THE HV11 3-D SEISMIC SURVEY: SKUA – SWIFT AREA GEOLOGY REVEALED?

Abstract

The 4630 km of HV11 3-D seismic survey data, shot over the Skua and Swift fault blocks in Timor Sea licence AC/L4, reveals details of Tithonian faulting not evident previously. The HV11 survey provided 10 times the data density of previous coverage and significantly improved data quality through the recording of lower frequencies and use of accurate navigation systems and high resolution processing parameters.

Tithonian faulting is revealed as a series of northeast-trending en echelon faults overprinting a deeper, north-northeastern, possibly latest Triassic, trend which defines the major fault block boundaries. Transfer of fault throw between en echelon segments appears to be by strike ramps with no evidence for cross-cutting transfer faults. Skua Field fault geometries preclude Upper Jurassic, right lateral strike-slip tectonics. Semi-regional fault trends also have an en echelon style with transfer of fault throw by strike ramps. Escarpments developed along the Tithonian faults are also evident on the HV11 data.

The direction of Tithonian extension is interpreted to be oblique to the deeper fault trend, giving rise to the en echelon Tithonian fault style. Each en echelon segment appears to control an hydrocarbon accumulation, which may be due to fault-independent drape over palaeotopographic relief.

En echelon Miocene faulting, incisement and depositional mounding in the Puffin Formation are also detailed by the HV11 seismic data. The HV11 survey demonstrates the value of acquisition of 3-D seismic data as an exploration tool in an area of complex and subtle structural geology.