Biomicrodisturbance: Synergy Driven by Living Microbes for Enhanced Heavy Oil Recovery

Microbial Enhanced Oil Recovery (MEOR) research has long focused on metabolites, such as biosurfactants, whose ability to reduce interfacial tension is inherently limited compared to that of chemical surfactants. This study shifts focus to microbial life activities, establishing a dual-mechanism synergistic EOR method for post-thermal near-wellbore reservoirs of ultraheavy oil. We propose and validate the impact of “bio-microdisturbance” on reservoir development, a mechanism operating in the near-wellbore zone after thermal recovery. Using the facultative anaerobic strain Geobacillus WJ-8, we demonstrate that weak aerobic conditions boost biomass 3–4-fold over anaerobic conditions, with enhanced motility and sustained metabolic activity. This generates continuous microscale physical shear on residual oil films, destabilizing the oil–water interface. Crucially, we reveal a synergistic mechanism of ″surfactant-initiated combined physical stripping” when WJ-8 combines with biosurfactant (rhamnolipids). Rhamnolipids preinitiate oil detachment by reducing adhesion work (Wa) via wettability alteration and interfacial tension reduction. Subsequently, active microbes deliver essential physical forces─normal shear (τm,n), enhanced interfacial instability (∇σ), and reduced yield stress (τy)─through flagellar motion, interfacial tubulation, and chemotactic accumulation. This synergy achieves >90% oil film stripping efficiency on 40–60 mesh oil sands, far surpassing individual effects. In an anoxic deep zone, the mechanism shifts to stress-induced bioflocculation for conformance control, establishing a “near-wellbore disturbance-stripping & deep-zone flocculation-profile control” dual-mechanism framework. 2D micromodel experiments confirm that while biomicrodisturbance mobilizes residual oil, mild thermal assistance is critical for production, boosting sweep efficiency from 45.8% to 77.7%. Based on these findings, we propose mild-thermal-assisted MEOR (MT-MEOR) screening criteria requiring “dual-mode” microbial response, synergistic biosurfactants, and optimized timing with mild thermal stimulation. Validated in the Chunfeng Oilfield, this microbe-driven approach offers a sustainable alternative to conventional oil recovery methods by leveraging zonal synergistic mechanisms to enhance efficiency while minimizing environmental footprint.