Schaben Field, Kansas: Improving Performance in a Mississippian Shallow-Shelf Carbonate (E&P Notes)

©Copyright 2000. The American Association of Petroleum Geologists. All rights reserved.
¹Petroleum Consultant, 1511 18th Avenue East, Seattle, Washington 98112; e-mail: [email protected]
²Kansas Geological Survey, 1930 Constant Ave., Lawrence, Kansas 66047-3726.
Special thanks to the U.S. Department of Energy, National Petroleum Technology Office, Tulsa, Oklahoma; the Kansas Geological Survey; and Ritchie Exploration, Inc., Wichita, Kansas, the organizations responsible for this reservoir characterization study.

ABSTRACT

Schaben field (Kansas), located along the northeastern shelf of the Hugoton embayment, produces from Mississippian carbonates in erosional highs immediately beneath a regional unconformity. Production comes from depths of around 4400 ft (1342 m) in partially dolomitized shelf deposits. A detailed reservoir characterization/simulation study, recently performed as part of a Department of Energy Reservoir Class Oil Field Demonstration Project, has led to important revision in explanations for observed patterns of production. Cores recovered from three new data wells identify three main facies: spicule-rich wackestone-packstone, echinoderm wackestone/packstone/grainstone, and dolomitic mudstone-wackestone. Reservoir quality is highest in spicule-rich wackestone/packstones but is subject to a very high degree of vertical heterogeneity due to facies interbedding, silicification, and variable natural fracturing. The oil reservoir is underlain by an active aquifer, which helps maintain reservoir pressure but supports significant water production. Reservoir simulation, using public-domain, PC-based software, suggests that infill drilling is an efficient approach to enhanced recovery. Recent drilling directed by simulation results has shown considerable success in improving field production rates. Results from the Schaben field demonstration project are likely to have wide application for independent oil and exploration companies in western Kansas.