Drilling for Devonian Antrim Shale targets surpassed the search for Middle Silurian Niagaran reefs, which had dominated Michigan's drilling scene for the past 19 years. In 1988, 36% of the wells drilled in Michigan had Antrim Shale objectives. Remaining drilling activity was spread among rocks ranging from the Mississippian through the Precambrian throughout the Michigan basin.

Exploration resulted in 40 discoveries, 58% of which were Niagaran reef reservoirs. Another 25% of the discoveries was in the still emerging Lower Ordovician deep play; an additional 13% of the discoveries was attributed to the shallow gas play in the Antrim Shale.

Drilled footage amounted to 1,023,471 ft exploratory and 1,080,978 ft development, compared with 1,218,472 ft exploratory and 898,575 ft development in 1987. An additional 60,902 ft was drilled in facility or service wells.

Gas sales increased slightly in 1988, but oil production declined. Preliminary figures show that Michigan produced 23,713,160 bbl of oil and 151,809 mmcf of gas in 1988.