Coupling Rheology and Capillarity in Surfactant Flooding: Displacement Dynamics for Enhanced Oil Recovery
Year: 2026
Type: article
Abstract: This study presents a comprehensive investigation into the coupled effects of non-Newtonian rheology, capillary forces, and flow dynamics in surfactant flooding for enhanced oil recovery (EOR). A systematic experimental framework was developed using sand-pack flooding under reservoir-representative conditions, with controlled variations in surfactant concentration, temperature, and salinity. The results demonstrate that surfactant solutions exhibit pronounced shear-thinning behavior, leading to a spatially adaptive viscosity distribution within porous media. This behavior enhances injectivity in high-shear regions while improving mobility control and displacement stability in low-shear zones, thereby increasing sweep efficiency. Incremental oil recovery ranging from 11% to 14.6% was achieved, governed by strong multi-parameter interactions. A key finding is the identification of a threshold-controlled transition in capillary number behavior, marking a shift from capillary-dominated trapping to viscous-driven mobilization. Furthermore, the study indicates that the capillary number should be interpreted as a dynamic parameter influenced by both interfacial tension and shear-dependent viscosity, rather than a constant property. Based on these findings, a unified rheology-capillary-flow framework is proposed, providing a physically consistent and predictive basis for optimizing surfactant flooding under realistic reservoir conditions.
Language: English
Subfield: Fuel Technology
Field: Energy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7212376932