Abstract: Structural Evolution of the Pematang Reservoirs, Kelabu-Jingga Gas Fields, Sumatra
J. E. Laing, S. P. Atmodipurwo, Ahmiyul Rauf
The Kelabu-Jingga area, located in the Kiri Trough of the central Sumatra Basin, produces gas from the Paleogene Pematang Group. The Pematang Group consists of sandstones, claystones, organic-rich shales, and conglomerates deposited in fluvial and fresh-water deltaic and lacustrine environments. Deposition occurred during a regional extensional tectonic event that resulted from a major plate reorganization in the Pacific and Indian oceans 43 m.y. Subsequent rifting and basin development occurred in the Kiri Trough area in central Sumatra. Deposition of the Pematang Group during active extension resulted in lateral discontinuity of individual sand members. Syngenetic listric faults and associated "rollover" formed during rifting.
During the Neogene, oblique convergence resulted in a regional transpressional event, which overprinted the earlier extensional style of faulting. In the Kiri Trough area, both extensional and transpressional features are evident. A Jingga Kelabu 3-D seismic survey combined with wireline logs (including dipmeter and FMS data) and core provides geological information useful for identifying both faults and depositional trends within the Pematang Group. The resultant maps and cross sections show hydrocarbon reserves and new drilling opportunities in the Kelabu-Jingga fields.
AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994