FIRST
AMENDMENT TO

    PURCHASE
AND SALE AGREEMENT

    


    This
First Amendment to Purchase and Sale Agreement (the “Amendment”)
is made and entered into the 11th day of
February, 2010 and effective as of the Effective Date (as defined in the
Purchase Agreement), by and between TXCO RESOURCES INC., a Delaware corporation, TXCO ENERGY CORP., a Texas corporation, TEXAS TAR SANDS INC., a Texas
corporation, OUTPUT ACQUISITION
CORP., a Texas corporation, OPEX ENERGY, LLC, a Texas
limited liability company, CHARRO ENERGY, INC., a Texas
corporation, TXCO DRILLING
CORP., a Texas corporation, EAGLE PASS WELL SERVICE,
L.L.C., a Texas limited liability company, PPL OPERATING, INC., a Texas
corporation, MAVERICK GAS
MARKETING, LTD., a Texas limited partnership, and MAVERICK-DIMMIT PIPELINE,
LTD., a Texas limited partnership, (collectively, the
“Sellers”),
and NEWFIELD
EXPLORATION COMPANY, a Delaware corporation and ANADARKO E&P COMPANY LP, a
Delaware limited partnership (collectively, the “Purchasers”).  Each
Seller and Purchaser is sometimes
referred to individually as a “Party” and
collectively as the “Parties.”

    


    WITNESSETH:

    


    WHEREAS,
Sellers and Purchasers entered into that certain Purchase and Sale Agreement,
dated January 11, 2010 (the “Purchase
Agreement”), for the sale and purchase of the Assets (as defined in the
Purchase Agreement) of Sellers (capitalized terms used but not defined herein
shall have the meanings set forth in the Purchase Agreement); and

    


    WHEREAS,
Sellers and Purchasers have agreed to modify the Purchase Agreement in certain
respects, all as more particularly set forth in this Amendment to (i)
memorialize the amendment to the Purchase Agreement set forth in Section 1.100
of the Second Amended Plan of
Reorganization for TXCO Resources Inc., et al., Debtors and
Debtors-in-Possession based on Sale of the Debtors’ Assets (the “Plan”),
(ii) memorialize the amendment to the Purchase Agreement set forth in Paragraph
69 of the Order Confirming
Second Amended Plan of Reorganization for TXCO Resources Inc., et al., Debtors
and Debtors-in-Possession based on Sale of the Debtors’ Assets entered in
the Bankruptcy Court on January 29, 2010
(the “Order”),
(iii) supplement or amend certain Exhibits and Schedules to the Purchase
Agreement; and (iv) set forth certain specific assets to be retained by the
Sellers and not acquired by the Purchasers at Closing;

    


    NOW,
THEREFORE, in consideration of the mutual covenants contained herein, and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto do hereby agree as follows:

    


    1.           The
Purchase Agreement is hereby amended by deleting the term “final calculation”
from the first sentence of Section 9.4(b),
and replacing it with the term “estimated calculation.”

    


    
      
         

      

      
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    2.           Section
1.2 of
the Purchase Agreement is hereby amended by deleting the word “and” at the end
of Section 1.2(l), replacing the period with “; and” at the end of Section
1.2(m), and adding the following as new Section 1.2(n):

    


    “(n)       all
rights, including, without limitation, those relating to claims, actions, causes
of action, choses in action, rights of recovery, rights of setoff and rights of
recoupment of any kind or character, in connection with the confidentiality
agreements, to the extent applicable to the Properties or the production of
Hydrocarbons of the Properties, including, without limitation, those listed in
Section 12 of Exhibit
A-3, whether arising or relating to any period prior to or after the
Effective Time; and

    


    3.           Section
1.3(e) of the Purchase Agreement is hereby amended by deleting the text
in the parenthesis and replacing it with “other than the claims or causes of
action described in Section 1.2(n) or
those for proceeds to with the Purchasers are entitled under Section
1.4(b).”

    


    4.           Exhibit A-3 to the
Purchase Agreement is hereby amended as set forth on Exhibit A-3
Supplement attached hereto.

    


    5.           Exhibit A-6 to the
Purchase Agreement is hereby (i) amended by replacing the TXCO Surface and Right
of Way Agreements schedule incorporated by reference on Exhibit A-6 with the
TXCO Surface and Right of Way Agreement schedule attached hereto, and (ii)
amended to add those leases set forth on Exhibit A-6
Supplement attached hereto.

    


    6.           Exhibit A-7 to the
Purchase Agreement is hereby deleted in its entirety and is replaced with the
Exhibit A-7
attached hereto.

    


    7.           Pursuant
to Section 12.12 of the Purchase Agreement, Newfield hereby assigns Newfield’s
right and obligation under the Purchase Agreement to acquire and take assignment
of those Leases set forth on Exhibit C attached hereto, together with all
related Assets, to Newfield Maverick Basin LLC (“Newfield Sub”), a wholly owned
subsidiary of Newfield. Sellers and Anadarko hereby consent to such assignment;
provided, however, that (i) such assignment shall not release Newfield from its
obligations under the Purchase Agreement with respect to such Leases or related
Assets, (ii) Newfield shall be jointly and severally liable with Newfield Sub
for all liabilities and obligations of Newfield Sub under the Purchase Agreement
and any document, instrument or agreement entered into under or pursuant to the
Purchase Agreement relating to such Leases and related Assets, and (iii) such
Leases and related Assets, shall continue to be “Assumed Obligations” and
“Newfield Assets” under the Purchase Agreement.

    


    8.           Except
as modified by this Amendment, all other terms, conditions, covenants,
representations and warranties contained in the Purchase Agreement shall remain
unchanged and in full force and effect and are hereby ratified by the Purchasers
and Sellers.  Upon execution of this Amendment, all references to the
Agreement in the original Purchase Agreement shall be deemed to refer to the
Agreement as amended by this Amendment.

    


    
      
         

      

      
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    9.           This
Amendment may be executed in any number of counterparts and by different parties
hereto in separate counterparts, each of which when so executed shall be deemed
to be an original and all of which taken together shall constitute one and the
same agreement.

    


    [Signature
Page Follows]


    
      
         


      

      
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    IN
WITNESS WHEREOF, Sellers and Purchasers have caused this First Amendment to
Purchase and Sale Agreement to be executed effective as of the Effective
Date.

    


    
      
        
          
            
              
                
                  
                    
                      
                        
                          
                            
                              
                                
                                  
                                    
                                      
                                        
                                          
                                            
                                              
                                                
                                                  	 
      	
                                                          SELLERS:

                                                        
	 
      	 
      
	 
      	
                                                          TXCO
      RESOURCES INC.

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          By:

                                                        	
                                                          /s/ James E. Sigmon

                                                        
	 
      	 
      	
                                                          Name:

                                                        	
                                                          James
      E. Sigmon

                                                        
	 
      	 
      	
                                                          Title:

                                                        	
                                                          Chairman
      and Chief Executive Officer

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          TXCO
      ENERGY CORP.

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          By:

                                                        	
                                                          /s/ James E. Sigmon

                                                        
	 
      	 
      	
                                                          Name:

                                                        	
                                                          James
      E. Sigmon

                                                        
	 
      	 
      	
                                                          Title:

                                                        	
                                                          Chairman
      and Chief Executive Officer

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          TEXAS
      TAR SANDS INC.

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          By:

                                                        	
                                                          /s/ James E. Sigmon

                                                        
	 
      	 
      	
                                                          Name:

                                                        	
                                                          James
      E. Sigmon

                                                        
	 
      	 
      	
                                                          Title:

                                                        	
                                                          Chairman
      and Chief Executive Officer

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          OUTPUT
      ACQUISITION CORP.

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          By:

                                                        	
                                                          /s/ James E. Sigmon

                                                        
	 
      	 
      	
                                                          Name:

                                                        	
                                                          James
      E. Sigmon

                                                        
	 
      	 
      	
                                                          Title:

                                                        	
                                                          Chairman
      and Chief Executive Officer

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          OPEX
      ENERGY, LLC

                                                        
	 
      	 
      	 
      	 
      
	 
      	
                                                          By:

                                                        	
                                                          /s/ James E. Sigmon

                                                        
	 
      	 
      	
                                                          Name:

                                                        	
                                                          James
      E. Sigmon

                                                        
	 
      	 
      	
                                                          Title:

                                                        	
                                                          Chairman
      and Chief Executive
Officer

                                                        


                                                

                                              

                                            

                                          

                                        

                                      

                                    

                                  

                                

                              

                            

                          

                        

                      

                    

                  

                

              

            

          

        

      

    

    


    Signature
Page to First Amendment to Purchase and Sale Agreement


    
      
         


      

      
         


        
          

        

      

      
         


      

    

     

    
      
        
          
            
              
                
                  
                    
                      
                        
                          
                            
                              
                                
                                  
                                    
                                      
                                        
                                          
                                            
                                              
                                                
                                                  
                                                    
                                                      
                                                        
                                                          
                                                            
                                                              
                                                                
                                                                  
                                                                    	 
      	
                                                                            CHARRO
      ENERGY, INC.

                                                                          
	 	 
	 
      	
                                                                            By:

                                                                          	
                                                                            /s/ James E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Name:

                                                                          	
                                                                            James
      E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Title:

                                                                          	
                                                                            Chairman
      and Chief Executive Officer

                                                                          
	 	 	 	 
	 
      	
                                                                            TXCO
      DRILLING CORP.

                                                                          
	 	 	 	 
	 
      	
                                                                            By:

                                                                          	
                                                                            /s/ James E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Name:

                                                                          	
                                                                            James
      E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Title:

                                                                          	
                                                                            Chairman
      and Chief Executive Officer

                                                                          
	 	 	 	 
	 
      	
                                                                            EAGLE
      PASS WELL SERVICE, L.L.C.

                                                                          
	 	 	 	 
	 
      	
                                                                            By:

                                                                          	
                                                                            /s/ James E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Name:

                                                                          	
                                                                            James
      E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Title:

                                                                          	
                                                                            Chairman
      and Chief Executive Officer

                                                                          
	 	 	 	 
	 
      	
                                                                            PPL
      OPERATING, INC.

                                                                          
	 	 	 	 
	 
      	
                                                                            By:

                                                                          	
                                                                            /s/ James E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Name:

                                                                          	
                                                                            James
      E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Title:

                                                                          	
                                                                            Chairman
      and Chief Executive Officer

                                                                          
	 	 	 	 
	 
      	
                                                                            MAVERICK
      GAS MARKETING, LTD.

                                                                          
	 	 	 	 
	 
      	
                                                                            By:

                                                                          	
                                                                            /s/ James E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Name:

                                                                          	
                                                                            James
      E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Title:

                                                                          	
                                                                            Chairman
      and Chief Executive Officer

                                                                          
	 	 	 	 
	 
      	
                                                                            MAVERICK-DIMMIT
      PIPELINE, LTD.

                                                                          
	 	 	 	 
	 
      	
                                                                            By:

                                                                          	
                                                                            /s/ James E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Name:

                                                                          	
                                                                            James
      E. Sigmon

                                                                          
	 
      	 
      	
                                                                            Title:

                                                                          	
                                                                            Chairman
      and Chief Executive
Officer

                                                                          


                                                                  

                                                                

                                                              

                                                            

                                                          

                                                        

                                                      

                                                    

                                                  

                                                

                                              

                                            

                                          

                                        

                                      

                                    

                                  

                                

                              

                            

                          

                        

                      

                    

                  

                

              

            

          

        

      

    

    


    Signature
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                          PURCHASERS:

                        
	 	 
      	 
      	 
      
	 	
                          ANADARKO
      E&P COMPANY LP

                        
	 	 
      	 
      	 
      
	 	
                          By:

                        	
                          /s/ Joseph F. Carroll

                        
	 	 
      	
                          Name:

                        	
                           Joseph
      F. Carroll

                        
	 	 
      	
                          Title:

                        	
                          Attorney-in-fact

                        


                

              

            

          

        

      

    

    


    Signature
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                      NEWFIELD
      EXPLORATION COMPANY

                    
	 	 
      	 
      	 
      
	 	
                      By:

                    	
                      /s/ William D. Schneider

                    
	 	 
      	
                      Name:

                    	
                      William
      D. Schneider

                    
	 	 
      	
                      Title:

                    	
                      Vice
      President - Onshore

                    
	 	 
      	 	      
                      Gulf
      Coast & International


                    


            

          

        

      

    

    


    Signature
Page to First Amendment to Purchase and Sale Agreement