Abstract In this study, two supercritical CO2 (scCO2) injection experiments (microbubble flow injection (MBI) and conventional flow injection (CI)) were performed using the same Berea sandstone sample to investigate the unique transport characteristics of microbubble flow. The four-dimensional characteristics of spatial CO2 saturation ( S CO 2 ) and the relationship to the spatial porosity were investigated by utilizing the X-ray computed tomography (CT) imaging. The results show that the microbubble flow has a stronger sweep efficiency than that of the conventional flow, ultimately resulting in higher S CO 2 . According to the statistics of saturation distribution, MBI can improve the pore space utilization, particularly in the medium-sized porosity space. Several CO2 preferential flows, migrated along with the high-permeability layers, were identified. Comparing to CI, the accumulation of CO2 in pore space was enhanced in many local macro-regions during MBI, which produced a discrete distribution manner. These flows not only improve the displacement efficiency of CO2 in occupied pore space but also further enhance the subsequent vertical CO2 infiltration from the high-to low-permeability layers. The final experimental result shows that the dual advantages of CO2 microbubble flow in sweeping and displacement can effectively improve CO2 storage capacity.

中文翻译：

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基于体素的X射线计算机断层扫描成像分析揭示了Berea砂岩中超临界CO2微气泡流的迁移特征

摘要 在本研究中，使用相同的 Berea 砂岩样品进行了两次超临界 CO2 (scCO2) 注入实验（微气泡流动注入 (MBI) 和常规流动注入 (CI)），以研究微气泡流的独特输运特性。利用X射线计算机断层扫描(CT)成像研究了空间CO2饱和度(S CO 2 )的四维特征及其与空间孔隙度的关系。结果表明，微气泡流比常规流具有更强的波及效率，最终导致更高的S CO 2 。根据饱和度分布统计，MBI可以提高孔隙空间利用率，尤其是在中等孔隙度空间。几个 CO2 优先流，随着高渗透层迁移，被识别。与CI相比，MBI期间许多局部宏观区域的CO2在孔隙空间中的积累增强，产生了离散的分布方式。这些流动不仅提高了被占据孔隙空间中 CO2 的驱替效率，而且进一步增强了随后从高渗透层到低渗透层的垂直 CO2 渗透。最终的实验结果表明，CO2微气泡流在吹扫和驱替方面的双重优势可以有效提高CO2封存能力。这些流动不仅提高了被占据孔隙空间中 CO2 的驱替效率，而且进一步增强了随后从高渗透层到低渗透层的垂直 CO2 渗透。最终的实验结果表明，CO2微气泡流在吹扫和驱替方面的双重优势可以有效提高CO2封存能力。这些流动不仅提高了被占据孔隙空间中 CO2 的驱替效率，而且进一步增强了随后从高渗透层到低渗透层的垂直 CO2 渗透。最终的实验结果表明，CO2微气泡流在吹扫和驱替方面的双重优势可以有效提高CO2封存能力。