Estimation of CO₂ storage capacity in fractured porous reservoirs requires a better understanding of the CO₂-water flow fundamentals in fracture-matrix systems. There are few core-flood experiments on three-dimensional CO₂-water drainage in a fracture-matrix system, yet none have examined the impacts of the capillary continuity of fractures and fracture-matrix interactions. In this study, twelve drainage experiments were conducted in four fracture-matrix columns, each comprising a vertical stack of a cylindrical rock core, a filter paper serving as an analogue to a horizontal fracture, and a ceramic plate. The core sample was surrounded by open space at the top and circumferential sides to model fractures, allowing for 3-D CO₂-water drainage in the rock core and displaced water draining across the horizontal fracture. X-ray computed tomography was conducted to visualize the dynamic invasion/drainage processes in four rock core samples showing contrasts in anisotropy, permeability, and heterogeneity. Experimental results show (1) the equilibrium CO₂ saturations in the rock matrix vary from 0.10 to 0.60 at controlled capillary pressures up to 200 kPa, (2) the CO₂ saturations in the matrix increaze with water saturation in the horizontal fracture resulting in better capillary continuity for water to drain across the fracture, and (3) the fracture water saturation can be enhanced by the non-uniform fracture capillary pressure and countercurrent flow of CO₂ and water across the fracture-matrix interface. In the case of high fracture water saturation, matrix CO₂ saturation largely depends on matrix anisotropy and heterogeneity. The core-scale experimental results contribute to understand the fracture-matrix interactions and CO₂ storage efficiency in fractured porous media.

裂缝多孔储层中CO ₂存储容量的估计需要更好地理解裂缝-基质系统中的CO ₂ -水流基本原理。关于裂缝-基质系统中三维CO ₂ - 排水的岩心-驱油实验很少，但没有人研究过裂缝的毛细管连续性和裂缝-基质相互作用的影响。在这项研究中，在四个裂缝基质柱中进行了 12 次排水实验，每个柱体包括垂直堆叠的圆柱形岩芯、用作模拟水平裂缝的滤纸和陶瓷板。岩心样品在顶部和圆周侧被开放空间包围，以模拟裂缝，允许 3-D CO ₂- 岩心排水和横断水平裂缝排水。进行 X 射线计算机断层扫描以可视化四个岩心样本中的动态侵入/排水过程，显示各向异性、渗透率和非均质性的对比。实验结果表明（1）在控制毛细管压力高达 200 kPa 的情况下，岩石基质中的平衡 CO ₂饱和度从 0.10 到 0.60 不等，（2）基质中的 CO ₂饱和度随着水平裂缝中的水饱和度而增加，从而导致更好的(3) 不均匀的裂缝毛细管压力和CO ₂逆流可以提高裂缝水饱和度和水穿过裂缝-基质界面。在裂缝含水饱和度高的情况下，基质CO ₂饱和度很大程度上取决于基质的各向异性和非均质性。岩心规模的实验结果有助于了解裂缝多孔介质中的裂缝-基质相互作用和 CO ₂储存效率。