4D seismic monitoring of the onshore carbon dioxide injection in Japan

Abstract

Geologic sequestration by carbon dioxide injection is the promising method to mitigate the global climate change due to excess carbon dioxide emission to the atmosphere. At Iwanohara in Nagaoka, onshore Japan, approx 10,000 tonnes of carbon dioxide was injected in the aquifer zone during the period of July 2003 to January 2005 by RITE/METI. In order to monitor injected carbon dioxide, 4D seismic survey was conducted in 2003 and 2005, which was the first 4D seismic monitoring for the carbon dioxide injection to the onshore saline aquifer in the world. 4D anomaly zone caused by possible carbon dioxide saturation effects was identified and mapped in the aquifer zone by several methods. Neural network clustering method was to reduce data redundancy and remnant non-repeatable noises inherent to the onshore 4D seismic data and it turned out to have improved the conventional visual inspection of simple math difference of 3D seismic volume. 3D data were evaluated by well synthetics and impedance inversion to estimate physical parameters and were implemented to both clustering analysis and estimates of physical parameter distribution. Identified 4D anomaly has a spatial correlation with the higher permeability distribution map on the injection zone estimated by baseline 3D volume.