The east-central states showed no consistent trend for permitting or drilling activity during 1987. All states in the district had a decline in oil production, with an average of 11.6% for the year.

In Illinois, the Geological Survey processed reports on 1,728 oil and gas tests, 878 of which listed 1987 completion dates. These included 432 exploratory tests and 1,296 development tests. Exploratory tests were 10.4% successful; development tests had a success rate of 63.7%. Total footage reported drilled was 3,578,268 ft; the average depth of a hole was 2,070 ft. Three new fields (2 gas, 1 oil) and 16 new pay zones in known fields were reported in 1987, as were 57 wells with initial production of 100 BOPD or more. The highest initial production was 760 BOPD from a well in Edwards County. Twenty-one tests were reported drilled to a depth of 4,500 ft or more. The deepest was a 6,000-ft well that tested the Devonian in Hamilton County. Drilling is expected to remain stable during 1988 Crude oil production is estimated at 24.1 million bbl in 1987, down 11.5% from 1986. Commercial natural gas production for 1987 is estimated at 1,377 mmcf. Six hundred and ninety-one wells were plugged, leaving Illinois with an estimated 32,426 wells producing oil and gas.

In Indiana, the increase in crude prices to an average of $17.29/bbl was not enough to alleviate the downward slide of production and drilling in the state. Oil production was 3.9 million bbl, the lowest since 1939. Drilling declined 32% in 1986 to 347 holes in 1987. Wells were 46.4% successful overall, development wells being 65.8% successful and exploratory holes having a success rate of 23.8%. Exploratory drilling discovered several noteworthy new pools, 1 oil field, and 3 gas fields. Two hundred and six wells were reported abandoned, leaving Indiana with an estimated 7,547 wells producing oil.

Drilling activity in Kentucky enjoyed a moderate rebound in 1987 with 2,700 wells reported completed and a success rate of 60%. The number of drilling permits for the year continued a decline to 1,838 from 2,413 in 1986. In addition, 727 permits were allowed to expire in 1987. Oil production declined 12% to 5,689,318 bbl. Total gas production in 1987 was 70.1 bcf, a 13% decline from 1986. In 1987, 700 exploratory wells were drilled, resulting in the discovery of 45 new fields and pools, 16 deeper pools, 9 shallower pools, and 153 extensions of existing pools. Total footage drilled during the year amounted to 3,917,175 ft, with an average well depth of 1,450 ft.

In Tennessee, permitting was up slightly with 256 permits issued during 1987. Well classifications dropped 44% in 1987, resulting in 301 completions with an overall success rate of 46%. Exploration resulted in 4 significant discoveries: 3 new fields and an extension. Oil production totaled 644,479 bbl, down 5% from 1986; gas production was 2.7 bcf, down 22%. Reclamation laws passed in 1987 went into effect in 1988.