Formation resistivity as an indicator of the onset of oil generation in the Woodford Shale, Anadarko Basin, Oklahoma

James W. Schmoker; Timothy C. Hester

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USGS · 70044342

Formation resistivity as an indicator of the onset of oil generation in the Woodford Shale, Anadarko Basin, Oklahoma

James W. Schmoker·Timothy C. Hester

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Abstract

The Upper Devonian and Lower Mississippian Woodford Shale is a black, organic-rich shale that is a major hydrocarbon source rock in the Anadarko basin. With the onset of oil generation, nonconductive hydrocarbons begin to replace conductive pore water in the Woodford, and formation resistivity increases. Crossplots of formation resistivity versus either vitrinite reflectance (R O ) or Lopatin's time-temperature index of thermal maturity (TTI) define two data populations that represent immature shales and shales that have generated oil. The midpoint of the resistivity zone marking the transition between immature and mature shales is -35 ohm-m. The onset of appreciable oil generation in the Woodford Shale of the study area occurs at maturity levels of R O near 0.57% and of TTI between 33 and 48.

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Source-reported bounding extent: 33.62° to 37° latitude; -103° to -94.43° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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James W. Schmoker, Timothy C. Hester. 1989. Formation resistivity as an indicator of the onset of oil generation in the Woodford Shale, Anadarko Basin, Oklahoma. https://pubs.usgs.gov/publication/70044342

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