R&D on Stable CO2 storage by means of capillary trapping

二氧化碳（CO_2）被注入地质构造以减缓气候变化。首先，CO_2驱替盐水，使其充满多孔岩石的孔隙空间。这一过程受到毛细作用、浮力和粘性剪切应力的强烈影响。其次，卤水再次置换CO_2，但由于毛细作用，一部分CO_2将被截留在多孔岩石中。然后捕获的CO_2气泡将溶解到盐水中。在油藏规模下，由于含CO_2的饱和卤水和非饱和卤水的密度差异，自然对流限制了CO_2向卤水中的溶解。我们实验研究了这些过程中的孔隙尺度通过X射线计算机断层扫描。为了预测注入CO_2的长期归宿，为每个过程开发了新的数学模型。

Carbon dioxide (CO_2) is injected into geological formations to mitigate climate change. First, CO_2 displaces brine which fills pore space of porous rock. This process is strongly influenced by capillarity, buoyancy and viscous shear stress. Next, brine displaces CO_2 again, but some fraction of CO_2 would be trapped in porous rock because of capillarity. Then trapped CO_2 bubbles would be solved into the brine. In a reservoir scale, dissolution of CO_2 into the brine is limited by the natural convection due to the density differences between unsaturated and saturated brine with CO_2. We experimentally investigated these processes in a pore scale by means of X-ray computer tomography. To predict long-term fate of the injected CO_2, novel mathematical models were developed for each process.