Flow-Solid-Thermal-Chemical Coupling Model for In-Situ Extraction of Oil Shale Using High-Temperature Supercritical CO₂ 

In situ oil shale development using supercritical CO₂ is a promising method due to CO₂’s low viscosity, high heat, and mass transfer efficiency. This technique allows CO₂ to penetrate micro pores, improve heating efficiency, promote kerogen decomposition, and act as an extractant for crude oil, enhancing oil and gas recovery while being environmentally friendly. Findings indicate that CO₂ injection results in higher oil yield, while water injection produces oil faster. However, considering heat transfer and operation cycles, CO₂ injection is superior. Key parameters influencing thermal recovery include injection temperature, injection displacement, specific heat capacity, perforation interval length, and the number and location of lateral branches. Higher injection temperatures and flow rates, smaller specific heat capacities, and increased and longer lateral branches enhance thermal recovery. The optimal lateral well system identified in this study has a 40 m lateral length and 6 branches, promoting efficient oil shale thermal production. These results provide a theoretical foundation for developing high-temperature supercritical CO₂ in situ extraction technology for oil shale.