MEOR-on-Chip: Lab-scale visualization of dynamics and mechanisms in microbial enhanced oil recovery via microfluidic technology

Microbial enhanced oil recovery (MEOR) technology has made significant strides in both theoretical research and practical applications, yet gaps persist in understanding its mechanism. This study utilizes a microfluidic chip to delve into the microbial flooding process, simulating MEOR and employing in-situ monitoring through microscopic visualization. The on-chip microbial flooding experiments feature a composite microbial community which swiftly reproduces using petroleum hydrocarbons as the sole carbon source, producing biosurfactants, organic acids, and biogas with notable emulsification and viscosity reduction effects on crude oil. Microbial flooding, building on primary water flooding, elevates oil recovery by 16.7 %. In-situ imaging examines oil displacement, residual oil morphology, microbial dynamics, and MEOR mechanisms across displacement processes. Conclusions highlight microbial strains' robust growth and metabolite effects, with the composite community enhancing viscosity reduction by 74.1 %. Facilitated by microfluidic technology, mechanistic studies reveal microorganisms' interactions with oil, leading to emulsification and dispersion. Microorganisms primarily utilize petroleum hydrocarbons at the oil/water interface for growth, whilst use dissolved hydrocarbons in the aqueous phase as carbon sources. Microbial transportation in the reservoir during water injection reveals migration patterns across channels and blind ends, underscoring MEOR complexities. These findings enrich MEOR theory and inform future research and application endeavors.