Investigation of CO2 microbubble assisted carbon sequestration and gravity-induced microbubble ripening in low permeability reservoirs

In carbon geo-sequestration, CO2 were injected into the reservoir, separating considerable amount of carbon emissions form the atmosphere. Conformance control is one of the key factors affecting carbon sequestration efficiency because high mobility contrast and reservoir heterogeneity would reduce sweep efficiency, leading to poor sequestration efficiency. In this work, the conformance control of non-chemical microbubble in low permeability reservoir was experimental investigated and acquired data was employed for reservoir simulation. Then, reservoir simulations were performed to investigated the sequestration performance of CO2 microbubble. The effect of conformance control, reservoir heterogeneity, gas-liquid ratio and reservoir dip angle were comprehensively analyzed. The results indicated that microbubble can achieve higher total sequestration amount than CO2 gas injection due to superior conformance control, especially in heterogenous reservoir and reservoir with dip angle. Finally, the numerical simulation was performed to predict the ripening of capillary trapped microbubble at geological time scale after injection. To establish the relationship between reservoir simulation and microbubbles ripening simulation, the function between reservoir permeability and simulation parameters is first time introduced. The simulation results demonstrate that microbubbles can maximize capillary trapping, effectively delaying the formation of a gas cap, and reducing the risk of leakage in low permeability reservoirs. In general, simulation results demonstrate that CO2 microbubble is a superior carbon sequestration technology with higher efficiency and safety. This study provides valuable insights and guidelines for field applications of non-chemical CO2 microbubble assisted carbon geo-sequestration.