SUBORDINATED PROMISSORY NOTE
THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY APPLICABLE STATE SECURITIES LAWS, AND MAY NOT BE OFFERED OR SOLD
UNLESS IT HAS BEEN REGISTERED UNDER SUCH ACT AND APPLICABLE STATE SECURITIES
LAWS OR UNLESS AN EXEMPTION FROM REGISTRATION IS AVAILABLE AND THEN ONLY IN
COMPLIANCE WITH THE RESTRICTIONS ON TRANSFER SET FORTH HEREIN.
THIS INSTRUMENT AND THE RIGHTS AND OBLIGATIONS EVIDENCED HEREBY ARE SUBORDINATE
IN THE MANNER AND TO THE EXTENT SET FORTH HEREIN TO THE SENIOR DEBT (AS
HEREINAFTER DEFINED); AND EACH HOLDER OF THIS INSTRUMENT, BY ITS ACCEPTANCE
HEREOF, IRREVOCABLY AGREES TO BE BOUND BY THE SUBORDINATION PROVISIONS HEREIN.

$50,000,000   August 10, 2007

     FOR VALUE RECEIVED, QUICKSILVER GAS SERVICES LP, a Delaware limited
partnership (“Payor”), HEREBY AGREES TO PAY to the order of QUICKSILVER
RESOURCES INC., a Delaware corporation, or its successors and assigns (together
with its successors and assigns, the “Subordinated Creditor”), in lawful
currency of the United States of America, in immediately available funds, at
such location or bank account as the Subordinated Creditor shall from time to
time designate, the principal amount of Fifty Million and 00/100 Dollars
($50,000,000), together with interest, compounded quarterly, on the unpaid
principal balance outstanding from time to time from the date hereof until the
Maturity Date (as hereinafter defined) at a rate of interest per annum equal to
the lesser of (a) the Note Rate (as hereinafter defined) or (b) the Highest
Lawful Rate (as hereinafter defined); provided, however, that, notwithstanding
the foregoing, in the event the Payor fails to make any payment of any portion
of the principal of this Note when due and payable (including, without
limitation, due to a Blockage Event), at the request of the Subordinated
Creditor, interest on such overdue amount (including, without limitation,
interest with respect to such overdue amount to the extent permitted by
applicable law) shall accrue at a rate of interest per annum equal to the lesser
of (a) the Note Rate plus two percent (2.00%) and (b) the Highest Lawful Rate.
Capitalized terms used in this Subordinated Promissory Note (this “Note”), but
not defined herein shall have the meanings specified therefor in the Credit
Agreement, dated as of August 10, 2007 (as amended, restated, supplemented or
otherwise modified from time to time, the “Credit Agreement”), among Payor, as
the borrower, the Lenders party thereto, Bank of America, N.A., as L/C Issuer
thereunder, Bank of America, N.A., as Administrative Agent (or any successor
administrative agent appointed pursuant to Article IX of the Credit Agreement,
the “Administrative Agent”) for the Lenders thereunder, and the other Agents
party thereto.
     1. Principal. Subject to the subordination provisions contained in Section
7 hereof, Payor promises to pay the principal on this Note in equal consecutive
quarterly installments of $275,000 on the last Business Day of each calendar
quarter, beginning on March 31, 2008, and to pay the entire remaining
outstanding principal balance on this Note on February 10, 2013 (the

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“Maturity Date”); provided, that, if the final maturity date of the Senior Debt
(as hereinafter defined) is extended to any date later than August 10, 2012
(such later date being referred to herein as the “Extended Senior Maturity
Date”), the Maturity Date shall be automatically extended without further action
by Payor or the Subordinated Creditor to the date that is six months after such
Extended Senior Maturity Date, and the amount of the quarterly installments of
principal will be reamortized to create equal quarterly installments of the
remaining outstanding principal balance on this Note over the remaining term of
this Note as extended. Notwithstanding anything to the contrary herein, any
amounts paid or prepaid hereunder may not be reborrowed thereafter. Furthermore,
notwithstanding anything to the contrary herein, all amounts payable pursuant to
this Note (including, without limitation, all principal and interest payments,
and prepayments thereof) may, at the request of the Subordinated Creditor, be
paid, in whole or in part, using Equity Interests of Payor.
     2. Interest. Subject to the subordination provisions contained in Section 7
hereof, Payor also promises to pay interest on the unpaid principal amount from
time to time outstanding hereunder from the date hereof until such principal
amount is paid in full at the applicable rate per annum set forth above, which
interest shall be payable quarterly on the last Business Day of each calendar
quarter, beginning March 31, 2008, and on the Maturity Date, (a) by capitalizing
the accrued and unpaid interest on this Note and adding it to the then unpaid
principal amount hereof, or (b) at the request of the Subordinated Creditor, by
wire transfer of immediately available funds, in lawful currency of the United
States of America, to a bank account designated by the Subordinated Creditor to
Payor on or prior to the applicable due date therefor. Interest on this Note
will be calculated based on a 360-day year and paid for the actual number of
days elapsed.
     As used herein, the term “Note Rate” shall mean a rate of interest per
annum equal to the Adjusted Eurodollar Rate for an Interest Period of three
(3) months, plus the Applicable Rate for Eurodollar Loans for such day as
determined pursuant to the terms of the Credit Agreement, regardless of whether
such interest rate is in effect for any Borrowings outstanding under the Credit
Agreement, plus one percent (1.00%). The Note Rate shall change effective upon
each change in the Applicable Rate under the Credit Agreement and shall remain
in effect until the next change in the Applicable Rate effected pursuant to the
Credit Agreement. Each determination by the Subordinated Creditor of the Note
Rate shall, except in cases of manifest error, be final, conclusive and binding.
If the Subordinated Creditor determines (which determination shall be conclusive
absent manifest error) that adequate and reasonable means do not exist for
ascertaining the Adjusted Eurodollar Rate or the Eurodollar Rate, as applicable,
pursuant to the terms of the Credit Agreement, for the Interest Period specified
above, then, at the option of the Subordinated Creditor, and in the Subordinated
Creditor’s sole discretion, the Note Rate shall be determined by the
Subordinated Creditor by reference to (a) the Adjusted Eurodollar Rate for such
other Interest Period as the Subordinated Creditor may select in its sole
discretion, or (b) the interest rate applicable to ABR Loans as provided in the
Credit Agreement, in each case, plus the Applicable Rate for such Type of Loan
     3. Prepayments. Subject to the subordination provisions contained in
Section 7 hereof, this Note may be prepaid in full or in part at any time and
from time to time without premium or penalty. The prepayment of any principal
amount of this Note shall be made together with all accrued and unpaid interest
thereon through the date of prepayment and all

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accrued and unpaid costs and expenses then payable hereunder. In the event of a
partial prepayment, the Subordinated Creditor shall record the date and amount
of any such prepayments on the reverse side of this Note, and interest shall
cease to accrue on such prepaid principal amounts.
     4. Note Events of Default.
          (a) The occurrence of any of the following events constitutes an event
of default under this Note (each, a “Note Event of Default”):

                (i) Payor defaults in the payment of any portion of the
principal of, interest on, or other amounts owing under, this Note when due and
payable, except to the extent a failure to pay is due to a Blockage Event; or  
              (ii) Payor or any other Person (other than the Subordinated
Creditor) fails to perform or observe any other term, covenant or agreement
contained in this Note, and such default shall continue unremedied for a period
of thirty (30) days after the earlier to occur of (A) the date upon which a
Responsible Officer of the General Partner becomes aware of such default and
(B) the date upon which written notice thereof is given to Payor by the
Subordinated Creditor; or                   (iii) an Event of Default (as
defined in the Credit Agreement) shall occur; or                   (iv) any
representation or warranty at any time made by Payor or any other Person in this
Note shall be, or shall prove to have been, false or misleading in any material
respect when so made; or                   (v) this Note shall cease, for any
reason, to be in full force and effect; any provision of this Note shall for any
reason cease to be valid and binding on or enforceable against Payor; the
validity or enforceability of this Note is contested by Payor or any other
Person; or Payor denies it has any further liability or obligation under this
Note.

          (b) Subject to the subordination provisions contained in Section 7
hereof, upon the occurrence and during the continuance of any Note Event of
Default, the Subordinated Creditor shall have the right, without notice, demand,
presentment, notice of nonpayment or nonperformance, protest, notice of protest,
notice of intent to accelerate, notice of acceleration or any other notice or
action of any kind, ALL OF WHICH PAYOR HEREBY EXPRESSLY WAIVES AND RELINQUISHES,
(i) by notice to Payor, to declare the entire principal amount then outstanding
on this Note, and all accrued and unpaid interest thereon and all other accrued
and unpaid amounts hereunder, immediately due and payable, whereupon all such
principal, interest and other amounts shall become immediately due and payable,
and the Subordinated Creditor may proceed to enforce the payment of such
principal, interest and other amounts, or part thereof, in such manner as the
Subordinated Creditor may elect and (ii) to exercise all rights and remedies
available to it under this Note or at law or in equity;

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provided, however, subject to the terms hereof, upon the occurrence of any Event
of Default defined in clause (h) or (i) of Article VIII of the Credit Agreement
(in the case of clause (h) of Article VIII of the Credit Agreement, upon the
expiration of the sixty (60) day period mentioned therein), the unpaid principal
amount of this Note, and all accrued and unpaid interest thereon and all other
accrued and unpaid amounts hereunder, shall automatically become due and payable
without further act of the Subordinated Creditor.
     5. Ranking. All obligations evidenced hereby shall (a) be subordinated
pursuant to the subordination provisions contained in Section 7 hereof to the
prior payment in full of the Senior Debt, (b) rank pari passu with all
unsubordinated indebtedness of Payor (other than the Senior Debt), and (c) rank
senior to any subordinated indebtedness of Payor.
     6. Amendment and Restatement. Upon the payment in full of the Senior Debt,
Payor hereby agrees, if requested by the Subordinated Creditor, to execute and
deliver to the Subordinated Creditor a new note that will amend and restate this
Note, which amended and restated note shall, among other things, include those
provisions of the Credit Agreement (including, without limitation, the
applicable provisions for determining the interest rate under the Credit
Agreement, the covenants contained in Articles VI and VII of the Credit
Agreement, the Events of Default (as defined in the Credit Agreement) contained
in Article VIII of the Credit Agreement and the applicable defined terms
contained in the Credit Agreement that are used in such interest rate
provisions, covenants and Events of Default) as the Subordinated Creditor in its
sole discretion shall determine appropriate to include in such amended and
restated note, the provisions of the Credit Agreement so included in such
amended and restated note to include (a) such modifications thereto, in the
Subordinated Creditor’s sole discretion, necessary to conform such provisions
(for example, definitions) for use in the context of such amended and restated
note, and (b) any other changes thereto (including, but not limited to, changing
the methodology for determining the Note Rate) requested by the Subordinated
Creditor and consented to by Payor, such consent not to be unreasonably
withheld, conditioned or delayed.
     7. Subordination Provisions. (a) The aggregate principal amount owing to
the Subordinated Creditor from time to time under this Note, all accrued and
unpaid interest thereon (if any), and any and all other Indebtedness evidenced
by or otherwise owing in respect of this Note, whether now or hereafter
existing, including, without limitation, all such Indebtedness under, or in
respect of, any and all extensions, modifications, substitutions, amendments,
amendments and restatements, renewals, refinancings and refundings of any or all
of the foregoing Indebtedness, and any instrument or agreement evidencing,
governing or otherwise setting forth the terms of any such Indebtedness or other
Indebtedness incurred in any such extension, modification, substitution,
amendment, amendment and restatement, renewal, refinancing or refunding, in each
case whether direct or indirect, absolute or contingent, and whether for
principal, interest (including, without limitation, interest accruing after the
filing of a petition initiating any Insolvency Proceeding (as hereinafter
defined), whether or not such interest accrues after the filing of such petition
for purposes of any applicable Insolvency Laws (as hereinafter defined), or is
an allowed claim in such Insolvency Proceeding), premiums, fees, indemnification
obligations, contract causes of action, costs, expenses or otherwise (all such
Indebtedness being, collectively, the “Subordinated Debt”) is and shall be
subordinate and junior in right of payment, to the extent and in the manner
hereinafter set forth, to the prior payment in full of all Indebtedness, whether
now or hereafter existing, including, without

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limitation, all Lender Indebtedness, under or in respect of: (i) the Credit
Agreement, the Notes, the Security Instruments, the other Loan Documents and the
Hedging Agreements entered into by Payor or any of its Subsidiaries with any
Lender or Secured Affiliate (the “Secured Hedging Agreements”) and (ii) any and
all extensions, modifications, substitutions, amendments, amendments and
restatements, renewals and refundings of any or all of the foregoing
Indebtedness, and any instrument or agreement evidencing, governing or otherwise
setting forth the terms of any such Indebtedness or other Indebtedness incurred
in any such extension, modification, substitution, amendment, amendment and
restatement, renewal or refunding, in each case whether direct or indirect,
absolute or contingent, and whether for principal, interest (including, without
limitation, interest accruing after the filing of a petition initiating any
Insolvency Proceeding, whether or not such interest accrues after the filing of
such petition for purposes of any applicable Insolvency Laws, or is an allowed
claim in such Insolvency Proceeding), premiums, fees, indemnification
obligations (exclusive of indemnification obligations not then owing which
survive the termination or expiration of the Credit Agreement or the other Loan
Documents, to the extent demand therefor has not been made or threatened as of
the date of such termination or expiration), contract causes of action, costs
and expenses pursuant to the Loan Documents (all such Indebtedness being,
collectively, the “Senior Debt”). For all purposes of this Note, the Senior Debt
shall not be deemed to have been paid in full (“paid in full” or “payment in
full”) until (A) such Senior Debt (exclusive of indemnification obligations not
then owing which survive the termination or expiration of the Credit Agreement
or the other Loan Documents, to the extent demand therefor has not been made or
threatened as of the date of such termination or expiration, and Cash
Collateralized L/C Obligations) has been indefeasibly paid in full in cash,
(B) the termination of all of the Commitments, and (C) there are no Letters of
Credit (exclusive of Letters of Credit which have been Cash Collateralized)
issued under the Loan Documents.
          (b) Until all of the Senior Debt shall have been paid in full, subject
to the proviso to this sentence and the last sentence of this Section 7(b), no
payment or distribution of any property or assets of Payor of any kind or
character (including, without limitation, any payment that may be payable in
respect of, or turnover of funds to be applied to, the Subordinated Debt by
reason of any other Indebtedness or obligations of Payor being subordinated to
payment of the Subordinated Debt) shall be made by or on behalf of Payor for or
on account of any Subordinated Debt or any purchase, redemption or other
acquisition thereof (including, without limitation, by way of set-off,
counterclaim or otherwise), and the Subordinated Creditor shall not ask, demand,
sue for, take or receive from Payor, directly or indirectly, in cash or other
property or by set-off or in any other manner (including, without limitation,
from or by way of collateral), payment of all or any of the Subordinated Debt;
provided, however, that notwithstanding the foregoing or anything to the
contrary contained herein or in the Loan Documents, if no Blockage Event then
exists or would result therefrom, Payor (i) may and shall make any and all
regularly scheduled payments in respect of the Subordinated Debt, including any
missed payments (and default interest thereon at the then applicable rate
provided herein) that it was prohibited from making to the Subordinated Creditor
during the existence of any Blockage Event, to the Subordinated Creditor with no
further notice, consent or action by the Administrative Agent, the Lenders or
the Secured Affiliates, and (ii) may make, at any time and from time to time in
whole or in part, any prepayments of this Note to the Subordinated Creditor with
no further notice, consent or action by the Administrative Agent, the Lenders or
the Secured Affiliates. Payor and the Subordinated Creditor (by its acceptance

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hereof) acknowledge and agree that, as of the date of this Note, a Blockage
Event of the type described in clause (C) of the definition thereof exists. As
used herein, the term “Blockage Event” shall mean (A) an Event of Default exists
on the date of any payment on this Note, (B) a judicial proceeding is pending
with respect to any Event of Default on the date of any payment on this Note, or
(C) the Consolidated Leverage Ratio as of the end of the Fiscal Quarter
immediately preceding the date of any principal payment on this Note is equal to
or greater than 3.5 to 1.0 and would be equal to or greater than 3.5 to 1.0
after giving pro forma effect to any such principal payment (in each case as
calculated pursuant to the following sentence). Notwithstanding anything to the
contrary contained in the Credit Agreement, including in the definitions of
Consolidated Leverage Ratio, Consolidated Funded Debt or Funded Indebtedness,
the Consolidated Leverage Ratio for purposes of this Section 7(b) only shall be
calculated to include any Indebtedness remaining on this Note after giving pro
forma effect to any such permitted payment hereunder. Notwithstanding the
foregoing or anything to the contrary contained herein, (1) nothing in this Note
shall prevent the occurrence of any Note Event of Default, the acceleration by
the Subordinated Creditor of any of the indebtedness hereunder after the
acceleration of the Senior Debt or the giving of any notice by the Subordinated
Creditor to Payor with respect thereto, (2) Payor may at all times pay interest
hereunder by capitalization of the accrued and unpaid interest as described in
Section 2 of this Note, and (3) at the request of the Subordinated Creditor,
Payor may at all times make payments or prepayments, in whole or in part, with
respect to this Note using Equity Interests of Payor and/or using the proceeds
from the contemporaneous sale or issuance of Equity Interests of Payor.
          (c) In the event of any dissolution, winding up, liquidation,
arrangement, reorganization, adjustment, protection, relief or composition of
Payor or its debts, whether voluntary or involuntary, in any bankruptcy,
insolvency, arrangement, reorganization, receivership, relief or other similar
action or proceeding under the United States Federal Bankruptcy Code or any
other federal or state bankruptcy or insolvency laws or any similar Governmental
Rule of any other jurisdiction covering the protection of creditors’ rights or
the relief of debtors (collectively, the “Insolvency Laws”) or upon an
assignment for the benefit of creditors or any other marshalling of the
property, assets and liabilities of Payor or otherwise (each, an “Insolvency
Proceeding”), the Administrative Agent, for the ratable benefit of the L/C
Issuer, Lenders and Secured Affiliates (collectively, the “Secured Parties”),
shall be entitled to receive payment in full of all of the Senior Debt (whether
or not any or all of the Senior Debt has been declared due and payable prior to
the date on which such Senior Debt otherwise would have become due and payable)
before the Subordinated Creditor (or anyone claiming through or on its behalf
(including, without limitation, any receiver, trustee or other similar Person)
is entitled to receive or retain any payment or distribution of any kind or
character on account of all or any of the Subordinated Debt, and, to that end,
any payment or distribution of any kind or character (whether in cash, property
or securities) that otherwise would be payable or deliverable upon or with
respect to the Subordinated Debt in any such Insolvency Proceeding (including,
without limitation, any payment that may be payable in respect of, or turnover
of funds to be applied to, the Subordinated Debt by reason of any other
Indebtedness or obligations of Payor being subordinated to payment of the
Subordinated Debt) shall be paid or delivered forthwith directly to the
Administrative Agent, for the account of the Secured Parties, in the same form
as so received (with any necessary endorsement or assignment) for application
(in the case of cash) to, or to be held as collateral (in the case of noncash
property or securities) for, the payment,

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prepayment and/or cash collateralization of the Senior Debt until all of the
Senior Debt shall have been paid in full.
          (d) So long as the Senior Debt shall not have been paid in full, the
Subordinated Creditor shall not (i) ask, demand, sue for, take or receive from
Payor, directly or indirectly, in cash or other property or by set-off or in any
manner (including, without limitation, from or by way of collateral), payment of
all or any of the Subordinated Debt, except such payments as otherwise expressly
permitted herein when no Blockage Event has occurred and is continuing,
(ii) commence, or join with any creditor other than the Administrative Agent in
commencing, or directly or indirectly cause Payor to commence, or assist Payor
in commencing, any Insolvency Proceeding, or (iii) request or accept any
collateral or other security for all or any portion of the Subordinated Debt. If
the Subordinated Creditor, in contravention hereof, shall commence, prosecute or
participate in any of the actions, suits or proceedings referred to above in
this paragraph, then the Administrative Agent may intervene and interpose as a
defense or plea the terms of this Note in its own name or in the name of the
Subordinated Creditor.
          (e) Until such time as all of the Senior Debt has been paid in full,
if any Insolvency Proceeding is commenced by or against Payor, the Subordinated
Creditor authorizes and empowers the Administrative Agent to file proofs of
claim of the Subordinated Debt on behalf of the Subordinated Creditor in any
statutory or non-statutory proceeding as the agent and attorney-in-fact for the
Subordinated Creditor if the Subordinated Creditor fails to file such proofs of
claim on or before the date that is ten (10) days prior to the date such proofs
of claim must be filed by the Subordinated Creditor in accordance with
applicable law; provided, however, that (i) the foregoing authorization and
empowerment (A) imposes no obligation on the Administrative Agent to take any
such action, and (B) is granted only for the specific and limited purpose for
which it is given, and (ii) the Administrative Agent shall have, prior to taking
any such action, given 15 days prior written notice (which notice may be given
up to 60 days prior to the expiration of the time to file such claim) to the
Subordinated Creditor that it intends to file such claim or proof of debt.
Notwithstanding anything to the contrary herein, in no event may the
Administrative Agent, any Lender or any Secured Affiliate vote or take any other
action related to any claim with respect to the Subordinated Debt on behalf of
the Subordinated Creditor, and such agency and appointment of attorney-in-fact
shall not extend to any such right to vote or take any other action related to
any such claim of the Subordinated Creditor, which rights to vote and take
action the Subordinated Creditor is hereby authorized to exercise and take.
          (f) All payments or distributions upon or with respect to the
Subordinated Debt that are received by the Subordinated Creditor contrary to the
provisions of this Note shall be received in trust for the benefit of the
Administrative Agent, shall be segregated from other property or funds of the
Subordinated Creditor and shall be paid or delivered forthwith directly to the
Administrative Agent, for the account of the Secured Parties, in the same form
as so received (with any necessary endorsement or assignment), to be applied (in
the case of cash) to, or held as collateral (in the case of noncash property or
securities) for, the payment, prepayment and/or cash collateralization of the
Senior Debt until all of the Senior Debt shall have been paid in full.
          (g) To the extent that Payor, the Subordinated Creditor or any of
their respective subsidiaries or any other Credit Party or guarantor of or
provider of collateral for the

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Senior Debt shall make any payment on the Senior Debt that is subsequently
invalidated, declared to be fraudulent or preferential or set aside or is
required to be repaid to a trustee, receiver or any other party under any
applicable Insolvency Law or equitable cause (any such payment being a “Voided
Payment”), then to the extent of such Voided Payment, that portion of the Senior
Debt that had been previously satisfied by such Voided Payment shall be
reinstated and continue in full force and effect as if such Voided Payment had
never been made. To the extent that the Subordinated Creditor shall have
received any payments subsequent to the date of the initial receipt of such
Voided Payment by the Administrative Agent or any of the Secured Parties and
such payments have not been invalidated, declared to be fraudulent or
preferential or set aside or required to be repaid to a trustee, receiver or any
other party under any applicable Insolvency Law or equitable cause, the
Subordinated Creditor shall be obligated and hereby agrees that any such payment
so made or received shall be deemed to have been received in trust for the
benefit of the Administrative Agent, and the Subordinated Creditor (by its
acceptance hereof) hereby agrees to pay to the Administrative Agent, upon
demand, the full amount so received by the Subordinated Creditor during such
period of time to the extent necessary to fully restore to the Secured Parties
the amount of such Voided Payment, which amount shall be applied as set forth in
the immediately preceding paragraph.
          (h) The Subordinated Creditor will not:

                (i) (A) cancel or otherwise discharge any of the Subordinated
Debt (except (1) upon payment in full of the Senior Debt, (2) by a conversion of
all or any part of the Subordinated Debt to a capital contribution to Payor in
return for Equity Interests of Payor or (3) as otherwise permitted by the Credit
Agreement), or (B) convert or exchange any of the Subordinated Debt into or for
any other Indebtedness (other than any other Subordinated Debt);        
          (ii) sell, assign, pledge, encumber or otherwise dispose of any of the
Subordinated Debt other than the pledge of the instruments and agreements
evidencing the Subordinated Debt to the Global Administrative Agent (as defined
in the Parent Credit Agreement) pursuant to the Parent Credit Agreement or any
of the other Combined Loan Documents (as defined in the Parent Credit Agreement)
or a transfer or other disposition of such instruments and agreements in
connection with a foreclosure under the Parent Credit Agreement or any of the
other Combined Loan Documents (as defined in the Parent Credit Agreement); or  
                (iii) contest, or cause or encourage any other Person to
contest, at any time, the validity, perfection, priority or enforceability of
the subordination provisions of this Note, the Senior Debt, the agreements
evidencing the Senior Debt or the security interests or the Liens granted to the
Administrative Agent or any of the other Secured Parties pursuant thereto.

          (i) Subject to the payment in full of the Senior Debt, the
Subordinated Creditor shall be subrogated to the rights of the Lenders and the
Secured Affiliates to receive payments or distributions of assets of Payor in
respect of the Senior Debt until the Subordinated Debt shall be paid in full.
For the purposes of such subrogation, payments or distributions to the
Administrative Agent, for the account of the Lenders and the Secured Affiliates,
of any cash,

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property or securities to which the Subordinated Creditor would be entitled
except for the provisions of this Note shall be deemed, as between Payor and its
creditors (other than the Lenders, the Secured Affiliates and the Subordinated
Creditor), to be a payment by Payor to or on account of the Subordinated Debt,
it being understood that the provisions of this Section 7(i) are, and are
intended solely, for the purpose of defining the relative rights of the
Subordinated Creditor, on the one hand, and the Administrative Agent, the
Lenders and the Secured Affiliates, on the other hand.
          (j) The Lenders or other holders of the Senior Debt may, at any time
and from time to time, without any consent of or notice to the Subordinated
Creditor or any other holder of the Subordinated Debt and without impairing or
releasing the obligations of the Subordinated Creditor hereunder:

                (i) change the manner, place or terms of payment of, or change
or extend the time of payment of, or renew payment or change or extend the time
or payment of, or renew or alter, the Senior Debt (including any change in the
rate of interest thereon), or amend, supplement or otherwise modify in any
manner any Loan Document or other instrument, agreement or other document under
which any of the Senior Debt is outstanding;                   (ii) sell,
exchange, release, not perfect and otherwise deal with any of the property or
assets of any Person at any time pledged, assigned or mortgaged to secure the
Senior Debt;                   (iii) release any Person liable in any manner
under or in respect of the Senior Debt;                   (iv) exercise or
refrain from exercising any rights against Payor, any of the other Credit
Parties or any of their respective Subsidiaries or any other Person;        
          (v) apply to the Senior Debt any sums from time to time received by or
on behalf of the Administrative Agent or any of the Secured Parties; or        
          (vi) sell, assign, transfer or exchange any of the Senior Debt.

          (k) Each of Payor and the Subordinated Creditor will, if reasonably
requested by the Administrative Agent, further mark their respective books of
account in such a manner as shall be effective to give proper notice of the
effect of the subordination provisions of this Note. Each of Payor and the
Subordinated Creditor will, at Payor’s sole expense and at any time and from
time to time, promptly execute and deliver all further instruments and
documents, and take all further actions, that may be necessary or that the
Administrative Agent may reasonably deem advisable and may request in order to
protect any right or interest granted or intended to be granted under the
subordination provisions of this Note or to enable the Administrative Agent or
any of the other Secured Parties to exercise and enforce its rights and remedies
hereunder.
          (l) The Subordinated Creditor shall, upon reasonable request from time
to time, from Payor, any Secured Party or any other holder of Senior Debt or any
party who intends to extend Senior Debt to Payor, provide to the holder(s) of
Senior Debt or any such prospective

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holder(s) of Senior Debt a written acknowledgment by the Subordinated Creditor
addressed to such holder(s) of Senior Debt to the effect that such holder of
Senior Debt is a holder of the Senior Debt entitled to the benefits of this
Note, or, in the case of a prospective holder of Senior Debt, to the effect that
the credit to be extended by such prospective holder will be Senior Debt and
that such prospective holder will be entitled to the benefits of this Note.
          (m) Payor acknowledges and agrees that the provisions of this Note,
including, without limitation, the foregoing subordination provisions are, and
are intended to be, an inducement and a consideration to each Secured Party,
whether the Senior Debt held by such Secured Party was created or acquired
before or after the issuance of this Note, to acquire and continue to hold, or
to continue to hold, such Senior Debt and such Secured Party shall be deemed
conclusively to have relied on the provisions of this Note, including, without
limitation, such subordination provisions, in acquiring and continuing to hold,
or in continuing to hold, such Senior Debt.
          (n) The foregoing provisions regarding subordination are and are
intended solely for the purpose of defining the relative rights of the holders
of the Senior Debt, on the one hand, and the holders of the Subordinated Debt,
on the other hand. Such provisions are for the benefit of the holders of the
Senior Debt and shall inure to the benefit of, and shall be enforceable by, the
Administrative Agent, on behalf of itself and the other Secured Parties,
directly against the holders of the Subordinated Debt, and no holder of the
Senior Debt shall be prejudiced in its right to enforce the subordination of any
of the Subordinated Debt by any act or failure to act by Payor or any Person in
custody of its property or assets. The subordination provisions herein shall
constitute a continuing offer to each and every holder of Senior Debt from time
to time and such holders are intended third party beneficiaries hereof. Nothing
contained in the foregoing provisions is intended to or shall impair, as between
Payor and the holders of the Subordinated Debt, the obligations of Payor to such
holders.
     8. WAIVER. PAYOR HEREBY WAIVES PROMPTNESS, DILIGENCE, PRESENTMENT FOR
PAYMENT, DEMAND, NOTICE OF DISHONOR AND PROTEST AND ANY OTHER NOTICE WITH
RESPECT TO THIS NOTE.
     9. Amendments, Etc. None of the provisions of this Note may be waived,
amended, supplemented or otherwise modified except in a writing signed by Payor
and the Subordinated Creditor; provided, however, that, until the Senior Debt
has been paid in full, no amendment, waiver or modification of this Note
(including, without limitation, the subordination provisions hereof), and no
consent to any departure herefrom, that would violate Section 7.17 of the Credit
Agreement shall be effective unless the same shall be in writing and also signed
by the Administrative Agent, and then, in each case, such waiver, modification
or consent shall be effective only in the specific instance and for the specific
purpose for which given.
     10. No Waiver; Cumulative Remedies. No failure on the part of the
Subordinated Creditor or the Administrative Agent to exercise, and no delay in
exercising, any right, power or privilege hereunder shall operate as a waiver
thereof or a consent thereto; nor shall a single or partial exercise of any such
right, power or privilege preclude any other or further exercise thereof or the
exercise of any other right, power or privilege. The remedies provided herein
are cumulative and are not exclusive of any remedies provided by applicable law
or in equity.

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     11. Notices. All notices and other communications provided for herein shall
be in writing and shall be delivered by hand or overnight courier service,
mailed by certified or registered mail or sent by facsimile or electronic mail
(e-mail), as follows:

     
If to Payor:
  Quicksilver Gas Services LP
c/o Quicksilver Gas Services GP LLC
777 West Rosedale Street, Suite 300
Fort Worth, Texas 76104
Attention: MarLu Hiller
FAX: 817-665-5016
Electronic Mail (E-mail): mhiller@qrinc.com
 
   
If to the Subordinated Creditor:
  Quicksilver Resources Inc.
777 West Rosedale Street, Suite 300
Fort Worth, Texas 76104
Attention: MarLu Hiller
FAX: 817-665-5016
Electronic Mail (E-mail): mhiller@qrinc.com
 
   
If to the Administrative Agent:
  Bank of America, N.A.
700 Louisiana Street, 8th Floor
TX4-213-08-14
Houston, Texas 77002
Attention: Ronald E. McKaig
FAX: 713-247-7286
Electronic Mail (E-mail):
ronald.e.mckaig@bankofamerica.com

     12. Assignment. This Note shall be binding upon the successors and assigns
of Payor and shall inure to the benefit of the Subordinated Creditor and its
successors and assigns; provided, however, that Payor shall not assign, delegate
or otherwise transfer any of its rights or obligations under this Note without
the prior written consent of the Subordinated Creditor.
     13. No Credit Support. Payor and the Subordinated Creditor (by its
acceptance hereof) acknowledge and agree that this Note is not secured by any
mortgage, Lien, pledge, charge, financing statement, security interest,
hypothecation, or other security instrument of any type. Payor and the
Subordinated Creditor (by its acceptance hereof) further acknowledge and agree
that this Note is not supported directly or indirectly by any Guarantee of any
person or entity. Payor and the Subordinated Creditor (by its acceptance hereof)
further agree that Payor will not grant, or cause any other Credit Party to
grant any Lien securing this Note or provide any Guarantee for the payment of
this Note until the Senior Debt has been paid in full.
     14. Severability. Any provision of this Note which is prohibited or
unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective
to the extent of such prohibition or unenforceability without invalidating the
remaining provisions hereof; and any such prohibition

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or unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.
     15. Usury Savings Clause. (a) It is the intention of the parties hereto to
comply with applicable state and federal usury laws (now or hereafter enacted).
Accordingly, notwithstanding any provision to the contrary in this Note, in no
event (including, but not limited to, prepayment or acceleration of the maturity
of any obligation) shall this Note require the payment or permit the collection
of interest in excess of the Highest Lawful Rate. If, under any circumstance
whatsoever, any provision of this Note shall provide for the payment or
collection of interest in excess of the Highest Lawful Rate, then, ipso facto,
the obligation to be fulfilled shall be reduced to the limit of such validity,
and if from any such circumstances the Subordinated Creditor shall ever receive
anything of value as interest or deemed interest by applicable law under this
Note or otherwise an amount that would exceed the Highest Lawful Rate, such
amount that would be excessive interest shall be applied to the reduction of the
principal amount owing under this Note or on account of any other indebtedness
of Payor to the Subordinated Creditor, and not to the payment of interest, or if
such excessive interest exceeds the unpaid balance of principal of this Note and
such other indebtedness, such excess shall be refunded to Payor. In determining
whether or not the interest paid or payable with respect to any indebtedness of
Payor to the Subordinated Creditor, under any specified contingency, exceeds the
Highest Lawful Rate, Payor and the Subordinated Creditor shall, to the maximum
extent permitted by applicable law, (i) characterize any non-principal payment
as an expense, fee or premium rather than as interest, (ii) exclude voluntary
prepayments and the effects thereof, (iii) amortize, prorate, allocate and
spread the total amount of interest throughout the full term of such
indebtedness so that interest thereon does not exceed the maximum amount
permitted by applicable law, and/or (iv) allocate interest between portions of
such indebtedness, to the end that no such portion shall bear interest at a rate
greater than that permitted by applicable law.
          (b) If at any time the interest rate hereunder (the “Stated Rate”)
exceeds the Highest Lawful Rate, then the rate at which interest shall accrue
hereunder shall automatically be limited to the Highest Lawful Rate, and shall
remain at the Highest Lawful Rate until the total amount of interest accrued
hereunder equals the total amount of interest that would have accrued but for
the operation of this sentence. Thereafter, interest shall accrue at the Stated
Rate unless and until the Stated Rate again exceeds the Highest Lawful Rate, in
which case the immediately preceding sentence shall apply.
     16. Jurisdiction, Etc. (a) THIS NOTE SHALL BE DEEMED TO BE A CONTRACT UNDER
THE LAWS OF THE STATE OF TEXAS. Payor hereby irrevocably and unconditionally
submits, for itself and its property, to the nonexclusive jurisdiction of the
United States District Court for the Northern District of Texas and of any Texas
State court sitting in Tarrant or Dallas County, Texas, and any appellate court
from any thereof, for purposes of any action or proceeding arising out of or
relating to this Note, or for recognition or enforcement of any judgment, and
Payor hereby irrevocably and unconditionally agrees that all claims in respect
of any such action or proceeding may be heard and determined in any such court.
Payor agrees that a final judgment in any such action or proceeding shall be
conclusive and may be enforced in other jurisdictions by suit on the judgment or
in any other manner provided by law. Nothing in this Note shall affect any right
that the Subordinated Creditor may otherwise have to bring any action or
proceeding relating to this Note in the courts of any jurisdiction.

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          (b) Payor irrevocably and unconditionally waives, to the fullest
extent it may legally and effectively do so, any objection that it may now or
hereafter have to the laying of venue of any suit, action or proceeding arising
out of or relating to this Note in any such court. Payor hereby irrevocably
waives, to the fullest extent permitted by applicable law, the defense of an
inconvenient forum to the maintenance of such action or proceeding in any such
court.
          (c) Payor agrees to not assert any claim against the Subordinated
Creditor, any of its affiliates or any of their respective directors, officers,
attorneys, agents and advisers, for special, indirect, consequential or punitive
damages arising out of or otherwise relating to this Note, any of the
transactions contemplated herein or the actual or proposed use of the loan
evidenced by this Note.
     17. Relationship of the Parties. Notwithstanding any business or personal
relationship between Payor and the Subordinated Creditor, or any officer,
director or employee of the Subordinated Creditor, that may exist or have
existed, the relationship between Payor and the Subordinated Creditor under and
with respect to this Note is solely that of debtor and creditor, the
Subordinated Creditor has no fiduciary or other special relationship with Payor
by virtue of this Note, Payor and the Subordinated Creditor are not partners or
joint venturers, and no term or condition of any of this Note shall be construed
so as to deem the relationship between Payor and the Subordinated Creditor to be
other than that of debtor and creditor.
     18. Right of Set-off. Subject to the subordination provisions contained in
Section 7 hereof, the Subordinated Creditor is hereby authorized at any time and
from time to time, to the fullest extent permitted by applicable law, to set off
and apply any and all indebtedness, obligations or liabilities at any time owing
by the Subordinated Creditor to or for the credit or the account of Payor
against any and all of the obligations of Payor now or hereafter existing under
this Note, whether or not the Subordinated Creditor shall have made any demand
under this Note and although such obligations may be unmatured. The rights of
the Subordinated Creditor under this Section 18 are in addition to other rights
and remedies (including, without limitation, other rights of set off) which the
Subordinated Creditor may have.
     19. Costs and Expenses. Subject to the subordination provisions contained
in Section 7 hereof, Payor agrees to pay on demand all costs and expenses
incurred by the Subordinated Creditor in connection with the preparation,
execution, delivery, administration, modification and amendment of this Note,
including, without limitation, the reasonable attorneys’ fees and expenses of
the Subordinated Creditor with respect thereto and with respect to advising the
Subordinated Creditor as to its rights and responsibilities under this Note.
Subject to the subordination provisions contained in Section 7 hereof, Payor
further agrees to pay on demand all losses, costs and expenses, if any
(including attorneys’ fees and expenses), in connection with the enforcement
(whether through negotiations, legal proceedings or otherwise) of this Note,
including, without limitation, attorneys’ fees and expenses in connection with
the enforcement of rights under this Section 19. In addition, Payor shall pay
any and all stamp and other taxes payable or determined to be payable in
connection with the execution and delivery of this Note, and agrees to save the
Subordinated Creditor harmless from and against any and all liabilities with
respect to or resulting from any delay in paying or omission to pay such taxes.

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     20. Representations and Warranties. Payor hereby represents and warrants to
the Subordinated Creditor that (a) Payor’s execution, delivery and performance
of this Note have been authorized by all necessary action; (b) it has the
requisite power and authority to execute, deliver and perform its obligations
under this Note; (c) this Note has been duly executed and delivered to the
Subordinated Creditor by Payor; and (d) this Note is the legal, valid and
binding obligation of Payor, enforceable against Payor in accordance with its
terms, subject to applicable bankruptcy, insolvency, reorganization, moratorium
or similar laws affecting the enforceability of creditors’ rights generally and
by general principles of equity.
     21. WAIVER OF JURY TRIAL. PAYOR HEREBY IRREVOCABLY WAIVES ANY AND ALL RIGHT
TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS
NOTE.
     22. GOVERNING LAW. THIS NOTE SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF TEXAS, WITHOUT REGARD TO CONFLICTS OF
LAW PRINCIPLES THEREOF.
     23. ENTIRE AGREEMENT. THIS NOTE REPRESENTS THE FINAL, ENTIRE AGREEMENT
BETWEEN THE PARTIES REGARDING THE SUBJECT MATTER HEREOF AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS
OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.
     24. No Recourse. Notwithstanding anything to the contrary in this Note, in
no event shall the Subordinated Creditor have any recourse against the assets of
the Subordinated Creditor or any of its Restricted Subsidiaries (as such term is
defined in the First Supplemental Indenture, dated as of March 16, 2006, by and
among the Subordinated Creditor, the subsidiary guarantors parties thereto and
The Bank of New York, as Trustee (as successor in interest to JPMorgan Chase
Bank, National Association), as such First Supplemental Indenture may be
amended, modified, restated, supplemented or replaced from time to time, or any
comparable term in any other documentation now or hereafter evidencing any
Indebtedness of the Subordinated Creditor) for any of the Subordinated Debt
pursuant to this Note.
[Signature on Following Page]

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     IN WITNESS WHEREOF, Payor has caused this instrument to be duly executed
and delivered to the Subordinated Creditor by a Responsible Officer of the
general partner of Payor on behalf of Payor as of August 10, 2007.

              QUICKSILVER GAS SERVICES LP,
a Delaware limited partnership

    By:   Quicksilver Gas Services GP LLC,
a Delaware limited liability company, its
General Partner                   By:   /s/  MarLu Hiller         MarLu Hiller,
Vice President - Treasurer