A Comprehensive Review on Dynamics of Electrical Double Layer Expansion in Enhancing Oil Recovery

Abstract

Low salinity waterflooding (LSWF) has gained prominence as an enhanced oil recovery (EOR) method by exploiting electrical double layer (EDL) expansion to alter wettability and enhance oil displacement in both sandstone and carbonate reservoirs. This review critically evaluates the role of EDL dynamics in modifying crude oil/brine/rock (COBR) interactions through electrostatic mechanisms, with a focus on the effects of brine composition, salinity, and reservoir conditions. Insights from zeta potential measurements and surface complexation modelling (SCM) indicate that EDL expansion increases electrostatic repulsion, promoting a shift toward water-wet conditions and improving oil recovery. Ion-specific effects are discussed, showing that monovalent ions (e.g., Na⁺) are more effective in sandstones, while divalent potential-determining ions (e.g., Ca²⁺, Mg²⁺, SO₄²⁻) play a key role in carbonates. A "thermal resilience window" is identified 50–90 °C for sandstones and above 100 °C for carbonates within which EDL-driven processes are most efficient. By integrating experimental evidence with theoretical modelling, this work offers a comprehensive framework for optimizing LSWF strategies, linking nanoscale electrokinetic behaviour with practical field implementation. The insights offered here advance the scientific understanding of EDL expansion while presenting actionable guidelines for optimizing LSWF in diverse reservoir settings.