Execution Copy
 Exhibit 2.2
 MEMBERSHIP INTEREST PURCHASE AGREEMENT
 BY AND AMONG
 SM ENERGY COMPANY
 and
 POTATO CREEK LLC
 as SELLERS
 and
 ENDEAVOUR OPERATING CORPORATION
 as BUYER
 Dated July 17, 2011




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TABLE OF CONTENTS
 PageARTICLE 1 Definitions and References
    
    
    11.1 Certain Defined Terms
    
    
    11.2 References and Construction
    
    
    8ARTICLE 2 PURCHASE AND SALE of the InterestS
    
    
    82.1 Purchase and Sale
    
    
    82.2 Purchase Price
    
    
    82.3 Allocation of the Purchase Price
    
    
    9ARTICLE 3 BUYERS INSPECTION
    
    
    113.1 Access
    
    
    113.2 Confidentiality
    
    
    123.3 Disclaimers
    
    
    12ARTICLE 4 TITLE MATTERS; CASUALTIES; ENVIRONMENTAL MATTERS
    
    
    144.1 PCMs Title
    
    
    144.2 Notice of Title Defects; Defect Adjustments
    
    
    144.3 Risk of Loss; Casualty or Condemnation Loss
    
    
    174.4 Environmental Defects
    
    
    174.5 NORM, Wastes and Other Substances
    
    
    19ARTICLE 5 SMS REPRESENTATIONS AND WARRANTIES
    
    
    205.1 Status
    
    
    205.2 Power
    
    
    205.3 Authorization and Enforceability
    
    
    205.4 Ownership and Possession of the SM Interest
    
    
    205.5 Required Government Approvals
    
    
    205.7 Liability for Brokers Fee
    
    
    215.8 Litigation
    
    
    21ARTICLE 6 PCS REPRESENTATIONS AND WARRANTIES
    
    
    216.1 Status
    
    
    216.2 Power
    
    
    216.3 Authorization and Enforceability
    
    
    216.4 Ownership and Possession of the PC Interest
    
    
    216.5 Required Government Approvals
    
    
    226.6 Bankruptcy
    
    
    226.7 Liability for Brokers Fee
    
    
    226.8 Litigation
    
    
    22ARTICLE 7 SELLERS REPRESENTATIONS AND WARRANTIES WITH RESPECT TO PCM
    
    
    227.1 Status
    
    
    227.2 Power
    
    
    22
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TABLE OF CONTENTS
 Page7.3 Capitalization
    
    
    227.4 Conduct of Business
    
    
    237.5 Required Approvals; No Conflict or Violation
    
    
    237.6 Employee Related Matters
    
    
    237.7 Liability for Brokers Fees
    
    
    237.8 Litigation
    
    
    237.9 Contracts
    
    
    237.10 Environmental Compliance
    
    
    247.11 Taxes and Assessments
    
    
    247.12 Compliance with Laws
    
    
    257.13 Permits
    
    
    257.14 Transportation Capacity
    
    
    257.15 No Derivatives
    
    
    267.16 Consents
    
    
    267.17 No Other Representations or Warranties; Disclosed Materials
    
    
    26ARTICLE 8 BUYERS REPRESENTATIONS AND WARRANTIES
    
    
    268.1 Organization and Standing
    
    
    268.2 Power
    
    
    268.3 Authorization and Enforceability
    
    
    268.4 Required Government Approvals
    
    
    278.5 Liability for Brokers Fees
    
    
    278.6 Litigation
    
    
    278.7 Financial Resources
    
    
    278.8 Buyers Evaluation
    
    
    27ARTICLE 9 COVENANTS AND AGREEMENTS
    
    
    279.1 Covenants and Agreements of Sellers
    
    
    279.2 Covenants and Agreements of Buyer
    
    
    299.3 Covenants and Agreements of the Parties
    
    
    29ARTICLE 10 TAX MATTERS
    
    
    2910.1 Non-Income Tax Liability
    
    
    2910.2 Sales Taxes
    
    
    3010.3 Income Taxes
    
    
    3110.4 Tax Reports and Returns
    
    
    31ARTICLE 11 CONDITIONS PRECEDENT TO CLOSING
    
    
    3111.1 Conditions to Obligations of All Parties
    
    
    3111.2 Sellers Conditions
    
    
    3211.3 Buyers Conditions
    
    
    32
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TABLE OF CONTENTS
 PageARTICLE 12 RIGHT OF TERMINATION
    
    
    3312.1 Termination
    
    
    3312.2 Liabilities Upon Termination
    
    
    33ARTICLE 13 CLOSING
    
    
    3413.1 Date of Closing
    
    
    3413.2 Place of Closing
    
    
    3413.3 Closing Obligations
    
    
    34ARTICLE 14 POST-CLOSING OBLIGATIONS
    
    
    3414.1 Post-Closing Adjustments
    
    
    3414.2 Records
    
    
    3514.3 Further Assurances
    
    
    3514.4 Filing of Tax Returns; Payment of Taxes
    
    
    36ARTICLE 15 INDEMNIFICATION; DISCLAIMERS
    
    
    3915.1 Indemnification
    
    
    3915.2 Procedure
    
    
    4015.3 Survival of Warranties, Representations and Covenants
    
    
    4115.4 No Insurance; Subrogation
    
    
    4215.5 Reservation as to Non-Parties
    
    
    4215.6 Reductions in Losses
    
    
    4215.7 Waiver by Buyer
    
    
    42ARTICLE 16 MISCELLANEOUS
    
    
    4216.1 Schedules
    
    
    4216.2 Expenses
    
    
    4216.3 Notices
    
    
    4216.4 Amendments
    
    
    4416.5 Assignment
    
    
    4416.6 Headings
    
    
    4416.7 Counterparts/Fax Signatures
    
    
    4416.8 Governing Law
    
    
    4516.9 Expert Proceedings
    
    
    4516.10 Entire Agreement
    
    
    4516.11 Binding Effect
    
    
    4516.12 No Third-Party Beneficiaries
    
    
    4516.13 Publicity
    
    
    4616.14 Time of the Essence
    
    
    46
 -iii-




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Defined
Terms
    

Section
ReferenceAAA
    
    
    16.9Accounting Arbitrator
    
    
    14.1
    (b)Affiliate
    
    
    1.1Aggregate Deductible
    
    
    4.2
    (e)Agreement
    
    

    PreambleAllocated Value
    
    
    2.3
    (a)Allocation Straddle Period
    
    
    10.1
    (a)Assets
    
    
    1.1Business Day
    
    
    1.1Buyer
    
    
    PreambleBuyer Indemnified Parties
    
    
    15.1
    (a)Buyers Representatives
    
    
    3.1Cap
    
    
    15.1
    (c)Casualty Loss
    
    
    4.3Claim
    
    
    15.2
    (b)Claim Notice
    
    
    15.2
    (a)Closing
    
    
    13.1Closing Date
    
    
    13.1Code
    
    
    1.1Consent
    
    
    5.5Contracts
    
    
    1.1 (Definition of Assets
    )Cure Period
    
    
    4.2
    (b)Dedicated Area
    
    
    1.1Deductible
    
    
    15.1
    (c)Defect Claim Date
    
    
    4.2
    (a)Dispute
    
    
    1.1Dispute Notice
    
    
    14.1
    (a)Effective Time
    
    
    1.1Encumbrance
    
    
    1.1Environmental Arbitrator
    
    
    4.4
    (e)Environmental Condition
    
    
    1.1Environmental Defect
    
    
    1.1Environmental Defect Notice
    
    
    4.4
    (a)Environmental Defect Property
    
    
    4.4
    (a)Environmental Laws
    
    
    1.1Environmental Liabilities
    
    
    1.1Environmental Permits
    
    
    1.1Final Sections 1060 and 751 Allocation Schedule
    
    
    2.3Final Purchase Price
    
    
    14.1
    (a)Final Settlement Date
    
    
    14.1
    (c)Final Settlement Statement
    
    
    14.1
    (a)Force Majeure
    
    
    1.1Fundamental Representations
    
    
    15.1
    (c)Gathering System
    
    
    1.1Governing Documents
    
    
    1.1
 -iv-




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Defined
Terms
    

Section
ReferenceGovernmental Authority
    
    
    1.1Hazardous Materials
    
    
    1.1Indebtedness
    
    
    1.1Indemnified Party
    
    
    15.2
    (a)Indemnifying Party
    
    
    15.2
    (a)Individual Environmental Threshold
    
    
    4.4
    (d)Individual Title Defect Threshold
    
    
    1.1Interests
    
    
    RecitalsInvasive Activities
    
    
    3.1Knowledge
    
    
    1.1Law
    
    
    1.1Losses
    
    
    1.1Material Adverse Effect
    
    
    1.1Non-Income Taxes
    
    
    1.1NORM
    
    
    1.1Obligations
    
    
    1.1Party; Parties
    
    
    PreamblePCM
    
    
    RecitalsPCM Disclosure Schedule
    
    
    Article 7Permits
    
    
    1.1 (Definition of Assets
    )Permitted Encumbrances
    
    
    1.1Person
    
    
    1.1Post-Closing Tax Period
    
    
    14.4
    (d)Pre-Closing Tax Period
    
    
    14.4
    (d)Preliminary Purchase Price
    
    
    2.4Preliminary Settlement Statement
    
    
    2.4Proposed Sections 1060 and 751 Allocation Schedule
    
    
    2.3Purchase Price
    
    
    2.2Records
    
    
    1.1 (Definition of Assets
    )Remediation (Remediate)
    
    
    1.1Remediation Amount
    
    
    1.1Rights-of-Way
    
    
    1.1Sellers
    
    
    PreambleSellers Transaction Costs
    
    
    1.1SM
    
    
    PreambleStraddle Period
    
    
    14.4
    (d)Tax
    
    
    1.1Tax Claim
    
    
    14.4
    (e)Tax Return
    
    
    1.1Title Arbitrator
    
    
    4.2
    (f)Title Defect Amount
    
    
    4.2
    (d)Title Defect Notice
    
    
    4.2
    (a)Title Defect Property
    
    
    4.2
    (a)Transfer Taxes
    
    
    10.2
 -v-




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List of ExhibitsExhibit A
    Dedicated AreaExhibit B
    Real PropertyExhibit C
    Personal PropertyExhibit D
    ContractsExhibit E
    PermitsExhibit F
    Affidavit of Non-Foreign StatusList of
SchedulesSchedule 1.1(k)
    ConsentsSchedule 2.2
    Purchase Price ProportionsSchedule 3.1(f)

    Buyers Insurance RequirementsSchedule 7.9
        Compliance with ContractsSchedule 7.10
        Environmental MattersSchedule 7.13
    Enforceability of Permits
 -vi-




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Agreement th SM PC Sellers Buyer Parties Party
  SM Interest PCM PC Interest Interests
   
 Certain Defined Terms
 Affiliate
 Assets Exhibit B Exhibit C Exhibit D Contracts
 -1-




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Records Exhibit E Permits
 Business Day
 Code
 Control
 Dedicated Area Exhibit A
 Defensible Title
 Dispute
 Effective Time
 Encumbrance
 Environmental Condition
 -2-




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Environmental Defect
 Environmental Laws
 Environmental Liabilities
 Environmental Permits
 Force Majeure
 GAAP
 Gathering System Exhibit A Open Flow
 -3-




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Governing Documents
 Governmental Authority
 Hazardous Materials
 Indebtedness
 Individual Title Defect Threshold
 Knowledge
 Law
 Losses
 -4-




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Material Adverse Effect Material Adverse Effect
 Non-Income Taxes
 NORM
 Obligations
 Permitted Encumbrances
     -5-




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Schedule 1.1(k)
     Person
 Pro Rata Share
 -6-




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PSA
 Release
 Remediation Remediate
 Remediation Amount
 Rights-of-Way
 Sellers Transaction Costs
 Tax
 Tax Return
 Title Defect
  -7-




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References and Construction
   
 Purchase and Sale
 Purchase Price Purchase Price
 Schedule
2.2
  -8-




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Allocation of the Purchase Price
 Exhibit B Allocated Value Exhibit B
 Proposed Sections 1060 and 751 Allocation Schedule Final Sections 1060 and 751 Allocation Schedule
 Adjustments to Purchase Price and Preliminary Settlement Statement Preliminary Settlement Statement Preliminary Purchase Price
 Upward Adjustments
  -9-




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Downward Adjustments
       -10-




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Access.
 Buyers Representatives
 Invasive Activities
 EVEN IF SUCH
LIABILITIES ARISE OUT OF OR RESULT FROM, SOLELY OR IN PART, THE SOLE, ACTIVE, PASSIVE, CONCURRENT
OR COMPARATIVE NEGLIGENCE, STRICT LIABILITY OR OTHER FAULT OR VIOLATION OF LAW OF OR BY ANY SELLER
INDEMNIFIED PARTY, EXCEPTING ONLY LIABILITIES RESULTING FROM OR ARISING OUT OF THE GROSS NEGLIGENCE
OR WILLFUL MISCONDUCT OF A SELLER INDEMNIFIED PARTY
  -11-




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common
undertaking
  Schedule 3.1(f)
 Confidentiality
 Disclaimers
  -12-




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-13-




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PCMs Title
 Notice of Title Defects; Defect Adjustments.
 Title Defect Notices Defect Claim Date Title Defect Notice Title Defect Property
 Remedies for Title Defects
  Cure Period
 -14-




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Exclusive Remedy
 Title Defect Amount Title Defect Amount
      Title Defect Threshold and Deductibles
 -15-




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plus Aggregate Deductible
 Title Dispute Resolution Title
Arbitrator
 -16-




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Risk of Loss; Casualty or Condemnation Loss.
  Casualty Loss
 Environmental Defects.
 Environmental Defects Notice Environmental
Defect Notice Environmental Defect Property
 Remedies for Environmental Defects
 -17-




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Exclusive Remedy
 Environmental Deductibles Individual Environmental Threshold plus
 -18-




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Environmental Dispute Resolution Environmental Arbitrator
 NORM, Wastes and Other Substances
 -19-




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Status
 Power
 Authorization and Enforceability
 Ownership and Possession of the SM Interest
 Required Government Approvals Consent
 Bankruptcy
 -20-




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Liability for Brokers Fee
 Litigation
 
  Status
 Power
 Authorization and Enforceability
 Ownership and Possession of the PC Interest
 -21-




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Required Government Approvals
 Bankruptcy
 Liability for Brokers Fee
 Litigation
 
 Schedule 7 PCM Disclosure Schedule
 Status
 Power
 Capitalization
 -22-




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Conduct of Business
 Required Approvals; No Conflict or Violation
   Employee Related Matters
 Liability for Brokers Fees
 Litigation
 Contracts
 Exhibit D
 Schedule 7.9
   -23-




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Environmental Compliance
  Schedule 7.10
 Taxes and Assessments
    -24-




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Compliance with Laws
 Permits Schedule 7.13 Exhibit E
 Transportation Capacity
 -25-




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No Derivatives
 Consents
 No Other Representations or Warranties; Disclosed Materials
 
  Organization and Standing
 Power
 Authorization and Enforceability
 -26-




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Required Government Approvals
 Liability for Brokers Fees
 Litigation
 Financial Resources
 Buyers Evaluation
 
 Covenants and Agreements of Sellers
 Operations Prior to Closing
 -27-




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Restriction on Operations
          -28-




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Notices of Claims
 Compliance with Laws
 Resignations
 Covenants and Agreements of Buyer
 Covenants and Agreements of the Parties
 Communication Between the Parties Regarding Breach
 Confidentiality
 Governmental Consents
 
 Non-Income Tax Liability
 -29-




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Allocation Straddle Period
  Sales Taxes
 -30-




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Transfer Taxes
 Income Taxes
 Tax Reports and Returns
 
 Conditions to Obligations of All Parties
 Consents and Approvals
 No Injunctions or Restraints
 Conduct of Business
 -31-




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No Action
 Closing of PSA
 Title Defects; Environmental Defects plus
 Sellers Conditions
 Buyers Conditions
 -32-




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Termination
       Liabilities Upon Termination
 Buyers Default
 Sellers Default; Other Termination
 -33-




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Date of Closing Closing Closing Date
 Place of Closing
 Closing Obligations
    Exhibit F
   
 Post-Closing Adjustments
 Final Settlement Statements Final Settlement Statement
 -34-




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Final Purchase Price Dispute Notice
 Accounting Arbitrator
 Final Settlement Date Schedule 2.2 Schedule 2.2
 Records
 Further Assurances
 -35-




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Filing of Tax Returns; Payment of Taxes
     -36-




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Straddle Period Pre-Closing Tax Period Post-Closing Tax
Period
  Tax
Contest
 -37-




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-38-




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Indemnification
 Sellers Indemnification of Buyer Buyer Indemnified Parties
 Buyers Indemnification of Sellers
 Limitations on Indemnity Per Item Threshold Deductible Cap Fundamental
Representations
 -39-




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INCLUDING
RIGHTS TO CONTRIBUTION OR COST RECOVERY UNDER THE COMPREHENSIVE ENVIRONMENTAL RESPONSE,
COMPENSATION AND LIABILITY ACT OF 1980, AS AMENDED, BREACHES OF STATUTORY AND IMPLIED WARRANTIES,
NUISANCE OR OTHER TORT ACTIONS, RIGHTS TO PUNITIVE DAMAGES, COMMON LAW RIGHTS OF CONTRIBUTION, ANY
RIGHTS UNDER INSURANCE POLICIES ISSUED OR UNDERWRITTEN BY THE OTHER PARTY OR ANY OF ITS AFFILIATES,
EVEN IF CAUSED IN WHOLE OR IN PART BY THE NEGLIGENCE (WHETHER SOLE, JOINT OR CONCURRENT), STRICT
LIABILITY OR OTHER LEGAL FAULT OF ANY RELEASED PERSON, INVITEE OR THIRD PERSON, AND WHETHER OR NOT
CAUSED BY A PREEXISTING CONDITION
 Procedure
 Claim Notice Indemnified Party Claim Notice Indemnifying
Party
 -40-




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Information Claim
 Survival of Warranties, Representations and Covenants
 -41-




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No Insurance; Subrogation
 Reservation as to Non-Parties
 Reductions in Losses
 Waiver by Buyer
 
 Schedules
 Expenses
 Notices
 -42-




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-43-




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th
  
  Amendments
 Assignment
 Headings
 Counterparts/Fax Signatures
 -44-




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Governing Law
 Expert Proceedings AAA
 Entire Agreement
 Binding Effect
 No Third-Party Beneficiaries
 -45-




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Publicity
 Time of the Essence
 Signature page follows
 -46-




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SM:SM ENERGY COMPANYBy:
    
    /s/ Kenneth J. Knott

Kenneth J. Knott, Vice President-Business Development and LandPC:POTATO CREEK LLCBy:
    
    Open Flow Gas Supply Corporation,
Managing MemberBy:
    
    /s/ Kevin L. Shannon

Kevin L. Shannon, PresidentBUYER:ENDEAVOUR OPERATING CORPORATIONBy:
    
    /s/ James J. Emme

James J. Emme, Executive VicePresident, North America
 [Signature Page  Membership Interest Purchase Agreement]