During late Mississippian time a series of major regional movements took place resulting in two pronounced subsurface features that we now refer to as the Central Kansas Uplift and Nemaha Ridge. Subsequent post-Mississippian

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erosion gives us the present day configuration of Osagian rocks, subcropping beneath Pennsylvanian sediments.

A facies change in Mississippian rocks of south central Kansas, known as the "Cowley", makes definition of the Osage-Meramec contact difficult. The Osagian series consists of the Keokuk and Burlington cherty limestones. These rocks produce gas and/or oil in fifteen central Kansas counties. There are twelve major Mississippian Osage pools in this area. The largest oil and gas fields have estimated ultimate recoveries of 60 million barrels of oil and 450 billion cubic feet of gas respectively.

The Osage produces from stratigraphic and/or structural traps. Areas that are more suitable for a specific type of entrapment can be regionally defined. Problems of reservoir development exist near the truncation of basal Osage reservoirs.

In the past ten years Osage reservoirs have yielded approximately 75% of its total oil and gas production. Exploration concepts gained in this aggressive period assures the future of Osage rocks in Kansas as a principal producing horizon.

ROBERT M. EUWER

Robert M. Euwer graduated from Louisiana State University in 1951 where he received a B.S. degree in Petroleum Geology.

He was with Shell Oil Company for ten years as an exploration geologist with assignments in Texas, Oklahoma and Kansas. For the past two and one-half years he has been geologist for Kenneth Rupp, Independent Oil Producer, Wichita, Kansas.

He is a member of the American Association of Petroleum Geologists and the Kansas Geological Society and is currently on the Board of Directors of the Kansas Geological Society.

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