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                                                              EXHIBIT 10.22 (g)

                                 AMENDMENT NO. 6
                                       TO
                          MERGER AND PURCHASE AGREEMENT

THIS AMENDMENT NO. 6 TO MERGER AND PURCHASE AGREEMENT (the "Sixth Amendment") is
made as of the 16th day of February, 2000, among Union Pacific Resources
Company, a Delaware corporation, Duke Energy Fuels, LP, now a wholly owned
entity of Buyer, and Duke Energy Field Services, Inc., a Colorado corporation.

         WHEREAS, the parties heretofore entered into a Merger and Purchase
Agreement dated November 20, 1998, which was amended by the Amendment No. 1
dated as of February 1, 1999, Amendment No. 2 dated as of March 5, 1999,
Amendment No. 3 dated as of March 30, 1999, Amendment No. 4 dated as of March
30, 1999, and Amendment No. 5 dated as of May 21, 1999 (collectively, the
"Amended Agreement") (capitalized terms not otherwise defined herein have the
same meanings ascribed to such terms in the Amended Agreement);

         WHEREAS, the parties hereto desire to amend the Amended Agreement as
described below by entering into this Sixth Amendment;

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements, representations, warranties, provisions and covenants herein
contained, the parties hereto hereby agree as follows:

         1. Within 5 days after the execution of this Sixth Amendment, Seller
shall pay Duke Energy Gathering and Processing, L.P. invoice #0200-CONR-200105
in the amount of $132,000. The parties agree that such payment is in complete
and full satisfaction of all obligations of Seller under Section 7.18 of the
Amended Agreement.

         2. Within 5 days after execution of this Sixth Amendment, Seller shall
pay Edwards Cotton Valley, Inc. invoice #0200-EDWD-990180 in the amount of
$627,869.60. The parties agree that such payment is in full and complete
settlement of any and all claims or Damages, known or unknown, which have been
or may be asserted by Buyer in respect of the Edwards Plant (North Fayette
Treater) capacity, operations, capital requirements or completion costs
including, without limitation, the sour water stripper, filter separator, vapor
recovery unit, acid gas injection pump and gas to gas exchanger.

         3. This Sixth Amendment is executed, and shall be considered, as an
amendment to the Amended Agreement and shall form a part thereof, and the
provisions of the Amended Agreement, as amended by this Sixth Amendment, are
hereby ratified and confirmed in all respects.

         4. This Sixth Amendment may be executed in any number of counterparts,
each of which shall be deemed an original, and all of which taken together shall
constitute but one and the

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same instrument. This Agreement shall become binding only when each party hereto
has executed and delivered to the other parties one or more counterparts.

         IN WITNESS WHEREOF, the parties hereto have duly executed this Sixth
Amendment or have caused this Sixth Amendment to be duly executed by their
respective authorized officers as of the day and year first written above.


                                    UNION PACIFIC RESOURCES COMPANY


                                    By:      /s/ Joseph A. LaSala
                                       ----------------------------------------
                                    Name:    Joseph A. LaSala
                                    Title:   Vice President, General Counsel
                                             And Corporate Secretary




                                    DUKE ENERGY FUELS, LP
                                    By:  Fuels Holding Company Operating LLC
                                    Its:  General Partner



                                    By:      /s/ Mark A. Borer
                                       ----------------------------------------
                                    Name:    Mark A. Borer
                                    Title:   Senior Vice President



                                    DUKE ENERGY FIELD SERVICES, INC.


                                    By:      /s/ Mark A. Borer
                                       ----------------------------------------
                                    Name:    Mark A. Borer
                                    Title:   Senior Vice President




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