EXHIBIT 4.12
- --------------------------------------------------------------------------------

                              CODA ENERGY, INC.,
                                   As Issuer


                       DIAMOND ENERGY OPERATING COMPANY
                              TAURUS ENERGY CORP.
                            ELECTRA RESOURCES, INC.
                                 As Guarantors


                                      AND


                   TEXAS COMMERCE BANK NATIONAL ASSOCIATION,
                                  As Trustee

                         ---------------------------- 

                         FIRST SUPPLEMENTAL INDENTURE
                          Dated as of April 25, 1996

                                       to

                                   INDENTURE
                          Dated as of March 18, 1996

                         ----------------------------                          

                                 $110,000,000


                             Series A and Series B
                  10 1/2% Senior Subordinated Notes Due 2006

- -------------------------------------------------------------------------------

 
  FIRST SUPPLEMENTAL INDENTURE, dated as of April 25, 1996, among CODA ENERGY,
INC., a Delaware corporation (the "Company"), as Issuer, DIAMOND ENERGY
OPERATING COMPANY, an Oklahoma corporation, TAURUS ENERGY CORP., a Texas
corporation, and ELECTRA RESOURCES, INC., a Texas corporation, as Guarantors
(collectively, the "Guarantors"), and TEXAS COMMERCE BANK NATIONAL ASSOCIATION,
as Trustee (the "Trustee").

                              W I T N E S S E T H:
                              ------------------- 

  WHEREAS, the Company and the Guarantors have heretofore executed and delivered
to the Trustee a certain indenture, dated as of March 18, 1996 (the
"Indenture"), pursuant to which $110,000,000 aggregate principal amount of 10
1/2% Senior Subordinated Notes Due 2006 (collectively, the "Notes") were issued
by the Company and unconditionally guaranteed by the Guarantors; and

  WHEREAS the Company and the Guarantors desire and have requested the Trustee
to join with it in the execution and delivery of this First Supplemental
Indenture for the purpose of amending Sections 2.06 and 3.07 of the Indenture in
the manner set forth below; and

  WHEREAS, Section 9.01 of the Indenture provides that a supplemental indenture
may be entered into among the Company, the Guarantors, and the Trustee without
the consent of holders of Notes for certain purposes; and

  WHEREAS, the Company and the Guarantors have furnished the Trustee with
Officers' Certificates complying with the requirements of Sections 12.04 and
12.05 of the Indenture and stating that all conditions precedent provided for in
the Indenture with respect to this First Supplemental Indenture have been
complied with; and

  WHEREAS, the Company has furnished the Trustee with an Opinion of Counsel
complying with the requirements of Sections 12.04 and 12.05 of the Indenture and
stating that in the opinion of such counsel all conditions precedent provided
for in the Indenture with respect to this First Supplement Indenture have been
complied with; and

  WHEREAS, all things necessary to make this First Supplemental Indenture a
valid agreement of the Company and the Guarantors and the Trustee and a valid
amendment of and supplement to the Indenture have been done;

  NOW, THEREFORE, THIS FIRST SUPPLEMENTAL INDENTURE WITNESSETH:

  For and in consideration of the premises and the purchase of the Notes by the
holders thereof it is mutually covenanted and agreed for the equal and
proportionate benefit of all holders of the Notes, as follows:

 
     Section 1.01   Amendment of Section 2.06 of the Indenture.
                    ------------------------------------------ 

     Section 2.06 of the Indenture is hereby amended by adding thereto a new
subsection (j) as follows:

     (j)  Transfer of a Beneficial Interest in "IAI" Global Note for Beneficial
          Interest in "QIB" Global Note.

          Any Person having a beneficial interest in that certain Global Note
     (the "IAI Global Note") evidencing interest of Persons who initially
     acquired Notes as "institutional accredited investors" (as defined in Rule
     501 under the Securities Act) may request exchange of such beneficial
     interest for a beneficial interest in that certain Global Note (the "QIB
     Global Note") representing Notes initially issued to Persons who are
     "qualified institutional buyers" (as defined in Rule 144A under the
     Securities Act). Such exchange shall be completed by delivery to the
     Trustee of written instructions or such other form of instructions as is
     customary for the Depository, from the Depository or its nominee, on behalf
     of any Person having a beneficial interest in a Global Note, and, in the
     case of a Transfer Restricted Security, a certification to the effect that
     such beneficial interest is being transferred to a "qualified institutional
     buyer" (as defined in Rule 144A under the Securities Act) in accordance
     with Rule 144A under the Securities Act or pursuant to an exemption from
     registration in accordance with Rule 144 or Rule 9.04 under the Securities
     Act (in substantially the form of Exhibit B hereto) or pursuant to an
     effective registration statement under the Securities Act.

          Upon receipt of such instructions and additional information and
     documents, the Trustee, or the Note Custodian at the direction of the
     Trustee, shall, in accordance with the standing instructions and procedures
     existing between the Depository and the Note Custodian, cause the aggregate
     principal amount of the IAI Global Note to be reduced accordingly by
     endorsement on that certain Schedule of Exchanges of Certificated
     Securities and shall cause the aggregate principal amount of the QIB Global
     Note to be increased accordingly by notation on that certain Schedule of
     Exchanges of Certificated Securities. Notwithstanding any principal amount
     shown outstanding on the face of any Global Note, the notations made on
     said Schedule of Exchanges of Certificated Securities shall control for all
     purposes.

 
     Section 1.02   Amendment to Section 3.07 of the Indenture.  Section 3.07 is
                    ------------------------------------------                  
hereby amended by deleting the existing clause (b) in its entirety and inserting
a new clause (b) therefore as follows:

          (b) Notwithstanding the provisions of clause (a) of this Section 3.07,
     at any time prior to March 12, 1999, the Company may, at its option, on any
     one or more occasions, redeem up to $27.5 million in aggregate principal
     amount of Notes at a redemption price of 110.50% of the principal amount
     thereof, plus accrued and unpaid interest and Liquidated Damages, if any,
     thereon to the redemption date, with the net proceeds of an offering of
     common equity of the Company; provided that at least $82.5 million in
     aggregate principal amount of Notes remains outstanding immediately after
     the occurrence of such redemption; and provided, further, that such
     redemption shall occur within 75 days of the date of the closing of such
     offering of common equity of the Company.

                                  ARTICLE TWO

     Section 2.01   Defined Terms.  All terms used in this First Supplemental
                    -------------                                            
Indenture not otherwise defined herein shall have the meanings ascribed thereto
in the Indenture.

     Section 2.02   Execution in Counterparts.  This first Supplemental
                    -------------------------                          
Indenture may be executed in any number of counterparts.  Each such counterpart
shall be an original, but such counterparts shall together constitute one and
the same instrument.

     Section 2.03   Confirmation of Indenture.  Except as amended and
                    -------------------------                        
supplemented hereby, all of the provisions of the Indenture shall remain and
continue in full force and effect and are hereby confirmed in all respects.

     IN WITNESS WHEREOF, the Company and each of the Guarantors has caused this
First Supplemental Indenture to be duly executed and the Trustee has caused this
First Supplemental Indenture to be duly executed, all as of the day and year
first above written.

                               CODA ENERGY, INC., as Issuer


Attest:                        By: /s/ Grant W. Henderson
/s/ Joe Callaway                  ----------------------------------------------
- ----------------                  Name: Grant W. Henderson
                                        ----------------------------------------
                                  Title: President and Chief Financial Officer
                                         ---------------------------------------

 
                                DIAMOND ENERGY OPERATING
                                COMPANY, as Guarantor

Attest:                         By: /s/ Grant W. Henderson
                                   ---------------------------------------------
/s/ Joe Callaway                    Name: Grant W. Henderson
- ----------------                         ---------------------------------------
                                    Title: Vice President
                                          --------------------------------------


                                TAURUS ENERGY CORP., as Guarantor


Attest:                         By: /s/ Grant W. Henderson
/s/ Joe Callaway                   ---------------------------------------------
- ----------------                    Name: Grant W. Henderson
                                         ---------------------------------------
                                    Title: Vice President
                                          --------------------------------------


                                ELECTRA RESOURCES, INC., as Guarantor


Attest:                         By: /s/ Grant W. Henderson
/s/ Joe Callaway                   ---------------------------------------------
- ----------------                    Name: Grant W. Henderson
                                         ---------------------------------------
                                    Title: President
                                          --------------------------------------


                                TEXAS COMMERCE BANK NATIONAL
                                ASSOCIATION, as Trustee


Attest:                         By: /s/ John G. Jones
/s/ Kathleen Wagner                ---------------------------------------------
- -------------------                 Name: John G. Jones
                                         ---------------------------------------
                                    Title: Vice President
                                          --------------------------------------