ABSTRACT: Depositional Compartmentalization of Heavy Oil in Mid-Continent Cherokee Group Fluvial-Dominated Deltaic Sandstones

JOHNSON, W. I., and D. K. OLSEN, IIT Research Institute/National Institute for Petroleum and Energy Research, Bartlesville, OK

Integrated geological and engineering analyses of Cherokee Group, Desmoinesian Series, Middle Pennsylvanian System sandstones, based on published and unpublished reports and theses, were conducted to evaluate the feasibility of recovering heavy oil in the Mid-Continent. Analyses for determining the successful and unsuccessful application of thermal enhanced oil recovery processes were performed on previous projects for both heavy and light oil reservoirs to determine their common characteristics. The primary difference between light and heavy oil reservoirs found in these areas, as shown by integrated reservoir analysis, is the gravity and viscosity of the oil.

Heavy oil reservoirs in the Mid-Continent are found in Paleozoic age carbonates and sandstones from Cambrian through Pennsylvanian Systems. Cherokee Group sandstone reservoirs in the Mid-Continent contain a large portion of these heavy oil resources. Mid-Continent Cherokee Group sandstones are dominated by those deposited as channel filling, multistoried, multistacked, discontinuous, fining-upward, multiple-point-bar fluvial-dominated deltaic sediments. These sandstones commonly have a lower facies that is more homogeneous and an upper facies that is more compartmentalized.

Ultimate recovery of oil from Cherokee Group sandstone reservoirs is affected by facies, small-scale sedimentary structures, bedding boundary and intergranular small-scale permeability barriers, and diagenetic changes, commonly noted as heterogeneities, within the sandstone body. Lower sandstone facies will have the largest volume of heavy oil that is recoverable by thermal processes. Upper sandstone facies will contribute small quantities of oil by thermal processes on a less cost-effective basis. Low recovery in upper sandstone facies is caused by depositional compartmentalization of the heavy oil resource.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)