Storms Consolidated field, Illinois basin: Identifying new reserves in a mature area

Discovered in 1939, Storms Consolidated field in the central Illinois basin has produced approximately 24.5 million bbl oil, mainly from Mississippian sandstone reservoirs, yet may contain significant remaining reserves. The field produces from a combination structural-stratigraphic trap along the u pthrown side of a major normal fault trend. Although the principal reservoi r zone, the Waltersburg Sandstone, is mostly depleted, another important in terval, the Aux Vases Sandstone, appears underexploited in many parts of th e field. Description and analysis of the: only continuous core through the Aux Vases has led to the identification of major lithofacies and their char acterization in terms of reservoir quality, The Aux Vases appears to repres ent a series of shallow marine bars separated by nonreservoir areas of silt stone, shale, and shaly sandstone. Log-based mapping of reservoir distribut ion, plus production and pressure data, indicates significant lateral and v ertical compartmentalization of the reservoir. Although insufficient data e xist for full-scale integrated reservoir characterization studies, a trend surface analysis was performed on structural information across the field. The results of this analysis were compared with reservoir distribution maps to identify areas for future drilling or recompletion.