Publications

A comprehensive geosciences synthesis has been carried out of the petroleum system of the Kangean area and integrated into a 3D numerical basin model capable of simulating dynamically sediment deformation coupled with heat, water and hydrocarbon transfers. The objective of the modeling was to constrain the long-debated origin of the various accumulations known in the area, with a special attention given to the oils of the Sepanjang Field. The 3D basin model covers the Northern Platform, Central High and Southern Basin tectonic provinces, over an area of 250 km E-W and 150 km N-S. The dynamic simulations are controlled by calibrated sub-models of heat flow distribution, overpressure occurrence, and Late Neogene erosion. Dynamic simulations suggest that the charging of the Sepanjang Field originates from the late Neogene depocenter that formed in the West-Central part of the Southern Basin as a result of the uplift and erosion of the Central High. The depocenter activates eastward the oil expulsion ring of the Ngimbang source rock, mostly already entirely overmature to the West. Oil migration occurs northeastward updip to the newly formed Sepanjang structure, and remains contained within the Ngimbang reservoir complex, thanks to the thick overpressured overburden and the absence of direct vertical conduits. This charging model, combined with the atypical signature of the Sepanjang oils, implies that mixed terrestrial-marine organic facies of the Ngimbang source rock are present West of the Southern Basin, with several implications for exploration in the area. The Sepanjang oil accumulation appears to be the result of a complex interplay of thermal, hydrodynamic and geological processes that can only be understood and predicted using advanced dynamic simulations methods. Recent drilling activities in the deep-water domain of the Southern Basin have validated the forecast capabilities of the 3D basin model.