CO-DEPLOYMENT OF CO₂-EGR AND GEOTHERMAL HEAT EXTRACTION IN GAS INFRASTRUCTURE: A REVIEW

The accelerating global demand for energy, coupled with stringent climate targets, has intensified interest in innovative strategies that simultaneously enhance gas infrastructure performance and reduce carbon emissions. This review critically examines the technical feasibility, operational synergies, and environmental implications of co-deploying Carbon Dioxide Enhanced Gas Recovery (CO₂-EGR) and Geothermal Heat Extraction (GHE) within existing natural gas infrastructure. However, studies addressing their combined deployment as a unified and integrated system remain limited. CO₂-EGR is increasingly recognized as a dual-purpose approach that enhances gas production while sequestering carbon dioxide, thus mitigating greenhouse gas emissions. However, the high compressibility of CO₂ and associated thermodynamic behavior pose challenges to reservoir integrity, wellbore efficiency, and pipeline operations. Conversely, geothermal heat extraction harnesses subsurface heat resources to provide sustainable thermal energy that can optimize gas processing, reduce energy consumption in compression cycles, and improve overall system efficiency.
This review synthesizes recent advances in both technologies, highlighting successful pilot implementations, reservoir modeling developments, and engineering designs that support integrated operations. Key synergies between CO₂-EGR and geothermal systems are identified, including improved fluid mobility through temperature modulation, reduced gas viscosity via heat extraction, and enhanced thermomechanical stability of the reservoir. Critical technical barriers are also analyzed, such as CO₂ phase behavior under geothermal gradients, corrosion and scaling risks in multiphase flow, as well as economic considerations related to capital expenditure and energy pricing. Finally, this review provides a comprehensive foundation for researchers, industry practitioners, and policymakers aiming to unlock the combined benefits of CO₂-EGR and geothermal heat extraction in the transition toward low-carbon energy systems.