Time-lapse seismic modeling for CO2 sequestration at the Dickman Field, Kansas



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Time-lapse seismic modeling is often used to study hydrocarbon reservoirs, especially for those undergoing injection or production. The Dickman field, Kansas, provides two possible CO2 sequestration targets: a regional deep saline reservoir (the primary objective) and a shallower mature, depleted oil reservoir (secondary). The work in this dissertation characterizes and simulates monitoring of CO2 movement before, during, and after injection including fluid flow paths, reservoir property changes, CO2 containment, and post-injection stability. My seismic simulation for time-lapse CO2 monitoring was based on flow simulator output over a 50-year injection and 250-year simulation period. This work introduces a feasible and reliable regridding technique that resolves different scales from geological modeling, flow simulation, to seismic modeling for a realistic carbonate geological model. Gassmann fluid substitution theory is applied to calculate fluid properties changes before and after injection. For a porous Mississippian carbonate reservoir with average 25% porosity, the P wave velocity can change around 15% with CO2 saturation up to 84%. Seismic simulation was accomplished via PP and PS reflectivity from the Zoeppritz equation, convolutional (1D), acoustic and elastic (2D) finite difference modeling by a flux-corrected transport equation. This work assesses the effectiveness of 4D seismic monitoring in the evaluation of long-term CO2 containment stability through a fault leakage test. A CO2 plume can be detected from the difference on seismic sections with 5 to 10ms time shift at the storage site before and after injection, and was validated by comparison with the prestack field data. Time-lapse flow to seismic modeling is proved to be useful for carbon dioxide sequestration in a hard rock carbonate reservoir.



Time-lapse, CO2 sequestration, Forward modeling