Total oil production in Indiana, Illinois, Kentucky, and Tennessee during 1971 was 56.9 million bbl, down 9.8% from 1970. Only Tennessee showed an increase in production, from 309,305 bbl in 1970 to 398,424 bbl in 1971. Gas production in Kentucky was 72.7 Bcf in 1971, down 4.3%, although there was a slight increase in western Kentucky. Gas production in the other 3 states is insignificant.

The total number of oil and gas tests drilled was 1,713, down 8.2%. Only Tennessee had an increase in drilling, 171 tests in 1971 compared with 74 in 1970. Exploratory tests totaled 595, a decrease of 2.9%. Of these, 106 (17.8%) were successful. They did not add significantly to reserves. Kentucky led in the number of both exploratory and total wells.

In a relatively untested area along the western edge of the structurally deformed Valley and Ridge province in Tennessee, 2 Silurian tests in Rhea County encountered a massive section of Mississippian carbonates and slight shows in several zones; a 3,125-ft test in southeastern Morgan County was drilled below the Chattanooga Shale. Details of that well have not been released.

Much of the wildcat drilling in Illinois in 1971 was at the extreme southern edge of production (in the area of the Cottage Grove-Rough Creek fault system), and on the Illinois basin platform in southwestern Illinois and the Christian and Sangamon Counties area. The target on the platform is Silurian reef production. Although only one well reported in the faulted area in 1971 reached as deep as the Devonian, the geologic knowledge being accumulated is expected to lead to deep testing in the area in 1972. Several deep tests in other parts of the state are also expected in 1972.

In Daviess, Greene, and Knox Counties, Indiana, 48 exploratory tests in 1971 resulted in 8 exploratory successes. Although not generating substantial reserves, these successes are significant because they are in an area not so densely drilled as the counties in the deeper part of the Illinois basin, and they should provide impetus for continued exploration in these counties and counties contiguous on the east and south.

The only deep drilling in the east-central states was in Kentucky. In Morgan County a new-field wildcat was drilled to 10,017 ft in the Precambrian and completed as an oil well in the Knox at 4,794 ft. A test in Lawrence County was drilled to a total depth of 12,706 ft (tops not available), and a 12,740-ft basement test was drilled in Pike County (logs not released).