Multiphysics of carbon dioxide sequestration in coalbeds： A reviewwith a focus on geomechanical characteristics of coal

To reduce the emissions of carbon dioxide （CO2） into the atmosphere, it is proposed to inject anthropogenicCO2 into deep geological formations. Deep un-mineable coalbeds are considered to be possibleCO2 repositories because coal is able to adsorb a large amount of CO2 inside its microporous structure.However, the response of coalbeds is complex because of coupled flow and mechanical processes. Injectionof CO2 causes coal to swell, which leads to reductions in permeability and hence makes injectionmore difficult, and at the same time leads to changes in the mechanical properties which can affect thestress state in the coal and overlying strata. The mechanical properties of coal under storage conditionsare of importance when assessing the integrity and safety of the storage scheme. On the other hand, thegeomechanical response of coalbed will also influence the reservoir performance of coalbed. This paperprovides an overview of processes associated with coalbed geosequestration of CO2 while the importanceof geomechanical characteristics of coalbeds is highlighted. The most recent findings about the interactionsbetween gas transport and geomechanical characteristics of coal will be discussed and theessence will be delivered. The author suggests areas for future research efforts to further improve theunderstanding of enhanced coalbed methane （ECBM） and coalbed geosequestration of CO2.