Illinois State Geological Survey
The Siluro-Devonian is one of the hottest oil and gas plays in the Illinois basin.
The play is centered in the basinward margin of the Mount Auburn trend along the southern flank of the Sangamon arch in central Illinois (Figs. 1 and 2).1 It consists of multiple geologically related prospects that comprise laterally discontinuous reservoirs in the Silurian Racine and Devonian Lingle formations at an average depth of 2,040 ft.
The Sangamon arch is defined by the zero thickness contour line of the Middle Devonian deposits. During Silurian time, a shelf margin was located about 70 miles southeast of the Mount Auburn trend faci...