Introduction and Application of the Modified Patchy Saturation for Evaluating CO2 Saturation by Seismic Velocity

AbstractIn the CO2 sequestration projects, aiming quantitative monitoring, it is required to estimate the amount of injected CO2 by seismic velocity. Among various existing monitoring techniques, seismic methods, e.g., seismic reflection, seismic tomography, and sonic logging, are believed as the most promising technique. For this purpose, precise understanding of the relationship between seismic velocity and CO2 saturation is necessary for the quantitative evaluation. In this paper, we present the modified patchy saturation model for the time-lapse monitoring well logging of the Nagaoka project. This model provides more precise relationship between the two properties stated above, compared with existing saturation models. Additionally, we discuss the size of CO2 gas patch in the pore space in relation to the applied seismic wavelength to validate this model