A fully coupled gas flow, coal deformation and thermal transport model for the injection of carbon dioxide into coal seams

This paper presents solutions for non-isothermal gas flow coupled with mechanical deformation to evaluate the coupled thermo-hydro-mechanical (THM) processes in coal seams. A non-isothermal case of high temperature CO2 injection is simulated to characterise the complex responses of coal to the injection. The results are compared with those under the isothermal conditions, indicating that temperature has complicated effect on coal properties during the CO2 sequestration process. In particular, high temperature CO2 injection into coal seams reduces adsorption capacity, and the coal matrix swelling caused by gas sorption enhances permeability. The main contribution of this paper lies in providing numerical solutions of challenging flow problems coupled to thermal and geo-mechanical effects in coal seams. Since this model involves the balance of thermal energy and heat transfer, it is applicable of investigating the effects of temperature variation on each term of the effective strain, which helps better understand the CO2 injection processes.