PURCHASE AND SALE AGREEMENT

                                     between

                         TIPPERARY OIL & GAS CORPORATION

                                    As Seller

                                       And

                           NANCE PETROLEUM CORPORATION

                                    As Buyer

                                      DATED

                                 APRIL 10, 2000

<PAGE>

                                TABLE OF CONTENTS

1.       Assets to be Sold and Purchased; Reservation of Surface Estate        1

2.       Purchase Price; and Taxes                                             2

3.       Warranties, Representations, and Covenants                            3

4.       Seller's Disclaimer of Warranties, Representations, and Covenants     5

5.       Certain Covenants of Seller Pending Closing                           6

6.       Due Diligence and Environmental Reviews                               7

7.       Certain Purchase Price Adjustments                                   12

8.       Record Retention Following Closing                                   13

9.       Conditions Precedent to the Obligations of Buyer                     13

10.      Conditions Precedent to the Obligations of Seller                    14

11.      Termination of Agreement                                             14

12.      The Closing                                                          15

13.      Certain Adjustments                                                  17

14.      Environmental Indemnity and Hazardous Substances                     18

15.      Commissions                                                          20

16.      Casualty Loss                                                        20

17.      Notices                                                              21

18.      Survival of Provisions                                               21

19.      Operations                                                           21

20.      Confidentiality Agreement                                            22

21.      Further Assurances                                                   22

<PAGE>

22.      Governing Law, and Venue                                             22

23.      Costs                                                                22

24.      Entire Agreement; Amendment; and Waiver                              22

25.      Section and Other Headings; and Construction                         22

26.      Severability                                                         23

27.      Attorney's Fee                                                       23

28.      Restrictions on Assignment                                           23

29.      Time of the Essence                                                  23

30.      Parties in Interest; Successors and Assigns                          23

31.      No Publicity                                                         23

32.      No Recording                                                         24

EXHIBIT A -                                Leases

EXHIBIT B -                                Wells and Allocated Value

EXHIBIT C -                                Quitclaim Assignment and Bill of Sale

EXHIBIT D -                                Preferential Rights

EXHIBIT D-1 -                              Officer's Certificate

EXHIBIT D-2 -                              Officer's Certificate

EXHIBIT E -                                Non-Foreign Affidavit

<PAGE>

                           PURCHASE AND SALE AGREEMENT

     This Purchase and Sale  Agreement  ("Agreement")  is entered into this 10th
day of April,  2000,  by and between  Tipperary Oil & Gas  Corporation,  a Texas
corporation  ("Seller"),  the address of which is 633 17th  Street,  Suite 1550,
Denver,  Colorado 80202, and Nance Petroleum Corporation,  a Montana corporation
("Buyer"),  the address of which is 550 North 31st Street,  Suite 500, Billings,
Montana 59101.

                                    RECITALS:

     A. Seller has certain oil and gas interests  that it wants to sell to Buyer
in accordance with the terms of this Agreement.

     B. Buyer wants to buy all of Seller's  right,  title,  and interest in said
oil and gas interests in accordance with the terms of this Agreement.

     NOW THEREFORE, for and in consideration of the terms of this Agreement, the
adequacy of which is hereby acknowledged, the parties agree as follows:

     1. Assets to be Sold and  Purchased;  Reservation  of Surface  Estate.  (a)
        -------------------------------------------------------------------
Subject  to and in  accordance  with the terms  hereof,  Seller  agrees to sell,
assign,  and convey to Buyer,  and Buyer agrees to purchase from Seller,  all of
Seller's  right,  title,  and  interest,  if any, in and to the  following  real
property,  fixtures,  and  personal  property,  but  only  insofar  as they  are
attributable   to  the  real  property   described  in  Exhibit  A  hereto  (the
"Property"):

          (i) any and  all  oil,  gas and  other  mineral  interests,  including
Seller's right, title, and interest,  if any, in all: (A) oil and gas leases and
any other mineral leases, (B) royalties and overriding royalties, (C) production
payments,  (D) net profits interests,  (E) reversionary  mineral interests,  (F)
unitization,  pooling, and communitization  agreements, and (G) declarations and
orders (including all units formed under orders,  rules,  regulations,  or other
official acts of any federal, state, or other authority having jurisdiction, and
voluntary unitization agreements, designations and declarations), subject to any
exceptions and reservations contained in Exhibit A;

          (ii) all fixtures,  equipment,  and other  personal  property,  to the
extent  relating  to the wells  described  in  Exhibit  B and their  appurtenant
production,   storage,  treating,   gathering,  and  transportation  facilities,
situated on the Property; and

          (iii) all  contracts;  lease  files;  abstracts  and  title  opinions;
production records;  well files;  permits and licenses;  accounting records (but
excluding all general financial accounting or tax accounting records that do not
pertain exclusively to the Property); electric logs and geological, geophysical,
engineering, and other technical data and records (subject to any contractual or
other restrictions relating to the transfer of such data and records); and other
files,  documents  and records that directly  relate to the  Property;  provided
however,  Seller may  retain  copies of any or all of the

                                       1

<PAGE>


foregoing.  If  Seller  retains  any  such  copies,  they  shall be  treated  as
confidential  and  may be  disclosed  only  under  conditions  analogous  to the
exclusions from confidentiality set forth in the Confidentiality Agreement dated
January 20, 2000 between Seller and Buyer ("Confidentiality Agreement").

Seller's  interests,  if any,  in the  real  property,  fixtures,  and  personal
property  described  in  subsections  (i) and  (ii) are  sometimes  collectively
referred  to as "Oil  and Gas  Properties,"  or as an  "Oil  and Gas  Property".
Seller's  interests,  if any, in the Oil and Gas  Properties and in the personal
property  described in subsection  (iii) are sometimes  collectively  called the
"Assets."

     (b)  Notwithstanding  anything herein to the contrary,  Seller will reserve
unto itself all of its right,  title,  and interest in and to the surface estate
of the Property (to the extent of any surface  estate  interests  not created by
lease,  easement,  or  right-of-way),  and all rights of any  nature  whatsoever
appurtenant  or  otherwise  associated  therewith,  and such right,  title,  and
interest will not constitute any part of the Assets;  provided  however,  Seller
will grant Buyer the right to use the surface of the Oil and Gas  Properties for
purposes reasonably necessary or incidental to oil and gas operations on the Oil
and Gas Properties,  but Buyer shall protect, defend, indemnify, and hold Seller
harmless  from and against any and all Claims  (hereinafter  defined) or Damages
(hereinafter defined) resulting from such use.

     (c) Except for: (i) easements and rights-of-way of record, (ii) other third
party rights (if any) that could not reasonably be expected to have a materially
adverse  effect  on the  use of the  Assets,  and  (iii)  liens  for  taxes  and
assessments due but not yet payable, Seller warrants title to the Assets against
anyone claiming any interest therein arising by, through,  or under Seller,  but
Seller makes no other warranty, representation, or covenant, express or implied,
statutory or otherwise, as to title to the Assets.

     2.  Purchase  Price;  and  Taxes.  (a) The  purchase  price for the  Assets
         -----------------------------
("Purchase  Price") shall be Seven Million  Eight Hundred  Twenty-Five  Thousand
Dollars ($7,825,000) as adjusted as provided herein. The Purchase Price shall be
paid  at  the  Closing  (hereinafter  defined)  as  hereinafter  provided.  Said
$7,825,000, without regard to any adjustments, however, is sometimes referred to
herein as the "Base Purchase Price."

     (b) Upon  execution  of this  Agreement,  Buyer  shall pay to Seller  Seven
Hundred Eighty-Two Thousand Five Hundred Dollars ($782,500) ("Deposit") by check
drawn on a national bank in immediately  available funds. If for any reason said
check  should be  dishonored,  then at Seller's  option,  and in addition to any
other rights it may have, it may terminate this  Agreement.  If Buyer and Seller
consummate  the purchase and sale of the Assets,  the Deposit  shall be credited
against the Purchase Price. The Deposit shall be returned to Buyer:

          (i) only if:(A) Seller  refuses to consummate the purchase and sale of
the Assets and (B) such refusal would constitute a breach hereof, or

          (ii) only under the circumstances, if any, expressly set forth herein.

                                       2

<PAGE>

If Buyer fails to consummate the transactions contemplated by this Agreement, or
if the  transactions  contemplated by this Agreement  otherwise fail to close on
the Closing  Date,  Seller shall retain the Deposit as liquidated  damages.  The
parties  agree that damages in such an event are  uncertain in amount and cannot
be  determined  with  reasonable  certainty  in advance,  that the amount of the
Deposit   constitutes   a  fair  and   reasonable   estimate   of  (and  is  not
disproportionate  to) actual  Damages such a breach  would  cause,  and is not a
penalty or an inducement to perform.

     (c) Buyer shall pay any and all sales, use, documentary, and transfer taxes
and fees imposed on this  transaction,  and shall pay all  recording  and filing
fees.

     3. Warranties, Representations, and Covenants. (a) Each party, as to itself
        -------------------------------------------
only, warrants, represents, and covenants to the other party that:

          (i) It is a corporation  duly organized,  legally existing and in good
standing  under  the laws of the  state of its  incorporation,  as first set out
above.

          (ii) It is  qualified to do business and is, or at Closing will be, in
good  standing  in each state in which the Oil and Gas  Properties  are  located
where  the laws of such  state  require  a  corporation  owning  the Oil and Gas
Properties located in such state to qualify to do business.

          (iii) It has full  power to enter  into and  perform  its  obligations
under this Agreement; the execution, delivery, and performance of this Agreement
and the  consummation  of the  transactions  contemplated  hereby have been duly
authorized by all requisite  corporate action;  and this Agreement has been duly
executed and delivered.

          (iv) This Agreement,  and the Assignment  (hereinafter  defined) to be
delivered at Closing, will, when executed,  delivered, and accepted,  constitute
its legal,  valid and binding  obligation,  enforceable  in accordance  with its
terms,  except as limited by  bankruptcy or other laws  applicable  generally to
creditor's rights and as limited by general equitable principles.

          (v)(A) There are no pending or threatened material suits,  actions, or
other proceedings to which it is a party that affect: (I) the Assets (including,
as to Seller, any actions challenging or pertaining to its title to any Assets),
or (II) the execution and delivery of this Agreement or the  consummation of the
transactions  contemplated  hereby,  and (B) it shall promptly  notify the other
party of any such material  suits,  actions,  or other  proceedings  as to which
after the date hereof it receives a written threat of assertion.

          (vi) It shall protect, defend,  indemnify, and hold harmless the other
party and its affiliates,  and their employees,  agents, successors and assigns,
from and with respect to any and all rights, claims,  demands, causes of action,
and legal,  administrative,  or arbitration proceedings, of any and every nature
(collectively,  "Claims"), and injuries, deaths, damages, and obligations of any
and  every  nature  resulting  from or that gave  rise to any  Claim,  including
liabilities,  losses, costs, penalties, expenses, judgments, fines, settlements,
interest,  reasonable  attorney's fees, and other related expenses of any nature
(collectively,   "Damages")   resulting   from  a  breach  of  its   warranties,

                                       3

<PAGE>

representations,  or covenants; provided however, that Damages shall not include
consequential, special, incidental, or punitive damages.
     (b) Seller warrants and represents to Buyer that:

          (i) Other than:

               (A)  requirements (if any) that consents to assignment of Assets,
or  waivers  of  preferential  rights to  purchase  Oil and Gas  Properties,  be
obtained from third parties, or

               (B)  requirements  to obtain  consents or approvals  from,  or to
submit  notices  to or  applications  to,  or  actions  that  must be taken  by,
governmental  entities  (in their  capacity  as lessors  of oil and gas  leases,
grantors of  rights-of-way,  or otherwise,  whether similar to or different from
the foregoing) in connection  with the sale or conveyance of oil and gas leases,
permits, or interests therein, or of rights or interests of the nature of any of
the  Assets,  if the same are  customarily  obtained  contemporaneously  with or
subsequent to such sale or conveyance, or

               (C) neither its execution and delivery of this Agreement, nor its
consummation of the transactions  contemplated  hereby,  nor its compliance with
the terms  hereof,  will violate or result in any default  under its articles of
incorporation  or by-laws,  or under any  agreement to which it is a party or by
which it is bound, or violate any Law (hereinafter  defined) applicable to it or
to the Assets.

          (ii)  It has not  received  notice  of any  Claims  (including  Claims
regarding environmental matters) pending or threatened against it arising out of
its ownership of the Assets that is material as to any such Asset,

          (iii) All wells on the property  that were operated by Seller but that
were  plugged  and  abandoned  prior to the  Effective  Date  were  plugged  and
abandoned in accordance  with good industry  practice and in compliance with all
Laws.

          (iv) To the best of Seller's knowledge,  and subject to the provisions
of this  subsection  (iv), the production and expense data, and any  supplements
thereto,  heretofore  furnished  or  caused to be  furnished  by Seller to Buyer
(sometimes referred to herein as "P&E Information"),  was substantially complete
and  correct  as of the  date of  such  delivery;  provided  however,  that  the
foregoing  applies  only  to  matters  of  fact,  and  does  not  apply  to  any
information, data, printouts, extrapolations,  projections, documentation, maps,
graphs, charts, or tables that reflect, depict, present,  portray, or represent,
or which are based upon or derived from, in whole or in part,  interpretation of
the P&E Information, including matters of geological, geophysical,  engineering,
or scientific interpretation.

          (v) To the  best  of  Seller's  knowledge:  (A)  it has  all  material
governmental  licenses and permits,  and has properly made all material  filings
necessary to obtain the permits and licenses, to own and operate the Assets, (B)
such  permits,  licenses,  and  filings  are in full  force and  effect,  (C) no
material violations exist regarding any such permits,  licenses or filings,  and
(D) no proceeding to challenge,  revoke, or limit any such permit,  license,  or
filing is pending or threatened.

                                       4

<PAGE>

          (vi) To the best of Seller's knowledge: (A) it is not obligated by any
prepayment   arrangement  under  any  contract  for  the  sale  of  hydrocarbons
(including  take  or  pay  obligations,  hedging  or  forward  sale  or  similar
agreements,  or  production  payments  or any  other  arrangements)  to  deliver
hydrocarbons  from the Assets at some future  time  without  then or  thereafter
receiving full payment  therefor,  (B) there are no production  sales agreements
regarding the Assets  currently in effect that require more than sixty (60) days
prior  written  notice to  terminate,  and (C) there are no calls on  production
affecting the Assets.

          (vii) To the best of Seller's  knowledge,  there are no surface use or
access agreements  currently in force and effect that would materially interfere
with oil and gas operations on the Oil and Gas Properties.

          (viii) To best of Seller's knowledge,  no well listed on Exhibit B has
been  represented  by  its  operator,  either  in a  pending  authorization  for
expenditures or other written  proposal to other working  interest owners in any
such well, as presently needing to be plugged and abandoned.

     (c) Buyer warrants and represents to Seller that:

          (i)  It  is a  knowledgeable  and  experienced  purchaser,  owner  and
operator of oil and gas  properties,  has the  ability to  evaluate  oil and gas
properties,  and,  subject  to its  rights  under  Section 6, has been given the
opportunity to investigate and evaluate (and has investigated and evaluated) the
condition of the Assets to the extent it deems  necessary or appropriate  and is
acquiring the Assets based solely upon its own  investigation and evaluation and
for its own  account,  and not with a view to or the  intent to make a resale or
distribution within the meaning of the Securities Act of 1933 (and the rules and
regulations pertaining thereto) or a resale or distribution thereof in violation
of any other applicable securities laws.

          (ii)  With  regard to those  Assets  that it seeks to  operate,  it is
qualified to operate such Assets under the applicable  Laws of the  jurisdiction
in  which  such  Assets  are  located  and  under  the  Laws  of  all  governing
authorities,  or will become so  qualified  (and assumes the risk of becoming so
qualified) before operating such Assets.

          (iii) Neither its execution  and delivery of this  Agreement,  nor its
consummation of the transactions  contemplated  hereby,  nor its compliance with
the terms  hereof,  will violate or result in any default  under its articles of
incorporation  or by-laws,  or under any  agreement to which it is a party or by
which it is bound, or violate any Law applicable to it or to the Assets.

     4. Seller's Disclaimer of Warranties,  Representations,  and Covenants. (a)
        --------------------------------------------------------------------
WITH RESPECT TO THE ASSETS,  THIS AGREEMENT,  AND THE TRANSACTIONS  CONTEMPLATED
HEREBY, SELLER'S WARRANTIES AND REPRESENTATIONS AS EXPRESSLY SET OUT IN SECTIONS
1(c), 3, 5(a), and 5(c)(i) HEREOF AND IN THE ASSIGNMENT EXECUTED PURSUANT HERETO
ARE EXCLUSIVE AND IN LIEU OF ANY AND ALL OTHER WARRANTIES,  REPRESENTATIONS, AND
COVENANTS,  EXPRESS OR IMPLIED, STATUTORY OR OTHERWISE, AND SELLER DISCLAIMS ANY
AND ALL OTHER WARRANTIES, REPRESENTATIONS, AND COVENANTS.

                                       5

<PAGE>

     (b) CONSISTENT  WITH AND NOT AS A LIMITATION ON SUBSECTION  (a), THE ASSETS
SHALL BE PURCHASED,  SOLD, AND CONVEYED "AS IS, WHERE IS", WITHOUT ANY WARRANTY,
REPRESENTATION,  OR  COVENANT,  EXPRESS  OR  IMPLIED,  STATUTORY  OR  OTHERWISE,
RELATING TO:

          (i) THE CONDITION, QUANTITY, QUALITY, FITNESS FOR A PARTICULAR PURPOSE
OR  ANY  PURPOSE,   CONFORMITY  TO  THE  MODELS  OR  SAMPLES  OF  MATERIALS,  OR
MERCHANTABILITY  OF  ANY  IMMOVABLE  PROPERTY,   MOVABLE  PROPERTY,   EQUIPMENT,
INVENTORY, MACHINERY, AND OTHER FIXTURES AND PERSONAL PROPERTY CONSTITUTING PART
OF THE ASSETS;

          (ii) ANY IMPLIED OR EXPRESS WARRANTY OF FREEDOM FROM REDHIBITORY VICES
OR DEFECTS OR OTHER VICES OR DEFECTS, WHETHER KNOWN OR UNKNOWN;

          (iii) ANY AND ALL IMPLIED  WARRANTIES,  REPRESENTATIONS,  OR COVENANTS
EXISTING UNDER APPLICABLE LAW NOW OR HEREAFTER IN EFFECT; AND

          (iv) EXCEPT AS PROVIDED  OTHERWISE IN THE SUBSECTION (a),  WITHOUT ANY
OTHER WARRANTY,  REPRESENTATION,  OR COVENANT,  EXPRESS OR IMPLIED, STATUTORY OR
OTHERWISE.

     (c)  CONSISTENT  WITH BUT NOT AS A LIMITATION ON  SUBSECTIONS  (a) AND (b),
SELLER IS SELLING  AND BUYER IS BUYING THE ASSETS  WITH ALL  DEFECTS  AND FAULTS
(LATENT OR  APPARENT)  AND IT ASSUMES  THE RISK THAT  ADVERSE  PAST,  PRESENT OR
FUTURE PHYSICAL CONDITIONS MAY NOT HAVE BEEN REVEALED BY ITS INVESTIGATIONS.

     5. Certain Covenants of Seller Pending Closing. Between the date hereof and
        --------------------------------------------
the Closing Date:

     (a)  Seller  will give  Buyer,  its  attorneys  and other  representatives,
subject to the  provisions of the  Confidentiality  Agreement and subject to any
restrictions  on access to the Assets  imposed by  agreements by which Seller is
bound,  access at all  reasonable  times to: (i) the  Assets  and (ii)  Seller's
records and files  relating to the Assets (which records and files include those
relating to title, division orders, wells,  production,  accounting,  marketing,
equipment  inventories,  and  production,   severance  and  ad  valorem  taxes).
Notwithstanding  the  foregoing,  Seller shall not be obligated to provide Buyer
with  access  to any files or  records  that  Seller  considers  proprietary  or
confidential  to it or that it  cannot  legally  provide  to Buyer  without,  in
Seller's opinion,  breaching or risking a breach of confidentiality  agreements.
All such files and records are being made available to Buyer  (whether  pursuant
to this  Section or  otherwise)  as an  accommodation,  and without  warranty or
covenant,  express or implied,  statutory or  otherwise,  as to the accuracy and
completeness of such materials;

                                       6


<PAGE>

provided however, that notwithstanding the foregoing,  Seller represents that to
the  best of its  knowledge,  all  such  files  and  records  are  substantially
complete.

     (b) To the extent Seller is the operator of any Oil and Gas Properties,  it
will continue such operation in the ordinary  course of its business;  and where
it is not the  operator  of any Oil and Gas  Properties,  it will  continue  its
actions as a non-operator  in the ordinary  course of its business.  Seller will
not sell or dispose of any portion of the Assets without Buyer's prior consent.

     (c)(i)  Seller  represents  that to the  best of its  knowledge,  the  only
preferential  purchase  rights  that exist with  respect to its  interest in the
Assets are listed in Exhibit D. Seller will use reasonable  efforts,  consistent
with industry  practices in transactions of this type, to identify all rights to
require that  consents to  assignment  of any Assets be obtained,  and the third
parties  holding any of such rights.  In attempting  to identify the  foregoing,
however,  Seller shall not be obligated  to review  anything  other than its own
records.  Seller will request,  from the third parties  listed in Exhibit D and,
with  respect  to  the  aforementioned  third  parties  so  identified  (and  in
accordance with the documents creating such rights), waivers of the preferential
rights to purchase and  requirements  that  consents to  assignment  be obtained
which were so identified.  Seller shall have no obligation  hereunder other than
to so attempt to identify such requirements for consents to assignment and to so
request waivers of such consents and of preferential  purchase rights, but shall
have no obligation to obtain such waivers or consents.

          (ii) If the holder of a preferential  right to purchase an Asset fails
or refuses to give such waiver and  instead  exercises  such right,  Seller will
tender to such  holder (at a price  equal to the amount  specified  in Exhibit B
hereto for the wells located on such Asset and for the units in which such Asset
participates,  reduced appropriately,  as determined by Seller, if less than the
entire  Asset  should be  tendered,  unless it is  determined  that a greater or
lesser  price  is  required)  the  interest  in  the  Asset   affected  by  such
preferential  right.  If such  interest in such Asset is  actually  sold to such
holder,  it will be excluded from the  transaction  contemplated  hereby and the
Purchase  Price  will be  reduced  by the  amount  paid to Seller by the  holder
exercising such right.

     (d)  Notwithstanding  anything in this Section to the contrary:  (i) Seller
may take any action  prohibited  by this Section if reasonably  necessary  under
emergency  conditions,  provided  that Buyer is notified as soon as  practicable
thereafter;  (ii)  except to the extent a "Defect" (  hereinafter  defined)  may
result  therefrom,  Seller shall have no  liability  to Buyer for any  incorrect
payment of delay rentals,  royalties,  shut-in  royalties or similar payments or
for any failure to make such payments; and (iii) Seller=s failure to comply with
any of the  requirements of this Section shall not be deemed a default by Seller
hereunder or entitle Buyer to not close the  transactions  contemplated  hereby,
unless such failure has a materially  adverse  impact on the value of the Assets
taken as a whole.

     6. Due Diligence  and  Environmental  Reviews.  (a)(i) To the extent deemed
        -------------------------------------------
appropriate  by Buyer,  it may  conduct,  at its sole cost and risk,  such title
examinations  and,  subject to any  restrictions  to which Seller is bound,  any
other reasonable  examinations and  investigations as it may choose with respect
to the Assets; provided however,  environmental  examinations and investigations
shall be governed by  subsection  (b). If as a result of such  examinations  and
investigations  Buyer  identifies any matters that  constitute  Defects,  and if
there are any Defects that

                                       7

<PAGE>

Buyer is unwilling to waive,  Buyer must notify Seller of such Defects  ("Defect
Notice") promptly following its discovery of such Defects, but in no event later
than April 24, 2000  ("Defect  Date").  Buyer may not give notice of any Defects
after the Defect Date, and must accept all Defects, if any, discovered after the
Defect Date.

          (ii) To be effective,  a Defect Notice must include: (A) a description
of  the  Property   affected,   (B)  a  description  of  the  particular  matter
constituting  the  alleged  Defect,  (C) such  supporting  documents  reasonably
necessary for Seller to determine if a Defect actually  exists,  and (D) Buyer's
good faith  estimate of the amount by which the alleged Defect reduces the value
attributed to the  Property.  Alleged  Defects for which Buyer  provides a valid
Defect Notice prior to the Defect Date are herein called "Asserted Defects."

          (iii) Except for Asserted  Defects,  all matters that might  otherwise
constitute  a Defect are waived for all  purposes  hereof.  With  respect to any
Asserted  Defect,  Seller  shall have the right but not the  obligation  to: (A)
attempt to cure it prior to Closing,  (B) require  that the Closing  take place,
deposit in an escrow account the portion of the Purchase Price paid by Buyer and
attributable to the Asset having the Asserted  Defect,  and attempt to cure such
Asserted  Defect  within sixty (60) days after the Closing,  and Seller=s  right
under this clause (B) may be exercised at any time before the Closing  Date;  or
(C) elect not to cure the  Asserted  Defect  and adjust  the  Purchase  Price as
provided Section 7.

          (iv) With respect to any Oil and Gas  Property,  if a title opinion or
any  other  materials  reviewed  by Buyer  indicates  Seller  has a Net  Revenue
Interest  (hereinafter defined) greater than that specified on Exhibit B without
a corresponding  proportionate  increase in the Operating Interest  (hereinafter
defined),  then Buyer shall promptly inform Seller of the same, but in any event
at least five (5) days prior to the Closing.  If Seller or Buyer  determine that
Seller is entitled to a Net Revenue  Interest in any Asset in excess of that set
forth on Exhibit B ("NRI Increase"), notice shall promptly be given to the other
party, and the adjustments to be made under Section 7 shall include  adjustments
which are the subject of such notice.

     (b)(i)(A) To the extent,  if any,  that Seller has the right to grant Buyer
the right to do so,  Buyer may,  upon at least four (4) day's  notice to Seller,
enter upon the Oil and Gas Properties to conduct an environmental  assessment of
the  Assets at  Buyer's  sole cost and risk.  (B)  Consistent  with but not as a
limitation on the foregoing,  Buyer shall protect,  defend,  indemnify, and hold
Seller and anyone else owning an interest in the Oil and Gas Properties harmless
from  and  against  any  Claims  and  Damages  resulting  from the  presence  or
activities of Buyer or its agents on the Oil and Gas Properties in the course of
conducting its assessment activities.

          (ii) In conducting  its  assessment,  and subject to  subsection  (i),
Buyer may enter upon the Oil and Gas Properties,  without disrupting  operations
thereon,  and inspect the same,  conduct soil and water tests and  borings,  and
generally conduct such tests, examinations,  investigations,  and studies as may
be necessary or appropriate for the  preparation of appropriate  engineering and
other reports in relation to the Oil and Gas Properties,  their  condition,  and
the presence of Hazardous Substances  (hereinafter defined). Any such assessment
shall be  concluded  no later than  April 24,  2000  ("Environmental  Assessment
Date"). If there are any Oil and Gas Properties as to which Seller does not have
the right to grant Buyer the right to conduct an assessment,  then no later than

                                       8

<PAGE>

the  Environmental  Assessment Date, or if as a result of Buyer's  environmental
assessment  any particular Oil and Gas Property is determined to be in violation
of environmental  Laws, then Buyer may notify Seller that Buyer wants to exclude
such Asset from this Agreement (and such notice,  if and to the extent regarding
a violation of environmental  Laws,  shall provide in reasonable  detail the Law
that was  violated,  the manner in which such Law was violated,  and  sufficient
information  to  substantiate  the  violation),  in which event said Oil and Gas
Property  shall be excluded and the Purchase  Price shall be reduced,  with such
reduction  in the  Purchase  Price  being  determined  in  the  same  manner  as
reductions  for  Asserted  Defects  under  Section  7.  After the  Environmental
Assessment  Date:  (A) Buyer may not  request  that any Oil and Gas  Property be
excluded from this  Agreement,  and (B) Buyer shall be deemed to have  inspected
the Oil and Gas  Properties  or waived its right to  inspect  the Assets for all
purposes and satisfied itself as to their physical and environmental  condition,
both  surface  and  subsurface,   including,  but  not  limited  to,  conditions
specifically  related  to  the  presence,  release,  or  disposal  of  Hazardous
Substances.

          (iii)(A) Buyer shall provide  Seller with a copy of any  environmental
assessment and other reports,  and all supporting data and other  documentation,
promptly  upon  completion  of the  assessment.  Buyer  shall  keep  any data or
information  acquired by such  examinations  and the results of all  analyses of
such data and information  strictly  confidential and shall not disclose them to
anyone  without  Seller's  prior  written  approval,  which need not be given of
Seller.

               (B) The consent  required by subsection  (A) shall not apply to a
disclosure to a  governmental  agency that Buyer believes upon written advice of
counsel is required by Law;  provided however,  that in such event,  Buyer shall
give notice to Seller  (which  notice shall  describe in a  reasonably  detailed
manner the legal  grounds on which such  advice is based) at least ten (10) days
prior to making such disclosure,  and shall take into account any comments Buyer
may  receive  from  Seller.  Seller  shall have the right to contest the need to
disclose any such information,  and Buyer shall protect, defend,  indemnify, and
hold Seller  harmless from any Claims or Damages  resulting  from any disclosure
that was not required by Law.

     (c) As used  herein,  "Defect"  means any matter,  other than a  "Permitted
Encumbrance" (hereinafter defined), which causes one or more of the following to
be a correct statement:

          (i)  Seller's  ownership  of an Asset is such that,  with respect to a
well or unit listed on Exhibit B, such ownership: (A) is insufficient to entitle
it to receive a decimal  share of the oil, gas and other  hydrocarbons  produced
from,  or allocated  to, such well or unit that is at least equal to the decimal
share set  forth on  Exhibit  B in the  column  "Net  Revenue  Interest"  or (B)
obligates it to bear a decimal share of the cost of operating  such well or unit
("Operating  Interest") greater than the decimal share set forth on Exhibit B in
the  column  "Operating  Interest"  without  a  proportionate  increase  in  the
corresponding Net Revenue Interest set forth on such Exhibit;

          (ii)  Seller's  ownership  of an Oil and Gas Property is subject to an
outstanding and valid  mortgage,  deed of trust,  other lien or encumbrance,  or
other  adverse claim or  imperfection  in title,  which if asserted  would cause
either subsection (i)(A) or (i)(B) to be a correct statement; or

          (iii) Seller's  represented amount of any gas imbalances is materially
inaccurate.

                                       9

<PAGE>

     (d) As used herein,  "Permitted  Encumbrance" shall mean any and all of the
following:

          (i) The conditions, restriction, exceptions, reservations, limitations
and all other terms  contained in the agreements and instruments in the chain of
title that  creates or  reserves to Seller its  interest in any Asset,  provided
that the same do not reduce Seller's Net Revenue  Interest in the affected Asset
to less than that set forth on Exhibit B;

          (ii) Royalties,  overriding  royalties  (including those  specifically
described on Exhibit A), division  orders,  reversionary  interests,  production
payments,  net profits  interests and similar burdens  affecting any Oil and Gas
Property if the net cumulative  effect of such burdens does not reduce  Seller's
Net  Revenue  Interest  in the  affected  Asset to less  than  that set forth on
Exhibit B;

          (iii) Preferential  rights to purchase,  requirements that third party
consents be obtained for assignments,  and agreements of a similar nature,  with
respect  to  which  waivers  or  consents  shall  have  been  obtained  from the
appropriate  parties,  or the appropriate  time period for asserting such rights
shall have expired without an exercise of such rights;

          (iv) Liens for taxes and  assessments  which are not yet delinquent or
which are being  contested by Seller in good faith and for which Seller  retains
responsibility;

          (v) Rights existing under applicable Laws (including  statutory liens)
or operating  agreements  or similar  contracts,  pursuant to which liens may be
asserted  against the Assets,  but  excluding  liens and other  rights that have
actually been asserted  unless Seller disputes the validity of such liens or the
amount  claimed to be owed in connection  therewith and for which Seller retains
responsibility,  or such  lien or other  right is not  enforceable  against  the
interest of Seller;

          (vi) Conventional rights of reassignment requiring ninety (90) days or
less notice to the holder of such rights;

          (vii) Easements,  rights-of-way,  servitudes,  permits, surface leases
and other rights in respect to surface operations,  pipelines,  logging, canals,
ditches,  reservoirs or the like;  conditions,  covenants or other restrictions;
easements for streets,  alleys,  highways,  pipelines,  telephone  lines,  power
lines, railways and other easements or rights-of-way on, over or with respect of
any Asset  which do not  materially  and  adversely  affect  the Asset  affected
thereby or its current use;

          (viii)  Any   obligations   or  duties   affecting  an  Asset  to  any
municipality or public authority with respect to any franchise,  grant,  license
or permit and all applicable Laws of any governmental authority;

          (ix) All  requirements  to obtain  consents or approvals  from,  or to
submit  notices  to or  applications  to,  or  actions  that  must be taken  by,
governmental  entities  (in their  capacity  as lessors  of oil and gas  leases,
grantors of  rights-of-way,  or otherwise,  whether similar to or different from
the foregoing) in connection  with the sale or conveyance of oil and gas leases,
permits, or interests

                                       10

<PAGE>

therein,  or of rights or interests  of the nature of any of the Assets,  if the
same are customarily obtained  contemporaneously with or subsequent to such sale
or conveyance;

          (x)  Existing  operating  agreements,  unit  agreements,  gas purchase
contracts and any and all other  agreements  that are typical in the oil and gas
exploration,  development,  production or extraction business or in the business
of processing of gas and gas  condensate  or  production  for the  extraction of
proper  products  therefrom,  to the  extent  that the same do not:  (A)  reduce
Seller's Net Revenue  Interest in the affected Asset to less than that set forth
on Exhibit B, or (B) increase Seller's  Operating Interest in the affected Asset
to greater than set forth on Exhibit B without a  proportionate  increase in the
corresponding Net Revenue Interest set forth on such Exhibit;

          (xi) Any other defect or imperfection in title which would customarily
be waived by a reasonable person engaged in the business of owning and operating
oil and gas properties; and

          (xii) Any other matter waived or deemed to be waived by Buyer pursuant
to the provisions of subsection (a).

     (e) With respect to all Assets conveyed to Buyer hereunder:

          (i) BUYER SHALL BE DEEMED TO HAVE:  (A)  INSPECTED,  OR TO HAVE WAIVED
ITS RIGHT TO INSPECT,  THE ASSETS FOR ALL PURPOSES,  AND (B) SATISFIED ITSELF AS
TO THEIR  PHYSICAL AND  ENVIRONMENTAL  CONDITION,  BOTH SURFACE AND  SUBSURFACE,
INCLUDING CONDITIONS SPECIFICALLY RELATED TO THE PRESENCE,  RELEASE, OR DISPOSAL
OF SOLID WASTES, ASBESTOS, OTHER MANMADE FIBERS, NATURALLY OCCURRING RADIOACTIVE
MATERIALS,  AND  OTHER  HAZARDOUS  SUBSTANCES  IN,  ON, OR UNDER THE OIL AND GAS
PROPERTIES AS OF THE DEFECT DATE.

          (ii) BUYER SHALL BE DEEMED TO HAVE RELIED SOLELY ON ITS OWN INSPECTION
OF THE  ASSETS,  AND AS  PROVIDED  IN SECTION 4,  SELLER IS SELLING AND BUYER IS
BUYING ALL ASSETS "AS IS, WHERE IS."  CONSISTENT WITH BUT NOT AS A LIMITATION ON
THE  FOREGOING,  EXCEPT AS MAY OTHERWISE BE EXPRESSLY  PROVIDED  HEREIN,  SELLER
MAKES NO WARRANTY REPRESENTATION,  OR COVENANT, EXPRESS OR IMPLIED, STATUTORY OR
OTHERWISE,  AS TO THE ACCURACY OR  COMPLETENESS OF ANY DATA,  REPORTS,  RECORDS,
PROJECTIONS,  INFORMATION,  OR OTHER  MATERIALS  NOW,  HERETOFORE,  OR HEREAFTER
FURNISHED  OR MADE  AVAILABLE  TO  BUYER  IN  CONNECTION  WITH  THIS  AGREEMENT,
INCLUDING PRICING ASSUMPTIONS OR QUALITY OR QUANTITY OF HYDROCARBON RESERVES (IF
ANY)  ATTRIBUTABLE  TO THE ASSETS OR THE ABILITY OR  POTENTIAL  OF THE ASSETS TO
PRODUCE  HYDROCARBONS OR THE ENVIRONMENTAL  CONDITION OF THE ASSETS OR ANY OTHER
MATERIALS  FURNISHED OR MADE  AVAILABLE TO BUYER BY OR ON BEHALF OF SELLER.  ANY
AND ALL  SUCH  DATA,  REPORTS,  RECORDS,  PROJECTIONS,  INFORMATION,  AND  OTHER
MATERIALS  FURNISHED BY OR ON BEHALF OF SELLER TO BUYER ARE PROVIDED TO BUYER AS
A

                                       11

<PAGE>

CONVENIENCE  AND SHALL NOT CREATE OR GIVE RISE TO ANY LIABILITY OF OR AGAINST
SELLER;  ANY CONCLUSIONS,  IMPLICATIONS,  OR INFERENCES DRAWN THEREFROM SHALL BE
THE RESULT OF BUYER'S OWN INDEPENDENT  REVIEW; AND ANY RELIANCE ON OR USE OF THE
SAME SHALL BE AT BUYER'S SOLE RISK.

     7. Certain  Purchase Price  Adjustments.  (a) If in connection with the due
        -------------------------------------
diligence  review  under  Section 6 either:  Asserted  Defects are  presented to
Seller and Seller is unable or unwilling to cure such Asserted  Defects prior to
the Closing,  Buyer has elected to treat an Oil and Gas  Property  affected by a
casualty  loss as if it was an Oil  and Gas  Property  affected  by an  Asserted
Defect, or an NRI Increase occurs, then:

          (i) Buyer and Seller shall,  with respect to each Oil and Gas Property
affected by such matters, attempt to agree upon an appropriate adjustment to the
Purchase Price to account for such matters; and

          (ii) With  respect to each Oil and Gas  Property as to which Buyer and
Seller are unable to agree upon appropriate  adjustment with respect to all such
matters affecting such Oil and Gas Property:

               (A) If the Asserted  Defect is a mortgage,  deed of trust,  lien,
encumbrance or other charge which is undisputed  and liquidated in amount,  then
the adjustment  shall be the amount  necessary to be paid to remove the Asserted
Defect from the affected Asset;

               (B) If there is:  (I) an  Asserted  Defect or NRI  Increase  that
represents  a  discrepancy  between  the Net  Revenue  Interest  that  Seller is
entitled  to  receive  from any Asset  and the Net  Revenue  Interest  stated on
Exhibit B, and (II) an Operating Interest change  proportionate to the change in
the Net Revenue  Interest  resulting  from the Asserted  Defect or NRI Increase,
then the amount of the adjustment shall be the product of the value allocated to
such  Asset as set  forth on  Exhibit  B  ("Allocated  Value")  multiplied  by a
fraction, the numerator of which shall be the change in the Net Revenue Interest
and the  denominator  of which  shall be the Net Revenue  Interest  set forth on
Exhibit B;

               (C) If the Asserted Defect represents an obligation, encumbrance,
burden,  discrepancy  or charge  upon or other  defect in title to the  affected
Asset of a type not described in subsections  (A) or (B), the adjustment  amount
shall be determined  by taking into account the Allocated  Value of the Asset so
affected,  the portion of the Asset affected by the Asserted  Defect,  the legal
effect of the Asserted  Defect,  the potential  economic  effect of the Asserted
Defect  over the  life of the  affected  Asset  and such  other  factors  as are
necessary to make a proper evaluation of the value of the Asserted Defect;

               (D) Notwithstanding any other provision contained herein: (I) the
aggregate  reduction  attributable to the effect of all Asserted Defects related
to a given Asset shall not exceed the  Allocated  Value of such Asset unless the
Asserted  Defect is of the nature  described in subsections (A) or (C), in which
event the reduction shall be of the nature  described in subsections

                                       12

<PAGE>

(A) or (C),  even if it exceeds the Allocated  Value of such Asset;  and (II) no
reduction  shall be made with respect to an Asserted Defect if the diminution in
the Allocated  Value  regarding such Asset  resulting  therefrom  regarding said
asset will not exceed One Thousand Dollars ($1,000.00); and

               (E) If the parties cannot agree upon an appropriate adjustment in
light of the factors set forth above,

then,  subject to subsection  (b)(ii),  Seller may elect to exclude such Oil and
Gas Property from the transaction  contemplated  hereby,  and the Purchase Price
will be reduced by the Allocated  Value of the wells located on such Oil and Gas
Property and the units in which such Oil and Gas Property participates.

     (b)(i) If the aggregate  Purchase Price  reduction which would result under
subsection (a) does not exceed One Hundred Thousand Dollars ($100,000), then the
Purchase  Price shall not be  adjusted,  and none of the Oil and Gas  Properties
which would be excluded by such procedure shall be excluded.

          (ii) If the aggregate  Purchase Price reduction exceeds $100,000,  the
Purchase Price shall be adjusted by the total amount of such  reduction.  If the
Purchase  Price  increase  which  would  result  under  subsection  (a)  exceeds
$100,000,  the  Purchase  Price shall be  adjusted  by the total  amount of such
increase.

     (c) If the aggregate  amount of all Purchase  Price  reductions  under this
Agreement,  regardless  of the reason for such  reductions,  exceeds ten percent
(10%) of the Base Purchase  Price,  either party may terminate this Agreement by
giving  notice  to the  other  party  within  ten  (10)  days of the date it was
determined  that the  Purchase  Price would exceed said 10%, in which event this
Agreement shall terminate and the Deposit shall be returned to Buyer.  Upon such
termination,  the  parties  shall have no  further  obligations  to one  another
hereunder (other than the  indemnification  obligations  under Sections 3(a)(vi)
and 6(b), and the  obligations  under Sections 11(c), 15 and 20 - 27, which will
survive such termination).

     8. Record  Retention  Following  Closing.  If the  purchase and sale of the
        --------------------------------------
Assets is  consummated,  then for a period of seven (7) years from the  closing,
Buyer shall save and retain, and give Seller access at all reasonable times upon
reasonable  notice,  to all files and records  (including all computer  records)
delivered  by  or on  behalf  of  Seller  in  connection  with  the  transaction
contemplated  hereby,  and shall permit  Seller to make copies of any such files
and  records.  Consistent  with but not as a  limitation  on Section  30, if the
Assets are subsequently transferred by Buyer, Buyer shall take all action in its
contractual  arrangements relating to such transfer necessary to allow Seller to
have continued access to all such files and records.

     9. Conditions  Precedent to the Obligations of Buyer. Buyer's obligation to
        --------------------------------------------------
purchase the Assets is subject to each of the following conditions being met:

     (a) Each and  every  warranty  and  representation  of  Seller  under  this
Agreement shall be true and accurate in all material respects as of Closing, the
same as if made at Closing,  except as to changes  specifically  contemplated by
this Agreement or waived by Buyer.

                                       13

<PAGE>

     (b) Seller  shall have  complied in all material  respects  (or  compliance
shall have been waived by Buyer) with each and every  covenant  required by this
Agreement to be performed by Seller prior to or at the Closing.

     (c) No suit, action or other proceedings shall, on the date of Closing,  be
pending,  or  threatened  in writing,  before any court or  governmental  agency
seeking to restrain,  prohibit,  or obtain damages or other relief in connection
with the consummation of the transactions contemplated by this Agreement.

     (d) Any and all other  conditions  precedent  in  Buyer's  favor  have been
satisfied or waived.

     10. Conditions Precedent to the Obligations of Seller.  Seller's obligation
         --------------------------------------------------
to sell the Assets is subject to each of the following conditions being met:

     (a) Each  and  every  warranty  and  representation  of  Buyer  under  this
Agreement shall be true and accurate in all material respects as of Closing, the
same as if made at Closing,  except as to changes  specifically  contemplated by
this Agreement or waived by Seller.

     (b) Buyer shall have complied in all material respects (or compliance shall
have been  waived by  Seller)  with each and  every  covenant  required  by this
Agreement to be performed by Buyer prior to or at the Closing.

     (c) No suit, action or other proceedings shall, on the date of Closing,  be
pending,  or  threatened  in writing,  before any court or  governmental  agency
seeking to restrain,  prohibit,  or obtain damages or other relief in connection
with the consummation of the transactions contemplated by this Agreement.

     (d) Any and all other  conditions  precedent  in  Seller's  favor have been
satisfied or waived.

     11. Termination of Agreement. (a) If: (i) any condition precedent set forth
         -------------------------
in Section 9 to Buyer's  obligation  to purchase the Assets is not  satisfied or
waived as of the Closing Date, or if the Closing does not occur on or before May
9, 2000 ("Termination Date"), and (ii) Buyer is not in breach of its obligations
hereunder, then Buyer may terminate this Agreement upon seven (7) days notice to
Seller,  and  Seller  shall  promptly  return the  Deposit  to Buyer.  Upon such
termination,  the  parties  shall have no  further  obligations  to one  another
hereunder (other than the  indemnification  obligations  under Sections 3(a)(vi)
and 6(b), and the obligations  under subsection (c) and Sections 15 and 20 - 27,
which will survive such termination).

     (b) If: (i) any  condition  precedent  set forth in Section 10 to  Seller's
obligation to sell the Assets is not satisfied or waived as of the Closing Date,
or if the Closing  does not occur on or before the  Termination  Date,  and (ii)
Seller is not in breach of its obligations hereunder (unless Buyer shall also be
in  breach  of its  Obligations  hereunder),  then  Seller  may  terminate  this
Agreement  upon  seven (7) days  notice to Buyer,  and Seller  shall  return the
Deposit to Buyer only if the termination was based solely on Section 10(c). Upon
such termination,  the parties shall have no further  obligations to one another
hereunder (other than the  indemnification  obligations  under Sections 3(a)(vi)
and

                                       14

<PAGE>

6(b),  and the  obligations  under  subsection  (c) and Sections 15 and 20 - 27,
which will survive such termination).

     (c) Upon  termination  of this  Agreement  under  subsection (a) or (b), or
under Section 7(c),  Seller may sell the Assets (or any portion  thereof) to any
other party without any  limitation  under or by reason of this  Agreement,  and
Buyer may not seek to enjoin any such sale. Promptly following Seller's request,
Buyer  shall:  (i) execute any  instrument  requested  by Seller to evidence the
termination  of Buyer's  right to acquire the Assets,  and (ii) return to Seller
all data and other information (and all copies thereof) furnished to Buyer by or
on behalf of Seller in connection with this transaction.

     12. Closing;  and Post-Closing  Matters.  (a)(i) The closing ("Closing") of
         ------------------------------------
the transaction  contemplated  hereby shall take place in the offices of Seller,
in Denver,  Colorado,  on May 3, 2000, at 10:00 a.m.  Mountain  Time, or at such
other date and time as Buyer and Seller may agree ("Closing Date").

                  (ii) At least five (5) business  days before the Closing Date,
Seller shall submit to Buyer a proposed statement ("Closing  Statement") setting
forth the  proposed  Purchase  Price,  based on the  adjustments  for which this
Agreement  provides.  At least two (2)  business  days before the Closing  Date,
Buyer shall  deliver to Seller a written  report  proposing and  explaining  any
changes to the Closing  Statement;  provided  however,  if Buyer fails to timely
deliver  such  report,  Seller's  Closing  Statement  shall be the basis for the
Purchase  Price.  If Buyer timely  delivers such report,  Seller and Buyer shall
make every reasonable effort to agree upon an acceptable Purchase Price prior to
Closing,  but if the  parties  fail to reach such  Agreement,  then at  Seller's
election:  Seller's  estimation  of the  adjustments  shall be employed  for the
purpose of Closing,  the Closing shall occur, and differences  shall be resolved
after the Closing.

     (b) At the Closing, Seller shall:

          (i) execute,  acknowledge  and deliver to Buyer an Assignment and Bill
of Sale  ("Assignment")  of the Assets, in the form attached hereto as Exhibit C
(with Exhibits A and B hereto being attached  thereto),  effective as to runs of
oil and  deliveries of gas as of 7:00 a.m.,  Mountain  Standard Time on March 1,
2000 ("Effective Date");

          (ii) execute and deliver to Buyer  letters in lieu of transfer  orders
(or similar documents), in form acceptable to both parties;

          (iii) execute and deliver to Buyer an affidavit or other certification
(as permitted by the Internal Revenue Code of 1986) having the form and language
as  Exhibit E  attached  hereto,  to the  effect  that  Seller is not a "foreign
person"  within the  meaning  of Section  1445 (or  similar  provisions)  of the
Internal Revenue Code of 1986; and

          (iv) provide Buyer with Seller's Officer  Certificate  having the form
and language of Exhibit D-1 attached hereto.

     (c) At the Closing, Buyer shall:

                                       15

<PAGE>

          (i) deliver to the Seller by wire  transfer in  immediately  available
funds,  to an  account  designated  by Seller in a bank  located  in the  United
States, an amount equal to the Purchase Price minus the Deposit,  as such amount
may be adjusted in accordance with the terms hereof;

          (ii) with respect to Assets operated by Seller, execute and deliver to
Seller  appropriate  evidence  reflecting  change of  operator  as  required  by
applicable  authorities  and such  evidence as Seller may require  that Buyer is
qualified with such authorities to succeed Seller as operator; and

          (iii) provide Seller with Buyer's Officer  Certificate having the form
and language of Exhibit D-2 attached hereto.

     (d) Within five (5) days after  Closing,  Seller will  deliver to Buyer the
records and other materials described in Section 1(a).

     (e) Following the Closing,  with respect to each Oil and Gas Property as to
which Seller is disbursing proceeds of production  attributable to other parties
entitled thereto, Seller shall:

          (i)  continue to collect  proceeds of  production  during the month in
which Closing occurs and be responsible for making disbursements,  in accordance
with  its  normal  procedures  (and at  normal  times),  of such  proceeds  from
production so collected to the parties  entitled to same, with any proceeds from
production thereafter collected by Seller to be promptly forwarded to Buyer (who
shall thereafter account for same to the parties entitled thereto), and

          (ii) deliver to Buyer:  (A) a copy of its proceeds  distribution  list
(but Seller makes no warranties or  representations,  express or implied,  as to
the  accuracy of such list) for each such Asset  (which  list shall  include the
name,  address,  social security or tax number, and applicable share of proceeds
from  production for each party to whom Seller is disbursing  such proceeds with
respect  to such  Asset),  (B) a list of all  parties  for whom it is holding in
suspense  proceeds  from  production,  (C) a list of all  parties for whom it is
holding  in any  advance  payments  made by other  working  interest  owners for
operations  to be  conducted  on the  Assets,  and (D) a check  (which  shall be
delivered  within 30 days after the end of the month in which Closing occurs) in
an amount equal to all suspended funds and advance payments.  Following delivery
of the materials referred to in this subsection,  Buyer shall be responsible for
all  disbursements  of proceeds from  production  (including  suspense and other
disbursements  attributable  to periods  prior to the  Effective  Date) and such
disbursement  activities  shall be included in the matters which Buyer  assumes,
and  indemnifies  Seller  with  respect to,  hereunder,  except that Buyer shall
neither  assume  responsibility,   nor  indemnify  Seller,  for  any  penalties,
interest, or attorney's fees attributable to such suspense funds insofar as such
relate to periods prior to the Effective Date.

     (f) All  production  attributable  to Seller's  interest in the Oil and Gas
Properties,  and all proceeds from the sale thereof, including proceeds from the
sale of any oil in  storage  above the  pipeline  connection,  and any  accounts
receivable  balances  and any  related  Claims  and  Damages,  any of which  are
attributable  to  production  prior to the Effective  Date,  shall be and remain
Seller's

                                       16

<PAGE>

property. All such production therefrom, and all proceeds from the sale
thereof,  attributable  to production  after the Effective Date shall be Buyer's
property.

     (g) Buyer shall  execute,  acknowledge  and file the  Assignment for record
immediately  upon  receipt  thereof  and will  furnish  to  Seller a copy of the
recorded  document  promptly after Buyer's  receipt of such recorded  instrument
from the clerk in each county or parish in which the Assignment is recorded.  In
addition, where applicable, Buyer and Seller shall execute any forms required to
effect a change of operator for all wells conveyed herein.

     (h)(i) Following the Closing, Buyer shall:

               (A) Promptly take all actions  necessary to succeed Seller as the
party to any leases, rights-of-way, contracts, bonds, permits, licenses, and any
other  instrument,   and  to  all  duties,   obligations,   and  liabilities  to
individuals,  private entities, or governmental authorities, with respect to the
Assets to which Seller was a party or by which it was bound,

               (B) Assume and fully perform all of Seller's duties, obligations,
and liabilities to individuals,  private entities, or governmental  authorities,
with  respect to the Assets to which Seller was a party or by which it was bound
on and  after the  Effective  Date,  including  duties,  liabilities,  and other
obligations imposed by any leases,  rights-of-way,  contracts,  bonds,  permits,
licenses,  and any other  instrument  to which Seller was a party or by which it
was bound to the extent such accrued on or after the effective date, and

               (C) Protect, defend, indemnify, and hold Seller harmless from any
and all Claims and Damages with respect

to the  foregoing  provisions of this  subsection  (i) except to the extent such
Claims or Damages arise from: (I) actions taken by Seller prior to the Effective
Date,  or (II) a failure of Seller to take  actions  required by Law or contract
prior to the Effective Date; provided further, that consistent with but not as a
limitation on the foregoing,  any and all obligations regarding the plugging and
abandonment of any wells on the Oil and Gas  Properties  shall be Buyer's rather
than Seller's obligation.

          (ii) At Seller's request, which may be made subsequent to the Closing,
Buyer shall promptly execute a document  confirming  Buyer's  assumption of such
duties,  liabilities,  and other  obligations under subsection (i), but Seller's
failure to request such a document shall not affect  Buyer's  assumption of such
duties, liabilities, and obligations.

          (iii) Notwithstanding subsections (i) or any other provision hereof to
the contrary,  responsibility for all Claims and Damages regarding environmental
matters shall be governed by Sections 6 and 14.

     13. Certain Adjustments.  (a) Appropriate adjustments shall be made between
         --------------------
Buyer and Seller so that:

          (i) all expenses  (including royalty,  overriding  royalty,  and other
payments based on production)  attributable  to Seller's  interest in the Assets
that are  incurred  in the  ownership  and  operation  of the Assets  before the
Effective  Date will be borne by Seller and all  proceeds  payable

                                       17

<PAGE>

to  Seller  for  its  interest  in the  Assets  (net of  applicable  production,
severance,  and  similar  taxes)  from the sale of oil,  gas and other  minerals
produced therefrom before the Effective Date will be received by Seller, and

          (ii) all  expenses  attributable  to  Seller's  interest in the Assets
which are incurred in the ownership and operation of the Assets on and after the
Effective Date will be borne by Buyer and all proceeds payable to Seller for its
interest in the Assets (net of  applicable  production,  severance,  and similar
taxes) from the sale of oil, gas and other  minerals  produced  therefrom on and
after the Effective Date will be received by Buyer.

     (b) In making  the  adjustments  under  subsection  (a):  (i) oil which was
produced from the Oil and Gas Properties  and which was, on the Effective  Date,
stored in tanks located on the Oil and Gas Properties (or located  elsewhere but
used by Seller to store oil produced  from the Oil and Gas  Properties  prior to
delivery to oil  purchasers) and above pipeline  connections  shall be deemed to
have been produced before the Effective Date, and (ii) ad valorem taxes assessed
with respect to the taxing period in which the Effective Date falls,  regardless
of the basis on which such taxes are  computed,  shall be prorated  based on the
number of days in such  period  which  fall on each side of the  Effective  Date
(with the day on which the  Effective  Date  falls  being  counted in the period
after the Effective Date), and shall, where the current year's taxes are not yet
known,  be based on the  previous  year's  taxes.  Each party shall bear its own
local, state or federal income tax liabilities.

     (c) As soon as practicable  after  Closing,  but in any event within ninety
(90) days  thereafter,  Seller  shall  prepare  and  submit to Buyer a  proposed
statement  ("Final  Statement"),  which shall show the final  calculation of the
Purchase Price ("Final  Settlement  Price"),  based on the adjustments for which
this  Agreement  provides.  As soon  as  possible  after  receipt  of the  Final
Statement, but in any event within thirty (30) days after receipt thereof, Buyer
shall deliver to Seller a written report  containing the changes,  if any, which
Buyer proposes being made to the Final  Statement;  provided  however,  if Buyer
fails to  timely  deliver  such  report,  Seller's  Final  Statement  and  Final
Settlement Price shall conclusively be deemed accurate, and such Final Statement
shall be the basis for the  Final  Settlement  Price.  In the event  that  Buyer
submits a response,  the parties shall exercise all reasonable  efforts to agree
with  respect  to the  amounts  due not later  than  ninety  (90) days after the
Closing,  but in any event prior to September 1, 2000.  After  agreement  upon a
Final  Settlement  Price  setting  forth the amount by which the Purchase  Price
shall be  adjusted  (either  upward or  downward),  the amount due shall be paid
within  five  (5)  business  days  thereafter  by the  party  owing  the same in
immediately  available funds.  Amounts due and payable hereunder,  but which are
not paid when due,  shall bear interest at the rate of one and one-half  percent
per month, compounded monthly, or the maximum amount permitted by law, whichever
is less.

     14. Environmental  Indemnity and Hazardous Substances.  (a) Notwithstanding
         --------------------------------------------------
anything herein to the contrary  except  subsection (c), with respect to the Oil
and Gas Properties,  upon Closing, Buyer: (i) waives, releases, remises, acquits
and  forever   discharges,   (ii)  releases  and   relinquishes   any  right  of
contribution,  reimbursement,  indemnification,  or other  rights  of a  similar
nature,  (iii)  assumes  all  liability  for,  and (iv) shall  protect,  defend,
indemnify,  and hold harmless,  Seller and its affiliates,  and their employees,
agents,  successors and assigns, from and with respect to any and all Claims and
Damages  (including  Corrective Action Costs (hereinafter  defined),  monitoring
costs (including  reasonable capital and operating costs),  remediation studies,
and natural

                                       18

<PAGE>

resource  damages)  that may at any  time  arise on  account  of,  or in any way
arising out of, or in connection  with:  (I) the known or unknown  environmental
condition of the Oil and Gas  Properties,  including  any Releases  (hereinafter
defined), and (II) any violation of any federal,  state, or local law (including
statutory and case law), rule, regulation,  ordinance,  permit,  license, order,
judgment,  injunction,  writ,  or  decree  of any  nature  (collectively  "Law")
relating  to the  protection  of  health  or  the  environment,  whether  or not
attributable  to  Seller's  activities  or  the  activities  of  third  parties,
regardless  of whether or not  Seller  was or is aware of such  activities,  and
regardless of whether or not the condition  (including any Release) or violation
occurred before or after the Effective Date.

     (b) As used in this Agreement, the following definitions shall apply:

          (i) "Hazardous  Substances" means any substance or material defined or
designated as hazardous or toxic waste,  hazardous or toxic material,  hazardous
or  toxic  substance,  or  other  similar  term,  by  any  Law  relating  to the
environment  (which Laws include the Federal Resource  Conservation and Recovery
Act of 1976; Federal Comprehensive  Environmental  Response,  Compensation,  and
Liability Act of 1980;  Federal Clean Air Act;  Federal Clean Water Act; Federal
Water Pollution  Control Act; Federal  Insecticide,  Fungicide,  and Rodenticide
Act;  and similar  state Laws in effect as of the relevant  dates,  as such Laws
were or are amended from time to time).

          (ii)  "Releases"  means  any  spilling,   leaking,  pumping,  pouring,
emitting, emptying,  discharging,  injecting,  depositing,  releasing, escaping,
leaching,   dumping  or  disposing  of  Hazardous  Substances  or  non-hazardous
substances  (to the extent the Law  requires  the  removal of the same) into the
atmosphere,  soil, surface water, subsurface strata,  groundwater,  or otherwise
into the  environment,  including  the  abandonment  or  discarding  of barrels,
containers,  tanks,  or other  receptacles  containing or previously  containing
Hazardous Substances.

          (iii)  "Corrective  Action" means,  to the extent required by Law, any
expenditures or activities taken to monitor and, if required,  abate,  clean up,
remove,  treat,  cover or in any other way  remediate  a Release  at,  from,  or
emanating to the Oil and Gas Properties.

          (iv)  "Corrective  Action  Costs"  includes  any and all: (A) costs or
expenses  that arise  directly  from or in connection  with the  performance  of
Corrective  Action,  including  removal,  remediation  or  cleanup  costs,  site
investigation and assessment costs, consultants costs, attorneys fees and expert
fees,  government  oversight and response costs,  penalties,  liens,  interests,
fines,  assessments,  and charges, and (B) any payment of any third party Claims
or Damages (including any federal, state or local government agency) arising out
of or relating to a Release at or from the Oil and Gas Properties.

     (c)(i) If Buyer  within one (1) year after the  Closing:  (A)  discovers  a
violation of an environmental Law that occurred prior to the Effective Date with
respect to any Oil and Gas  Property  and such  violation  was not  disclosed by
Seller to Buyer prior to the Closing,  (B) notifies  Seller (such that notice is
actually  received  by Seller  within  said one (1) year  period) in  reasonable
detail  of the Law that  was  violated  and the  manner  in  which  such Law was
violated,  (C) includes with such notice sufficient  information to substantiate
the violation of such Law, and (D) includes in such notice a reasonable range of
alternative  dates and times for  scheduling a meeting in Denver,  Colorado,  to
take

                                       19

<PAGE>

place within two weeks after the notice was given, to discuss how to address the
violation,  then the  provisions of subsections  (ii) and (iii) shall apply.  No
notice  shall be  effective  unless it complies  with  clauses (A) - (D) of this
subsection.  Buyer shall have the burden of proving that such violation occurred
prior to the  Effective  Date and was not  disclosed by Seller to Buyer prior to
the Closing.

          (ii) At the meeting  referenced in  subsection  (i), the parties shall
discuss  how to remedy the  violation.  Such  approaches  may  include:  (A) the
performance  by  Seller  of  Corrective  Action,  and the  payment  by Seller of
Corrective  Action Costs,  to remedy the  violation,  or (B) the  performance by
Buyer of Corrective Action, and the payment by Buyer of Corrective Action Costs,
coupled with an adjustment in the Purchase Price, and with Buyer otherwise being
responsible  for the violation in accordance  with subsection (a) without regard
to this subsection (c).

          (iii)(A)  If within  sixty  (60) days  following  Seller's  receipt of
Buyer's notice the parties cannot agree on how to remedy the violation specified
in the notice, this Agreement shall be rescinded as to each Oil and Gas Property
as to which the parties  were unable to so agree.  Consistent  with but not as a
limitation on the foregoing,  in such event, and within said 60 day period:  (I)
Buyer  shall  reconvey  each  such Oil and Gas  Property  to Seller by a special
warranty  conveyance,  with such  conveyance to be effective as of the Effective
Date,  (II)  Buyer  shall  account  for  and pay to  Seller  all  proceeds  from
production (net of reasonable expenses) attributable to the period subsequent to
the Effective Date,  provided however,  if and to the extent any such production
was not sold in an arm's length  transaction at generally  prevailing prices for
like  production  from the  Williston  Basin,  the amount to be paid by Buyer to
Seller shall be an amount equal to that which would have been received in such a
transaction,  and (III) Seller shall pay Buyer an amount equal to the  Allocated
Value. Notwithstanding the rescission,  however, Seller shall not be required to
pay Buyer for any capital  improvements made by or on behalf of Buyer to the Oil
and Gas  Property.  Neither  party  shall be  obligated  to pay the other  party
interest (which shall be at the rate specified in Section 13) on amounts owed to
the other party, if such amounts owed are paid within said 60 days.

               (B)  As to  any  Oil  and  Gas  Property  reconveyed  under  this
subsection, Buyer shall grant Seller, without any

further  consideration,  any and all  easements  and  rights-of-way  that may be
necessary or reasonably  convenient  for Seller to access or perform  Corrective
Action with regard to such property.

     (d) Nothing  herein  shall limit a party's  right to seek  contribution  or
reimbursement  from any  non-affiliated  third party who may be responsible  for
Corrective  Action  or  Corrective  Action  Costs,  or for any  other  Claims or
Damages.

     15.  Commissions.  Seller shall  indemnify and hold Buyer harmless from and
          ------------
against any and all Claims and  Damages  arising  out of or  resulting  from any
agreement,  arrangement  or  understanding  alleged  to have been made by, or on
behalf of, Seller with any broker or finder in connection with this Agreement or
the  transaction  contemplated  hereby,  and (b). Buyer shall indemnify and hold
harmless  Seller from and against any and all Claims and Damages  arising out of
or resulting from any agreement,  arrangement or  understanding  alleged to have
been made by, or

                                       20

<PAGE>

on behalf of, Buyer with any broker or finder in connection  with this Agreement
or the transaction contemplated hereby.

     16.  Casualty Loss. In the event of damage by fire or other casualty to the
          --------------
Assets  prior to the  Closing,  this  Agreement  shall  remain in full force and
effect, and in such event, unless Buyer and Seller shall otherwise agree:

     (a) as to each such Asset so damaged  that is an Oil and Gas  Property,  at
Buyer's election  either:  (i) such Asset shall be treated as if it were subject
to an Asserted  Defect,  and the  procedure  provided  for in Section 6 shall be
applicable  thereto,  or (ii) the Purchase  Price will not be  adjusted,  but if
Seller is entitled to make any claims under any insurance policy with respect to
such  damage,  Seller  shall,  at Seller's  election,  either  collect (and when
collected,  or at the Closing,  whichever  last occurs,  pay over to Buyer),  or
assign  to Buyer  (at the  Closing)  (subject  to  Buyer's  review  of  Seller's
insurance policy relating to the loss), such claims, and

     (b) as to each such Asset so damaged  that is not an Oil and Gas  Property,
at Seller's election it shall either collect for (and when collected,  or at the
Closing,  whichever last occurs,  pay over to Buyer), or assign to Buyer (at the
Closing), subject to Buyer's review of Seller's insurance policy that relates to
the loss,  any and all insurance  claims  relating to such loss, and Buyer shall
take title to the Asset affected by such loss without  reduction of the Purchase
Price.

     17. Notices. All notices, demands or communications  ("Notices") under this
         --------
Agreement  shall be in writing and shall be  addressed to the party as set forth
below.  All Notices shall be given by: (i) personal  delivery,  (ii)  electronic
communication,  provided  the  transmitting  device  used by the Party  provides
documentary confirmation of receipt, (iii) first class mail, postage prepaid, or
(iv) a nationally  recognized  overnight  courier service.  All Notices shall be
effective  and shall be  deemed  delivered  (i) if by  personal  delivery  or by
overnight  courier,  on the date of delivery if delivered on or before 4:30 p.m.
on such day;  otherwise,  it shall be deemed to have been  delivered on the next
business day following delivery, (ii) if by electronic communication, on the day
of receipt unless received after 4:30 p.m., in which event it shall be deemed to
have been received on the next business day following  receipt of the electronic
communication,  and  (iii) if  solely  by mail,  on the first to occur or actual
receipt. A party may change its address by Notice to the other party.

If to Seller:

         Tipperary Oil & Gas Corporation
         633 17th Street, Suite 1550
         Denver, Colorado   80202
         Attention: Jeff T. Obourn
         Telephone No: (303) 293-9379
         Facsimile No.:  (303) 292-3428

                                       21

<PAGE>

If to Buyer:

         Nance Petroleum
         P.O. Box 7168
         Billings, Montana   59103
         Attention: Ron Santi
         Telephone No: (406) 245-6248
         Facsimile No.:  (406) 245-9106

     18. Survival of Provisions.  The parties' respective  covenants  (including
         -----------------------
indemnification  obligations) that are to be performed after the Closing or that
may otherwise be applicable  following the Closing,  and the parties' respective
warranties and representations (and disclaimers of warranties,  representations,
and  covenants),  shall  survive  the  Closing  and  shall  not  merge  into the
Assignment  or into  any  other  documents  or  other  instruments  executed  in
connection herewith.  Consistent with, but not as a limitation on the foregoing,
the parties' respective obligations under Sections 6(a)(iii) and 7(a)(ii)(E) (to
the extent the same are, by mutual  agreement,  not  performed at Closing),  and
Sections 2(c), 3, 4, 5(c)(ii),  6(b)(i)(A), 6(e), 8, 11(c), 12(d), 12(e), 12(h),
13(c),  14, 15, 17, 18, 20 - 27, 30, and 32 shall  survive  the  Closing and the
delivery of the Assignment.

     19.  Operations.  Subject  to the  terms  and  provisions  of any  existing
          -----------
agreements covering the Assets, Seller agrees to turn over to Buyer, at Closing,
the  operations  of those Assets for which it is currently  serving as operator.
Seller shall take all reasonable  actions necessary to attempt to cause Buyer to
become successor operator as contemplated herein.

     20.  Confidentiality   Agreement.   The  Confidentiality   Agreement  shall
          ----------------------------
terminate  only if and after Closing  occurs and the  Assignment is executed and
delivered.

     21. Further  Assurances.  Without further  consideration,  each party shall
         --------------------
take  such  further  actions  and  execute  such  further  documents  as  may be
reasonably  requested by the other party in order to effectuate  the purpose and
intent  of this  Agreement,  including  (if  Closing  occurs)  division  orders,
transfer orders and other documents.

     22.  Governing Law, and Venue.  (a) This Agreement  shall be: (i) deemed to
          -------------------------
have been negotiated,  executed, and performed in Colorado, and (ii) governed by
and  interpreted in accordance  with the laws of Colorado,  except to the extent
its laws would otherwise apply the laws of another jurisdiction.

     (b)  Exclusive  venue for the  resolution  of any disputes  regarding  this
Agreement shall be in a state or federal court of competent jurisdiction sitting
in Colorado.  If and to the extent  Buyer does not have a  registered  agent for
service of process in Colorado, then for purposes hereof, service of process may
be accomplished in the manner of service upon the Colorado Secretary of State or
in such other  manner as may be provided by law for  service  upon  corporations
that are required to have a registered  agent in Colorado but that do not have a
registered agent.

                                       22

<PAGE>

     23. Costs. Except as may be expressly provided otherwise herein, each party
         ------
shall bear its own costs and expenses in  connection  with the  negotiation  and
performance of this Agreement.

     24. Entire  Agreement;  Amendment;  and Waiver.  (a) This Agreement,  which
         -------------------------------------------
includes any and all exhibits,  contains the entire  understanding and agreement
of the parties and supersedes all prior  agreements and  understandings  between
the parties relating to the subject matter hereof.

     (b) No  amendment  or  modification  to this  Agreement  shall be effective
unless be in writing and signed by all parties.

     (c) No waiver by a party of any breach by the other party of any  provision
of this Agreement shall be deemed a waiver of any preceding or succeeding breach
of the same or any other  provisions  hereof.  No such waiver shall be effective
unless in writing and then only to the extent expressly set forth in writing.

     25. Section and Other  Headings;  and  Construction.  The section and other
         ------------------------------------------------
headings  contained in this  Agreement are for reference  only and have no legal
significance.  The use of  pronouns is generic and they shall mean any gender as
appropriate.  The terms "include",  "including," or similar terminology shall be
construed  as  meaning  without  limitation  as to the  nature  or  scope of the
referenced  matters.  The terms  "herein" or "hereof,"  or similar  terminology,
shall be construed as referring to this  Agreement  rather than only the section
in which such term appears. References to subsections shall refer to the section
or subsection in which they appear, unless otherwise noted. This Agreement shall
be deemed to have been drafted by both  parties,  and therefore the rule against
construing   ambiguities   against  the  party  drafting  a  contract  shall  be
inapplicable to this Agreement.

     26. Severability.  If any provision of this Agreement is held to be invalid
         -------------
or  unenforceable  in  whole  or in  part  in any  relevant  jurisdiction,  such
provision, only to the extent invalid or unenforceable,  shall be severable from
this  Agreement,  and the other  provisions  of this  Agreement  (along with the
provision at issue,  to the extent that it would be valid and  enforceable,  and
such provision shall be deemed to be so reformed) shall remain in full force and
effect  in such  jurisdiction  and the  remaining  provisions  hereof  shall  be
liberally  construed to carry out the purpose and intent of this Agreement.  The
invalidity  or  unenforceability,  in whole or in part, of any provision of this
Agreement  in any  relevant  jurisdiction  shall  not  affect  the  validity  or
enforceability  of such  provision  in any  other  jurisdiction,  nor  shall the
invalidity or  unenforceability  of any provision of this Agreement with respect
to any Person  affect the  validity or  enforceability  of such  provision  with
respect to any other Person.

     27.  Attorney's Fees. If litigation is commenced  between the parties,  the
          ----------------
prevailing  party  shall be  entitled  to  recover  from  the  other  party  all
reasonable  attorney fees and costs. The prevailing party shall include: a party
who  dismisses  an action in  exchange  for sums  allegedly  due;  the party who
received performance from the other party for an alleged breach of contract or a
desired remedy where the performance is substantially equal to the relief sought
in an action;  or the party  determined to be the prevailing party by a court of
law.

                                       23

<PAGE>

     28.  Restrictions on Assignment.  Neither party may assign its rights under
          ---------------------------
this Agreement and any such  assignment in violation of this provision  shall be
void; provided however,  that  notwithstanding the foregoing,  Seller may assign
its rights under this  Agreement to a subsidiary or other  affiliate  subject to
Buyer's approval, which may not be unreasonably withheld.

     29. Time of the Essence.  Time is of the essence of this Agreement.  If the
         --------------------
last day permitted for the  performance  of any act required or permitted  under
this  Agreement  falls on a  Saturday,  Sunday,  or  holiday,  the time for such
performance shall be extended to the next succeeding business day.

     30. Parties in Interest;  Successors and Assigns.  This Agreement  shall be
         ---------------------------------------------
binding upon and inure to the benefit of and be  enforceable  by the  successors
and permitted assigns of Seller or Buyer.  Nothing in this Agreement is intended
to confer  upon any other  person or entity any rights or  remedies  under or by
reason of this Agreement.

     31. No  Publicity.  Prior to closing,  neither Buyer nor Seller shall issue
         --------------
any  publicity or press release  concerning  this  Agreement or the  transaction
contemplated  hereby without the other party's prior written consent unless,  in
the written  opinion of a party's legal counsel,  such disclosure is required by
applicable law or other  applicable  rules or  regulations  of any  governmental
authority or stock exchange and such publicity or press release contains no more
than the minimum information necessary to comply therewith. This provision shall
not replace or restrict any provision in any prior agreement between the parties
affecting confidentiality or the disclosure of information about the Assets.

     32. No  Recording.  This  Agreement  shall not be recorded by either  party
         --------------
without the prior consent of the other party.


         IN WITNESS WHEREOF, this Agreement is executed by the parties hereto on
the date set forth above.

SELLER:                                          BUYER:

TIPPERARY OIL & GAS CORPORATION                  NANCE PETROLEUM CORPORATION


By:/s/ DAVID L. BRADSHAW                         By:/s/ ROBERT L. NANCE
   ---------------------                            -------------------
Name:  David L. Bradshaw                         Name:  Robert L. Nance
Title: President & CEO                           Title: President & CEO

                                       24

<PAGE>

                                                     Purchase and Sale Agreement
                                         Between TIPPERARY OIL & GAS CORPORATION
                                                 and NANCE PETROLEUM CORPORATION

                                   EXHIBIT "C"
                                   -----------

                           ASSIGNMENT AND BILL OF SALE
                           ---------------------------

     THIS ASSIGNMENT AND BILL OF SALE  ("Assignment"),  dated April 28, 2000, is
between Tipperary Oil & Gas Corporation,  a Texas corporation ("Assignor"),  the
address of which is 633 17th Street,  Suite 1550,  Denver,  Colorado 80202,  and
Nance Petroleum Corporation, a Montana corporation ("Assignee"),  the address of
which is 550 North 31st Street, Suite 500, Billings, Montana 59101.

                                    RECITALS:

     A. The parties entered into that certain  Purchase and Sale Agreement dated
April   10,  2000  ("Agreement"),  pursuant  to which  Assignor  agreed to sell,
assign,  and convey,  and Assignee agreed to purchase the hereinafter  described
Assets.

     B. The  parties  have  consummated  the  purchase  and  sale of the  Assets
pursuant to the Agreement,  and this  Assignment is being executed and delivered
pursuant thereto.

     NOW  THEREFORE,  for good  and  valuable  consideration,  the  receipt  and
sufficiency of which are hereby acknowledged, the parties agree as follows:

     1. Conveyance and Reservation.  (a) Assignor does hereby sell,  assign, and
convey unto Assignee the following described  properties,  rights and interests,
but only to the  extent  related  to the real  property  described  in Exhibit A
("Property"):

          (i) All of Assignor's right, title, and interest,  if any, in all oil,
gas  and  other  mineral  interests,  including  Assignor's  right,  title,  and
interest,  if any, in all: (A) oil and gas leases and any other mineral  leases,
(B) royalties and overriding royalties, (C) production payments, (D) net profits
interests,  (E) reversionary  mineral interests,  (F) unitization,  pooling, and
communitization agreements, and (G) declarations and orders (including all units
formed under orders, rules, regulations,  or other official acts of any federal,
state,  or  other  authority  having  jurisdiction,  and  voluntary  unitization
agreements,  designations  and  declarations),  subject  to any  exceptions  and
reservations contained in Exhibit A;

          (ii) All of Assignor's  right,  title,  and  interest,  if any, in all
fixtures,  equipment, and other personal property, to the extent relating to the
wells  described  in  Exhibit  B  and  their  appurtenant  production,  storage,
treating,  gathering, and transportation  facilities,  situated on the Property;
and

          (iii) all  contracts;  lease  files;  abstracts  and  title  opinions;
production records;  well files;  permits and licenses;  accounting records (but
excluding all general financial accounting or tax

                                       1

<PAGE>

accounting  records that do not pertain  exclusively to the Property);  electric
logs and geological,  engineering, and other technical data and records (subject
to any contractual or other  restrictions  relating to the transfer of such data
and records); and other files, documents and records that directly relate to the
Property.

     (b) Assignor's interest,  if any, in the assets described in subsection (a)
is herein sometimes collectively called the "Assets."

     (c) Assignor excepts and reserves from this  Assignment,  and reserves unto
itself,  all of its right,  title,  and interest in and to the surface estate of
the  Property  (to the extent of any  surface  estate  interests  not created by
lease,  easement,  or  right-of-way)  and all  rights of any  nature  whatsoever
appurtenant  or  otherwise  associated  therewith,  and such right,  title,  and
interest does not constitute any part of the Assets; provided however,  Assignor
grants  Assignee  the right to use the  surface  of the  Property  for  purposes
reasonably  necessary or incidental  to oil and gas  operations on the Property,
but Assignee shall protect,  defend,  indemnify, and hold Assignor harmless from
and against  any and all Claims  (hereinafter  defined) or Damages  (hereinafter
defined) resulting from such use.

     (d) Except for: (i) easements and rights-of-way of record, (ii) other third
party rights (if any) that could not reasonably be expected to have a materially
adverse  affect  on the  use of the  Assets,  and  (iii)  liens  for  taxes  and
assessments  due but not yet  payable,  Assignor  warrants  title to the  Assets
against  anyone  claiming any interest  therein  arising by,  through,  or under
Assignor,  but Assignor makes no other  warranty,  representation,  or covenant,
express or implied, statutory or otherwise, as to title to the Assets.

     (e) As of the  effective  date hereof,  Assignee  assumes all of Assignor's
duties, liabilities and obligations relating to the Assets to which Assignor was
a party or by which  it was  bound on and  after  the  date  hereof,  and  shall
protect,  defend,  indemnify, and hold Assignor harmless from any and all Claims
and Damages  with respect  thereto,  except to the extent such Claims or Damages
arise from: (i) actions taken by Assignor prior to the effective date hereof, or
(ii) a failure of Assignor to take actions required by Law (hereinafter defined)
or contract prior to the effective date hereof.

     2. Disclaimer of Warranties. (a) Except as provided in Section 1(d) hereof,
Assignor makes no warranty,  representation, or covenant, express or implied, as
to  its  title  to  the  Assets,   and   Assignor   makes  no  other   warranty,
representation, or covenant, express or implied, with respect to the Assets.

     (b) CONSISTENT  WITH AND NOT AS A LIMITATION ON SUBSECTION  (a), THE ASSETS
ARE  HEREBY  PURCHASED,  SOLD,  AND  CONVEYED  "AS IS,  WHERE IS",  WITHOUT  ANY
WARRANTY,   REPRESENTATION,  OR  COVENANT,  EXPRESS  OR  IMPLIED,  STATUTORY  OR
OTHERWISE, RELATING TO:

          (i) THE CONDITION, QUANTITY, QUALITY, FITNESS FOR A PARTICULAR PURPOSE
OR  ANY  PURPOSE,   CONFORMITY  TO  THE  MODELS  OR  SAMPLES  OF  MATERIALS,  OR
MERCHANTABILITY  OF  ANY  IMMOVABLE  PROPERTY,   MOVABLE

                                       2

<PAGE>

PROPERTY,  EQUIPMENT,  INVENTORY,  MACHINERY,  AND OTHER  FIXTURES  AND PERSONAL
PROPERTY CONSTITUTING PART OF THE ASSETS;

          (ii) ANY IMPLIED OR EXPRESS WARRANTY OF FREEDOM FROM REDHIBITORY VICES
OR DEFECTS OR OTHER VICES OR DEFECTS, WHETHER KNOWN OR UNKNOWN; AND

          (iii) ANY AND ALL IMPLIED  WARRANTIES,  REPRESENTATIONS,  OR COVENANTS
EXISTING UNDER APPLICABLE LAW NOW OR HEREAFTER IN EFFECT.

     (c) CONSISTENT WITH BUT NOT AS A LIMITATION ON SUBSECTIONS (a) AND (b):

          (i)  ASSIGNOR  IS SELLING  AND  ASSIGNEE IS BUYING THE ASSETS WITH ALL
DEFECTS AND FAULTS  (LATENT OR  APPARENT)  AND IT ASSUMES THE RISK THAT  ADVERSE
PAST,  PRESENT OR FUTURE  PHYSICAL  CONDITIONS MAY NOT HAVE BEEN REVEALED BY ITS
INVESTIGATIONS, AND

          (ii) ASSIGNOR MAKES NO WARRANTY OR REPRESENTATION, EXPRESS OR IMPLIED,
STATUTORY OR OTHERWISE, AS TO THE ACCURACY OR COMPLETENESS OF ANY DATA, REPORTS,
RECORDS,  PROJECTIONS,  INFORMATION,  OR  OTHER  MATERIALS  NOW  HERETOFORE,  OR
HEREAFTER  FURNISHED  OR MADE  AVAILABLE  TO  ASSIGNEE IN  CONNECTION  HEREWITH,
INCLUDING PRICING ASSUMPTIONS OR QUALITY OR QUANTITY OF HYDROCARBON RESERVES (IF
ANY)  ATTRIBUTABLE  TO THE ASSETS OR THE ABILITY OR  POTENTIAL  OF THE ASSETS TO
PRODUCE  HYDROCARBONS OR THE ENVIRONMENTAL  CONDITION OF THE ASSETS OR ANY OTHER
MATERIALS FURNISHED OR MADE AVAILABLE TO ASSIGNEE BY OR ON BEHALF OF ASSIGNOR.

     3. Environmental  Indemnity and Hazardous  Substances.  (a) Notwithstanding
anything  herein to the  contrary,  with  respect to the Assets,  Assignee:  (i)
waives,  releases,  remises,  acquits and forever discharges,  (ii) releases and
relinquishes any right of contribution, reimbursement, indemnification, or other
rights of a similar  nature,  (iii)  assumes all  liability  for, and (iv) shall
protect, defend, indemnify, and hold harmless,  Assignor and its affiliates, and
their employees,  agents,  successors and assigns,  from and with respect to any
and all rights, claims, demands, causes of action, and legal, administrative, or
arbitration proceedings,  of any and every nature (collectively,  "Claims"), and
injuries, deaths, damages, or obligations of any and every nature resulting from
or that gave rise to any Claim, including liabilities, losses, costs, penalties,
expenses,  judgments, fines, settlements,  interest, reasonable attorney's fees,
Corrective  Action Costs  (hereinafter  defined),  monitoring  costs  (including
reasonable  capital  and  operating  costs),  remediation  studies,  and natural
resource  damages  and  other  related  expenses  of any  nature  (collectively,
"Damages")  (provided  however,  that Damages  shall not include  consequential,
special,  incidental, or punitive damages) that may at any time arise on account
of,  or in any way  arising  out of,  or in  connection  with:  (I) the known or
unknown   environmental   condition  of  the  Assets,   including  any  Releases
(hereinafter  defined),  and (II) any violation of any federal,  state, or local
law (including  statutory and case law), rule,  regulation,  ordinance,  permit,
license,   order,   judgment,

                                       3
<PAGE>


injunction,  writ, or decree of any nature  (collectively "Law") relating to the
protection  of  health  or  the  environment,  whether  or not  attributable  to
Assignor's activities or the activities of third parties,  regardless of whether
or not Assignor was or is aware of such activities, and regardless of whether or
not the condition  (including any Release) or violation occurred before or after
the effective date hereof.

     (b) As used herein, the following definitions shall apply:

          (i) "Hazardous  Substances" means any substance or material defined or
designated as hazardous or toxic waste,  hazardous or toxic material,  hazardous
or  toxic  substance,  or  other  similar  term,  by  any  Law  relating  to the
environment  (which Laws include the Federal Resource  Conservation and Recovery
Act of 1976; Federal Comprehensive  Environmental  Response,  Compensation,  and
Liability Act of 1980;  Federal Clean Air Act;  Federal Clean Water Act; Federal
Water Pollution  Control Act; Federal  Insecticide,  Fungicide,  and Rodenticide
Act;  and similar  state Laws in effect as of the relevant  dates,  as such Laws
were or are amended from time to time).

          (ii)  "Releases"  means  any  spilling,   leaking,  pumping,  pouring,
emitting, emptying,  discharging,  injecting,  depositing,  releasing, escaping,
leaching,   dumping  or  disposing  of  Hazardous  Substances  or  non-hazardous
substances  (to the extent the Law  requires  the  removal of the same) into the
atmosphere,  soil, surface water, subsurface strata,  groundwater,  or otherwise
into the  environment,  including  the  abandonment  or  discarding  of barrels,
containers,  tanks,  or other  receptacles  containing or previously  containing
Hazardous Substances.

          (iii)  "Corrective  Action" means,  to the extent required by Law, any
expenditures or activities taken to monitor and, if required,  abate,  clean up,
remove,  treat,  cover or in any other way  remediate  a Release  at,  from,  or
emanating to the Assets.

          (iv)  "Corrective  Action  Costs"  includes  any and all: (A) costs or
expenses  that arise  directly  from or in connection  with the  performance  of
Corrective  Action,  including  removal,  remediation  or  cleanup  costs,  site
investigation and assessment costs, consultants costs, attorneys fees and expert
fees,  government  oversight and response costs,  penalties,  liens,  interests,
fines,  assessments,  and charges, and (B) any payment of any third party Claims
or Damages (including any federal, state or local government agency) arising out
of or relating to a Release at or from the Assets.

     (c)(i) If Assignee within one (1) year after the date hereof: (A) discovers
a violation of an  environmental  Law that occurred  prior to the Effective Date
hereof with  respect to any  Property and such  violation  was not  disclosed by
Assignor to Assignee prior to the date hereof,  (B) notifies Assignor (such that
notice is  actually  received by  Assignor  within said one (1) year  period) in
reasonable  detail of the Law that was violated and the manner in which such Law
was  violated,   (C)  includes  with  such  notice  sufficient   information  to
substantiate  the  violation  of such Law,  and (D)  includes  in such  notice a
reasonable  range of  alternative  dates and times for  scheduling  a meeting in
Denver,  Colorado, to take place within two weeks after the notice was given, to
discuss how to address the violation,  then the  provisions of subsections  (ii)
and (iii) shall  apply.  No notice shall be  effective  unless it complies  with
clauses (A) - (D) of this subsection.  Assignee shall have the burden

                                       4

<PAGE>


of proving that such  violation  occurred prior to the Effective Date hereof and
was not disclosed by Assignor to Assignee prior to the date hereof.

          (ii) At the meeting  referenced in  subsection  (i), the parties shall
discuss  how to remedy the  violation.  Such  approaches  may  include:  (A) the
performance  by Assignor of  Corrective  Action,  and the payment by Assignor of
Corrective  Action Costs,  to remedy the  violation,  or (B) the  performance by
Assignee of Corrective  Action, and the payment by Assignee of Corrective Action
Costs,  coupled with an  adjustment  in the purchase  price,  and with  Assignee
otherwise being  responsible for the violation in accordance with subsection (a)
without regard to this subsection (c).

          (iii)(A) If within  sixty (60) days  following  Assignor's  receipt of
Assignee's  notice  the  parties  cannot  agree on how to remedy  the  violation
specified in the notice,  this Agreement  shall be rescinded as to each Property
as to which the parties  were unable to so agree.  Consistent  with but not as a
limitation on the foregoing,  in such event, and within said 60 day period:  (I)
Assignee  shall  reconvey each such  Property to Assignor by a special  warranty
conveyance,  with such  conveyance  to be  effective  as of the  effective  time
hereof,  (II)  Assignee  shall account for and pay to Assignor all proceeds from
production (net of reasonable expenses) attributable to the period subsequent to
the  effective  time  hereof,  provided  however,  if and to the extent any such
production was not sold in an arm's length  transaction at generally  prevailing
prices for like  production from the Williston  Basin,  the amount to be paid by
Assignee  to  Assignor  shall be an amount  equal to that which  would have been
received in such a transaction,  and (III) Assignor shall pay Assignee an amount
equal to the Allocated Value, as defined in the Agreement.  Notwithstanding  the
rescission,  however,  Assignor  shall not be required to pay  Assignee  for any
capital  improvements made by or on behalf of Assignee to the Property.  Neither
party shall be obligated to pay the other party  interest on amounts owed to the
other party, if such amounts owed are paid within said 60 days.

               (B) As to any Property reconveyed under this subsection, Assignee
shall grant Assignor, without any further

consideration,  any and all easements and rights-of-way that may be necessary or
reasonably  convenient for Assignor to access or perform  Corrective Action with
regard to such property.

     (d) Nothing  herein  shall limit a party's  right to seek  contribution  or
reimbursement  from any  non-affiliated  third party who may be responsible  for
Corrective  Action  or  Corrective  Action  Costs,  or for any  other  Claims or
Damages.

     4. Subject to  Agreement.  This  Assignment  is subject to the terms of the
Agreement,  which terms are incorporated  herein by this reference,  survive the
execution  and  delivery of this  Agreement,  and are  binding on  Assignor  and
Assignee and their respective successors and assigns.

     5.  Counterparts.  This Assignment may be executed in several  counterparts
all of which are identical,  except that, to facilitate recordation,  in certain
counterparts  hereof,  only that  portion  of Exhibit A that  contains  specific
descriptions  of  assets  located  in the  recording  jurisdiction  in which the
particular  counterpart  is to be recorded are included,  and other  portions of
Exhibit A are included by reference only. All such  counterparts  together shall
constitute  one and the same  instrument.  Complete  copies  of this  Assignment
containing the entire Exhibit A have been retained by Assignor and Assignee.

                                       5

<PAGE>


     IN WITNESS WHEREOF,  this Assignment has been executed and delivered on the
date first set out above, but effective as to runs of oil and deliveries of gas,
and for all other purposes,  as of 7:00 a.m., local time at the locations of the
Assets, on March 1, 2000.

ASSIGNOR:                                        ASSIGNEE:

TIPPERARY OIL & GAS CORPORATION                  NANCE PETROLEUM CORPORATION


By:/s/ DAVID L. BRADSHAW                         By:/s/ ROBERT L. NANCE
   ---------------------                            -------------------
Name:  David L. Bradshaw                         Name:  Robert L. Nance
Title: President & CEO                           Title: President & CEO

                                       6

<PAGE>

                                        ASSIGNOR:

ATTEST:                                 TIPPERARY OIL & GAS CORPORATION

By:/s/ ELAINE R. TREECE                 By:/s/ JEFF T. OBOURN
   --------------------                    ------------------
Name:Elaine R. Treece                   Name:Jeff T. Obourn
Title:Corporate Secretary               Title:Sr. Vice President - Operations

                                        ASSIGNEE:

                                        NANCE PETROLEUM CORPORATION

                                        By:/s/ RONALD B. SANTI
                                           -------------------
                                        Name:Ronald B. Santi
                                        Title:Attorney in Fact


                                 ACKNOWLEDGMENTS

STATE OF COLORADO          )
                           ) ss
City and County of Denver  )

     On this 28th day of April,  2000, before me, a Notary Public of said state,
duly commissioned and sworn,  appeared David L. Bradshaw,  known to me to be the
person whose name is subscribed to the within  instrument as President and Chief
Executive Officer of TIPPERARY OIL & GAS CORPORATION,  a Texas corporation,  and
acknowledged to me that such corporation executed the same.

         Witness my hand and official seal.

                                              /s/ MICHELLE R. S. SULLIVAN
                                              ---------------------------
                                              Michelle R. S. Sullivan
                                              Notary Public, State of Colorado

                                              My commission expires:12-19-02


STATE OF MONTANA            )
                            ) ss
County of Yellowstone       )

     On this 28th day of April,  2000, before me, a Notary Public of said state,
duly  commissioned  and sworn,  appeared Robert L. Nance,  known to me to be the
person whose name is subscribed to the within  instrument as President and Chief
Executive Officer of NANCE PETROLEUM  CORPORATION,  a Montana  corporation,  and
acknowledged to me that such corporation executed the same.

         Witness my hand and official seal.

                                              /s/ STEVEN D. HART
                                              ------------------
                                              Steven D. Hart
                                              Notary Public, State of Montana

                                              My commission expires:6-28-00

                                       7

<PAGE>

                                                     Purchase and Sale Agreement
                                         Between TIPPERARY OIL & GAS CORPORATION
                                                 and NANCE PETROLEUM CORPORATION


                                   EXHIBIT "D"
                                   -----------

                               PREFERENTIAL RIGHTS
                               -------------------

NEGOTIATED WELLS WITH PREF RIGHTS IN THE JOA
--------------------------------------------

MONTANA
-------

BIDEGARAY B, C3 WSW
NORBY 2

RIDGELAWN DUPEROW UNIT
SHINY 30-42

SORENSEN B 1, C2, D3
STEINBEISSER A 3
WHITNEY A1, B2, C3


NORTH DAKOTA
------------

FELLAND, HELLEN E 1-30
GREEN, B A  #1-5
LINDVIG 10-21

NORBY, HENRY 1-20
SULLIVAN 3-29

                                       1

<PAGE>


                                                     Purchase and Sale Agreement
                                         Between TIPPERARY OIL & GAS CORPORATION
                                                 and NANCE PETROLEUM CORPORATION


                                  EXHIBIT "D-1"
                                  -------------

                              OFFICER'S CERTIFICATE
                              ---------------------

         TIPPERARY OIL & GAS CORPORATION,  a Texas corporation  ("Seller"),  the
address of which is 633 17th Street,  Suite 1550,  Denver,  Colorado 80202, with
respect  to that  certain  Purchase  and Sale  Agreement  dated  April 10,  2000
("Agreement"),  between  Seller  and  Nance  Petroleum  Corporation,  a  Montana
corporation ("Buyer"), hereby certifies that: (i) Seller has materially complied
with and performed all obligations  pertaining to Seller,  to be performed prior
to the  Closing,  except  for those  waived by Buyer,  and (ii) all of  Seller's
warranties and  representations  in the Agreement  remain true and correct as of
the date hereof, the same as if made as of the date hereof.

         Executed as of this 3rd day of May, 2000.

                                          SELLER:

                                          TIPPERARY OIL & GAS CORPORATION

                                          By:/s/ DAVID L. BRADSHAW
                                             ---------------------
                                             David L. Bradshaw
                                             President & Chief Executive Officer

                                       1

<PAGE>


                                                     Purchase and Sale Agreement
                                         Between TIPPERARY OIL & GAS CORPORATION
                                                 and NANCE PETROLEUM CORPORATION


                                  EXHIBIT "D-2"
                                  -------------

                              OFFICER'S CERTIFICATE
                              ---------------------

         NANCE  PETROLEUM  CORPORATION,  a Montana  corporation  ("Buyer"),  the
address  of which  is 550  North  31st  Street,  Suite  500,  Billings,  Montana
59101,with  respect to that certain  Purchase and Sale Agreement dated April 10,
2000 ( "Agreement"),  between Buyer and TIPPERARY OIL & GAS CORPORATION, a Texas
corporation  ("Seller"),  the address of which is 633 17th  Street,  Suite 1550,
Denver, Colorado 80202, hereby certifies that: (i) Buyer has materially complied
with and performed all obligations pertaining to Buyer, to be performed prior to
the  Closing,  except  for  those  waived  by  Seller,  and (ii) all of  Buyer's
warranties and  representations  in the Agreement  remain true and correct as of
the date hereof, the same as if made as of the date hereof.

         Executed as of this 3rd day of May, 2000.

                                          BUYER:
                                          NANCE PETROLEUM CORPORATION

                                          By:/s/ ROBERT L. NANCE
                                             -------------------
                                             Robert L. Nance
                                             President & Chief Executive Officer

                                       1

<PAGE>


                                                     Purchase and Sale Agreement
                                         Between TIPPERARY OIL & GAS CORPORATION
                                                 and NANCE PETROLEUM CORPORATION


                                   EXHIBIT "E"
                                   -----------

                              NON-FOREIGN AFFIDAVIT
                              ---------------------
                        Exemption from Withholding of Tax
                        ---------------------------------
                                       for
                                       ---
                  Dispositions of U.S. Real Property Interests
                  --------------------------------------------

     Section 1445 of the Internal  Revenue Code  provides that a transferee of a
U.S.  real property  interest  must withhold tax if the  transferor is a foreign
person.  To inform  Nance  Petroleum  Corporation  that  withholding  tax is not
required upon the disposition of U.S. real property interests by Tipperary Oil &
Gas Corporation, the undersigned hereby certifies the following:

1.   Tipperary  Oil &  Gas  Corporation  is  not a  nonresident  alien,  foreign
     corporation,  foreign  partnership,  foreign  trust,  or foreign estate for
     purposes of U.S. income tax;

2.   That  taxpayer  identifying  number of Tipperary Oil & Gas  Corporation  is
     75-1446759; and

3.   The office  address of the  financial  headquarters  of Tipperary Oil & Gas
     Corporation is 633 17th Street, Suite 1550, Denver, Colorado 80202.

     Tipperary Oil & Gas Corporation  understands that this certification may be
disclosed to the Internal Revenue Service by Nance Petroleum  Corporation or its
affiliates or parent,  and that any false  statement  contained  herein could be
punished by fine, imprisonment, or both.

     Under   penalties  of  perjury,   I  declare  that  I  have  examined  this
certification and, to the best of my knowledge and belief, it is true,  correct,
complete, and further declare I have authority to sign this document.

TIPPERARY OIL & GAS CORPORATION


By:/s/ DAVID L. BRADSHAW
   ---------------------
   David L. Bradshaw
   President & Chief Executive Officer

     SUBSCRIBED  AND SWORN TO by said  David L.  Bradshaw  before me this day of
May, 2000, to certify which witness my hand and seal of office.


                                  /s/ PHYLLIS KAJIWARA
                                  --------------------
                                  Phyllis Kajiwara
                                  Notary Public in and for the State of Colorado

                                  My commission expires:7-31-02

                                       1