EXHIBIT 4(a)

                          FIRST SUPPLEMENTAL INDENTURE







                            DENBURY MANAGEMENT, INC.,

                                     Issuer

                             DENBURY RESOURCES INC.,

                                    Guarantor



                      9% Senior Subordinated Notes Due 2008



                          FIRST SUPPLEMENTAL INDENTURE



                           Dated as of April 21, 1999



                   CHASE BANK OF TEXAS, NATIONAL ASSOCIATION,

                                   As Trustee






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     THIS FIRST  SUPPLEMENTAL  INDENTURE,  dated as of April 21,  1999,  between
DENBURY RESOURCES INC., a Delaware  corporation (the "Company"),  and CHASE BANK
OF  TEXAS,  NATIONAL  ASSOCIATION,  as  Trustee  (the  "Trustee"),   amends  and
supplements the Indenture (as defined below).

                                    RECITALS

     WHEREAS,  Denbury  Management,  Inc.("DMI"),  as Issuer,  Denbury Resources
Inc., a corporation formed under the Canadian Business Corporation Act ("Denbury
Canada"), as Guarantor, and the Trustee entered into the Indenture,  dated as of
February 26, 1998 (the  "Indenture"),  relating to DMI's 9% Senior  Subordinated
Notes due 2008 (the "Notes"); and

     WHEREAS,  Denbury  Resources  Inc. has moved its  corporate  domicile  from
Canada  to the  United  States  under  the laws of the  State of  Delaware  (the
"Move"),  and  thereafter,  DMI has  merged  with  and  into  the  Company  (the
"Merger"), with the Company being the surviving entity; and

     WHEREAS,  the Company is required  pursuant to the  Indenture to succeed to
and be  substituted  for,  and  exercise  every right and power of DMI under the
Indenture; and

     WHEREAS,  the Company  has  assumed  and does hereby  assume the direct and
primary obligation to pay the Notes and all DMI obligations under the Indenture,
and by virtue of the Merger and by  operation  of law DMI and the  Company  have
become the same entity, and thus, the Guaranty,  if not otherwise  eliminated by
operation of law, is thereby extinguished; and

     WHEREAS, the Company has furnished to the Trustee an Officer's  Certificate
and Opinion of Counsel as required by Section 5.01(vi) of the Indenture; and

     WHEREAS,  all  conditions  and  requirements  necessary  to make this First
Supplemental  Indenture a valid, binding and legal instrument in accordance with
its terms upon the Company and the Trustee have been fulfilled;

     NOW,  THEREFORE,  in  consideration  of the premises  and mutual  covenants
herein contained and intending to be legally binding,  the parties hereto hereby
agree as follows:

                                   ARTICLE ONE

                            ASSUMPTION OF OBLIGATIONS

     Section 1.01. The Company hereby acknowledges and agrees that, by virtue of
the Merger and by operation of law, it has become a party to the  Indenture  and
has assumed and does hereby assume all of the liabilities and obligations of DMI
under the Indenture and the Notes in accordance  with Section  5.01(i)(B) of the
Indenture.

     Section 1.02. Pursuant to Section 9.05 of the Indenture,  the Company shall
issue and the  Trustee  shall  authenticate  new Notes that  reflect  this First
Supplemental Indenture to be used upon issuance or reissuance of Notes after the
date hereof.

     Section 1.03. Pursuant to Section 9.06 of the Indenture, the Company hereby
indemnifies  and holds  harmless  the  Trustee  from all  liability,  claims and
damages  which the Trustee may sustain or incur by reason of entering  into this
First Supplemental Indenture.

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                                   ARTICLE TWO

                            MISCELLANEOUS PROVISIONS

     Section  2.01.  Capitalized  terms used  herein and not  otherwise  defined
herein are used as defined in the Indenture.

     Section 2.02. This First  Supplemental  Indenture shall be governed by, and
construed in accordance  with,  the laws of the State of New York, as applied to
contracts  made and performed  within the State of New York,  without  regard to
principles of conflict of laws.

     Section  2.03.  This First  Supplemental  Indenture  may be executed in any
number of counterparts,  each of which, when so executed,  shall be deemed to be
an original,  but all of which shall  together  constitute  but one and the same
instrument.

     Section   2.04.   This  First   Supplemental   Indenture  is  an  amendment
supplemental  to the  Indenture and said  Indenture and this First  Supplemental
Indenture shall henceforth be read together.

                                   SIGNATURES

     IN WITNESS WHEREOF,  the parties hereto have caused this First Supplemental
Indenture to be executed as of the day and year first above written.

DENBURY RESOURCES INC.,                         CHASE BANK OF TEXAS, NATIONAL
a Delaware corporation, successor               ASSOCIATION, Trustee
by merger to Denbury Management, Inc.


By:______________________________               By:_____________________________
Name:  Phil Rykhoek                             Name:  Michael D. Scrivner
Title: Chief Financial Officer and Secretary    Title:  Vice President


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