Pore Space Deformation and Its Implications for Two‐Phase Flow Through Porous Media: A Micro‐Scale Experimental Investigation

Abstract

Geomechanical deformation, which is mainly caused by the pore pressure variation induced by fluid extraction or injection, is commonly observed in environmental and petroleum subsurface systems. As the effective stress varies, the porosity and absolute permeability of the rock may change owing to the distortion and volumetric changes in the pore space induced by the grain movement (David et al., 1994;Dong et al., 2010;Fatt & Davis, 1952;Gray & Fatt, 1963). Meanwhile, the multiphase flow in the pore space may also be impacted. For instance, the threshold capillary pressure, which is the entering pressure required for one phase to enter a pore and displace other phases, and the effective permeability of each phase are all strongly affected by changes in the pore size and shape (Tiab & Donaldson, 2015). Moreover, the competition between the non-wetting phase displacement and the trapping mechanisms is significantly influenced by the aspect ratio, that is, the ratio of the pore size to throat size, which can likewise be affected by the stress conditions (Blunt, 2017;Yu & Wardlaw, 1986). Hence, understanding the impact of pore space deformation on multiphase flow in porous media is of great significance for various engineering processes that involve fluid flow in the subsurface, such as hydrocarbon recovery, groundwater remediation and management, CO 2 geosequestration, and hydrogen storage.Over the last few decades, numerous experimental studies have been dedicated to exploring the variation in relative permeabilities at different stress conditions. To simplify their experiments, the majority of the investigations to date measured the relative permeabilities by increasing the hydrostatic confining pressure (total stress) while the pore pressure was fixed (

Flow Patterns and Pore Structure Effects on Residual Oil during Water and CO2 Flooding: In Situ CT Scanning

“…Therefore, understanding the mechanisms behind water flooding and carbon dioxide flooding is essential for developing and adjusting oil recovery strategies. In researching issues to improve ORR s, understanding the microscopic formation and distribution of residual oil, along with controlling factors, is the most crucial aspect, and of these factors, the pore structure of the reservoir plays a significant role. − …”