The mid-eastern states are in the southern half of the northeastern United States and include Maryland, Ohio, Pennsylvania, Virginia, and West Virginia. Exploratory activity in this old petroleum province decreased significantly during 1986, as only 236 exploratory completions were reported, down 26.3% from 1985. Targets ranged from Triassic (in Pennsylvania and Virginia) to Cambrian (in Ohio and Pennsylvania). Overall drilling activity also decreased, as completions reported decreased 42.5%, and footage drilled decreased 41.7%. Drilling was relatively shallow but quite successful, with average well depths ranging from 2,806 ft in Pennsylvania to 5,316 ft in Virginia, and success rates ranging from 92.3% in West Virginia to 95.2% in Virginia. The big decline was in the nu ber of new oil wells, as oil plus combination completions decreased 52.5%, led by Ohio (down 53.4%) and Pennsylvania (down 55.4%). New gas well completions also decreased significantly (33.6%), due mainly to decreased activity in Ohio (down 51.9%) and West Virginia (down 39.6%). Gas production remained stable, with an increase in Pennsylvania offsetting declines in West Virginia and Maryland. Oil production, however, declined 12.8%, with all 4 oil-producing states registering a decrease.

For only the second time in the past 5 years, a well was drilled in Maryland. This exploratory well is located 3 mi southwest of Accident field, Garrett County. Total depth is 5,300 ft; other data are being held tight. Natural gas production in Maryland decreased 49.6% in 1986 from 1985. Seismic and leasing activity continued in the Mesozoic buried-basins play in the coastal plain of southern Maryland and the Eastern Shore.

Activity in Ohio decreased abruptly from record-setting 1985. Completions decreased 48.1%, and footage drilled decreased 52.1%. New completions were predominantly combination oil and gas wells (56.2%), mostly to the Lower Silurian "Clinton-Medina" sandstone. Exploratory activity decreased 35.1%, and only 3.2% of all completions were classified as exploratory. Exploratory targets ranged from Pennsylvanian to Cambrian, with high success rates (67.4%) in the "Clinton-Medina" and Berea, and lower success rates (20.6%) in the deeper Trenton-Rose Run and Cambrian units. The overall exploratory success rate was 52.0%. Oil production decreased 10.3% from 1985, but gas production declined only 0.09%. The decline in production, coupled with a decrease in the wellhead price of both oil and gas, esulted in a big drop in the dollar value of hydrocarbons produced in Ohio.

Reported drilling activity in Pennsylvania during 1986 decreased by 36.6%, and footage drilled decreased 22.2%. Exploratory activity also decreased, but the reported drilling was down only 6.4%, whereas footage drilled decreased 5.9% and seismic activity decreased 64.0%. Deep drilling decreased 24.6%; as in past years, deep drilling was concentrated on continued exploration and development of Lower Silurian Medina fields in northwestern Pennsylvania. Shallow drilling activity decreased 38.8% and was dominated by development of Upper Devonian Venango and Bradford oil and gas fields throughout western Pennsylvania. Significant exploratory tests were reported from northwestern, northcentral, and southeastern Pennsylvania, with targets ranging from the Triassic-Jurassic Newark Supergroup o the Lower Ordovician Beekmantown Formation. Oil production decreased 22.0%, and natural gas production increased 6.2%.

Drilling activity again increased in Virginia, as 147 new wells were drilled, up 54.7% from 1985. Total footage drilled also increased, by 53.9%. Exploratory activity increased 62.5%, and 7 of 13 wells were successfully completed for gas production in the Mississippian Ravencliff, Maxon, Big Lime, Weir, and Berea, and the Devonian shale. Exploratory failures included new-field wildcats in the Taylorsville Triassic rift basin, and deep tests to Silurian units. All but 1 of the successful development wells were completed for gas production in the stratigraphic interval ranging from the Big Lime to Devonian shale. The exception was an oil well in the Ordovician Trenton Limestone. Oil production decreased 31.2%, but gas production increased 2.6%, setting a new production record.

Drilling in West Virginia decreased 33.9%, and total footage drilled decreased 43.4%. Exploratory activity also decreased, with completions down 58.0% and footage

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down 42.8%. Seismic activity, however, increased 40.9%, and companies began conducting large-scale geochemical surveys. Exploration programs of interest included Oriskany tests in the Eastern Overthrust belt and adjacent high plateau folds, scattered Silurian tests, some Brallier siltstone tests, and deep Devonian shale wells in southern counties. Deep drilling decreased 20.3%; the success rate for deep drilling (35.6%) was far below the overall success rate for the state (92.3%). Although the number of new gas wells completed was the lowest since 1977, West Virginia is still a gas province. Production of gas, however, decreased 6.5%, and oil production decreased 10.7%.