Study on the effect of pore-scale heterogeneity and flow rate during repetitive two-phase fluid flow in microfluidic porous media

Various energy recovery, storage, conversion and environmental operations may involve repetitive fluid injection thus, cyclic drainage–imbibition processes. We conducted an experimental study for which polydimethylsiloxane (PDMS)-based micromodels were fabricated with three different levels of pore-space heterogeneity (coefficient variation, where COV = 0, 0.25 0.5) to represent consolidated and/or partially sandstones. A total 10 injection-withdrawal cycles applied each micromodel at two flow rates (0.01 0.1 ml min −1 ). The results analysed in terms morphology, sweep efficiency, residual saturation, the connection fluids pressure gradient. pattern invasion displacement non-wetting converged more readily homogeneous model (COV 0) as process continued. overall efficiency between 0.4 0.6 all tested rates, regardless this study. In contrast, effective was observed increase higher lower rate, while that trend became reversed rate. Similarly, saturation largest 0 but it opposite flow-rate case. However, Minkowski functionals boundary length connectedness remained quite constant during flow. Implications porous media-compressed air storage (PM-CAES) are discussed a complementary analysis end paper. Supplementary material: Figures showing distribution water (Fig. S1) oil S2) drainage imbibition step microfluidic pore-network models available https://doi.org/10.6084/m9.figshare.c.5276814 Thematic collection: This article is part Energy Geoscience Series at: https://www.lyellcollection.org/cc/energy-geoscience-series