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High-Resolution Stratigraphic, Biostratigraphic, Petrophysical, and Geochemical Analysis of the Lower Carboniferous Caney and Late Devonian to Early Carboniferous Woodford and Chattanooga Shales in Oklahoma and Kansas

Watney, Willard L.1; Boardman, Darwin R.2; Doveton, John H.1; Newell, Kerry D.1; Cruse, Anna 2; Thompson, Thomas L.3; Puckette, James O.2; Victorine, John R.1; Stalder, Kenneth 1; Walton, Robert 4; Franseen, Evan 1
1 Kansas Geological Survey, University of Kansas, Lawrence, KS.
2 Boone Pickens School of Geology, Oklahoma State University, Stillwater, OK.
3 Division of Geology and Land Survey, Missouri Department of Natural Resources, Rolla, MO.
4 Cicaco, Camarillo, CA.

Integrated geoscientific studies of shale cores from the northern Midcontinent are being conducted to establish a temporal-spatial framework of rock properties. Biostratigraphic, petrophysical, geochemical, and sequence stratigraphic approaches are being used to understand local, regional, and global controls on Late Devonian-Early Carboniferous Woodford and Chattanooga shales and the Lower Carboniferous Caney Shale, and establish relationships to the adjoining carbonate shelves. An objective is to provide strategies to target and develop remaining oil and gas resources harbored in these shales and adjoining carbonate margins.

Cores taken along the northern margin of the Anadarko Basin in southern Kansas and the southwestern part of the Arkoma Basin in Oklahoma are described at cm-scale, and augmented by SEM and thin-section petrography. Descriptions are combined with interpretations from formation imaging, spectral gamma, and neutron-density porosity logs to establish a sequence stratigraphy in these deep-water deposits. Common sampling points for the biostratigraphy and geochemistry were established using this stratigraphic framework.

Meter- to decimeter-scale depositional sequences compose distinctive stratal successions representing a range from oxic to euxinic conditions. Sequence boundaries are sharply defined. Boundaries are commonly scoured surfaces with basal beds including phosphate nodule lags and lenticular and often cross-laminated detrital silt. Sediment condensation follows, characterized by organic- and uranium-rich, phosphatic and pyritic hard dark-gray shales with pelagic fauna dominated by radiolarians. The condensed section is overlain by less organic-rich green or gray claystone or silty claystone often containing benthic fauna, trace fossils, and pellets. This regressive lithofacies is characterized by high Th/U ratios, attributed to residual, alumina-rich clays. These claystones in the Caney Shale are notably soft. Siltier clays in the Woodford are hard and exhibit discontinuous microfractures. Abrupt contacts between condensed and regressive lithofacies, particularly in the Caney Shale, suggest forced regression.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009