Characteristics of Coal Matrix Compressibility: An Investigation by Mercury Intrusion Porosimetry

• Published in: Energy & fuels 2014-06, Vol.28 (6), p.3673-3678
• Main Authors: Guo, Xiaoqian, Yao, Yanbin, Liu, Dameng
• Format: Article
• Language: English
• Subjects: Applied sciences; Bituminous; Bituminous coal; Coal; Compressibility; Compressing; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fuels; Macerals; Methane; Moisture content; Porosity
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef5004123

Coal matrix compressibility caused by a pressure change is an important parameter in evaluating the permeability change during coalbed methane production. In this study, the pressure-driven coal matrix compressibility for 21 coals in the rank range from high-volatile A bituminous (0.65% R o,m) to low-volatile bituminous (1.77% R o,m) was evaluated by combining the results from mercury intrusion porosimetry (MIP) with N2 adsorption analysis. The pressure interval was chosen to be from 7.35 MPa to ensure that the compression is totally from the coal matrix. The calculated coal matrix compressibility shows a U-shaped relationship with increasing coal rank, and it obtains relatively low values at the medium-volatile bituminous coals. The coal matrix compressibility of high-volatile A bituminous coals is of 1.6398–2.9060 × 10–4 MPa–1, and medium- and low-volatile bituminous coals have coal matrix compressibility of 0.3451–1.5519 × 10–4 and 0.7625–2.5554 × 10–4 MPa–1, respectively. Moreover, with the data of petrographic and proximate analyses, the porosity, moisture content, and macerals have influence on coal matrix compressibility.