Gehem-1 is the first of a series of exploration wells that are designed to test the prospectivity of deeper, previously untested intervals underlying previous deepwater discoveries offshore East Kalimantan.
The Gehem-1 well encountered 617 feet (188 meters) of net gas and gas-condensate pay and 18 feet (5 meters) of net oil pay. The well was drilled in 5,981 feet (1,823 meters) of water to a total vertical depth of 15,241 feet (4,645 meters). More than 400 feet of the net pay was in a stratigraphic interval that had not been penetrated during drilling in the nearby Ranggas field.
The company said the Gehem structure covers nearly 8,000 acres (32.4 square kilometers) and has the potential for significant oil pay in several zones downdip of the Gehem-1 well and in deeper intervals, which will be tested in subsequent appraisal wells. Well designs for follow-up appraisals on the Gehem prospect will permit tests that are significantly deeper than the initial well, which encountered only moderate pressures even at total depth.
"Gehem-1 is potentially the most significant well we have drilled in the deepwater since the Seno discovery well in 1998 because it opens up a new, deeper oil and gas trend for us across our huge acreage holdings in the deepwater Kutei Basin," said Charles R. Williamson, Unocal chairman and chief executive officer. "Gehem-1 showed us that there is an extremely thick, high-quality hydrocarbon-bearing reservoir at previously untested depths."
Williamson added that the Gehem-1 results significantly increase the prospectivity of the deep oil prospects that are already on Unocal's drilling schedule for 2003 and dramatically expands the company's portfolio of leads and prospects focused on deeper oil and gas.
"Gehem by itself has a number of characteristics that favor early development," Williamson said. "The size of the potential Gehem resource, reservoir quality, potential high condensate yields and location relative to the Bontang liquefied natural gas plant, position Gehem to be a low-cost gas supplier to the plant."
The company said that Gehem has an unrisked resource potential of between 2 and 3 trillion cubic feet of gas equivalent. This does not include additional upside from still deeper horizons. The reservoir has the potential for flowing in excess of 100 million cubic feet of gas per day and 5,000 barrels of condensate per day per well.
The results of the Gehem-1 well indicate possibly significant oil and condensate resource potential in the deeper untested trend underlying the existing Gada, Gula, and Ranggas discoveries. In addition, armed with the information gathered from the Gehem-1 well, the company has already developed a number of new leads and prospects, including Golok (structure directly north of the Gula discovery), Geliga (structure south of the Gada discovery), and Rajalaut (adjacent to Ranggas).
The company also said that Unocal Rapak, Ltd., successfully completed drilling the Ranggas Selatan-1 appraisal well, extending the Ranggas field to the south on the Rapak production-sharing contract area. The Selatan-1 well was drilled to a true vertical depth of 10,243 feet (3,122 meters), and penetrated 187 feet (57 meters) of net oil pay and 258 feet (79 meters) of net gas pay in several zones of high quality reservoir rock. The well was not planned to penetrate the deep reservoir that was encountered in the Gehem-1 well.
The Selatan-1 well was drilled 1 mile (1.6 kilometers) south of the Ranggas-1 discovery well 5.7 miles (9.2 kilometers) north of the Gehem-1 well.
Unocal said it is conducting conceptual engineering studies for the possible development of the Ranggas field. "Extending the Ranggas oil and gas accumulations to the south is an important and positive appraisal step for the field," said Brian W. G. Marcotte, president of Unocal Indonesia Company.
"While we are still planning to have the Ranggas project ready for government approval by early next year, the Gehem-1 results have implications for appraising the deeper oil potential at Ranggas and optimizing the development."
Marcotte said the company plans to move Ranggas along while assessing the deep potential and options for co-development with Gehem.
Unocal Ganal is operator of the Ganal PSC area and holds an 80-percent working interest. Lasmo Ganal, Limited, a subsidiary of ENI (NYSE: E), holds the remaining 20-percent working interest.
Unocal Rapak is operator of the Rapak PSC area and holds and 80-percent working interest. Lasmo Rapak, Limited, a subsidiary of ENI, holds the remaining 20-percent working interest.
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