Coalbed methane system of the cretaceous Sahai Formation in the Fuxin basin

The investigation on the coalbed methane system is a guide to the exploration and development of coalbed methane. The source and reservoir rock is the coal seams in the Sahai Formation. The coalbed methane in the Sahai Formation is sealed by the roof comprising mudstone and lutite of the fourth Sahai Formation. The overburden is the fourth Sahai Formation and Fuxin Formation deposits. The hydrocarbon generation of the source rocks reached its first peak in the late Sunjiawan period, and the highest maturity was about R-0=1.3%. The dolerite intrusion during the Himalayan orogeny enhanced the coal maturity and caused a second peak of hydrocarbon generation. In addition, the underwater brought many bacteria generating second biogenic methane. Then the coalbed methane is reserved and a critical moment of the coalbed methane system is at the end of the Late Tertiary. So the coal seams in the Sahai Formation are favorable for coalbed methane exploration and the Dongliang district will be a promising area for coalbed methane exploration.