SEGJ Technical Conference


The possibility of monitoring using seismic velosity in CO2-EOR


Abstract
CCUS (CO2 Capture Utilization and Storage) has been introduced and been progressed worldwide recently. Among the various kinds of CCUS techniques, CO2-EOR is the most frequently applied method. In CO2-EOR, oil-production increases due to the increase of oil-mobility by mixing oil and injected CO2, which is called miscible state, and the efficiency of EOR depends on the amount of the miscible part. In this paper, we formulate a way to calculate the amount of individual fluid parts from seismic velocity change theoretically. Then, we apply the methodology to Weyburn site, which is a popular CO2-EOR site. The result indicates that the change due to amount of miscible fluid in oil is small. However, the change depends on rock properties and fluid properties. Thus, the possibility of monitoring using seismic velocity is site specific in CO2-EOR. The methodology is useful for a design of monitoring survey.