Is there any room for gravity in petroleum exploration?

Abstract

A detailed gravity survey has been carried out by the Geological Survey of Western Australia over seismic grids covering the Beharra Springs and Mondarra gas fields in the northern Perth Basin. In this part of the northern Perth Basin, where the near surface Tamala Limestone is present, seismic data is poorly imaged whereas major structural elements are easily recognised using gravity data. The new gravity data reveal a major transfer zone and three distinctive zones with specific signatures, coincident with the Dongara Terrace, Beharra Springs Terrace, and Allanooka High. The gravity lineaments within these tectonic units correlate strongly 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 interpretation. Furthermore, positive residual gravity anomalies correlate well with seismically mapped structural highs that coincide with known hydrocarbon fields. Other positive gravity anomalies may correspond to yet unidentified fields. Thus, gravity data provide a cost-effective tool in the search for hydrocarbons in areas with little or poor quality seismic data.