Experimental study of microbial enhanced oil recovery in fractured porous media using the halophilic bacterium Haloferax mediterranei

Fractured reservoirs, comprising over 20% of the world's oil reserves, present significant challenges to enhanced oil recovery (EOR). This study investigates the potential of the halophilic bacterium Haloferax mediterranei in microbial EOR (MEOR) for improving oil recovery in fractured porous media. Experiments using a heterogeneous glass micromodel were conducted at biomass concentrations of 5.07, 6.74, and 10.14 g/L. Results showed that the optimal biomass concentration (5.07 g/L) increased oil recovery by 23% through selective plugging. Higher biomass concentrations caused excessive polymer production, blocking communication pathways between the matrix and fractures, reducing oil recovery to 11.7% and 7.8%. Permeability reductions were evaluated in two core samples, achieving average reductions of 53.5%, 62.5%, and 73.5% for the respective biomass concentrations. Using the optimal biomass concentration (5.07 g/L), oil recovery in two similar core samples increased by 14% and 12.6%. These findings underscore the importance of optimizing biomass concentration to balance permeability reduction and oil recovery efficiency. The study highlights MEOR's potential as a cost-effective, sustainable strategy for enhancing oil recovery in fractured reservoirs. It also provides valuable insights for improving future EOR operations, contributing to global energy resource sustainability.