Statistical rock physics analysis and modelling in the Browse Basin

Summary In this study, we performed rock physics analysis and modelling in the Browse Basin, in which we analysed the relationships among elastic properties of end-member (EM) sandstone (SST) and EM-shale, and then, modelled the properties of non-EM-SST and non-EM-shale to simulate seismic amplitude responses at boundaries of realistic litho-facies. We found that the elastic properties of SST of the basin has similar trends to those in other basins; therefore, we adopted existing rock physics relationships with minor adjustments. On the other hand, it was found that the careful consideration of mineralogy and overpressure is required in the EM-shale trend analysis. The observed data was well defined by a semi-empirical rock physics model including the effect of the volume of clay (Vcl) variation and by an “Equivalent depth method” which accounts for overpressure. To express the elastic behaviour in mixed sand-clay systems, we adopted a “Triangular diagram model” and the established trends of defined EM facies. Simulated properties from this approach agree well with actual data from the Browse Basin.