LIIT'L^"EL ITP Jed R. Maebius y E a . ; :s" . ! . :_; , =: "A 4. _ t ._. _.. , .f L, F .d f ^ ; Ij: r . _ .a1'.: _..-,{, ; , f - win. PKOIliTy OF , _. F . - ,' ". _ .. f,- y 1817 4-,' i 2W . I!- J : *A l '1 VE TAR r : r. ' 1 ., V K. -Thy 'v , -' 4 t *-'~~'~'t~V + .:.-- ,3s Mai ,> _ ,_"3 ' ,_ -411 '7~ i.~4j '2> -~ , 2 R' . _ a2 , < .. i T~xE PORTER OIL F IELD by l~ed B-. Maebiua Department of Geology University of Miohigan ray, 1935 i TABLE OF CONTENTS INTRODUCTION Location and Extent of the Area. 1 Events Leading to the Discovery of Oil 1 Source of Geologic Data 2 Acknowledgements 3 STRATIGRAPHY Early Paleozoic Rocks 3 Devonian System 4 Mississippian System 7 Pennsylvanian System 9 Permo-Carbonif erous(?) System 10 STRUCTURE Regional Structure 14 Local Structure 15 Porter Oil Field Structure 15 Major Trend, Size, and Relief 15 Minor Variations 17 Thinning and Thickening of Formations 18 Unconformities 18 Origin of the Structure 20 Theory of Differential Compaction 20 Solution Theory 21 Theory of Norizontal Compression 21. Movements in the pre-Cambrian Rocks 22 U Production 24 Acid Treatment 24 Properties of~ the Oil 26 Future of the-Field 26 " i LIST OF FIGURES Tab le I 11, 12, 13 Figure I 16' Figure II 23 Figure III 25 iv PLA'TES PLATE I Subsurf'ace Structural Contours Lower Marshall rormation PLATE II Subsurface Btruc tural1 Uontours Traverse Yormat i on PLATE III Subsurf ace struc tural1 Uontours Dundee Formation PLATE IV Section A-A Across Porter Oil field THE PORTER OIL FIELD INTRODUCTION Location and Extent of the Area The Porter oil field is located in Porter township:, Midland County and extends in a northwest direction aeros Porter township and into the northeast corner of Jasper town- ship and the southeast corner of Greendale township. The extension of the pool four miles to the northwest ih Jasper and Greendale townships is called the lost field. Six miles farther along the same trend to the northwest lies the Green- dale field. The Porter oil field has an estimated produing area of 3000 acres, but inasmuch as the structure has not yet been completely defined, the potential acreage will be increased with future drilling. Eents Leading to the Discovery of Oil On November 14, 1931, the Michigan Facific 01 and Gas Company brought in an oil well on the James hi. Otway, ir., lease in tnre W*, W4jN,LW' of oeetion 26. This location is on the extreme southeast of the proven field. The well made ll1 barrels at a depth of 3417 feet, the oil coming from the vundee formation. In December, 1932, the Pure Oil Company brought in the Mattie Yost No. I in 51, Wi, t1* of Section 35, Greendale 2. township. This well is about five miles northwest from the discovery well in what is now called the Yost field. The initial production of this well was 1155 barrels. It was after the discovery of this well that a structure of consider- able extent was indicated. On February 27, 1933, the Michigan Pacific Oil and Gas Company brought in the J. H. Otway well in the *So* NE.t SW.A sec. 22. This well made an initial production of 300 barrels and after drilling 35 feet deeper and treating the well with acid, it made 3200 barrels in 36 hours. The discovery of this well was the beginning of intensive drilling operati ons in the surrounding region, especially in section 22. The logs from th6lbriftetellesof the- Dow Chemical Company, located in a line along the boundary between Jasper and Porter townships, were also used in working out the structure. Source of Geoloc Data The logs of the oil wells,which serve as the principle basis of this report, were obtained from the Oonserva- tion Department of the Eichigan Geological Survey, Lansing, Michigan. Well samples were obtained from the Pure Oil Company, Saginaw, Michigan. These samples were used in describing the formations, and also in determining by chemical analysis that the pay horizon was dolomitic. 3. Acknowledgments Many helpful suggestions for the preparation of this paper were furnished by the staff of the Department- of Geology, University of Michigan. Dr. R. B.. Newcombe, George Lindberg, and F. R. F'ye of the Michigan Geological Survey were very generous in giving helpful suggestions and making available the materials necessary for the work. W. A. Thomas of the Pure Oil Company furnished well samples and information that was necessary in working out the stratigraphy of the area. STRATIGRAPHI Early PaleozotieRocks The sedimentary rock sequence as described below has been compiled directly from the data derived by the study of the well logs of the field. These wells Include only the formations down to the Dundee, the producing horizon. Newcombel and others2 have already described the stratigraphy INewcombe, R. B., Oil and gas fields of Michigan: Michigan Geol. and Biol. Survey Pub. 38, Geol. Ser. 32, pp. 19-90, 1933. 2 Lane, A. C., and Seaman, A. E., Notes on the geological section of Michigan: Jour. Geology, vol. 15, p. 686, 1907. 4mith, h. A., A report on Michigan limestones: Michigan Geol. and Biol. Survey Pub. 21, Geol. Ser. 17, Prt II, pp. 153-257, 191. 4. in detail and it is only in certain refinements that the present data is original. The pre-Cambrian rocks that under- lie unconformably the sedimentary rocks of the Michigan synclinal basin are of igneous and metamorphic varieties. The total thickness of the Paleozoie sedimentary rocks in the central portion of the basin is probably over 12,000 feet. They consist of sandstones, shales, and limestones. The rocks of Cambrian age, known principally from outcrops in the Upper Peninsula, are sandstones with a thickness of about 1500 feet. The Ordovician system also does not outcrop in the lower peninsula but it has been penetrated by drilling and has an estimated thickness of 1600 feet. It is made up of shale and limestones with thin beds of sandstones. The possible oil horizon in this system is the Trenton formation of middle Ordovician age. This is a massive dolomitic limestone with an average thickness of 600 feet. The Silurian rocks of Michigan are largely limestone, dolomite, salt, and gypsum. The conditions of evaporation that caused the salt and gypsum deposits are duplicated several times during the remainder of the Paleozoic era in Michigan. Devonian 51 tem The Devonian period began with the deposition of a basal sandstone and ended with the formation of beds of black and gray shales and dolomitic limestones. These beds 5. have been divided into a number of formations, of which the bylvania sandstone is the lowest. In places it is absent, but elsewhere ranges in thickness up to 300 feet. The Detroit River series overlies the Sylvania and consists of dolomite, gypsum, and salt. It has an average thickness of 800 feet. The next two higher formations, the Oriskany and Mackinac consists of sandstone, oherty limestone, and dolomite. There is some doubt as to the correlation of the Oriskany with the true Oriskany of surrounding states. The doubtful Oriskany is only 5 feet thick and is overlain by the Mackinac, Which may hpve a maximum thickness of 300 feet, but again may be totally absent. The Dundee formation which overlies the Mackinac unconformably and is the producing horizon of the Porter oil field, varies in thickness from 300 feet in the Saginaw region to 50 feet in central and western Michigan. The irregularities of the Mackinac erosion surface on which the Dundee was deposited, together with an episode of erosion at the close,of Dundee deposition, accouht for the varying thickness of the latter. The Dundee of the northern part of the state does not correlate with the Dundee in the southern part and there seems to be a different fauna present in the two regions. These faunal elements are thought to be due to the presence of local basins and barriers during deposition. The lithologic characteristics are similar throughout the state. The rock is gray to buff, cherty, crystalline, fossiliferous limestone. There is a 6. dolomitic bed near the base that grades into a sandstone in some localities. The porous zones that serve as reservoirs in the oil producing areas also are dolomitic and contain much bituminous matter. A drilling sample from the producing horizon may be a buff-colored limestone, but upon treatment with HG1 acid, will yield globules of oil. The Bell shale occurs above the Dundee at the base of the Traverse formation and regionally is a wedge shaped formation thinning to the southwest. The shale is a blue gray to dark gray calcareous rock, usually black at the base. It is locally absent and in these places it is very difficult to distinguish the base of the Traverse from the top of the Dundee. The thieknesw of the shale varies from 60 to 80 feet but in many of the well logs the drillers either fail to recognize the Traverse- Bell contact or place the top of thefell shale up in the lower shale bed of the Traverse. The Traverse formation occurs without a break throughout the Elohigan basin. It ia made up of alternating beds of shale, limestone, and dolomitie limestone. It has a eharacteristic blue color that helps to distinguishhit from the more buff colored Dunclee below. The average thicknese for the central lichigan area is about 600 feet. The top of the Traverse is very irregular and probably represents an errosional surface. The Antrim shale is a dark brown to black shale containing many concretions of pyrite and bituminous 7.