Mississippian Osage, Northwest Oklahoma Platform: ABSTRACT

Abstract

The Sooner trend portion of the Northwest Oklahoma platform comprises a fractured limestone belt sub-paralleling the Anadarko basin hinge-line from West Edmond field through Enid townsite to Ringwood field. It ranges in width from 15-30 mi. and it is approximately 90 mi. long. Fracturing forces have been supplied by orogenies affecting the Nemaha ridge and Anadarko basin. Open fractures within the brittle cherty members of the thick Mississippian carbonate possess permeability ranging from sub-commercial to astronomically high. The reservoirs exist because of this widespread, effective permeability system. High initial potentials and fairly wide regional drainage support the common-source concept. Fracture density often determines reservoir value. It is difficult to predict fracture density in advance of drilling. Consequently, attractive areas are defined by End_Page 1562------------------------------ local drilling and by close observation of individual well productivity. Primary porosity is generally absent. Whole-core analysis reveals a fracture porosity average of 2% or less and an average net effective productive interval thickness range of 50-400 ft. Reserves are limited and estimates differ in direct proportion to the fracture density, gas/oil ratios, initial potentials, and total number of producing wells in an area. Commercial production can be obtained if the available facts are evaluated properly. End_of_Article - Last_Page 1563------------