3D Characterization of Manlove Field, a Cambrian Mt. Simon Gas Storage Field in Central Illinois

D. G. Morse and R. W. Miller
Illinois State Geological Survey, Champaign, IL

Manlove Field, a 150 BCF aquifer gas storage field in Champaign County, Illinois, consists of an anticlinal closure reservoir in the Cambrian Mt. Simon Sandstone with a sealing caprock formed by the overlying Cambrian Eau Claire Formation. The upper Mt. Simon is about 50’ thick and includes four sandstone facies- the rippled, the homogeneous, the bioturbated, and the deformed; a finely interlaminated dark gray shale and medium-fine sandstone facies; and rare thin beds of laminated dark gray shale facies. The various sandstone facies have low porosity (8–10%) and modest reservoir quality. The underlying main gas storage interval, where the sandstone has better porosity (12–15%) and less shale, consists primarily of cross-bedded, laterally discontinuous, channel facies. Thin shales occur locally and are interspersed among the reservoir sandstone strata. The sandstone is primarily cemented by silica.

Old Gamma Ray-Neutron and modern FDC-CNL logs, and core data were analyzed in order to prepare 3D models of Mount Simon V-shale and porosity. Because shale markers of the Mt. Simon could not be reliably correlated across the field or even between adjacent wells 1000’ apart, the models were constructed based on thicknesses below the top of the Mount Simon. Sandstone reservoir strata, as shown by several slice maps of the 3D distribution of porosity, include stacked channel sandstone bodies with locally continuous, bifurcating high porosity zones to 1 mile wide. Adjacent to these sandstone bodies are lower porosity zones with comparable size and similar north-south orientation, which are interpreted as abandoned channel fills. Other slice maps show a more heterogeneous, less organized sandbody geometries.

AAPG Search and Discovery Article #90900©2001 AAPG Eastern Section Meeting, Kalamazoo, Michigan