Lecture Notes: Microbial Impact on Petroleum Resources

Microbial Enhanced Oil Recovery (EOR)

• Definition: EOR is a technique to increase the amount of crude oil that can be extracted from an oil reservoir beyond what is achievable through primary and secondary production.

Stages of Oil Production

1. Primary Production

   • Initial phase of extraction.
   • Naturally occurring pressure assists in oil recovery.
   • Only about 10% of the oil is typically recovered.

2. Secondary Recovery

   • Involves injecting water or gas to displace oil towards production wells.
   • Can recover an additional 20-30% of the initial oil (totaling 20-40% with primary production).

3. Tertiary Production (Enhanced Oil Recovery)

   • Focuses on extracting the remaining oil, which can be up to 80% of the total initially present.
   • Includes three major techniques:
     • Thermal Recovery: Injecting steam to reduce oil viscosity.
     • Gas Injection: Increases oil mobility and further displaces oil towards the well.
     • Chemical EOR: Involves using solvents or other chemicals to improve oil mobility.

Microbial Processes in EOR

• Investigating microbial methods as a cost-effective and environmentally friendly approach to EOR.

Examples of Microbial Applications

1. Microbial Paraffin Removal

   • Microorganisms can degrade paraffin (waxy compound in oil), preventing accumulation on production infrastructure.
   • Successfully used in industry, with published effectiveness.

2. Well Stimulation

   • Microbes can produce compounds (acids, solvents, surfactants) that help mobilize oil.
   • Microbial gas production reduces oil viscosity, aiding recovery.

3. Enhanced Water Floods

   • Water flooding often leads to inefficient extraction due to preferential flow paths.
   • Microbial growth can produce biofilms, clogging these paths and redirecting water flow to extract more oil.

Strategies for Implementing Microbial EOR

• Biostimulation: Feeding microbes necessary nutrients or electron donors/acceptors to promote growth.
• Bio-augmentation: Introducing specific microorganisms that are beneficial for oil recovery.
• Combination of Techniques: Biostimulation and bio-augmentation may be used together for enhanced effectiveness.
• Injection of Microbial Products: Instead of live microbes, the products they generate can be injected into the reservoir.

Conclusion

• The lecture highlighted the potential of microbial techniques in enhancing oil recovery and will continue with the discussion on microorganisms in generating natural gas resources in the next lecture.