Integrated assessment of CO₂-ECBM potential in Jharia Coalfield, India

Coalbed methane (CBM) production is effectively achieved by utilizing two processes, viz. primary and secondary recovery. In this paper, the primary recovery of CBM was studied using the adsorption isotherm while CO₂-ECBM process for the secondary recovery was simulated with realistic parameters. The adsorption isotherm for CH₄ was drawn up to the pressure of 1200 psi for four coal samples and Langmuir isotherm curves for both CH₄ and CO₂ was measured for one sample up to 2000 psi. The adsorption isotherm of four samples was further utilized for finding the primary recovery factor of methane, showing that the average primary recovery is ~ 54% with the highest recovery factor of ~ 76% for one sample. Hence, CO₂-ECBM process could be further implemented to enhance gas recovery. Then, a 3D heterogeneous coalbed model at a depth of 3219 ft was constructed using the COMET3 simulator to demonstrate the potential of CO₂-ECBM recovery technique. A concept of break-even time was introduced in this study for the comprehension of CO₂-ECBM process. It is found that coalbed reservoirs may opt to implement this technology with economically sound recovery.