CO₂ Gas Permeability and Adsorption of Coal Samples in Consideration of CO₂ Sequestration into Coal Seams

Abstract

It has been clarified that coal seams have a significant ability of CO 2 adsorption more than CH 4 as approximately double based on some experiments reported. By utilizing this property, coal bed methane gas can be replaced with CO 2 injected and produced as a clean energy.The demonstration project has already has been proceeded in North America, Europe and Japan. In Japan, coal seams, where mining is difficult economically, reserves about 18 billion ton, and it has been estimated that CO 2 sequestration into the coal seams has a potential of about 6 trillion m 3 (Koide and Yamazaki 6) ).In this study, measurements of CO 2 adsorption and gas permeabilities of coal specimens have been carried out in order to clarify sensitivities of coal specimen's size on CO 2 adsorption capacity and permeability. Furthermore, adsorption behaviors against saturated CO 2 water have been measured to simulate CO 2 adsorption in a coal seam with high water saturation.Based on measurement results, it was found that the region of about 10 ～ 15mm in depth from a surface where gas supplied abundantly may work for CO 2 adsorption, because the adsorption capacity of the core specimens show about 1 / 2 to 1 / 3 of ones of crushed samples 4mm in size. On the other hand, the adsorption capacity of 4mm crushed coal in the saturated soda water was around 80% of a coal specimen in dry CO 2 gas. KEY WORDS : CO 2 , Sequestration, Coal Seam, Permeability, Gas Adsorption, Saturated Soda Water

Carbon dioxide gas permeability of coal core samples and estimation of fracture aperture width

“…15 with comparisons to previous measurements by Somerton et al (1975) and Sasaki et al (2004). It was shown clearly; especially for Vietnamese coal core samples, that the stress attenuation coefficient for low permeability cores has larger values than those of high permeability cores.…”

“…Gas permeability also is important for estimating of the gas drainage rate or gas recovery ratio from coal seams. However, gas permeability is related to many factors, such as the cleat and fracture systems (Harpalani and Chen, 1997;Olson et al, 2009); porosity, gas pressure and mechanical stress (Somerton et al, 1975;Palmer and Mansoori, 1998;Sasaki et al, 2004); fracture orientation (Laubach et al, 2004). Philip et al (2005) investigated the effect of diagenesis on the initial flow properties of the fracture system, especially with respect to diagenetic effects on the connectivity of the fracture network.…”

“…The simplified relationship between effective stress and permeability for coal cores was presented by Sasaki et al (2004) as follows:…”

Carbon dioxide flow and interactions in a high rank coal: Permeability evolution and reversibility of reactive processes

“…It has been shown that the permeability of coal to gas species is dependent on several factors, including cleat and fracture systems (Harpalani and Chen, 1997;Olson et al, 2009), porosity, type of gas and pressure and mechanical stresses (Somerton et al, 1975;Palmer and Mansoori, 1998;Sasaki et al, 2004), fracture orientation (Laubach et al, 1998), and the effects of matrix swelling/shrinkage induced by gas sorption. The permeability of coal can decrease with an increase in the effective stress (e.g., McKee et al, 1988;Jasinge et al, 2011).…”