A pilot test of geological sequestration of CO2 is been performed by RITE in cooperation with ENAA from 2000. The test site is located at the Minami-Nagaoka gas field in Nagaoka city, 200km north of Tokyo. One injection well and three observation wells were drilled. CO2 of supercritical phase was injected into an onshore deep saline aquifer of 1100m in depth. The injection was conducted at the rate of 20 to 40tonnes per day over the 18 month period between 2003 and 2005 with a cumulative amount of 10405tonnes. A series of monitoring consisted of time-lapse well logging, time-lapse crosswell seismic tomography, bottom-hole pressure/temperature measurement, fluid sampling and micro-seismicity monitoring has been successfully carried out to grasp the movement of injected CO2 during and after the injection. History-matching simulation was performed to interpret the measured results. Long-term fate of injected CO2 was predicted using the last model of history matching, implying the location and size of the CO2 to remain almost unchanged from those at the end of injection in the test area over a period as long as 1000years. The monitoring at the test site will be continued until 2007.
