press release

Unocal tests Ranggas oil discovery on deepwater Rapak PSC offshore Indonesia

El Segundo, Calif., April 8, 2002 -- Unocal Corporation (NYSE: UCL) today said that its Unocal Rapak, Ltd., subsidiary successfully tested an appraisal well in the deepwater Ranggas oil field offshore Indonesia.

The Ranggas-4 appraisal well flowed at a daily rate of 8,158 barrels of oil and 6.4 million cubic feet of gas from a single interval between 10,174 feet (3,101 meters) and 10,224 feet (3,116 meters) true vertical depth subsea (TVD). The drillstem test had flowing tubing pressure of 1,223 pounds per square inch on a 56/64-inch choke.

The test rates were constrained by test equipment, but initial daily production rates from a well producing from this single zone are estimated at upwards of 10,000 barrels of oil and 8 million cubic feet of gas.

The Ranggas-4 well encountered 181 feet (55 meters) of net oil pay and 57 feet (17 meters) of net gas pay. The well was drilled in 5,208 feet (1,587 meters) of water to 11,252 feet (3,430 meters) TVD. The well is located 2.4 miles (3.8 kilometers) north of the Ranggas-1 discovery well and 1.2 miles (1.9 kilometers) south of the Ranggas-3 appraisal well.

"The oil test rates are impressive, and we are very encouraged at this point in our appraisal program", said Brian Marcotte, president of Unocal Indonesia Company. "The test results are another step towards commercializing our third deepwater oil field in Indonesia."

Marcotte said the company plans to spud the Ranggas-5 appraisal well, also on the main Ranggas structure, before the end of April.

With the results of the Ranggas-4 well, Unocal currently estimates the gross discovery volume for the main Ranggas structure is about 200 to 350 million equivalent barrels of oil, with additional potential in other prospects on the same trend. Earlier, Unocal had estimated the unrisked exploration potential of the entire Ranggas complex at 350 to 650 million equivalent barrels of oil. Unocal has now drilled six wells in the Ranggas complex, and all have discovered hydrocarbon potential.

Additional drilling

Two wells were drilled recently to test structures on both the north and the west parts of the large central Ranggas prospect.

The Ranggas Utara-1 well encountered 33 feet (10 meters) of net oil pay and 44 feet (13 meters) of net gas pay. The well was drilled in 5,258 feet (1,603 meters) of water to 12,650 feet (3,856 meters) TVD. The well is located 2.5 miles (4.0 kilometers) north of the Ranggas-3 well. This accumulation was deemed sub-commercial as an independent development at this time, but demonstrates the potential for additional hydrocarbons to the north of the Ranggas field.

The Ranggas West-1well encountered 85 feet (26 meters) of net gas pay in two intervals. The well was drilled to 9,955 feet (3,034 meters) TVD in 4,483 feet (1,366 meters) of water. The well is located 2.9 miles (4.6 km) west of Ranggas-3. This accumulation could most likely be tied back to the future Ranggas development facilities via a single subsea well. Oil potential remains in the southern extension of this trend.

Marcotte added that several additional prospects on trend or adjacent to the main Ranggas structure remain to be drilled. This includes the Api prospect where the Api-1 well is currently being drilled.

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, 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 drilling plans, possible development activities, discovery volume and estimated production rates. Discovery volume is a speculative estimate of ultimate recovery (including non-proved resource) based on engineering, geophysical, and geological studies and may include market risk. 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.

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 "discovery volumes," 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 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: April 2002