Reservoir Characteristics of the Springer Shale in the SCOOP Play of the Eastern Anadarko Basin, Oklahoma.
A recent surge in horizontal drilling has occurred in the SCOOP (South-Central Oklahoma Oil Province) play in the eastern Anadarko Basin of Oklahoma. Exploration and development in the play horizontally target the condensate and oil windows of the prolific Upper Devonian Woodford Formation. In addition, a younger, shallower target, the Carboniferous Springer Shale, has been identified and is now being developed within SCOOP. To date the detailed lithology, depositional dynamics, and reservoir characterization of the target interval in Springer lacks significant investigation and synthesis. Due to high initial production rates, shallow initial declines, and the historically conventional nature of Springer production some have doubted that the target reservoir is an unconventional shale reservoir. The relatively clean gamma ray signature is also uncharacteristic of most organic rich intervals. A multi-well study was conducted in and around the area of horizontal drilling activity in southeastern Grady, southwestern Garvin, and northeastern Stephens counties, Oklahoma. Rotary sidewall cores were obtained in five wells and whole core from one well in the Springer Shale target zone. A wide suite of core analysis was performed including TRA permeability and porosity, TOC/RE, XRD, XRF, X-Ray CT imaging, FIB-SEM 3D imaging, and whole core/thin section lithologic description. Core analysis results indicate that the Springer Shale target interval is an organic rich, siliceous to argillaceous shale with both a biogenic and clastic component. The dampened gamma ray signture can be attributed to a distinctly reduced thorium and relatively low uranium concentrations. Phosphatic particles, foraminifera, radiolaria, and sponge spicules are common throughout the silica and clay dominted matrix and indicate deposition in an open marine environment. Total organic content varies from 2%–12% and is well disseminated across a highly interconnected organic porosity network that may be partly responsible for the high permeability to oil demonstrated by its robust IP rates and sustained production.
AAPG Datapages/Search and Discovery Article #90221 © 2015 Mid-Continent Section, Tulsa, Oklahoma, October 4-6, 2015