Relationships Among Ultrasonic Velocities and Attenuations of Carbonate Reservoir Rocks

Ultrasonic P- and S-wave velocity (Vp, Vs) and attenuation (Qp-1, Qs-1), including azimuthal variations in Vs (wave propagation parallel to bedding), were measured on 12 core samples from a Russian carbonate reservoir at 40 MPa effective pressure using the laboratory pulse echo-system. While relationships between velocities, attenuations and porosity and permeability do not reveal any significant features, cross-plots of the ratios Vp/Vs and Qp-1/Qs-1 allow some categorisation of these carbonate rocks in terms of porosity and permeability ranges. In particular, low porosity (< 5%), low permeability (< 0.1 mD) carbonate rocks plot in a separate group to intermediate porosity and permeability carbonate rocks. The results show the value of combined velocity and attenuation datasets to reservoir characterisation.