Master of Science (Hons.)
Department of Geology
Amier, Rubianto Indrayudha, Coals, source rocks and hydrocarbons in the South Palembang sub-basin, south Sumatra, Indonesia, Master of Science (Hons.) thesis, Department of Geology, University of Wollongong, 1991. http://ro.uow.edu.au/theses/2828
The South Palembang Sub-basin, in the southern part of the South Sumatra Basin, is an important area for coal and oil production. In order to develop the economy of this region, an understanding of the coal and source rock potential of the Tertiary sequences within the South Palembang Sub-basin is essential.
Collisions between the Indo-Australian and the Eurasian Plates formed the South Sumatra Basin and particularly influenced the development of the South Palembang Sub-basin since the Middle Mesozoic to Plio-Pleistocene.
The Tertiary sequences comprise from oldest to youngest unit; the Lahat, Talang Akar, Baturaja, Gumai, Air Benakat, Muara Enim and Kasai Formations. These sequences were developed on the pre-Tertiary rocks which consist of a complex of Mesozoic igneous rocks and of Palaeozoic and Mesozoic metamorphics and carbonates.
Coals occur in the Muara Enim, Talang Akar and Lahat Formations. The main workable coal measures are concentrated in the Muara Enim Formation. The Muara Enim coals are brown coal to sub-bituminous coal in rank, while the Lahat and Talang Akar coals are sub-bituminous to high volatile bituminous coals in rank. From the viewpoint of economically mineable coal reserves, the M2 Subdivision is locally the most important coal unit. Thicknesses of the M2 coals range from 2 to 20 metres. The coals can be utilized for electric power generation, gasification but are generally unsuitable as blends for coke manufacture. They have some potential for the manufacture of activated carbons.
In general, coals and DOM of the Tertiary sequences are dominated by vitrinite with detrovitrinite and telovitrinite as the main macerals. Liptinite is the second most abundant maceral group of the coals and DOM and comprises mainly liptodetrinite, sporinite and cutinite.
The Lahat, Talang Akar, Air Benakat and Muara Enim Formations have good to very good hydrocarbon generation potential. The Baturaja and Gumai Formations have less significant source potential as this unit contains little organic matter but in some places these formations are considered to have good potential to generate gas.
The vitrinite reflectance data and studies using the Lopatin model indicate that the onset of oil generation in the South Palembang Sub-basin occurs below 1500 metres. In general the Gumai Formation lies within the onset of oil generation zone, but in some places, the lower part of Air Benakat and Muara Enim Formations occur within this zone.
Crude oil geochemistry shows that the oils are characterized ' by high ratios of pristane to phytane indicating a source from land-derived organic matter. The presence of bicadinane-type resin and oleanane in the oils is further evidence of a terrestrial source. The biomarker and thermal maturity of the source rocks and coals from the Talang Akar Formation are similar to those of the oils studied.