press release

Unocal optimistic after successful Trident deepwater appraisal well

Sugar Land, Texas, Jan. 24, 2002 - Unocal Corporation (NYSE: UCL) today said that it continues to be encouraged after successfully completing the first appraisal well at the Trident deepwater Gulf of Mexico discovery in Alaminos Canyon Block 903. The well, located approximately one and a-half miles northwest of the original discovery, was drilled to a total depth of 20,500 feet in 9,727 feet of water.

"The combination of lateral continuity and quality of reservoir rock encountered in this well is a cause for optimism," said Mike Bell, vice president of Unocal's Deepwater USA business unit. "This is an important step forward on the path to establishing commerciality. However, significant work lies ahead before we have a commercial development plan that gives us the confidence to move forward."

The objectives of the appraisal well were to test the downdip extent of the productive intervals found in the Trident discovery well and to gather critical information about reservoir quality. The appraisal well encountered the same hydrocarbon-bearing intervals found in the discovery well, a favorable indication of lateral reservoir continuity. The well penetrated oil-water transition zones.

In one of the key findings, preliminary analysis of the core data confirms the presence of good quality reservoir rock in the key uppermost pay zones in the structure. Tests conducted on oil samples taken from the appraisal well indicate the same fluid quality of 40 API gravity found in the discovery well, which is an important factor in future development economics.

The company said it may drill a second appraisal well at Trident as early as the second half of 2002 and plans to put significant effort into analyzing deepwater development options, including the likely use of FPSO technology.

The appraisal well was drilled in 68 days at a gross cost of $32 million. Unocal is operator and has a 59.5-percent working interest in the prospect. Co-venturers include Chevron U.S.A. Production Company (NYSE: CVX), 15%; Ocean Energy, Inc. (NYSE: OEI), 12.75%; Agip Petroleum Co., the American subsidiary of Eni SpA (NYSE: E), 8.5%; and Phillips Petroleum Company (NYSE: P), 4.25%.

About Unocal Corporation

Unocal is one of the world's leading independent natural gas and crude oil exploration and production companies. The company's principal oil and gas operations are located in North America (Gulf of Mexico region, Permian Basin, Alaska and Canada) and in Asia (Thailand, Myanmar, Indonesia, Bangladesh and Azerbaijan). The company is also pursuing exploration programs in Brazil and West Africa. 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 plans and the results of geological analysis. 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 2000 Form 10-K and subsequent reports filed with the Securities and Exchange Commission.

Cautionary Note to U.S. Investors: The U.S. Securities and Exchange Commission permits oil and gas companies, in their filings with the SEC, to disclose only proved reserves that a company has demonstrated by actual production or conclusive formation tests to be economically and legally producible under existing economic and operating conditions. Unocal uses certain terms in this news release, such as "resource potential," that the SEC's guidelines strictly prohibit Unocal from including its filings with the SEC. U.S. investors are urged to consider closely the disclosure in Unocal's 2000 Form 10-K (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: January 2002