Characterization of Oil Types Along Hewitt Trend, Carter County, Oklahoma: Implications for Future Exploration

David A. Wavrek

Crude oil production has been significant along the Hewitt trend for over 70 years. Although the area has been considered a mature exploration province, recent success at Cottonwood Creek has generated a high level of interest. An understanding of the oil types, their distribution, and their relationship to the structural development can have a dramatic impact on future success.

Twenty-seven oils from Cambrian-Ordovician to Pennsylvanian reservoirs have been characterized by routine methods of geochemical analysis. The results indicate that three distinct oil types exist, along with oils of intermediate compositions. The oil families correlate to source rocks in the Ordovician, Devonian-Mississippian, and Pennsylvanian sections. Variation in oil chemistry can be attributed to differences in source facies, thermal maturity, and mixing. Development of unconformity surfaces and an extensive fracture system complicate the migration pathways and appear to facilitate the mixing of the different oil types.

The structural development of the Hewitt trend controls the distribution of genetic oil types. The near-identical composition of the Arbuckle (Cambrian-Ordovician) reservoired oil (Devonian-Mississippian Woodford sourced) in both the Cottonwood Creek and Hewitt fields suggests that the oil was emplaced before the movement on the Criner fault separated the fields. If these oils had been subjected to different migration histories, variations would be evident. The distribution of genetic oil types in other Hewitt trend oil fields displays additional characteristics essential to future activity and demonstrates the applicability of geochemistry in mature exploration provinces.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.