Mapping Tripolitic Chert, Tight Limestone, and Tight Chert by Crossplotting 3D Seismic Inversion Attributes: An example from Osage County, OK
Benjamin Dowdell, Kurt Marfurt, and J. Kwiatkowski
With the advent of horizontal drilling and hydraulic fracturing in the Midcontinent, U.S.A., fields once thought to be exhausted are now experiencing renewed exploitation. However, traditional Midcontinent seismic analysis techniques no longer provide satisfactory reservoir characterization for these plays; new seismic analysis methods are needed to properly characterize these radically innovative play concepts. A raw 3D prestack seismic survey acquired in Osage County, OK is reprocessed, paying careful attention to velocity analysis and residual statics calculations, and is then prestack time-migrated. The use of a robust prestack structure-oriented filter and spectral whitening greatly enhances the results. With a relatively shallow target of approximately 3,000 ft in our study area, the prestack time-migrated seismic data has offsets sufficient to invert for density, which is shown to be the best discriminator for tripolitic chert on well logs. Prestack inversion generates a suite of seismic attribute volumes, which are crossplotted volumetrically between the top of the picked Mississippian and Arbuckle surfaces. Using well control as calibration, polygons are selected in crossplot space, which correspond to tripolitic chert, tight limestone, and tight chert. Geobodies are then extracted and provide a 3D mapping of these three facies encountered throughout the Mississippian section.
AAPG Search and Discovery Article #90176©AAPG Mid-Continent Meeting, Wichita, Kansas, October 12-15, 2013