Characterization of Coal Pore Structure and Matrix Compressibility by Water Vapor Injection

In China, the exploration and development of low-rank coalbed methane (CBM) resources are in the early stage, and in-situ pyrolysis is an effective technology for mining of low-rank CBM resources. In this paper, N 2 adsorption method and high-pressure mercury injection test were used to study the pore structure characteristics of coal samples by water vapor injection, and the pore size boundaries of the two test methods were determined. From the continuous pore space distribution model, Frenkel–Halsey–Hill model, Menger sponge model, a new method of pore size classification is proposed: (I) (> 10,000 nm), (II) (1000–10,000 nm), (III) (100–1000 nm), (IV) ( x (pore diameter boundary)–100 nm), (V) (10– x nm), (VI) (