Potential for Converting Geological CO2 Storage Site into Methane Deposits via Indigenous Microorganisms and Mitigating Storage Overpressure Risks (A Review)

Microbial methanogenesis can potentially mitigate atmospheric CO2 emissions while simultaneously establishing new methane reserves. Natural CO2 fields demonstrate geological stability and are frequently used for enhanced oil recovery. However, anthropogenic CO2 sequestration entails significant safety risks and operational drawbacks. Long-term global CO2 storage generates high-pressure environments, poses leakage risks, and requires extensive monitoring. This review evaluates the potential conversion of CO2 storage site into methane deposits and the mitigation of overpressure risks through the activity of indigenous organisms. Furthermore, the analysis characterizes potential reservoir types, various CH4 production pathways, microbial communities, and microbial survivability under extreme conditions, alongside the side effects of microorganisms and the overall potential of methanogenic technology. Bacterial conversion of CO2 to methane is considered as the most effective sequestration process. Depleted oil and gas reservoirs have been identified as optimal sites for CO2 sequestration and microbial methane restoration, with Methanomicrobiales, Methanobacteriales, and Methanococcales identified as the primary taxa suitable for microbial methane production. Optimized nutritient and substrate delivery can enhance the viability of these organisms under reservoir conditions. Integrating CO2 sequestration with indigenous microorganisms for microbial methane (CH4) production represents an attractive waste recycling strategy. This approach is expected not only to reduce CO2 emissions and environmental impact, but also to expand methane deposits to meet future energy demands.