System and multi-physics coupling model of liquid-CO2 injection on CO2 storage with enhanced gas recovery (CSEGR) framework.

Injecting CO 2 into gas reservoirs can achieve CO 2 Storage with enhanced gas recovery (CSEGR). The development of liquid-CO 2 injection has the characteristics of high injectability, high mobility ratio, and low diffusion coefficient. Therefore, this paper established a wellbore-reservoir-thermo-hydro-mechanical-diffusion (WR-THMD) multi-physics fully coupled model of the wellbore-reservoir system, and verified the model based on field and experimental data. The mass transfer, heat transfer, and gas physical property changes in the wellbore and reservoir during the injection of liquid-CO 2 were studied. The impact of different engineering parameters on improving CH 4 recovery and CO 2 storage is also discussed. The results show that the impact of the wellbore on the physical properties and phase state of CO 2 is crucial. The injection of liquid-CO 2 is beneficial to the storage of CO 2 and the displacement of CH 4. Lowering the injection temperature will slightly improve the injectability of liquid-CO 2 and increase the CO 2 storage rate by 5.13%. Using a high injection mass flow rate will effectively raise CH 4 recovery rate by 15.60%, but it will weaken the injectability of CO 2 and cause CO 2 to break through in the production well prematurely. The research results provide important suggestions and theoretical support for the application of liquid-CO 2 injection on CSEGR. • 3D fully coupled wellbore-reservoir-thermo-hydro-mechanical-chemical (WR-THMD) model is established. • CO 2 physical properties and status in the wellbore are comprehensively analyzed. • Mass transfer, heat transfer and fluid physical properties in the reservoir are comprehensively analyzed. • Effects of injection parameters on CH 4 recovery, CO 2 injection and storage were studied. [ABSTRACT FROM AUTHOR]