provision. For purposes of this Section 6.1(c)(i), each Partner's Adjusted
Capital Account balance shall be determined, and the allocation of income or
gain required hereunder shall be effected, prior to the application of any other
allocations pursuant to this Section 6.1(c)(i) with respect to such taxable
period (other than an allocation pursuant to Section 6.1(c)(v) and
Section 6.1(c)(vi)). This Section 6.1(c)(i) is intended to comply with the
Partnership Minimum Gain chargeback requirement in Treasury
Regulation Section 1.704-2(f) and shall be interpreted consistently therewith.

A-23

--------------------------------------------------------------------------------

         (ii)  Chargeback of Partner Nonrecourse Debt Minimum
Gain.    Notwithstanding the other provisions of this Section 6.1 (other than
Section 6.1(c)(i)), except as provided in Treasury Regulation
Section 1.704-2(i)(4), if there is a net decrease in Partner Nonrecourse Debt
Minimum Gain during any Partnership taxable period, any Partner with a share of
Partner Nonrecourse Debt Minimum Gain at the beginning of such taxable period
shall be allocated items of Partnership income and gain for such period (and, if
necessary, subsequent periods) in the manner and amounts provided in Treasury
Regulation Sections 1.704-2(i)(4) and 1.704-2(j)(2)(ii), or any successor
provisions. For purposes of this Section 6.1(c)(ii), each Partner's Adjusted
Capital Account balance shall be determined, and the allocation of income or
gain required hereunder shall be effected, prior to the application of any other
allocations pursuant to this Section 6.1(c)(ii), other than Section 6.1(c)(i)
and other than an allocation pursuant to Section 6.1(c)(v) and
Section 6.1(c)(vi), with respect to such taxable period. This Section 6.1(c)(ii)
is intended to comply with the chargeback of items of income and gain
requirement in Treasury Regulation Section 1.704-2(i)(4) and shall be
interpreted consistently therewith.

        (iii)    Qualified Income Offset.    In the event any Partner
unexpectedly receives any adjustments, allocations or distributions described in
Treasury Regulation Section 1.704-1(b)(2)(ii)(d)(4), 1.704-1(b)(2)(ii)(d)(5), or
1.704-1(b)(2)(ii)(d)(6), items of Partnership income and gain shall be specially
allocated to such Partner in an amount and manner sufficient to eliminate, to
the extent required by the Treasury Regulations promulgated under Section 704(b)
of the Code, the deficit balance, if any, in its Adjusted Capital Account
created by such adjustments, allocations or distributions as quickly as possible
unless such deficit balance is otherwise eliminated pursuant to
Section 6.1(c)(i) or 6.1(c)(ii).

        (iv)    Gross Income Allocations.    In the event any Partner has a
deficit balance in its Capital Account at the end of any Partnership taxable
period in excess of the sum of (A) the amount such Partner is required to
restore pursuant to the provisions of this Agreement and (B) the amount such
Partner is deemed obligated to restore pursuant to Treasury Regulation Sections
1.704-2(g) and 1.704-2(i)(5), such Partner shall be specially allocated items of
Partnership gross income and gain in the amount of such excess as quickly as
possible; provided, however, that an allocation pursuant to this
Section 6.1(c)(iv) shall be made only if and to the extent that such Partner
would have a deficit balance in its Capital Account as adjusted after all other
allocations provided for in this Section 6.1 have been tentatively made as if
this Section 6.1(c)(iv) were not in this Agreement.

        (v)    Nonrecourse Deductions.    Nonrecourse Deductions for any taxable
period shall be allocated to the Partners in accordance with their respective
Percentage Interests. If the General Partner determines in its good faith
discretion that the Partnership's Nonrecourse Deductions must be allocated in a
different ratio to satisfy the safe harbor requirements of the Treasury
Regulations promulgated under Section 704(b) of the Code, the General Partner is
authorized, upon notice to the other Partners, to revise the prescribed ratio to
the numerically closest ratio that does satisfy such requirements.

        (vi)    Partner Nonrecourse Deductions.    Partner Nonrecourse
Deductions for any taxable period shall be allocated 100% to the Partner that
bears the Economic Risk of Loss with respect to the Partner Nonrecourse Debt to
which such Partner Nonrecourse Deductions are attributable in accordance with
Treasury Regulation Section 1.704-2(i). If more than one Partner bears the
Economic Risk of Loss with respect to a Partner Nonrecourse Debt, such Partner
Nonrecourse Deductions attributable thereto shall be allocated between or among
such Partners in accordance with the ratios in which they share such Economic
Risk of Loss.

        (vii)    Nonrecourse Liabilities.    For purposes of Treasury Regulation
Section 1.752-3(a)(3), the Partners agree that Nonrecourse Liabilities of the
Partnership in excess of the sum of (A) the

A-24

--------------------------------------------------------------------------------

amount of Partnership Minimum Gain and (B) the total amount of Nonrecourse
Built-in Gain shall be allocated among the Partners in accordance with their
respective Percentage Interests.

        (viii)    Code Section 754 Adjustments.    To the extent an adjustment
to the adjusted tax basis of any Partnership asset pursuant to Section 734(b) or
743(c) of the Code is required, pursuant to Treasury Regulation
Section 1.704-1(b)(2)(iv)(m), to be taken into account in determining Capital
Accounts, the amount of such adjustment to the Capital Accounts shall be treated
as an item of gain (if the adjustment increases the basis of the asset) or loss
(if the adjustment decreases such basis), and such item of gain or loss shall be
specially allocated to the Partners in a manner consistent with the manner in
which their Capital Accounts are required to be adjusted pursuant to such
Section of the Treasury Regulations.

        (ix)    Curative Allocation.    

        (A)  Notwithstanding any other provision of this Section 6.1, other than
the Required Allocations, the Required Allocations shall be taken into account
in making the Agreed Allocations so that, to the extent possible, the net amount
of items of income, gain, loss and deduction allocated to each Partner pursuant
to the Required Allocations and the Agreed Allocations, together, shall be equal
to the net amount of such items that would have been allocated to each such
Partner under the Agreed Allocations had the Required Allocations and the
related Curative Allocation not otherwise been provided in this Section 6.1.
Notwithstanding the preceding sentence, Required Allocations relating to
(1) Nonrecourse Deductions shall not be taken into account except to the extent
that there has been a decrease in Partnership Minimum Gain and (2) Partner
Nonrecourse Deductions shall not be taken into account except to the extent that
there has been a decrease in Partner Nonrecourse Debt Minimum Gain. Allocations
pursuant to this Section 6.1(c)(ix)(A) shall only be made with respect to
Required Allocations to the extent the General Partner reasonably determines
that such allocations will otherwise be inconsistent with the economic agreement
among the Partners. Further, allocations pursuant to this Section 6.1(c)(ix)(A)
shall be deferred with respect to allocations pursuant to clauses (1) and
(2) hereof to the extent the General Partner reasonably determines that such
allocations are likely to be offset by subsequent Required Allocations.

        (B)  The General Partner shall have reasonable discretion, with respect
to each taxable period, to (1) apply the provisions of Section 6.1(c)(ix)(A) in
whatever order is most likely to minimize the economic distortions that might
otherwise result from the Required Allocations, and (2) divide all allocations
pursuant to Section 6.1(c)(ix)(A) among the Partners in a manner that is likely
to minimize such economic distortions.

         (x)  Items of income and gain allocated under the foregoing provision
of Section 6.1(c)(i), 6.1(c)(ii), 6.1(c)(iii) or 6.1(c)(viii) that are
Hydrocarbon Items shall, to the maximum extent possible, be allocated to the
Common Unitholders, Pro Rata.

        Section 6.2    Allocations for Tax Purposes.    

        (a)   Except as otherwise provided herein, for federal income tax
purposes, each item of income, gain, loss and deduction shall be allocated among
the Partners in the same manner as its correlative item of "book" income, gain,
loss or deduction is allocated pursuant to Section 6.1.

        (b)   In an attempt to eliminate Book-Tax Disparities attributable to a
Contributed Property or Adjusted Property, items of income, gain, loss,
depreciation, amortization and cost recovery deductions shall be allocated for
federal income tax purposes among the Partners as follows:

          (i)  In the case of a Contributed Property, such items attributable
thereto (A) shall be allocated among the Partners in the manner provided under
Section 704(c) of the Code that takes

A-25

--------------------------------------------------------------------------------

into account the variation between the Agreed Value of such property and its
adjusted basis at the time of contribution; and (B) any item of Residual Gain or
Residual Loss attributable to a Contributed Property shall be allocated among
the Partners in the same manner as its correlative item of "book" gain or loss
is allocated pursuant to Section 6.1.

         (ii)  In the case of an Adjusted Property, such items shall (A) first,
be allocated among the Partners in a manner consistent with the principles of
Section 704(c) of the Code to take into account the Unrealized Gain or
Unrealized Loss attributable to such property and the allocations thereof
pursuant to Section 5.3(d)(i) or 5.3(d)(ii), (B) second, in the event such
property was originally a Contributed Property, be allocated among the Partners
in a manner consistent with Section 6.2(b)(i)(A) and (C) third, any item of
Residual Gain or Residual Loss attributable to an Adjusted Property shall be
allocated among the Partners in the same manner as its correlative item of
"book" gain or loss is allocated pursuant to Section 6.1.

        (iii)  The General Partner shall apply the principles of Treasury
Regulation Section 1.704-3(d) to eliminate Book-Tax Disparities.

        (c)   For the proper administration of the Partnership and for the
preservation of uniformity of the Limited Partner Interests (or any class or
classes thereof), the General Partner shall have sole discretion to (i) adopt
such conventions as it deems appropriate in determining the amount of
depreciation, amortization and cost recovery deductions; (ii) make special
allocations for federal income tax purposes of income (including, without
limitation, gross income) or deductions; and (iii) amend the provisions of this
Agreement as appropriate (x) to reflect the proposal or promulgation of Treasury
Regulations under Section 704(b) or Section 704(c) of the Code or (y) otherwise
to preserve or achieve uniformity of the Limited Partner Interests (or any class
or classes thereof). The General Partner may adopt such conventions, make such
allocations and make such amendments to this Agreement as provided in this
Section 6.2(c) only if such conventions, allocations or amendments would not
have a material adverse effect on the Partners, the holders of any class or
classes of Limited Partner Interests issued and Outstanding or the Partnership,
and if such allocations are consistent with the principles of Section 704 of the
Code.

        (d)   The General Partner in its discretion may determine to depreciate
or amortize the portion of an adjustment under Section 743(b) of the Code
attributable to unrealized appreciation in any Adjusted Property (to the extent
of the unamortized Book-Tax Disparity) using a predetermined rate derived from
the depreciation or amortization method and useful life applied to the
Partnership's common basis of such property, despite any inconsistency of such
approach with Treasury Regulation Section 1.167(c)-l(a)(6) or any successor
regulations thereto. If the General Partner determines that such reporting
position cannot reasonably be taken, the General Partner may adopt depreciation
and amortization conventions under which all purchasers acquiring Limited
Partner Interests in the same month would receive depreciation and amortization
deductions, based upon the same applicable rate as if they had purchased a
direct interest in the Partnership's property. If the General Partner chooses
not to utilize such aggregate method, the General Partner may use any other
reasonable depreciation and amortization conventions to preserve the uniformity
of the intrinsic tax characteristics of any Limited Partner Interests that would
not have a material adverse effect on the Limited Partners or the Record Holders
of any class or classes of Limited Partner Interests.

        (e)   Any gain allocated to the Partners upon the sale or other taxable
disposition of any Partnership asset shall, to the extent possible, after taking
into account other required allocations of gain pursuant to this Section 6.2, be
characterized as Recapture Income in the same proportions and to the same extent
as such Partners (or their predecessors in interest) have been allocated any
deductions directly or indirectly giving rise to the treatment of such gains as
Recapture Income.

        (f)    All items of income, gain, loss, deduction and credit recognized
by the Partnership for federal income tax purposes and allocated to the Partners
in accordance with the provisions hereof shall be

A-26

--------------------------------------------------------------------------------

determined without regard to any election under Section 754 of the Code which
may be made by the Partnership; provided, however, that such allocations, once
made, shall be adjusted as necessary or appropriate to take into account those
adjustments permitted or required by Sections 734 and 743 of the Code.

        (g)   Each item of Partnership income, gain, loss and deduction shall
for federal income tax purposes, be determined on an annual basis and prorated
on a monthly basis and shall be allocated to the Partners as of the opening of
the New York Stock Exchange on the first Business Day of each month; provided,
however, that gain or loss on a sale or other disposition of any assets of the
Partnership or any other extraordinary item of income or loss realized and
recognized other than in the ordinary course of business, as determined by the
General Partner in its sole discretion, shall be allocated to the Partners as of
the opening of the New York Stock Exchange on the first Business Day of the
month in which such gain or loss is recognized for federal income tax purposes.
The General Partner may revise, alter or otherwise modify such methods of
allocation as it determines necessary or appropriate in its sole discretion, to
the extent permitted or required by Section 706 of the Code and the regulations
or rulings promulgated thereunder.

        (h)   Allocations that would otherwise be made to a Limited Partner
under the provisions of this Article VI shall instead be made to the beneficial
owner of Limited Partner Interests held by a nominee in any case in which the
nominee has furnished the identity of such owner to the Partnership in
accordance with Section 6031(c) of the Code or any other method acceptable to
the General Partner in its sole discretion.

        Section 6.3    Distributions.    

        (a)   Subject to Section 6.3(f), within 45 days following the end of
each Quarter, an amount equal to 100% of Available Cash with respect to such
Quarter shall, subject to Section 17-607 of the Delaware Act, be distributed in
accordance with this Article VI by the Partnership to the Unitholders, Pro Rata,
as of the Record Date selected by the General Partner in its reasonable
discretion.

        (b)   Notwithstanding Section 6.3(a), in the event of the dissolution
and liquidation of the Partnership, all receipts received during or after the
Quarter in which the Liquidation Date occurs, other than from borrowings
described in (a)(ii) of the definition of Available Cash, shall be applied and
distributed solely in accordance with, and subject to the terms and conditions
of, Section 12.3.

        (c)   In the event of the dissolution and liquidation of the
Partnership, all receipts received during or after the Quarter in which the
Liquidation Date occurs shall be applied and distributed solely in accordance
with, and subject to the terms and conditions of, Section 12.3.

        (d)   The General Partner shall have the discretion to treat taxes paid
by the Partnership on behalf of, or amounts withheld with respect to, all or
less than all of the Partners as if they had been distributed to the Partner on
whose behalf the taxes were paid or withheld.

        (e)   Each distribution in respect of a Partnership Interest shall be
paid by the Partnership, directly or through the Transfer Agent or through any
other Person or agent, only to the Record Holder of such Partnership Interest as
of the Record Date set for such distribution. Such payment shall constitute full
payment and satisfaction of the Partnership's liability in respect of such
payment, regardless of any claim of any Person who may have an interest in such
payment by reason of an assignment or otherwise.

        (f)    All Hydrocarbon Available Cash shall be distributed to the Common
Unitholders, Pro Rata.

        (g)   All other distributions of cash and other property shall be made
to all Unitholders (Common Unitholders and Class A Unitholders), Pro Rata.

A-27

--------------------------------------------------------------------------------

ARTICLE VII
MANAGEMENT AND OPERATION OF BUSINESS

        Section 7.1    Corporate Governance.    The corporate governance of the
Partnership, the General Partner or the Board of Directors shall be governed by
all applicable rules, regulations, guidelines or requirements of the National
Securities Exchange on which such Partnership Interests are listed for trading
without regard to any exemptions provided to limited partnerships under such
National Securities Exchange.

        Section 7.2    Management.    

        (a)   The General Partner shall conduct, direct and manage all
activities of the Partnership. Except as otherwise expressly provided in this
Agreement, all management powers over the business and affairs of the
Partnership shall be exclusively vested in the General Partner, and no Limited
Partner or Assignee shall have any management power over the business and
affairs of the Partnership. In addition to the powers now or hereafter granted a
general partner of a limited partnership under applicable law or which are
granted to the General Partner under any other provision of this Agreement, the
General Partner, subject to Section 7.4, shall have full power and authority to
do all things and on such terms as it, in its sole discretion, may deem
necessary or appropriate to conduct the business of the Partnership, to exercise
all powers set forth in Section 2.5 and to effectuate the purposes set forth in
Section 2.4, including the following:

          (i)  the making of any expenditures, the lending or borrowing of
money, the assumption or guarantee of, or other contracting for, indebtedness
and other liabilities, the issuance of evidences of indebtedness, including
indebtedness that is convertible into Partnership Securities, and the incurring
of any other obligations;

         (ii)  the making of tax, regulatory and other filings, or rendering of
periodic or other reports to governmental or other agencies having jurisdiction
over the business or assets of the Partnership;

        (iii)  the acquisition, disposition, mortgage, pledge, encumbrance,
hypothecation or exchange of any or all of the assets of the Partnership or the
merger or other combination of the Partnership with or into another Person (the
matters described in this clause (iii) being subject, however, to any prior
approval that may be required by Section 7.4);

        (iv)  the use of the assets of the Partnership (including cash on hand)
for any purpose consistent with the terms of this Agreement, including the
financing of the conduct of the operations of the Partnership Group; subject to
Section 7.7(a), the lending of funds to other Persons (including other Group
Members); the repayment or guarantee of obligations of the Partnership Group;
and the making of capital contributions to any member of the Partnership Group;

         (v)  the negotiation, execution and performance of any contracts,
conveyances or other instruments (including instruments that limit the liability
of the Partnership under contractual arrangements to all or particular assets of
the Partnership, with the other party to the contract to have no recourse
against the General Partner or its assets other than its interest in the
Partnership, even if same results in the terms of the transaction being less
favorable to the Partnership than would otherwise be the case);

        (vi)  the distribution of Partnership cash;

       (vii)  the selection and dismissal of employees (including employees
having titles such as "president," "vice president," "secretary" and
"treasurer") and agents, outside attorneys, accountants, consultants and
contractors and the determination of their compensation and other terms of
employment or hiring;

A-28

--------------------------------------------------------------------------------

      (viii)  the maintenance of such insurance for the benefit of the
Partnership Group and the Partners as it deems necessary or appropriate;

        (ix)  the formation of, or acquisition of an interest in, and the
contribution of property and the making of loans to, any further limited or
general partnerships, joint ventures, corporations, limited liability companies
or other relationships (including the acquisition of interests in, and the
contributions of property to, any Group Member from time to time) subject to the
restrictions set forth in Section 2.4;

         (x)  the control of any matters affecting the rights and obligations of
the Partnership, including the bringing and defending of actions at law or in
equity and otherwise engaging in the conduct of litigation and the incurring of
legal expense and the settlement of claims and litigation;

        (xi)  the indemnification of any Person against liabilities and
contingencies to the extent permitted by law;

       (xii)  the entering into of listing agreements with any National
Securities Exchange and the delisting of some or all of the Limited Partner
Interests from, or requesting that trading be suspended on, any such exchange
(subject to any prior approval that may be required under Section 4.6);

      (xiii)  the purchase, sale or other acquisition or disposition of
Partnership Securities, or the issuance of additional options, rights, warrants
and appreciation rights relating to Partnership Securities; and

      (xiv)  the undertaking of any action in connection with the Partnership's
participation in any Group Member as a member or partner.

        Section 7.3    Certificate of Limited Partnership.    The General
Partner has caused the Certificate of Limited Partnership to be filed with the
Secretary of State of the State of Delaware as required by the Delaware Act. The
General Partner shall use all reasonable efforts to cause to be filed such other
certificates or documents as may be determined by the General Partner in its
sole discretion to be reasonable and necessary or appropriate for the formation,
continuation, qualification and operation of a limited partnership (or a
partnership in which the limited partners have limited liability) in the State
of Delaware or any other state in which the Partnership may elect to do business
or own property. To the extent that such action is determined by the General
Partner in its sole discretion to be reasonable and necessary or appropriate,
the General Partner shall file amendments to and restatements of the Certificate
of Limited Partnership and do all things necessary to maintain the Partnership
as a limited partnership (or a partnership or other entity in which the limited
partners have limited liability) under the laws of the State of Delaware or of
any other state in which the Partnership may elect to do business or own
property. Subject to the terms of Section 3.4(a), the General Partner shall not
be required, before or after filing, to deliver or mail a copy of the
Certificate of Limited Partnership, any qualification document or any amendment
thereto to any Limited Partner.

        Section 7.4    Restrictions on the General Partner's Authority.    

        (a)   The General Partner may not, without written approval of the
specific act by holders of all of the Outstanding Limited Partner Interests or
by other written instrument executed and delivered by holders of all of the
Outstanding Limited Partner Interests subsequent to the date of this Agreement,
take any action in contravention of this Agreement, including, except as
otherwise provided in this Agreement, (i) committing any act that would make it
impossible to carry on the ordinary business of the Partnership; (ii) possessing
Partnership property, or assigning any rights in specific Partnership property,
for other than a Partnership purpose; (iii) admitting a Person as a Partner; or
(iv) amending this Agreement in any manner.

A-29

--------------------------------------------------------------------------------

        (b)   Except as provided in Articles XII and XIV, the General Partner
may not sell, exchange or otherwise dispose of all or substantially all of the
Partnership's assets in a single transaction or a series of related transactions
(including by way of merger, consolidation or other combination) or approve on
behalf of the Partnership the sale, exchange or other disposition of all or
substantially all of the assets of the Operating Company and its subsidiaries
taken as a whole without the approval of holders of a majority of the
Outstanding Voting Units; provided, however, that this provision shall not
preclude or limit the General Partner's ability to mortgage, pledge, hypothecate
or grant a security interest in all or substantially all of the assets of the
Partnership or the Operating Company and shall not apply to any forced sale of
any or all of the assets of the Partnership or the Operating Company pursuant to
the foreclosure of, or other realization upon, any such encumbrance. Without the
approval of holders of a majority of the Outstanding Voting Units, the General
Partner shall not, on behalf of the Partnership, consent to any amendment to the
Operating Company Agreement or take any action permitted to be taken by a member
of the Operating Company, in either case, that would adversely affect the
Limited Partners (including any particular class of Partnership Interests as
compared to any other class of Partnership Interests) in any material respect.

        Section 7.5    Reimbursement of the General Partner.    

        (a)   Except as provided in this Section 7.5 and elsewhere in this
Agreement, the General Partner shall not be compensated for its services as a
general partner or managing member of any Group Member.

        (b)   The General Partner shall be reimbursed on a monthly basis, or
such other reasonable basis as the General Partner may determine in its sole
discretion, for (i) all direct and indirect expenses it incurs or payments it
makes on behalf of the Partnership (including salary, bonus, incentive
compensation and other amounts paid to any Person including Affiliates of the
General Partner to perform services for the Partnership or for the General
Partner in the discharge of its duties to the Partnership), and (ii) all other
necessary or appropriate expenses allocable to the Partnership or otherwise
reasonably incurred by the General Partner in connection with operating the
Partnership's business (including expenses allocated to the General Partner by
its Affiliates). The General Partner shall determine the expenses that are
allocable to the Partnership in any reasonable manner determined by the General
Partner in its sole discretion. Reimbursements pursuant to this Section 7.5
shall be in addition to any reimbursement to the General Partner as a result of
indemnification pursuant to Section 7.8.

        (c)   The General Partner, in its sole discretion and without the
approval of the Limited Partners (who shall have no right to vote in respect
thereof), may propose and adopt on behalf of the Partnership employee benefit
plans, employee programs and employee practices (including plans, programs and
practices involving the issuance of Partnership Securities or options to
purchase or rights, warrants or appreciation rights relating to Partnership
Securities), or cause the Partnership to issue Partnership Securities in
connection with, or pursuant to, any employee benefit plan, employee program or
employee practice maintained or sponsored by the General Partner or any of its
Affiliates, in each case for the benefit of employees of the General Partner,
any Group Member or any Affiliate, or any of them, in respect of services
performed, directly or indirectly, for the benefit of the Partnership Group. The
Partnership agrees to issue to the employees any Partnership Securities that the
General Partner is obligated to provide to such employees pursuant to any such
employee benefit plans, employee programs or employee practices. Expenses
incurred by the General Partner in connection with any such plans, programs and
practices (including the net cost to the General Partner or such Affiliates of
Partnership Securities purchased by the General Partner or such Affiliates from
the Partnership to fulfill options or awards under such plans, programs and
practices) shall be reimbursed in accordance with Section 7.5(b). Any and all
obligations of the General Partner under any employee benefit plans, employee
programs or employee practices adopted by the General Partner as permitted by
this Section 7.5(c) shall constitute obligations of the General Partner
hereunder.

A-30

--------------------------------------------------------------------------------

        Section 7.6    Outside Activities.    

        (a)   The General Partner (i) agrees that its sole business will be to
act as a general partner or managing member, as the case may be, of the
Partnership and any other partnership or limited liability company of which the
Partnership or the Operating Company is, directly or indirectly, a partner or
member and to undertake activities that are ancillary or related thereto
(including being a limited partner in the Partnership), and (ii) shall not
engage in any business or activity or incur any debts or liabilities except in
connection with or incidental to (A) its performance as general partner or
managing member of one or more Group Members, or (B) the acquiring, owning or
disposing of debt or equity securities in any Group Member.

        (b)   The General Partner may acquire only the Partnership Interests.

        (c)   Anything in this Agreement to the contrary notwithstanding, to the
extent that provisions of Section 7.8, 7.9, 7.10 or other Sections of this
Agreement purport or are interpreted to have the effect of restricting the
fiduciary duties that might otherwise, as a result of Delaware or other
applicable law, be owed by the General Partner to the Partnership and its
Limited Partners, or to constitute a waiver or consent by the Limited Partners
to any such restriction, such provisions shall be inapplicable and have no
effect in determining whether the General Partner has complied with its
fiduciary duties in connection with determinations made by it under this
Section 7.6.

        Section 7.7    Loans from the General Partner; Loans or Contributions
from the Partnership; Contracts with Affiliates; Certain Restrictions on the
General Partner.    

        (a)   The General Partner or any of its Affiliates may lend to any Group
Member, and any Group Member may borrow from the General Partner or any of its
Affiliates, funds needed or desired by the Group Member for such periods of time
and in such amounts as the General Partner may determine; provided, however,
that in any such case the lending party may not charge the borrowing party
interest at a rate greater than the rate that would be charged the borrowing
party or impose terms less favorable to the borrowing party than would be
charged or imposed on the borrowing party by unrelated lenders on comparable
loans made on an arm's-length basis (without reference to the lending party's
financial abilities or guarantees). The borrowing party shall reimburse the
lending party for any costs (other than any additional interest costs) incurred
by the lending party in connection with the borrowing of such funds. For
purposes of this Section 7.7(a) and Section 7.7(b), the term "Group Member"
shall include any Affiliate of a Group Member that is controlled by the Group
Member. No Group Member may lend funds to the General Partner or any of its
Affiliates (other than another Group Member).

        (b)   The Partnership may lend or contribute to any Group Member, and
any Group Member may borrow from the Partnership, funds on terms and conditions
established in the sole discretion of the General Partner; provided, however,
that the Partnership may not charge the Group Member interest at a rate less
than the rate that would be charged to the Group Member (without reference to
the General Partner's financial abilities or guarantees) by unrelated lenders on
comparable loans. The foregoing authority shall be exercised by the General
Partner in its sole discretion and shall not create any right or benefit in
favor of any Group Member or any other Person.

        (c)   The General Partner may itself, or may enter into an agreement
with any of its Affiliates to, render services to a Group Member or to the
General Partner in the discharge of its duties as General Partner of the
Partnership. Any services rendered to a Group Member by the General Partner or
any of its Affiliates shall be on terms that are fair and reasonable to the
Partnership; provided, however, that the requirements of this Section 7.7(c)
shall be deemed satisfied as to (i) any transaction approved by the Board of
Directors, (ii) any transaction, the terms of which are no less favorable to the
Partnership Group than those generally being provided to or available from
unrelated third parties or (iii) any transaction that, taking into account the
totality of the relationships between the parties involved

A-31

--------------------------------------------------------------------------------

(including other transactions that may be particularly favorable or advantageous
to the Partnership Group), is equitable to the Partnership Group. The provisions
of Section 7.5 shall apply to the rendering of services described in this
Section 7.7(c).

        (d)   The Partnership Group may transfer assets to joint ventures, other
partnerships, corporations, limited liability companies or other business
entities in which it is or thereby becomes a participant upon such terms and
subject to such conditions as are consistent with this Agreement and applicable
law.

        (e)   Neither the General Partner nor any of its Affiliates shall sell,
transfer or convey any property to, or purchase any property from, the
Partnership, directly or indirectly, except pursuant to transactions that are
fair and reasonable to the Partnership; provided, however, that the requirements
of this Section 7.7(e) shall be deemed to be satisfied as to (i) any transaction
approved by the Board of Directors, (ii) any transaction, the terms of which are
no less favorable to the Partnership than those generally being provided to or
available from unrelated third parties, or (iii) any transaction that, taking
into account the totality of the relationships between the parties involved
(including other transactions that may be particularly favorable or advantageous
to the Partnership), is equitable to the Partnership. With respect to any
contribution of assets to the Partnership in exchange for Partnership
Securities, the Board of Directors, in determining whether the appropriate
number of Partnership Securities are being issued, may take into account, among
other things, the fair market value of the assets, the liquidated and contingent
liabilities assumed, the tax basis in the assets, the extent to which tax-only
allocations to the transferor will protect the existing partners of the
Partnership against a low tax basis, and such other factors as the Board of
Directors deems relevant under the circumstances.

        (f)    The General Partner and its Affiliates will have no obligation to
permit any Group Member to use any facilities or assets of the General Partner
and its Affiliates, except as may be provided in contracts entered into from
time to time specifically dealing with such use, nor shall there be any
obligation on the part of the General Partner or its Affiliates to enter into
such contracts.

        Section 7.8    Indemnification.    

        (a)   To the fullest extent permitted by law but subject to the
limitations expressly provided in this Agreement, all Indemnitees shall be
indemnified and held harmless by the Partnership from and against any and all
losses, claims, damages, liabilities, joint or several, expenses (including
legal fees and expenses), judgments, fines, penalties, interest, settlements or
other amounts arising from any and all claims, demands, actions, suits or
proceedings, whether civil, criminal, administrative or investigative, in which
any Indemnitee may be involved, or is threatened to be involved, as a party or
otherwise, by reason of its status as an Indemnitee; provided, however, that the
Indemnitee shall not be indemnified and held harmless if there has been a final
and non-appealable judgment entered by a court of competent jurisdiction
determining that, in respect of the matter for which the Indemnitee is seeking
indemnification pursuant to this Section 7.8, the Indemnitee acted in bad faith
or engaged in fraud, willful misconduct or, in the case of a criminal matter,
acted with knowledge that the Indemnitee's conduct was unlawful; provided,
further, no indemnification pursuant to this Section 7.8 shall be available to
the General Partner or its Affiliates (other than a Group Member) with respect
to its or their obligations incurred pursuant to the Contribution Agreement
(other than obligations incurred by the General Partner on behalf of the
Partnership). Any indemnification pursuant to this Section 7.8 shall be made
only out of the assets of the Partnership, it being agreed that the General
Partner shall not be personally liable for such indemnification and shall have
no obligation to contribute or loan any monies or property to the Partnership to
enable it to effectuate such indemnification.

        (b)   To the fullest extent permitted by law, expenses (including legal
fees and expenses) incurred by an Indemnitee who is indemnified pursuant to
Section 7.8(a) in defending any claim, demand, action, suit or proceeding shall,
from time to time, be advanced by the Partnership prior to a determination that
the Indemnitee is not entitled to be indemnified upon receipt by the Partnership
of

A-32

--------------------------------------------------------------------------------

an agreement by or on behalf of the Indemnitee to repay such amount if it shall
be determined that the Indemnitee is not entitled to be indemnified as
authorized in this Section 7.8.

        (c)   The indemnification provided by this Section 7.8 shall be in
addition to any other rights to which an Indemnitee may be entitled under any
agreement, pursuant to any vote of the holders of Outstanding Limited Partner
Interests, as a matter of law or otherwise, both as to actions in the
Indemnitee's capacity as an Indemnitee and as to actions in any other capacity,
and shall continue as to an Indemnitee who has ceased to serve in such capacity
and shall inure to the benefit of the heirs, successors, assigns and
administrators of the Indemnitee.

        (d)   The Partnership may purchase and maintain (or reimburse the
General Partner or its Affiliates for the cost of) insurance, on behalf of the
General Partner, its Affiliates and such other Persons as the General Partner
shall determine, against any liability that may be asserted against or expense
that may be incurred by such Person in connection with the Partnership's
activities or such Person's activities on behalf of the Partnership, regardless
of whether the Partnership would have the power to indemnify such Person against
such liability under the provisions of this Agreement.

        (e)   For purposes of this Section 7.8, the Partnership shall be deemed
to have requested an Indemnitee to serve as fiduciary of an employee benefit
plan whenever the performance by it of its duties to the Partnership also
imposes duties on, or otherwise involves services by, it to the plan or
participants or beneficiaries of the plan; excise taxes assessed on an
Indemnitee with respect to an employee benefit plan pursuant to applicable law
shall constitute "fines" within the meaning of Section 7.8(a); and action taken
or omitted by it with respect to any employee benefit plan in the performance of
its duties for a purpose reasonably believed by it to be in the best interest of
the participants and beneficiaries of the plan shall be deemed to be for a
purpose that is in the best interests of the Partnership.

        (f)    In no event may an Indemnitee subject the Limited Partners to
personal liability by reason of the indemnification provisions set forth in this
Agreement.

        (g)   An Indemnitee shall not be denied indemnification in whole or in
part under this Section 7.8 because the Indemnitee had an interest in the
transaction with respect to which the indemnification applies if the transaction
was otherwise permitted by the terms of this Agreement or any predecessor
agreement thereto, including a transaction involving the General Partner, any
Affiliate thereof and/or any member, partner, officer, director, employee, agent
or trustee of any Group Member, the General Partner or any Affiliate of any
Group Member.

        (h)   The provisions of this Section 7.8 are for the benefit of the
Indemnitees, their heirs, successors, assigns and administrators and shall not
be deemed to create any rights for the benefit of any other Persons.

        (i)    No amendment, modification or repeal of this Section 7.8 or any
provision hereof shall in any manner terminate, reduce or impair the right of
any past, present or future Indemnitee to be indemnified by the Partnership, nor
the obligations of the Partnership to indemnify any such Indemnitee under and in
accordance with the provisions of this Section 7.8 as in effect immediately
prior to such amendment, modification or repeal with respect to claims arising
from or relating to matters occurring, in whole or in part, prior to such
amendment, modification or repeal, regardless of when such claims may arise or
be asserted.

        Section 7.9    Liability of Indemnitees.    

        (a)   Notwithstanding anything to the contrary set forth in this
Agreement, no Indemnitee shall be liable for monetary damages to the
Partnership, the Limited Partners, the Assignees or any other Persons who have
acquired interests in the Partnership Securities, for losses sustained or
liabilities incurred as a result of any act or omission if such Indemnitee acted
in good faith.

A-33

--------------------------------------------------------------------------------

        (b)   Subject to its obligations and duties as General Partner set forth
in Section 7.2(a), the General Partner may exercise any of the powers granted to
it by this Agreement and perform any of the duties imposed upon it hereunder
either directly or by or through its agents, and the General Partner shall not
be responsible for any misconduct or negligence on the part of any such agent
appointed by the General Partner in good faith.

        (c)   To the extent that, at law or in equity, an Indemnitee has duties
(including fiduciary duties) and liabilities relating thereto to the Partnership
or to the Partners, the General Partner and any other Indemnitee acting in
connection with the Partnership's business or affairs shall not be liable to the
Partnership or to any Partner for its good faith reliance on the provisions of
this Agreement. The provisions of this Agreement, to the extent that they
restrict or otherwise modify the duties and liabilities of an Indemnitee
otherwise existing at law or in equity, are agreed by the Partners to replace
such other duties and liabilities of such Indemnitee.

        (d)   Any amendment, modification or repeal of this Section 7.9 or any
provision hereof shall be prospective only and shall not in any way affect the
limitations on the liability to the Partnership, the Limited Partners, the
General Partner, and the Partnership's and General Partner's directors, officers
and employees under this Section 7.9 as in effect immediately prior to such
amendment, modification or repeal with respect to claims arising from or
relating to matters occurring, in whole or in part, prior to such amendment,
modification or repeal, regardless of when such claims may arise or be asserted.

        Section 7.10    Other Matters Concerning the General Partner.    

        (a)   The General Partner may rely and shall be protected in acting or
refraining from acting upon any resolution, certificate, statement, instrument,
opinion, report, notice, request, consent, order, bond, debenture or other paper
or document believed by it to be genuine and to have been signed or presented by
the proper party or parties.

        (b)   The General Partner may consult with legal counsel, accountants,
appraisers, management consultants, investment bankers and other consultants and
advisers selected by it, and any act taken or omitted to be taken in reliance
upon the opinion (including an Opinion of Counsel) of such Persons as to matters
that the General Partner reasonably believes to be within such Person's
professional or expert competence shall be conclusively presumed to have been
done or omitted in good faith and in accordance with such opinion.

        (c)   The General Partner shall have the right, in respect of any of its
powers or obligations hereunder, to act through any of its duly authorized
officers, a duly appointed attorney or attorneys-in-fact or the duly authorized
officers of the Partnership.

        (d)   Any standard of care and duty imposed by this Agreement or under
the Delaware Act or any applicable law, rule or regulation shall be modified,
waived or limited, to the extent permitted by law, as required to permit the
General Partner to act under this Agreement or any other agreement contemplated
by this Agreement and to make any decision pursuant to the authority prescribed
in this Agreement, so long as such action is reasonably believed by the General
Partner to be in, or not inconsistent with, the best interests of the
Partnership.

        Section 7.11    Purchase or Sale of Partnership Securities.    The
General Partner may cause the Partnership to purchase or otherwise acquire
Partnership Securities. As long as Partnership Securities are held by any Group
Member, such Partnership Securities shall not be considered Outstanding for any
purpose, except as otherwise provided herein. The General Partner or any
Affiliate of the General Partner may also purchase or otherwise acquire and sell
or otherwise dispose of Partnership Securities for its own account, subject to
the provisions of Articles IV and X.

        Section 7.12    Reliance by Third Parties.    Notwithstanding anything
to the contrary in this Agreement, any Person dealing with the Partnership shall
be entitled to assume that the General

A-34

--------------------------------------------------------------------------------

Partner and any officer of the General Partner authorized by the General Partner
to act on behalf of and in the name of the Partnership has full power and
authority to encumber, sell or otherwise use in any manner any and all assets of
the Partnership and to enter into any authorized contracts on behalf of the
Partnership, and such Person shall be entitled to deal with the General Partner
or any such officer as if it were the Partnership's sole party in interest, both
legally and beneficially. Each Limited Partner hereby waives any and all
defenses or other remedies that may be available against such Person to contest,
negate or disaffirm any action of the General Partner or any such officer in
connection with any such dealing. In no event shall any Person dealing with the
General Partner or any such officer or its representatives be obligated to
ascertain that the terms of the Agreement have been complied with or to inquire
into the necessity or expedience of any act or action of the General Partner or
any such officer or its representatives. Each and every certificate, document or
other instrument executed on behalf of the Partnership by the General Partner or
its representatives shall be conclusive evidence in favor of any and every
Person relying thereon or claiming thereunder that (a) at the time of the
execution and delivery of such certificate, document or instrument, this
Agreement was in full force and effect, (b) the Person executing and delivering
such certificate, document or instrument was duly authorized and empowered to do
so for and on behalf of the Partnership and (c) such certificate, document or
instrument was duly executed and delivered in accordance with the terms and
provisions of this Agreement and is binding upon the Partnership.

ARTICLE VIII
BOOKS, RECORDS, ACCOUNTING AND REPORTS

        Section 8.1    Records and Accounting.    The General Partner shall keep
or cause to be kept at the principal office of the Partnership appropriate books
and records with respect to the Partnership's business, including all books and
records necessary to provide to the Limited Partners any information required to
be provided pursuant to Section 3.4(a). Any books and records maintained by or
on behalf of the Partnership in the regular course of its business, including
the record of the Record Holders and Assignees of Units or other Partnership
Securities, books of account and records of Partnership proceedings, may be kept
on, or be in the form of, computer disks, hard drives, punch cards, magnetic
tape, photographs, micrographics or any other information storage device;
provided, however, that the books and records so maintained are convertible into
clearly legible written form within a reasonable period of time. The books of
the Partnership shall be maintained, for financial reporting purposes, on an
accrual basis in accordance with U.S. GAAP.

        Section 8.2    Fiscal Year.    The fiscal year of the Partnership shall
be a fiscal year ending December 31.

        Section 8.3    Reports.    

        (a)   As soon as practicable, but in no event later than 120 days after
the close of each fiscal year of the Partnership, the General Partner shall
cause to be mailed or made available to each Record Holder of a Unit as of a
date selected by the General Partner in its discretion, an annual report
containing financial statements of the Partnership for such fiscal year of the
Partnership, presented in accordance with U.S. GAAP, including a balance sheet
and statements of operations, Partnership equity and cash flows, such statements
to be audited by a firm of independent public accountants selected by the
General Partner.

        (b)   As soon as practicable, but in no event later than 90 days after
the close of each Quarter except the last Quarter of each fiscal year, the
General Partner shall cause to be mailed or made available to each Record Holder
of a Unit, as of a date selected by the General Partner in its discretion, a
report containing unaudited financial statements of the Partnership and such
other information as may be required by applicable law, regulation or rule of
any National Securities

A-35

--------------------------------------------------------------------------------

Exchange on which the Units are listed for trading, or as the General Partner
determines to be necessary or appropriate.

ARTICLE IX
TAX MATTERS

        Section 9.1    Tax Returns and Information.    The Partnership shall
timely file all returns of the Partnership that are required for federal, state
and local income tax purposes on the basis of the accrual method and a taxable
year ending on December 31. The tax information reasonably required by Record
Holders for federal and state income tax reporting purposes with respect to a
taxable year shall be furnished to them within 90 days of the close of the
calendar year in which the Partnership's taxable year ends. The classification,
realization and recognition of income, gain, losses and deductions and other
items shall be on the accrual method of accounting for federal income tax
purposes.

        Section 9.2    Tax Elections.    

        (a)   The Partnership shall make the election under Section 754 of the
Code in accordance with applicable regulations thereunder, subject to the
reservation of the right to seek to revoke any such election upon the General
Partner's determination that such revocation is in the best interests of the
Limited Partners. Notwithstanding any other provision herein contained, for the
purposes of computing the adjustments under Section 743(b) of the Code, the
General Partner shall be authorized (but not required) to adopt a convention
whereby the price paid by a transferee of a Limited Partner Interest will be
deemed to be the lowest quoted closing price of the Limited Partner Interests on
any National Securities Exchange on which such Limited Partner Interests are
traded during the calendar month in which such transfer is deemed to occur
pursuant to Section 6.2(g) without regard to the actual price paid by such
transferee.

        (b)   The Partnership shall elect to deduct expenses incurred in
organizing the Partnership ratably over a sixty-month period as provided in
Section 709 of the Code.

        (c)   Except as otherwise provided herein, the General Partner shall
determine whether the Partnership should make any other elections permitted by
the Code.

        Section 9.3    Tax Controversies.    Subject to the provisions hereof,
the General Partner is designated as the Tax Matters Partner (as defined in the
Code) and is authorized and required to represent the Partnership (at the
Partnership's expense) in connection with all examinations of the Partnership's
affairs by tax authorities, including resulting administrative and judicial
proceedings, and to expend Partnership funds for professional services and costs
associated therewith. Each Partner agrees to cooperate with the General Partner
and to do or refrain from doing any or all things reasonably required by the
General Partner to conduct such proceedings.

        Section 9.4    Withholding.    Notwithstanding any other provision of
this Agreement, the General Partner is authorized to take any action that it
determines in its discretion to be necessary or appropriate to cause the
Partnership and other Group Members to comply with any withholding requirements
established under the Code or any other federal, state or local law including,
without limitation, pursuant to Sections 1441, 1442, 1445 and 1446 of the Code.
To the extent that the Partnership is required or elects to withhold and pay
over to any taxing authority any amount resulting from the allocation or
distribution of income to any Partner or Assignee (including, without
limitation, by reason of Section 1446 of the Code), the amount withheld may at
the discretion of the General Partner be treated by the Partnership as a
distribution of cash pursuant to Section 6.3 in the amount of such withholding
from such Partner.

A-36

--------------------------------------------------------------------------------

ARTICLE X
ADMISSION OF PARTNERS

        Section 10.1    Admission of Substituted Limited Partner.    By transfer
of a Limited Partner Interest in accordance with Article IV, the transferor
shall be deemed to have given the transferee the right to seek admission as a
Substituted Limited Partner subject to the conditions of, and in the manner
permitted under, this Agreement. A transferor of a Certificate representing a
Limited Partner Interest shall, however, only have the authority to convey to a
purchaser or other transferee who does not execute and deliver a Transfer
Application (a) the right to negotiate such Certificate to a purchaser or other
transferee and (b) the right to transfer the right to request admission as a
Substituted Limited Partner to such purchaser or other transferee in respect of
the transferred Limited Partner Interests. Each transferee of a Limited Partner
Interest (including any nominee holder or an agent acquiring such Limited
Partner Interest for the account of another Person) who executes and delivers a
Transfer Application shall, by virtue of such execution and delivery, be an
Assignee and be deemed to have applied to become a Substituted Limited Partner
with respect to the Limited Partner Interests so transferred to such Person.
Such Assignee shall become a Substituted Limited Partner (x) at such time as the
General Partner consents thereto, which consent may be given or withheld in the
General Partner's discretion, and (y) when any such admission is shown on the
books and records of the Partnership. If such consent is withheld, such
transferee shall be an Assignee. An Assignee shall have an interest in the
Partnership equivalent to that of a Limited Partner with respect to allocations
and distributions, including liquidating distributions, of the Partnership. With
respect to voting rights attributable to Limited Partner Interests that are held
by Assignees, the General Partner shall be deemed to be the Limited Partner with
respect thereto and shall, in exercising the voting rights in respect of such
Limited Partner Interests on any matter, vote such Limited Partner Interests at
the written direction of the Assignee who is the Record Holder of such Limited
Partner Interests. If no such written direction is received, such Limited
Partner Interests will not be voted. An Assignee shall have no other rights of a
Limited Partner.

        Section 10.2    Admission of Additional Limited Partners.    

        (a)   A Person (other than the General Partner or a Limited Partner) who
makes a Capital Contribution to the Partnership in accordance with this
Agreement shall be admitted to the Partnership as an Additional Limited Partner
only upon furnishing to the General Partner

          (i)  evidence of acceptance in form satisfactory to the General
Partner of all of the terms and conditions of this Agreement, including the
power of attorney granted in Section 2.6, and

         (ii)  such other documents or instruments as may be required in the
discretion of the General Partner to effect such Person's admission as an
Additional Limited Partner.

        (b)   Notwithstanding anything to the contrary in this Section 10.2, no
Person shall be admitted as an Additional Limited Partner without the consent of
the General Partner, which consent may be given or withheld in the General
Partner's discretion. The admission of any Person as an Additional Limited
Partner shall become effective on the date upon which the name of such Person is
recorded as such in the books and records of the Partnership, following the
consent of the General Partner to such admission.

        Section 10.3    Amendment of Agreement and Certificate of Limited
Partnership.    To effect the admission to the Partnership of any Partner, the
General Partner shall take all steps necessary and appropriate under the
Delaware Act to amend the records of the Partnership to reflect such admission
and, if necessary, to prepare as soon as practicable an amendment to this
Agreement and, if required by law, the General Partner shall prepare and file an
amendment to the Certificate of Limited Partnership, and the General Partner may
for this purpose, among others, exercise the power of attorney granted pursuant
to Section 2.6.

A-37

--------------------------------------------------------------------------------

ARTICLE XI
WITHDRAWAL OR REMOVAL OF PARTNERS

        Section 11.1    No Withdrawal or Removal of the General Partner    

        (a)   The General Partner may not withdraw and may not be removed at any
time for any reason whatsoever. Any attempt of withdrawal or removal of the
General Partner shall be null and void.

        (b)   Notwithstanding Section 11.1(a), if the General Partner withdraws
in violation of this Agreement pursuant to Section 17-602 of the Delaware Act:

          (i)  The withdrawing General Partner shall give 90 days prior notice
of such withdrawal to the Limited Partners.

         (ii)  The successor General Partner shall be elected by a plurality of
the votes of the Unitholders cast at a special meeting or an annual meeting
where a quorum is present.

        (iii)  A successor General Partner elected pursuant to
Section 11.1(b)(ii) shall be admitted to the Partnership as the General Partner,
effective as of the date immediately prior to the withdrawal of the predecessor
General Partner; provided, however, that no such successor shall be admitted to
the Partnership until such successor has executed and delivered this Agreement
and such other documents or instruments as may be required to effect such
admission. Any such successor shall, subject to the terms hereof, carry on the
business of the members of the Partnership Group without dissolution.

        (iv)  The Person so elected as successor General Partner shall
automatically become the successor general partner or managing member, to the
extent applicable, of the other Group Members of which the General Partner is a
general partner or a managing member.

         (v)  Upon the withdrawal of the General Partner, if a successor General
Partner is elected pursuant to Section 11.1(b)(ii), the Partnership shall not be
dissolved and such successor General Partner shall continue the business of the
Partnership.

        Section 11.2    Withdrawal of Limited Partners.    No Limited Partner
shall have any right to withdraw from the Partnership; provided, however, that
when a transferee of a Limited Partner's Limited Partner Interest becomes a
Record Holder of the Limited Partner Interest so transferred, such transferring
Limited Partner shall cease to be a Limited Partner with respect to the Limited
Partner Interest so transferred.

ARTICLE XII
DISSOLUTION AND LIQUIDATION

        Section 12.1    Dissolution.    The Partnership shall not be dissolved
by the admission of Substituted Limited Partners or Additional Limited Partners
in accordance with the terms of this Agreement. The Partnership shall dissolve,
and its affairs shall be wound up, upon:

        (a)   withdrawal of the General Partner in violation of this Agreement
pursuant to Section 17-602 of the Delaware Act and the successor General Partner
is not admitted to the Partnership pursuant to Section 11.1(b);

        (b)   an election to dissolve the Partnership by the General Partner
that is approved by the holders of a majority of the Outstanding Voting Units;

        (c)   the entry of a decree of judicial dissolution of the Partnership
pursuant to the provisions of the Delaware Act; or

        (d)   the sale of all or substantially all of the assets and properties
of the Partnership Group.

A-38

--------------------------------------------------------------------------------

        Section 12.2    Liquidator.    Upon dissolution of the Partnership, the
General Partner shall select one or more Persons to act as Liquidator. The
Liquidator (if other than the General Partner) shall be entitled to receive such
compensation for its services as may be approved by holders of at least a
majority of the Outstanding Common Units. The Liquidator (if other than the
General Partner) shall agree not to resign at any time without 15 days' prior
notice and may be removed at any time, with or without cause, by notice of
removal approved by holders of at least a majority of the Outstanding Common
Units. Upon dissolution, removal or resignation of the Liquidator, a successor
and substitute Liquidator (who shall have and succeed to all rights, powers and
duties of the original Liquidator) shall within 30 days thereafter be approved
by holders of at least a majority of the Outstanding Common Units. The right to
approve a successor or substitute Liquidator in the manner provided herein shall
be deemed to refer also to any such successor or substitute Liquidator approved
in the manner herein provided. Except as expressly provided in this Article XII,
the Liquidator approved in the manner provided herein shall have and may
exercise, without further authorization or consent of any of the parties hereto,
all of the powers conferred upon the General Partner under the terms of this
Agreement (but subject to all of the applicable limitations, contractual and
otherwise, upon the exercise of such powers, other than the limitation on sale
set forth in Section 7.4(b)) to the extent necessary or desirable in the good
faith judgment of the Liquidator to carry out the duties and functions of the
Liquidator hereunder for and during such period of time as shall be reasonably
required in the good faith judgment of the Liquidator to complete the winding up
and liquidation of the Partnership as provided for herein.

        Section 12.3    Liquidation.    The Liquidator shall proceed to dispose
of the assets of the Partnership, discharge its liabilities, and otherwise wind
up its affairs in such manner and over such period as the Liquidator determines
to be in the best interest of the Partners, subject to Section 17-804 of the
Delaware Act and the following:

        (a)   The assets may be disposed of by public or private sale or by
distribution in kind to one or more Partners on such terms as the Liquidator and
such Partner or Partners may agree. If any property is distributed in kind, the
Partner receiving the property shall be deemed for purposes of Section 12.3(c)
to have received cash equal to its fair market value; and contemporaneously
therewith, appropriate cash distributions must be made to the other Partners.
The Liquidator may, in its absolute discretion, defer liquidation or
distribution of the Partnership's assets for a reasonable time if it determines
that an immediate sale or distribution of all or some of the Partnership's
assets would be impractical or would cause undue loss to the Partners. The
Liquidator may, in its absolute discretion, distribute the Partnership's assets,
in whole or in part, in kind if it determines that a sale would be impractical
or would cause undue loss to the Partners.

        (b)   Liabilities of the Partnership include amounts owed to the
Liquidator as compensation for serving in such capacity (subject to the terms of
Section 12.2) and amounts to Partners otherwise than in respect of their
distribution rights under Article VI. With respect to any liability that is
contingent, conditional or unmatured or is otherwise not yet due and payable,
the Liquidator shall either settle such claim for such amount as it thinks
appropriate or establish a reserve of cash or other assets to provide for its
payment. When paid, any unused portion of the reserve shall be distributed as
additional liquidation proceeds.

        (c)   All property and all cash in excess of that required to discharge
liabilities as provided in Section 12.3(b) shall be distributed to the Partners
in accordance with, and to the extent of, the positive balances in their
respective Capital Accounts, as determined after taking into account all Capital
Account adjustments (other than those made by reason of distributions pursuant
to this Section 12.3(c)) for the taxable year of the Partnership during which
the liquidation of the Partnership occurs (with such date of occurrence being
determined pursuant to Treasury Regulation Section 1.704-1(b)(2)(ii)(g)), and
such distribution shall be made by the end of such taxable year (or, if later,
within 90 days after said date of such occurrence).

A-39

--------------------------------------------------------------------------------

        Section 12.4    Cancellation of Certificate of Limited
Partnership.    Upon the completion of the distribution of Partnership cash and
property as provided in Section 12.3 in connection with the liquidation of the
Partnership, the Partnership shall be terminated and the Certificate of Limited
Partnership and all qualifications of the Partnership as a foreign limited
partnership in jurisdictions other than the State of Delaware shall be canceled
and such other actions as may be necessary to terminate the Partnership shall be
taken.

        Section 12.5    Return of Contributions.    The General Partner shall
not be personally liable for, and shall have no obligation to contribute or loan
any monies or property to the Partnership to enable it to effectuate, the return
of the Capital Contributions of the Limited Partners or Unitholders, or any
portion thereof, it being expressly understood that any such return shall be
made solely from Partnership assets.

        Section 12.6    Waiver of Partition.    To the maximum extent permitted
by law, each Partner hereby waives any right to partition of the Partnership
property.

        Section 12.7    Capital Account Restoration.    No Limited Partner shall
have any obligation to restore any negative balance in its Capital Account upon
liquidation of the Partnership. The General Partner shall be obligated to
restore any negative balance in its Capital Account upon liquidation of its
interest in the Partnership by the end of the taxable year of the Partnership
during which such liquidation occurs, or, if later, within 90 days after the
date of such liquidation.

ARTICLE XIII
AMENDMENT OF PARTNERSHIP AGREEMENT;
MEETINGS; RECORD DATE

        Section 13.1    Amendment to be Adopted Solely by the General
Partner.    Each Partner agrees that the General Partner, without the approval
of any Partner or Assignee, may amend any provision of this Agreement and
execute, swear to, acknowledge, deliver, file and record whatever documents may
be required in connection therewith, to reflect:

        (a)   a change in the name of the Partnership, the location of the
principal place of business of the Partnership, the registered agent of the
Partnership or the registered office of the Partnership;

        (b)   admission, substitution, withdrawal or removal of Partners, as
applicable, in accordance with this Agreement;

        (c)   a change that, in the sole discretion of the General Partner, is
necessary or advisable to qualify or continue the qualification of the
Partnership as a limited partnership or a partnership in which the Limited
Partners have limited liability under the laws of any state or to ensure that
the Group Members will not be treated as associations taxable as corporations or
otherwise taxed as entities for federal income tax purposes;

        (d)   a change that, in the discretion of the General Partner, (i) does
not adversely affect the Limited Partners (including any particular class of
Partnership Interests as compared to other classes of Partnership Interests) in
any material respect, (ii) is necessary or advisable to (A) satisfy any
requirements, conditions or guidelines contained in any opinion, directive,
order, ruling or regulation of any federal or state agency or judicial authority
or contained in any federal or state statute (including the Delaware Act) or
(B) facilitate the trading of the Units (including the division of any class or
classes of Outstanding Voting Units into different classes to facilitate
uniformity of tax consequences within such classes of Units) or comply with any
rule, regulation, guideline or requirement of any National Securities Exchange
on which the Units are or will be listed for trading, compliance with any of
which the General Partner determines in its discretion to be in the best
interests of the Partnership and the Limited Partners, (iii) is necessary or
advisable in connection with action taken by the General

A-40

--------------------------------------------------------------------------------

Partner pursuant to Section 5.5 or (iv) is required to effect the intent of the
provisions of this Agreement or is otherwise contemplated by this Agreement;

        (e)   a change in the fiscal year or taxable year of the Partnership and
any changes that, in the discretion of the General Partner, are necessary or
advisable as a result of a change in the fiscal year or taxable year of the
Partnership including, if the General Partner shall so determine, a change in
the definition of "Quarter" and the dates on which distributions are to be made
by the Partnership;

        (f)    an amendment that is necessary, in the Opinion of Counsel, to
prevent the Partnership, or the General Partner or its directors, officers,
trustees or agents from in any manner being subjected to the provisions of the
Investment Company Act of 1940, as amended, the Investment Advisers Act of 1940,
as amended, or "plan asset" regulations adopted under the Employee Retirement
Income Security Act of 1974, as amended, regardless of whether such are
substantially similar to plan asset regulations currently applied or proposed by
the United States Department of Labor;

        (g)   an amendment that, in the discretion of the General Partner, is
necessary or advisable in connection with the authorization of issuance of any
class or series of Partnership Securities pursuant to Section 5.4;

        (h)   any amendment expressly permitted in this Agreement to be made by
the General Partner acting alone;

        (i)    an amendment effected, necessitated or contemplated by a Merger
Agreement approved in accordance with Section 14.3;

        (j)    an amendment that, in the discretion of the General Partner, is
necessary or advisable to reflect, account for and deal with appropriately the
formation by the Partnership of, or investment by the Partnership in, any
corporation, partnership, joint venture, limited liability company or other
entity, in connection with the conduct by the Partnership of activities
permitted by the terms of Section 2.4;

        (k)   a merger or conveyance pursuant to Section 14.3(d); or

        (l)    any other amendments substantially similar to the foregoing.

        Section 13.2    Amendment Procedures.    Except as provided in Sections
13.1 and 13.3, all amendments to this Agreement shall be made in accordance with
the following requirements. Amendments to this Agreement may be proposed only by
or with the consent of the General Partner which consent may be given or
withheld in its sole discretion. A proposed amendment shall be effective upon
its approval by the majority of the Outstanding Voting Units unless a greater or
different percentage is required under this Agreement or by Delaware law. Each
proposed amendment that requires the approval of the holders of a specified
percentage of Outstanding Voting Units shall be set forth in a writing that
contains the text of the proposed amendment. If such a Voting amendment is
proposed, the General Partner shall seek the written approval of the requisite
percentage of Outstanding Voting Units or call a meeting of the Unitholders to
consider and vote on such proposed amendment. The General Partner shall notify
all Record Holders upon final adoption of any such proposed amendments.

        Section 13.3    Amendment Requirements.    

        (a)   Notwithstanding the provisions of Sections 13.1 and 13.2, no
provision of this Agreement that establishes a percentage of Outstanding Voting
Units (including Units deemed owned by the General Partner) required to take any
action shall be amended, altered, changed, repealed or rescinded in any respect
that would have the effect of reducing such voting percentage unless such
amendment is approved by the written consent or the affirmative vote of holders
of Outstanding Voting Units whose aggregate Outstanding Voting Units constitute
not less than the voting requirement sought to be reduced.

A-41

--------------------------------------------------------------------------------

        (b)   Notwithstanding the provisions of Sections 13.1 and 13.2, no
amendment to this Agreement may (i) enlarge the obligations of any Limited
Partner without its consent, unless such shall be deemed to have occurred as a
result of an amendment approved pursuant to Section 13.3(c), (ii) enlarge the
obligations of, restrict in any way any action by or rights of, or reduce in any
way the amounts distributable, reimbursable or otherwise payable to, the General
Partner or any of its Affiliates without its consent, which consent may be given
or withheld in its sole discretion, (iii) change Section 12.1(b), or (iv) change
the term of the Partnership or, except as set forth in Section 12.1(b), give any
Person the right to dissolve the Partnership.

        (c)   Except as provided in Section 14.3, and without limitation of the
General Partner's authority to adopt amendments to this Agreement without the
approval of any Partners or Assignees as contemplated in Section 13.1, any
amendment that would have a material adverse effect on the rights or preferences
of any class of Partnership Interests in relation to other classes of
Partnership Interests must be approved by the holders of not less than a
majority of the Outstanding Partnership Interests of the class affected.

        (d)   Notwithstanding any other provision of this Agreement, except for
amendments pursuant to Section 13.1 and except as otherwise provided by
Section 14.3(b), no amendments shall become effective without the approval of
the holders of at least 90% of the Outstanding Voting Units voting as a single
class unless the Partnership obtains an Opinion of Counsel to the effect that
such amendment will not affect the limited liability of any Limited Partner
under applicable law.

        (e)   Except as provided in Section 13.1, this Section 13.3 shall only
be amended with the approval of the holders of at least 90% of the Outstanding
Voting Units.

        Section 13.4    Common Unitholder Meetings.    

        (a)   All acts of Limited Partners to be taken pursuant to this
Agreement shall be taken in the manner provided in this Article XIII.

        (b)   Special meetings of the Limited Partners may be called by the
General Partner or by Limited Partners owning 20% or more of the Outstanding
Voting Units of the class or classes for which a meeting is proposed. Limited
Partners shall call a special meeting by delivering to the General Partner (if
there is a General Partner at such time) one or more requests in writing stating
that the signing Limited Partners wish to call a special meeting and indicating
the general or specific purposes (including the election of directors to the
Board of Directors, as necessary), for which the special meeting is to be
called. Within 60 days after receipt of such a call from Limited Partners or
within such greater time as may be reasonably necessary for the Partnership to
comply with any statutes, rules, regulations, listing agreements or similar
requirements governing the holding of a meeting or the solicitation of proxies
for use at such a meeting, the General Partner (or, if there is no General
Partner at such time, Limited Partners owning at least 20% of the Outstanding
Voting Units of the class or classes for which the meeting is proposed) shall
send a notice of the meeting to the Limited Partners either directly or
indirectly through the Transfer Agent. A special meeting shall be held at a time
and place determined by the General Partner (or, if there is no General Partner
at such time, Limited Partners owning at least 20% of the Outstanding Voting
Units of the class or classes for which the meeting is proposed) on a date not
less than 10 days nor more than 60 days after the mailing of notice of the
meeting. Limited Partners shall not vote on matters that would cause the Limited
Partners to be deemed to be taking part in the management and control of the
business and affairs of the Partnership so as to jeopardize the Limited
Partners' limited liability under the Delaware Act or the law of any other state
in which the Partnership is qualified to do business.

        (c)   (i) An annual meeting of the Limited Partners holding Voting Units
for the election of directors to the Board of Directors and such other matters
as the Board of Directors shall submit to a vote of the Limited Partners holding
Voting Units shall be held in June of each year or at such other

A-42

--------------------------------------------------------------------------------

date and time as may be fixed from time to time by the General Partner (or, if
there is no General Partner at such time, Limited Partners owning at least 20%
of the Outstanding Voting Units of the class or classes for which the meeting is
proposed) at such place within or without the State of Delaware as may be fixed
from time to time by the General Partner (or, if there is no General Partner at
such time, Limited Partners owning at least 20% of the Outstanding Voting Units
of the class or classes for which the meeting is proposed) and all as stated in
the notice of the meeting. Notice of the annual meeting shall be given in
accordance with Section 13.5 not less than 10 days nor more than 60 days prior
to the date of such meeting.

         (ii)  The Limited Partners holding Voting Units shall vote together as
a single class. The Limited Partners entitled to vote shall elect by a plurality
of the votes cast at such meeting persons to serve on the Board of Directors of
the General Partner who are nominated in accordance with the provisions of this
Section 13.4(c). The exercise by a Limited Partner of the right to elect the
Directors and any other rights afforded to such Limited Partner under this
Section 13.4(c) shall be in such Limited Partner's capacity as a limited partner
of the Partnership and shall not cause a Limited Partner to be deemed to be
taking part in the management and control of the business and affairs of the
Partnership so as to jeopardize such Limited Partner's limited liability under
the Delaware Act or the law of any other state in which the Partnership is
qualified to do business.

        (iii)  Each Limited Partner holding Voting Units shall be entitled to
one vote for each Outstanding Unit that is registered in the name of such
Limited Partner on the Record Date for such meeting; provided, however, that the
General Partner, the Partnership and their Affiliates shall not be entitled to
vote Units that are otherwise entitled to vote at any meeting of the Unitholders
and any such Units that are not entitled to be voted pursuant to this provision
shall not be deemed to be Outstanding for purposes of determining a quorum under
Section 13.9.

        (iv)  The number of Directors that shall constitute the whole Board of
Directors of the General Partner shall not be less than seven and not more than
eleven as shall be established from time to time by a resolution adopted by a
majority of the Directors; provided, however, that no decrease shall shorten the
term of any incumbent Director. Unless otherwise previously elected at a special
meeting, at each annual meeting of the Limited Partners, Directors shall be
elected to hold office until the next annual meeting.

         (v)  Each Director shall hold office for the term for which such
Director is elected and thereafter until such Director's successor shall have
been duly elected and qualified, or until such Director's earlier death,
resignation or removal. Any vacancies may be filled, until the next annual
meeting, by a majority of the remaining Directors then in office. A Director may
be removed only for cause and only upon a vote of the majority of the remaining
Directors then in office.

        (vi)  If the Commission promulgates a rule that provides for nominations
by shareholders of publicly traded companies of persons for election to the
board of directors, the Partnership and the General Partner shall adopt such
rule as applied to a corporation without regard to any exemptions provided to
limited partnerships.

       (vii)  This Section 13.4(c) shall not be deemed in any way to limit or
impair the ability of the Board of Directors to adopt a "poison pill" or
unitholder or other similar rights plan with respect to the Partnership, whether
such poison pill or plan contains "dead hand" provisions, "no hand" provisions
or other provisions relating to the redemption of the poison pill or plan, in
each case as such terms are used under Delaware common law.

      (viii)  The General Partner shall use its commercially reasonable best
efforts to take such action as shall be necessary or appropriate to give effect
to and implement the provisions of this Section 13.4(c), including, without
limitation, amending the limited liability company agreement of the General
Partner.

A-43

--------------------------------------------------------------------------------

        (ix)  This Article XIII may not be amended except upon the prior
approval of Limited Partners that hold 80% of the Outstanding Voting Units.

         (x)  If the General Partner delegates to an existing or newly formed
wholly-owned subsidiary the power and authority to manage and control the
business and affairs of the Partnership Group, the foregoing provisions of this
Section 13.4(c) shall be applicable with respect to the Board of Directors or
other governing body of such Subsidiary.

        Section 13.5    Notice of a Meeting.    Notice of a meeting called
pursuant to Section 13.4 shall be given to the Record Holders of the class or
classes of Units for which a meeting is proposed in writing by mail or other
means of written communication in accordance with Section 15.1. The notice shall
be deemed to have been given at the time when deposited in the mail or sent by
other means of written communication.

        Section 13.6    Record Date.    For purposes of determining the Limited
Partners entitled to notice of or to vote at a meeting of the Limited Partners
or to give approvals without a meeting as provided in Section 13.11 the General
Partner (or, if there is no General Partner at such time, Limited Partners
owning at least 20% of the Outstanding Voting Units of the class or classes for
which the meeting is proposed or which would have the right to vote on such
action, as applicable) may set a Record Date, which shall not be less than 10
nor more than 60 days before (a) the date of the meeting (unless such
requirement conflicts with any rule, regulation, guideline or requirement of any
National Securities Exchange on which the Limited Partner Interests are listed
for trading, in which case the rule, regulation, guideline or requirement of
such exchange shall govern) or (b) in the event that approvals are sought
without a meeting, the date by which Limited Partners are requested in writing
by the General Partner (or, if there is no General Partner at such time, Limited
Partners owning at least 20% of the Outstanding Voting Units of the class or
classes which would have the right to vote on such action) to give such
approvals.

        Section 13.7    Adjournment.    When a meeting is adjourned to another
time or place, notice need not be given of the adjourned meeting and a new
Record Date need not be fixed, if the time and place thereof are announced at
the meeting at which the adjournment is taken, unless such adjournment shall be
for more than 45 days. At the adjourned meeting, the Partnership may transact
any business which might have been transacted at the original meeting. If the
adjournment is for more than 45 days or if a new Record Date is fixed for the
adjourned meeting, a notice of the adjourned meeting shall be given in
accordance with this Article XIII.

        Section 13.8    Waiver of Notice; Approval of Meeting; Approval of
Minutes.    The transactions of any meeting of Limited Partners, however called
and noticed, and whenever held, shall be as valid as if it had occurred at a
meeting duly held after regular call and notice, if a quorum is present either
in person or by proxy, and if, either before or after the meeting, Limited
Partners representing such quorum who were present in person or by proxy and
entitled to vote, sign a written waiver of notice or an approval of the holding
of the meeting or an approval of the minutes thereof. All waivers and approvals
shall be filed with the Partnership records or made a part of the minutes of the
meeting. Attendance of a Limited Partner at a meeting shall constitute a waiver
of notice of the meeting, except when the Limited Partner does not approve, at
the beginning of the meeting, of the transaction of any business because the
meeting is not lawfully called or convened; and except that attendance at a
meeting is not a waiver of any right to disapprove the consideration of matters
required to be included in the notice of the meeting, but not so included, if
the disapproval is expressly made at the meeting.

        Section 13.9    Quorum.    The holders of a majority of the Outstanding
Voting Units of the class or classes for which a meeting has been called
represented in person or by proxy shall constitute a quorum at a meeting of
Limited Partners of such class or classes unless any such action by the Limited
Partners requires approval by holders of a greater percentage of such Voting
Units, in which case the quorum shall be such greater percentage. At any meeting
of the Limited Partners duly called and held

A-44

--------------------------------------------------------------------------------

in accordance with this Agreement at which a quorum is present, the act of
Limited Partners holding Outstanding Voting Units that in the aggregate
represent a majority of the Outstanding Voting Units entitled to vote and be
present in person or by proxy at such meeting shall be deemed to constitute the
act of all Limited Partners, unless a greater or different percentage is
required with respect to such action under the provisions of this Agreement, in
which case the act of the Limited Partners holding Outstanding Voting Units that
in the aggregate represent at least such greater or different percentage shall
be required. The Limited Partners present at a duly called or held meeting at
which a quorum is present may continue to transact business until adjournment,
notwithstanding the withdrawal of enough Limited Partners to leave less than a
quorum, if any action taken (other than adjournment) is approved by the required
percentage of Outstanding Voting Units specified in this Agreement. In the
absence of a quorum any meeting of Limited Partners may be adjourned from time
to time by the affirmative vote of holders of at least a majority of the
Outstanding Voting Units entitled to vote at such meeting represented either in
person or by proxy, but no other business may be transacted, except as provided
in Section 13.7.

        Section 13.10    Conduct of a Meeting.    The General Partner (or, if
there is no General Partner at such time, Limited Partners owning at least 20%
of the Outstanding Voting Units of the class or classes for which the meeting is
proposed) shall have full power and authority concerning the manner of
conducting any meeting of the Limited Partners or solicitation of approvals in
writing, including the determination of Persons entitled to vote, the existence
of a quorum, the satisfaction of the requirements of Section 13.4, the conduct
of voting, the validity and effect of any proxies and the determination of any
controversies, votes or challenges arising in connection with or during the
meeting or voting. The General Partner (or, if there is no General Partner at
such time, Limited Partners owning at least 20% of the Outstanding Voting Units
of the class or classes for which the meeting is proposed) shall designate a
Person to serve as chairman of any meeting and shall further designate a Person
to take the minutes of any meeting. All minutes shall be kept with the records
of the Partnership maintained by the General Partner. The General Partner (or,
if there is no General Partner at such time, Limited Partners owning at least
20% of the Outstanding Voting Units of the class or classes for which the
meeting is proposed) may make such other regulations consistent with applicable
law and this Agreement as it may deem advisable concerning the conduct of any
meeting of the Limited Partners or solicitation of approvals in writing,
including regulations in regard to the appointment of proxies, the appointment
and duties of inspectors of votes and approvals, the submission and examination
of proxies and other evidence of the right to vote, and the revocation of
approvals in writing.

        Section 13.11    Action Without a Meeting.    If authorized by the
General Partner (or, if there is no General Partner at such time, Limited
Partners owning at least 20% of the Outstanding Voting Units of the class or
classes which would have the right to vote on such action), any action that may
be taken at a meeting of the Limited Partners may be taken without a meeting if
an approval in writing setting forth the action so taken is signed by Limited
Partners owning not less than the minimum percentage of the Outstanding Voting
Units that would be necessary to authorize or take such action at a meeting at
which all the Limited Partners were present and voted (unless such provision
conflicts with any rule, regulation, guideline or requirement of any National
Securities Exchange on which the Voting Units are listed for trading, in which
case the rule, regulation, guideline or requirement of such exchange shall
govern). Prompt notice of the taking of action without a meeting shall be given
to the Limited Partners who have not approved in writing. The General Partner
(or, if there is no General Partner at such time, Limited Partners owning at
least 20% of the Outstanding Voting Units of the class or classes which would
have the right to vote on such action) may specify that any written ballot
submitted to Limited Partners for the purpose of taking any action without a
meeting shall be returned to the Partnership within the time period, which shall
be not less than 20 days, specified by the General Partner (or, if there is no
General Partner at such time, Limited Partners owning at least 20% of the
Outstanding Voting Units of the class or classes which would have the right to
vote on such action). If

A-45

--------------------------------------------------------------------------------

a ballot returned to the Partnership does not vote all of the Voting Units held
by the Limited Partners, the Partnership shall be deemed to have failed to
receive a ballot for the Voting Units that were not voted. If approval of the
taking of any action by the Limited Partners is solicited by any Person other
than by or on behalf of the General Partner (or, if there is no General Partner
at such time, Limited Partners owning at least 20% of the Outstanding Voting
Units of the class or classes which would have the right to vote on such
action), the written approvals shall have no force and effect unless and until
(a) they are deposited with the Partnership in care of the General Partner,
(b) approvals sufficient to take the action proposed are dated as of a date not
more than 90 days prior to the date sufficient approvals are deposited with the
Partnership and (c) an Opinion of Counsel is delivered to the General Partner to
the effect that the exercise of such right and the action proposed to be taken
with respect to any particular matter (i) will not cause the Limited Partners to
be deemed to be taking part in the management and control of the business and
affairs of the Partnership so as to jeopardize the Limited Partners' limited
liability, and (ii) is otherwise permissible under the state statutes then
governing the rights, duties and liabilities of the Partnership and the
Partners.

        Section 13.12    Voting and Other Rights.    

        (a)   Only those Record Holders of the Voting Units on the Record Date
set pursuant to Section 13.6 (and also subject to the limitations contained in
the definition of "Outstanding") shall be entitled to notice of, and to vote at,
a meeting of Limited Partners or to act with respect to matters as to which the
holders of the Outstanding Voting Units have the right to vote or to act. All
references in this Agreement to votes of, or other acts that may be taken by,
the Outstanding Voting Units shall be deemed to be references to the votes or
acts of the Record Holders of such Outstanding Voting Units.

        (b)   With respect to Voting Units that are held for a Person's account
by another Person (such as a broker, dealer, bank, trust company or clearing
corporation, or an agent of any of the foregoing), in whose name such Voting
Units are registered, such other Person shall, in exercising the voting rights
in respect of such Voting Units on any matter, and unless the arrangement
between such Persons provides otherwise, vote such Voting Units in favor of, and
at the direction of, the Person who is the beneficial owner, and the Partnership
shall be entitled to assume it is so acting without further inquiry. The
provisions of this Section 13.12(b) (as well as all other provisions of this
Agreement) are subject to the provisions of Section 4.3.

ARTICLE XIV
MERGER

        Section 14.1    Authority.    The Partnership may merge or consolidate
with one or more corporations, limited liability companies, business trusts or
associations, real estate investment trusts, common law trusts or unincorporated
businesses, including a general partnership or limited partnership, formed under
the laws of the State of Delaware or any other state of the United States of
America, pursuant to a written agreement of merger or consolidation ("Merger
Agreement") in accordance with this Article XIV.

        Section 14.2    Procedure for Merger or Consolidation.    Merger or
consolidation of the Partnership pursuant to this Article XIV requires the prior
approval of the General Partner. If the General Partner shall determine, in the
exercise of its discretion, to consent to the merger or consolidation, the
General Partner shall approve the Merger Agreement, which shall set forth:

        (a)   the names and jurisdictions of formation or organization of each
of the business entities proposing to merge or consolidate;

        (b)   the name and jurisdiction of formation or organization of the
business entity that is to survive the proposed merger or consolidation (the
"Surviving Business Entity");

        (c)   the terms and conditions of the proposed merger or consolidation;

A-46

--------------------------------------------------------------------------------

        (d)   the manner and basis of exchanging or converting the equity
securities of each constituent business entity for, or into, cash, property or
general or limited partner interests, rights, securities or obligations of the
Surviving Business Entity; and (i) if any general or limited partner interests,
securities or rights of any constituent business entity are not to be exchanged
or converted solely for, or into, cash, property or general or limited partner
interests, rights, securities or obligations of the Surviving Business Entity,
the cash, property or general or limited partner interests, rights, securities
or obligations of any limited partnership, corporation, trust or other entity
(other than the Surviving Business Entity) which the holders of such general or
limited partner interests, securities or rights are to receive in exchange for,
or upon conversion of their general or limited partner interests, securities or
rights, and (ii) in the case of securities represented by certificates, upon the
surrender of such certificates, which cash, property or general or limited
partner interests, rights, securities or obligations of the Surviving Business
Entity or any general or limited partnership, corporation, trust or other entity
(other than the Surviving Business Entity), or evidences thereof, are to be
delivered;

        (e)   a statement of any changes in the constituent documents or the
adoption of new constituent documents (the articles or certificate of
incorporation, articles of trust, declaration of trust, certificate or agreement
of limited partnership or other similar charter or governing document) of the
Surviving Business Entity to be effected by such merger or consolidation;

        (f)    the effective time of the merger, which may be the date of the
filing of the certificate of merger pursuant to Section 14.4 or a later date
specified in or determinable in accordance with the Merger Agreement (provided,
however, that if the effective time of the merger is to be later than the date
of the filing of the certificate of merger, the effective time shall be fixed no
later than the time of the filing of the certificate of merger and stated
therein); and

        (g)   such other provisions with respect to the proposed merger or
consolidation as are deemed necessary or appropriate by the General Partner.

        Section 14.3    Approval by Limited Partners of Merger or
Consolidation.    

        (a)   Except as provided in Section 14.3(d), the General Partner, upon
its approval of the Merger Agreement, shall direct that the Merger Agreement be
submitted to a vote of Limited Partners, whether at a special meeting or by
written consent, in either case in accordance with the requirements of
Article XIII. A copy or a summary of the Merger Agreement shall be included in
or enclosed with the notice of a special meeting or the written consent.

        (b)   Except as provided in Section 14.3(d), the Merger Agreement shall
be approved upon receiving the affirmative vote or consent of the holders of a
majority of the Outstanding Voting Units unless the Merger Agreement contains
any provision that, if contained in an amendment to this Agreement, the
provisions of this Agreement or the Delaware Act would require for its approval
the vote or consent of a greater percentage of the Outstanding Voting Units or
of any class of Limited Partners, in which case such greater percentage vote or
consent shall be required for approval of the Merger Agreement.

        (c)   Except as provided in Section 14.3(d), after such approval by vote
or consent of the Limited Partners, and at any time prior to the filing of the
certificate of merger pursuant to Section 14.4, the merger or consolidation may
be abandoned pursuant to provisions therefor, if any, set forth in the Merger
Agreement.

        (d)   Notwithstanding anything else contained in this Article XIV or in
this Agreement, the General Partner is permitted, in its discretion, without
Limited Partner approval, to merge the Partnership or any Group Member into, or
convey all of the Partnership's assets to, another limited liability entity
which shall be newly formed and shall have no assets, liabilities or operations
at the time of such Merger other than those it receives from the Partnership or
other Group Member if (i) the General Partner has received an Opinion of Counsel
that the merger or conveyance, as the case may be, would

A-47

--------------------------------------------------------------------------------

not result in the loss of the limited liability of any Limited Partner or any
Group Member or cause the Partnership or any Group Member to be treated as an
association taxable as a corporation or otherwise to be taxed as an entity for
federal income tax purposes (to the extent not previously treated as such),
(ii) the sole purpose of such merger or conveyance is to effect a mere change in
the legal form of the Partnership into another limited liability entity and
(iii) the governing instruments of the new entity provide the Limited Partners
and the General Partner with the same rights and obligations as are herein
contained.

        Section 14.4    Certificate of Merger.    Upon the required approval by
the General Partner and the Unitholders of a Merger Agreement, a certificate of
merger shall be executed and filed with the Secretary of State of the State of
Delaware in conformity with the requirements of the Delaware Act.

        Section 14.5    Effect of Merger.    

        (a)   At the effective time of the certificate of merger:

          (i)  all of the rights, privileges and powers of each of the business
entities that has merged or consolidated, and all property, real, personal and
mixed, and all debts due to any of those business entities and all other things
and causes of action belonging to each of those business entities, shall be
vested in the Surviving Business Entity and after the merger or consolidation
shall be the property of the Surviving Business Entity to the extent they were
of each constituent business entity;

         (ii)  the title to any real property vested by deed or otherwise in any
of those constituent business entities shall not revert and is not in any way
impaired because of the merger or consolidation;

        (iii)  all rights of creditors and all liens on or security interests in
property of any of those constituent business entities shall be preserved
unimpaired; and

        (iv)  all debts, liabilities and duties of those constituent business
entities shall attach to the Surviving Business Entity and may be enforced
against it to the same extent as if the debts, liabilities and duties had been
incurred or contracted by it.

        (b)   A merger or consolidation effected pursuant to this Article shall
not be deemed to result in a transfer or assignment of assets or liabilities
from one entity to another.

ARTICLE XV
GENERAL PROVISIONS

        Section 15.1    Addresses and Notices.    Any notice, demand, request,
report or proxy materials required or permitted to be given or made to a Partner
or Assignee under this Agreement shall be in writing and shall be deemed given
or made when delivered in person or when sent by first class United States mail
or by other means of written communication to the Partner or Assignee at the
address described below. Any notice, payment or report to be given or made to a
Partner or Assignee hereunder shall be deemed conclusively to have been given or
made, and the obligation to give such notice or report or to make such payment
shall be deemed conclusively to have been fully satisfied, upon sending of such
notice, payment or report to the Record Holder of such Partnership Securities at
his address as shown on the records of the Transfer Agent or as otherwise shown
on the records of the Partnership, regardless of any claim of any Person who may
have an interest in such Partnership Securities by reason of any assignment or
otherwise. An affidavit or certificate of making of any notice, payment or
report in accordance with the provisions of this Section 15.1 executed by the
General Partner, the Transfer Agent or the mailing organization shall be prima
facie evidence of the giving or making of such notice, payment or report. If any
notice, payment or report addressed to a Record Holder at the address of such
Record Holder appearing on the books and records of the Transfer

A-48

--------------------------------------------------------------------------------

Agent or the Partnership is returned by the United States Postal Service marked
to indicate that the United States Postal Service is unable to deliver it, such
notice, payment or report and any subsequent notices, payments and reports shall
be deemed to have been duly given or made without further mailing (until such
time as such Record Holder or another Person notifies the Transfer Agent or the
Partnership of a change in his address) if they are available for the Partner or
Assignee at the principal office of the Partnership for a period of one year
from the date of the giving or making of such notice, payment or report to the
other Partners and Assignees. Any notice to the Partnership shall be deemed
given if received by the General Partner at the principal office of the
Partnership designated pursuant to Section 2.3. The General Partner may rely and
shall be protected in relying on any notice or other document from a Partner,
Assignee or other Person if believed by it to be genuine.

        Section 15.2    Further Action.    The parties shall execute and deliver
all documents, provide all information and take or refrain from taking action as
may be necessary or appropriate to achieve the purposes of this Agreement.

        Section 15.3    Binding Effect.    This Agreement shall be binding upon
and inure to the benefit of the parties hereto and their heirs, executors,
administrators, successors, legal representatives and permitted assigns.

        Section 15.4    Integration.    This Agreement constitutes the entire
agreement among the parties hereto pertaining to the subject matter hereof and
supersedes all prior agreements and understandings pertaining thereto.

        Section 15.5    Creditors.    None of the provisions of this Agreement
shall be for the benefit of, or shall be enforceable by, any creditor of the
Partnership.

        Section 15.6    Waiver.    No failure by any party to insist upon the
strict performance of any covenant, duty, agreement or condition of this
Agreement or to exercise any right or remedy consequent upon a breach thereof
shall constitute waiver of any such breach of any other covenant, duty,
agreement or condition.

        Section 15.7    Counterparts.    This Agreement may be executed in
counterparts, all of which together shall constitute an agreement binding on all
the parties hereto, notwithstanding that all such parties are not signatories to
the original or the same counterpart. Each party shall become bound by this
Agreement immediately upon affixing its signature hereto or, in the case of a
Person acquiring a Unit, upon accepting the certificate evidencing such Unit or
executing and delivering a Transfer Application as herein described,
independently of the signature of any other party.

        Section 15.8    Applicable Law.    This Agreement shall be construed in
accordance with and governed by the laws of the State of Delaware, without
regard to the principles of conflicts of law.

        Section 15.9    Invalidity of Provisions.    If any provision of this
Agreement is or becomes invalid, illegal or unenforceable in any respect, the
validity, legality and enforceability of the remaining provisions contained
herein shall not be affected thereby.

        Section 15.10    Consent of Partners.    Each Partner hereby expressly
consents and agrees that, whenever in this Agreement it is specified that an
action may be taken upon the affirmative vote or consent of less than all of the
Partners, such action may be so taken upon the concurrence of less than all of
the Partners and each Partner shall be bound by the results of such action.

[REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK.]

A-49

--------------------------------------------------------------------------------

        The parties hereto have executed this Agreement as of the date first
written above.

    GENERAL PARTNER:
 
 
MARKWEST ENERGY GP, L.L.C.
 
 
By:
 
    

--------------------------------------------------------------------------------

        Name: Nancy Buese         Title: Senior Vice President and Chief
Financial Officer
 
 
LIMITED PARTNERS:
 
 
All Limited Partners now and hereafter admitted as Limited Partners of the
Partnership, pursuant to powers of attorney now and hereafter executed in favor
of, and granted and delivered to the General Partner.
 
 
MARKWEST ENERGY GP, L.L.C.
 
 
By:
 
    

--------------------------------------------------------------------------------

        Name: Nancy Buese         Title: Senior Vice President and Chief
Financial Officer
 
 
MARKWEST HYDROCARBON, INC.
 
 
By:
 
    

--------------------------------------------------------------------------------

        Name: Nancy Buese         Title: Senior Vice President and Chief
Financial Officer

A-50

--------------------------------------------------------------------------------

EXHIBIT A

to the Third Amended and Restated
Agreement of Limited Partnership of
MarkWest Energy Partners, L.P.
Certificate Evidencing Common Units
Representing Limited Partner Interests in
MarkWest Energy Partners, L.P.

No.   Common Units

        In accordance with Section 4.1 of the Third Amended and Restated
Agreement of Limited Partnership of MarkWest Energy Partners, L.P., as amended,
supplemented or restated from time to time (the "Partnership Agreement"),
MarkWest Energy Partners, L.P., a Delaware limited partnership (the
"Partnership"), hereby certifies that                        (the "Holder") is
the registered owner of Common Units representing limited partner interests in
the Partnership (the "Common Units") transferable on the books of the
Partnership, in person or by duly authorized attorney, upon surrender of this
Certificate properly endorsed and accompanied by a properly executed application
for transfer of the Common Units represented by this Certificate. The rights,
preferences and limitations of the Common Units are set forth in, and this
Certificate and the Common Units represented hereby are issued and shall in all
respects be subject to the terms and provisions of, the Partnership Agreement.
Copies of the Partnership Agreement are on file at, and will be furnished
without charge on delivery of written request to the Partnership at, the
principal office of the Partnership located at 155 Inverness Drive West, Suite
200, Englewood, Colorado 80112. Capitalized terms used herein but not defined
shall have the meanings given them in the Partnership Agreement.

        The Holder, by accepting this Certificate, is deemed to have
(i) requested admission as, and agreed to become, a Limited Partner and to have
agreed to comply with and be bound by and to have executed the Partnership
Agreement, (ii) represented and warranted that the Holder has all right, power
and authority and, if an individual, the capacity necessary to enter into the
Partnership Agreement, (iii) granted the powers of attorney provided for in the
Partnership Agreement and (iv) made the waivers and given the consents and
approvals contained in the Partnership Agreement.

        This Certificate shall not be valid far any purpose unless it has been
countersigned and registered by the Transfer Agent and Registrar.

Dated:   MarkWest Energy Partners, L.P.
Countersigned and Registered by:
 
By:
MarkWest Energy GP, L.L.C., its General Partner
    

--------------------------------------------------------------------------------

 
By:
    

--------------------------------------------------------------------------------

as Transfer Agent and Registrar   Name:
By:
 
    

--------------------------------------------------------------------------------

 
By:
    

--------------------------------------------------------------------------------

Authorized Signature   Secretary

A-51

--------------------------------------------------------------------------------

[Reverse of Certificate]

ABBREVIATIONS

        The following abbreviations, when used in the inscription on the face of
this Certificate, shall be construed as follows according to applicable laws or
regulations:

TEN COM -  as tenants in common   UNIF GIFT/TRANSFERS MIN ACT
TEN ENT -
as tenants by the entireties
 
    

--------------------------------------------------------------------------------

(Cust)
Custodian
    

--------------------------------------------------------------------------------

(Minor) JT TEN - as joint tenants with right of survivorship and not as tenants
in common   under Uniform Gifts/Transfers to CD Minors Act (State)

        Additional abbreviations, though not in the above list, may also be
used.

ASSIGNMENT OF COMMON UNITS
in
MARKWEST ENERGY PARTNERS, L.P.
IMPORTANT NOTICE REGARDING INVESTOR RESPONSIBILITIES
DUE TO TAX SHELTER STATUS OF
MARKWEST ENERGY PARTNERS, L.P.

        You have acquired an interest in MarkWest Energy Partners, L.P., 155
Inverness Drive West, Suite 200, Englewood, Colorado 80112, whose taxpayer
identification number is 20-0005456. The Internal Revenue Service has issued
MarkWest Energy Partners, L.P. the following tax shelter registration
number:                        .

        YOU MUST REPORT THIS REGISTRATION NUMBER TO THE INTERNAL REVENUE SERVICE
IF YOU CLAIM ANY DEDUCTION, LOSS, CREDIT OR OTHER TAX BENEFIT OR REPORT ANY
INCOME BY REASON OF YOUR INVESTMENT IN MARKWEST ENERGY PARTNERS, L.P.

        You must report the registration number as well as the name and taxpayer
identification number of MarkWest Energy Partners, L.P. on Form 8271. FORM 8271
MUST BE ATTACHED TO THE RETURN ON WHICH YOU CLAIM THE DEDUCTION, LOSS, CREDIT OR
OTHER TAX BENEFIT OR REPORT ANY INCOME BY REASON OF YOUR INVESTMENT IN MARKWEST
ENERGY PARTNERS, L.P.

        If you transfer your interest in MarkWest Energy Partners, L.P. to
another person, you are required by the Internal Revenue Service to keep a list
containing (a) that person's name, address and taxpayer identification number,
(b) the date on which you transferred the interest and (c) the name, address and
tax shelter registration number of MarkWest Energy Partners, L.P. If you do not
want to keep such a list, you must (1) send the information specified above to
the Partnership, which will keep the list for this tax shelter, and (2) give a
copy of this notice to the person to whom you transfer your interest. Your
failure to comply with any of the above-described responsibilities could result
in the imposition of a penalty under Section 6707(b) or 6708(a) of the Internal
Revenue Code of 1986, as amended, unless such failure is shown to be due to
reasonable cause.

        ISSUANCE OF A REGISTRATION NUMBER DOES NOT INDICATE THAT THIS INVESTMENT
OR THE CLAIMED TAX BENEFITS HAVE BEEN REVIEWED, EXAMINED OR APPROVED BY THE
INTERNAL REVENUE SERVICE.

A-52

--------------------------------------------------------------------------------

        FOR VALUE RECEIVED,                        hereby assigns, conveys,
sells and transfers unto

    

--------------------------------------------------------------------------------

(Please print or typewrite name and address of Assignee)       

--------------------------------------------------------------------------------

(Please insert Social Security or other identifying number of Assignee)

Common Units representing limited partner interests evidenced by this
Certificate, subject to the Partnership Agreement, and does hereby irrevocably
constitute and appoint                        as its attorney-in-fact with full
power of substitution to transfer the same on the books of MarkWest Energy
Partners, L.P.

Date:   NOTE:   The signature to any endorsement hereon must correspond with the
name as written upon the face of this Certificate in every particular, without
alteration, enlargement or change. THE SIGNATURE(S) MUST BE GUARANTEED BY AN
ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN
ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE
GUARANTEE MEDALLION PROGRAM), PURSUANT TO S.E.C. RULE 17d-15           

--------------------------------------------------------------------------------

(Signature)
  
  
    

--------------------------------------------------------------------------------

(Signature)

        No transfer of the Common Units evidenced hereby will be registered on
the books of the Partnership, unless the Certificate evidencing the Common Units
to be transferred is surrendered for registration or transfer and an Application
for Transfer of Common Units has been executed by a transferee either (a) on the
form set forth below or (b) on a separate application that the Partnership will
furnish on request without charge. A transferor of the Common Units shall have
no duty to the transferee with respect to execution of the transfer application
in order for such transferee to obtain registration of the transfer of the
Common Units.

A-53

--------------------------------------------------------------------------------

APPLICATION FOR TRANSFER OF COMMON UNITS

        The undersigned ("Assignee") hereby applies for transfer to the name of
the Assignee of the Common Units evidenced hereby.

        The Assignee (a) requests admission as a Substituted Limited Partner and
agrees to comply with and be bound by, and hereby executes, the Amended and
Restated Agreement of Limited Partnership of MarkWest Energy Partners, L.P. (the
"Partnership"), as amended, supplemented or restated to the date hereof (the
"Partnership Agreement"), (b) represents and warrants that the Assignee has all
right, power and authority and, if an individual, the capacity necessary to
enter into the Partnership Agreement, (c) appoints the General Partner of the
Partnership and, if a Liquidator shall be appointed, the Liquidator of the
Partnership as the Assignee's attorney-in-fact to execute, swear to, acknowledge
and file any document, including, without limitation, the Partnership Agreement
and any amendment thereto and the Certificate of Limited Partnership of the
Partnership and any amendment thereto, necessary or appropriate for the
Assignee's admission as a Substituted Limited Partner and as a party to the
Partnership Agreement, (d) gives the powers of attorney provided for in the
Partnership Agreement, and (e) makes the waivers and gives the consents and
approvals contained in the Partnership Agreement. Capitalized terms not defined
herein have the meanings assigned to such terms in the Partnership Agreement.

Date:    
    

--------------------------------------------------------------------------------

Social Security or other identifying number
 
    

--------------------------------------------------------------------------------

Signature of Assignee
    

--------------------------------------------------------------------------------

Purchase Price including commissions, if any
 
    

--------------------------------------------------------------------------------

Name and Address of Assignee

Type of Entity (check one):

o    Individual   o    Partnership   o    Corporation
o    Trust
 
o    Other (specify)
 
 

Nationality (check one):

o    U.S. Citizen, Resident or Domestic Entity
o    Foreign Corporation
 
o    Non-resident Alien
 
 

        If the U.S. Citizen, Resident or Domestic Entity box is checked, the
following certification must be completed.

        Under Section 1445(e) of the Internal Revenue Code of 1986, as amended
(the "Code"), the Partnership must withhold tax with respect to certain
transfers of property if a holder of an interest in the Partnership is a foreign
person. To inform the Partnership that no withholding is required with respect
to the undersigned interestholder's interest in it, the undersigned hereby
certifies the following (or, if applicable, certifies the following on behalf of
the interestholder).

Complete Either A or B:

A.Individual Interestholder

        1.     I am not a non-resident alien for purposes of U.S. income
taxation.

        2.     My U.S. taxpayer identification number (Social Security Number)
is                        .

A-54

--------------------------------------------------------------------------------

        3.     My home address is                        .

B.Partnership, Corporation or Other Interestholder

        1.                             is not a foreign corporation, foreign
partnership, foreign trust (Name of Interestholder) or foreign estate (as those
terms are defined in the Code and Treasury Regulations).

        2.     The interestholder's U.S. employer identification number
is                        .

        3.     The interestholder's office address and place of incorporation
(if applicable) is                        .

        The interestholder agrees to notify the Partnership within sixty
(60) days of the date the interestholder becomes a foreign person.

        The interestholder understands that this certificate may be disclosed to
the Internal Revenue Service by the Partnership and that any false statement
contained herein could be punishable by fine, imprisonment or both.

        Under penalties of perjury, I declare that I have examined this
certification and to the best of my knowledge and belief it is true, correct and
complete and, if applicable, I further declare that I have authority to sign
this document on behalf of:

    

--------------------------------------------------------------------------------

Name of Interestholder
    

--------------------------------------------------------------------------------

Signature and Date
    

--------------------------------------------------------------------------------

Title (if applicable)

        Note:    If the Assignee is a broker, dealer, bank, trust company,
clearing corporation, other nominee holder or an agent of any of the foregoing,
and is holding for the account of any other person, this application should be
completed by an officer thereof or, in the case of a broker or dealer, by a
registered representative who is a member of a registered national securities
exchange or a member of the National Association of Securities Dealers, Inc.,
or, in the case of any other nominee holder, a person performing a similar
function. If the Assignee is a broker, dealer, bank, trust company, clearing
corporation, other nominee owner or an agent of any of the foregoing, the above
certification as to any person for whom the Assignee will hold the Common Units
shall be made to the best of the Assignee's knowledge.

A-55

--------------------------------------------------------------------------------

Annex B

CERTIFICATE OF AMENDMENT
OF THE
CERTIFICATE OF INCORPORATION
OF
MARKWEST HYDROCARBON, INC.

        MarkWest Hydrocarbon, Inc., a Delaware corporation (the "Corporation"),
hereby certifies as follows:

        FIRST:    Article V, Section 1 of the Certificate of Incorporation of
the Corporation is hereby amended by adding new subsections (d) and (e) thereto,
which shall read in their entirety as follows:

"(d) Redemption of Common Stock.    Immediately prior to the Effective Time of
the Merger upon the effectiveness of this Amendment (as defined below) (the
"Redemption Date"), each share of Common Stock of the Corporation that would not
be converted into the Per Share Unit Consideration at the Effective Time of the
Merger (the "Redemption Shares"), pursuant to Section 3.1 of the Agreement and
Plan of Redemption and Merger, by and among the Corporation, MarkWest Energy
Partners, L.P. and MWEP, L.L.C. dated as of September 5, 2007 (the
"Redemption/Merger Agreement") shall be redeemed at a redemption price per share
equal to the Per Share Cash Consideration (the "Redemption Price"). All
capitalized terms used in Sections 1(d) and (e) (the "Amendment") that are not
defined herein shall have the meanings ascribed to such terms in the
Redemption/Merger Agreement. The Redemption Price shall be paid in accordance
with the procedures for payment of the Redemption Consideration to holders of
Certificates set forth in Section 3.5 of the Redemption/Merger Agreement. As of
the Redemption Date, all Redemption Shares shall no longer be deemed outstanding
and all rights with respect to such Redemption Shares shall cease and terminate,
except only the right of the holders thereof to receive the Per Share Cash
Consideration for each Redemption Share pursuant to and in accordance with the
terms of the Redemption/Merger Agreement.

(e) Appraisal Rights.    Pursuant to Section 262(c) of the Delaware General
Corporation Law, holders of shares of Common Stock shall be entitled to
appraisal rights as a result of the Amendment and, to the fullest extent
permitted by applicable law, holders of Common Stock who seek appraisal rights
as a result of the Amendment and thereafter fail to perfect, or otherwise waive,
withdraw or lose the right to seek appraisal rights with respect to shares of
Common Stock shall be entitled to receive as a result of such failure to
perfect, waiver, withdrawal or loss of appraisal rights only the cash and Common
Units that such holder would have otherwise been entitled to receive upon
redemption of the shares of Common Stock pursuant to Section 1(d) or upon
conversion of the shares of Common Stock pursuant to Section 3.1 of the
Redemption/Merger Agreement if such shares of Common Stock had been Non-Electing
Shares pursuant to and in accordance with the terms of the Redemption/Merger
Agreement, and nothing else."

        SECOND:    Said amendment was duly adopted in accordance with the
provisions of Section 242 of the Delaware General Corporation Law.

B-1

--------------------------------------------------------------------------------

        IN WITNESS WHEREOF, MarkWest Hydrocarbon, Inc. has caused this
Certificate of Amendment to be signed by its duly authorized officer,
this            day of                        , 2007.

    MARKWEST HYDROCARBON, INC.
 
 
By:
 
    

--------------------------------------------------------------------------------

Name:
Title:

B-2

--------------------------------------------------------------------------------

Annex C

CERTIFICATE OF INCORPORATION

OF

MARKWEST HYDROCARBON, INC.

Article I

        The name of the corporation is MarkWest Hydrocarbon, Inc.

Article II

        The address of its registered office in the State of Delaware is
Corporation Trust Center, 1209 Orange Street, in the City of Wilmington, 19801
County of New Castle. The name of its registered agent at such address is The
Corporation Trust Company.

Article III

        The nature of the business or purposes to be conducted or promoted by
the corporation is to engage in any lawful act or activity for which
corporations may be organized under the Delaware General Corporation Law.

Article IV

        The total number of shares of all classes of stock which the corporation
shall have authority to issue is One Thousand (1,000) shares of Common Stock of
the par value of One Cent ($.01) per share.

Article V

        The name and mailing address of the directors, who shall serve until the
first annual meeting of stockholders or until their successors are elected and
has qualified, are as follows:

Name

--------------------------------------------------------------------------------

  Address

--------------------------------------------------------------------------------

Frank M. Semple   1515 Arapahoe Street, Tower 2, Suite 700
Denver, Colorado 80202-2102
Nancy K. Buese
 
1515 Arapahoe Street, Tower 2, Suite 700
Denver, Colorado 80202-2102
Andrew L. Schroeder
 
1515 Arapahoe Street, Tower 2, Suite 700
Denver, Colorado 80202-2102

        The number of directors of the corporation shall be as specified in, or
determined in the manner provided in, the bylaws of the corporation. Election of
directors need not be by written ballot.

Article VI

        In furtherance of, and not in limitation of, the powers conferred by
statute, the Board of Directors is expressly authorized to adopt, amend or
repeal the bylaws of the corporation.

Article VII

        Whenever a compromise or arrangement is proposed between the corporation
and its creditors or any class of them and/or between the corporation and its
stockholders or any class of them, any court of equitable jurisdiction within
the State of Delaware may, on the application in a summary way of the

C-1

--------------------------------------------------------------------------------

corporation or of any creditor or stockholder thereof or on the application of
any receiver or receivers appointed for the corporation under the provisions of
Section 291 of Title 8 of the Delaware Code or on the application of trustees in
dissolution or of any receiver or receivers appointed for the corporation under
the provisions of Section 279 of Title 8 of the Delaware Code order a meeting of
the creditors or class of creditors, and/or of the stockholders or class of
stockholders of the corporation, as the case may be, to be summoned in such
manner as the said court directs. If a majority in number representing
three-fourths in value of the creditors or class of creditors, and/or of the
stockholders or class of stockholders of the corporation, as the case may be,
agree to any compromise or arrangement and to any reorganization of the
corporation as a consequence of such compromise or arrangement, the said
compromise or arrangement and the said reorganization shall, if sanctioned by
the court to which the said application has been made, be binding on all the
creditors or class of creditors, and/or on all the stockholders or class of
stockholders, of the corporation, as the case may be, and also on the
corporation.

Article VIII

        No director of the corporation shall be liable to the corporation or its
stockholders for monetary damages for breach of fiduciary duty as a director,
except for liability (i) for any breach of the director's duty of loyalty to the
corporation or its stockholders, (ii) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law, or (iv) for any transaction
from which the director derived an improper personal benefit.

Article IX

        The corporation shall have the right, subject to any express provisions
or restrictions contained in this certificate of incorporation or bylaws of the
corporation, from time to time, to amend this certificate of incorporation or
any provision hereof in any manner now or hereafter provided by law, and all
rights and powers of any kind conferred upon a director or stockholder of this
corporation by this certificate of incorporation or any amendment hereof are
subject to such right of the corporation.

        IN WITNESS WHEREOF, the Corporation has caused this certificate to be
duly executed this            th day of                        , 20    .

    MarkWest Hydrocarbon, Inc.
 
 
    

--------------------------------------------------------------------------------

Frank M. Semple
President and Chief Executive Officer

C-2

--------------------------------------------------------------------------------

Annex D

BYLAWS

OF

MARKWEST HYDROCARBON, INC.

A Delaware Corporation

Date of Adoption:

                        , 20    

--------------------------------------------------------------------------------

TABLE OF CONTENTS

ARTICLE I
OFFICES
Section 1.1
 
Registered Office
 
2 Section 1.2   Other Offices   2
ARTICLE II
STOCKHOLDERS
Section 2.1
 
Place of Meetings
 
2 Section 2.2   Quorum; Adjournment of Meetings   2 Section 2.3   Annual
Meetings   2 Section 2.4   Special Meetings   2 Section 2.5   Record Date   2
Section 2.6   Notice of Meetings   2 Section 2.7   Stock List   2 Section 2.8  
Proxies   2 Section 2.9   Voting; Elections; Inspectors   2 Section 2.10  
Conduct of Meetings   2 Section 2.11   Treasury Stock   2 Section 2.12   Action
Without Meeting   2
ARTICLE III
BOARD OF DIRECTORS
Section 3.1
 
Power; Number; Term of Office
 
2 Section 3.2   Chairman of the Board   2 Section 3.3   Quorum   2 Section 3.4  
Place of Meetings; Order of Business   2 Section 3.5   First Meeting   2 Section
3.6   Regular Meetings   2 Section 3.7   Special Meetings   2 Section 3.8  
Removal   2 Section 3.9   Vacancies; Increases in the Number of Directors   2
Section 3.10   Compensation   2 Section 3.11   Action Without a Meeting;
Telephone Conference Meeting   2 Section 3.12   Approval or Ratification of Acts
or Contracts by Stockholders   2
ARTICLE IV
COMMITTEES
Section 4.1
 
Designation; Powers
 
2 Section 4.2   Procedure; Meetings; Quorum   2 Section 4.3   Substitution of
Members   2
ARTICLE V
OFFICERS
Section 5.1
 
Number, Titles and Term of Office
 
2 Section 5.2   Salaries   2 Section 5.3   Removal   2 Section 5.4   Vacancies  
2 Section 5.5   President   2          

D-i

--------------------------------------------------------------------------------

Section 5.6   Vice Presidents   2 Section 5.7   Treasurer   2 Section 5.8  
Secretary   2 Section 5.9   Action with Respect to Securities of Other
Corporations   2
ARTICLE VI
INDEMNIFICATION OF DIRECTORS,
OFFICERS, EMPLOYEES AND AGENTS
Section 6.1
 
Right to Indemnification
 
2 Section 6.2   Indemnification of Employees and Agents   2 Section 6.3   Right
of Claimant to Bring Suit   2 Section 6.4   Nonexclusivity of Rights   2 Section
6.5   Insurance   2 Section 6.6   Savings Clause   2 Section 6.7   Amendment,
Modification or Repeal.   2
ARTICLE VII
CAPITAL STOCK
Section 7.1
 
Certificates of Stock
 
2 Section 7.2   Transfer of Shares   2 Section 7.3   Ownership of Shares   2
Section 7.4   Regulations Regarding Certificates   2 Section 7.5   Lost or
Destroyed Certificates   2
ARTICLE VIII
MISCELLANEOUS PROVISIONS
Section 8.1
 
Fiscal Year
 
2 Section 8.2   Corporate Seal   2 Section 8.3   Notice and Waiver of Notice   2
Section 8.4   Resignations   2 Section 8.5   Facsimile Signatures   2 Section
8.6   Reliance upon Books, Reports and Records   2
ARTICLE IX
AMENDMENTS
Section 9.1
 
Amendments
 
2

D-ii

--------------------------------------------------------------------------------

BYLAWS
OF
MARKWEST HYDROCARBON, INC.

ARTICLE I
OFFICES

        Section 1.1    Registered Office.    The registered office of MarkWest
Hydrocarbon, Inc. (the "Corporation") required by the General Corporation Law of
the State of Delaware (the "DGCL") to be maintained in the State of Delaware,
shall be the registered office named in the original Certificate of
Incorporation of the Corporation (as the same may be amended and restated from
time to time, the "Certificate of Incorporation"), or such other office as may
be designated from time to time by the Board of Directors in the manner provided
by law. Should the Corporation maintain a principal office within the State of
Delaware such registered office need not be identical to such principal office
of the Corporation.

        Section 1.2    Other Offices.    The Corporation may also have offices
at such other places both within and without the State of Delaware as the Board
of Directors may from time to time determine or the business of the Corporation
may require.

ARTICLE II
STOCKHOLDERS

        Section 2.1    Place of Meetings.    All meetings of the stockholders
shall be held at the principal office of the Corporation, or at such other place
within or without the State of Delaware as shall be specified or fixed in the
notices or waivers of notice thereof.

        Section 2.2    Quorum; Adjournment of Meetings.    Unless otherwise
required by law or provided in the Certificate of Incorporation or these bylaws,
the holders of a majority of the stock issued and outstanding and entitled to
vote thereat, present in person or represented by proxy, shall constitute a
quorum at any meeting of stockholders for the transaction of business and the
act of a majority of such stock so represented at any meeting of stockholders at
which a quorum is present shall constitute the act of the meeting of
stockholders. The stockholders present at a duly organized meeting may continue
to transact business until adjournment, notwithstanding the withdrawal of enough
stockholders to leave less than a quorum.

        Notwithstanding the other provisions of the Certificate of Incorporation
or these bylaws, the chairman of the meeting or the holders of a majority of the
issued and outstanding stock present in person or represented by proxy at any
meeting of stockholders, whether or not a quorum is present, shall have the
power to adjourn such meeting from time to time, without any notice other than
announcement at the meeting of the time and place of the holding of the
adjourned meeting; provided, however, if the adjournment is for more than thirty
(30) days, or if after the adjournment a new record date is fixed for the
adjourned meeting, a notice of the adjourned meeting shall be given to each
stockholder of record entitled to vote at such meeting. At any such adjourned
meeting at which a quorum shall be present or represented any business may be
transacted that might have been transacted at the meeting as originally called.

        Section 2.3    Annual Meetings.    An annual meeting of the
stockholders, for the election of directors to succeed those whose terms expire
and for the transaction of such other business as may properly come before the
meeting, shall be held at such place, within or without the State of Delaware,
on such date, and at such time as the Board of Directors shall fix and set forth
in the notice of the

D-1

--------------------------------------------------------------------------------

meeting, which date shall be within thirteen (13) months subsequent to the later
of the date of incorporation of the Corporation or the last annual meeting of
stockholders.

        Section 2.4    Special Meetings.    Unless otherwise provided in the
Certificate of Incorporation, special meetings of the stockholders for any
purpose or purposes may be called at any time by the Chairman of the Board, by
the President or by a majority of the Board of Directors, and shall be called by
the Chairman of the Board, by the President or the Secretary upon the written
request therefor, stating the purpose or purposes of the meeting, delivered to
such officer, signed by the holder(s) of at least twenty five percent (25%) of
the issued and outstanding stock entitled to vote at such meeting.

        Section 2.5    Record Date.    For the purpose of determining
stockholders entitled to notice of or to vote at any meeting of stockholders, or
any adjournment thereof, or entitled to express consent to corporate action in
writing without a meeting, or entitled to receive payment of any dividend or
other distribution or allotment of any rights, or entitled to exercise any
rights in respect of any change, conversion or exchange of stock or for the
purpose of any other lawful action, the Board of Directors of the Corporation
may fix, in advance, a date as the record date for any such determination of
stockholders, which date shall not be more than sixty (60) days nor less than
ten (l0) days before the date of such meeting, nor more than sixty (60) days
prior to any other action.

        If the Board of Directors does not fix a record date for any meeting of
the stockholders, the record date for determining stockholders entitled to
notice of or to vote at such meeting shall be at the close of business on the
day next preceding the day on which notice is given or, if, in accordance with
Section 8.3 of these bylaws notice is waived, at the close of business on the
day next preceding the day on which the meeting is held. If, in accordance with
Section 2.12, corporate action without a meeting of stockholders is to be taken,
the record date for determining stockholders entitled to express consent to such
corporate action in writing, when no prior action by the Board of Directors is
necessary, shall be the day on which the first written consent is expressed. The
record date for determining stockholders for any other purpose shall be at the
close of business on the day on which the Board of Directors adopts the
resolution relating thereto.

        A determination of stockholders of record entitled to notice of or to
vote at a meeting of stockholders shall apply to any adjournment of the meeting;
provided, however, that the Board of Directors may fix a new record date for the
adjourned meeting.

        Section 2.6    Notice of Meetings.    Written notice of the place, date
and hour of all meetings, and, in case of a special meeting, the purpose or
purposes for which the meeting is called, shall be given by or at the direction
of the Chairman of the Board or the President, the Secretary or the other
person(s) calling the meeting to each stockholder entitled to vote thereat not
less than ten (10) nor more than sixty (60) days before the date of the meeting.
Such notice may be delivered personally, by mail or by electronic transmission
pursuant to Section 232 of the DGCL. If mailed, notice is given when deposited
in the United States mail, postage prepaid, directed to the stockholder at his
address as it appears on the records of the Corporation. If electronically
transmitted, notice is given as provided in Section 232 of the DGCL.

        Section 2.7    Stock List.    A complete list of stockholders entitled
to vote at any meeting of stockholders, arranged in alphabetical order for each
class of stock and showing the address of each such stockholder and the number
of shares registered in the name of such stockholder, shall be open to the
examination of any stockholder, for any purpose germane to the meeting, during
ordinary business hours, for a period of at least ten (10) days prior to the
meeting at the Corporation's principal place of business during ordinary
business hours. The stockholder list shall also be produced and kept at the time
and place of the meeting during the whole time thereof, and may be inspected by
any stockholder who is present.

D-2

--------------------------------------------------------------------------------

        Section 2.8    Proxies.    Each stockholder entitled to vote at a
meeting of stockholders or to express consent or dissent to a corporate action
in writing without a meeting may authorize another person or persons to act for
him by proxy. Proxies for use at any meeting of stockholders shall be filed with
the Secretary, or such other officer as the Board of Directors may from time to
time determine by resolution, before or at the time of the meeting. All proxies
shall be received and taken charge of and all ballots shall be received and
canvassed by the secretary of the meeting who shall decide all questions
touching upon the qualification of voters, the validity of the proxies, and the
acceptance or rejection of votes, unless an inspector or inspectors shall have
been appointed by the chairman of the meeting, in which event such inspector or
inspectors shall decide all such questions.

        No proxy shall be valid after three (3) years from its date, unless the
proxy provides for a longer period. Each proxy shall be revocable unless
expressly provided therein to be irrevocable and coupled with an interest
sufficient in law to support an irrevocable power.

        Should a proxy designate two or more persons to act as proxies, unless
such instrument shall provide the contrary, a majority of such persons present
at any meeting at which their powers thereunder are to be exercised shall have
and may exercise all the powers of voting or giving consents thereby conferred,
or if only one be present, then such powers may be exercised by that one; or, if
an even number attend and a majority do not agree on any particular issue, each
proxy so attending shall be entitled to exercise such powers in respect of the
same portion of the shares as he is of the proxies representing such shares.

        Section 2.9    Voting; Elections; Inspectors.    Unless otherwise
required by law or provided in the Certificate of Incorporation, each
stockholder shall have one vote for each share of stock entitled to vote that is
registered in such stockholder's name on the record date for the meeting. Shares
registered in the name of another corporation, domestic or foreign, may be voted
by such officer, agent or proxy as the bylaw (or comparable instrument) of such
corporation may prescribe, or in the absence of such provision, as the board of
directors (or comparable body) of such corporation may determine. Shares
registered in the name of a deceased person may be voted by his executor or
administrator, either in person or by proxy.

        All voting, except as required by the Certificate of Incorporation or
where otherwise required by law, may be by a voice vote; provided, however, that
upon demand therefor by stockholders holding a majority of the issued and
outstanding stock present in person or by proxy at any meeting a stock vote
shall be taken. Every stock vote shall be taken by written ballots, each of
which shall state the name of the stockholder or proxy voting and such other
information as may be required under the procedure established for the meeting.
Unless otherwise provided in the Certificate of Incorporation, all elections of
directors shall be by ballot.

        At any meeting at which a vote is taken by ballots, the chairman of the
meeting may appoint one or more inspectors, each of whom shall subscribe an oath
or affirmation to execute faithfully the duties of inspector at such meeting
with strict impartiality and according to the best of his ability. Such
inspector shall receive the ballots, count the votes and make and sign a
certificate of the result thereof. The chairman of the meeting may appoint any
person to serve as inspector, except no candidate for the office of director
shall be appointed as an inspector.

        Unless otherwise provided in the Certificate of Incorporation,
cumulative voting for the election of directors shall be prohibited.

        Section 2.10    Conduct of Meetings.    The meetings of the stockholders
shall be presided over by the Chairman of the Board, or if he is not present, by
the President, or if neither the Chairman of the Board, nor President is
present, by a chairman elected at the meeting. The Secretary of the Corporation,
if present, shall act as secretary of such meetings, or if such person is not
present, then a secretary shall be appointed by the chairman of the meeting. The
chairman of any meeting of

D-3

--------------------------------------------------------------------------------

stockholders shall determine the order of business and the procedure at the
meeting, including such regulation of the manner of voting and the conduct of
discussion as seem to him in order.

        Section 2.11    Treasury Stock.    The Corporation shall not vote,
directly or indirectly, shares of its own stock owned by it and such shares
shall not be counted for quorum purposes.

        Section 2.12    Action Without Meeting.    Unless otherwise provided in
the Certificate of Incorporation, any action permitted or required by law, the
Certificate of Incorporation or these bylaws to be taken at a meeting of
stockholders, may be taken without a meeting, without prior notice and without a
vote, if a consent in writing, setting forth the action so taken, shall be
signed by the holders of outstanding stock having not less than the minimum
number of votes that would be necessary to authorize or take such action at a
meeting at which all shares entitled to vote thereon were present and voted.
Prompt notice of the taking of the corporate action without a meeting by less
than a unanimous written consent shall be given by the Secretary to those
stockholders who have not consented in writing.

ARTICLE III
BOARD OF DIRECTORS

        Section 3.1    Power; Number; Term of Office.    The business and
affairs of the Corporation shall be managed by or under the direction of the
Board of Directors, and subject to the restrictions imposed by law, the
provision of these bylaws or the Certificate of Incorporation, they may exercise
all the powers of the Corporation.

        The number of directors of the Corporation shall be determined from time
to time by resolution of the Board of Directors, unless the Certificate of
Incorporation fixes the number of directors, in which case a change in the
number of directors shall be made only by amendment of the Certificate of
Incorporation. Each director shall hold office for the term for which he is
elected, and until his successor shall have been elected and qualified or until
his earlier death, resignation or removal.

        Unless otherwise provided in the Certificate of Incorporation, directors
need not be stockholders or residents of the State of Delaware.

        Section 3.2    Chairman of the Board.    The directors may elect one of
their members to be Chairman of the Board of Directors. The Chairman shall be
subject to the control of, and may be removed as Chairman by, the Board of
Directors. The Chairman of the Board shall have such powers and perform such
duties as usually appertain to the office or as may be prescribed by the Board
of Directors.

        Section 3.3    Quorum.    Unless otherwise provided in the Certificate
of Incorporation or these bylaws, a majority of the total number of directors
shall constitute a quorum for the transaction of business at a meeting of the
Board of Directors and the vote of a majority of the directors present at a
meeting at which a quorum is present shall be the act of the Board of Directors.

        Section 3.4    Place of Meetings; Order of Business.    The directors
may hold their meetings and may have an office and keep the books of the
Corporation, except as otherwise provided by law, in such place or places,
within or without the State of Delaware, as the Board of Directors may from time
to time determine by resolution. At all meetings of the Board of Directors
business shall be transacted in such order as shall from time to time be
determined by the Chairman of the Board, or in his absence by the President, or
by resolution of the Board of Directors.

        Section 3.5    First Meeting.    Each newly elected Board of Directors
may hold its first meeting for the purpose of organization and the transaction
of business, if a quorum is present, immediately after and at the same place as
the annual meeting of the stockholders. Notice of such meeting shall not be
required. At the first meeting of the Board of Directors in each year at which a
quorum shall be

D-4

--------------------------------------------------------------------------------

present, held next after the annual meeting of stockholders, the Board of
Directors shall proceed to the election of the officers of the Corporation.

        Section 3.6    Regular Meetings.    Regular meetings of the Board of
Directors shall be held at such times and places as shall be designated from
time to time by resolution of the Board of Directors. Notice of such regular
meetings shall not be required.

        Section 3.7    Special Meetings.    Special meetings of the Board of
Directors may be called by the Chairman of the Board, the President or, on the
written request of any two directors, by the Secretary, in each case on at least
twenty-four (24) hours personal, written, telegraphic, cable, wireless or
electronic notice to each director. Such notice, or any waiver thereof pursuant
to Section 8.3 hereof, need not state the purpose or purposes of such meeting,
except as may otherwise be required by law or provided for in the Certificate of
Incorporation or these bylaws.

        Section 3.8    Removal.    Any director or the entire Board of Directors
may be removed, with or without cause, by the holders of a majority of the
shares then entitled to vote at an election of directors; provided that, unless
the Certificate of Incorporation otherwise provides, if the Board of Directors
is classified, then the stockholders may effect such removal only for cause; and
provided further that, if the Certificate of Incorporation expressly grants to
stockholders the right to cumulate votes for the election of directors and if
less than the entire board is to be removed, no director may be removed without
cause if the votes cast against his removal would be sufficient to elect him if
then cumulatively voted at an election of the entire Board of Directors, or, if
there be classes of directors, at an election of the class of directors of which
such director is a part.

        Section 3.9    Vacancies; Increases in the Number of
Directors.    Unless otherwise provided in the Certificate of Incorporation,
newly created directorships resulting from any increase in the authorized number
of directors and any other vacancy on the Board of Directors may be filled by a
majority of the directors then in office, although less than a quorum, or a sole
remaining director; and any director so chosen shall hold office until the next
annual election and until his successor shall be duly elected and shall qualify,
unless sooner displaced.

        If the directors of the Corporation are divided into classes, any
directors elected to fill vacancies or newly created directorships shall hold
office until the next election of the class for which such directors shall have
been chosen, and until their successors shall be duly elected and shall qualify.

        Section 3.10    Compensation.    Unless otherwise restricted by the
Certificate of Incorporation, the Board of Directors shall have the authority to
fix the compensation of directors.

        Section 3.11    Action Without a Meeting; Telephone Conference
Meeting.    Unless otherwise restricted by the Certificate of Incorporation, any
action required or permitted to be taken at any meeting of the Board of
Directors, or any committee designated by the Board of Directors, may be taken
without a meeting if all members of the Board of Directors or committee, as the
case may be consent thereto in writing, and the writing or writings are filed
with the minutes of proceedings of the Board of Directors or committee. Such
consent shall have the same force and effect as a unanimous vote at a meeting,
and may be stated as such in any document or instrument filed with the Secretary
of State of Delaware.

        Unless otherwise restricted by the Certificate of Incorporation, subject
to the requirement for notice of meetings, members of the Board of Directors, or
members of any committee designated by the Board of Directors, may participate
in a meeting of such Board of Directors or committee, as the case may be, by
means of a conference telephone or similar communications equipment by means of
which all persons participating in the meeting can hear each other, and
participation in such a meeting shall constitute presence in person at such
meeting, except where a person participates in the meeting for the express
purpose of objecting to the transaction of any business on the ground that the
meeting is not lawfully called or convened.

D-5

--------------------------------------------------------------------------------

        Section 3.12    Approval or Ratification of Acts or Contracts by
Stockholders.    The Board of Directors in its discretion may submit any act or
contract for approval or ratification at any annual meeting of the stockholders,
or at any special meeting of the stockholders called for the purpose of
considering any such act or contract, and any act or contract that shall be
approved or be ratified by the vote of the stockholders holding a majority of
the issued and outstanding shares of stock of the Corporation entitled to vote
and present in person or by proxy at such meeting (provided that a quorum is
present), shall be as valid and as binding upon the Corporation and upon all the
stockholders as if it has been approved or ratified by every stockholder of the
Corporation. In addition, any such act or contract may be approved or ratified
by the written consent of stockholders holding a majority of the issued and
outstanding shares of capital stock of the Corporation entitled to vote and such
consent shall be as valid and as binding upon the Corporation and upon all the
stockholders as if it had been approved or ratified by every stockholder of the
Corporation.

ARTICLE IV
COMMITTEES

        Section 4.1    Designation; Powers.    The Board of Directors may, by
resolution passed by a majority of the entire board, designate one or more
committees, including, if they shall so determine, an executive committee, each
such committee to consist of one or more of the directors of the Corporation.
Any such designated committee shall have and may exercise such of the powers and
authority of the Board of Directors in the management of the business and
affairs of the Corporation as may be provided in such resolution, except that no
such committee shall have the power or authority of the Board of Directors in
reference to amending the Certificate of Incorporation, adopting an agreement of
merger or consolidation, recommending to the stockholders the sale, lease or
exchange of all or substantially all of the Corporation's property and assets,
recommending to the stockholders a dissolution of the Corporation or a
revocation of a dissolution of the Corporation, or amending, altering or
repealing the bylaws or adopting new bylaws for the Corporation and, unless such
resolution or the Certificate of Incorporation expressly so provides, no such
committee shall have the power or authority to declare a dividend or to
authorize the issuance of stock. Any such designated committee may authorize the
seal of the Corporation to be affixed to all papers that may require it. In
addition to the above such committee or committees shall have such other powers
and limitations of authority as may be determined from time to time by
resolution adopted by the Board of Directors.

        Section 4.2    Procedure; Meetings; Quorum.    Any committee designated
pursuant to Section 4.1 shall choose its own chairman, shall keep regular
minutes of its proceedings and report the same to the Board of Directors when
requested, shall fix its own rules or procedures, and shall meet at such times
and at such place or places as may be provided by such rules, or by resolution
of such committee or resolution of the Board of Directors. At every meeting of
any such committee, the presence of a majority of all the members thereof shall
constitute a quorum and the affirmative vote of a majority of the members
present shall be necessary for the adoption by it of any resolution.

        Section 4.3    Substitution of Members.    The Board of Directors may
designate one or more directors as alternate members of any committee, who may
replace any absent or disqualified member at any meeting of such committee. In
the absence or disqualification of a member of a committee, the member or
members present at any meeting and not disqualified from voting, whether or not
constituting a quorum, may unanimously appoint another member of the Board of
Directors to act at the meeting in the place of the absent or disqualified
member.

D-6

--------------------------------------------------------------------------------

ARTICLE V
OFFICERS

        Section 5.1    Number, Titles and Term of Office.    The officers of the
Corporation shall be a President and a Secretary and, if the Board of Directors
so elects, one or more Vice Presidents (any one or more of whom may be
designated Executive Vice President or Senior Vice President), a Treasurer and
such other officers as the Board of Directors may from time to time elect or
appoint. Each officer shall hold office until his successor shall be duly
elected and shall qualify or until his death or until he shall resign or shall
have been removed in the manner hereinafter provided. Any number of offices may
be held by the same person. No officer need be a director.

        Section 5.2    Salaries.    The salaries or other compensation of the
officers and agents of the Corporation shall be fixed from time to time by the
Board of Directors.

        Section 5.3    Removal.    Any officer or agent elected or appointed by
the Board of Directors may be removed, either with or without cause, by the vote
of a majority of the whole Board of Directors at a special meeting called for
the purpose, or at any regular meeting of the Board of Directors, provided the
notice for such meeting shall specify that the matter of any such proposed
removal will be considered at the meeting but such removal shall be without
prejudice to the contract rights, if any, of the person so removed. Election or
appointment of an officer or agent shall not of itself create contract rights.

        Section 5.4    Vacancies.    Any vacancy occurring in any office of the
Corporation may be filled by the Board of Directors.

        Section 5.5    President.    The President shall be the chief executive
officer of the Corporation and, shall have all such powers and perform such
duties as usually appertain to the office or as may be prescribed by the Board
of Directors. In the absence of the Chairman of the Board, or in the event of
his inability or refusal to act, the President shall perform the duties and
exercise the powers of the Chairman of the Board. In the absence of the Chairman
of the Board, the President shall preside at all meetings of the stockholders
and (should he be a director) of the Board of Directors. He may also preside at
any such meeting attended by the Chairman of the Board if he is so designated by
the Chairman of the Board.

        Section 5.6    Vice Presidents.    The Board of Directors in its
discretion may elect one or more Vice Presidents (any one or more of whom may be
designated Executive Vice President or Senior Vice President). Each Vice
President shall perform such duties and have such powers as from time to time
may be prescribed by the Board of Directors, the Chairman of the Board or the
President.

        Section 5.7    Treasurer.    The Treasurer, if any, shall have all such
powers and perform such duties as usually appertain to the office or as may be
prescribed by the Board of Directors, the Chairman of the Board or the
President.

        Section 5.8    Secretary.    The Secretary shall have all such powers
and perform such duties as usually appertain to the office or as may be
prescribed by the Board of Directors, the Chairman of the Board or the
President. In the absence of the President, or in the event of the President's
inability or refusal to act, the Secretary shall perform the duties of the
President, and the Secretary when so acting shall have all the powers of and be
subject to all the restrictions upon the President.

        Section 5.9    Action with Respect to Securities of Other
Corporations.    Unless otherwise directed by the Board of Directors, the
President shall have power to vote and otherwise act on behalf of the
Corporation, in person or by proxy, at any meeting of security holders of or
with respect to any action of security holders of any other entity in which this
Corporation may hold securities, and otherwise to exercise any and all rights
and powers which this Corporation may possess by reason of its ownership of such
securities, in each case with respect to any vote, action or exercise of rights
or powers with

D-7

--------------------------------------------------------------------------------

respect to any matter which would have been within the authority of the
President had such vote, action or exercise of rights or powers been taken with
respect to the Corporation. For purposes of this Section, the term "security"
includes any partnership interest, membership interest, units, or other security
owned by the Corporation in an entity, and the term "security holder" includes
partner, member, unit holder, and shareholder in an entity.

ARTICLE VI
INDEMNIFICATION OF DIRECTORS,
OFFICERS, EMPLOYEES AND AGENTS

        Section 6.1    Right to Indemnification.    Each person who was or is
made a party or is threatened to be made a party to or is involved in any
threatened, pending or completed action, suit or proceeding, whether civil,
criminal, administrative or investigative (hereinafter a "proceeding"), by
reason of the fact that such person or a person of whom such person is the legal
representative, is or was or has agreed to become a director or officer of the
Corporation or is or was serving or has agreed to serve at the request of the
Corporation as a director, officer, employee or agent of another corporation or
of a partnership, joint venture, trust or other enterprise, including service
with respect to employee benefit plans, whether the basis of such proceeding is
alleged action in an official capacity as a director or officer or in any other
capacity while serving or having agreed to serve as a director or officer, shall
be indemnified and held harmless by the Corporation to the fullest extent
authorized by the DGCL, as the same exists or may hereafter be amended, (but, in
the case of any such amendment, only to the extent that such amendment permits
the Corporation to provide broader indemnification rights than said law
permitted the Corporation to provide prior to such amendment) against all
expense, liability and loss (including without limitation, attorneys' fees,
judgments, fines, ERISA excise taxes or penalties and amounts paid or to be paid
in settlement) reasonably incurred or suffered by such person in connection
therewith and such indemnification shall continue as to a person who has ceased
to serve in the capacity that initially entitled such person to indemnity
hereunder and shall inure to the benefit of such person's heirs, executors and
administrators; provided, however, that the Corporation shall indemnify any such
person seeking indemnification in connection with a proceeding (or part
thereof), other than a proceeding (or part thereof) brought under Section 6.3,
initiated by such person or such person's heirs, executors and administrators
only if such proceeding (or part thereof) was authorized by the board of
directors of the Corporation.

        The right to indemnification conferred in this Article VI shall be a
contract right and shall include the right to be paid by the Corporation the
expenses incurred in defending any such proceeding in advance of its final
disposition; provided, however, that, if the DGCL requires, the payment of such
expenses incurred by a current, former or proposed director or officer in such
person's capacity as a director or officer or proposed director or officer (and
not in any other capacity in which service was or is or has been agreed to be
rendered by such person while a director or officer, including, without
limitation, service to an employee benefit plan) in advance of the final
disposition of a proceeding, shall be made only upon delivery to the Corporation
of an undertaking, by or on behalf of such indemnified person, to repay all
amounts so advanced if it shall ultimately be determined that such indemnified
person is not entitled to be indemnified under this Section or otherwise.

        Section 6.2    Indemnification of Employees and Agents.    The
Corporation may, by action of its Board of Directors, provide indemnification to
employees and agents of the Corporation, individually or as a group, with the
same scope and effect as the indemnification of directors and officers provided
for in this Article VI.

        Section 6.3    Right of Claimant to Bring Suit.    If a written claim
received by the Corporation from or on behalf of an indemnified party under this
Article VI is not paid in full by the Corporation within ninety (90) days after
such receipt, the claimant may at any time thereafter bring suit against the

D-8

--------------------------------------------------------------------------------

Corporation to recover the unpaid amount of the claim and, if successful in
whole or in part, the claimant shall be entitled to be paid also the expense of
prosecuting such claim. It shall be a defense to any such action (other than an
action brought to enforce a claim for expenses incurred in defending any
proceeding in advance of its final disposition where the required undertaking,
if any is required, has been tendered to the Corporation) that the claimant has
not met the standards of conduct that make it permissible under the DGCL for the
Corporation to indemnify the claimant for the amount claimed, but the burden of
proving such defense shall be on the Corporation. Neither the failure of the
Corporation (including its Board of Directors, independent legal counsel, or its
stockholders) to have made a determination prior to the commencement of such
action that indemnification of the claimant is proper in the circumstances
because such person has met the applicable standard of conduct set forth in the
DGCL, nor an actual determination by the Corporation (including its Board of
Directors, independent legal counsel, or its stockholders) that the claimant has
not met such applicable standard of conduct, shall be a defense to the action or
create a presumption that the claimant has not met the applicable standard of
conduct.

        Section 6.4    Nonexclusivity of Rights.    The right to indemnification
and the advancement and payment of expenses conferred in this Article VI shall
not be exclusive of any other right that any person may have or hereafter
acquire under any law (common or statutory), provision of the Certificate of
Incorporation of the Corporation, bylaw, agreement, vote of stockholders or
disinterested directors or otherwise.

        Section 6.5    Insurance.    The Corporation may maintain insurance, at
its expense, to protect itself and any person who is or was serving as a
director, officer, employee or agent of the Corporation or is or was serving at
the request of the Corporation as a director, officer, employee or agent of
another corporation, partnership, joint venture, trust or other enterprise
against any expense, liability or loss asserted against such person and incurred
by any such person in any such capacity, or arising out of such person's status
as such, whether or not the Corporation would have the power to indemnify such
person against such expense, liability or loss under the DGCL.

        Section 6.6    Savings Clause.    If this Article VI or any portion
hereof shall be invalidated on any ground by any court of competent
jurisdiction, then the Corporation shall nevertheless indemnify and hold
harmless each director and officer of the Corporation, as to costs, charges and
expenses (including attorneys' fees), judgments, fines, and amounts paid in
settlement with respect to any action, suit or proceeding, whether civil,
criminal, administrative or investigative to the full extent permitted by any
applicable portion of this Article VI that shall not have been invalidated and
to the fullest extent permitted by applicable law.

        Section 6.7    Amendment, Modification or Repeal..    Any amendment,
modification or repeal this Article VI by the Board of Directors or the
stockholders of the Corporation shall not adversely affect any right of or
protection afforded to a director, officer, employee or agent of the Corporation
existing at the time of such amendment, modification or repeal.

ARTICLE VII
CAPITAL STOCK

        Section 7.1    Certificates of Stock.    The certificates for shares of
the capital stock of the Corporation shall be in such form, not inconsistent
with that required by law and the Certificate of Incorporation, as shall be
approved by the Board of Directors. The Chairman of the Board, President or a
Vice President shall cause to be issued to each stockholder one or more
certificates, under the seal of the Corporation or a facsimile thereof if the
Board of Directors shall have provided for such seal, and signed by the Chairman
of the Board, President or a Vice President and the Secretary or the Treasurer
or certifying the number of shares (and, if the stock of the Corporation shall
be divided into classes or series, the class and series of such shares) owned by
such stockholder in the Corporation;

D-9

--------------------------------------------------------------------------------

provided, however, that any of or all the signatures on the certificate may be
facsimile. The stock record books and the blank stock certificate books shall be
kept by the Secretary, or at the office of such transfer agent or transfer
agents as the Board of Directors may from time to time by resolution determine.
In case any officer, transfer agent or registrar who shall have signed or whose
facsimile signature or signatures shall have been placed upon any such
certificate or certificates shall have ceased to be such officer, transfer agent
or registrar before such certificate is issued by the Corporation, such
certificate may nevertheless be issued by the Corporation with the same effect
as if such person were such officer, transfer agent or registrar at the date of
issue. The stock certificates shall be consecutively numbered and shall be
entered in the books of the Corporation as they are issued and shall exhibit the
holder's name and number of shares.

        Section 7.2    Transfer of Shares.    The shares of stock of the
Corporation shall be transferable only on the books of the Corporation by the
holders thereof in person or by their duly authorized attorneys or legal
representatives upon surrender and cancellation of certificates for a like
number of shares. Upon surrender to the Corporation or a transfer agent of the
Corporation of a certificate for shares duly endorsed or accompanied by proper
evidence of succession, assignment or authority to transfer, it shall be the
duty of the Corporation to issue a new certificate to the person entitled
thereto, cancel the old certificate and record the transaction upon its books.

        Section 7.3    Ownership of Shares.    The Corporation shall be entitled
to treat the holder of record of any share or shares of capital stock of the
Corporation as the holder in fact thereof and, accordingly, shall not be bound
to recognize any equitable or other claim to or interest in such share or shares
on the part of any other person, whether or not it shall have express or other
notice thereof, except as otherwise provided by the laws of the State of
Delaware.

        Section 7.4    Regulations Regarding Certificates.    The Board of
Directors shall have the power and authority to make all such rules and
regulations as they may deem expedient concerning the issue, transfer and
registration or the replacement of certificates for shares of capital stock of
the Corporation.

        Section 7.5    Lost or Destroyed Certificates.    The Board of Directors
may determine the conditions upon which a new certificate of stock may be issued
in place of a certificate which is alleged to have been lost, stolen or
destroyed; and may, in their discretion, require the owner of such certificate
or his legal representative to give bond, with sufficient surety, to indemnify
the Corporation and each transfer agent and registrar against any and all losses
or claims which may arise by reason of the issue of a new certificate in the
place of the one so lost, stolen or destroyed.

ARTICLE VIII
MISCELLANEOUS PROVISIONS

        Section 8.1    Fiscal Year.    The fiscal year of the Corporation shall
be a calendar year unless the Board of Directors may establish from time to
time.

        Section 8.2    Corporate Seal.    The Board of Directors may provide a
suitable seal, containing the name of the Corporation. The Secretary shall have
charge of the seal (if any). If and when so directed by the Board of Directors
or a committee thereof, duplicates of the seal may be kept and used by the
Treasurer or by the Secretary.

        Section 8.3    Notice and Waiver of Notice.    Except as otherwise
provided in the bylaws, whenever any notice is required to be given by law, the
Certificate of Incorporation or under the provisions of these bylaws, said
notice shall be deemed to be sufficient if given (i) by telegraphic, cable,
wireless or electronic transmission or (ii) by deposit of the same in a post
office box postage paid in a sealed prepaid wrapper addressed to the person
entitled thereto at his post office address, as it appears on the

D-10

--------------------------------------------------------------------------------

records of the Corporation, and such notice shall be deemed to have been given
on the day of such transmission or mailing, as the case may be.

        Whenever notice is required to be given by law, the Certificate of
Incorporation or under any of the provisions of these bylaws, a written waiver
thereof, signed by the person entitled to notice, whether before or after the
time stated therein, shall be deemed equivalent to notice. Attendance of a
person at a meeting shall constitute a waiver of notice of such meeting, except
when the person attends a meeting for the express purpose of objecting, at the
beginning of the meeting, to the transaction of any business because the meeting
is not lawfully called or convened. Neither the business to be transacted at,
nor the purpose of, any regular or special meeting of the stockholders,
directors, or members of a committee of directors need be specified in any
written waiver of notice unless so required by the Certificate of Incorporation
or the bylaws.

        Section 8.4    Resignations.    Any director, member of a committee or
officer may resign at any time. Such resignation shall be made in writing and
shall take effect at the time specified therein, or if no time be specified, at
the time of its receipt by the President or Secretary. The acceptance of a
resignation shall not be necessary to make it effective, unless expressly so
provided in the resignation.

        Section 8.5    Facsimile Signatures.    In addition to the provisions
for the use of facsimile signatures elsewhere specifically authorized in these
bylaws, facsimile signatures of any officer or officers of the Corporation may
be used whenever and as authorized by the Board of Directors.

        Section 8.6    Reliance upon Books, Reports and Records.    Each
director and each member of any committee designated by the Board of Directors
shall, in the performance of such director's or member's duties, be fully
protected in relying in good faith upon the books of account or reports made to
the Corporation by any of its officers, or by an independent certified public
accountant, or by an appraiser selected with reasonable care by the Board of
Directors or by any such committee, or in relying in good faith upon other
records of the Corporation.

ARTICLE IX
AMENDMENTS

        Section 9.1    Amendments.    If provided in the Certificate of
Incorporation of the Corporation, the Board of Directors shall have the power to
adopt, amend and repeal from time to time bylaws of the Corporation, subject to
the right of the stockholders entitled to vote with respect thereto to amend or
repeal such bylaws as adopted or amended by the Board of Directors.

D-11

--------------------------------------------------------------------------------

Annex E

CONFIDENTIALITY AGREEMENT

                        , 2007

 
 
  

Ladies and Gentlemen:

        We understand that                        ("you") may be interested in
considering a possible negotiated transaction involving a business combination
with MarkWest Hydrocarbon, Inc. (together with its affiliated companies, the
"Company"). In connection with your interest in a possible negotiated
transaction involving a business combination with the Company (any such possible
transaction being referred to herein as a "Transaction"), we propose to furnish
you with certain confidential information related to the Company. As a condition
to your receipt of such Confidential Information (as hereinafter defined), you
agree to treat the Confidential Information and any other information concerning
a Transaction or the Company which is furnished to you or your Representatives
(as defined below) by or on behalf of the Company in accordance with the
provisions of this Confidentiality Agreement (this "Agreement") and to take or
refrain from taking certain other actions herein set forth.

1.You recognize and acknowledge the competitive value and confidential nature of
the Confidential Information and the damage that would result to the Company if
any of the Confidential Information is disclosed to any third party in violation
of this Agreement. You hereby agree that the Confidential Information will be
used solely for the purposes of evaluating a Transaction and that all of the
Confidential Information will be kept confidential by you and your
Representatives; provided that any such information may be disclosed only to
your Representatives who need to know the Confidential Information because they
are working on or consulted in connection with evaluating a Transaction and
shall not be used for any purpose other than for the purposes of evaluating a
Transaction. "Representatives" means, collectively, and with respect to a person
or entity, the partners, officers, directors, employees and affiliates (and
employees of such affiliates), agents, financial, legal or accounting or other
advisors or other representatives of such person or entity. You represent that
each of your Representatives is formally apprised of his or her obligations
concerning the confidentiality of all client affairs and information and will be
apprised of his or her obligations hereunder prior to disclosure of any
Confidential Information. You agree that you shall be responsible for any breach
of this Agreement by any of your Representatives.

2.The term "Confidential Information" includes (i) all information furnished by
or on behalf of the Company or any of its Representatives, whether furnished
before or after the date hereof, whether oral or written, and regardless of the
manner in which it is furnished, (ii) all analyses, compilations, forecasts,
studies, interpretations or other documents prepared by you or your
Representatives in connection with your evaluation of a Transaction (including,
without limitation, such that reflects or is based upon, in whole or part, the
information furnished to you or your Representatives pursuant hereto)
(collectively, "Notes"), and (iii) the fact that (a) information has been
furnished to you or your Representatives, (b) you are considering a possible
Transaction involving the Company and (c) discussions or negotiations are taking
place concerning a possible Transaction, and any of the terms, conditions or
other facts with respect to any such possible Transaction, including the status
thereof. The term "Confidential Information" does not include any information
that (i) at the time of disclosure or thereafter is generally available to or
known by the public (other than as a result of its disclosure by you or your
Representatives in breach of this Agreement), or (ii) becomes available to you
from a person who is not known by you to be

E-1

--------------------------------------------------------------------------------

prohibited from transmitting the information to you by an obligation of secrecy
to the Company. As used in this Agreement, the term "person" shall be broadly
interpreted to include, without limitation, any individual, partnership,
corporation, trust, limited liability company, or other entity.

3.Given the nature of the Confidential Information, the Company and its
Representatives may be irreparably damaged by any unauthorized disclosure of any
Confidential Information or by any breach of this Agreement by you or your
Representatives. Without prejudice to the rights and remedies otherwise
available to the Company, you, therefore, agree that the Company shall be
entitled to seek equitable relief, including an injunction or specific
performance, in the event of any breach of the provisions of this Agreement by
you or your Representatives. Such remedies shall not be deemed to be exclusive
remedies but shall be in addition to all other remedies available at law or
equity to the Company. In the event of litigation relating to this Agreement, if
a court of competent jurisdiction determines in a final, non-appealable order
that you or any of your Representatives have breached this Agreement, then you
shall be liable and pay to the Company the costs and expenses (including
attorney's fees) as awarded by that competent court that result as a consequence
of you not meeting the terms of this Agreement.

4.All of the Confidential Information shall remain the property of the Company.
Within 15 days of any request by the Company or its Representative, you agree to
(i) destroy, except to the extent that you have been advised in writing by
outside counsel that such destruction is prohibited by law, or redeliver to the
person making the request all Confidential Information in printed format or
compact disc/dvd and delete from the emails and directories of your and your
Representative's computers Confidential Information transmitted by the Company
or its Representatives in electronic format and (ii) destroy all Notes and other
materials prepared by you or your Representatives based upon, containing or
otherwise reflecting the Confidential Information. Notwithstanding the above,
you and your Representatives (i) may retain Confidential Information in
accordance with your internal compliance procedures or to the extent any of such
information is relevant to demonstrate compliance by you or your Representatives
with any legal, regulatory, professional or fiduciary obligation, and (ii) shall
only be required to use commercially reasonable efforts to destroy Confidential
Information that is stored electronically; provided that such Confidential
Information that is not returned or destroyed (including oral information) shall
remain subject to this Agreement.

5.Without the prior written consent of the Company, for a period of one year
from the date of this Agreement, you will not, and will cause your affiliates
not to, and will not encourage or assist others, directly or indirectly, to:
(i) acquire, offer or propose (whether publicly or otherwise) to acquire, or
agree or seek to acquire, by purchase or otherwise, any securities or direct or
indirect rights or options to acquire any securities of the Company or its
subsidiaries with the intent or effect of acquiring a controlling interest in
the Company or its subsidiaries or of any successor to or person in control of
the Company or any of its subsidiaries, or any assets of the Company or its
subsidiaries or divisions thereof or of any such successor or controlling
person, (ii) enter into or agree, offer, propose or seek to enter into, or
otherwise be involved in or part of, any acquisition transaction or other
business combination relating to all or part of the Company or its subsidiaries
or any acquisition transaction for all or part of the assets of the Company or
its subsidiaries or any of their respective businesses; (iii) make, or in any
way participate in, any "solicitation" of "proxies" (as such terms are used in
the rules of the Securities and Exchange Commission) to vote, or seek to advise
or influence any person or entity with respect to the voting of, or to provide
or withhold consents with respect to any voting securities of the Company or any
of its subsidiaries; (iv) form, join or in any way participate in a "group"
(within the meaning of Section 13(d)(3) of the Securities Exchange Act of 1934)
either with respect to any voting securities of the Company or any of its
subsidiaries or in connection with any of the types of matters set forth in
(i) through (iii) above; (v) seek or propose, alone or in concert with others,
to

E-2

--------------------------------------------------------------------------------

influence or control the Company's management, Board of Directors or policies of
the Company or any of its subsidiaries; (vi) enter into any discussions,
negotiations, arrangements or understandings with any other Person with respect
to any of the foregoing activities or propose any of such activities to any
other Person; (vii) advise, assist, encourage, act as a financing source for or
otherwise invest in any other person in connection any of the foregoing
activities; or (viii) disclose any intention, plan or arrangement inconsistent
with any of the foregoing. You will promptly advise the Company of any inquiry
or proposal made to you with respect to any of the foregoing. You also agree
that, during, the one-year period from the date of this Agreement, neither you
or any of your affiliates will: (i) request the Company or its advisors,
directly or indirectly, to (A) amend or waive any provision of this paragraph
(including this sentence) or (B) otherwise consent to any action inconsistent
with any provision of this paragraph (including this sentence); or (ii) take any
initiative with respect to the Company or any of its subsidiaries which could
require the Company to make a public announcement regarding (A) such initiative,
(B) any of the activities referred to in the second preceding sentence, (C) the
possibility of a Transaction or (D) the possibility of you or any other person
acquiring, control of the Company, whether by means of a business combination or
otherwise. Notwithstanding the foregoing, if an unaffiliated third party seeks
to acquire or assists, advises or encourages any other persons in seeking to
acquire, directly or indirectly, control of the Company or any of the Company's
securities, businesses or assets without the consent of the Company's board of
directors during the one-year period from the date of this Agreement, then you
will be permitted hereunder to take any of the foregoing actions.

6.For a period of one year from the date of this Agreement, you shall not, and
you shall cause your affiliates not to, directly or indirectly, solicit for
employment or hire any employee of the Company or any of its subsidiaries with
whom you have had contact or who became known to you in connection with your
evaluation of a Transaction; provided that it will not be a breach of the
foregoing provision if you (i) make solicitations for employment by general
advertisements in periodicals of broad distribution or other advertisement media
of similar nature or through the use of search firms that are not directed
specifically at executives or employees of the Company or (ii) hire any person
that responds to a solicitation of the type described in clause (i) if such
party has not otherwise solicited such person

7.You understand and acknowledge that neither the Company nor any of its
Representatives makes any representation or warranty, express or implied, as to
the accuracy or completeness of the Confidential Information. Other than as set
forth in a definitive transaction agreement, you agree that neither the Company
nor any of its Representatives shall have any liability to you or any of your
Representatives relating to or resulting from your or their use of the
Confidential Information or any errors therein or omissions therefrom.

8.In the event that the you or your Representatives are requested or required by
law, regulation (including the rules or regulations of any securities exchange
on which such party's securities are listed for trading), regulatory authority
or other applicable judicial or governmental order to disclose any Confidential
Information, you shall immediately upon learning of such request or requirement,
notify the Company in writing of such request or requirement so that the Company
may seek an appropriate protective order or other appropriate remedy (and if the
Company seeks such an order or remedy, you will provide such cooperation, at the
Company's expense, as the Company shall reasonably request). If no such
protective order or other remedy is obtained and you or your Representatives
are, upon the advice of outside counsel, legally compelled to disclose the
Confidential Information, you or your Representatives, as the case may be, shall
only disclose that portion of the Confidential Information that your or their
outside counsel advises that you or they are compelled to disclose and will
exercise reasonable efforts to obtain assurance that confidential treatment will
be accorded to that portion of the Confidential Information that is

E-3

--------------------------------------------------------------------------------

being disclosed. In any event, you will not oppose action by the Company to
obtain an appropriate protective order or other reliable assurance that
confidential treatment will be accorded the Confidential Information. Any
disclosure of Confidential Information pursuant to and in accordance with this
Section 8 shall not constitute a breach of this Agreement.

9.You agree that, unless and until a binding agreement is entered into with
respect to a Transaction, neither the Company nor you will be under any legal
obligation of any kind whatsoever with respect to a Transaction by virtue of
this or any other written or oral expression, except with respect to the matters
specifically agreed to herein. Except for the matters set forth in this
Agreement or in any such binding agreement, no party shall be entitled to rely
on any statement, promise, agreement or understanding, whether oral or written,
any custom, usage of trade, course of dealing or conduct.

10.You hereby acknowledge that you are aware and that you will advise your
Representatives that the United States federal and state securities laws
prohibit any person or entity who has material, non-public information about a
company from purchasing or selling securities of such a company or from
communicating such information to any other person or entity under circumstances
in which it is reasonably foreseeable that such person or entity is likely to
purchase or sell such securities.

11.This Agreement shall be governed and construed in accordance with the laws of
the State of Colorado without regard to conflict of laws principles. Any action
brought in connection with this Agreement may be brought in the federal or state
courts located in the City of Denver, Colorado, and the parties hereto hereby
irrevocably consent to the jurisdiction of such courts.

12.The provisions of this Agreement shall be binding solely upon and inure to
the benefit of the parties hereto and their respective successors and assigns.

13.This Agreement represents the entire understanding and agreement of the
parties hereto and may be modified only by a separate written agreement executed
by the parties hereto expressly modifying this Agreement. This Agreement
supersedes and cancels any and all prior agreements between the parties hereto,
express or implied, relating to a Transaction.

14.This Agreement may be executed in any number of counterparts, each of which
when so executed shall be deemed an original, but such counterparts shall
together constitute one and the same Agreement.

15.In the event that any provision or portion of this Agreement is determined to
be invalid or unenforceable for any reason, in whole or in part, the remaining
provisions of this Agreement shall be unaffected thereby and shall remain in
full force and effect to the fullest extent permitted by law.

16.The failure or refusal of any party hereto to insist upon strict performance
of any provision of this Agreement or to exercise any right in any one or more
instances or circumstances shall not be construed as a waiver or relinquishment
of such provision or right, nor shall such failures or refusals be deemed a
custom or practice contrary to such provision or right.

17.Unless otherwise stated herein, this Agreement shall terminate on the date
that is two (2) years after the date hereof; provided, however, that termination
of this Agreement will not in any manner terminate the obligations of the
parties under any applicable trade secret laws, and any Confidential Information
that is also trade secrets will be entitled to the full benefits and protections
of such laws.

E-4

--------------------------------------------------------------------------------

        Please confirm your agreement with the foregoing by signing and
returning to the undersigned a duplicate copy of this Agreement.

    Sincerely,
 
 
MarkWest Hydrocarbon, Inc.
 
 
By:
       

--------------------------------------------------------------------------------

Name:
Title:

ACCEPTED AS OF THE DATE FIRST
WRITTEN ABOVE:

([                        ])

        Date:

E-5

--------------------------------------------------------------------------------

QuickLinks

TABLE OF CONTENTS
ANNEXES
DISCLOSURE SCHEDULES
AGREEMENT AND PLAN OF REDEMPTION AND MERGER
WITNESSETH
ARTICLE I CERTAIN DEFINITIONS
ARTICLE II THE REDEMPTION AND MERGER; EFFECTS OF THE MERGER
ARTICLE III REDEMPTION AND MERGER CONSIDERATION; EXCHANGE PROCEDURES
ARTICLE IV ACTIONS PENDING MERGER
ARTICLE V REPRESENTATIONS AND WARRANTIES
ARTICLE VI COVENANTS
ARTICLE VII CONDITIONS TO CONSUMMATION OF THE REDEMPTION AND MERGER
ARTICLE VIII TERMINATION
ARTICLE IX MISCELLANEOUS
THIRD AMENDED AND RESTATED AGREEMENT OF LIMITED PARTNERSHIP OF MARKWEST ENERGY
PARTNERS, L.P.
TABLE OF CONTENTS
ARTICLE II ORGANIZATION
ARTICLE III RIGHTS OF LIMITED PARTNERS
ARTICLE IV CERTIFICATES; RECORD HOLDERS; TRANSFER OF PARTNERSHIP INTERESTS;
REDEMPTION OF PARTNERSHIP INTERESTS
ARTICLE VII MANAGEMENT AND OPERATION OF BUSINESS
APPLICATION FOR TRANSFER OF COMMON UNITS
BYLAWS OF MARKWEST HYDROCARBON, INC.
CONFIDENTIALITY AGREEMENT , 2007