Seismic screening for hydrocarbon prospects using rock-physics attributes

Abstract Rock-physics templates (RPT), in combination with seismic AVO inversion data, can be used to screen for hydrocarbon prospects during exploration. With the improved quality and increased use of elastic seismic inversion, there has recently been a paradigm change in prospect mapping in the oil industry, and quantitative interpretation has become a widely used jargon. Rock-physics models are essential in that they help in converting elastic parameters from inversion data to reservoir parameters. In the screening phase of inversion data, rock-physics models also can reveal hydrocarbon-associated anomalies. Two new rock-physics attributes help in detecting hydrocarbons from seismic—the curved pseudo-elastic impedance and the trend angle. The first of these is similar to the extended elastic impedance or the fluid factor in that it represents a deviation from a wet-background trend in a rock-physics template. However, it honors the nonlinear nature of a compaction trend. The trend angle is a measure of slope angle between two adjacent data points in the AI-versus-VP/VS crossplot, and this attribute will highlight fluid trends in the data. Those two attributes can be used complementarily to detect and highlight hydrocarbon accumulations, as demonstrated on data from the Norwegian shelf.