The mid-eastern states are in the southern half of the northeastern United States and include Maryland, Ohio, Pennsylvania, Virginia, and West Virginia. Once again, drilling in this, the oldest petroleum province in the United States, was relatively shallow and quite successful. Mean well depths ranged from approximately 2,300 ft/well in Pennsylvania to 5,300 ft/well in Virginia, and success rates ranged from 94% in Ohio to 98% in Virginia. In Ohio and northwestern Pennsylvania, oil and gas drilling to Lower Silurian sandstones was of prime importance. Farther east, in Pennsylvania, West Virginia, and Virginia, the main targets ranged from middle Mississippian to Upper Devonian, and gas plays were the norm. Due to the great number of wells that have been drilled in this a ea (nearly 600,000 wells; 14,350,000 productive ac) most exploratory wells are either outposts or deeper pool tests. Scattered wildcats continue to be drilled, however, in the plateau portion of the basin, and deep wildcats to Lower Devonian Oriskany Sandstone or older targets were drilled in the Eastern Overthrust belt. Drilling activity, as measured by completions received by state agencies during 1985, increased in 3 of the 5 states, led by Pennsylvania and Ohio. Overall, activity increased 29.1% with 12,927 wells reported. This increase in activity was reflected in footage drilled in the region, up 24.3% from 1984. The number of new gas wells increased by 20.5% as both Ohio and Pennsylvania surpassed West Virginia in this statistic. However, the biggest increase in activity was in oi well drilling, as oil plus combination completions (again led by Ohio and Pennsylvania) were up 44.9%. Exploratory activity, however, failed to increase significantly. An increase in Pennsylvania was nearly offset by declines in Ohio and West Virginia. Thus, overall, the number of exploratory completions increased only 2.6%. Production of oil and gas failed to increase at all, as production of gas was down 2.5% and oil production declined 0.9%. Only Virginia showed a significant increase in gas production.

For the third time in the last 4 years, no wells were drilled in Maryland. Gas production from the state's 2 fields decreased 35% due to normal decline. Seismic activity and leasing of suspected buried Triassic basins continued in the coastal plain of southern Maryland.

Activity in Ohio reached a record high, surpassing that of 1983. Completions increased 24.7% from 1984, and footage drilled increased 28.4%. New completions were predominantly combination oil and gas wells (63.7%), mostly to the Silurian "Clinton-Medina" sandstone. Exploratory activity decreased 7.4%, and only 2.4% of all completions were classified as exploratory. These completions were dominated by Clinton-Medina tests with a high (81.5%) success rate. However, scattered deeper tests to the Ordovician Trenton Limestone and Rose Run Sandstone and various Cambrian formations resulted in only 4 successes in 41 attempts. Shallow exploration was most successful in the Devonian Ohio Shale and Mississippian Berea Sandstone. Oil production decreased 1.9%, and gas production decreased 2.3%.

Drilling activity in Pennsylvania during 1985 increased by 79.3%, and footage drilled increased 70.7%. Exploratory activity also increased, as completions were up 27.9%, footage increased 30.0%, and seismic activity increased 32.6%. The exploratory success rate dropped from 1984, but was still excellent at 76.6%. Deep drilling increased 70.1% and again was concentrated on extending and developing Lower Silurian Medina fields in northwestern counties. Shallow drilling increased 75.5% and was dominated by continued extension and development of Upper Devonian Venango and Bradford oil and gas fields. Farther east, deep exploration programs included scattered tests of the Lower Devonian to Upper Silurian carbonates, and Lower Ordovician to Middle Cambrian formations. Oil production increas d less than 1%, and gas production decreased 9.5%.

Virginia had another increase in drilling activity (39.7%) and footage drilled (48.3%). Exploratory activity remained fairly stable with a decrease of 1 well from 1984. This drilling was successful, however, with 6 of 8 wells producing gas in the Mississippian Big Lime, Weir, Price, and Berea, and the Devonian shale. All of the new development wells were completed in this same stratigraphic interval, and all produced gas. Gas production increased 78.5%, reaching a record high. Oil production, however, decreased 22.7%.

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Drilling in West Virginia decreased 10.1%, and total footage decreased 26.5%. Exploratory activity also decreased, with completions down 6.0%, footage down 21.0%, and seismic activity down 72.5%. Exploration programs of interest included deep Oriskany tests on major structural features in eastern counties, Tuscarora tests in several southern counties, and continued drilling to Upper Devonian shales, siltstones, and sandstones in northern West Virginia. Deep drilling decreased 16.9%, and the success rate (44.6%) was far below the state's average (96.1%). Although the number of new gas well completions decreased from 1984, the state is still predominantly a gas province. Production of gas, however, increased only 1.0%, and oil production increased only 1.4%.