The Dow Chemical Company's interest in oil shale was directed in the 1950's toward in situ processes and local shales, specifically the Antrim, a black Devonian shale which occasionally produces natural gas and which yields produces natural gas and which yields 9–10 gallons of oil per ton when retorted. It underlies most of the lower peninsula of Michigan.
Various field studies by Dow of the Antrim shale have resulted in the drilling of some 21 wells and the cutting of over 5000 feet of core. Dow researchers have retorted Antrim shale in laboratories and in surface retorts and underground combustion experiments have been conducted in a quarry and through bore holes at depths of 1200' and 2600' below the surface. Both high pressure air and oxygen have been used underground as reactants. Hydraulic fracturing and chemical explosives have been used on a massive scale in attempts to generate the necessary fracture permeability for in situ retorting. The costs have been large and the technological problems yet to be solved are formidable, however the potential of the eastern oil shale is so large that a continuing effort has been recommended to the Federal Government.
As early as June, 1955, research planners for The Dow Chemical Company were suggesting that underground processes, including in situ retorting, be studied with specific attention to the essential problem of rubblizing the strata, because the long range availability of energy and organic raw materials was not favorable at some Dow plant sites. A block of Colorado oil plant sites. A block of Colorado oil shale was purchased, however, interest soon shifted to a local oil shale a little more than half a mile below our power plants at Midland, Michigan. This shale, plants at Midland, Michigan. This shale, the Antrim of Michigan, is a Chattanooga-type shale that represents only a small part of the very extensive oil shale deposits of Devonian age in the Eastern and Mid-eastern parts of the United States (Figure 1). parts of the United States (Figure 1). The U.S. Geological Survey estimates that these shales underlie an area of over 400,000 square miles.