Coalbed methane (CBM) is one of the unconventional oil and gas resources. The potential of CBM resources in the north of Qinshui Basin is good, but it has not reached the scale of industrial exploitation. CBM mining not only can obtain energy, but also has important significance in reducing coal mine safety accidents and reducing greenhouse effect. In this paper, according to the characteristics of low porosity, low permeability and soft structure of coal reservoirs in the study area, the permeability and desorption of tectonic coal samples collected from different mining areas are measured and analyzed under mechanical vibration. The experimental results show that the low frequency mechanical vibration has obvious effect on the permeability of tectonic coal samples. Increasing the mechanical vibration frequency can promote the large amount of methane desorption in coal reservoirs with more primary fractures and increase the production of CBM. This study can provide a technical reference for the mining of tectonic CBM.
Qinshui Basin is located in the central and southern part of Shanxi Province, China, which is rich in coal reserves and also contains a large amount of coal-bed methane (Zhou, 2013). The northern part of the basin is mainly coal-bearing strata of Upper Carboniferous Taiyuan Formation and Lower Permian Shanxi Formation (Wang et al., 2006). CBM mainly exists in the form of adsorption in the coal body, and its production is a complex process of adsorption/desorption, diffusion/seepage (Yi, 2007). At present, the main methods used to increase production are hydraulic fracturing (Jiang et al., 2016; Johnson et al., 2002; Hou et al., 2022), heat injection (Wang et al., 2015; Wang et al., 2023; Goraya et al., 2019), gas injection (Jessen, et al., 2008; Mazzotti, et al., 2009), vibration (Tanuwijaya, C., & Ariadji, T. 2009; Cui et al., 2024) and other mining methods. In order to explore a technology suitable for the combined extraction of CBM from surface and underground of shallow mid-level tectonic coal in northern Qinshui Basin, the permeability and desorption of tectonic coal samples collected from different mining areas were measured before and after mechanical vibration. The influence of vibration frequency on permeability and desorption of tectonic coal is studied, which provides a technical reference for vibration mining of tectonic coal bed methane.