press release

Unocal records two new deepwater discoveries in Indonesia

El Segundo, Calif., Nov. 9, 1999 Unocal Corporation today said that oil and gas has been discovered in the Bangka and Aton prospects in the Rapak Production Sharing Contract (PSC) area. These discoveries further confirm that the company's Kutei Basin deepwater properties offshore Indonesia have significant hydrocarbon resource potential.

The Bangka discovery is located 9 miles (14 km) north of the West Seno field. The Bangka #2 well was drilled to a depth of 9,752 feet (2,972 m) in 3,191 feet (972 m) of water and encountered 367 net feet (112 m) of liquid-rich gas pay in the Upper Miocene. The Bangka #2 pay is confined to two zones of high-quality reservoir rock with hydrocarbon columns calculated to be greater than 500 feet (152 m). The follow-up Bangka #4 well was drilled downstructure in 3,234 feet (986 m) of water to a depth of 11,656 feet (3,553 m) and encountered significant thickness reservoir sands, including 38 feet (12 m) of net oil and gas pay. The Bangka #5 well, located 3.5 miles (5.6 km) northwest of the Bangka #2 well, is currently being drilled.

The Aton discovery is located 5 miles (8 km) southeast of the Bangka #2 well. The Aton #3 well was drilled to a depth of 8,465 feet (2,580 m) in 3,826 feet (1,166 m) of water and encountered 255 feet (77 m) of high quality reservoir and 80 feet (24 m) of oil and gas pay. A follow-up well, the Aton #1, was drilled to a depth of 12,465 feet (3,800 m) in 3,644 feet (1,111 m) of water and encountered significant reservoir sands and 59 feet (18 m) of net oil and gas pay in two zones.

"The Bangka and Aton discoveries are the result of the integration of the data from earlier wells and attest to the evolving understanding of the deepwater exploration play," said Brian W. G. Marcotte, president and general manager of Unocal Indonesia Company. "We think we have found an important key for exploring in the Upper Miocene, and we are much more confident in our ability to predict the occurrence of significant sand accumulation in the area."

Marcotte noted that an additional 300 square miles (800 sq km) of new 3D seismic data will be available before the end of the year.

Unocal has now made 5 deepwater Upper-Miocene oil and gas discoveries offshore Indonesia since beginning its exploration program in 1998. Two of the discoveries, Merah Besar and West Seno, have received approval from Pertamina for Plans of Development.

The commercial potential of the other three discoveries -- Janaka North, Bangka and Aton -- is under evaluation, with further drilling planned for all three discoveries.

Unocal has drilled 12 deepwater wells in the Kutei Basin since June. Those 12 wells were drilled for an average cost of $4.6 million, with an average drilling time of 14.2 days.

Details of the individual well results are shown in the attached table.

The Nakula #1 well was the first Unocal well drilled in water more than one-mile deep. Earlier, the company said that it was capable of extending the limits of the Sedco 601 semisubmersible drilling rig to water depths of up to 6,000 feet.

Looking forward, Unocal plans to proceed with its Indonesia deepwater exploration program on two fronts.

In addition to the current well on the Bangka prospect, additional wells are planned for the Janaka North and Nakula prospects before the end of the year. In January, two to four Middle Miocene tests will be drilled on large anticlines in the Ganal PSC, south of the Makassar productive trend.

Unocal, through various subsidiaries, is operator of the East Kalimantan, Ganal, Sesulu, Rapak and Makassar Strait PSC areas. The company holds working interests of 100 percent in East Kalimantan, 80 percent in Ganal and Sesulu (Lasmo 20%), 60 percent in Rapak (Mobil 30%; Lasmo 10%) and 50 percent in Makassar Strait (Mobil 50%).

Forward-looking statements regarding future exploration activities 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 Corporation's 1998 Form 10-K report filed with the U.S. Securities and Exchange Commission.

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

Unocal East Kalimantan Deepwater Drilling Update

1999 Activity (May -- November)

Well Name (PSC) Rig Days Water Depth (feet) Well Depth (feet) Pay (feet) Remarks
Gep #1 (Ganal)* 13 4143' 13,065' 38' Gas pay
Giram #1 (Ganal)* 11 4330' 12,065' 0 Dry hole
Gambah #1 (Ganal)* 20 4350' 14,565' 30' Gas pay and oil shows
Aton #2 (Rapak)* 20 4281' 13,215' 0 Dry hole
Pari #1 (Rapak) 17 4477' 15,350' 21' Oil pay
Janaka N. #4 (Rapak) 16 4241' 13,400' 14' Oil pay
Nilai Utara #1 (Rapak) 18 4663' 16,000' 0 Dry hole
Bangka #2 (Rapak) 12 3191' 9,752' 367' Gas discovery
Aton #3 (Rapak) 8 3826' 8,456' 80' Oil and gas discovery
Nakula #1 (Rapak) 12 5312' ** ** **
Bangka #4 (Rapak) 8 3234' 11,656' 38' Oil and gas pay
Aton #1 (Rapak) 9 3644' 12,465' 59' Oil and gas pay
Total - last 12 wells 170 $55.8 million
Average - last 12 wells 14.2 4141' 12,951' $4.6 million ($359/ft)
Average YTD - 22 wells 13.6 3834' 12,757' $4.7 million ($374/ft)

Updated: November 1999