An analytical solution for geomechanical response of a coalbed to CO2 injection

An analytical solution for geomechanical response of a coalbed to CO2 injection

The sequestration of anthropogenic CO2 in deep underground formations, such as coalbeds, has been proposed to reduce the emission of greenhouse gases into the atmosphere. Coalbeds are favourable because of their ability to adsorb CO2 and because this process can release naturally-stored CH4. Studies have shown that coal may swell and soften as it adsorbs CO2. To enable the estimation of geomechanical response of coalbeds to CO2 injection, we developed analytically found a plane-strain solution which provides the stress and strain distribution around a wellbore during CO2 injection. In this model, the adsorption-induced swelling in coal is considered to be similarly to thermal strains and hence the same mathematical treatments were used. This analytical solution can provide a simplified geomechanical tool which can be coupled with reservoir simulators, where the reservoir characteristics such as permeability are being tied to the geomechanical behaviour.