press release

Unocal begins its first oil production in Gulf of Thailand

El Segundo, Calif., Aug. 7, 2001 -- Unocal Corporation (NYSE: UCL) today said its Unocal Thailand, Ltd., subsidiary had started its first crude oil production in the Gulf of Thailand.

Early production from the Plamuk field is 2,500 to 3,000 barrels of oil per day (Unocal, 71.25% working interest) and is expected to increase to 15,000-18,000 barrels per day in the first quarter 2002.

"We expect to significantly increase production once we have completed installation of a new oil processing platform adjacent to existing gas processing facilities in the nearby Platong field," said Randy Howard, president of Unocal Thailand. "We are drilling additional wells in the Yala and Plamuk fields that will help us boost production ." The fields will produce a high-quality, light sweet crude oil. The production would increase Thailand's current indigenous oil output by about 25 percent.

Production from the Yala field will be added once the production area application is approved by the Thai government.

A new floating storage and offloading vessel, SIBEA, has been installed. In total, the company plans to produce from four new production platforms (2 in the Plamuk field and 2 in the Yala field), in addition to two existing platforms in the Kaphong field and one in the Surat field.

Unocal Thailand's co-concessionaires include Mitsui Oil Exploration Co., Ltd., and PTT Exploration and Production Public Company Limited.

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 operations are located in North America (Gulf of Mexico region, Alaska and Canada) and in Asia (Thailand, Myanmar, Indonesia, and Bangladesh). The company is also pursuing exploration programs in West Africa and Brazil.

Unocal Thailand has been producing natural gas in the Gulf of Thailand since 1981. Current gross gas production averages more than 1 billion cubic feet per day.

This news release contains certain forward-looking statements about Unocal's future production, permits, drilling plans, and capital investment. 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.

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: August 2001