Experimental Study of Microbubble CO2 Flooding in Heterogeneous Sedimentary Rock

To investigate the effect of microbubble CO2 flooding for CO2 geological sequestration and utilization, we designed a laboratory experiment that visualizes the CO2 movements in rock specimens by using X-ray computed tomography (CT). We carried out this experiment together with porosity calculation, fluid saturation monitoring and mass flow measurements for ejected fluids. A specially designed porous filter was used for the microbubble CO2 generation. Sarukawa sandstone (Japan) with heterogeneous structures was used in this study. This specimen is the same as the specimen used in the experiment which was carried out by the conventional method. We compare the two results here. The microbubble CO2 flooding experiment was carried out until the CO2 injection reaches about 1 PV (pore volume). When it reached 1.0 PV in both experiments, the total fluid recoveries, which was checked by four times fluid recoveries, were 23.96% and 17.29% in the microbubble case and the conventional method case, respectively. In both cases, almost all of the CO2 passed preferentially to the top of the specimen for reasons of sample heterogeneity. However, the microbubble case showed higher CO2 saturation and fluid recoveries. This represents that microbubble CO2 injection is more effective than conventional CO2 injection for CO2 geological sequestration and utilization.