Pore Structure Characterization of Shale Using Gas Physisorption: Effect of Chemical Compositions

In this study, the pore structure characteristics of Canadian Horn River basin shales with various chemical compositions were evaluated using gas physisorption analyses. The samples used in this research were obtained from two different regions (shallow and deep regions) of rock cuttings during the drilling of the shale gas field located in Horn River basin. The pore size, specific surface area, total pore volume, micropore surface area, and micropore volume of the shale samples were measured using both nitrogen and CO2. The results indicated that the pore size was not a function of chemical composition, while distinct trends were observed for other macroscopic and microscopic pore-related properties. In particular, the greatest specific surface area and total pore volume were observed for silica-rich carbonate shales, while clay-rich siliceous shales exhibited the greatest micropore volume and micropore surface area. The trends clearly suggested that macroscopic and microscopic pore-related properties of the Canadian Horn River basin shales were closely related to their chemical composition. Furthermore, a stronger correlation was observed between the quartz content and the micropore-related physical properties of shales (i.e., the micropore surface area and micropore volume) in comparison to other properties.