Impact of Improved Seismic
Resolution and Signal-to-Noise Ratio on Monitoring
Pore-Fluid Composition Changes: CO2-Injection, Hall Gurney Field, Kansas, U.S.A.
Abdelmoneam E. Raef, Richard D. Miller, Alan Byrnes, and William E. Harrison
Kansas Geological Survey, University of Kansas, Lawrence, KS
Time-lapse (4D) seismic
application in reservoir management programs provides valuable information on monitoring pore-fluid changes and mapping areas of bypassed hydrocarbons. Improved
seismic
resolution, higher signal-to-noise ratio, reduced turnaround time, and timely integration of time-lapse
seismic
results will be critical to successful, dynamic reservoir management.
Having subtle pore-fluid seismic
effects in carbonates reservoirs, by virtue of the carbonates' high incompressibility, mandates optimized signal-to-noise ratio and resolution. When great care is taken in designing processing flows related to pore fluid,
seismic
resolution and signal-to-noise ratio can be boosted to allow recognition of
seismic
changes as small as 8-10%.
A processing flow has improved the seismic
resolution by about 15% on time-lapse data used to monitor the pilot tertiary EOR-project at the Hall Gurney Field of Kansas, where the target is Lansing-Kansas City Group Carbonates. This improvement came as a result of raising the
seismic
dominant frequency from around 55 Hz after conventional processing to 90 Hz after a high-resolution tuned processing flow. The improved dominant-frequency-dependent resolution results in less reflection interference, and therefore better
seismic
attribute
sensitivity to pore-fluid effects that otherwise would be subdued.
Signal-to-noise ratio improvements of about 8% compared to a conventional processing flow, lead to enhanced, more consistent CO2-related seismic
signature for the 4D
seismic
monitoring. Successful monitoring of CO2-related changes relied on
seismic
amplitude attributes of high-resolution 4D
seismic
data with an improved signal-to-noise ratio over conventionally processed data. Integrating the 4D-seismic-imaged extension of the CO2-bank with reservoir simulation models resulted in increased confidence supporting necessary modifications to pre-exiting simulators.