Evaluation of CO_2 Saturation at Nagaoka Pilot-Scale Injection Site Derived from the Time-Lapse Well Logging Data

摘要

This paper presents a rock physics model describing the relationship between resistivity and CO_2 saturation at the Nagaoka CCS test site in Japan. The target reservoir at Nagaoka is shaly sandstone, thus we applied Waxman-Smits model. For the known observables in the model we used the resistivity log and water saturation derived from the neutron log, with the saturation exponent and the correction value for shale conduction then obtained using time-lapse logging data. Model modification taking the effect of dissolved CO_2 into account was carried out. The analyses provide evidence of successful resildual and solubility trapping currently in progress at Nagaoka.