Comparing High Resistivity Zones in Well Logs in Hydrocarbon Producing Intervals in Continuous Resource Plays of the Eagle Ford Shale, Woodbine Formation and Tuscaloosa Marine Shale in the Gulf Coast Region

Abstract

The Upper Cretaceous Eagle Ford Shale is one of the most active continuous resource plays in the U.S., producing both oil and gas in southern Texas. To the east in Louisiana, the stratigraphically equivalent Tuscaloosa marine shale (TMS) potentially represents a similar depositional environment and petroleum system to the Eagle Ford Shale. Located between these plays in eastern Texas is the industry termed “Eaglebine”, an inter-fingered interval of Eagle Ford Shales and Woodbine Formation sandstones. In order to evaluate undiscovered hydrocarbon resources in these three plays, cross sections and analysis of resistivity logs from wells in south Texas, northeastward through the east Texas basin and Sabine uplift area, and east to Louisiana and Mississippi were examined to compare resistivity in petroleum producing intervals. Well logs that indicate the presence of organic-rich facies and retained oil-in place within the Eagle Ford Shale, Woodbine Formation, and TMS were analyzed. In the Eagle Ford Shale, resistivity in oil- and gas-bearing intervals generally exceeds 50 Ω-m and can be as high as 200 Ω-m in hydrocarbon producing zones. In the Tuscaloosa marine shale, resistivity ranges from 5-7 Ω-m, significantly lower than observed in the Eagle Ford Shale. In the Eagle Ford Shale, recent studies demonstrate that the Cenomanian facies are the major hydrocarbon producing intervals, rather than the Turonian section as interpreted in the older literature. In the Tuscaloosa marine shale, the stratigraphically equivalent intervals to the Eagle Ford Shale and “Eaglebine” primary oil-producing intervals remain uncertain. Our objective is to determine the section of the TMS that is stratigraphically equivalent to the major oil-producing zone of the Eagle Ford Shale.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016