In Tennessee, 316 oil and gas tests were reported in 1981, down 11% from 1980. Exploratory tests (188) were down 4.2%, and development tests were down 21.1%. In 1981, 1,228 oil and gas permits were issued, up 32.5% from 1980. Total footage drilled for the wells reported was 529,034 ft. Carbonates of Mississippian age continued to be the most important exploratory objectives. In Hancock County, a Cambrian test to a proposed depth of 17,000 ft was spudded in December. A proposed 10,500-ft test to the Precambrian is being drilled in Anderson County. Leasing was very active in 1981. Crude oil production in 1981 was 917,524 bbl, up 23.5%. Marketed natural gas was 1,718,915 mcf, up 37.7%. Nearly all of Tennessee's oil and gas production is from stratigraphic traps in the Fort P yne (Lower Mississippian) and Monteagle (Upper Mississippian) limestones.

Illinois reported 3,140 exploratory and development oil and gas tests in 1981, up 58.4% from 1980. Exploratory tests numbered 665, up 47.5%. Total footage drilled, including service wells and structure tests, was 8,803,668 ft, up 61.6%. The Salem Limestone and to a lesser extent the immediately underlying Ullin Limestone (both Valmeyeran) continue to be important drilling objectives. In 1981, Salem production was discovered in 10 fields and Ullin production in 5, all deeper pool discoveries. A total of 318 Salem wells, including 61 multiple pay producers, was reported in 45 fields in 1981. Including only holes of 4,000 ft or deeper, 16 new-field and 21 new-pool exploratory wells tested the Devonian or deeper. At total depth, 1 of these tested the St. Peter, 5 tested the "Trenton," and 31 tested Devonian-Silurian rocks. Only 2 of the wells--both Devonian deeper pool discoveries--were exploratory successes. The deepest well reported in 1981 was a 6,105-ft "Trenton" test in Franklin County. It was completed as a deeper pay discovery in the Devonian. Crude oil production in 1981 was 25,490,000 bbl, up 10.2% from 1980.

Indiana reported 811 oil and gas tests in 1981, an increase of 11.9% over 1980; 348 exploratory tests were drilled (up 8.1% from 1980), with a success rate of 20.1%. Drilling for oil in a sandstone of the Renault Formation (Mississippian), spurred by successes in Posey County in 1980, resulted in 7 exploratory successes in the Renault sandstone in Posey and Gibson Counties in 1981. In Miami County, northern Indiana, in an area of the Peru field that data suggested was untested, a successful Trenton Limestone well was completed in 1981. The field was discovered in 1895. Testing and leasing in the main area of the old Trenton field in east-central Indiana continued in 1981. Estimated crude oil production in Indiana in 1981 was 4,730,000 bbl, down about 248,000 bbl from 1980.

In Kentucky, 5,364 permits were issued in 1981, an increase of 29.8% over 1980. The number of oil and gas tests completed was 1,679, an increase of 35%. Of these, 852 were producers, an increase of 47%. Of the 486 exploratory wells drilled, 124 were successful, a success rate of 25.5%. Discoveries included 3 oil fields, 4 gas fields, 15 deeper oil pools, 1 deeper gas pool, and 1 deeper combination oil and gas pool. Continued interest in deep Cambro-Ordovician strata in the Rome trough throughout central and eastern Kentucky, heightened by some successes, should ultimately lead to the discovery of sizable reserves. Estimated oil production in 1981 was 6,540,484 bbl, an increase of 10%. Gas production was 61.3 bcf, an increase of 5.2%.