Review of non-isothermal processes in CCUS from a geomechanical perspective

Abstract

Greenhouse gas emissions have led to severe global climate change, and countries around the world are taking measures to mitigate the greenhouse effect caused by carbon emissions. Carbon dioxide capture, utilization and storage (CCUS) is emerging as a large-scale greenhouse gas emission reduction technology and can potentially become an important means to mitigate the greenhouse effect in the future. There are a series of problems in the implementation of this technology, among which the geomechanical problems due to the thermal effect should not be neglected. This paper summarizes the non-isothermal processes in CCUS and the impacts and hazards caused by the thermal effects of non-isothermal processes. We show that CO₂ injection and sequestration will experience heat exchange with high-temperature formations and wellbores, exothermic dissolution, cooling by the Joule–Thomson effect, exothermic adsorption and exothermic hydrate formation when CO₂ replaces CH₄. These non-isothermal processes can lead to risks including reservoir stability, fault activation and induced seismicity. Thermal effects can also alter reservoir characteristics, such as the effect on CO₂ injection and storage efficiency. This work presents the challenges and future perspectives of thermodynamic studies in CCUS, which will help to fully understand the thermal effects and risks in CCUS and provide a reference for future CCUS operation, monitoring, and research.