시추공이 부재한 CCS 후보지역에서의 중합전 임피던스 역산: 서해 군산분지 사례 연구

초록

In this study, we applied prestack impedance inversion to 3D seismic data from the Gunsan Basin, to quantify elastic properties for a potential CO₂ geological storage site. Because no wells exist in the survey area, low-frequency models for simultaneous inversion were built using logs from a distant well in the same basin. Density logs distorted by borehole washout were corrected using an apparent geometric factor derived from the caliper–density relationship. With the corrected logs, we first performed post-stack impedance inversion to estimate P-impedance and to construct a low-frequency model, and then conducted stepwise prestack inversion to obtain P-impedance, S-impedance, density, and Vp/Vs. The inverted properties show coherent trends within stratigraphic units and Vp/Vs variations linked to lithofacies changes. Prestack inversion results delineate faults and discontinuities clearly, supporting structural interpretation and facies assessment. In future, this workflow can be applied to estimate storage capacity and determine injection well locations in regions lacking wells.

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