AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Exploring for Tight Oil in the Pennsylvanian Cleveland Sandstone on the Nemaha Ridge Using High Resolution 3-D Seismic and Stratigraphic Analysis: A New Play in an Old Area
(1) Fossil Creek Resources, LLC, Arlington, TX.
Although an active development target in the panhandles of Texas and Oklahoma, the Upper Pennsylvanian Cleveland Sandstone along the Nemaha Ridge of north central Oklahoma and south central Kansas has traditionally been viewed as a shallow (2,500’-3,000’), tight oil “teaser” or tertiary objective on the way down to other more economic objectives since the 1920’s. Much of the areal extent of the Cleveland is too thin and tight to be produced economically. However, by integrating high-resolution 3D seismic and detailed sequence stratigraphic analysis, thicker, productive Cleveland reservoir fairways can be identified and drilled economically on the Nemaha Ridge.
Cleveland depositional systems in the Nemaha Ridge area include river-dominated deltas and incised valleys, each with distinctive log and seismic characteristics. Deltaic reservoir successions occur in the upper two thirds of the Cleveland interval and are usually the best reservoirs. The deltaic reservoir units are composed of very fine to fine-grained sanding upward successions exhibiting dip-elongate behavior and rapid changes along strike. Cleveland valleys in the study area are blocky to fining-upward, lower medium to very fine grained units that occur in the lower part of the Cleveland succession.
Optimal drilling locations are best identified by fine-scale correlations and seismic mapping, linked to subtle syn-sedimentary tectonics. High-resolution 3D seismic (up to 1.4 million traces per square mile) has proven a key tool in differentiating and predicting optimal reservoir trends in this new play concept on the Nemaha Ridge.