Doddy Abdassah, I Wayan Rakananda S., Dedy Irawan, Irianto P. Binsardo

Petroleum Engineering Department, Institut Teknologi Bandung, Bandung, Indonesia.

As one example of unconventional source of hydrocarbon, coalbed methane is the one of the most developed compared to the other unconventional sources. Started on 1980s, the early coalbed development of coalbed methane production faced some problem such as dewatering time and low recovery factor, but now a technology called enhanced CBM recovery (ECBM) is available with hope to solve those problems mentioned before. Generally speaking, ECBM is divided into two kind of mechanism, the first one is to inject a gas that is adsorbed more on the matrix of the reservoir and the other one is to inject a gas that is adsorbed less. However, due to one unique properties of coalbed methane reservoir, which is its ability to both expand and shrink depending on the amount and the type of gas adsorbed on its matrix, those two ECBM mechanisms has its advantages and disadvantages. This paper will introduce one new method in enhanced coalbed methane recovery that will resolve the problems of both type of ECBM mentioned before by injecting the two different gases in cycle so that the advantages of both method can be achieved with minimalizing their disadvantages.

Keywords: coalbed methane, enhanced CBM recovery, CO₂ sequestration