Publications

Faults are frequently a key element in a petroleum system, playing a significant role in defining the trap geometry and controlling the trapped hydrocarbon column height. Therefore, interpreted fault geometries should be validated by careful structural QC work to reduce risk and uncertainty. This is a particularly important consideration in the current study area, situated in an active tectonic margin of the Sunda Shelf. Major extensional faults trending NNE-SSW are mapped from seismic data. In addition, a NE-SW and NW-SE structural trend is also identified from the structural morphology of one of the deeper horizon surfaces. It is believed that this region has been subject to multiple tectonic episodes including collision of the Paternostermicroplate in the Cretaceous, extensional opening of the East Java Basin during Eocene followed by Middle to Late compression. Present-day stress magnitudes and orientations have been determined from bore-hole breakout, drilling induced fractures and LOTs from several wells. From this we calculate geomechanical stability (slip tendency) from which, we conclude that the NE-SW and NW-SE faults have been active in the most recent tectonic regime which is probably related to the Rembang-Madura-Kangean-Sakala Strike slip zone (RMKS). Using the same stress regime, the displacement discontinuity method shows that NESW faults most likely reactivated as left lateral strike slip faults and the NW-SE reactivated as right lateral strike slip faults. In the same model, with the same boundary conditions, the NNE-SSW faults reactivated as normal fault with small offsets. This is remarkably consistent with observations/ interpretation of faulted horizon offsets from the seismic data. The pattern of faults in the near surface, identified in the 3D seismic have the appearance of reidel shears. Our boundary element models demonstrate that these shears probably formed above a set of broadly orthogonal basement faults.