New insights into the beneficial use of coalbed-associated water: A feasibility study of co-produced water reinjection to coalbeds

Coalbed methane development is accompanied by the emission of a large amount of associated water that is rich in chemical substances. If the water is improperly treated, it poses a great threat to the ecological environment and human health. Therefore, it is of great importance to manage the produced water. In this paper, the feasibility of reinjecting coalbed production water into primary coalbed is studied. We applied the reservoir numerical simulation to study the effects of water injection method, water injection volume, water injection position and water injection timing on gas production. The results of a case study show that while injecting 16,869 m3 of water, it can also increase gas production by 15,032 m3. This study prove that the reinjection of produced water into original coalbed to achieve water storage can also increase gas production.