3D geological model for King Sound, Canning offshore basin, Western Australia using FALCON high resolution airborne gravity gradiometry

Abstract

A 3D geological model for King Sound, in the offshore Canning Basin, Western Australia, was produced by interpretation of FALCON® high resolution airborne gravity gradiometry and magnetic data, aided by 2D gravity models, 2D seismic data and well logs. Pseudo-depth slices of the vertical gravity gradient (GDD) and magnetic data and interpreted seismic horizons were used to constrain the vertical distribution of sedimentary sequences, intrasedimentary intrusives and basement rocks. Basement depth was determined from the magnetic data using traditional profile-based automated magnetic depth estimation techniques with well control. The 3D model indicates an elevated, fault-bounded platform of Archaean to Proterozoic basement in the north. The platform is rimmed by Late Devonian and Early Carboniferous carbonate reefs and carbonate breccias and in the south, contemporaneous siliciclastic submarine fans and turbidite deposits occur in a deep marine environment. Density values derived from published literature and measured in wells at King Sound were assigned to units in the geological model. A forward model was calculated and compared to the observed GDD data. The assigned density values were then modified, within the expected range for each rock type, using property inversions until a good fit between the modelled and observed data was obtained. Models derived from potential field data can be beneficial for petroleum exploration in frontier basins worldwide, where only limited well and seismic data are available. The 3D geological model provides a good framework for use in designing future exploration programs in the area and it aids data visualisation and interpretation.