Regional Depositional Control on Dundee Reservoirs in the Michigan Basin

T. R. Maness
Maness Petroleum Corporation, Mount Pleasant, Michigan

The Devonian Dundee Formation in the Michigan Basin contains several distinct reservoir modes. Porosity types range from primary limestone to secondary dolostone in normal marine to restricted depositional environments. Depositional facies have a north-south strike and thus reservoir types are partitioned east to west across the central basin.

While the top of the Dundee is readily correlated over much of the basin, the base is less definite. Most workers pick the base at the first (uppermost) anhydrite bed in the Detroit River Group. However, the first anhydrite bed at one locale may not correlate with the first anhydrite bed at another, confounding interpretation. Stratigraphically lower marker beds can be correlated and help unravel lower Dundee/upper Detroit River depositional relationships. Dolomitization is key for some of the reservoir types. Geologists have long debated different mechanisms for dolomitization in general and the Dundee in specific offers ample opportunity to discuss competing models. The process of hydrothermal fluids percolating through localized faults and fractures is often invoked to explain dolomitization of the Dundee’s Roger City Member, but a regional perspective suggests that alternative models better fit the distribution of dolostone.

Recently, Dundee reservoirs have been the focus of efforts to exploit bypassed oil. The potential for significant remaining recoverable reserves has been largely overstated, particularly in dolomitized Rogers City Member reservoirs. Field studies indicate that 60–70% of the original oil in place has been recovered in most of the pools. These water-drive reservoirs had very efficient recoveries despite the lack of modern production practices.

Still, the Dundee offers opportunity for explorationists. Careful study of existing fields may result in profitable infill drilling and solution- gas reservoirs have potential for secondary and tertiary recovery. New fields remain to be found with improved technology and a commitment to drill.

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