Monitoring CO2 drainage and imbibition in a heterogeneous sandstone using both seismic velocity and electrical resistivity measurements

作者：Kim Jongwook; Nam Myung Jin^*; Matsuoka Toshifumi

来源：Exploration Geophysics, 2016, 47(1): 24-31.

DOI：10.1071/EG15002

• carbon dioxide (CO2)
• CO2 drainage
• CO2 imbibition
• monitoring
• P-wave velocity
• resistivity
• Tako sandstone

In a laboratory fluid-injection experiment, seismic velocity and electrical resistivity were measured simultaneously to monitor injected carbon dioxide (CO2) during CO2 drainage and imbibition within a heterogeneous, clay-containing Tako sandstone sample. In the CO2 drainage process, supercritical CO2 (10 MPa at 40 degrees C) was injected under a condition similar to that of an in situ reservoir. After the CO2 drainage process, water was injected into the CO2-injected sandstone for the CO2 imbibition stage. Employing strategies based on Gassmann fluid-substitution and Archie's equation, P-wave velocities and electrical resistivities were interpreted to evaluate CO2 saturation (S-CO2). Estimated values of S-CO2 during the CO2 drainage process were compared with those of volume-derived S-CO2, which were obtained by evaluating the volumes of injected and drained fluid. When Tako sandstone S-CO2 is < 0.1, S-CO2 estimation from P-wave velocity based on the Gassmann-Brie equation (with e = 12) is more precise than resistivity index (RI)-based Archie's equation estimations from electrical resistivity. For further analysis, a modified RI equation was also employed to estimate S-CO2, and the results were compared with those of the original RI-based Archie strategy.

• 出版日期2016-3