--> ABSTRACT: Method for Evaluating Proximity to Niagaran Reefs of Michigan Basin, by Ronald J. Dehaas; #91041 (2010)

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Method for Evaluating Proximity to Niagaran Reefs of Michigan Basin

Ronald J. Dehaas

A simple but effective technique for evaluating the relative structural position of any exploratory Niagaran reef test is the "reefal structure section." This schematic section has the appearance of a cross section; however, geographic location does not determine the position of any individual test on the section. Instead, all holes in a local (approximately 2-mi2 area) are sorted strictly by subsea elevation of the Niagaran Brown unit. The reefal structure section is then generated with the highest Niagaran Brown unit on the right, progressing to the lowest Niagaran Brown unit on the left, all hung on a subsea datum.

Reefal structure sections clearly show the relative position of each test to the reef. Invariably, dry off-reef holes line up on the left side of the section, and productive (or dry on-reef) wells line up on the right side of the section. These sections are useful as an exploration tool in determining which holes in an area are near undiscovered reefs. They are also useful in the field, while drilling, as a predictive tool in projecting expected depths of formations.

When applied to a regional structural-stratigraphic framework, reefal structure sections are also useful in indicating which formations thin over reefs in different areas.

AAPG Search and Discovery Article #91041©1987 AAPG Eastern Section Meeting, Columbus, Ohio, October 7-10, 1987.