INTERPRETING EOLIAN RESERVOIR ARCHITECTURE USING BOREHOLE IMAGES
MARY CARR-CRABAUGH, NEIL F. HURLEY, JANINE CARLSON, 1996. "INTERPRETING EOLIAN RESERVOIR ARCHITECTURE USING BOREHOLE IMAGES", Stratigraphic Analysis Utilizing Advanced Geophysical, Wireline and Borehole Technology for Petroleum Exploration and Production, Jory A. Pacht, Robert E. Sheriff, Bob F. Perkins
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Eolian reservoirs exhibit significant compartmentalization and directional permeability caused by the processes taking place during accumulation of sediments within an eolian system. The contrast in grain packing across erosional bounding surfaces is one of the primary controls of fluid-flow patterns within eolian reservoirs. Better prediction of the geometry of flow units bounded by erosional surfaces can be made by reconstructing the type of bedform that formed the accumulation. Subsurface study of the occurrence and the frequency of erosional bounding surfaces has been limited by the availability and quality of core data. However, using borehole images, specifically FMI and FMS logs, the orientation of stratification can be resolved, and the cross-cutting relationships produced by erosional bounding surfaces can be identified. Comparison of the stratification orientation above and below an erosional bounding surface makes it possible to classify the erosional bounding surface within a process-oriented hierarchy. Using the foreset and bounding surface orientations gathered from the FMI and FMS log data, and using computer simulation methods for bedform reconstruction, a bedform that reflects the observed variations in stratification can be constructed.
An integrated study of FMS logs, FMI logs, and cores from the Tensleep Sandstone in the Oregon Basin Field, Bighorn Basin, Wyoming indicates that erosional bounding surfaces can be identified and classified. The FMI and FMS logs also allow delineation of eolian facies such as interdune accumulations.