Although the Illinois Basin is a relatively mature reservoir, abundant opportunities exist for primary and enhanced recovery methods. The Basin covers 59,000 square miles in the tri-state area of Indiana, Illinois, and Kentucky and contains coveted high gravity, low sulfur oil.

The average pay zones range from 1000 feet to approximately 5000 feet deep with an average depth of 2400 feet. Deeper zones such as the St. Louis, Salem, Warsaw, and Devonian are showing extensive promise. Although secondary recovery or pressure maintenance has nearly tripled the amount of recoverable oil in the Basin, estimates calculate that nearly two-thirds of the petroleum reservoirs still remain below the surface.