Reservoir Characterization of the Middle Pennsylvanian Cleveland Sandstone, Cleveland Field Unit, Pawnee County, Oklahoma

Abstract

The Cleveland Field Unit has produced an estimated 50 MMBO since its discovery in 1904. Wireline data from old oil fields is sparse and has a resolution much lower than that of modern conventional wireline logs. Consequently, oil-in-place calculations commonly are underestimated. By use of data from cores, borehole-image logs, and modern well-logs, in-place oil and gas volumes can be estimated more accurately.The purpose of this study was to re-evaluate a mature oil and gas field by use of high-resolution reservoir data in a manner that estimates oil and gas volumes and accurately identifies bypassed "pay". This thesis presents data obtained from the Middle Pennsylvanian (Desmoinesian) Cleveland Sandstone in what is now the Cleveland Field Unit. The Cleveland Sandstone is composed of four distinct depositional units, and these units range in thickness from 5 ft. to 100 ft. Oil-and-gas-bearing zones, commonly interstratified with siltstone and shale, have been discounted because the values recorded by vintage wireline logs led to an under-calculation of in-place oil volumes due to the low resolution of those wireline tools (gamma-ray, induction, and micro-log). This study is thought to have potential application in other mature oil and gas fields producing from fluvial/deltaic depositional systems in the Mid-Continent.