TITLE:
Water Saturation Dependence on CO2 Sorption Potential of Sandstones
AUTHORS:
Takashi Fujii, Kaori Endo, Satomi Nakagawa, Yoshiyuki Sato, Hiroshi Inomata, Shinsuke Nakao, Toshiyuki Hashida
KEYWORDS:
CO2; Water Saturation; Sorption Potential; Sandstones
JOURNAL NAME:
Natural Resources,
Vol.3 No.2,
June
25,
2012
ABSTRACT: For the assessment of the carbon dioxide (CO2) storage potential of water-filled reservoir rocks (i.e., saline aquifers), it should be first important step for a thorough understanding of the effect of water content on CO2/water/rock interactions during CO2 injection. The purpose of this study is to examine the CO2 sorption amount for Kimachi sandstone and Berea sandstone at different water content using the manometric method at temperature of 50?C and pressures of up to 20 MPa. Our results document that a significant quantity of CO2 was sorbed on the two types of sandstone on all water-saturated bases, which corresponded to the amount adsorbed on the air-dry basis. Also, all the wet samples had significantly higher sorption capacity than the theoretical values calculated from the solubility model based on dissolution of CO2 in pore water and the pore-filling model, which assumes that the pore volume unoccupied by water is filled with CO2. Furthermore, the observations indicated a certain degree of correlation between the sorbed amount and the water content, except at pressures below the critical point for Berea sandstone. This investigation points out that CO2 sorption is a possible mechanism in CO2 geological storage even under water-saturated conditions and that the mechanism of sorption on silica and silicate minerals plays an essential role in the reliable and accurate estimation of the CO2 storage capacity of water-saturated reservoirs.