Toward an Integrated and Realistic Interpretation of Continuous 4D Seismic Data for a CO₂ EOR and Sequestration Project

In 2015, Saudi Aramco commenced its first carbon capture and sequestration project, with carbon dioxide (CO2) injected into a small area of a carbonate reservoir located in the Eastern Province of Saudi Arabia. To monitor the expansion of the CO2 plume, continuous 4D seismic data is being recorded at an average rate of one survey per month. The interpretability of data requires: (1) a high degree of repeatability, which has been achieved through dedicated acquisition and processing, (2) sufficient sensitivity of seismic data to injected CO2, (3) accurate characterization of reservoir heterogeneity, and (4) a fit-for-purpose workflow to interpret time-lapse seismic images. This paper focuses on the last three points. First, a rock physics model (RPM) is calibrated from available well data (well logs, fluid analysis), showing that CO2 injection causes a drop in both acoustic impedance and Poisson's ratio of 6% at the well log scale, leading to moderate seismic data sensitivity, an...