Enhanced gas recovery techniques from coalbed methane reservoirs
Fundamentals of Enhanced Oil and Gas Recovery from Conventional and Unconventional Reservoirs
School of Engineering
Coalbed methane (CBM) is currently perceived as one of the reliable sources of energy due to its huge gas reserves estimated globally and is currently being exploited in some countries. Coals, in essence, are naturally fractured reservoirs for which two discrete systems of matrix and fracture (cleat) are considered. Similar to other hydrocarbon resources, CBM reservoirs require implementation of increased recovery techniques to provide economically justified rates. This chapter, aimed mainly at introducing enhanced gas recovery techniques in CBM reservoirs, is presented in two general sections. In the first section, it provides an elaborated description on CBM and the factors involved in such reservoirs and follows in the latter section by discussing the productivity enhancement approaches for CBM reservoirs including hydraulic stimulation (hydraulic fracturing, natural fracture stimulation, and proppant placement) and enhanced CBM recovery that is accomplished through injection of a foreign gas into the reservoir.