Ｘ線ＣＴ法による多孔質岩石内ＣＯ２残留ガストラップ現象の分析

Abstract

CCS (Carbon dioxide Capture & Storage) is expected as one of most efficient methods in order to reduce the amount of exhausted CO2 into the air. In the projects, the estimation of storage volume and the assessment of CO2 trapping effect in the reservoir are necessary. The objective of this paper is to analyze the residual CO2 trapping in the porous media after the storage of CO2 in the aquifer by means of X-ray CT. The CO2 injection and successive water injection test were conducted, and the replacement and trapping process of water — CO2 was analyzed by X-ray CT method. Here, the amount of CO2 replaced in the pore during CO2 injection tests was estimated. The amount of residual CO2 trapped in the rock pore during successive water injection tests was also estimated, and relations between the replaced/trapped CO2 and the porosity distribution of rock were discussed. It was found that more CO2 was stored at the relatively high porosity region, and that the residual ratio at the high porosity region easily decreased during the water injection process. However, it was also found that the approximately 10 % of injected CO2 was still remained after the six to ten times pore volume of water was injected into the rock sample.