Publications

The South Lho Sukon 'A' field, approximately 35 kilometers southeast of the giant Arun Gas Field in North Sumatra, was discovered in July 1972 by the SLS-A1 well, which was drilIed on a reef buildup over a basement high. Six appraisal wells, three of which tested commercial quantities of gas, have been drilled since 1974.About 2,600 kilometers of conventional 2-D seismic data have been collected and interpreted since 1969, and a 3-D seismic survey was completed in 1987 for reservoir delineation and field development. The seismic interpretation indicates that the field lies between the southeasternly trending Arun High and the Alur Siwah High.The Lower Miocene Peutu reef which rests on pre- Tertiary metamorphic basement is overlain by a regressive sequence of Neogene marine clastic rocks ranging from Middle Miocene Baong shales to Plio- Pleistocene Julu Rayeu sandstones and conglomerates. These overlying rocks were mildly folded and faulted during the Barisan Orogeny in Plio-Pleistocene time.The South Lho Sukon gas was trapped in reefal limestones consisting of boundstones, grainstones and wackestones. As at Arun, the reservoir limestones were deposited in reef, near-reef and ",lagoonal", environments in Early to Middle Miocene time.The field is approximately 2,000 acres in size, and has 30 to 800 feet of net pay. Average porosity is 8 to 15% and average water saturation is 14 to 29%. The reservoir pressure is about 4,120 psi at 8,700 feet subsea and the formation temperature is 350°F.A detailed study of reservoir porosity trend combining with 3-D mapping of reservoir thickness above the gas/ water contact resulted in an upward revision of the reserves. The field is planned to be on stream by 1993.