For the 18th consecutive year, exploratory and development drilling for Middle Silurian Niagaran reefs dominated Michigan's oil and gas drilling activity. In 1986, 53% of the wells drilled had Niagaran objectives. The remaining drilling activity was spread among rocks from the Mississippian to the Precambrian throughout the Michigan basin.

Exploration resulted in 63 new discoveries, 73% of which were Niagaran reef reservoirs. While much attention was deservedly focused on the success of the deep Lower Ordovician gas play, many independent operators and a few major companies continued to make important new discoveries to extend the geographic limits and lifetime of the prolific northern and southern Niagaran reef trends. The short-term outlook is for continued exploration and development in these plays and in the shallow Devonian Antrim Shale gas of Otsego County, with drilling to other zones again severely curtailed.

Exploration and development footage was 1,496,033 ft exploratory and 1,220,013 ft development, compared with 2,346,021 ft exploratory and 1,676,686 ft development in 1985. An additional 71,916 ft was drilled in facility or service wells.

Gas sales rose again in 1986, whereas oil production declined. Preliminary figures show that Michigan produced 25,704,963 bbl of oil and 159,632 mmcf of gas in 1986.