STRUCTURAL STYLES AND PETROLEUM SYSTEM MODELLING OF THE NORTH MAKASSAR STRAITS, INDONESIA

摘要

The northern Makassar Straits lies within the offshore portion of the Kutai Basin, a very prolific petroleum province of Central Indonesia. Within this Basin, GDF SUEZ EPI has interests in Muara Bakau and North Ganal exploration licenses and is looking at opportunities to expand its portfolio in Indonesia. As part of a regional review of the northern Makassar Basin, an integrated study was undertaken to detail the tectonic evolution and remaining hydrocarbon potential of the area. The study uses the interpretation of speculative 2D seismic lines, 2D basin modelling and well data. The results of our study demonstrate that the northern Makassar Basin initiated with a rifting of Middle Eocene to Early Oligocene age. This resulted in the development of a number of basement faults oriented NNW-SSE and organized in an en-echelon pattern. At the same time, a proto- delta of the Mahakam River seems to have developed southwards of its present-day location. Northwest/southeast trending compression started in Middle Miocene and continued until the present day. Basin inversion and uplift were generated, together with faults reactivation and development of broad anticlines within the basement. Fault inversion was prominent in the relay ramps and accommodation zones occurred in between the en- echelon basement faults. Thick-skinned tectonics were coupled with a thin- skinned deformation initiated within the overlying sediments of the Mahakam Delta progradation system. This led to the development of extensional growth faults near the shelf break and toe-thrusts associated with tight and asymmetric folds. Progressive compression, while delta progradation continued, produced reactivation of the extensional growth faults and further uplift of the anticlines. The results of our structural study were then used as input for 2D basin modeling which allowed us to improve our understanding of the regional petroleum system and assess potential opportunities within this area.