Assessing CO2 Storage Capacity of a Steeply Dipping, Fault Bounded Aquifer and Effect of Impurity in CO2 Stream

Abstract

A small scale injection project into an offshore aquifer near shoreline has begun which is seeking the connection with a capture project in Korea. The Pohang basin was selected as a site for a small-scale pilot project and detailed site characterization has been undertaken to establish a geological model for the site since 2013. A potential reservoir for CO2 injection was found at a depth more than 730 meters in the southern offshore part of the Pohang basin from seismic surveys and one exploration well. The seismic interpretation revealed the reservoir is a steeply dip and horizontally fault bounded aquifer. In this study, numerical reservoir simulations were carried out for assessing CO2 storage capacity especially in the dipping reservoir regarding the reactivation pressure of the bounded faults. At the same time, to investigate the effect of impurity in CO2 stream was one of our goals. Captured CO2 streams contain various levels of impurity which vary depending on the combustion technology and CO2 sources. Specifically for geological storage, the non-condensable gases in CO2 streams are not favorable because they can decrease density of the injected CO2 stream and can affect buoyancy of the plume. The effect of the non-condensable gases on storage capacity, injectivity and plume migrations were tested in the reservoir.