The Effectiveness of the Continuous and Cyclic Method on CO<sub>2</sub>-ECBM

Abstract

This study examines the impact of different CO 2 injection methods on coalbed methane recovery. Specifically, this study investigated the effectiveness of continuously injecting CO 2 versus injecting CO 2 that had been soaked for two weeks. The objective was to ascertain which approach was more successful in enhancing CO 2 Enhanced coalbed Methane (CO 2 -ECBM). The experiment involved injecting 3 MPa of CH 4 into dry coal samples, allowing it to adsorb until reaching equilibrium, and then injecting 5 MPa of CO 2 to recover adsorbed CH 4 . The continuous method recovered CH 4 without detectable effluent concentration for 5 hours, but desorption efficiency was only 26% due to fast flow. On the other hand, the desorption efficiency of the cyclic method was only 12%, indicating trapped CH 4 . A comparison of desorption efficiency per unit of time shows the continuous method is more effective than the cyclic method. The results of this study demonstrate the continuous method is more effective for the desorption of CH 4 , and its efficiency can be improved by briefly soaking CO 2 on coal and then reinjecting it to maximize CH 4 recovery. It is advisable to limit the soaking time to prevent excessive swelling of the coal matrix, which can hinder seam flow and harm long-term gas production.