press release

Unocal drills fifth successful well on deepwater Ranggas field in Indonesia

El Segundo, Calif., May 10, 2002 -- Unocal Corporation (NYSE: UCL) today said that its Unocal Rapak, Ltd., subsidiary has drilled the fifth successful well on the deepwater Ranggas oil field offshore Indonesia.

The Ranggas-5 well encountered 203 feet (62 meters) of net oil pay and 618 feet (188 meters) of net gas pay. The well was drilled in 5,412 feet (1,650 meters) of water to a total vertical depth of 11,858 feet (3,614 meters). The well is located 1.5 miles (2.4 kilometers) north of the Ranggas-1 discovery well and 0.7 mile (1.1 kilometers) south of the Ranggas-4 well, which was recently tested at 8,158 barrels of oil and 6.4 million cubic feet of gas per day from a single interval.

"We are excited by the results of the Ranggas-5 well because the well penetrated more net pay than any other well in Unocal Indonesia's long history", said Brian Marcotte, president of Unocal Indonesia Company. "Because of our successful appraisal drilling program, we have initiated engineering and development studies for the field."

Unocal Rapak is operator of the Rapak production-sharing contract area. It holds an 80-percent working interest, while Lasmo Rapak, Limited, a subsidiary of ENI S.p.A., holds the remaining 20-percent working interest.

About Unocal Corporation

Unocal is one of the world's leading independent natural gas and crude oil exploration and production companies. The company's oil and gas activities are in North America, Asia, Latin America, the North Sea, 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 development plans. 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 Annual Report on Form 10-K and subsequent reports filed with the Securities and Exchange Commission.

U.S. investors are urged to consider closely the disclosure in Unocal's 2001 Annual Report on 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.

Under the terms of the PSCs, Unocal Indonesia Company and its affiliates, including Unocal Rapak, Ltd., as contractors to Pertamina, the Indonesia national oil company, are entitled to varying shares of the oil and gas produced from commercial discoveries.

Updated: May 2002