Excellent three-dimensional exposures of
the Upper Jurassic Salt Wash Sandstone Member of the Morrison Formation
in the Henry Mountains area of southern Utah allow measurement of the thickness
and width of fluvial sandstone and shale bodies from extensive photomosaics.
The Salt Wash Sandstone Member is composed of fluvial channel fill, abandoned
channel fill, and overbank/flood-plain strata that were deposited on a
broad alluvial plain of low-sinuosity, sandy, braided streams flowing northeast.
A hierarchy of sandstone and shale bodies
in the Salt Wash Sandstone Member includes, in ascending order, trough
cross-bedding, fining-upward units/mudstone intraclast conglomerates, single-story
sandstone bodies/basal conglomerate, abandoned channel fill, multistory
sandstone bodies, and overbank/flood-plain heterolithic strata. Trough
cross-beds have an average width:thickness ratio (W:T) of 8.5:1 in the
lower interval of the Salt Wash Sandstone Member and 10.4:1 in the upper
interval. Fining-upward units are 0.5-3.0 m thick
©Copyright
1997. The American Association of Petroleum Geologists. All rights reserved.
1Manuscript
received March 25, 1996; revised manuscript received October 21, 1996;
final acceptance February 24, 1997.
2Snyder
Oil Corporation, 1625 Broadway, Suite 2200, Denver, Colorado 80202.
3U.S.
Geological Survey, MS 939, P.O. Box 25046, Federal Center, Denver, Colorado
80225-0046.
This
research was undertaken as part of a Ph.D. dissertation while J. W. Robinson
was at Colorado School of Mines and was a volunteer for the Branch of Petroleum
Geology at the U.S. Geological Survey. E. R. (Gus) Gustason at BP Exploration
(Alaska), Inc., first suggested the project and was an active participant
during many phases of the study. Simon Smith at KSEPL (Shell) helped construct
the reservoir and flow simulation models and was a gracious host while
J. W. Robinson was a visiting scientist at The Hague, Netherlands. We would
like to thank the following companies and organizations for their financial
and technical support of the project: BP Exploration (Alaska), Inc., BP
International, Ltd., Koninklijke/Shell Exploratie en Productie Laboratorium
(KSEPL), U.S. Geological Survey, Snyder Oil Corporation, Marathon Oil Company,
ARCO Exploration and Production Technology, Nuclear Assurance Corporation,
and the Department of Petroleum Engineering and the Department of Geology
and Geological Engineering at Colorado School of Mines. Keith Shanley,
Andrew Miall, and Michael Robinson provided helpful reviews of an earlier
version of the manuscript.
