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The Evidence for Pinnicle Reef Growth in Kalamazoo and St. Joseph Counties, Michigan

J. E. Lentz
El Paso Energy, Detroit, MI

Oil and gas production from Niagaran aged pinnicle reefs in the Michigan basin has been prolific and well studied over the past four decades. Here, production has been from the reef itself where they are sealed by Salina aged evaporites. Less well known, but directly attributable to Niagaran reef growth is the Traverse Limestone oil production from the East Pullman pool in southwest Michigan’s Allegan County. The closure in this pool is a result of drape over a very tall reefal buildup. The Salina evaporites are not present here. A few other examples of reef induced closure (also Traverse reservoirs) are known in the Michigan basin at a handful of locations (also Traverse reservoirs) in the southern reef trend. In the Illinois basin all production related to Niagaran reef growth is found in reservoirs above the reef. The Salina evaporites are absent, but reef induced closure exists in the younger rocks.

Geochemical data, subsurface mapping and seismic data have been utilized to identify an area of reef growth similar to that found in the Illinois basin, or, like that at the East Pullman field location. That is to say, an area lacking reef sealing Salina evaporites, but with the reef inducing closure on younger formations, themselves being sealed. This area, centered on the Kalamazoo-St. Joseph County line, is sparsely explored and has been widely believed to be absent of pinnicle reef growth.

Compelling stratigraphic, seismic, and drilling evidence has been assembled which supports the postulation of pinnicle reef growth in this area.

AAPG Search and Discovery Article #90900©2001 AAPG Eastern Section Meeting, Kalamazoo, Michigan