AAPG Foundation 2019 Grants-in-Aid Projects

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Regional sequence stratigraphy and rock properties of the Upper Cretaceous Austin Chalk in Texas


Recent industry activity in Texas has extended the Austin Chalk productive trend downdip and along strike, within the Eagle Ford trend. This research will investigate regional correlations of the Austin Chalk and study rock properties to define reservoir, seal, source rock, and mechanical stratigraphy to aid in future exploration and development. Stratigraphic and rock property data will be derived from outcrops, logs, and cores. Lithologic descriptions, hand held gamma ray and XRF tools will tie outcrop to subsurface logs. Regional stratigraphy will be illustrated with a grid of dip and strike sections and structure and isochore maps. Cores and outcrops will be used to constrain facies. Core analyses will include description, XRF, XRD, mechanical hardness, thin sections and SEM images. Ash beds will be collected for high-resolution Pb/U age dating, using Thermal Ionization Mass Spectrometry (TIMS). Facies and rock property observations will be extended using petrophysical analyses of wireline logs. The result will be an integrated regional view of the sequence stratigraphy and paleogeography of the Austin Chalk, tied to rock properties. Initial work shows the chalk has at least four sequences, which show compensational stacking, and the entire interval thins and becomes more organic rich downdip. Units are erosionally truncated updip and over the San Marcos Arch. Since the Austin Chalk is a thick unit (100-900’), and lithology varies considerably vertically and laterally, the regional context is important to optimally target horizontal completions and productive trends.