長岡実証試験サイトにおける二酸化炭素挙動モニタリングへの物理検層の適用

概要

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A pilot-scale sequestration of CO2 into an onshore aquifer has been conducted by Research Institute of Innovative Technology for the Earth (RITE) in cooperation with Engineering Advancement Association of Japan (ENAA) . The CO2 injection site is located at Minami-Nagaoka gas field, Nagaoka city, Niigata prefecture, Japan. One injection well (IW-1) and three observation wells (OB-2, OB-3, OB-4) were drilled. CO2 was injected into a thin permeable zone of the reservoir at 20-40 tonnes per day. The CO2 injection started on 7 July 2003, and ended on 11 January 2005 with the total CO2 amount of 10,400 tonnes. The pilot-scale demonstration allowed an improved understanding of the CO2 movement in a porous sandstone reservoir, by conducting time-lapse geophysical well logs at the three observation wells. CO2 breakthrough was identified by induction, sonic, and neutron logs. The sonic P-wave velocity decreased up to 28% at OB-2, and 13% at OB-4. Small effects of CO2 saturation on resistivity resulted in small changes in induction logs when the reservoir was partially saturated.
2008-01-25