Multiple-Level Tectonic Control of Coalbed Methane Occurrence in the Huaibei Coalfield of Anhui Province, China

Abstract

The Huaibei coalfield is an important coal base and one of the hot spots of coalbed methane development in China. Therefore, a detailed understanding of gas occurrence in the Huaibei coalfield is of great significance. This paper analyzes the gas occurrence from the perspective of multiple-level tectonic control, i.e., the regional tectonic level, the coalfield tectonic level, the mining area tectonic level, and the coal mine tectonic level. This study deduces that gas occurrence in the Huaibei coalfield is characterized by multiple-level tectonic control. At the regional level, the Huaibei coalfield is located in the southeast margin of the North China plate, affected by the tectonic evolution of the North China plate and by the evolution of the Dabie–Tanlu–Sulu orogenic belt. Therefore, the regional geological tectonic is complex, leading to the high gas content and serious gas hazard. At the coalfield level, gas occurrence in the Huaibei coalfield is controlled by east–west faults, NNE faults, and the Xuzhou–Suzhou arc nappe tectonic, which results in the highest gas occurrence in the Suxian mining area, followed by the Linhuan mining area and the Suixiao mining area, while the lowest amount of gas occurs in the Guoyang mining area. At the mining area level, considering the Suxian mining area as an example, the gas occurrence is controlled by the distance from the Tancheng–Lujiang fault zone and the intensity of tectonic compression, i.e., coal mine gas in the east is the highest, followed by coal mines in the south, while coal mine gas in the west is the lowest. At the coal mine level, gas occurrence is controlled by the buried depth of the coal seam, the tensional normal fault, magmatic activity, and uplift and erosion of strata. Finally, the findings of this study may help in the prevention of gas hazard and the exploration and development of coalbed methane in the Huaibei coalfield and other coalfields of similar geological characteristics.