Is There Room for Gravity in Petroleum Exploration or is the Door Shut?

Abstract

A detailed gravity survey carried out by the Geological Survey of Western Australia (GSWA) used seismic grids over the Beharra Springs and Mondarra gas fields in the northern Perth Basin. In this part of the basin, seismic data are poorly imaged where the near-surface Tamala Limestone is present, whereas major structural elements are easily recognised using gravity data.The new gravity data reveal a major transfer zone and show distinctive signatures for the Dongara Terrace, Beharra Springs Terrace, and Allanooka High. Gravity lineaments within these structural units correlate with major faults interpreted from detailed seismic data. Additional features interpreted from gravity, but not identified on seismic sections, may lead to a revision of previous seismic interpretations. Furthermore, the majority of positive residual gravity anomalies correlate with seismically mapped structural highs that coincide with known hydrocarbon fields. Other positive gravity anomalies in the area may correspond to unidentified fields.