Seismic sequence stratigraphy and facies characterisation of the G and H units within the Goodwyn Field Northern Carnarvon Basin Western Australia
Iasky, Vickie C.
Honours Degree, 2004
University of Adelaide
The distribution and geometry of the reservoir sands (H and G units) of the Lower Triassic Mungaroo Formation in the Goodwyn Gas Field, Dampier Sub-basin, Northern Carnarvon Basin, was interpreted from 3D seismic data. The data consisted of a 3D seismic volume extracted from the 3D Demeter Seismic Survey, which covered most of the Goodwyn Gas Field. The wavelet for the data set was rotated 90 degrees and amplitudes were extracted from proportionally sliced layers within five H unconformably- bounded sequences within the H unit (H1-H5) and within one unconformably – bounded sequence within the G unit.
Both manual facies maps and amplitude-extracted facies maps were created to map the study area, although the amplitude-extracted facies maps provided more insight into the depositional systems, geometries and timing of events, as they are not as subjective.
The major fault trends in the field influence the fluvial axes, northeast-southwest (H2, H5 and unit G) and northwest-southeast (H1, H3 and H4). The Goodwyn faults also influenced the accommodation space throughout the G and H unit and influenced the connectivity of the sands.
The sequence stratigraphic model of the H unit consists of six sequences blocky at the base, overlain by progressively more isolated sand fluvial channel belts. The overlying sands of the G unit have greater connectivity than those of the H sequences and appear to be laterally and vertically amalgamated sand channel belts. Seismic amplitude data indicate that the H unit consists of splays, floodplains, high and low sinuosity channels within discrete or laterally amalgamated channel belts, and the G unit of avulsing high sinuosity channels forming channel belt complexes. These channels can provide potential stratigraphic traps at multiple levels within the Goodwyn Field.