Numerical modeling of Gondwana coal seams in India as coalbed methane reservoirs substituted for carbon dioxide sequestration

India has recently witnessed the production of coalbed methane (CBM) on a commercial scale. The analysis of Garg and Shukla (2009) summarizes that initial carbon dioxide storage opportunities should be ventured in CBM sector where the effective cost of the process is partly lowered due to enhanced recovery of methane. This research work was carried out to understand and establish the technical feasibility of CO2 driven enhanced CBM recovery in Indian coals. A regional scale underground coal seam/block was modeled using a commercial reservoir simulator, COMET3. It was found that approximately 218 Mm3 of CO2 can be sequestered in place of 74 Mm3 of CH4 produced from the chosen dimensions of coal block. The changes in fracture gas saturation, matrix CO2 concentration and matrix CH4 concentration with space and time were monitored. Eventually, the numerical values for peak saturation at certain time intervals have been reported. This study is an initial technical estimate for CO2 driven ECBM (enhanced coalbed methane) at a regional scale in India. The results are expected to prove useful not only to reduce India's contribution to greenhouse gases emission into the atmosphere but also to partially meet with the growing energy demand by enhanced recovery of methane from deep, unminable coal seams.

► Critical numerical simulation of storage of CO2 in coal vis-à-vis capture of natural gas.
► Approximately 218 Mm3 of CO2 can be sequestered in the chosen dimensions of Gondwana coal block.
► A total of 74 Mm3 of CH4 can be produced for the period of study (4000 days).
► Monitoring matrix gas saturation, fracture CO2-CBM saturation with space and time.
► A brief review on possible CO2 sinks in India.