Evolution of nanoporosity in organic-rich shales during thermal maturation

• Published in: Fuel (Guildford) Vol. 129; pp. 173 - 181
• Main Authors: Chen, Ji, Xiao, Xianming
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2014; Elsevier
• Subjects: Anhydrous pyrolysis; Applied sciences; Carbon dioxide; Energy; Energy. Thermal use of fuels; Equivalence; Evolution; Exact sciences and technology; Fuels; Gas shale; Nanoporosity evolution; Nanostructure; Natural gas; Porosity; Reflectivity; Shale; Thermal maturation; Anhydrous pyrolysis; Thermal maturation; Nanoporosity evolution; Gas shale; Pyrolysis; Shale
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2014.03.058

•Laboratory-matured shale samples were produced by an anhydrous pyrolysis experiment.•Low-pressure gas adsorption was used to characterize the pore structure of laboratory-matured shales.•There are substantial differences in evolution of nanoporosity between organic-rich and organic-poor samples.•Evolution of organic matter-hosted nanopores of gas shales can be roughly divided into three stages. Artificial shale samples with equivalent vitrinite reflectance values (VRo) ranging from 0.69% to 4.19% were obtained from an anhydrous pyrolysis experiment. Microporous and mesoporous characteristics of these samples were investigated by low-pressure nitrogen and carbon dioxide adsorption techniques. The result shows that the nanoporosity (microporosity plus mesoporosity) increases with thermal maturity after the oil window stage, and this increase is attributed to the formation of porosity within organic matter and/or mineral–organic matter groundmass, rather than in the pure clay minerals. By combining the gas generation and porosity evolution of these shales, a general model for formation and development of the nanoporosity is proposed.