Numerical Simulation of the CO2 Behavior to Obtain a Detailed Site Characterization: A Case Study at Nagaoka Pilot-scale Injection Site

Abstract This paper discusses a methodology for the site characterization of deep saline reservoirs evaluated through dynamic flow simulations. Not only the detailed site characterization techniques, but also the injection and monitoring data are useful for the characterization of geological storage. Adopting the Nagaoka site as a test field, we constructed a geological model based on a seismic attribute data. Core and logging data analyses suggested that the petrophysical properties had facies dependency and heterogeneity. After building a model, we conducted flow simulations by TOUGH2/ECO2N. The model was calibrated by the bottom-hole pressure and breakthrough time at the observation wells. We selected porosity-permeability relationships, vertical/horizontal permeability ratio, and pore compressibility as the parameter for the history matching. For the systematic search of the best matched model, we used design of experience techniques and obtained a best matched model. Using the model, we investigated long-term fate of injected CO 2 up to 1000 years. In this simulation we considered a reactive transport model. These results demonstrated that temporal change of trapping mechanisms at the Nagaoka site.