An overview of the Sooner Field
The Sooner Unit is a Cretaceous D Sand stratigraphic play, located in Weld County, Colorado. The reservoir is interpreted to be funnel-mouth estuary and valley fill. By correlating log data, the D Sand reservoir appears to be a series of vertically stacked channels with a maximum gross thickness of 70 feet. Commonly, the channels have a gross thickness of 30 feet or less.
The D Sand individual sands and valley fills have been very difficult to visualize using conventional amplitude data. The following workflow will employ Spectral Decomposition (SD), to resolve this visualization problem.
Seismic resolution of the D Sand in 2d/3dPAK
Survey Spectrum analysis has shown that the dominant frequency for the D Sand is 55 Hz, with a vertical bed resolution (tuning) of approximately 61 feet ((13,500 ft/sec IVEL / 55Hz) / 4). The tuning thickness chart for the Sooner Unit 1-21A illustrates a tuning time thickness of 8 to 9 ms. Therefore, tuning is calculated to be in the range of 55 to 60 feet. The D Sand is located seismically at approximately 1.45 sec. two-way time. Most of the D Sand pay thicknesses are between 30 to 70 feet gross. Therefore, essentially all the net pay in the wells is at or below tuning.
Spectral decomposition of the Sooner seismic volume
The dominant frequency of the Sooner3D seismic volume is 55Hz. The valley fill tuning frequency may be either greater or less than the overall Sooner3D dominant frequency. Spectral Decomposition was run in order to analyze the frequencies of the Sooner3D seismic volume, observe the different bands and examine each band volume.
Spectral Decomposition was performed using Seismic Micro-Technology, Inc. KINGDOM Software and Rock Solid Attributes (RSA) on a seismic interval from one to two seconds. SD Envelope Sub-band Attributes were selected, and the defaults were applied for banding based on a linear scale.
Display spectral decomposition in 3D volumes
The best way to view the individual spectral decomposition volumes is with KINGDOM’s Envelope Sub-Band for 56 Hz (close to the overall dominant frequency for the Sooner3D seismic survey) at the level of the D Sand, approximately 1.456 seconds two-way time, was examined. Little in the way of detail is visible at this band width. Upon examination of the SD Envelope Sub-band for the 32Hz volume, the 32 Hz bandwidth may be construed as the sandier portions of the volume
