OUTCROP DERIVED INORGANIC GEOCHEMISTRY OF THE WOODFORD SHALE; MURRAY COUNTY; OKLAHOMA

Recent advances in Hand-Held X-Ray Fluorescence (HH-XRF) technology allow for the investigation of inorganic whole-rock geochemistry in the characterization of the Woodford Shale Formation in the Hunton Anticline Quarry (HAQ) of Murray County, Southern Oklahoma. By comparing chemostratigraphic profiles, lithostratigraphic descriptions, and gamma ray response, it is possible to interpret relative changes in water depth, sediment input, and depositional redox conditions. These parameters are essential in characterizing the unconventional Woodford Shale Reservoir.

Data from the Middle Woodford indicate an increasingly reducing, low energy and restricted depositional environment through time. This is reflected in mineralogical shifts with decreasing detrital input and carbonate content. These interpretations are based on elemental concentration fluctuations measured with a HH-XRF. Zr (13 – 100 ± 3ppm), Ti (300 – 2600 ± 70ppm), and Si (9,700 – 71,000 ± 500ppm) are useful in determining provenance and are concentrated in detrital components. Similarly, K (1000 – 2400 ± 250ppm) and Al (250 – 1900 ± 200ppm) are both concentrated in clays, and Sr (19 – 560 ± 3ppm) and Ca (traces – 140,000 ± 200ppm) in carbonate material. Elemental concentrations also reflect redox conditions at time of deposition with increasing V (40 – 1,600 ± 35ppm) levels indicating suboxic to anoxic environments, and Mo (16 – 320 ± 3ppm) anoxic to euxinic ones. Stratigraphic descriptions provide information on the source material, depositional processes, and energy of the system. Finally, recording the GR response of the outcropping Woodford allows for correlation to subsurface well logs. These interpretations will facilitate the potential for high-resolution modeling of the Woodford Shale Formation.