Combating climate change by mitigation of release of the anthropogenic greenhouse gases has attracted worldwide attention towards research and policy formulations. One such approach utilizes the geological sequestration of carbon dioxide into coal beds which is a value addition process, capable of enhancing the yield of coalbed methane (CBM) in producing reservoirs. CO2 is preferentially adsorbed onto the microporous structure of coal seams and it displaces the methane molecule from the adsorption sites, thereby enhancing the production of the low carbon eco-friendly fuel. In this study, a finite difference based reservoir simulator, COMET3, has been utilized for construction of underground coal bed scenario for Indian seams.

Numerical modeling involves solving complex equations used to describe some physical process by iterative approximate solutions. Such simulation is worked out for underground coal of Lower Gondwana sequence in Jharkhand state in India. Detailed field work was carried out to collect samples and field data. Laboratory tested parameters and some from published data were utilized for construction of the numerical model. The best fit model was developed for estimation of the volumes of gases involved in CO2 enhanced coalbed methane recovery. It also gives a detailed analysis of distribution of gases with time and space.

The results obtained from the simulation are quite encouraging and ascertain that the process of CO2 enhanced CBM recovery seems to be technically feasible for Indian scenario also. The simulation was executed for a period of 20 years to understand the space-time disposition of injected CO2 and recovery of methane from the reservoirs.

It is quantified in this study that for the chosen dimensions of coal block, a total of 15.1 bcf of CO2 can be injected into the reservoir and approximately 5.0 bcf of methane can be recovered.

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