X-RAY COMPUTED TOMOGRAPHY OF CO2 BEHAVIOR IN WATER SATURATED SANDSTONE FOR GEOLOGICAL STORAGE

The CO2 Geological storage is considered as an effective technology for reducing the emissions of CO2 into the atmosphere. CO2 storage is a technically feasible and effective method for CO2 mitigation because it is based on enhanced oil recovery technology, and storage sites hold significant potential(1-3). Currently, field tests for CO2 geological storage are proceeding in many parts of the world. However, the behavior of injected CO2 is still not completely understood. The CO2 storage potential and risk of leakage from reservoirs must be accurately estimated to realize practicable CO2 storage. For this reason, laboratory-scale experimental analysis of the behavior of CO2 injected in sandstone are an important issues. In this study, CO2 distribution and its behavior in sandstone were observed by micro-focus X-ray computed tomography (CT). The X-ray CT can fluoroscope the CO2 in the porous media and reconstruct a three-dimensional CO2 distribution image. A sample was kept under high pressure conditions in a cylindrical pressure vessel and filled with CO2 saturated water. Pressure in the vessel was kept at 7.5 MPa, which is the same condition as a saline aquifer at 750 m depth. Liquid or supercritical CO2 was injected from the end face of water saturated samples. Temperature conditions were set to 20 or 40 degrees C according to the experimental objectives of the CO2 phase. In the experimental results, CO2 distribution in the silica-packed bed and sandstone was clearly visualized with high spatial resolution compared to its diameter. The possibility of improvement in storage technology discussed.