press release

Unocal-led venture tests deepwater Indonesia well at combined 19,344 b/d rate from three intervals

El Segundo, Calif., Feb. 10, 1999 - Unocal Corporation today said that its latest deepwater appraisal well in the West Seno field offshore East Kalimantan, Indonesia, flowed at a combined daily rate of 19,344 barrels of oil and 18.6 million cubic feet of gas from three intervals.

The West Seno #4 appraisal well was drilled in 3,101 feet (945 meters) of water. It encountered 398 feet (121 meters) of vertical oil and gas pay between 6,690 feet (2,040 meters) and 9,010 feet (2,746 meters) true vertical depth subsea (TVDS). The combined flow rate include tests of three intervals totaling 142 feet (43 meters) of the pay. The details of the three drill stem tests are provided in the table below.

"These test results confirm that our main pay intervals are capable of high production rates and document the excellent potential of the thin-bedded pay sections in the Seno reservoir," said Timothy C. Lauer, president and managing director of Unocal Indonesia Company. "The West Seno #4 tests further confirm our confidence that we have a significant hydrocarbon resource in the Seno area."

The West Seno field is the first deepwater oil and gas field offshore East Kalimantan that Unocal Makassar, Ltd., and its co-venturer, Mobil Makassar, Inc., plan to develop and one of several prospective areas on the greater Seno structure in the Kutei Basin. Unocal had earlier estimated gross recoverable oil and gas resources for the West Seno field alone at 150 million barrels-of-oil-equivalent.

Unocal has said it plans to fast-track the development of the West Seno field, with oil production anticipated to start in 2001. An additional appraisal well is planned in the West Seno field before spudding the first exploration well on the highly prospective Central Seno prospect immediately to the east of the West Seno field.

West Seno is located in the Makassar Strait production-sharing contract area. Unocal Makassar is operator and has a 50-percent working interest. Mobil Makassar holds the remaining 50% interest.

West Seno 4 DST Results

Interval Tested
(TVDS)
Choke Flowing Tubing
Pressure
Flow Rate/
API gravity
DST #1 8,621'-8,666' 1-3/4" 717 psi 8,250 b/d oil
43° API
8.8 mmcf/d gas
DST #2 7,576'-7,621' 1/2" 1,182 psi 2,373 b/d oil
42° API
2.5 mmcf/d gas
DST #3 7,415-7,467' 1-3/4" 711 psi 8,721 b/d oil
43° API
7.3 mmcf/d gas

Forward looking statements about recoverable resources, resource potential and future exploration and development activities in this news release are based on assumptions concerning geological, market, competitive, regulatory, environmental, operational and other considerations. Actual results could differ materially.

Under the terms of the PSC, Unocal Makassar, as a contractor to Pertamina, the Indonesian national oil company, is entitled to varying shares of the oil and gas produced from commercial discoveries.

Updated: February 1999