Niagaran reef exploration continued to dominate drilling activity for the ninth straight year. Exploration was heaviest in northern counties along the reef trend. Other pockets of activity were apparent in southeastern Michigan and in the Ingham-Calhoun-Eaton County region. Exploration in these parts of the basin was mainly for Niagaran reefs.

Exploration resulted in 71 new discoveries, nearly all of which were Salina-Niagaran reef reservoirs. About 80% of the new discoveries were directly associated with the northern reef trend. Four new reefs in Presque Isle County indicate future developments in the coming year.

Exploratory and development footage, figured from records of the Michigan Department of Natural Resources Geological Survey Division, amounted to 2,519,809 compared with 2,349,191 drilled in 1976. An additional 89,637 ft, mainly gas storage facility wells, is credited to 1977.

Oil and gas production continues to set new records as additional reef reservoirs are found. Preliminary figures show that 32,964,503 bbl of oil (including condensate) and 133,215,209 Mcf of gas were produced in 1977. Both figures are new records and are direct results of Silurian Salina-Niagaran reef developments.