Reservoir Characterization in Mississippian Rocks via Seismic Methods, Comanche County, Kansas

Dennis E. Hedke¹, Brian W. Wilhite¹, Rafael Sanguinetti², and Kurt J. Marfurt². (1) Woolsey Operating Co., LLC, Wichita, KS, (2) University of Houston, Center for Applied Geosciences and Energy, Houston, TX  [email protected]

Mississippian reservoirs of Kansas occur in multiple zones, in many cases as sub-unconformity, truncation traps. Prediction of these sub-crop reservoirs and their distributions has been a challenge in part geologically and seismically for decades.

Recent geologic modeling, via detailed sample, core, and log analysis of the Mississippian along the western flank of the Pratt anticline, has shown predictive distribution of objective Warsaw sub-crop facies and associated structure. Cursory and continued exploratory results integrating geology with seismic indicate that further success can be obtained in the refinement of zone prediction and, to an increasing degree, zone porosity of these facies.

P-wave seismic acquisition was commenced in late 2004 to test the viability of imaging details of the sub-crop. The initial survey was processed and analyzed in early 2005 and confirmed the ability to image certain sub-crop characteristics. An expanded survey was designed to incorporate wide-azimuth multi-component data acquisition later that year, and the two surveys were merged and processed for the P-wave solution. Converted shear-wave (C-wave) processing of the second survey followed immediately.

Preliminary analysis of seismic data included conventional time-structure and isochron mapping, and velocity mapping for depth conversion. Subsequently, seismic inversion from amplitude to impedance, porosity estimation, AVO workflows to identify gas content, and multiple-attribute analyses (curvature, coherence, etc.) were focused on various stratigraphic and structural objectives.

It is evident from examination of time slices through the primary reservoir zone that P-wave data and C-wave data offer significantly distinct results, which we believe will be useful in attempting to better understand fracture systems, as well as these challenging stratigraphic systems.