Manistique Group Reservoirs in the Michigan Basin: an Overlooked Resource

Abstract

In order to fill in the gap between the extensive studies of the overlying Niagara Group and underlying Burnt Bluff Group, initial work has been done to constrain the timing and nature of deposition of the Manistique Group. Manistique Group carbonates in the Michigan Basin include the nodular dolomites of the Schoolcraft Formation and cherty carbonates of the Cordell Formation. Several completions in the Manistique Group have been attempted, but currently there is no production. Reservoir characteristics include: 1.) small pods of dolomite within the regional limestone, 2.) association with structures and related fracture porosity, 3.) enhancement of porosity through generation of intercrystalline and vuggy porosity by dolomitizing fluids, and 4.) presence of porous, tripolitic cherts.

Carbon isotope chemostratigraphy shows that the Gray Niagaran hosts the Ireviken excursion (Sheinwoodian) above the contact with the Cordell Formation. Conodonts sampled from the Gray Niagara in the interval that records the Ireviken excursion are Sheinwoodian in age and include Kockelella walliseri, K. ranuliformis, and Ozarkodina sagitta rhenana. Above the contact of the Gray Niagara with the Cordell Formation, elements of Pterospathodus amorphognathoides were found, which constrains the earliest Niagara Group to uppermost Telychian in age. Previous work (Kuglitsch, 2000), found that the uppermost Burnt Bluff Group was early Telychian in age. These new data points constrain the age of the Manistique Group to the Telychian.

The Manistique Group carbonates exhibit elevated gamma ray signatures compared to the underlying Burnt Bluff Group and overlying lower Niagara Group. Handheld XRF data from the Miller Brothers Weinert #2-6 provided compositional data that shows that the Manistique Group is composed of a mix of argillaceous carbonates and cherts. The presence of chert, extensive bioturabation, and a low diversity fauna suggest that these carbonates were deposited in deeper water, likely above storm wave base.

Integration of biostratigraphic and geochemical data has enhanced our understanding of the deposition of the Manistique Group carbonates and has provided constraints on the nature of diagenetic overprints and reservoir development in these fields.

AAPG Datapages/Search and Discovery Article #90258 © 2016 AAPG Eastern Section Meeting, Lexington, Kentucky, September 25-27, 2016