EXHIBIT (a)(4)
 
                                     LOGO
                                  May 3, 1998
 
The Board of Directors
Union Texas Petroleum Holdings, Inc.
1330 Post Oak Boulevard
Houston, Texas 77056
 
Members of the Board:
 
  Atlantic Richfield Company, a Delaware corporation ("Parent"), VWK
Acquisition Corp., a Delaware corporation ("Sub"), and Union Texas Petroleum
Holdings, Inc., a Delaware corporation (the "Company"), propose to enter into
an agreement and plan of merger (the "Merger Agreement"), which provides for,
among other things, the tender offer (the "Offer") by Sub for all of the
issued and outstanding shares of common stock, par value $.05 per share (the
"Shares"), of the Company at $29.00 per Share, net to the seller in cash, and
the merger (the "Merger") of Sub with and into the Company, as a result of
which the Company will become a wholly owned subsidiary of Parent. Upon
consummation of the Merger, each Share (other than Shares owned by the
Company, Sub, Parent or any wholly-owned subsidiary of the Company, Sub or
Parent) will be converted into the right to receive $29.00 in cash.
 
  You have requested our opinion as to whether the per Share consideration to
be received by the holders of the Shares in the Offer and the Merger is fair
from a financial point of view to such holders.
 
  In arriving at our opinion, we have, among other things:
 
  1.reviewed certain publicly available business and financial information
          relating to the Company, including (a) the Annual Reports on Form
          10-K and related audited financial statements for the fiscal years
          ended December 31, 1996 and December 31, 1997 and (b) the Quarterly
          Report on Form 10-Q and related unaudited financial statements for
          the fiscal quarter ended March 31, 1998;
 
  2.reviewed estimates of the Company's oil and gas reserves prepared by (a)
          DeGolyer & MacNaughton ("D&M") as of January 1, 1997 and January 1,
          1998 and (b) the management and staff of the Company as of December
          31, 1996, December 31, 1997 and March 31, 1998;
 
  3.analyzed certain historical and projected financial and operating data of
          the Company prepared by the management and staff of the Company;
 
  4.discussed the current and projected operations and prospects of the
          Company with the management and staff of the Company;
 
  5.reviewed the historical trading history of the Shares;
 
  6.compared recent stock market capitalization indicators for the Company
          with the recent stock market capitalization indicators for certain
          other publicly traded independent energy companies;
 
  7.compared the financial terms of the Offer and the Merger with the
          financial terms of certain other transactions that we deemed to be
          relevant;

 
  8.reviewed drafts dated May 2, 1998 of the Merger Agreement and the related
         stockholder agreement;
 
  9.reviewed such other financial studies and analyses and performed such other
         investigations and took into account such other matters as we have
         deemed necessary or appropriate.
 
  In preparing our opinion, we have assumed and relied upon, without assuming
any responsibility for verification, the accuracy and completeness of any
information supplied or otherwise made available to us by the Company. We have
further relied upon the assurances of the management of the Company that it is
unaware of any facts that would make the information provided to us incomplete
or misleading in any material respect. With respect to projected financial and
operating data, we have assumed that they have been reasonably prepared on
bases reflecting the best currently available estimates and judgment of the
management of the Company relating to the future financial and operational
performance of the Company. With respect to the estimates of oil and gas
reserves, we have assumed that they have been reasonably prepared on bases
reflecting the best available estimates and judgments of the management of the
Company and D&M relating to the oil and gas properties of the Company. We have
not made an independent evaluation or appraisal of the assets or liabilities of
the Company or, except for the estimates of oil and gas reserves referred to
above, been furnished with such an evaluation or appraisal.
 
  Our opinion relates solely to the fairness from a financial point of view of
the per Share consideration to be received by the holders of Shares in the
Offer and the Merger. This opinion is for the use and benefit of the Board of
Directors of the Company and does not constitute a recommendation to any holder
of Shares as to whether such holder should tender any Shares pursuant to the
Offer or how such holder should vote on the Merger. We have not been asked to
consider, and this opinion does not address, the after-tax consequences of the
Offer or the Merger to any particular holder of Shares. As you are aware, we
have acted as financial advisor to the Company and we will receive a fee from
the Company, a substantial portion of which is contingent upon the consummation
of the Merger, and we will receive a fee for rendering this opinion.
 
  Our opinion is rendered on the basis of conditions in the securities markets
and the oil and gas markets prevailing as of the date hereof and the condition
and prospects, financial and otherwise, of the Company as they have been
represented to us as of the date hereof or as they were reflected in the
materials and discussions described above.
 
  Based upon and subject to the foregoing, it is our opinion that, as of the
date hereof, the per Share consideration to be received by the holders of
Shares in the Offer and the Merger is fair from a financial point of view to
such holders.
 
                                        Very truly yours,
 
                                        /s/ Petrie Parkman & Co., Inc.
                                        PETRIE PARKMAN & CO., INC.