An Experimental Investigation of Flow Regimes in Imbibition and Drainage Using a Microfluidic Platform

Abstract

Instabilities in immiscible displacement along fluid−fluid displacement fronts in porous media are undesirable in many natural and engineered displacement processes such as geological carbon sequestration and enhanced oil recovery. In this study, a series of immiscible displacement experiments are conducted using a microfluidic platform across a wide range of capillary numbers and viscosity ratios. The microfluidic device features a water-wet porous medium, which is a two-dimensional representation of a Berea sandstone. Data is captured using a high-resolution camera, enabling visualization of the entire domain, while being able to resolve features as small as 10 µm. The study reports a correlation between fractal dimensions of displacement fronts and displacement front patterns in the medium. Results are mapped on a two-dimensional parameter space of log M and log Ca, and stability diagrams proposed in literature for drainage processes are superimposed for comparison. Compared to recent reports in the literature, the results in this work suggest that transition regimes may constitute a slightly larger portion of the overall flow regime diagram. This two-phase immiscible displacement study helps elucidate macroscopic processes at the continuum scale and provides insights relevant to enhanced oil recovery processes and the design of engineered porous media such as exchange columns and membranes.

Surface Charge Affecting Fluid–Fluid Displacement at Pore Scale

“…With controlled surface coatings on the microfluidic PNS, we observed different displacement patterns of water pushing oil, namely stable displacement, capillary fingering, and viscous fingering, reported in the literature under different experimental parameters. [ 47–50 ]…”

“…With controlled surface coatings on the microfluidic PNS, we observed different displacement patterns of water pushing oil, namely stable displacement, capillary fingering, and viscous fingering, reported in the literature under different experimental parameters. [47][48][49][50] Noncoated PDMS PNS induce dendritic displacement for water pushing oil. For low capillary number (Ca = 9.76 × 10 −6 ), lateral pore filling between up to three neighboring pillar rows occurs.…”

Effect of Surfactant‐Assisted Wettability Alteration on Immiscible Displacement: A Microfluidic Study

“…After each experiment, the micromodels were sequentially cleaned with petroleum ether, acetone, and DI water to remove residuals. To restore the wettability of micromodels, we performed the following cleaning protocol after each experiment: HCl/methanol (1:1), DI water, a base solution (1:1:5 NH 4 OH:H 2 O 2 :H 2 O), also known as RCA clean (SC-1), and DI water (Guo & Aryana, 2019). Then the micromodels were dried on a hot plate at 110°C.…”

Emergence of unstable invasion during imbibition in regular porous media

“…The fluid-fluid displacement process is involved in various engineering applications, such as carbon geosequestration, underground hydrogen storage and fuel cells (Szulczewski et al 2012;Andersson et al 2016;Heinemann et al 2021). Extensive efforts have been made to understand, predict and control the fluid transport process using simulations, experiments and theoretical models (Lenormand, Touboul & Zarcone 1988;Zhao, MacMinn & Juanes 2016;Singh et al 2017;Rabbani et al 2018;Guo & Aryana 2019;Gu, Liu & Wu 2021). A phase diagram of fluid-fluid displacement patterns was revealed in the seminal work by Lenormand (1990), where the three displacement regimesincluding stable displacement, capillary fingering and viscous fingering -were found to be controlled by the capillary number, reflecting the relative importance of viscous force to capillary force, and the viscosity ratio of the two fluids.…”