Enhanced coal bed methane (ECBM) recovery: Optimization of CBM production using different injected gas composition and rate for south sumatra CBM field, Indonesia

Indonesia, whose 453 TCF potential coal bed methane (CBM) reserves, rank the 6th largest CBM reserves around the world. However, the technical limitation is amongst the major issues slowing down the exploitation progress of the resources which current national CBM production only reach up to 1 MMSCFD. This paper provides a newly enhanced coal bed methane (ECBM) recovery method to improve the methane production. Scenarios of nitrogen (N2) and carbon dioxide (CO2) injection were used in this study to perform 25 years production simulation and compared with CBM primary production. Created hypothetical model based on the characteristic of coal seams CBM field in South Sumatra, Indonesia, was used to analyze the increasing methane production by using N2 and CO2 injection with different compositions and rates. The result observed about 3,52% incremental methane production by injecting N2 into CBM reservoir. In other words, this new method has an impact on enhancing the CBM national production, particularly South Sumatra CBM field, which could be useful for further CBM development in Indonesia. Mixture injection seemed to be unfavorable for the field due to the difference of gas mechanism.