How Microbes Are Revolutionizing Petroleum Recovery
Imagine trillions of microscopic workers toiling deep underground, steadily pushing valuable oil toward production wells while increasing a reservoir's productivity. This isn't science fiction—it's the reality of Microbial Enhanced Oil Recovery (MEOR), an innovative biotechnology that harnesses microorganisms to recover oil that conventional methods cannot reach.
MEOR offers a sophisticated solution by deploying bacteria and their metabolic products to liberate this trapped oil, representing a fascinating convergence of energy technology and biotechnology that could extend the productive life of oil fields worldwide.
Petroleum extraction occurs in distinct stages, each targeting different portions of the oil in a reservoir:
Involves injecting water or gas to maintain reservoir pressure
Uses advanced techniques like MEOR to recover trapped oil
| Recovery Stage | Method | Typical Recovery Efficiency | Oil Remaining After Stage |
|---|---|---|---|
| Primary | Natural reservoir pressure | 10-20% of OOIP | 80-90% |
| Secondary | Water/gas injection | Additional 15-25% of OOIP | 55-65% |
| Tertiary (EOR) | MEOR, thermal, chemical | Additional 7-15% of OOIP | 35-55% |
Despite these methods, a substantial amount of oil remains unrecoverable using conventional technologies. The challenge lies in the complex physics of oil reservoirs: oil becomes trapped in tiny pore spaces by capillary forces, resisting displacement by conventional water or gas flooding.
Oil reservoirs, once considered sterile environments, are now known to host diverse microbial communities adapted to extreme conditions of temperature, pressure, and salinity 1 4 . MEOR utilizes either these indigenous microbes (stimulated through nutrient injection) or carefully selected exogenous microbes specifically chosen for their metabolic capabilities 4 .
Notable for producing spores that survive harsh reservoir conditions 2 .
Effective biosurfactant producer that reduces oil-water interfacial tension 5 .
Silicate-dissolving bacteria that enhance reservoir porosity 5 .
Effective producers of gases and solvents 7 .
These microorganisms function as nature's reservoir engineers, capable of transforming both the oil properties and the reservoir characteristics to enhance recovery.
Microbes enhance oil recovery through multiple biochemical mechanisms that target both the oil properties and the reservoir characteristics:
Microbes produce biosurfactants—amphipathic molecules that reduce interfacial tension between oil and water 2 7 . This reduction decreases the capillary forces that trap oil in rock pores, enabling mobilization. Studies with Bacillus persicus have demonstrated 33% reductions in interfacial tension, significantly improving oil mobility 2 .
Microbial cells and their extracellular polymeric substances (EPS) can selectively clog high-permeability "thief zones" in reservoirs, redirecting flood water into previously unswept areas 1 4 7 . This biomass redirects displacement fluids into oil-rich regions, improving sweep efficiency.
Microorganisms produce organic acids (acetic, formic, propionic) that dissolve carbonate minerals in reservoir rocks, enhancing porosity and permeability 7 . This creates new flow channels for trapped oil. Bacillus licheniformis, for instance, enhances permeability through acid dissolution 5 .
Microbial production of gases including CO₂, CH₄, and H₂ increases reservoir pressure and causes oil swelling, reducing viscosity and improving flow characteristics 7 . Solvents like alcohols further contribute to viscosity reduction.
Recent groundbreaking research has explored novel microbial approaches for challenging reservoir conditions. A 2025 study investigated silicate bacteria for enhanced oil recovery in low-permeability reservoirs—a significant innovation as such bacteria had never before been applied in MEOR 5 .
Nine artificial low-permeability cores with similar porosity (15.93-17.69%) and permeability (33.0-37.3 mD) were prepared, composed primarily of feldspar, quartz, and mica 5 .
Three bacterial strains (P. mucilaginosus, P. aeruginosa, and B. licheniformis) were cultured separately until reaching concentrations of 10⁸ cells/mL 5 .
The microbial solutions were injected into oil-saturated cores under controlled conditions to simulate reservoir flooding.
Researchers measured changes in porosity, permeability, and oil recovery rates, using μCT scanning to visualize pore-level changes.
Enhanced oil recovery by P. mucilaginosus through biological weathering of silicate minerals 5
Increased core porosity by creating new flow channels 5
| Bacterial Strain | Primary Mechanism | Oil Recovery Enhancement | Key Impact on Reservoir |
|---|---|---|---|
| Paenibacillus mucilaginosus | Silicate dissolution | 6.9% | Increased porosity & permeability |
| Pseudomonas aeruginosa | Biosurfactant production | 7.9% | Reduced interfacial tension |
| Bacillus licheniformis | Acid production | 4.8% | Dissolved carbonate minerals |
MEOR has progressed beyond laboratory curiosity to successful field applications worldwide:
Conducted the first MEOR field test in 1954 in Arkansas, with surveys showing 81% of 322 projects successfully increased production 1 .
Implemented large-scale microbial applications, including microbial wax removal in 1,739 wells at Shengli Oilfield, resulting in 219,000 tons of incremental oil 7 .
Oil & Natural Gas Corporation developed thermophilic bacterial consortia for reservoirs up to 90°C, applying MEOR in more than 125 oil wells with average oil gains of 300 m³ per well 7 .
Reported impressive production increases of 100-200% from microbial applications 7 .
Current research focuses on expanding MEOR applications to increasingly challenging environments:
Recent studies identified Bacillus species capable of functioning at temperatures up to 110°C, potentially enabling MEOR in deeper, hotter reservoirs .
Pilot testing has begun applying MEOR to shale oil formations with historically low recovery factors below 10% 1 .
Researchers are developing optimized combinations of microbes that work synergistically to enhance multiple recovery mechanisms simultaneously 7 .
With its low cost (estimated at less than $10 per incremental barrel), minimal environmental impact, and ability to utilize existing infrastructure, MEOR represents a promising approach for recovering valuable energy resources that would otherwise remain permanently stranded underground 1 3 .
per incremental barrel
As the global energy landscape evolves, these microscopic oil field workers may play an increasingly important role in bridging the transition toward a sustainable energy future while maximizing recovery from existing petroleum resources.