Preliminary Results Of Numerical Simulation In A Smail-Scale Co2 Injection Pilot Site : 1. Prediction Of Co2 Plume Migration

In this study, numerical simulation was carried out to predict the behavior of injected CO2 plume. Study site, a small-scale CO2 injection site, is located at Yeongil Bay within the Pohang Basin. Simulation results show that pressure buildup at the injection well and the monitoring point increases in proportion to the increase of residual gas saturation (Sgr), which results in the decrease of storage capacity. Assuming the maximum injection pressure of 140 bar, storage capacity is 41,600 ton, 41,100 ton, and 39,100 ton according to Sgr = 0.05, Sgr = 0.15, and Sgr = 0.25, respectively. Injected CO2 asymmetrically moves to the up-dip direction along the steep slope. However, Sgr also affects the extent of CO2 plume. The migration distance of CO2 plume from the injection well is shorter with the high Sgr value than with the low Sgr value, while CO2 saturation (Sg) is higher with the high Sgr value. This lowers the quantity of dissolved CO2 due to the reduction of the contact area between CO2 and brine. Our results show that, in a given condition, high Sgr condition reduces the storage capacity and the stability of CO2 storage. This study shows the modeling results prior to CO2 injection. Thus it is required to reduce the uncertainty of the model and to correct the model through history matching Nonetheless, our results will be helpful to evaluate the storage capacity and to establish the monitoring plan.