Oils and hydrocarbon source rocks from the Anadarko Basin in Oklahoma have been studied extensively for many decades, and results from multiple studies have been published. The major source rock in the basin is the Upper Devonian Woodford Shale, although there are several other source rocks that have contributed to oils in the basin. The adjoining Marietta Basin, although of similar age and containing many of the same formations that are present in the Anadarko Basin, has received relatively little attention, and limited geochemical data have been published on the Woodford Shale and Viola Limestone in the Marietta Basin. This study focuses on the geochemical characterization of a Woodford core and 19 produced oils from the Marietta Basin.

The Woodford Shale has excellent hydrocarbon source potential in the Marietta Basin, but it is not the sole source of all of the oils. Geochemical evidence shows that many oils are mixtures of Upper Devonian Woodford and Ordovician Viola sources. Viola oils and rock extracts have very characteristic geochemical signatures, including a pronounced odd/even n-alkane distribution in the n-C₁₀ to C₂₀ range, the presence of methylhopanes, and the presence of 1,2,8-trimethylphenanthrene that is virtually absent from the Woodford. It is possible to distinguish oils that are solely sourced from the Woodford from those that are mixtures based on these characteristics. Information such as this will be invaluable for future exploration efforts, with the knowledge that the majority of oils in the basin are mixtures rather than being sole sourced.