press release

Unocal Thailand completes appraisal drilling of Pakarang gas field

Bangkok, June 28, 1999 -- Unocal Thailand, Ltd., today said four new delineation wells have further confirmed the commerciality of the Pakarang gas field in the Gulf of Thailand.

Pakarang is located in Concession Block 11, north of the Erawan field. It is under a gas sales contract with the Petroleum Authority of Thailand.

The Pakarang-6 well reached a depth of 11,348 feet and encountered 174 feet of gas-bearing sands. Pakarang-7 was drilled to 11,821 feet and found 347 feet of gas-bearing sands. Pakarang-8, drilled to 11,881 feet, found 165 feet of gas-bearing sands. And Pakarang-9 encountered 161 feet of gas-bearing sands after reaching 12,871 feet.

All wells were of the slimhole design. No flow tests were conducted, but gas samples collected indicated good gas quality. These latest four wells completed the Pakarang appraisal program.

Last year, the company confirmed the commerciality of the Pakarang field. With the latest drilling, Unocal now estimates the gross gas resource potential for Pakarang between 275 and 550 billion cubic feet. The company is currently reviewing the new data to determine a plan and schedule for field development. Although gas was first discovered in 1983, it was only in 1998 that Pakarang-4 and -5 extended the known boundaries of the original field.

"Data from these Pakarang wells further confirm the economic potential of the field," said Randy Howard, regional vice president and president of Unocal Thailand. "As Thailand turns more and more to clean-burning natural gas for industrial users and power generation by EGAT, Unocal has the reserves to meet that growth in natural gas demand."

Co-concessionaires in the Pakarang field are Mitsui Oil Exploration Co., Ltd. (23.75%), and PTT Exploration and Production Public Company Limited (5%). Unocal Thailand, as the operator, holds the remaining 71.25% working interest.

Unocal Thailand is a subsidiary of Unocal Corporation, one of the world's largest independent oil and gas exploration and production companies, with resource development, power plant and pipeline projects in Asia, the US Gulf of Mexico region, and Latin America. Unocal Thailand currently operates 11 natural gas and condensate fields in the Gulf of Thailand, with gross daily production of about one billion cubic feet and 33,000 barrels of condensate a day. Unocal supplies about two-thirds of the natural gas used by Thailand.

Forward-looking statements regarding future operations and resource potential in this news release are based on assumptions concerning market, competitive, regulatory, environmental, operational and other considerations. Actual results could differ materially as a result of factors discussed in Unocal's 1998 Form 10-K report filed with the U.S. Securities and Exchange Commission.

Updated: June 1999