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Pore-Fluid Composition Oriented 4-D Seismic Data Processing and Interpretation: Implications for Monitoring EOR and/or Sequestration CO2

Raef, Abdelmoneam E. 1, Richard D. Miller1, Alan P. Byrnes1, William E. Harrison1 (1) Kansas Geological Survey, Lawrence, KS

 

High-resolution 4D-seismic data used for monitoring small (15% or less) carbonate reservoir fluid changes in carbonates can be very important in an EOR and/or carbon sequestration endeavor. The high-resolution required for successful monitoring necessitates a seismic data-processing flow that balances two competing attributesevent coherency and high-frequency content-in the data undergoing processing for monitoring/mapping pore-fluid changes. In many situations the ability to steer the processing flow toward superb event continuity comes at the expense of preserving invaluable 4D-seismimc signatures related to subtle pore-fluid changes.

 

We advocate tolerating less than perfect event continuity (structural imaging) in pursuit of maintaining a more representative poststack seismic wavelet that, to a great extent, honors pre-stack wavelet characteristics and preserves subtle 4D-seismic signatures. Proper understanding of the interplay among high-resolution data sensitivity to time and phase-shifts, the event continuity-bandwidth trade-off, and the modeled 4D-seismic signature of injected CO2 is crucial to selecting seismic attributes that are responsive to pore fluid. The pore-fluid oriented data processing flow of a pilot timelapse seismic monitoring of injected tertiary EOR-CO2 project at the Hall-Gurney Field in Kansas resulted in successful and enhanced CO2-imaging despite the challenging geological and geophysical setting of the targeted thin (6 m) carbonates composed of an ooid shoal complex that encompasses two to three stacked, shallowing-upward cycles of the Lansing-Kansas City Group. The improvement in CO2- imaging came as a result of adopting a processing flow that emphasizes preserving pre-stack wavelet characteristics, thus enhancing and preserving the reservoir 4D-seismic signature.

 

AAPG Search and Discovery Article #90055©2006 AAPG Rocky Mountain Section Meeting, Billings, Montana