Transgressive Talang Akar sands of the Kuang area, South Sumatra basin: origin, distribution and implication for exploration play concept

Abstract

Abstract Transgressive sands of the Talang Akar Formation are productive reservoirs in the South Sumatra Basin and have contributed more than 75 % of oil production in the basin. Sedimentation commenced by deposition of the Lower Talang Akar Formation at N6 characterized by coarse clastics, (an average porosity of 20 %, with permeability more than 5000 md) within a fluviodeltaic environment. The transgressive phase was continued by deposition of the Upper Talang Akar Formation at N7 which is typified by fine clastics, (porosity of 5 – 15 %, and permeability of 40 – 2400 md), deposited within a shallow marine environment. In the Kuang area, the distribution of productive Talang Akar reservoirs is generally controlled by basement highs, and stratigraphic traps form as onlaps along the flanks of the structural highs. The reservoir quality primarily depends on the rock types of local basement highs. Lower Talang Akar is productive in this area as shown by the BRG-005 well in the Beringin Field, which produces 1400 BOPD. The productivity of Upper Talang Akar in this area is demonstrated by the D-209 well of the Air Serdang Field which produces 3900 BOPD. The elements of a petroleum system consisting of source, reservoir, trap, seal and migration in the Kuang area are very favorable for hydrocarbon accumulations. The change of any elements of the petroleum system will lead to different exploration concepts. This paper discusses proven exploration play concepts involving Talang Akar Formation reservoirs in the Kuang area. Beringin Field is examined as it represents fluvial facies, and Air Serdang Field is examined as it involves shallow marine facies. The application of exploration play concepts of the Kuang area to other areas with similar petroleum systems will determine further exploration strategies in the South Sumatra Basin.