Oil production in Illinois, Indiana, Kentucky, and Tennessee in 1978 totaled 34,351,000 bbl, down 10.4% from 1977. Gas production in Kentucky was 70 Bcf, an increase of 15%; gas production in the other states is relatively insignificant. Oil and gas drilling tests numbered 2,909, down 1.8% from 1977. Exploratory tests totaled 1,034, down less than 1%; 210 (20.3%) were successful.

Tennessee had 222 oil and gas tests in 1978, down 9% from 1977. Exploratory wells (150) were down 3.8%; development wells (72) were down 19.3%. Success rate for exploratory wells was 40.0%, and for development wells, 73.6%. Although wells were drilled in 18 counties, Fentress, Morgan, and Scott Counties were the most active, accounting for 175 completions, including 47 exploratory wells. Total footage for all tests was 365,723, of which 108,194 was exploratory. Carbonate rocks of Mississippian age continued to be the most important targets of exploratory drilling. Most completions were made in the Fort Payne and Monteagle limestones. Enough additional gas was found in 1978 in Gruetli field to warrant construction of a pipeline. The gas is from the "Trenton" (Ordovician).

Illinois had 1,094 oil and gas tests in 1978, down 1% from 1977. Exploratory tests numbered 265, up 10%, and were 14.7% successful. Total footage drilled, including service wells and structure tests, was 3,084,666, down 1%. The highlight of 1978 activity was the discovery of Fort Payne (early Valmeyeran) production in New Harmony Consolidated field in White County. Through January 1979, 12 Fort Payne producers had been reported. Initial production figures ranged up to 600 BOPD and averaged 210 BOPD. Production is from broken porosity between 4,000 and 4,500 ft. Testing of the Salem Limestone and the immediately underlying Ullin Limestone (both Valmeyeran) accounted for 28% of the total tests in 1978. A total of 84 Salem producers was completed in 24 fields; 33 Ullin producers were com leted in 13 fields. The two formations accounted for more than 40% of the 1978 discoveries. Most of the Salem and Ullin activity is in a 9-county area with Wayne County at the center. Crude oil production in Illinois in 1978 was 23,362,000 bbl, down 8.8% from 1977.

Indiana had 669 oil and gas tests, up 10% from 1977. There were 268 exploratory tests, of which 14.9% were successful. Total exploratory footage was 531,760. Exploration and drilling activity remained principally in southern Knox County and northern Gibson County. At least half of the successful exploratory wells tested the St. Louis, Salem, or Harrodsburg Limestones. Of these, all but 4 resulted in completions in 1 or more of these stratigraphic units. The remaining 4 discovered oil in shallower pays. Exploration for St. Louis, Salem, and Harrodsburg reservoirs should spread to other fields producing from shallower pays in southwestern Indiana. Also, in large completely untested areas in southwestern Indiana, these deeper rock units should be considered to be promising targets for ex loration. Crude oil production in Indiana in 1978 was 4,684,000 bbl, down 11.9% from 1977.

In Kentucky 924 oil and gas tests were drilled in 1978, down 8.1% from 1977. The 351 exploratory tests, down from 365 in 1977, resulted in 38 oil wells and 33 gas wells, a success rate of 20.2%. Development wells were 63% successful, resulting in 256 oil wells and 105 gas wells. Exploratory interest in Valmeyeran production in western Kentucky waned in 1978, despite encouraging discoveries elsewhere in the Illinois basin. Seismic activity in eastern Kentucky was quite good, but deeper drilling declined despite large blocks of acreage held by the majors. Major discoveries in Cambrian-Ordovician strata in the Rome trough will be necessary to reverse a declining production trend. Crude oil production in Kentucky in 1978 was 5,712,339 bbl, down 13.19% from 1977.