4D seismic modeling and CO₂ pressure-saturation inversion at the Weyburn Field, Saskatchewan

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• 作者：Mark A. Meadows ; ^{mmeadows@chevron.com} ; Stephen P. Cole
• 关键词：4D ; Seismic ; Impedance ; Pressure ; CO2 ; Saturation
• 刊名：International Journal of Greenhouse Gas Control
• 出版年：2013
• 出版时间：June, 2013
• 年：2013
• 卷：16
• 期：supp_S1
• 页码：S103-S117
• 全文大小：9819 K

文摘

We present results of our 4D (time-lapse) seismic data processing, impedance inversion, CO₂ pressure-saturation inversion, and uncertainty analysis for the Weyburn Field, Saskatchewan. Such information can be vitally important for identifying CO₂ leaks outside the reservoir, tracking pressure fronts and CO₂ saturation levels over time, and improving the accuracy of flow simulations and history matching to production data. After co-processing multiple vintages of prestack and post-stack seismic data, we calculated time-lapse impedance changes and used them to invert for changes in pore pressure and CO₂ saturation occurring within the Weyburn reservoir over a six-year period. We used a novel inversion approach whose results are consistent with both the petrophysical model and Weyburn reservoir flow simulations. Pore pressure and CO₂ saturation increases of up to 8-9 MPa and 90-100 mole % , respectively, were found near CO₂ injection wells at the Midale reservoir level, with corresponding uncertainties of 4.5 MPa and 30-35 mole % CO₂. For future CO₂ monitoring, we recommend: (1) acquiring high-fidelity, long-offset seismic data for improved P- and S-impedance inversion, (2) measuring ultrasonic core velocities at low effective pressures where seismic data are most sensitive, and (3) establishing uncertainties in input data used for pressure-saturation inversion and uncertainty analysis.