For the 17th consecutive year, exploratory and development drilling for middle Silurian Niagaran reefs dominated Michigan's oil and gas drilling activity. In 1985, 61% of the wells drilled had Niagaran objectives. Ordovician Prairie du Chien Group targets were the next most popular objectives, accounting for 10% of the drilling. The remaining objectives were spread throughout Paleozoic rocks from the Mississippian to the Cambrian.

Exploration resulted in 69 new discoveries, 69% of which were Niagaran reef reservoirs. As the major oil companies drilling in Michigan turn their attention to Silurian "Clinton" and Ordovician Trenton-Black River and Prairie du Chien prospects, a rapidly growing number of independents are significantly extending the geographic limits and lifetime of the northern reef-trend exploration.

Exploration and development footage was 2,346,021 ft exploratory and 1,676,686 ft development, compared with 1,832,945 ft exploratory and 1,839,541 ft development in 1984. An additional 64,792 ft was drilled in facility or service wells.

Gas production rose in 1985, whereas oil production declined. Preliminary figures show that Michigan produced 29,140,000 bbl of oil and 152,840 mmcf of gas.