On the Effect of CO2 on Seismic and Ultrasonic Properties: A Novel Shale Experiment

Carbon capture and storage (CCS) by geological sequestration comprises a permeable formation (reservoir) for CO2 topped an impermeable (caprock). Time-lapse (4D) seismic is used to map movement in the subsurface: migration into caprock might change its properties thus impact integrity. Simultaneous forced-oscillation pulse-transmission measurements are combined quantify Young’s modulus Poisson’s ratio as well P- S-wave velocity changes absence presence of at constant ultrasonic frequencies. This combination laboratory proxy 4D because rock monitored over time. It also improves understanding frequency-dependent (dispersive) needed comparing in-situ measurements. To verify our method, Draupne Shale during three consecutive fluid exposure phases. shale appears be resilient integrity neither compromised notable nor changes. No significant dispersion observed. attributed being calcite-poor acidic CO2-bearing brine that may suitable candidate CCS.