Stratigraphic Sequence of Transgressive Barrier Bar Complex and Model for Hydrocarbon Exploration, Red Fork Sandstone, Wakita Trend, Grant County, Oklahoma
Kathleen L. O'Reilly, Paul C. Franks
The Desmoinesian Red Fork sandstone (Boggy Formation, Krebs Group), on the northern shelf of the Anadarko basin, Oklahoma, represents a transgressive barrier bar system. The base of the Red Fork interval is marked by the Inola Limestone (Boggy Formation); the top is marked by the Tiawah ("Pink") Limestone (Senora Formation, Cabaniss Group). Upper shoreface and foreshore deposits, in which porosity and permeability range from 8 to 18% and 0.03 to 9.7 md, respectively, produce significant amounts of oil and natural gas along the east-west Wakita trend. Effective porosity (mainly secondary dissolution porosity) is well developed in these deposits. Successful hydrocarbon exploration requires a solid understanding of the stratigraphic sequences and depositional environments wi hin the barrier system.
Cored sequences, from bottom to top, include: (1) Inola biomicrite, containing brachiopod, trilobite, and echinoderm fragments, and worm tubes (shallow marine); (2) black fossiliferous shale and nonfossiliferous variegated claystone (lagoonal? open marine); (3) coarsening upward sequences of fine to medium-grained sandstone showing low-angle (< 15°) bidirectional cross-stratification and flat laminae (shoreface to foreshore); and, locally, (4) very fine-grained sandstone showing flaser and current-ripple laminae (sand flats). Enclosed in the inferred shoreface or foreshore deposits is a local, 1-ft-thick, flat-laminated, very fine-grained sandstone that may represent washover deposits. Lateral facies equivalents of the shoreface and foreshore deposits include ripple-laminated, very fine-grained sandstone, some of which is overlain by glauconitic siltstone and shale (back barrier or lower shoreface?).
AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.