Reservoir heterogeneity and improved oil recovery of the Aux Vases (Mississippian) Formation at King Field, Jefferson County, Illinois

The Aux Vases Formation at King Field averages 50 feet thick. Porous and permeable reservoir sandstones are rarely thicker than 20 feet and are typically lenticular. Clean, porous sandstone may, within one well location (660 ft), laterally grade into siltstone, nonporous calcareous sandstone, shale, or limestone. The Aux Vases Formation was deposited in a mixed carbonate-siliciclastic, nearshore, shallow marine environment. The carbonate lithology commonly is not productive and has low permeability; therefore, it is interpreted to be a barrier to fluid flow. The original drive mechanism at King Field was solution gas. There is no consistent oil/water contact in this field because of the heterogeneous nature of the reservoir sands. An improved oil recovery infill drilling program combined with selective waterflooding may be able to recover most of the remaining primary reserves. The data in this report will facilitate the implementation of enhanced oil recovery techniques. -from Author