Core Interpretation Allows a New Perspective on Tensleep Sandstone Correlations at Teapot Dome Field, Natrona Co., Wyoming

Milliken, Mark D. and Brian Black
Navarro Research and Engineering, Inc, Casper, WY

     Interpretation of core from the Pennsylvanian-Permian Tensleep and Permian Goose Egg Formations has resulted in an upgraded stratigraphic hierarchy at Teapot Dome. In well 48-X-28, 353 ft of core were analyzed and carefully interpreted, including thin section work. The coring project provides data on the sealing character of the overlying Goose Egg rocks, and vertical and horizontal permeability heterogeneities in Tensleep sandstone units. The basal Opeche sandstone of the Goose Egg contains dead oil and is partially fluvial in origin. Its lower contact is a major unconformity on the Tensleep "A sandstone." At Teapot Dome and elsewhere, the Opeche sandstone is often miss-correlated with the Tensleep A sandstone. Core and formation imaging logs have allowed more effective top and base definitions and facies correlations. Some traditional Tensleep units, such as the "B Dolomite", have been redefined to correlate with sequence boundaries. Tensleep outcrops confirm the repetitive nature of sequences. A typical sequence consists of cross-bedded eolian dunes eroded during a marine advance, and then overlain by marine dolostones, algal mats, and dolomitic marine sandstones. Subareally exposed marine units (exposure surfaces) suggest lowstand sequence boundaries. Overlying the marine units are dune and interdune sandstones. Tensleep sequence boundaries defined by log character can be correlated among other wells within the western Powder River Basin region.

AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah