Biodegradation of tar-sand bitumens from the Ardmore/Anadarko Basins, Oklahoma—II. Correlation of oils, tar sands and source rocks

Abstract

In an earlier paper we reported the effects of biodegradation on tar-sand bitumens from the southern part of the Ardmore and Anadarko Basins. In this paper we wish to describe geochemical correlations that have been made between the tar-sand bitumens and oils produced from various formations in the Pauls Valley area, 25 miles to the north. It was determined that the tar-sands were formed from a source similar to many of these oils whose reservoir ages ranged from Ordovician to Pennsylvanian. The oils had been previously divided into two major groups, on the basis of their biomarker distributions, with one group (80% of the oils studied) proposed to have been sourced from the Woodford Shale (Devonian) and the other group from the Viola Limestone (Ordovician). The tar sand bitumen-oil correlation study, based on hydrocarbon and porphyrin biomarker distributions, and pyrolysis-gas chromatography of asphaltenes, has shown that the tar-sand bitumen appears to be genetically related to the group of oils derived from the Woodford Shale and more specifically to those present in the Oil Creek Formation (Ordovician) of the Anadarko Basin.