Filed by Unocal Corporation
                           Pursuant to Rule 425 under the Securities Act of 1933
                                           Subject Company: Pure Resources, Inc.
                                                   Commission File No. 001-15899

                                                         Dated: October 23, 2002



                                             UNOCAL
                                             2141 Rosecrans Avenue, Suite 4000
                                             El Segundo, California 90245


                       [GRAPHIC OMITTED][GRAPHIC OMITTED]

                                             NEWS RELEASE

                                             Contact:  Barry Lane (Media)
                                                       310-726-7731
                                                       Robert Wright (Investors)
                                                       310-726-7665

Unocal Announces Extension of Offer for Pure Resources

EL SEGUNDO, Calif., Oct. 23 -- Unocal Corporation (NYSE: UCL) today said that,
in light additional disclosure made today by Pure Resources, Inc. (NYSE:
PRS), it was extending, effective immediately, the offer by its Union Oil
Company of  California  subsidiary to exchange 0.74 shares of Unocal common
stock for each share of common stock of Pure not currently owned by Unocal.  The
offer has been extended  until 12:00  midnight,  New York City time, on Tuesday,
Oct. 29, 2002.

The offer remains subject to the conditions included in the offer as amended
through Oct. 18, 2002, including the condition that a sufficient number of
Pure shares are tendered to result in Union Oil owning at least 90 percent of
Pure's outstanding common stock.

Unocal said that 5,554,231 Pure shares had been tendered and not withdrawn as
of the close of business on Oct. 22, 2002.  When combined with the Pure
shares already owned by Union Oil, this represents approximately 76 percent
of Pure's outstanding common stock.

ADDITIONAL INFORMATION
A prospectus, which is part of Unocal's amended Registration Statement on Form
S-4, and related exchange offer materials, including a letter of transmittal,
has been mailed to stockholders of Pure. Investors and stockholders of Pure are
urged to read all of these documents carefully as well as the additional
material filed by Pure today. These documents contain important information
about the transaction and should be read in connection with making a decision
with respect to the exchange offer.

Unocal has filed its  Registration  Statement on Form S-4 and a Schedule TO
with the Securities and Exchange  Commission  (SEC).  Investors and stockholders
are able to obtain  free copies of these  documents  through the SEC's web site,
WWW.SEC.GOV.  For additional  information on the exchange offer or copies of any
of the offering  materials,  stockholders  may contact D.F. King & Co., Inc., at
800-769-6414.  In addition, Merrill Lynch is the dealer-manager for the exchange
offer and may be contacted at 866-276-1462.





In addition to the amended Registration Statement on Form S-4, Schedule TO,
prospectus and related exchange offer materials, both Unocal and Pure file
annual, quarterly and special reports, proxy statements and other information
with the SEC. You may read and copy any reports, or other information filed by
Unocal or Pure at the SEC public reference room at 450 Fifth Street, NW,
Washington, D.C. 20549, or at any of the SEC's other public reference rooms in
New York City, N.Y., and Chicago, Ill. Please call the SEC at 800-SEC-0330 for
further information on the public reference rooms. The SEC filings by Unocal and
Pure are also available to the public from commercial document- retrieval
services and at the SEC web site.

ABOUT UNOCAL CORPORATION
Unocal is one of the world's largest independent natural gas and crude oil
exploration and production companies. Based in El Segundo, Calif., Unocal's
principal production operations are in North America, Asia, and the North Sea.
Unocal is also one of the world's largest producers of geothermal energy with
operations in Indonesia and the Philippines. More information about the company
is available at WWW.UNOCAL.COM.

ABOUT PURE RESOURCES, INC.
Pure is an independent exploration and production company that develops and
produces oil and natural gas in the Permian Basin, the San Juan Basin, the Gulf
Coast and the Gulf of Mexico. The company also owns an undivided interest under
approximately 6 million gross fee mineral acres throughout the Southern Gulf
Coast region of the U.S. Pure was formed in May 2000 through the combination of
Titan Exploration, Inc., and the Permian Basin business unit of Unocal
Corporation.

                                     *****
This news release contains certain forward-looking statements about future
business transactions involving Unocal and Pure. These statements are not
guarantees of future performance and involve certain risks and uncertainties
that are difficult to predict. The statements are based upon Unocal's current
expectations and beliefs and are subject to a number of known and unknown risks
and uncertainties that could cause actual results to differ materially from
those described in the forward looking statements. Actual results could differ
materially from what is expressed or forecasted in this news release. Those risk
factors are discussed in the Unocal and Pure Annual Reports on Form 10-K, in
each case as amended, and subsequent reports that have been filed by the
companies with the U.S. Securities and Exchange Commission.
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