Abstract - The Champion field, offshore Brunei Darussalam, Borneo, comprises a thick Middle-Upper Miocene succession of wave-dominated shoreface and tidal/estuarine sediments deposited as part of the palaeo-Baram delta. A high resolution 3D Acoustic Impedance (AI) seismic dataset in conjuction with a database of over 100 wells has been used to aid correlation of shoreface sand bodies across growth faults within the area.
The reservoir sequence is developed in the hangingwall of a large (throw > 500ms), westward-dipping growth fault. Three phases of footwall collapse, caused by ‘backstepping’ of the bounding fault into the footwall block, were responsible for the observed migration of both the axis of the hangingwall rollover and associated zone (0.5 – 1 km wide) of eastward-dipping growth faults towards the footwall during extension. As a result, the reservoir is highly compartmentalised and comprises several narrow, NE-SW trending blocks bounded by mainly eastward-dipping faults. Detailed structural mapping, using horizon continuity maps and fault-slicing techniques, shows that growth of these antithetic faults was dominated by segment interaction and linkage, following near-instantaneous fault propagation. Relay ramps, which occur on apparently continuous faults with a broad range of displacements, maintain continuity between footwall and hangingwall and therefore impact directly on both fault seal capacities and on present-day production flow. The effect of relays ramps will be particularly important in compartmentalised reservoirs such as those in the Champion field.
Abstract of talk given to:
3D Seismic, Burlington House, London, November 2001