Surface geological investigation as the initial stage of hydrocarbon exploration in Kei Besar Island, Southern Maluku

Abstract

Kei Islands are known to have hydrocarbon potentials in shallow rock layers, trapped by folds and faults. This potential is characterized by the amount of gas seepage found in Kei Kecil, Kei Besar and Tayandu Island. The study was conducted in central and southern part of Kei Besar Island through outcrop observations and stratigraphic measurements aim to recognize the physical characteristics of rock. Kei Besar Island located in the easternmost part of Australian continental passive margin separated by the extension of Aru Through. Digital Elevation Model of Kei Besar Island shows that the northern part of research area has a steeper morphology than the southern. The stratigraphic characteristic in the central part of research area dominated by clastic limestone showing a shallowing-up stacking pattern. While in the southern part, the lithology dominated by coralline limestone contains many fragments of coral and large foraminifera. Stratigraphic analysis shows that lithology in the study area was formed in carbonate submarine fan which formed Elat Formation. This formation underlained by shallow carbonate rock which contain large foraminifera from Tamangil Formation. Tamangil Formation interfingered with lower part of Weduar Formation. Based on the analysis of surface data above, concluded that subsurface exploration is necessary to reconstruct the petroleum system in research area.