EXHIBIT 10.66

                                October 15, 1999

Via Regular Mail
Mr. Vincent M. Brigham
Brigham Land Management Company
P.O. Box 780375
Oklahoma City, OK  73116


         Re:      Amendment to Consulting Agreement
                  Work Performed Within Angleton Project

Dear Vincent:

     This letter  agreement shall set forth the agreement  between Brigham Oil &
Gas, L.P.'s ("BOG") and Brigham Land Management  Company,  Inc. ("BLM") to amend
that certain  Consulting  Agreement dated August 1, 1998, by and between BOG and
BLM (the  "Consulting  Agreement")  with  respect to certain  work that is to be
performed by Vincent M. Brigham within BOG's  Angleton  Project (as described on
Exhibit "A" which is attached hereto).

     Anything  to  the   contrary   contained   in  the   Consulting   Agreement
notwithstanding,  BOG and BLM (BOG and BLM being sometimes collectively referred
to herein as the  "Parties")  agree that any land work  performed  by Vincent M.
Brigham  related to BOG's Angleton  Project,  between  September 6, 1999 and the
earlier to occur of such time as either BOG or BLM  notifies the other that this
amendment is terminated or December 6, 1999 (such time period being  hereinafter
referred to as the "Amendment Term"), shall be governed by the following terms:

(1)  The Fee (as defined in the Consulting  Agreement) for any work performed by
     Vincent M. Brigham shall be $357.50 per day.

(2)  BOG shall not be  required to pay the Fees,  costs or  expenses  related to
     consulting  services  provided by Vincent M. Brigham,  before  December 15,
     1999; however,  BLM shall continue to invoice BOG on a bi-monthly basis for
     all work performed and all costs and expenses  incurred in performing  such
     work in accordance with the terms of the Consulting Agreement. On or before
     December  6, 1999,  BOG shall elect  whether to pay BLM for the  consulting
     services and expenses  which have been  provided and incurred by BLM during
     the Amendment  Term with cash or with an equivalent  overriding  royalty as
     set forth below:

     (A)  In the event that BOG elects to pay for such  consulting  services and
          expenses  with  cash,  BOG will pay BLM for such  consulting  services
          within  15 days of  BOG's  receipt  of BLM's  invoices  for all of the
          consulting  services and expenses  provided and incurred by Vincent M.
          Brigham during the Amendment Term.


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     (B)  In the event that BOG elects to pay for such  consulting  services and
          expenses with an equivalent  overriding royalty,  the BOG Participants
          (as defined  below)  shall grant BLM an  overriding  royalty (the "BLM
          ORRI")  burdening the BOG  Participants'  interests in the first 4 Net
          Wells  (as  defined  below),  if  any,  that  are  drilled  by the BOG
          Participants within the Angleton Project within 10 years from the date
          of this letter  amendment.  The amount of the BLM ORRI shall equal the
          product  obtained by multiplying (i) the product  obtained by dividing
          (a) the total of the Fees and  expenses  for the  consulting  services
          performed  by Vincent M.  Brigham  during  the  Amendment  Term by (b)
          $10,000,  times (ii) .25. The assignment of the BLM ORRI for each well
          shall be in the form which is attached  hereto as Exhibit B, but shall
          not  be  required  to be  completed  and  executed  until  immediately
          preceding the commencement of actual drilling operations for the well.
          The  Parties  recognize  that  the  BLM  ORRI  only  burdens  the  BOG
          Participants'  interests in the first 4 Net Wells,  if any,  which are
          drilled  within the Angleton  Project  within such 10 year period.  As
          such, in the event that any other party  participates  in the drilling
          of any the subject wells, the BLM ORRI will be proportionately reduced
          to the total of the BOG Participants' working interest in the well.

     (C)  For purposes of this letter agreement,  a "BOG  Participant"  shall be
          anyone that BOG assigns part of its interest in oil and gas  leasehold
          or mineral  interests  that are located  within the Angleton  Project,
          insofar and only insofar as the  interest  which is assigned by BOG to
          such party. For example, in the event that BOG assigns to hypothetical
          ABC Company an undivided 25% of BOG's interest in hypothetical Lease A
          covering an  undivided  50% of the  minerals in  hypothetical  Tract 1
          which covers 100 gross acres in the Angleton Project,  for purposes of
          this  letter  agreement,  ABC  Company  would  be  deemed  to be a BOG
          Participant  with  respect to such 25% of BOG's  interest  in Lease A.
          However,  in the event that ABC Company  already owned or subsequently
          acquired hypothetical Lease B which covers the remaining undivided 50%
          of the  minerals in Tract 1 from  someone  other than BOG, ABC Company
          would  not be  deemed  to be a BOG  Participant  with  respect  to its
          interest in Lease B.

     (D)  For purposes of this letter  agreement,  the number of Net Wells shall
          be calculated by the BOG  Participants  total working  interest in the
          wells drilled to date. For every 100% of working  interest held by BOG
          Participants  in wells,  one Net Well shall be deemed to have existed.
          For  example,  in the  event  that at a given  point in time,  the BOG
          Participants  have  participated in the drilling of 3 wells within the
          Angleton Project, the BOG Participants having a total of a 40% working
          interest in the first well,  15% working  interest in the second well,
          and 70%  working  interest  in the  third  well,  in such  event,  for
          purposes  of this  letter  agreement,  1.25 Net Wells  would have been
          drilled  by BOG and BLM's  ORRI  would  burden  the BOG  Participants'
          interest in each of those 3 wells. In the event that BOG  participates
          in more than 4 Net Wells prior to the  expiration of 10 years from the
          date  hereof,  BLM's  ORRI would  burden all of the BOG  Participants'
          interests  in the first  wells  that are spud by the BOG  Participants
          within the Angleton Project which are necessary to cause BLM's ORRI to
          burden 4 Net Wells and in the event that the last well which  would be
          burdened  by the BLM ORRI would cause the BLM ORRI to burden more than
          4 Net Wells,  the BLM ORRI in the last well necessary to cause the BLM
          ORRI to burden 4 Net Wells would be proportionately  reduced such that
          the BLM ORRI burdens  exactly 4 Net Wells.  For example,  in the event
          that the BOG  Participants  have a 50%  working  interest in the first
          well, a 75% working  interest in the second  well,  an 85% interest in
          the third well,  a 90%  working  interest  in the fourth  well,  a 70%
          working  interest in the fifth well and a 65% working  interest in the
          sixth  well  drilled  by the  BOG  Participants  within  the  Angleton
          Project,  the BLM  ORRI  would  burden  all of the  BOG  Participants'
          interests  in the first 5 wells  drilled and would burden only 46.154%
          of  the  BOG  Participants'  interests  in  the  sixth  well  drilled,
          calculated as follows:

                                       2
<PAGE>

          First 5 wells = 3.7 Net Wells

          .3 Net Wells needed out of the 6th well to equal exactly 4 Net Wells
          .65X=.3
          X=.3/.65
          X=46.154%.

These terms  replace all  compensation  provisions  contained in the  Consulting
Agreement  insofar as they would apply to work related to BOG's Angleton Project
performed by Vincent M. Brigham during the Amendment Term. These terms shall not
apply to any work  performed by other  employees,  agents or contractors of BLM,
which work, if any, shall continue to be governed by the terms of the Consulting
Agreement  as  originally  drafted.  Anything to the  contrary  contained in the
Consulting Agreement  notwithstanding,  during the Amendment Term, BLM shall not
have the right to have anyone other than Vincent M. Brigham  perform  consulting
services within the Angleton Project without BOG's prior written consent.

     All  other  terms  of the  Consulting  Agreement,  except  as  specifically
modified herein, shall continue in full force and effect.

     If this letter agreement correctly sets forth the agreement between BOG and
BLM with respect to the amendment to the Consulting  Agreement,  we ask that BLM
execute the duplicate originals of same below.

                                            Sincerely,
                                            BRIGHAM OIL & GAS, L.P.

                                            /s/ David T. Brigham
                                            David T. Brigham
                                            Vice President


<PAGE>

AGREED AND ACCEPTED EFFECTIVE AS OF SEPTEMBER 6, 1999:

BRIGHAM LAND MANAGEMENT COMPANY, INC.


By:   /s/ Vincent M. Brigham

Vincent M. Brigham, President