Exhibit 10.15
Execution Copy
Base Contract for Sale and Purchase of Natural Gas
This Base Contract is entered into as of the following date: June 1st, 2004 The
parties to this Base Contract are the following:

              J. ARON & COMPANY (“ARON”) and ULTRA RESOURCES, INC.
(“COUNTERPARTY”) 85 Broad Street, New York, NY 10004   363 N. Sam Houston Pkwy.
E., Suite 1200, Houston, TX 77060 Duns # 00-698-0312

  Duns # 07-110-9974

Contract #

  Contract #

Attn: Jim Brush

  Attn: Natural Gas Marketing, Contract Administration

Phone: (212)902-5852

  Fax: 212) 493 9847

  Phone: 281.876.0120 x.307

  Fax: 281.876.2831

Federal Tax ID Number: 13-3092284

  Federal Tax ID Number: 83-0320643

 
            Notices:   Notices, Confirmations, Invoices and Payments: 85 Broad
Street, New York, NY 10004   363 N. Sam Houston Pkwy. E., Suite 1200, Houston,
TX 77060 Attn: Energy Operations, Manager

  Attn: Natural Gas Marketing

Phone: 212-902-7349

  Fax: 212-493 9847

  Phone: 281.876.0120 x.307

  Fax: 281.876.2831

 
            Confirmations:         85 Broad Street, New York, NY 10004        
Attn: Contract Execution Department

       
Phone: 212-357-3606

  Fax: 212-344-3457

       
 
            Invoices and Payments:         85 Broad Street, New York, NY 10004  
      Attn: Energy Operations, Manager

       
Phone: 212-902-7349

  Fax: 212-344-3457

       
 
            Wire Transfer or ACH Nos. (if applicable):   Wire Transfer or ACH
Nos. (if applicable): BANK: Citibank, N.A

  BANK: Bank One N.A.— Chicago

ABA: 021000089,

  ABA: 102001017

ACCT: 09292521

  ACCT: 192 648 101

Other Details: For the account of J. Aron & Co., New York

  Other Details: For the Account of Ultra Resources Inc.

This Base Contract incorporates by reference for all purposes the General Terms
and Conditions for Sale and Purchase of Natural Gas published by the North
American Energy Standards Board. The parties hereby agree to the following
provisions offered in said General Terms and Conditions. In the event the
parties fail to check a box, the specified default provision shall apply. Select
only one box from each section:

                                 
Section 1.2
Transaction
Procedure
þ
o Oral (default) 
Written     Section 7.2
Payment Date þ

o 25th Day of Month following Month of
delivery (default)
_____ Day of Month following Month of delivery                
Section 2.5
Confirm
Deadline
þ
o 2 Business Days after receipt (default)
_____ Business Days after receipt     Section 7.2
Method of
Payment þ
o
o Wire transfer (default)
Automated Clearinghouse Credit (ACH)
Check                
Section 2.6
Confirming
Party
o
o
þ Seller (default)
Buyer
Aron     Section 7.7
Netting þ
o Netting applies (default)
Netting does not apply                
Section 3.2 Performance Obligation
o
þ Cover Standard (default) 
Spot Price Standard     Section 10.3.1
Early Termination
Damages þ
o Early Termination Damages Apply (default)
Early Termination Damages Do Not Apply                     Note: The following
Spot Price Publication applies to both of the Immediately preceding.    
Section 10.3.2
Other Agreement
Setoffs þ
o Other Agreement Setoffs Apply (default)
Other Agreement Setoffs Do Not Apply                    
Section 2.26
Spot Price
Publication
þ
o Gas Daily Midpoint (default) 

 
    Section 14.5
Choice Of Law  
NEW YORK

               
Section 6
Taxes
þ

o Buyer Pays At and After Delivery Point
(default)
Seller Pays Before and At Delivery Point     Section 14.10
Confidentiality o
þ Confidentiality applies (default)
Confidentiality does not apply                 þ  Special Provisions Number of
sheets attached: 4     o  Addendum(s):

   
 
                           

IN WITNESS WHEREOF, the parties hereto have executed this Base Contract in
duplicate.

                J. ARON & COMPANY
    ULTRA RESOURCES, INC.
      By   /s/ Steven D. Pruett     By   /s/ Stuart Nance      Name:   Steven D.
Pruett      Name:   Stuart Nance      Title:   Managing Director      Title:  
Director   

         
    NAESB Standard 6.3.1
April 19, 2002