U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2005–3070

June 2005

National Assessment of Oil and Gas Fact Sheet

Assessment of Undiscovered Oil and Gas Resources 

of the U.S. Portion of the Michigan Basin, 2004

Printed on recycled paper

Assessment Units

Nine of the AUs are characterized as conventional oil and gas accumulations, and four of the AUs are characterized as continuous accumulations. The 

nine conventional AUs are the (1) Precambrian Nonesuch AU; (2) Ordovician 

Sandstones and Carbonates AU, which includes the Prairie du Chien Group, St. 

Peter Sandstone, Glenwood Formation, and equivalent stratigraphic units within 

the basin; (3) Ordovician Trenton/Black River AU; (4) Silurian Burnt Bluff AU; 

(5) Silurian Niagara AU; (6) Silurian A-1 Carbonate AU; (7) Devonian Sylvania 

Sandstone AU; (8) Middle Devonian Carbonates AU, which includes the Detroit 

River Group, Dundee Limestone, and Traverse Group; and (9) Devonian to 

Mississippian Berea/Michigan Sandstones AU. All of these conventional AUs 

were assessed quantitatively, except for the Precambrian Nonesuch AU. 

The four continuous AUs are the (1) Ordovician Collingwood Shale Gas 

AU, (2) Devonian Antrim Continuous Oil AU, (3) Devonian Antrim Continuous Gas AU, and (4) Pennsylvanian Saginaw Coal Bed Gas AU. Of these four 

continuous AUs, only the Devonian Antrim Continuous Gas AU was assessed 

quantitatively.

Figure 1. Map showing the assessed area (U.S. portion) of the Michigan Basin 

(boundary in red).

By using a geology-based assessment methodology, the U.S. Geological Survey estimated the 

following quantities of undiscovered, technically 

recoverable oil and gas resources in the U.S. 

portion of the Michigan Basin: (1) a mean of 990 

million barrels of oil, (2) a mean of 11 trillion cubic 

feet of natural gas, and (3) a mean of 220 million 

barrels of natural gas liquids.

Introduction

The U.S. Geological Survey (USGS) has 

completed an assessment of the undiscovered 

oil and gas potential of the U.S. portion of the 

Michigan Basin (fig. 1). The assessed area 

includes the State of Michigan, as well as parts 

of Illinois, Indiana, Minnesota, Ohio, and Wisconsin. The assessment is based on the geologic 

elements of each total petroleum system (TPS) 

defined in the basin. These geologic elements 

include the hydrocarbon source rocks, reservoir rocks, and hydrocarbon traps. By using 

this geologic framework, the USGS defined 

6 total petroleum systems and 13 assessment 

units (AUs) within the basin and estimated the 

quantity of undiscovered technically recoverable 

oil and gas resources within 9 of the 13 AUs 

(table 1).

Total Petroleum Systems

The six total petroleum systems identified in 

the U.S. portion of the Michigan Basin are the 

(1) Precambrian Nonesuch TPS, (2) Ordovician 

Foster TPS, (3) Ordovician to Devonian Composite TPS, (4) Silurian Niagara/Salina TPS, (5) 

Devonian Antrim TPS, and (6) Pennsylvanian 

Saginaw TPS. Each TPS is named according to 

the petroleum source rock(s) of that system. For 

most of the systems, each TPS is associated with 

only one source rock. The Ordovician to Devonian Composite TPS, however, is a composite 

petroleum system having contributions from 

one or more of the following different source 

rocks: Ordovician Collingwood Shale, Devonian 

Detroit River Group, and the Devonian Antrim 

Shale.
Resource Summary

For the U.S. portion of the Michigan Basin, 

the USGS estimated the following quantities of 

undiscovered, technically recoverable oil and gas 

resources (table 1): 

(1) a mean of 990 million barrels of oil; 

(2) a mean of 11 trillion cubic feet of natural

gas; and 

(3) a mean of 220 million barrels of natural

gas liquids.

The Ordovician Trenton/Black River AU has 

the greatest potential for undiscovered oil, having an estimated mean of 723 million barrels of 

undiscovered, technically recoverable oil. The 

Devonian Antrim Continuous Gas AU has the 

greatest potential for undiscovered gas, having an estimated mean of 7 trillion cubic feet of 

Table 1. Michigan Basin oil and gas assessment results.

[All tabulated results are for technically recoverable resources. MMBO is million barrels of oil. BCFG is billion cubic feet of gas. MMBNGL is million barrels of natural gas liquids. 

Results shown are fully risked estimates. For gas fields, all liquids are included under the NGL (natural gas liquids) category. F95 represents a 95-percent chance of at least the 

amount tabulated. Other fractiles are defined similarly. TPS is total petroleum system. AU is assessment unit. Gray shade indicates not applicable or not assessed quantitatively]

undiscovered, technically recoverable gas. The Silurian Niagara AU, the 

Ordovician Sandstones and Carbonates AU, and the Ordovician Trenton/

Black River AU also have significant potential for undiscovered, technically 

recoverable gas.

Additional Information

Supporting geologic studies of the U.S. portion of the Michigan Basin 

total petroleum systems and assessment units are in progress. Assessment 

results, as well as information on the assessment methodology, are posted 

on the USGS Web site http://energy.cr.usgs.gov/oilgas/noga as they become 

available.

Michigan Basin Assessment Team

Christopher S. Swezey (Task Leader; cswezey@usgs.gov), Joseph R. 

Hatch, Daniel O. Hayba, John E. Repetski, Ronald R. Charpentier, Troy A. 

Cook, Timothy R. Klett, Richard M. Pollastro, and Christopher J. Schenk.

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