Sequence stratigraphic responses to shoreline-perpendicular growth faulting in shallow marine reservoirs of the Champion field, offshore Brunei Darussalam, South China Sea: Reply

Abstract

The Champion field, offshore Brunei Darussalam, comprises a thick middle-upper Miocene succession of shallow marine sediments associated with major growth fault systems and deposited as part of the paleo-Baram delta. The structural evolution of the Champion field has resulted in an unusual situation where growth faults strike perpendicular to the paleoshoreline orientation. Shoreface parasequences and tidal-estuarine complexes are mapped directly from three-dimensional (3-D) seismic data calibrated from wells. The seismic interpretations provide chronostratigraphic correlations that are more robust than some well-based markers because the seismic interpretations have better spatial coverage. Depositional responses to growth faulting are defined by two end-member models, (1) layer thickening and (2) addition of layers in the hanging wall. Layer addition makes correlation across faults problematical. Growth may be accommodated by either or a combination of these processes, and areas of layer addition are related to transgressive events in the hanging wall. Topographic changes thought to be associated with fault movements may fundamentally change shoreline type, sand body orientations, and petrophysical properties for discrete periods of time. These stratigraphic complexities are linked spatiotemporally to accommodation history but cannot be adequately predicted from well data alone.