Rock physics interpretation of heterogeneous and anisotropic turbidite reservoirs

In this paper, we create rock physics templates for heterogeneous and anisotropic thin-bedded sand-shale intervals as a function of group angle, net-to-gross, saturation and porosity as variable parameters. These templates are basically cross-plots of acoustic impedance versus P- to S-velocity ratio. We apply these templates to interpret well log data from a vertical and a deviated well, respectively, in a North Sea turbidite system. We are able to infer the shale anisotropic elastic moduli and Thomsen parameters by comparing the measured velocities in a deviated well with the velocities in an adjacent vertical well. Our modeling captures the observed trends in the data as we go from a vertical well to a deviated well through a heterogeneous reservoir saturated with light oil and water. We can clearly see how the reservoir properties changes due to the presence of anisotropy. We also perform an AVO sensitivity study as a function of heterogeneity and hydrocarbon saturation.