The numerical modelling of sandstone pinch-outs and drapes in the Bowen Basin, Queensland

Abstract

Although the Bowen Basin is considered to provide good quality seismic exploration records, the limits of seismic resolution are tested when attempting to interpret sandstone pinch-outs and drapes. Exploration is hindered by seismic resolution constraints in both the vertical and lateral directions. Exploration in the Bowen Basin frequently concentrates on the Rewan Formation and Showgrounds Sandstone, one objective being to determine if a sandstone pinch-out, drape or fault has disrupted hydrocarbon migration paths. This paper stresses that to assist the determination of whether a potential target is a drape over, or a pinch-out against a basement high, it is desirable to initially build a geophysical model to simulate the geological boundaries. After running a suite of simulated seismic surveys over a number of models, results indicate that the top of the Showgrounds Sandstone could be interpreted where its thickness was greater than 10 metres. It was also apparent that a 10 metre drape over the top of the basement high could not be detected with reflection data of frequency content less than 70 Hz.