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The search for new reserves of oil and gas in Dakota and Lakota strata of the Powder River Basin is directed primarily towards stratigraphic-type traps. This study examines the relationships among producing channel-fill sandstones, clay plugs deposited in abandoned meander loops, and adjacent delta deposits in the Wyoming portion of the Powder River Basin.

Detailed analyses of the stratigraphy, depositional environments, and trapping mechanisms of ten important Dakota and Lakota stratigraphic-type oil and gas fields provide case histories that, by themselves, serve as widely applicable exploration models. The models that result from these representative reservoir studies are applied in an analysis of the Powell-Archibald area in the deeper part of the Powder River Basin.

Regional maps, included in the study, display shoreline trends, areas of concentration of sand deposits at the fronts of Dakota deltas, and the locations of major Dakota valley-fill channel sandstone systems. These maps, in combination with the depositional models detailed in the study, constitute a valuable predictive tool that can be used to guide future exploration efforts in the Powder River Basin.

The study area includes that part of the Powder River Basin lying south of Township 53 North, plus most of the Casper Arch, which separates the Powder River Basin from the Wind River Basin to the southwest. It encompasses a total area of 17,460 square miles, within which approximately 7,200 wells have penetrated the top of the Dakota.

Database

1600	Study Wells	76	Cores Described
9	Regional Stratographic Markers Correlated	200	Thinsections
46	Outcrops Measured

Maps

Regional Maps (1:2500000 (1:96000) (1:48000)		Facies Distribution Maps Field Maps (1:24000)
Interval Isopach Maps Net Sandstone Maps Structure Maps		Interval Isopach Maps Sandstone Maps Structure Maps

Cross Sections		Field Studies
8 Regional Stratigraphic Sections 12 Field Cross Sections		Burke Ranch, Donkey Creek, Lodgepole Creek, Lone Tree Creek, Sage Spring Creek, South Wood, Wood, West Moorcroft

Report Contents

TEXT AND FIGURES-An extensively illustrated report includes discussions, figures, and color plates on: Executive Summary, Depositional Setting, Lithofacies, Stratigraphy, Depositional History, Petrography, Field Studies, Synthesis, and Exploration Potential.	STRATIGRAPHIC DATA-These files contain the stratigraphic data (9 formation tops and stratigraphic markers, and net sandstone values) and isopach values, as well as information on well name, operator, location, API number, completion date, datum, and production status for the 1600 study wells.
CORES AND OUTCROP DESCRIPTIONS - This section contains descriptions of 76 cores from the study area. It also contains descriptions of 46 outcrop localities along the margins of the Powder River Basin.	MAPS AND CROSS SECTIONS - These sections contain the regional maps and field study maps. The maps include isopach maps, structure maps, and net sandstone maps. The cross sections include the regional and field cross sections.