A Review of Electrically Enhanced Oil Recovery (EEOR): Mechanism, Influencing Factors and Field Application Effects.

This paper presents a systematic review of electrically enhanced oil recovery (EEOR), focusing on the critical gap between its promising laboratory performance and the slow pace of industrial deployment. First, the current state of EEOR applications is reviewed. Although extensive laboratory research has confirmed its technical feasibility, field applications remain mostly confined to pilot-scale projects, particularly in heavy oil and oil sands reservoirs. These trials demonstrate EEOR's potential to outperform conventional steam flooding in terms of recovery efficiency and energy utilization, but they also expose significant challengessuch as low reliability of downhole hardware (with failure rates reaching up to 75% in some projects), geomechanical instability, and operational difficultieshighlighting the technological gap between experimental success and large-scale reliability. Second, the review elucidates the fundamental mechanisms underlying EEOR. As a multiphysics coupled process, EEOR is governed by electrodynamic, electrothermal, and electrochemical effects. Key mechanisms include: electrodynamic effects (electroosmosis and electrophoresis), which provide nonpressure-driven flow forces; electrothermal effects (primarily Joule heating), which reduce heavy oil viscosity; and electrochemical effects (electrowetting and redox reactions), which alter wettability and enable in situ upgrading. A key insight is the inherent interplayboth antagonistic and synergisticamong these mechanisms, with reservoir water salinity serving as the central regulatory factor. The review further discusses emerging technologies, such as electromagnetic-assisted composite flooding and plasma pulse stimulation, emphasizing their potential for synergistic enhancement through multiphysics coupling. Third, economic and operational constraints are critically assessed. Although EEOR may offer energy cost advantages under specific conditions, its commercial viability is hindered by high electricity prices, substantial capital investment, and operational risks arising from equipment failures. Finally, this review outlines a forward-looking perspective. The advancement of EEOR depends on shifting the research focus from mechanism validation to resolving engineering bottlenecks. Future efforts should prioritize the development of highly reliable, long-lifetime downhole electrode and cable systems, the construction of quantitative models capable of predicting coupled multifield effects, and the integration of artificial intelligence for process optimization. Such an engineering-driven approach is essential for transforming EEOR from a promising laboratory concept into a practical, field-deployable technology.