press release

Unocal resumes drilling of second appraisal well on deepwater Trident prospect

Sugar Land, Texas, Oct. 7, 2002 - Unocal Corporation (NYSE: UCL) today said that the Discoverer Spirit drillship has resumed drilling of the second appraisal well at the Trident deepwater Gulf of Mexico discovery in the Gulf of Mexico after a 15-day delay caused by storms Isidore and Lili.

The Discoverer Spirit had spudded the well on Sept. 17. The company expects the well to take 45 to 60 days to drill. The new well is located on Alaminos Canyon block 947, approximately two miles southwest of the original discovery well on block 903, which was announced in July 2001. The first appraisal well was completed on block 903 in January 2002.

The Trident prospect area covers seven blocks in Alaminos Canyon. Unocal is operator and has a 59.5-percent working interest in the prospect. Co-venturers include Chevron U.S.A. Inc. (NYSE: CVX), 15%; Ocean Energy, Inc. (NYSE: OEI), 12.75%; Agip Petroleum Co., the American subsidiary of Eni SpA (NYSE: E), 8.5%; and ConocoPhillips (NYSE: COP), 4.25%.

About Unocal

Unocal Corporation is one of the world's leading independent natural gas and crude oil exploration and production companies. Unocal's principal oil and gas activities are in North America, Asia, Latin America, and the North Sea. Unocal is one of the world's largest producers of geothermal energy with operations in the Philippines and Indonesia.

This news release contains certain forward-looking statements about Unocal's future drilling performance. These statements are not guarantees of future performance. 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 as a result of factors discussed in Unocal's 2001 Form 10-K/A and subsequent reports filed with the Securities and Exchange Commission.

U.S. investors are urged to consider closely the disclosure in Unocal's 2001 Form 10-K/A (SEC File No. 1-8483). Copies of the company's SEC filings are available from the company by calling 800-252-2233. The reports are also available on the Unocal web site. You can also obtain this form from the SEC by calling 800-SEC-0330.

Updated: October 2002