Thermal history of the south Palembang sub-basin, South Sumatra, Indonesia.

摘要

The South Sumatra basin is a back-arc basin with complex tectonic and thermal history. The study area was selected to determine the relationship between structural development and thermal history, and to establish the petroleum system.; Changes in global tectonics affect structural and thermal history of the study area. Abrupt slowing of the convergence rate in early Tertiary created the back-arc basin. Increasing convergence rates between Indo-Australian oceanic plate and Sunda microplate since the middle Miocene formed basin inversion with a strike-slip dominant, and increased heat flow over the past five million years. The increasing heatflow within shorter period is suggested by Apatite Fission Track Annealing and vitrinite reflectance data.; Fluid inclusion, seismic, and stratigraphic data imply the distinct features for later uplifting followed by erosion. Both vitrinite reflectance data and apatite fission track data suggest the presence of recycled material within the upper strata. Depth-porosity curves and pressure data suggest under-compacted shale associated with sealing capability of the tuffaceous clay within the Gumai Formation.; Strongly terrestrial influenced source rock is present in the Limau, but marine-related source rock is present in the Muara Enim area. Effective source rocks currently at Limau graben are the shale and coal of the Talang Akar and Lahat Formations, while in the Muara Enim area an effective source rock is the Gumai shale. At least two source rock types exist in the study area: kerogen type III, and kerogen type II. Mixed kerogens are common within the Talang Akar and Lahat shale. Oleanane-rich, medium gravity, and low sulfur are typical of crude oils in the study area. No supporting data for lacustrine-related oil or source rock are present.; Vertical fractures may enhance migration efficiency and the migration pathway from an effective source rock to reservoir.; The results of this study provide new insights for the exploration concept in the south Sumatra Basin.