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The sandstones of the Desmoinesian Cherokee Group in western Kansas are important hydrocarbon producers. The Start oil field in Rush and Ness Counties is an example of an unconformity-related Cherokee accumulation from which an exploration model can be made. In this field, the upper Cherokee member is economically important and is interpreted to be a marine unit deposited on the distal portion of an alluvial plain. Traps and reservoirs in this unit were formed by winnowing of clay and silt-sized material from sediments deposited on the crests of paleohighs.
Four maps are useful in exploring for upper Cherokee hydrocarbon accumulations such as Start. An isopach map of the Cherokee Group is useful for locating thins that coincide with paleohighs on the basal Pennsylvanian unconformity. An isopach map from the Cherokee top down to the first sandstone porosity is useful. "Thins" of this interval define areas where wave and current action have winnowed finer material from sands. Closed anticlines on a Cherokee structure map are areas where Cherokee reservoirs are likely to be oil bearing rather than water bearing. An isopach map from the Cimarronian Stone Corral anhydrite top down to the Missourian Lansing Group top is also useful. "Thins" of this interval correspond to paleohighs on the basal Pennsylvanian unconformity. This interval can be icked from seismic records. Prospective areas occur where isopach thins of Stone Corral to Lansing, of Cherokee Group, and of Cherokee top to first sandstone porosity coincide with Cherokee anticlinal structure.
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