--> Abstract: Evidence for Vertical Petroleum Leakage Across Silurian Evaporites in the Michigan Basin of North America, by J. R. Hatch, C. S. Swezey, D. O. Hayba, W. B. Harrison, A. S. Wylie, J. E. Repetski, J. A. East, and A. Modroo; #90039 (2005)

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Evidence for Vertical Petroleum Leakage Across Silurian Evaporites in the Michigan Basin of North America

J. R. Hatch1, C. S. Swezey2, D. O. Hayba2, W. B. Harrison3, A. S. Wylie4, J. E. Repetski5, J. A. East2, and A. Modroo6
1 U. S. Geological Survey, Lakewood, CO
2 U. S. Geological Survey, Reston, VA
3 Western Michigan University, Kalamazoo, MI
4 Michigan Technological University, Houghton, MI
5 U.S. Geological Survey, Reston, VA
6 M&M Exploration Partners, Traverse City,

The Michigan Basin is an intracratonic basin with >4,800 m of Paleozoic strata containing abundant oil and gas resources. Within this basin, thick and laterally extensive Silurian evaporites (Salina Group) are generally thought to inhibit the vertical migration of hydrocarbons. However, there are several lines of evidence for petroleum leakage across the Silurian evaporites. Evidence for leakage includes the presence of geochemically mixed oils containing the hydrocarbon signature of Gloeocapsamorpha prisca (an organic-walled microfossil of Cambrian and Ordovician age) in Devonian carbonate reservoirs overlying the evaporite interval in the central part of the basin. In addition, many of the oil reservoirs in the central part of the basin (both above and below the Salina evaporites) are located along NW-trending fractures that appear to be controlled by reactivated deep basement faults. Recent interpretations of seismic data suggest that these fractures form flower structures that have experienced left-lateral strike-slip movement. In Ordovician and Devonian carbonate reservoirs, some of these fractures are associated with minerals that are typical of hydrothermal fluid flow (e.g., saddle dolomite, barite, fluorite, galena, and sphalerite). These features suggest that oils from Ordovician source rocks may have migrated into Devonian reservoirs during an episode of hydrothermal fluid flow, probably associated with the Late Devonian-Mississippian Acadian orogeny and (or) the Pennsylvanian-Permian Alleghanian orogeny.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005