The coalbed methane resource is very abundant in Qinshui basin (3.28 × 1012 m3; 114 tcf). The investigation on the upper Paleozoic coalbed methane system is a guide to the exploration and development of coalbed methane. The upper Paleozoic coalbed methane system in the Qinshui basin is sealed by a low-permeability roof and floor strata comprising mudstone, siltstone, and bauxite of the Carboniferous Benxi Formation and the Permian Shanxi and Xiashihezi formations. The overburden is the Lower Permian Xiashihezi Formation and the Upper Permian, Triassic, and Middle Jurassic clastic deposits. The source and reservoir rocks are the Carboniferous–Permian coal seams. The hydrocarbon generation of the source rocks reached its first peak in the Late Triassic. The highest maturity was about Ro = 1.2% under a normal paleogeothermal gradient (2–3°C/100 m; 1.1–1.7°F/100 ft). A tectonic thermal event during the Jurassic and Cretaceous Yanshanian orogeny enhanced the coal maturity and caused a second peak of hydrocarbon generation. Varying igneous intrusions caused the coal maturity to be higher in the southern, northern, and eastern parts of the Qinshui basin instead of the central and western parts. The highest maturity was greater than Ro = 4% in the Jincheng area. The migrated thermogenetic coalbed methane accumulated in the reservoirs in which abnormally high reservoir pressure exists locally under the hydrodynamic drive. Because of the different hydrodynamic background and sealing condition, the distribution of coalbed methane content is inhomogeneous. The reservoir is undersaturated with gas in most areas. Based on the coalbed methane system investigation, we assessed the coalbed methane producibility in different parts of the Qinshui basin, and the major producibility area is in the southern part of the basin.

The Wangying-Liujia depression in the Fuxin basin covers a 20 km² area and has abundant coalbed methane resource with in-place gas resource 51.81 × 10⁸ m³. Compared with the basins where coalbed methane (CBM) development is successful, the recoverable potential of CBM is evaluated in the investigated district. In the Lower Cretaceous Fuxin Formation, the coal seams are thick (averagely 35.21 m – 42.96 m), the coal adsorption capacity is comparatively high with about 18∼34 m³/t, and the gas content is relatively high (8 m³/t – 10 m³/t). Vertical lithological sealing, lateral fault sealing and hydrodynamics are favorable for the preservation of CBM. Thermogenic gas generated at the end of early Cretaceous and Himalayan Orogeny is the main gas source. Secondary biogenic gas generated from the end of the Cretaceous to now increases gas content. All these provide resource basis for CBM development, and the recoverable resources is 15.543 × 10⁸ m³. Though the permeability is low (well test 0.323 md – 0.469 md), coal can be fractured to improve the reservoir permeability. The coal reservoir is saturated gas or oversaturated, and the ratio of critical pressure to reservoir pressure is high (>0.74), which indicates that a little pressure need be decreased to make CBM desorbed from coal matrix and gas production. In one word, there are preferable recoverable potential in Wangying-Liujia depression, especially in the area limited by Piangan F2 fault, Liujia F2 and β_5–2 dike. At present, 17 CBM production wells with 50 000 m³ per day operate in this area.