Paleozoic source rocks and crude oils from the Anadarko basin, Oklahoma, have been characterized by means of a variety of organic geochemical techniques. The potential source rocks investigated include the Viola Group, Sylvan Shale, Lower Mississippian limestone, Chester group, Springer Formation, and Morrow group. The Woodford Shale, which is an important source rock in the basin and has been discussed extensively in the literature, was used as a laboratory standard in this study. The crude oils examined in this study were obtained from reservoir formations of various ages from throughout the basin.
The source rock screening analysis indicates that the lower and middle subfacies of the Viola, especially from the southeastern part of the basin, have substantial oil-generation potential. The Sylvan is not a source rock, although the black shales in the Springer and Morrow have substantial oil- and especially gas-generation potential. The results of this study support the proposal for multiple sources of oil and gas generation in the Anadarko basin.
Selected source rock and oil samples were characterized in more detail, and the distributions and concentrations (both relative and absolute concentrations) of biomarkers in different source rocks and oils were determined. The biomarker characteristics were combined with other geochemical and geological data to interpret the sources, depositional environments, diagenesis and catagenesis processes, migration, and weathering. Oil–source rock correlations were made between source rocks and a number of crude oils based on quantitative and qualitative biomarker distributions.
Petrographic descriptions and graptolite reflectance measurements were used to evaluate petrographic properties of source rocks and maturity levels of the Viola rock. There was a reasonable correlation between measured graptolite and predicted vitrinite reflectance values.