Development of stable geological storage technology by using CO2 micro droplets

二氧化碳地质封存是大幅度减少大气中二氧化碳排放的最可行的方法之一。在含水层温压条件下，CO2进入超临界状态，浮力作用导致CO2向上运移。为了降低渗漏风险，本研究提出了向含水层内注入纳米级CO2液滴的方法。用表面活性剂制备了纳米级超临界CO2液滴，实验研究了液滴直径和分布随时间的变化规律。在高CO2浓度和低温条件下，观察到稳定的超临界CO2液滴。用X射线CT观察了注入到多孔介质中的超临界CO2液滴。然而，在毛细管力的作用下，在孔隙尺度上生长的二氧化碳液滴被稳定地捕获在每个孔隙中。

CO2 geological sequestration is one of the most feasible methods for substantial reduction of CO2 emissions into the atmosphere. Under conditions of temperature and pressure in aquifer, CO2 becomes supercritical state and upward migration of CO2 is caused by the buoyancy force. In order to reduce the leakage risk, injecting nano-scale CO2 droplets into the aquifer is proposed in this study. Nano-scale supercritical CO2 droplets were generated with surfactant and investigated their time evolution of its diameter and the distribution experimentally. At high CO2 density and low temperature condition, stable supercritical CO2 droplets were observed. Supercritical CO2 droplets that were injected into the porous media were observed by using X-ray CT. The CO2 droplets grew at pore-scale, however, were stably trapped in each pore by capillary force.