SELECTED STUDIES OF CAMBRO-ORDOVICIAN SEDIMENTS WITHIN THE MICHIGAN BASIN Report of Investigation 26 D. Michael Bricker Randall L. Milstein C. Robert Reszka, Jr. Geological Survey Division Michigan Department of Natural Resources Lansing, Michigan 1983 ACKNOWLEDGEMENT The authors express their gratitude to Richard E. Weber, STATE OF MICHIGAN Conoco, Inc., Dr. James H. Fisher, Michigan State James J. Blanchard, Governor University and Robert C. Reed, Michigan Geological Survey for their critical review and useful suggestions in DEPARTMENT OF NATURAL RESOURCES the preparation of this report. We also wish to thank Ronald O. Skoog Dolores Bonner and Margaret Schineman for rough-draft Director and Supervisor of Wells and final typing of the manuscript, Donald Raymond for Geological Survey Division the execution of the report’s cover, and Gregory Wilson R. Thomas Segall for Word Processing. A very special thanks is extended State Geologist and Assistant Supervisor of Wells to Michial Jones for his part in the preparation of the plates and illustrations. NATURAL RESOURCES COMMISSION D. Michael Bricker Hoefer, Jacob A., Chairman Randall L. Milstein Anderson, Thomas J. C. Robert Reszka, Jr. Carollo, E. R. Monsma, Stephen V. Subsurface and Petroleum Geology Unit Snell, Hilary F. Geological Survey Division Wendler, Paul H. Whiteley, Harry H. Robertson, John M., Executive Assistant CONTENTS Published by Authority of State of Michigan compiled PART I laws of 1970 section 321.6 Maps, Cross-Sections and Lithology Randall L. Milstein..............................................................2 Copies of this and all other Department of Natural Resources Publications are available from: Introduction.....................................................................2 A Mood of Cautious Optimism .......................................2 Information Services Center Stratigraphy....................................................................4 Michigan Department of Natural Resources Box 30028 PART II Lansing, MI 48909 Description of the Prairie du Chien Group Through Microscopic Analysis of Samples On deposit in many libraries in Michigan and other C. Robert Reszka, Jr. ........................................................6 selected locations. Description of the Prairie Du Chien Group Through Microscopic Analysis of Samples...................................6 Report of Investigation 26 – Selected Studies of Cambro-Ordovician Sediments... – Page 1 of 11 PART III Hydrocarbon Production from the Prairie du Chien PART I Group Maps, Cross-Sections and Lithology D. Michael Bricker ............................................................. 8 Randall L. Milstein Introduction.................................................................... 8 Subsurface and Petroleum Geology Unit Production History ......................................................... 8 Michigan Geological Survey Division Figure 1. Location of wells which have produced 1983 hydrocarbons from the Prairie du Chien Group. ........... 8 Table 1. Well data summaries for wells which have INTRODUCTION produced hydrocarbons from the Prairie du Chien Group............................................................................. 8 At present, a considerable debate surrounds the definition of Cambrian and Ordovician formation tops as figure 2. Generalized stratigraphic correlation chart for they appear on geophysical well logs within Michigan’s Ordovician rocks in Michigan and nearby states........... 9 Southern Peninsula. This investigation has been Southern Michigan......................................................... 9 prepared as a means to help provide a more complete North Central Michigan.................................................. 9 picture of this stratigraphic sequence. Trapping Mechanisms ................................................... 9 In no way are the geologic cross-sections or text Figure 3. Stratigraphic section (southern Michigan) contained herein intended to be the definitive study on showing productive zones and dominant lithology in the Cambro-Ordovician sequence in Michigan. the Upper Prairie du Chien Group............................... 10 Hopefully though, they will act as a reference point from Figure 4. Stratigraphic section (north central which to expand and inspire more detailed studies and Michigan) showing productive zones and dominant establish a source of information from which other lithology in the Upper Prairie du Chien Group............. 10 government agencies, industry, educational institutions Conclusions ................................................................. 10 and private individuals can gain a more thorough data PART IV base from which to make future decisions concerning Oil and Gas Test Well Inventory: Prairie du Chien and the use of Michigan’s subsurface geology. Deeper During the preparation of this report, no attempt was C. Robert Rezka, Jr......................................................... 10 made to carry over outcrop terminology or to correlate List of Wells - Prairie du Chien and Deeper ................ 10 outcrop formations with subsurface units. Those formation tops selected are based solely upon data * * * * * * * * * * * derived from geophysical logs and sample reports. The Bibliography................................................................. 35 author has chosen as a foundation for his selections formation tops first ascertained by Garland D. Ells in 1967. The names used to identify these formations are It shall be the duty of the state geological survey those employed by the Michigan Geological Survey in to make or cause to be made, a thorough their investigations of Michigan’s subsurface. geological and mineralogical survey of the state, embracing a determination of the succession and arrangement, thickness, and position of all strata A MOOD OF CAUTIOUS OPTIMISM and rocks; their mineral character and contents, Since renewed interest in deep well drilling within the and their economical uses, ... The investigation of Michigan Basin began in 1980, and especially since the all deposits of brines, coal, marl, clay, gypsum, announcement of a gas discovery in the Dart Oil and lime, petroleum, and metals and metallic ores, Gas Corporation’s, Edwards #7-36 Deeper Pool Test, in building stone, marble, gritstone, materials for April of 1981, the majority of information requests dealt mortar and cement, mineral paint, and all other with by the Subsurface and Petroleum Geology Unit of productions of the geological world within the the Michigan Geological Survey have been concerned limits of this state capable of being converted to with the Cambro-Ordovician stratigraphic sequence. the uses of man. Though many wells have been drilled, and are currently --Act 65 of the public acts of 1869 being drilled to Cambrian and Ordovician horizons on the Basin’s periphery, prior to the early part of 1980, only eight oil and gas test wells had been drilled to these formations, roughly the 10,000 foot mark, throughout the Basin’s central region. For this reason an accurate data base was lacking from which to make reliable assumptions and decisions regarding the disposition of Cambro-Ordovician rock units. After the successful completion of the Edwards #7-36 well, an upsurge of deep well drilling has occurred in Report of Investigation 26 – Selected Studies of Cambro-Ordovician Sediments... – Page 2 of 11 Michigan’s Southern Peninsula. Most of the wells logs do not show all formations as distinct, individual log permitted are targeted for the upper regions of the signatures. However, certain curves and curve patterns Prairie du Chien Group. Fortunately, from a geologist’s are evident. These are correlatable and can be used as point of view, many of the wells continued to venture reliable, traceable log markers within the Southern deeper into what is relatively “unknown territory.” Peninsula. The gamma ray curve was used to construct the cross-sections because it shows the most With knowledge of these lower formations being at a consistently recognizable profiles. minimum and commercial interest in them at a maximum, when a well is drilled to these greater depths, In a given well, the lithologic description was compared sampling, coring and the running of extensive to its corresponding geophysical log suite. Individual log geophysical log suites have become a matter of suites were then correlated with others throughout the necessity. The information gained from these methods state by a combination of sample descriptions and has established a viable and, in most cases, accurate geophysical log characteristics. Contributing to the data base from which the Geological Survey, the difficulty in correlating these units is the often poor petroleum industry and other independent researchers quality of submitted sample descriptions. When a two can begin to draw some conclusions. thousand foot interval is described soley as “gray dolomite,” problems in accurate interpretation arise. For The Subsurface and Petroleum Geology Unit, in its these reasons the Prairie du Chien and Trempealeau dealing with the large number of inquiries concerning the formations have not been broken into their individual Cambro-Ordovician rock sequence, has found it quite components. The pattern for the correlation runs was evident that there is a difference of opinion concerning selected for convenience of presentation and to give formation identification and nomenclature. Garland D. what appears to be the most logical and complete Ells