# DEBENTURE
EXCHANGE SUBSCRIPTION AGREEMENT

This
Debenture Exchange Subscription Agreement (the Agreement) is
between the debenture holder identified on the signature page of this Agreement
(Subscriber), Republic Resources, Inc. (Republic)
and Harken Energy Corporation (Harken) and is made with
reference to the following agreed facts:

A.
The undersigned Subscriber is the holder of a 11% Convertible Debenture, due
April 15, 2003 (the Debenture) of Republic (formerly Pease
Oil and Gas Company) in the principal amount set forth on the signature page of
this Agreement.

B.
There are outstanding $2,645,500 of the Debentures held by Subscriber and other  holders
of the Debentures.

C.
Republic has agreed to sell to Harken, pursuant to a Purchase and Sale Agreement
dated January 31, 2002 (the Asset Sale Agreement), all of
Republics interests in its oil and natural gas properties located in the
states of Louisiana and Texas that have proved reserves as of
January 1, 2002. The properties to be sold include all of Republics
income-producing assets as of January 1, 2002. In exchange for these assets,
Harken will deliver at closing up to 2,645,500 shares of Harken common stock
that will be distributed to the Subscriber and other holders of the Debentures
on a pro-rata basis in full satisfaction of Republics principal obligation
under the outstanding Debentures.

D.
The number of shares of Harken Common Stock to be issued at the closing of the
Asset Sale Agreement will be determined by dividing the total principal amount
of Republics outstanding Debentures by the average reported closing price
for Harkens Common Stock for the 20 trading days ending on the day before
the Closing of the Asset Sale Agreement (hereafter the Common Stock Value
Per Share). However, under no circumstances shall the Common Stock Value
Per Share be less than $1.00.

E.
The completion of the sale of the Republic assets to Harken is contingent upon:
(i) the approval of the Asset Sale Agreement by stockholders of Republic at a
special meeting of stockholders to be called for that purpose, and (ii)
acceptance of the exchange offer described in this Agreement by the holders of
substantially all of the outstanding Debentures.

F.
The parties intend that this Agreement shall be irrevocable by Subscriber unless the
Asset Sale Agreement is not closed by at least June 1, 2002.

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G.
In addition to the proved oil and gas properties, Republic will also convey to
Harken the Companys interest in certain exploratory prospects in Jackson
County, Texas that have not been given any initial value in the contemplated
transaction. These exploratory prospects will be evaluated for additional value
at the end of 2003 using a Lookback formula as defined in the
P&S Agreement, and a future Lookback Payment may be made in
early 2004. The amount of any Lookback Payment will be contingent
on, among other things, future exploratory successes in the Jackson County
prospects, of which there can be no assurance. In addition, there can be no
assurance that the operators of those prospects will actually drill any wells on
the prospects by the end of the Lookback period (which is at the end of 2003)
and if so whether Harken will agree to participate in exploration of the
prospects since it will be under no obligation to do so. Accordingly, the amount
of any Lookback Payment, if any, cannot be reasonablely determined
at this time. In any case, Republic has agreed, upon closing of the Asset Sale
Agreement, to assign the contingent Lookback Payment to the former holders of
its Series C Redeemable Preferred Stock in connection with a restructuring of
that security. It is expressly understood that neither the Subscriber nor any
other holder of the Debentures will have any right, title or interest in the
contingent Lookback Payment regardless of its ultimate value, if any, and
regardless of whether it is ultimately assigned to the Series C Preferred
stockholders or retained by Republic.

IN
CONSIDERATION, of the covenants and agreements of the parties and other good
and valuable consideration, the receipt and sufficiency of which is hereby
acknowledged, the parties agree as follows:

1.
Agreement to Exchange.  Subscriber hereby agrees to exchange and surrender the  Debenture
held by Subscriber effective on the day of Closing of the Asset Sale Agreement.  In
exchange for surrender and cancellation of Subscriber's Debenture, the undersigned
Subscriber shall  receive the following:

| | (a)
Payment of all unpaid interest on Subscribers Debenture through the date
of the Closing, to be paid by Republic at such time as Subscribers
Debenture certificate is delivered to Republic for cancellation;
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | (b)
An amount of common stock of Harken determined by dividing the principal amount
of Subscribers Debenture by the Common Stock Value Per Share
determined as described above. The shares of Harken Common Stock shall be issued
effective as of the closing of the Asset Sale Agreement and shall be delivered
to Subscriber at such time as Subscribers Debenture certificate is
delivered to Republic for cancellation; and
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | (c)
an amount of Republic restricted common stock equal to 350 shares for each
$1000.00 of principal amount of Subscribers Debenture. Note:
Republic shall issue a total of 1,000,000 shares of its restricted common stock
if all holders of all outstanding Debentures agree to the Exchange described in
this Subscription Agreement. This includes up to 74,075 shares that would be
issued to Houlihan, Smith and Company, Inc. in connection with their services
rendered in connection with this exchange offer.
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | (d)
Republic shall pay the interest to Subscriber through the date of the Closing of
the Asset Sale Agreement and Subscribers Debenture shall be deemed
surrendered and canceled as of such date, subject only to delivery to Subscriber
of the Harken Common Stock in exchange for surrender of Subscribers
Debenture certificate.
| | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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2.
Irrevocable Subscription; Acceptance. Subscriber understands and
acknowledges that this subscription to exchange Subscribers Debenture in
the manner described in this Agreement is irrevocable by Subscriber unless
Republic and Harken have not closed the Asset Sale Agreement by June 1, 2002.
Acceptance of this subscription by Republic and Harken is subject to: (i)
approval of the Asset Sale Agreement by Republic stockholders, (ii) receipt of
Debenture Exchange Subscriptions from holders of at least 90% of the outstanding
principal amount of Republics Debentures (provided that Harken and
Republic may, in their discretion, waive this condition), and (iii) Closing of
the Asset Sale Agreement. Until and unless the foregoing conditions are
satisfied, Subscribers Debenture shall continue to earn interest and to
represent an obligation of Republic to Subscriber as described in the Debenture.

3.
Acknowledgment of Disclosures. Subscriber acknowledges the receipt of
Harkens Disclosure Memorandum dated February 19, 2002. Subscriber also
acknowledges receipt from Republic a letter dated January 11, 2002, together
with copies of Republics Quarterly Report on Form 10-QSB for the quarter
ended September 30, 2001, a copy of Republics Press Release dated February
8, 2002, and a copy of the Republics preliminary Information Statement
filed with the Securities and Exchange Commission on February 20, 2002.
Subscriber has also been given access to full and complete information regarding
Republic and Harken and has utilized such access to the Subscribers
satisfaction for the purpose of obtaining such information regarding Republic
and Harken as the Subscriber has reasonably requested; and, particularly,
Subscriber has been given reasonable opportunity to ask questions of, and
receive answers from, representatives of Republic and Harken concerning the
terms and conditions of the exchange offer described in this Agreement, the
business and affairs of Republic and of Harken and all additional information
requested by Subscriber to the extent it would be reasonably available.

Subscriber
acknowledges that Houlihan Smith & Company, Inc. (Houlihan) has
been retained by Republic to, among other things: (a) determine whether or not
the proposed Exchange Offer contemplated in this Agreement was be a reasonable
exchange for the holders of the Debentures, given the financial condition of the
Company and of Harken; (b) prepare a descriptive memorandum that describes the
proposed exchange offer for the Debentures; and (c) contact the Debenture
holders to explain the exchange offer, answer any questions and assist holders
in completing the required documentation. Subscriber acknowledges that Houlihan
and persons who may be associated with Houlihan will receive: (x) cash fees
totaling $24,000 (plus out-of-pocket expenses) for such services regardless of
the outcome of the exchange offer; and (y) up to 74,075 shares of Republic
common stock if the Asset Sale Agreement is completed and all of the Debenture
holders agree to the Exchange described in this Subscription Agreement.

4.
Investment Intent. Subscriber represents and warrants that the common
stock of Harken which will be issued upon completion fo the exchange described
in this Agreement will be held for the Subscribers own account and for
investment purposes only, and without the intention of reselling or
redistributing the same except as may be effected in compliance with the
registration requirements of the Securities Act of 1933, as amended
(Securities Act); Subscriber has made no agreement with others
regarding any of the securities to be obtained in the exchange and
Subscribers financial condition is such that it is not likely that it will
be necessary for Subscriber to dispose of any of such securities in the
foreseeable future. Subscriber further represents and agrees that if, contrary
to the foregoing intentions, Subscriber should later desire to dispose of or
transfer any of the Harken Common Stock received by Subscriber in the exchange
in any manner, Subscriber shall not do so unless and until (i) such securities
have been registered under the Securities Act and all applicable securities
laws; or (ii) Subscriber shall first deliver to Harken a written notice
declaring such holderss intention to effect such transfer and describe in
sufficient detail the manner and circumstances of the proposed transfer, which
notice shall be accompanied either by: (A) written opinion of legal counsel who
shall be reasonably satisfactory to Harken, which opinion shall be addressed to
Harken and reasonably satisfactory in form and substance to Harkens
counsel, to the effect that the proposed sale or transfer is exempt from the
registration provisions of the Securities Act and all applicable state
securities laws, or (B) a no-action letter from the Securities and
Exchange Commission to the effect that the transfer of the Harken Common Stock
without registration would not result in a recommendation by the staff of the
Commission that action be taken with respect thereto.

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5.
Residence of Subscriber. Subscriber represents and warrants that Subscriber is a
bona fide resident of, is domiciled in, and received the exchange offer and made the
decision to  exchange securities in the state or country of residence set out on the
signature page of this  Agreement.

6.
Subscriber is Accredited Investor. Subscriber acknowledges that at the
time the Debenture was initially acquired, and at the time that Republic and
Subscriber agreed to extend the maturity and otherwise modify the terms of the
Debentures in March 2001, Subscriber qualified as a Accredited Investor as
described in Rule 501 of Regulation D adopted by the United States Securities
and Exchange Commission under the Securities Act. Subscriber represents to
Republic and Harken that as of the date of this Agreement set forth on the
signature page below, Subscriber continues to qualify as an Accredited Investor.

7.
Acknowledgment of Certain Risks. Subscriber acknowledges that upon
Closing of the Asset Sale Agreement, Subscriber shall have exchanged the
Republic Debenture now held, a debt security of Republic, for Harken Common
Stock, an equity security in a different entity. Following the exchange Republic
shall have no obligation to Subscriber and Subscriber will, instead, hold an
equity investment in Harken with no assurance that he will be able to liquidate
the investment and no right to receive the existing principal amount of the
Debenture. Subscriber acknowledges that holding the Harken Common Stock involves
certain risks, some of which are summarized or referred to in the Harken
Disclosure Memorandum. Likewise, Subscriber acknowledges that continuing to hold
the Republic Debenture would involve risk to Subscriber and other holders of the
Debentures, some of which are summarized in the information furnished to
Subscriber as summarized or described above. Subscriber is accepting the
exchange offer described in this Agreement notwithstanding such risks.

8.
No Tax Advice. Subscriber acknowledges that an exchange of
Subscribers Debenture for Harken Common Stock as described in this
Agreement is likely to be deemed to be a taxable transaction to Subscriber.
Subscriber is likely to have taxable gain or loss equal to the difference
between Subscribers tax basis in the Debenture and the fair market value
of the Harken Common Stock to be received in the exchange. While it is expected
that the fair market value of the Harken Common Stock is likely to be
approximately equal to the principal balance of the Debenture, Republic and
Harken have made no representations to Subscriber as to the tax implications to
Subscriber from the exchange described in this Agreement and Subscriber has been
advised to seek his own tax counsel regarding the exchange. Subscriber has
received, from Subscribers own tax or other advisors, all information
Subscriber requires concerning the tax consequences of the exchange described in
this Agreement and has not, and does not, rely upon Republic or Harken with
respect to tax implications of the exchange.

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9.
No Transfer or Assignment. Neither this Agreement nor any of the rights of
Subscriber, Republic or Harken may be transferred or assigned by any party.  This
Agreement shall  survive the death or disability of Subscriber and shall be binding upon
Subscriber's heirs, executors,  administrators, successors and attempted assigns.

10.
Arbitration of Disputes. In the event that a dispute arises between
Subscriber and Republic or Harken arising out of or in connection with exchange
by Subscriber of the Debenture for Harken Common Stock, Subscriber, Republic and
Harken hereby expressly agree that such dispute shall be resolved through
arbitration rather than litigation. The undersigned hereby agrees to submit the
dispute to binding arbitration through the American Arbitration Association
(AAA) in Denver, Colorado, to be conducted in accordance with the
rules of commercial arbitration adopted by AAA. Such a dispute shall be
submitted to arbitration by any party by filing a written request for
arbitration with AAA. Subscriber, Republic and Harken agree that the Federal
Arbitration Act shall govern the disposition of all issues raised in the
arbitration proceeding. A decision in the arbitration proceeding shall be final
and binding on the parties.

11.
Notices. All notices or other communications required under this
Agreement shall be in writing and shall be deemed to have been duly given if
delivered personally or mailed by certified or registered mail, return receipt
requested, postage prepaid as follows: if to Subscriber, to the address set
forth on the signature page to this Agreement; and if to Republic or Harken to
their address as set forth in the Harken Disclosure Memorandum.

[The balance
of this page is blank]

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# SIGNATURES

By
signing this Agreement in the place indicated below, Subscriber represents to
Republic and Harken that: (a) Subscriber has read this entire Agreement, (b) the
information set forth below is accurate, (c) Subscriber agrees to exchange his
or her Debenture for Harken Common Stock as described in this Agreement, (d) the
person signing is empowered and duly authorized by the Debenture holder to
execute and carry out the terms of this Agreement and to exchange the Debentures
as described in this Agreement, and (e) this Agreement has been duly and validly
executed on behalf of the Debenture holder and constitutes a legal and binding
obligation of the Debenture holder.

# CORPORATION,
PARTNERSHIP, TRUST OR OTHER ENTITY

|_______________________________________
Name of Registered Owner of
Debenture ("Subscriber")
By_____________________________________
Signature
Its _____________________________________
Title
_______________________________________
Name Typed or Printed(       )
Fax Number
_______________________________________
Date |  | Address to Which Correspondence
Should be Directed
____________________________________
____________________________________
____________________________________
City, State, and Zip Code
____________________________________
Tax Identification or Social Security Number(       )
Telephone Number
$___________________________________
Principal Amount of Debenture
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |  | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

This
Debenture Exchange Subscription Agreement is accepted as of ___________, 2002
(the date of Closing of the Purchase and Sale Agreement dated January 31, 2002).

|REPUBLIC
RESOURCES, INC.
By __________________________________
     Patrick J. Duncan, President | HARKEN ENERGY CORPORATION
By_________________________________
     Bruce N. Huff, President
|------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------

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# SIGNATURES

By
signing this Agreement in the place indicated below, Subscriber represents to
Republic and Harken that Subscriber has read this entire Agreement, that the
information set forth below is accurate, and that Subscriber agrees to exchange
his or her Debenture for Harken Common Stock s described in this Agreement.

# INDIVIDUALS

|_______________________________________
Name of Registered Owner of
Debenture ("Subscriber")
_______________________________________
Signature
_______________________________________
Signature (Second Signature if Joint Owner)
_______________________________________
Name Typed or Printed(       )
Fax Number
_______________________________________
Date |  | Address to Which Correspondence
Should be Directed
____________________________________
____________________________________
____________________________________
City, State, and Zip Code
____________________________________
Social Security Number(       )
Telephone Number
$___________________________________
Principal Amount of Debenture
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

This
Debenture Exchange Subscription Agreement is accepted as of ___________, 2002
(the date of Closing of the Purchase and Sale Agreement dated January 31, 2002).

|REPUBLIC
RESOURCES, INC.
By __________________________________
     Patrick J. Duncan, President | HARKEN ENERGY CORPORATION
By_________________________________
     Bruce N. Huff, President
|------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------