Estimation of CO2 saturation from time-lapse CO2 well logging in an onshore aquifer, Nagaoka, Japan

摘要: The first Japanese pilot-scale CO2 sequestration project has been undertaken in an onshore saline aquifer, near Nagaoka Niigata prefecture, and time-lapse well logs were carried out observation wells to detect the arrival of injected evaluate saturation reservoir. was into a thin permeable zone at depth 1110 m rate 20?40 tonnes per day. total amount 10 400 tonnes, during injection period from July 2003 January 2005. demonstration allowed improved understanding movement porous sandstone reservoir, by conducting geophysical three wells. Comparison between neutron logging before after insertion fibreglass casing OB-2 showed good agreement within target formation, higher concentration shale volume reservoir results bigger difference two results. breakthrough identified induction, sonic, logs. By sonic logging, we confirmed P-wave velocity reduction that agreed fairly with laboratory measurement on drilled core samples site. We successfully matched history changes estimated three. sonic-velocity matching result suggested sweep efficiency about 40%. Small effects resistivity resulted small induction when partially saturated. also found CO2-bearing responded suspension injection.