The effect of stress on the acoustic properties of carbonate rocks

Bart Verberne & Conxita Taberner - Shell

Authors – Bart Verberne, Luuk Kleipool, Conxita Taberner, Arjan van der Linden, Fons Marcelis, Sander Hol and Axel Makurat
Understanding acoustic velocity variations in rocks is important for operation of hydrocarbon, geothermal, and CO2-storage reservoirs. Using a triaxial loading apparatus to simulate realistic subsurface stress conditions, we measured ultrasonic wave velocities of core plug samples composed of i) near-pure calcite limestone (bulk grain density ρg ≈2.70 gcm-3), characterized by widely varying pore types, and ii) dolostone-dominated samples which are compositionally varying (ρg = [2.66-2.80] gcm-3) but which are texturally relatively uniform. Comparison of wave velocity properties at selected key stress states revealed important differences between reservoir stress conditions versus near-isostatic conditions, and between limestone samples with different pore types.