Comprehensive petro‐elastic modeling aimed at quantitative seismic reservoir characterization and monitoring

Abstract

We simulate a poorly consolidated shaly sandstone reservoir model representing a prograding near‐shore zone geological pattern. To account for the spatial distribution of petrophysical properties, an effective porosity model is first simulated by Gaussian geostatistics. Dispersed clay and dual water models are then efficiently combined with other well‐known theoretical and experimental petrophysical correlations to consistently simulate reservoir model parameters. Next, the constructed reservoir model is subjected to numerical simulation of multi‐phase fluid flow to predict the spatial distributions of fluid pressure and saturation. Finally, a geologically consistent stress‐sensitive rock physics model, followed with the modified Gassmann theory for shaly sandstones, is utilized to simulate inverted seismic elastic parameters. As a result, the comprehensive petro‐elastic model developed in this paper can be efficiently utilized in sensitivity analyses of seismic elastic parameters to petrophysical properties and, ultimately, applied to seismic reservoir characterization and monitoring research. As an example, we choose to present a sensitivity analysis of inverted seismic attributes and their crossplotting as a tool to discriminate the effect of pressure and saturation in a time‐lapse seismic study. Sensitivity analysis demonstrates that [AI vs. SI] is the most effective and stable crossplot to quantitatively separate saturation and pressure changes. It is also shown that saturation patterns are much easier to detect compared to that of pressure.