Impact of tectonic deformation on coal methane adsorption capacity

Abstract

Tectonic deformation can cause significant changes in the physical and chemical structures of coal by damaging the macrostructure and macromolecular composition. For thorough research on the coal tectonic deformation impacts on gas adsorption capacity, this paper collected and summarized the parameters of experimental adsorption isotherms and coal macerals, conducted proximate and ultimate analyses, and systematically discussed the adsorption properties of different structures of coals and the influence of temperature and pressure on coal adsorption. Furthermore, the semi-quantitative relationships between the structural parameters of coal and its methane adsorption capacity are explored. The results show that (1) due to different tectonic stresses, the molecular and porous structures of different types of tectonic coal exhibit significant differences (e.g. sample N25, which is in a fault zone, has the highest methane adsorption capacity), and (2) coal methane adsorption capacity decreases along with increasing temperature. At a pressure of 12 MPa, primary coal (N32) showed Langmuir volume (VL) values of 15.38, 9.58, and 7.86 cm3/g and Langmuir pressure (PL) values of 3.82, 2.07, and 1.81 MPa at temperatures of 30°C, 50°C, and 70°C, respectively. (3) The Langmuir volume appears to have a linear relationship with parameters ID1/IG, Al/OX, and A-factor, as well as a parabolic curve relationship with fa, thereby illustrating that increases of apparent aromaticity can raise CH4 adsorption on coal.

Investigation of pore structure characteristics and adsorption characteristics of coals with different destruction types

“…Zhao et al. (2019) and Li (2015) obtained the adsorption capacity of the primary structure coal and tectonic coal by a WY-98A gas adsorption constant analyzer at a temperature of 303 K, as shown in Figure 14. As shown in Figure 14, the adsorption quantity increases with increasing adsorption equilibrium pressure.…”

Study on the effect of H 2 S on the adsorption of CH 4 , N 2 and CO 2 by anthracite

“…He et al [11] made a comparative analysis on the difference of adsorption isotherms of CH 4 , H 2 S and N 2 , and concluded that the adsorption capacity of each gas increases with the increasing of pressure and van der Waals force when the pressure is less than 10 MPa. Li et al [12] founded that tectonic deformation have an impact on CH 4 adsorption in coal. Deng et al [13] believed that gas extraction in high-gas coal mines rich in sulfur change the gas partial pressure in coal seams, thus producing hydrogen sul de gas.…”

The characteristics of methane adsorption capacity and behavior of tectonic coal

“…A large number of studies have shown that the research on the complex and exclusive characteristics of tectonic coal not only establishes the basic theory of geological body structure and tectonic changes under the action of geotectonic movement, but also plays an important guiding role in engineering practice such as coal seam outburst risk prediction and underground gas drainage in CBM low-permeability enrichment areas (Pan et al, 2012;Li et al, 2019;Zhang et al, 2022). Based on the long-term research and knowledge in structural composition of organic matter in tectonic coal and coal-methane adsorption through the author's research group (Huan et al, 2015;Zhang et al, 2018;Wang et al, 2021a;Yang et al, 2021), this paper summarizes and prospects the progress made in the study of methane adsorption capacity and behavior of tectonic coal in recent years, hoping to share and communicate, and promote further research on the adsorption of tectonic coal, so as to provide a reference for the prediction and prevention of gas disasters in outburst coal seam and to improve the recovery ratio of coal seam methane.…”