<PAGE>

                                                                    Exhibit 10.8

                            Titan Resources I, Inc.
                                   [Address]

                                    [Date]
[Executive Officer of Titan]


Dear ________:

     You ("Officer") and Titan Resources I, Inc. ("Resources") are parties to
that certain Officer Severance and Retention Bonus Agreement (the "Severance
Agreement") dated June 10, 1999, which provides you with certain compensation
and benefit arrangements upon a "Change of Control" (as defined in the Severance
Agreement) of Resources' parent, Titan Exploration, Inc. ("Titan").

     As you know, Titan has signed an Agreement and Plan of Merger (the "Merger
Agreement") dated December 13, 1999 with Union Oil Company of California, Titan
Resources Holdings, Inc. (the "Company") and TRH, Inc., pursuant to which Titan
will become a wholly-owned subsidiary of the Company.  The transactions
contemplated in the Merger Agreement (the "Merger") will constitute a "Change of
Control" under the Severance Agreement.  You are willing to enter into this
letter agreement in order to resolve any uncertainties and ensure that you
receive the Severance Payment (as defined below) at the closing of the Merger.

     In consideration the promises, covenants and obligations contained herein,
notwithstanding anything to the contrary in the Severance Agreement, Officer and
Resources agree as follows:

     1.   Severance Payment and Release.  On the closing date of the Merger, if
it occurs:

     (a)  Officer shall execute and deliver to Resources the General Release
("General Release") attached hereto as Exhibit A; and

     (b)  Resources shall pay to Officer $___________ (the "Severance Payment"),
which shall constitute the "Payment" as that term is used in the General
Release.  Notwithstanding the foregoing, in the event Officer has any
outstanding indebtedness (the "Indebtedness") to Resources or Titan on the
closing date of the Merger, the Severance Payment shall be paid as follows:

          (i)    to Officer, upon execution of the General Release, to pay any
                 federal income and excise taxes and any related payroll tax
                 obligations of Officer as a result of the Payment;

          (ii)   to Titan, to the extent necessary, to repay the Indebtedness;
                 and
<PAGE>

[Executive]
[Date]
Page 2

          (iii)  after the repayment of the Indebtedness referred to in clause
                 (ii) above, the remaining portion of the Severance Payment, if
                 any, will be paid to Officer.

     2.   No Consummation of Merger.  If the stockholders of Titan approve the
Merger Agreement and the Merger is consummated, a "Change of Control" under the
Severance Agreement will occur.  Officer agrees that in the event the Merger
does not occur, neither the execution of the Merger Agreement nor the approval
of the Merger Agreement by the Titan stockholders shall constitute a "Change of
Control" under the Severance Agreement or otherwise entitle the Officer to any
other benefit thereunder.

     3.   Entire Agreement/Severability.  This letter agreement and the
Severance Agreement constitute the entire agreement between the parties with
respect to the subject matter hereto and may not be modified or amended in any
way except as agreed in writing by both parties.  In the event that any of the
provisions contained in this letter agreement shall be determined to be invalid,
illegal or unenforceable in any respect, the remaining portions of this letter
agreement shall continue in full force and effect.

     4.   Binding Agreement; Assignment.  This letter agreement shall be binding
upon and inure to the benefit of the parties hereto and their respective
successors, heirs and permitted assigns. Neither this letter agreement nor any
of the rights, interests, or obligations hereunder shall be assigned by either
of the parties hereto without the prior written consent of the other party.

     5.   Third Party Rights.  Except for Titan, which the parties expressly
agree is a third party beneficiary with respect to this letter agreement,
nothing in this letter agreement, express or implied, is intended to or shall
confer upon any person other than the parties hereto, and their respective
successors and permitted assigns, any rights, benefits, or remedies of any
nature whatsoever under or by reason of this letter agreement.

     Please confirm your agreement with the foregoing by signing and returning
one copy of this letter agreement to the undersigned, whereupon this letter
agreement shall become a binding agreement between you and Resources.

                                    Very truly yours,

                                    TITAN RESOURCES I, INC.


                                    By:_____________________________________
<PAGE>

[Executive]
[Date]
Page 3

Accepted and agreed as of
the date first written above:


______________________________________
[Executive]
<PAGE>

                                                                       EXHIBIT A
                                                                       ---------

                           GENERAL RELEASE AGREEMENT
                           -------------------------

1.   GENERAL RELEASE OF CLAIMS UNDER AGE DISCRIMINATION IN EMPLOYMENT ACT. In
consideration of the Severance or Retention Bonus Payment ("Payment") to be made
to me under the Officer Severance and Retention Bonus Agreement (the
"Agreement"), I hereby release, acquit, and forever discharge (i) Titan
Resources I, Inc. and any parent, subsidiary, affiliated entity, successors or
assigns (the "Company"), and (ii) the stockholders, officers, directors,
employees, agents, representatives, and fiduciaries of the Company (collectively
the "Released Parties"), from any and all claims, liabilities, demands, and
causes of action of whatever kind or character, whether vicarious, derivative,
or direct, that I now have or claim against them arising under the Age
Discrimination in Employment Act.  This General Release does not waive rights or
claims that may arise after the date this General Release is executed. Further
in consideration of the Payment to be made to me under the Agreement, I
acknowledge and agree that the Released Parties may recover from me any loss,
including attorney's fees and costs of defending against any claim brought by
me, they may incur arising out of my breach of this General Release.

     I understand that I may revoke my acceptance of paragraph 1 of this
General Release by so notifying the Company within seven days of the date I
execute this General Release.  I further understand that if I do not timely
revoke my acceptance of paragraph 1, paragraph 1 of this General Release is
final and binding, and I agree not to challenge its enforceability.  If I do
challenge its enforceability, I agree initially to tender to the Company the
Payment made under the Agreement, and invite the Company to retain such money
and agree with me to cancel this General Release.  In the event the Company
accepts my offer, the Company shall retain such money and paragraph 1 of this
General Release will be void.  In the event the Company does not accept my
offer, the Company shall place such money in an escrow account pending the
resolution of any dispute as to whether paragraph 1 of this General Release
shall be set aside and/or otherwise rendered unenforceable.

2.   GENERAL RELEASE OF CLAIMS OTHER THAN UNDER AGE DISCRIMINATION IN EMPLOYMENT
ACT.  In consideration of the Payment to be made to me under the Agreement, I
hereby release, acquit, and forever discharge (i) the Company, and (ii) the
Released Parties, from any and all claims, liabilities, demands, and causes of
action of whatever kind or character, whether vicarious, derivative, or direct,
that I now have or claim against them connected in any way to the Agreement or
any claim for benefits under the Agreement (other than as described in Paragraph
3 below), or my employment, continuation of employment, or, if applicable,
termination of employment with any of the Released Parties, or with any other
act, conduct, or omission of any of the Released Parties, including but not
limited to claims arising under any federal, state, or local laws relating to
the employment relationship, other than claims, liabilities, demands, and causes
of action under the Age Discrimination in Employment Act.  This General Release
does not waive rights or claims that may arise after the date this General
Release is executed. Further in consideration of the Payment to be made to me
under the Agreement, I acknowledge and agree that the Released Parties may
recover from me any loss, including attorney's fees and costs of defending
against any claim brought by me, they may incur arising out of my breach of this
General Release.

3.   NO RELEASE OF COMPANY'S OBLIGATION TO MAKE TAX GROSS-UP PAYMENT UNDER THE
AGREEMENT.  Any provision of this General Release or the Letter Agreement
between
<PAGE>

the Company and myself dated of even date herewith to the contrary
notwithstanding, my execution of this General Release does not constitute a
release of the Company's obligation under the Agreement to make additional
payments to me if it shall be determined that I am subject to additional excise
tax under Section 4999 of the Internal Revenue Code of 1986, as amended, as a
result of any payments made or benefits provided to me pursuant to the Agreement
or otherwise in connection with a Change of Control (as defined in the
Agreement).

     I understand that I may not revoke my acceptance of paragraph 2 of this
General Release and that it is binding upon me whether or not I revoke my
acceptance of paragraph 1 of this General Release.

     I have read and fully understand all of the provisions of this General
Release.  I acknowledge that none of the Released Parties has made any promise
or representation to me in consideration for my agreement to execute this
General Release that is not set out in this General Release, and that in
executing this General Release I am not relying on any such promise or
representation but instead am relying solely on my own judgment.  I further
acknowledge that my execution of this General Release is knowing and voluntary,
that I have had a reasonable time to consider its terms, and that I have been
advised to consult with an attorney about this General Release.


Date signed:________________________     _______________________________________
                                         Signature of Employee

Date signed:________________________     _______________________________________
                                         Witness