Digitized by the Internet Archive in 2018 with funding from University of Illinois Urbana-Champaign https://archive.org/details/oilinvestigation00illi_1 STATE OF ILLINOIS STATE GEOLOGICAL SURVEY FRANK W. DeWOLF, Director BULLETIN No. 31 OIL INVESTIGATIONS IN ILLINOIS IN 1914 Area south of the Colmar oil field By William C. Morse and Fred H. Kay The Colmar oil field—a restudy By William C. Morse and Fred H. Kay The Allendale oil field By John L. Rich Anticlinal structure in Randolph County By Stuart Weller Oil and £as in Gillespie and Mt. Olive quadrangles By Wallace Lee Work in cooperation with U. S. Geological Survey ILLINOIS STATE GEOLOGICAL SURVEY UNIVERSITY OF ILLINOIS URBANA 1915 Tf< I H t ,> py PRESS DECATUR. ILL j^rs-? Qb-3/ a, & STATE GEOLOGICAL COMMISSION Edward F. Dunne, Chairman Governor of Illinois Thomas C. Chamberlin, Vice-Chairman Edmund J. James, Secretary President of the University of Illinois Frank W. DeWolf, Director Fred H. Kay, Asst. State Geologist LETTER OF TRANSMITTAL State Geological Survey i University of Illinois, April 26, 1915 Governor E. F. Dunne, Chairman, and Members of the Geological Commission. I submit herewith a report on oil investigations during 1914 and recom¬ mend that it be published as Bulletin No. 31. The first two papers, by W. C. Morse and Fred H. Kay, relate to the new oil fields of western Illinois which were first surveyed in 1912 and proved productive near Colmar in 1914. A restudy of the original area is presented, and also a detailed report on new territory south of the Colmar field, which was surveyed last season. Another paper prepared for the bulletin by J. L. Rich relates to the comparatively new Allendale field in Wabash County. The fourth paper, by Stuart Weller, describes a prominent anticlinal fold in Randolph County, which is believed to merit drilling in search of oil or gas. The last paper by Wallace Lee of the U. S. Geological Survey, in cooperation with this office, outlines the possibilities of oil and gas accumu¬ lation in the Gillespie and Mt. Olive quadrangles of Macoupin, Mont¬ gomery, and Bond counties. The producing fields near Carlinville and Litchfield are described in detail. Oil production in Illinois continues to be second only to that of coal. The old fields are nevertheless on the decline, and new areas must be dis¬ covered if important production is to continue. The Geological Survey is devoting much attention to the problem. Very respectfully, Frank W. DeWolf, Director CONTENT S Page THE AREA SOUTH OF THE COLMAR OIL FIELD. 8 THE COLMAR OIL FIELD. 37 THE ALLENDALE OIL FIELD. 57 ANTICLINAL STRUCTURE IN RANDOLPH COUNTY. 69 OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES. 71 ( 6 ) Scolti 40 90 • OO Fig. 1. Map showing area covered in first two reports. THE AREA SOUTH OF THE COLMAR OIL FIELD I3y William C. Morse and Fred H. Kay (Field work by William C. Morse and John L. Rich) (In cooperation with the U. S. Geological Survey) OUTLINE Page Introduction . 10 Acknowledgments . 10 Personnel of the party. 11 Method of field work. 11 Key rocks. 11 Stratigraphy. 12 General statement. 12 Unconsolidated rocks. 12 Alluvium. 12 Loess . 13 Drift .•. 13 Consolidated rocks. 14 General description. 14 Carbondale formation. 17 Pottsville formation. 18 St. Louis limestone. 19 Salem formation. 21 Warsaw formation. 21 Keokuk limestone. 22 Burlington limestone. 22 Kinderhook and Upper Devonian shale. 23 Devonian limestone. 23 Niagaran dolomite. 23 Ordovician formations. 23 Position of Hoing sand in the section. 24 Structure . 24 General statement. 24 Relation of folds in oil-bearing stratum to accumulation. 26 Detailed structure. 29 General statement.•. 29 Folds shown by coal No. 2 and St. Louis limestone. 30 Recommendations . 31 Localities already tested. 34 ( 8 ) ILLUSTRATIONS PLATE PAGE I Map of parts of Schuyler, Brown, Adams, and Hancock counties. 28 FIGURE 1. Map showing area covered in first two reports. 7 2. Loess in the west bluff of Illinois River below Frederick. 12 3. Loess hills near Frederick. 13 4. Graphic sections (1) from measurements on outcrops; (2) log of Hoing No. 1 well. 16 5. Colchester (No. 2) coal and overlying black shales west of Rushville. 17 6. Unconformity at base of Pottsville, Harrison Branch. 18 7. St. Louis limestone east of Birmingham. 19 8. Caves in St. Louis limestone filled by Pottsville sands. 20 9. Erosion planes in St. Louis limestone, Harrison Branch. 20 10. Keokuk limestone near Plymouth. 22 11. Diagram showing significance of unconformities. 25 12. Diagrams showing conditions governing oil accumulation. A. In oil sands saturated with salt water . 27 B. In oil sands partly saturated . 27 C. In sands containing no salt water . 27 TABLES PAGE 1. Drill holes in area south of Colmar field. 35 ( 9 ) INTRODUCTION Oil was discovered on the J. Hoing farm on April 30, 1914 in what is now known as the Colmar Oil Field, an area suggested as favorable for the accumluation of oil or gas in a joint report of the United States Geologi¬ cal Survey and the State Geological Survey by Henry Hinds 1 . To date more than 130 producing wells have been completed and the output is now approximately 650 barrels per day. In the hope of locating other areas in which the geological structure is favorable for the accumulation of oil or gas the work during the past season has been pushed on to the south. The new territory now completed (see figure 1) includes the whole of Schuyler County except the small point east of Sugar Creek; the adjoining part of Brown included roughly within lines running from Ripley to Mt. Sterling and from Mt. Sterling to Damon ; and the adjacent belt on the west, one to three miles broad, in Adams and Hancock counties. Acknowledgments An introduction to the geology of this part of the State was given by Dr. Stuart Weller, accompanied by Mr. F. M. Van Tuyl of the Iowa Survey, who met Messrs. Morse and Rich at Keokuk, Iowa, visited the type localities of the Keokuk and Warsaw formations and made with them a three-day reconnaissance automobile trip through McDonough, Schuyler, and Brown counties. Acknowledgment must also be made at the outset to Dr. John L. Rich, who was a collaborator in the study of nearly the whole of Schuyler County, and who assumed the extra duty of directing the instrument men. He would have been joint author had he not been called east before the areas in Brown, Adams, and Hancock counties and the Colmar field were studied. Free use has been made of the report of Mr. Henry Hinds of the U. S. Geological Survey, which was published under a co-operative agree¬ ment by the State Survey. Mr. Raymond S. Blatchley located and deter¬ mined the elevations of about 15 producing wells and a similar number of dry ones in the Colmar field. He also secured a large number of well records which the senior author was unable to obtain because of lack of time. A friendly cooperation was manifest on every hand, both by the owners of the farms and the oil men. Free camp sites and automobile storage, one or both, were furnished by Mr. W. C. Blackburn of Brooklyn, Mr. Roy Moore of Rushville, Mr. Hare of Mt. Sterling, and Mr. Henry Pearson minds, Henry, Oil and gas in the Colchester and Macomb quadrangles: Ill. State Geol. Survey, Extract Bull. 23, pp. 11-13, 1914. ( 10 ) THE AREA SOUTH OF THE COLMAR OIL FIELD 11 and son of Augusta. Well records and other information were freely given by Messrs. Page and Crew of the Ohio Oil Company, Mr. Glass of Snowden Brothers and Company, Mr. B. A. Kinney of the Lamoine Oil and Gas Company, Mr. Frank Lawler, representing Messrs. J. B. and W. H. Hazlett, Mr. P. B. Lamberton of Lamberton and Baker, Mr. Lewis of J. E. Urschel and Company, and others. Personnel of the Party The party, in addition to Messrs. Rich and Morse, included at various times: David E. Day, John D. Mattison, J. Philip Pepper, H. S. Eisu, Victor Wood, Paul F. Morse, J. Hazlette Bell, Harold R. Moore, James A. Lee, Jas. H. Pierson, L. W. Robison, Jas. Barger, Ray Post, Harry A. Almond, and J. W. Hemphill. Method of Field Work Since the beds in the area lie approximately parallel to one another, the position and altitude of any underlying stratum such as an oil sand, can be learned by determining the position of any persistent recognizable bed ex¬ posed at the surface. The position of the oil sand bears a direct relation to the accumulation of petroleum, as explained under “Relation of geologic structure to oil and gas accumulation;" and in the region under consideration, instrumental levels were run to outcrops of certain beds that could be somewhat easily recognized by the geologists. An attempt was made to find outcrops not more than one mile distant from one another. Field work began July 1 and continued to November 1. It was conducted from camp, and an auto¬ mobile was used to great advantage. The levelman and two rodmen were taken to their work in the morning and the car was then available for the geologists in scouting for outcrops. Flags consisting of cheesecloth 18x18 inches on a lath staff, were placed upon the exposures. The location of the flag was usually determined by means of a Brunton compass and by pacing to the nearest land or road corner, and its position and number were noted on the map. A similar map or a tracing, together with detailed information concerning the flag locations, was furnished the levelman for his guidance. Key Rocks Coal No. 2 (Colchester or Murphysboro) was found to be the most useful key rock because it had been opened up at many places where all consolidated rocks were otherwise covered by glacial deposits. Further¬ more, information about the coal was more readily obtained than that con¬ cerning any other bed. Since the St. Louis limestone is commonly harder than the overlying and underlying beds and was rather easily discovered, its 12 OIL INVESTIGATIONS base was frequently used as a key horizon. In the vicinity of Rushville the Springfield (No. 5) coal, lying 120 to 130 feet above the coal Xo. 2, was followed ; elsewhere other beds were used to a limited extent. STRATIGRAPHY General Statement The rocks of the area under discussion belong to two distinct types: namely, (1) unconsolidated and (2) consolidated. The unconsolidated rocks consist of material deposited by the present streams and called alluvium; that transported by the wind and designated as loess; and that deposited by the continental ice sheet and known as drift. The consolidated rocks are much older, were deposited earlier, and are such ordinary kinds as sandstones, limestones, and shales. Unconsolidated Rocks alluvium The alluvium is confined for the most part to the present valleys, where its thickness ranges from a few feet to 80 or more. It is for the most part clay or sand or a mixture of both of these, but at some places is coarser material. It is the first material penetrated in most of the wells which are located in the valleys. LOESS Over the drift in many places is a covering of fine material known as loess which is believed to have been carried and deposited more or less exclusively by the wind. As a rule it is thicker along the bluffs overlooking the larger valleys, and thinner farther back from the streams. Because of this localized distribution and peculiar composition, which in some cases, at least, is very similar to finely ground glacial material or rock flour, the loess is believed to have been swept out from the glaciers by streams, spread out over the flood plains, and then after the floods subsided and the material became thoroughly dry, picked up and deposited over the neighboring uplands by the wind. In texture it is intermediate between clay and sand. Although unconsolidated, when undercut it is capable of standing in vertical or slightly overhanging clififs (see figure 2). Another characteristic is its division by joint planes into vertical columns. The thickness of the loess, like that of the drift, varies from place to place; but in the area under discussion it is especially thick along the western bluffs of Illinois River (see figure 3). THE AREA SOUTH OF THE COLMAR OIL FIELD 13 Fig. 2. Loess in the west bluff of Illinois River below Frederick. Fig. 3. Loess hills above the outwash plain, looking toward Illinois River near Frederick. DRIFT The drift belongs to one of the earlier periods of glaciation, the Illinoian. Nearly everywhere in this area it conceals the bed rock and adds much to the labor of the geologist in determining the position of the bedded rocks. The drift contains fragments of many kinds of rock (limestone, sandstone, granite, gneiss, schist, and others) over which the glacier or ice sheet passed. 14 OIL INVESTIGATIONS In places the constituents are assorted into clay, sand, gravel, and bowlders; and in others they may be mixed together in a heterogeneous mass. In this area the drift is for the most part fine material containing few large bowlders. At most places outside of the valleys the drift is the first material penetrated by the drill and in places the presence of bowlders in the soft material deflects the drill so as to produce a crooked hole which has to be abandoned. Consolidated Rocks GENERAL DESCRIPTION The consolidated rocks of interest to the oil operator in this region include the formations from the lower part of the “Coal Measures” down to the St. Peter sandstone which underlies the Trenton limestone. At different places in the area all of the formations down to, and includ¬ ing, the Keokuk limestone are exposed and may be studied in detail. Below the Keokuk the beds are known from samples obtained by drilling. The inserted generalized section serves as a key to identify the forma¬ tions on the outcrop or in drillers’ records. The following is a composite section from measurements of various outcrops in the region. Composite section of exposed rocks Pennsylvanian series Carbondale formation Ft. In. A. Limestone, nodular, bluish black. 6 B. Shale, hard, black, carbonaceous, slate-like, with nodules or concretions of hard, dark limestone. Large Lingulae and Orbiculoidece . 2 6 C. Coal, Springfield (No. 5), broken by clay seams and slightly faulted. Mined. The Mt. Sterling 18-inch bed is probably the same. 5 D. Commonly covered, the exposed portions consisting of shales and underclay. 7 E. Limestone, nodular or brecciated. Exposed at Mt. Sterling, but not noted so fully developed at other places. 3 F. The first interval of twenty or thirty feet beneath the Springfield (No. 5) coal is commonly covered. Sandy shales and shaly sandstones, the layers of which in places thicken up and form more massive sandstones. In places cementation has been more pronounced, resulting in harder and more resistant layers. In still other places more thorough cementation has developed large flat con¬ cretions, which are more conspicuous where weathering has removed the adjacent parts of the layers. Massive sandstone in places, shales in others. The uneven erosion THE AREA SOUTH OF THE COLMAR OIL FIELD 15 Ft. In. surface at the base probably represents an unconformity. More or less of the whole interval of 100 feet from the Springfield (No. 5) coal to the limestone below is subject to variation in constitution. 90 G. Limestone, dark gray. Ranges from 6 inches to 7 feet in thickness and is nodular in places. Contains Chonetes mesolobus, Productus, Crinoids, and other fossils. 4 H. Shale, hard, black, carbonaceous, and slate-like, which may be somewhat softer at the base. It contains flat and spherical concretions of dark limestone; Orbiculoidece and Lingulcz are common. 4 I. Shales, soft blue clay; at some places 16 or 18 feet thick and at others only 2 or 3 feet, or wanting. This irregu¬ larity in thickness is due to irregular deposition. The bed of black shales above is wavy as a result of this variation 12 J. Coal, Colchester (No. 2), mined. This coal with the overlying black shale and limestone is the most constant horizon in the Pennsylvanian in this part of the State.... 2 6 Pottsville formation K. Underclay and shaly clay. 2 6 L. Shales, soft clay, 1 to 10 feet in thickness. 6 M. Limestone, nodular, conglomeratic, or brecciated. 3 N. Clay or shale or shaly clay which becomes more sandy toward the bottom and passes into sandstones. This is the Cheltenham clay horizon, the clay being especially well developed and valuable at some places. 14 O. Coal which ranges from 6 inches to 18 inches in thickness and which may consist of two beds. It is commonly called No. 1. 1 P. Shales, blue, clayey, and sandy, grading into sandstones.... 15 Q. Sandstone, irregular with some sandy shale. 5 Marked unconformity Mississippian series St. Louis limestone R. Limestone, hard, bluish gray. Portions of the limestone are in regular layers, and other portions are decidedly irregular. In places the limestone is brecciated, the angular pieces being almost exclusively limestone, and in others the limestone is decidedly sandy. In the lower part of the formation lenses of sandstone are present which seem to be formed of sand which was washed into cavities . 20 Salem and Warsaw formations Thin- to thick-bedded sandy limestone or dolomite. Resembles very fine-grained, limy sandstone. Generally has yellow to brownish-yellow tint. Toward base is compact, bluish limestone. Dull sound when struck with hammer; this characteristic is helpful in distinguishing Salem from St. Louis which rings when struck. 18 16 OIL INVESTIGATIONS Feet 72 73 120 25 92 23 Oil sand Fig. 4. Graphic sections : j. From measurements on outcrops (see “Composite section, page 14). 2 . Log of Hoing No. 1 well. THE AREA SOUTH OF THE COLMAR OIL FIELD 17 Ft. In. Limestone, shaly, and blue, shales, some of which are filled with fragments of bryozoans and small shells. Small geodes are present in places. 24 Base not exposed. Underlying Keokuk limestone exposed in region but no continuous section from Salem downward could be found. Figure 4, section i is a graphic representation of the section given above, including the beds to the base of the St. Louis limestone. By taking No. i in connection with the graphic log of the Hoing well on the left, (No. 2 ), the reader may gain a definite idea of the beds to be penetrated in drilling to the oil “sand”. CARBONDALE FORMATION The Carbondale formation includes all of the beds from the top of coal No. 6 down to the base of coal No. 2. The former coal is not present in the area under consideration. Exposures at few places show beds higher than a few feet above coal No. 5, which lies 50 to 100 feet below coal No. 6 in other parts of the State. Fig. 5. Colchester (No. 2) coal and overlying black, concretionary shales west of Rushville. In the vicinity of the Colmar oil field most of the coal-bearing rocks were eroded before glacial times, and in many places the first rocks under the drift are Mississippian limestones. Toward the south and east, the 2—B—31 18 OIL INVESTIGATIONS Carbondale is present in greater thickness. Near Pleasant View 130 feet of this formation was measured. The Carbondale consists largely of shales and sandstones, but it also contains thin beds of limestone, underclay, and coal. Coal No. 2 (Colchester) is one of the most persistent beds of the Pennsylvanian series in Illinois. In spite of its thickness of only 24 to 30 inches, it has been opened up at many places along the outcrop. Directly above coal No. 2 or separated from it by a few feet of soft, clay shales, is a bed of hard, black, carbonaceous, slate-like shale similar in appearance to that above the Springfield (No. 5) coal (see figure 5). It contains nodules of hard, dark limestone and fossil Orbiculoidea and Lingula which are smaller than those in the shales associated with coal No. 5. Above the black shales is a stratum of fossiliferous limestone, here and there chert-like. In this phase the fossils appear white against the dark background. Coal No. 5, which is confined to a small area north of Rushville and Pleasant Mew is commonly 5 to 6 feet thick and contains clay seams that cut across the bedding planes of the coal. The beds above coal No. 5 are very similar to those above coal No. 2. The roof is a hard, black shale overlain by a nodular limestone containing fossils. In the shale are nodules and fossil shells of Orbiculoidea and Lingula which are larger than those in the shale above coal No. 2. Below the floor clay of coal No. 5 is a nodular limestone not unlike that beneath the Colchester coal. POTTSVILLE FORMATION The Pottsville formation includes all beds from the base of coal No. 2 to the base of the Pennsylvanian series. Like the Carbondale formation it too is made up for the most part in this region of shales and sandstones, but contains minor amounts of limestone, underclay, and coal. A few feet Fig. 6. Unconformity at base of Pottsville, Harrison Branch, north of Huntsville. The diagram above point marked “X” represents hillside outcrops, that below “X" repre¬ sents longitudinal section of stream bed. beneath coal No. 2 is a bed of limestone which is either nodular or brecciated and is not unlike the St. Louis, but can be readily distinguished from it where fossils are present. A thin coal is found beneath coal No. 2 at many THE AREA SOUTH OF THE COLMAR OIL FIELD 19 places, but owing probably to its lenticular nature no single bed persists over a large area. The “Coal Measures” rocks were deposited on a former land surface with hills and valleys; consequently the thickness is extremely variable. The Pottsville formation lies at some places on the St. Louis limestone, at others on the Salem formation, and elsewhere on still older formations. Such a relationship is called an unconformity since the normal sequence of deposition has been interrupted by a period of erosion. Figure 6 is a sketch showing the unconformity at the base of the Pottsville in Harrison Branch, north of Huntsville. ST. LOUIS LIMESTONE In most places the St. Louis is a brecciated, poorly bedded limestone. Well-defined layers are exceptional. Most of the angular fragments are limestone and vary in size from grains to blocks 2 feet or more in diameter (see figure 7). The color is blue at most places, although here and there a Fig 7. Brecciated and conglomeratic St. Louis limestone east of Birmingham. yellowish tint is noticeable. The limestone is barren of fossils, except large hemispheres of the coral Lithostrotion canadense, which are harder than the surrounding stone and must have collected as residual material on the old St. Louis surface as the limestone weathered away, since most of them are now in the base of the Pottsville sandstone. When the St. Louis was land surface, caverns were formed in the limestone as the result of solution by acid waters, just as caves now form 20 OIL INVESTIGATIONS in limestones. Later the Pottsville was deposited on the St. Louis, and some of the sand settled down into the old caves as shown in figure 8. The St. Louis commonly has a thickness of 18 to 20 feet but in places Fig. 8. Caves in St. Louis limestone filled by Pottsville sands. (Photo by Rich) Fig. 9. Erosion planes in the St. Louis limestone in Harrison Branch north of Huntsville. it reaches more than 30 feet. In many parts of the regi n it has been completely removed by pre-Pottsville erosion. THE AREA SOUTH OF THE COLMAR OIL FIELD 21 The surface on which the St. Louis was deposited was not rough ; the greatest departure from a level noted is 8J4 feet in a horizontal distance of 100 feet in Williams Creek about 3 miles northwest of Huntsville. Besides the unconformities at the top and bottom, the St. Louis contains erosion planes as shown in figure 9. SALEM FORMATION Below the St. Louis, and in unconformable contact with it, is a variable thickness of yellowish, magnesian limestones, limy shales, and limy sandstones correlated with the Salem formation. In many places difficulty is experienced in correctly classifying the material as limy sand¬ stone or as impure limestone. Geodes are abundant , but fossils are scarce. When struck with a hammer the Salem gives a dull sound, in decided contrast to the ringing sound of the St. Louis limestone. Thirty feet or more of the Salem was measured in the region, but because of the unconformities at top and bottom, and also because of the similarity between the basal beds of the Salem and the top strata of the Warsaw, the thickness of the former is uncertain. The following section is typical of the Salem in this region. 5. 4. 3. 2 . 1 . Measured section of Salem formation along stream and road between secs. 5 and 6 , T. 2 N., R. 3 W. Ft. Limy shales, impure, yellowish, and bluish, and impure yellowish limestones with chert and quartz geodes at a number of horizons. The layers are more massive at the base. 20 Not exposed, probably shale. 12 Shales, blue. 4 Limestone, impure and yellowish, with bryozoa and Productus . 4 Clay shale, blue; and sandstone. 3 In. 6 6 WARSAW FORMATION The Warsaw formation in this region is composed of 30 to 40 feet of interbedded blue clay shales, and thin, impure limestones. The shales contain abundant bryozoans, and in the limestones a large spiral fossil of this class known as Archimedes is very characteristic. The following sections show the variable nature of the Warsaw in this region. They probably include some of the overlying Salem since it is impossible to determine the contact between the two. Section of part of Warsaw formation in the south central part of sec. 14 , T. 3 N., R. 4 W. (Section may contain few feet of Salem formation) Ft. In. 3. Clay shales, hard, blue; and sandstones with very little lime, yellow, and like Salem at base. 8 22 OIL INVESTIGATIONS Ft. In. 2. Limestone, crystalline, massive, grading up into sandy limestone, yel¬ low ; large Archimedes . 10 1. Clay shales, soft, blue, and fossiliferous. 2 6 Section of part of Warsaw formation in the NE. cor. sec. 26 , T. 3 N., R. 4 W. Ft. In. 2. Limestone, thick, reddish brown, crystalline, with sandstones between. The upper limestone contains a large roseate brachiopod and the lower one contains Archimedes, corals, and brachiopods. 12 1. Clay shales, soft, blue, filled with bryozoans, brachiopods, pelecypods, and Archimedes . 5 KEOKUK LIMESTONE The Keokuk limestone is the lowest formation exposed in the region. It consists of 30 feet or more of gray, crystalline, very fossiliferous lime¬ stone, which grades upward into the Warsaw shales. The main body of the Keokuk is evenly bedded as shown in figure 10. Fig. 10. Keokuk limestone near Plymouth. (Photo by Rich) BURLINGTON LIMESTONE The Burlington limestone does not outcrop in the region, but it is believed to be represented by certain cherty limestones penetrated by the drill while passing through the base of the Mississippian or so-called “first lime”. In the Littleton well, recently drilled, the lower part of the lime¬ stone from 270 to 445 probably represents the Burlington. THE AREA SOUTH OF THE COLMAR OIL FIELD 23 KINDERIIOOK AND UPPER DEVONIAN SHALE The “first” and “second” limes are separated by about 200 feet of shale. The upper 100 feet, usually a bluish-gray, sandy shale, represents the Kinderhook. Samples from the Littleton well show 100 feet of Kinderhook shale underlain by 100 feet of dark gray to olive shale containing Sporangites which prove it to be of Upper Devonian age. The lower part contains shales of somewhat lighter color. DEVONIAN LIMESTONES A thin, non-magnesian limestone usually reported as gray, and in some places said to contain pyrite, underlies the shale mentioned above. In most of the wells thus far drilled this limestone is not more than 15 feet thick, although it is difficult to distinguish from the underlying limestone. It forms the upper part of the drillers’ “second lime.” NIAGARAN FORMATION Below the limestone described above is a gray to pink crystalline dolo¬ mite which probably represents the Niagaran. Where it is present, it forms the lower part of the “second lime” and would probably not be distinguished from the Hamilton limestone above. Since the Niagaran was deposited on an eroded surface of Maquoketa shale and was itself exposed to erosion before the overlying Hamilton was deposited upon it, the thickness of the Niagaran is extremely irregular. In some places it was completely eroded. The combined thickness of the Hamilton and Niagaran is rarely more than 50 feet. In the western part of Illinois, the Niagaran is closely associated with oil production. It contains the gas in Pike County, where the dolomite is also oil soaked in places. On the outcrop in Calhoun County near Batch- town, the Niagaran is a fine-grained, bufif-colored dolomite that falls to powder under the hammer, and is so porous that it could easily act as a reservoir for oil and gas. The “broken” sand so often reported at the base of the “second lime” is probably the porous basal part of the Niagaran. The oil sand probably represents reworked material at the base of the Niagaran and is properly classed as part of that formation. ORDOVICIAN FORMATIONS Below the Niagaran the drill penetrates a variable thickness of shale, generally bluish or greenish and usually easily distinguished. In the Griggsby well in the W. y 2 SE. % sec. 20, T. 4 N., R. 4 W. the Maquoketa or Richmond shale as it is called, is 187 feet thick and in other wells that penetrate the formation, it generally ranges from 180 to 200 feet. Recent 24 OIL INVESTIGATIONS drilling seems to indicate that 6 or 8 miles north of the Colmar field, the Maquoketa may be much thinner than indicated above; probably on account of erosion before the Hamilton was deposited. In the latter area the Maquoketa also contains shaly textured dolomites in contrast to the typical shales further south. Below the Maquoketa is the Kimmswick-Plattin (Trenton) limestone which in the region covered by this report is non-magnesian, gray, and somewhat crystalline. Thus far it has not been found to contain oil in the western part of Illinois. South of this region, in Calhoun County, the Trenton outcrops and is seen to be composed largely of shells. When struck with the hammer, the odor of oil is very prominent. About \y 2 miles north of Beechville, Calhoun County, the Trenton contains a conspicuous amount of bituminous matter. The rock must have been highly organic originally, and it is not unlikely that some oil originated in this formation. Drillers in Illinois often report the odor of petroleum from the Trenton. It was penetrated 200 feet in Griggsby No. 1 and it may be 300 to 400 feet thick. Because of its compact nature, it does not tend to be as favorable for accumulation as does the more porous A T iagaran, but it should be tested in wells where the structure is favorable in order to explore all possible oil horizons. Position of the Hoing Oil Sand in the Section The producing stratum lies beneath the “second lime” and at the base of the Niagaran formation. Samples from producing wells show that it is a round-grained quartzitic sand of variable thickness. The sand exists in lenses and appears to be material that was washed into the valleys and low areas when the Maquoketa shale was land surface and exposed to erosion. It was reworked, of course, by the Niagaran sea. Its areal distribution is spotty and in many places the drill passes from the “second lime” directly into the Maquoketa shales, with no intervening sands. It is possible that the lower part of the Niagaran dolomite is in some places responsible for a show of oil but it is believed that important accumu¬ lation is dependent on the presence of the more porous sand. It is obvious that the presence of the latter cannot be predicted in advance of the drill. STRUCTURE General Statement The significance of the unconformities described under “Stratigraphy” is shown graphically in figure 11, the unconformities being represented by the irregular contact lines between different formations. Such contact planes are simply ancient land surfaces, some of which had almost as THE AREA SOUTH OF THE COLMAR OIL FIELD 25 much relief as the surface today; whereas others exhibit a relief of only a few feet. In selecting a key rock the elevation of which is to be determined throughout a region, in order to learn the position of underlying oil sands, it is necessary to know that the bed is approximately parallel to the deeper beds or that the departure from parallelism is regular and determinable. An unconformable contact between two formations is worthless for this purpose in Illinois if the irregularities in the old surface as shown by the plane of contact exceed 15 feet. For example, the contact between the “Coal Measures” and the Mississippian limestones or “first lime.” as shown in figure 11, would be valueless in determining the position of the Hoing Fig. 11. Diagram showing significance of unconformities in the Colmar region. sand, since levels on this contact would merely determine the height of the hills on the old land surface rather than any folding which the beds had undergone. On the other hand, the base of the St. Louis limestone, although 26 OIL INVESTIGATIONS in unconformable contact with lower formations, serves as a safe horizon because the irregularities in the plane of contact are slight. So far as is known, regardless of the many oscillations of the region above and below sea level and despite the long periods of time represented by the formations and their unconformities, there was practically no warping or folding of the beds from the time the Hoing sand was deposited until after the “Coal Measures’’ were laid down. Such folding as then took place affected all the beds alike. Were it not for this fact, geological work on beds at the surface would be almost useless in determining underlying structures. During the submergence which followed the exposure of the St. Louis limestone as a land surface, it is possible that the sinking was slightly greater toward the northwest since we now find in that direction an increasing interval between the base of the St. Louis and coal Xo. 2 lying above. The interval varies from about 45 feet in southeast Schuyler County to about 75 feet in the vicinity of Colchester. Relation of Folds in an Oil-bearing Stratum to Accumulation In most of the oil fields of the State, the accumulation is intimately connected with the upward folds in the strata. It is the usual experience to find the oil near the crests of the anticlines or where terraces exist on the sides of the anticlines. Both types are illustrated in the main oil fields of Lawrence and Crawford counties. The fact that every known field in Illinois is surrounded by wells which tap only salt water, is strong evidence that the latter is a most important factor in determining where the «oil will accumulate in a sand that has been folded in undulations. If the sand is practically saturated with salt water, the result is generally a forcing of the oil int} the crest of the fold as shown in figure 12, A. In case of partial saturation, the oil is found farther down the sides of the folds and the crest may be dry or it may contain some gas (fig. 12, B). If the sand is dry, the oil is per¬ mitted to collect in the basins or synclines, and the anticlines prove unpro¬ ductive (fig. 12, C). The productive part of the sands in the southeastern Illinois fields is near the crest of the well-defined La Salle anticline or on terraces which are part of this same fold. On the sides of the anticline, salt water fills the producing sands almost to the crest. In the western part of Illinois, however, many of the conditions are different from those in the fields just mentioned, and it would not be sur¬ prising if oil is found in positions entirely different from those better known heretofore. In attempting to locate possible undiscovered fields in western Illinois the following facts must be given due consideration: THE AREA SOUTH OF THE COLMAR OIL FIELD 27 1. The structural features—that is, folds—are small in area and in magnitude. The crests of many of the domes and anticlines are not more than 20 or 30 feet high. 3rd.drill hole Fig. 12. Diagram showing conditions governing oil accumulations: A. In oil sands saturated with salt water. B. In oil sands partly saturated. C. In sand containing no salt water. 28 OIL INVESTIGATIONS 2. The oil-bearing horizon is extremely variable in thickness and in character. 3. Drilling already done shows that oil and salt water exist in separated areas and at so widely different elevations that no lateral connection be¬ tween the deposits of one area with another is conceivable. 1. In the eastern part of Illinois the beds at the crest of the La Salle anti¬ cline lie 500 feet higher than in the basins bordering the fold. The anti¬ cline is of sufficient magnitude to be easily identified and traced, and its influence on petroleum accumulation is clearly defined. In the western part of the State, however, the beds dip gently eastward, and the folds that have developed are merely small irregularities in, or interruptions to, the general dip. The altitude of the sand has been determined from outcrops of beds at the surface, the parallelism of the strata being assumed. In the Colmar field, the sand is parallel to the beds lying above and shows the same folding as the coal. How¬ ever, the drilling of domes and anticlines where the crests rise only 20 or 30 feet, is recommended with considerable hesitancy. 2. The sand that contains the oil was probably deposited only in the valleys and basins in the Maquoketa shale. Consequently the bed is not con¬ tinuous, but exists as lenses of various shapes and sizes, entirely separated from one another. This assumption is confirmed by the records from some of the wells in which little or no sand was found at the Hoing sand horizon. 3. The location of the salt water in the territory thus far studied presents a serious problem. In the Colmar field the sak water is found in the lower part of the sand on the terrace and also lower down the dip. At the east end of the crest of the elongate dome, the Collins and Griggsby wells showed a small amount of oil and no salt water; whereas at the west end of the dome the Roberts No. 1 well, which taps the sand at the same elevation as the wells named above, produces oil in commercial quantities and is surrounded by wells lower down the dome which produce only salt water, existing high in the dome, almost 50 feet above the level of the oil in the Colmar field only three miles distant. In the vicinity of Birmingham, and between this place and Augusta, a number of wells have been drilled, and although the Hoing sand was found in most of them and notwithstanding the fact that the highest of these wells structurally, taps the sand at least 60 feet below the salt water near the Roberts No. 1 well, careful investigation discloses the absence of salt water in the lower wells. In fact, below about 100 feet where fresh water required casing, it was necessary to add water to most of these wells for drilling purposes. It is clear then that regardless of position above sea level, certain areas may be saturated with salt water and possibly with accompany- SURVEYED IN COOPERATION WITH U. S. GEO -OGICAL SURVEY ILLINOIS STATE GEOLOGICAL SURVEY GOVERNOR E F. DUNNE. T. C. CHAMBERLIN, E. J. JAMES. COMMISSIONERS FRANK W. DE WOLF, DIRECTOR BULLETIN NO. 31. PLATE I I Beardatown R. 1 W. MAP OF PARTS OF SCHUYLER, BROWN. ADAMS AND HANCOCK COUNTIES SHOWING POSITION OF UNDERLYING BEDS BY MEANS OF CONTOURS ON COAL NO. 2 By William C. Morse and John L. Rich. 1915. THE AREA SOUTH OF THE COLMAR OIL FIELD 29 ing trapped oil, whereas between these areas there may be no oil nor salt water. The explanation of the features mentioned is probably to be found in the fact that the sand now exists in separated lenses surrounded at the sides as well as at the top and bottom by impervious beds, and accumulation is free to progress in each lens independently as outlined under the topic “Conditions governing accumulation in the Colmar field,” to which the reader is referred. Under these conditions the degree of saturation by oil and salt water will govern whether accumulation will take place at the top of the folds, in terraces lower down, or in the synclines. Taking all features into consideration, the Survey recommends that the first test holes be located near the crests of the domes and anticlines pointed out under the topic “Recommendations.” In doing so the operator will be prospecting the areas that are normally the most favorable. If the crests are found to be barren of oil and to contain no salt water, other wells should be drilled in positions to test the sand at lower elevations, preferably terraces as shown on the structure map. In locating wells on a flat portion of the sand (terrace) it should be remembered that the accumu¬ lation is likely to be at the downward-dipping edge of the terrace as shown in figure 12, B. Should the terraces prove barren of oil and salt water, it is recommended that at least a few of the synclines be drilled, the suppo¬ sition being that in the absence of salt water in the higher structures the oil would be in the troughs. Detailed Structure GENERAL STATEMENT Elevations upon either or both coal No. 2 and the basal contact of the St. Louis limestone were secured wherever possible at intervals of one mile or less. These elevations were recorded upon a study map which revealed the following general structure of the two beds. In general coal No. 2 dips to the south of east—from the highest ele¬ vation of 630 feet, in secs. 25 and 26, T. 3 N., R. 5 W. (Augusta), Han¬ cock County, to the lowest elevation of about 500 feet along Illinois River in the vicinity of Browning and Frederick, Schuyler County. Upon this larger structure in places there are some minor features which take the forms of small domes, anticlines, terraces, and synclines. The general dip, however, persists over large areas, and the coal bed lies nearly flat in a belt 4 to 6 miles wide stretching from Littleton to a point beyond Mabel (see Plate I) and probably in a similar belt stretching southeast from Little- toti through Rushville to Pleasant View, although elevations in this latter belt are very meagre because of the lack of coal outcrops. 30 OIL INVESTIGATIONS Like coal No. 2, the St. Louis limestone in the region under discussion, has a general dip to the south of east. It dips from the highest elevation of 580 or 590 feet in the vicinity of Huntsville and the northwest part of Schuyler County to the lowest elevation of about 450 feet along Illinois River between Browning and Frederick. Furthermore, the total amount of dip of these two horizons is about the same, being 130 feet for coal No. 2 and 140 feet for the St. Louis limestone. Upon this general structure of the St. Louis limestone there are also minor structural features similar to those shown by coal No. 2. Because of the general parallelism between coal No. 2 and the St. Louis limestone, and especially because in areas where exposures of the one are absent, outcrops of the other are commonly present, it has been regarded advantageous to combine the data regarding the two beds in a single map on which the altitude of the beds has been shown by means of contour lines. Where coal No. 2 is present the contours represent ele¬ vations run to that bed; where it has been eroded, its former elevation was determined by running elevations to the base of the St. Louis limestone and adding to this figure the average thickness of beds between the base of the St. Louis and coal No. 2. This thickness is 40 feet at the southeast part of the area and increases regularly toward the northwest as explained on page 26. At the northwest corner of Schuyler County the interval is 75 feet, as determined by Mr. Hinds in his work in the Colchester and Macomb quadrangles. FOLDS SHOWN BY COAL NO. 2 AND ST. LOUIS LIMESTONE A minor dome has been formed in the coal to the east of Littleton, its apex being in secs. 12 and 13, T. 3 N., R. 2 W. (Littleton). The bed in the immediate vicinity rises from about 550 feet on the southeast and from a little less than 580 feet on the north to its maximum elevation of about 600 feet. Both the St. Louis limestone and coal No. 2 between secs. 8 and 21, T. 2 N., R. 2 W. (Buena Vista), lie at elevations 10 to 20 feet higher than they do in the immediate vicinity to the north, east, and south, as indicated on the map (Plate I). It must be noted, however, that the rise of the beds is a very slight one. Coal No. 2 in secs. 14 and 9, T. 1 N., R. 2 W. (Woodstock), and the St. Louis limestone in sec. 33, T. 1 N., R. 2 W. (at Ripley), reach elevations 20 to 30 feet higher than they do in the adjoining territory. Between these points elevations of the beds are not available for the reason that they are not exposed at the surface. The area of elevated strata is probably about as that represented on the map (PI. I) within the limits of the 540-foot contour line. It is also a minor feature with unknown limits. In sec. 7, T. 1 N., R. 2 W. (Woodstock), and in secs. 10, 11, and 13, T. 1 N., R. 3 W. (Missouri)—that is, at Scott Mill—the St. Louis lime- THE AREA SOUTH OF THE COLMAR OIL FIELD 31 stone reaches an elevation 50 or 60 feet higher than it does to the south. Although elevations are not obtainable to the north, the limits of the elevated beds are probably correctly shown by the 570-foot contour line. Coal No. 2 lies at a higher elevation along what seems to be a small anticline whose axis runs southwest from sec. 5, T. 1 N., R. 3 W. (Missouri), through sec. 13, T. 1 N., R. 4 W. (Pea Ridge) ; but here also the rise is only a few feet. The coal bed also rises rather rapidly westward from 520 feet to 580 feet in sec. 4, T. 1 S., R. 3 W. (Mt. Sterling) ; but unfortunately lack of exposures and of field study makes it impossible to state now whether this bed continues to rise in this direction or culminates here in its highest observed point. In the area under discussion the greatest elevation which coal No. 2 attains is near the county line slightly north of west of Huntsville where the bed is more than 630 feet above sea level. The exact nature of this struc¬ ture is not clear, because the bed is concealed to the west. It seems probable that it is an elongate dome, although it may be a terrace from which the bed rises to the north or to the west, or in both directions. The structure is more pronouncedly revealed by the contours on the base of the St. Louis limestone which reaches its maximium height slightly to the northeast of that of coal No. 2. or along a curved line extending from secs. 34 and 35 northwest to sec. 17, T. 3 N., R. 4 W. (Birmingham). From the east the St. Louis rises rather rapidly from 530 or 540 feet to 580 or 590 feet along this belt of elevated beds. Unfortunately there are no outcrops to the west which would show the altitude of the limestone farther in this direction, but the suggestions are that the bed dips to the west, beyond the belt of elevated strata, thus forming an elongated dome. If on the contrary the limestone rises to the west then the structure is a terrace rather than an elongated dome. At any rate, there is a sudden arrest of the rapidly rising limestone along this belt of elevated strata and there is a terrace on the steeper portion of the dipping limestone two miles east of Huntsville as shown on Plate I. The Huntsville uplift is represented graphically on the map by contours based on both the limestone and coal elevations. RECOMMENDATIONS Because the oil-producing bed is lenticular and is absent over consider¬ able areas, the selection of favorable locations for drilling is fraught with more than the usual element of uncertaintv. There is little doubt that in some - of the areas described below, the sand is absent, and in this event there will be no accumulation of oil despite the favorable geological structure. It is hoped that the sand is present in at least a few of the areas listed below so that the combination of porous beds with favorable dips may be tested. The presence or absence of the sand cannot be predicted in advance of the drill. 32 OIL INVESTIGATIONS The general plan of prospecting here proposed recommends the drilling of the more pronounced domes and anticlines first. Further testing will then depend on (1) the presence or absence of the Hoing oil sand, and (2) if present, whether it is (a) dry, (b) contains oil, or (c) contains salt water (see figure 13 and discussion on pages 26-29). 1. Ordinarily the dome on top of the terrace-like area in parts of secs. 7, 8, 17, and 18, T. 3 N., R. 4 W. would be recommended for drilling. However, the Henry Pearson well in the NW. Ft sec. 19, which taps the Hoing sand horizon not more than 10 feet below the top of the dome, struck neither oil nor salt water. Wells in sec. 9, about one mile from the top of the dome and only slightly below it structurally, proved to be dry, and no salt water was found. A trace of oil was reported in the A. D. Lawton well in sec. 1, T. 3 N., R. 5 W. about 2 miles northwest of the dome mentioned. The Beard, Stark, and Gordon wells located from 2 to 4 miles southwest of the dome and structurally 25 to 30 feet lower showed neither oil nor salt water. Thus, the dome does not seem favorable. The only other location not tested is the top of the dome near the east side. A hole at the SW. cor. SE. 34 NW. Ft sec. 17, T. 3 N., R. 4 W. would test the oil horizon on the side of the dome from which the oil might have come. 2. In the shaded parts of secs. 26, 27, 34, 35, T. 3 N., R. 4 W. and secs. 2 and 3, T. 2 N., R. 4 W., as shown on the map, the beds lie approximately flat. They dip noticeably east, south, and north from this area. A well in the SE. cor. SW. Ft SW. 34 sec. 35, T. 3 N., R. 4 W. would test the sand on top of the terrace near its side where conditions are favorable for accumulation. 3. If the sand is present in the terrace mentioned under 2, and if it should prove devoid of oil and salt water as well, although sufficiently porous to hold these materials, it is suggested that a hole be drilled at the center of sec. 22, T. 3 N., R. 4 W. where the sand lies in a syncline and about 65 feet lower than in the top of the dome 2 miles northwest. It must be remembered that this test is not recommended until after the terrace described above is drilled. 4. The eastern end of a small terrace covers parts of secs. 14, 15, 22. 23, and 27, T. 3 N., R. 3 W. If the coal were present, its elevation would be about 596 on this terrace, about 35 feet lower than on the terrace described above. The beds dip north, east, and south, and although it N is not a large feature, the terrace seems to merit at least one test which might well be located in the NE. cor. SE. Ft sec. 22. T. 3 X., R. 3 W. There is considerable area to the east from which the oil might have been derived, and the flattening of the beds here is favorable for accumulation. 5. Outcrops at the east quarter corner of sec. 8 and in the NW. cor. sec. 21, T. 2 N., R. 2 W. (Buena Vista) show that the beds lie 20 or 30 ^ THE AREA SOUTH OF THE COLMAR OIL FIELD 33 feet higher than in the surrounding sections and probably show that a slight dome exists in the area shaded on the map, covering parts of secs. 4, 8, 9, 10, 16, 17, 20, and 21, T. 2 N., R. 2 W. A well in the center SW. y sec. 9, would test the highest part of the dome. The center of the SW. y sec. 16, would be an equally good location. 6. In the center of the SW. y NE. y sec. 13, T. 3 N., R. 2 W. the coal lies 590 feet above sea level, slightly higher than in the surrounding area. It is probable that the highest part of the arch lies /4 to ^4 mile northeast of this outcrop, or at the northeast corner of sec. 13. The beds have a slight dip in all directions from this point. In point of fact, this feature is scarcely more than a terrace southeast of which the beds dip toward a pronounced syncline. To the north and northwest in the Macomb quad¬ rangle the sand lies almost flat for 10 miles. A well near the NE. cor. sec. 13, T. 3 N., R. 2 W., would test the highest part of the low arch. 7. Outcrops in the northwest part of T. 1 N., R. 3 W. and in the north¬ east part of T. 1 N., R. 4 W. appear to reveal an anticline whose axis extends from about the center of sec. 5, T. 1 N., R. 3 W. southwest through the center of the west line of sec. 18. Field work has not been carried southwest of this point. Along the axis the beds lies 20 or 30 feet higher than at a distance of a mile or two on either side. If drilling is done along this anticline it is recommended that the wells be located slightly east of the axis as indicated. 8. In the area including parts of secs. 6, 7, and 8, T. 1 N., R. 2 W. and secs. 1, 11, 12, 13, and 14, T. 1 N., R. 3 W. the beds are arched into a dome. The dip on the south and east is greater than in other directions and can be seen without instrumental leveling in the valley of Crooked Creek. At the top of the dome the sand beds lie at least 50 feet higher than in the syncline which borders it on the southeast. North and west of the dome the dip is very gentle. Wells placed at the base of the blufif in the NW. y sec. 7, T. 1 N., R. 2 W. or in the SE. cor. sec. 12 would test the dome slightly east of the top where accumulation might reasonably be expected. 9. A flat, elongate dome separated from the one just described by a syncline, exists in parts of secs. 9, 10, 11, 14, 15, 16, 20, 21, 22, 23, 27, 28, 29, 32, and 33, T. 1 N., R. 2 W. Outcrops here are not as numerous as would be desirable, but they indicate that from the area shaded on the map the beds dip slightly in all directions. Structurally, the beds in this dome lie about 30 feet lower than in the area described immediately above. There is a considerable latitute for the selection of test wells in this dome but it is recommended that drilling be done first in the east half of the area shown by shading on the map. So far as structure is effective, wells in the SE. y sec. 28, SW. y sec. 22, and center of sec. 14, T. 1 N., R. 2 W. would be equally favorable. 34 OIL INVESTIGATIONS 10. Northwest of Frederick, in parts of secs. 6 and 7, T. 1 N., R. 1 E. and secs. 11 and 12, T. 1 N., R. 1 W., the beds lie flat; whereas east, south, and northeast there is a noticeable dip. Northwest of the area, exposures are lacking hut it is thought that the beds lie almost flat. Judging from structure and without any knowledge of the sand or salt water, there is a possibility of some accumulation along the outer edge of this terrace. So far as can be determined from the outcrops a well in the SW. *4 SW. J4 of sec. 7, T. 1 N., R. 1 E. would be located properly with regard to structure. If the normal oil-bearing horizon is barren of oil and salt water, it would be well to test the syncline which borders the terrace on the north¬ east and is outlined on the map by the 500-foot contour line. Whereas oil in synclines would be a new discovery for Illinois, it must be recognized that such accumulation is possible, and is well known elsewhere. 11. Along the north line of T. 1 S., R. 3 W., Brown County, the beds were found to rise noticeably toward the west, but field work was not con¬ tinued west of sec. 4 of this township where the coal lies 583 feet above sea level or 60 feet higher than at the northeast corner of the township. It is hoped that field mapping may be continued south and west during the sum¬ mer of 1915 to determine the position of the beds in that region. LOCALITIES ALREADY TESTED Of the wells drilled in the wild-cat territory to date, only two were located where the structure appears favorable. The Henry Pearson well near the center of sec. 19, T. 3 N., R. 4 W., (Birmingham), is near the high¬ est part of the dome northwest of Huntsville, and since it is dry, it is believed that this well discredits the dome, although it is not located at the most favorable part, namely, the eastern side of the dome as mentioned under No. 1 of “Recommendations.” A new well completed April 15 by Mr. H. E. Cary southwest of Rushville in the NE. At SW. J4 sec. 11, T. 1 N., R. 2 W. is located at the northeast side of a dome described under No. 9 of “Recommendations.” This well was drilled to 915 feet, which is about 75 feet below the top of the Trenton limestone. A small show of oil was noted near the top of the Trenton, but no mention of oil is made in the Niagaran at the horizon of the Hoing sand. A large amount of fresh water was found down to about 400 feet. Samples from the Trenton here show that it is not dol- omitic and that it would probably not be a good reservoir for oil. The well is not regarded as favorably located as if it were two miles southwest, near the crest of the flat dome. Table 1. — Drill holes in the area south of the Colmar field THE AREA SOUTH OF THE COLMAR OIL FIELD 35 1/3 Q* c a c n tc _I w 1—N rt (fl O £ 03 £ 4 —> Ts cn O £ on ^ O O d o QQ » >» >> >» lx U, ix ix t- u u U i— U lx QQQQQ QQ Q Q Q Q > ioo-hvOOC > • 00 > CM o > O CM lo co co > • CO > • CM • vo CK LO 00 LO VO On u-> M" CO CO CM o • o o >o K • vo o X o CM * »-' •v #v • •N X d co CO • O • CO . CM CM CM o VO . H H H H 1 H H d • • • • O d d d On d CM d • ^ • o • T-4 • • H • X . - • • o X! • o X • X X X • C/3 VO C/3 VO cn cn C/3 VO s c 3 3 3 3 £ . tJ- VO PO • i—( vo CM \Q \0 sO £ £ £ £ CM CM o o H o H • VO • VO O H 527 O H M - O H O H * cti c 3 3 D X 4X cn 3 1 ’ • 3 rt X r—H r—H 3 t—H D r r) '> o o 4-> txO bfl o 3 cn C/3 3 3 o rt 4-> T3 < • H e 1-4 u PQ o rv >» i-c ffi O O -M c PQ £ >> c 3 3 3 o 3 3 u -*—> O O X u o er . Beard . Stark . Gordo . Lawto >> XX 3 3 O U cn i- t_ c3 oS > 3 O U (-> CD lx CD >> s O U lx CD T, a •4—» m £ cs 3 3 O U lx d W TO o> -o o 2 ? 1 . j 3 U U ns • *—c w u 3 CD O rt i- 3 O 3 r~* •— u o o o x ct rt CD zz ►v_ • c/i pq PL, co _: Q Q r > ffi — — — — — — - - — • w > CO CO o vo G. Q. Q 1 Cn oc VO 1 rvj r-L ’ —' Cvl CvJ ^ — — — THE COLMAR OIL FIELD—A RESTUDY By William C. Morse and Fred H. Kay (In cooperation with the U. S. Geological Survey) OUTLINE PAGE Original study of region and prediction of oil. 38 Restudy of the field. 38 Beds penetrated in drilling. 39 Position and depth of oil-bearing bed. 40 Possibility of lower sands. 40 Position of Hoing sand above sea level. 40 Conditions governing accumulation in Colmar field. 42 Oil-bearing bed. 42 Erratic position of salt water. 43 Origin of the oil.•. 44 Extension of Colmar field. 44 Summary . 45 ILLUSTRATIONS PLATE PAGE II Map showing location of wells in secs. 9, 10, 15, and 16, T. 4 N., R. 4 W.. 38 III Map of Colchester and Macomb quadrangles including Colmar oil field.... 44 FIGURE 13. Cross-section showing the position of the oil sand in the Colmar field. 43 TABLES 2. List of wells in Colchester and Macomb quadrangles. 47 ( 37 ) ORIGINAL STUDY OF REGION AND PREDICTION OF OIL The Colchester and Macomb quadrangles, in which the Colmar oil field is located, were examined in 1912 by Llenry Hinds of the U. S. Geological Survey in cooperation with the State Geological Survey. In order to learn the position of the beds, Mr. Hinds determined the elevation of coal No. 2 above sea level at a large number of places and where the coal has been eroded, levels were run to outcrops of beds whose distance below the coal is known. His maps, published as Plate I, Extract from bulletin 23, State Geological Survey, May 1914, show a pronounced doming of the strata between Plymouth and Colmar, the highest part lying in secs. 19 and 20, T. 4 N., R. 4 W., where the coal would be 720 feet above sea level were it not eroded. The dip toward the east and south is greater than that toward the north and west. At the time of Mr. Hinds’ field work no wells had been drilled closer than 4 miles from the top of the dome, but the favorable nature of the structure led him to suggest the possibility of petroleum accumulation in the dome. He also mentioned the existence of a smaller dome in sections 29 and 30 north of Macomb. The following quotation is taken from his report: “Under those conditions (tilted beds saturated with salt water) accumulation takes place in the anticlines or arches or at the upper borders of dipping porous areas, (terraces [Editor]) where the porous rocks are at higher altitudes than in adjacent areas. A glance at the accompanying structure map will show that one such anti¬ cline lies two miles northeast of Plymouth only four miles northwest of well Xo. 4 near Birmingham. It is, perhaps, significant that the best reported showing of oil was in well No. 4, the one that is situated nearest the crest of this dome-shaped anti¬ cline, and it is unfortunate that at least one of the drillings was not made in the more promising territory. A similar but less pronounced dome exists near Macomb”. 1 RESTUDY OF THE FIELD Since the completion of Hinds’ report in 1912 and its publication in May 1914, nearly 180 wells have been drilled in the region, of which more than 130 located in secs. 9, 10, 15 and 16, T. 4 N., R. 4 \Y. are productive (see Plate II). Roberts No. 1 well sec. 24, T. 4 N., R. 5 \\ . and a new well on the J. M. Wear farm SE. J4 NW. 14 sec. 14, T. 4 NT R. 4 W. are, up to date, the only commercially productive wells brought in outside of the four sections mentioned above. The large amount of information made available by the drill rendered further study of the field desirable in order to determine (1) the position ’Hinds, Henry, Oil and gas in the Colchester and Macomb quadrangles: Ill. Geol. Survey Extract Bull. 23, pp. 11-13, 1914. ( 38 ) ILT T.4N. LAMOINE ILLINOIS STATE GEOLOGICAL SURVEY BULLETIN NO. 31, PLATE II THE COLMAR OIL FIELD 39 of the sand above sea level, (2) the relation of the position of the oil sand to that of the surface key rock, and (3) the conditions under which the oil accumulated. The additional field work by the senior author in 1914 consisted of the collection of drill records and instrumental leveling to determine the elevation of the wells above sea level. BEDS PENETRATED IN DRILLING Detailed descriptions of the formations are presented under the topic “Stratigraphy” in the first report of this bulletin. The following log of Griggsby No. 1 is presented, since it furnishes at a glance, knowledge regarding the beds down to and including a large part of the Trenton limestone. Most of the wells are drilled only to the normal oil-producing horizon at the base of the “second lime” as shown on the printed log. Records from the adjoining region are very similar to this one. except that from some places, especially east and south of the field, they show a greater thickness of material above the “first lime.” In the wells of the producing field the coal-bearing beds lying beneath the drift are almost entirely eroded; whereas farther east and south the “first lime” is found at a considerably greater depth and is overlain by shales, sandstones, and interbedded coals. Drill record of Griggsby No. i well, W. G SE. G T. 4 A 7 ., R. 4 W. Elevation above sea level 576 feet Thickness Depth Surface deposits Feei Feet Soil and clay... 25 26 Carboniferous system Mississippian series St. Louis and Osage groups Limestone, gray. Mud ... Limestone, white, sandy.. Limestone, gray, water at 115 feet.. , Limestone, white . Kinderhook and Upper Devonian shales “Lirst lime” Mud, white. Shale, brown . “Slate,” white, and mud. Shale, brown. “Slate,” white, and shale. Mud, white. “Slate,” white, sandy. Shale, brown. “Slate,” white, sandy.!'. Devonian and Silurian systems Limestone, gray, show of oil 425 to 432 feet, “Second lime” 10 10 44 55 35 30 10 40 10 20 21 67 7 15 34 36 46 90 145 180 210 220 260 270 290 311 378 385 400 434 40 OIL INVESTIGATIONS Ordovician system Ft. In. Richmond (Maquoketa) shale “Slate” and shale. 187 621 Kimmswick-Plattin (Trenton) limestone Limestone, white. 29 650 Limestone, brown. 155 805 POSITION AND DEPTH OF OIL SAND The Hoing oil sand was named from the first producing well in the field. It consists of well-rounded quartzitic grains and is lenticular in its occurrence. It lies on the Maquoketa shale, and at the base of the “second lime.” It is believed to have accumulated in the lower parts of the Maquo¬ keta surface and to have been reworked by the Niagaran sea. It repre¬ sents, therefore, the basal part of the Niagaran. In places it is overlain by Niagaran dolomite and where the latter is eroded it is capped by the Hamilton limestone. POSSIBILITY OF LOWER SANDS The only other horizon in the Colmar field in which oil might reasonably be sought is the Trenton limestone which lies 100 to 200 feet below the Hoing sand and is separated from it by shale. Samples of the Trenton from the region of Colmar show that it is a pure limestone and does not tend to be sufficiently porous to act as a reservoir for oil and gas. The odor of petroleum and a small show of oil have been noted in places near the top of the formation, but no accumulation has been found. The Trenton was penetrated 184 feet in Griggsby No. 1 and it may be as much as 400 feet thick. In order to test all possible oil-bearing beds, the Trenton should be penetrated by a few holes in each area where conditions are favorable. The St. Peter sandstone which underlies the Trenton, has never pro¬ duced oil in Illinois. When penetrated in central and southern Illinois, it generally yields an abundant supply of highly mineralized water. The amount of salts increases toward the south. o POSITION OF HOING OIL SAND ABOVE SEA LEVEL In order to show the parallelism between the beds outcroping at the surface and the oil sand, as well as the similarity in the folds affecting all of the beds down to and including the oil sand, Plate III has been prepared by printing in red, over the former map showing the position of the coal above sea level, a new set of contours which discloses the position and nature of the dome in the oil sand. The detailed structure of the oil sand, the determination of which is made possible by the drilling of a large number of wells in a small area, confirms in an extremely satisfactory manner the value of ascer- 3—B—31 THE COLMAR OIL FIELD 41 taining the structure of the outcropping beds prior to drilling. The crest of the dome, as shown by the coal and the St. Louis limestone, is identical in position with the apex as disclosed by the depth of the oil sand in the Collins well in the SE *4 sec. 20.. T. 4 N., R. 4 W. 42 OIL INVESTIGATIONS It must be remembered that most of the region is covered by glacial deposits; and on the surface, instead of being able to see the bed rock over a large area, the geologist is limited to scattered outcrops for his obser¬ vations, and it is to be expected that details of structure, such as terraces, may not be disclosed if outcrops are separated by considerable distances. Mr. Hinds’ coal contours and the contours on the oil sand by Mr. Morse, differ only in detail. The axis as shown by the sand extends east and west; whereas Mr. Hinds’ map pictures it as a line extending a few degrees north of west. Figure 13 us a cross-section showing the position of the oil sand along a line from the SW. cor. sec. 27, T. 4 N., R. 4 \Y. to a point a short distance south of the center of sec. 11, T. 4 X.. R. 4 W. Had the outcrops been as numerous and as closely spaced as are the oil wells in secs. 9, 10, 15, and 16, T. 4 N., R. 4 W. (Lamoine), the existence of the terrace would have been revealed in 1912. The beds at the top of the dome lie about 70 feet higher than on the terrace. No similar flat has thus far been disclosed by drilling in other parts of the Colmar dome. The beds dip away from the terrace in all directions except southwest. CONDITIONS GOVERNING ACCUMULATION IN THE COLMAR FIELD The accumulation of oil in the Colmar field, with the exception of Roberts No. 1 well mentioned later, is confined to the terrace on the north¬ east side of the dome. Most of the wells on the terrace reach the sand 85 to 95 feet above sea level. Griggsby No. 1 and Collins No. 1 located on the crest of the dome produced only a show of oil at elevations of 167 and 151 respectively; whereas Roberts No. 1, two miles west of the former wells had an initial daily production of 45 barrels from the Hoing sand at an elevation of 163 feet above sea level. However, the latter well is surrounded by dry holes and its production has declined rapidly to a few barrels. The striking differences in elevation between the oil in Roberts No. 1 and in the main field seem to be the result of (1) the nature of the oil¬ bearing bed and (2) the erratic position of the salt water. The second feature is probably due in large measure to the first. Oil-bearing Bed In the main field the oil sand has an average thickness of 14 feet. It ranges from 5 feet to more than 30 feet but in its greater thicknesses certain horizons are more productive than others. Outside of the producing field, many wells show no porous bed capable of holding oil; after passing through the “second lime” the drill penetrates blue shale which probably is the top of the Maquoketa shale. THE COLMAR OIL FIELD 43 The oil sand exists in lenses and is surrounded completely by im- previons beds, consequently it is natural for oil or salt water or both to exist in separated areas at different altitudes with barren areas between. Collins No. 1 and Griggsby No. 1 wells produced only a show of ('til and no salt water, but practically no porous beds were found at the base of the Hamilton limestone; whereas in Roberts No. 1, two miles west, 20 feet of porous beds are reported under the “second lime,” and the oil is found in the upper 10 feet. A short distance down dip from Roberts No. 1 these same porous beds are saturated with salt water. Erratic Position of Salt Water Salt water is found on the terrace from 10 to 15 feet below the top of the sand. A. N. Wear Nos. 2, 4, and 6 and many of the wells on the Thomas McFadden leases yielded salt water the first day and considerable oil thereafter. Most of the wells lower down the dip in the vicinity of the terrace contain salt water if the sand is present. South and west of the terrace and in the higher part of the dome salt water fills the sands in the vicinity of Roberts No. 1 well 40 to 70 feet higher than the salt water in the terrace. It is believed that the difference in elevation may be explained by the fact that the sand exists in two separated areas and that between the two the relatively non-porous limestone directly overlies the Maquoketa shale and the general result is an area of impervious strata separating two distinct lenses of porous, oil- and water-bearing beds. The conditions influencing accumulation, therefore, act independently in the two separated areas. It is believed that a small lens of oil sand exists in the vicinity of Roberts No. 1. Sometime after it had been covered by the overlying formations, oil and salt water, probably from the Trenton limestone below, migrated upward through the Maquoketa shale and found lodgment in the porous sands. As long as the beds lay flat, there was probably no definite rearrangement of the oil and salt water; but after the “Coal Measures” were deposited, folding began which finally resulted in the formation of the Colmar dome, the Lamoine terrace, and the other struc¬ tural features of the region. Rearrangement began immediately, the final position of the oil depend¬ ing on the proportion of oil and water in the porous material (see figure 13 and discussion). That the lens of oil-bearing sand at the Roberts wells is small is evidenced by the fact that the production of No. 1 has rapidly decreased from 45 barrels per day to only a few barrels, and there seems to be little hope of opening up a large production in the immediate vicinity. 44 OIL INVESTIGATIONS The general mechanics of accumulation in the producing terrace were the same as those outlined above. The larger amount of oil in the terrace is due probably to the fact that the mass of oil sand of which that on the terrace is only a part, must be very large, and after the folding of the beds took place the terrace, being the highest part of the lens, received all of the oil by virtue of the difference in specific gravity between oil and salt water, and the high degree of saturation of the sands. ORIGIN OF THE OIL No quantitative analysis of the organic material in the beds of western Illinois are available to furnish a basis for assigning the origin of the oil to any single formation. However, field examination in that part of the State has emphasized the oily character of the Trenton. The odor of petroleum is distinctly noticeable at most places on the outcrop and recent drilling in Schuyler County has disclosed the same characteristics. In many places the Trenton is composed largely of shells which give evidence of the enormous amount of organic matter originally in the formation. The “sweet” nature of the oil as mentioned in Extract from Bull. 23 has been a puzzling feature, since it is closely associated with limestones which generally produce the “sulphur” or “sour” oils. However, if the oil originated in the Trenton and finally found its way upward through the Maquoketa shales into the Niagaran, the sulphur would have been removed by filtration through the shale and “sweet” oil would result. Further work is necessary before the origin of the oil can be definitely assigned to the proper formation. EXTENSION OF COLMAR FIELD Up to date, practically the entire production has been from sec. 9, 10, 15, and 16, T. 4 N., R. 4 W. (Lamoine). Hartsook No. 1, NW. 34 SE. 34 sec. 14 contained no sand, but the bottom of the “second lime” which marks the top of the normal oil sand lies 90 feet above sea level or at the same elevation as the sand on the terrace one-half mile west. If the sand is present in any part of the SW. 34 sec. 14, it should contain oil. A good well has now been brought in by the Ohio Oil Co. in the SE. 34 NW. 34 sec. 14, about one-half mile east of the McFadden wells, and there is every reason to believe that much of the area inside of the 90-foot contour in sec. 14 as shown on Plate III will prove to be productive. The territory south and west of Colmar between the Bott well in the SW. 34 sec. 1, T. 4 N., R. 5 W. and the Roberts wells in sec. 24 of the same township has not been sufficiently prospected. Wells should be drilled in the S. 34 sec. 7 and the N. 34 sec. 18, T. 4 N., R. 4 W.; also in the S. 34 sec. 12 and the N. 34 sec. 13, T. 4 N., R. 5 W. The sand was not present in the Bott v r ell, but that fact does not condemn the territory mentioned. SURVEYED IN COOPERATION U. S. GEOLOGICAL SURVE GEORGE OTIS SMITH, DIREC IS STATE GEOLOGICAL SURVEY DUNNE, T. C. CHAMBERLIN, E. J. JAMES. COMMISSIONERS FRANK W. DE WOLF. DIRECTOR QA°45' ' TTTT3 ILLINOIS STATE G GOVERNOR E. F. DUNNE, T. C FRANK BULLETIN NO. 31, PLATE III Public roads Number* refer to elevation of surface above sea level ■***•’ Private roads ,‘"\f Approximate outcrop of Murpliysborn (No. a) cool ^ Shipping cool mine X Local coal mine ^ Stone quarry Clay pit ->■■■ _ > Loess—fine material between U a V clay and sand, unconsoli- a u o aJ dated, thicker along bluffs c J Q c C/5 .2 *G ’> o ■o Series c3 > 3 rj Ph c .2 "S Cu c u 2 J? > Drillers’ Interpretation o u in Formation Character Alluvium—mostly clay and sand; confined to the pres¬ ent valleys. Loess—fine material between clay and sand, unconsoli¬ dated, thicker along bluffs of larger streams, weathers into vertical cliffs; most conspicuous along west bluffs of Illinois River. Drift — mixed clay, sand, gravel, and bowlders, near surface on uplands. o to rt i o U v s Li • rt > in 2 o d rt l-M o CD £ CO 'O CD a «4-» o H: o 37 lo“ nO m- H—y rt Ui i_ D D H K._ _ S ^ ^ (X) co u D D D _ o ~ CO G lo rt 1 LO U »—< D LO rt rG £ o >3 03 t— o u * 4-1 o CJD rt o o O PQ s~ D bo rt d Pd O rt • ^h C o o o -*-> u Q i—i O f* L- Q D t -4 c r*\ 1—4 n Q rt tv u o o u <# c/3 o li PQ D W £ o H CO jajjenb pue •o x \j uopoae; w co I CO I <0 £ CO (•S[qq) uoij >» >> >> >3 LO >> >> -onpeud iBipuj Ah Q U Q V-. Q u n Ah Q Ah U Ah Q Ah Q M - Ah /“S Ah /-H Ah Q Ah Q •—1 (-• CT3 — 00 o M- o LO 00 LO M" On NO o o co co lO LO O • • O y —i y—i O' 00 CO A — LO SO 1-0 NO M- LT) LO M- M" M" co M" LO a pajBajauad LO a • H -G co LO LO 'Tf CO nO LO puss JO a CM • H • • • C/D • • • • CM ^-H --- T * V—* ss9u>piqj^ pp rC C/D > V) c > O r^O > o *H O' ~ C T—1 5> • • . H NO . . co 1^4 NO NO y—i ON cd -*-* 55 £ a\ • • • t^ LO nC • • NO M" LO LO M" O' 1) '+H . o H C/3 T -H ' T-H H prt o ^ M O H •> -*-c Gd 1-4 rt o CJ n . Os . rt CM O O . . o M" O LO *5 £ C/D o • cm • s LO 00 o • • 00 tv. nO y—> o7 1-0 c LO M* ~t LO CO co co M- LO bo rt U0I}BA9p G ffi CO < y-—i • • NO 00 T M - CM co LO o co y—\ aoej-ing Os • • OC CM co NO CO 1—< co Tf ~T CO O T—H LO m * »N >3 LO LO LO LO LO LO LO LO LO NO NO 4-» 4-» c G ^4 c t-H T—H r—H r' H r-H CM CO Tf ^4 ■ , G G G O O O g U O O pD Pd Pd Pd a a o O O o D V C D H u in r-j 1 >>22 rt ^ 'O ^ t/) 1— O a u ^ u os re £ ~ 4-. LO CO (•siqq) uop. o.ipojd [Bipu] Dry Dry Dry Dry Dry Dry Dry Dry Dry Dry Dry Dry 10 D ry 60 30 Prod Total depth • • • • 603 638 645 ip 1050 678 P 630 519 449 452 453 456 457 pajEjjauad pues JO ssauqatqj. ship 61 ownsh wnship wnshi 13 10 11 12 15 15 Elevation of top of sand Town -18 65 ter T 62? y To -44 (?) e To 51 57 66 80 87 88 85 Depth to sand ethel 612 437 olehes 540 ndustr 659 amoin 468 504 439 • • 434 424 424 429 PQ O M CM <0 \0 LO LO LO O M" > LO LO LO CM - o >> o LO o On lo '— 1 LO M 't O O ,-1 Md - - T-Ht^sOO—'LOO^—' >> LO LO LO LO LO LO LO LO LO LO LO r-t (M p t—H y—i f—H p r-H P p p p P p 0 0 0 0 O U O 0 jp i-H JZ bfl P f-2 "0 s i —i t— i n .. CM ce P o Q . u» £ £ X rt £ u _£ O M m -rtN CM P h4 in C -1 C >4.5 U ~ .2 2 7. m i be O 0 IS - 1 - 1 or co O o U c o o hJ >> Ih 4-> C/3 p T3 ►Spti £ o c u O * t3 o U O o o U -• CM T— H - — - - - - — - - jajjBnh puB & w w w W X CO CO CO CO CO CO CO CO •o^j uoipag 1 CM 1 0 1 1 r-H 1 co 1 1 CO 1 1 00 1 1 CO CM <0 CM CN) w £ £ 1 C\ m 1 Table 2.— Continued THE COLMAR OIL FIELD 49 Vi O > ?*■> r3 u~) ro ct5 03 03 4-> CM 4-» 03 C/5 r 4 ’o LO v—H u Uh LO rr* c/5 4-* a (w 3 £ £ -o u 4-> 4-> o 09 4—* » < » « ( Cw CO CO (•siqq) uop. onpojd jbi jiuj T3 "U 03 'll) 03 03 03 OOPPPPPPPCM CM Vi Vi Vh Vh Vi Vi Vi Ph Ph cl cl P—i Ph P-t 03 03 O O LO p O P O T OO CM 00 O CM —i Ph Ph 00 X) o Vi Oh Q ° vO o o o -H CM CM pajB-ijauad puBS jo ssouqoiqjL .2 qT .2 o- r T l O W £ V ■ h4 £ £ CP < a < Name of Company Ohio Oil Co. Do. J. E. Urschel & Co. Do. Do. Do. Do. Do. Do. Snowden Bros. & Co. HaMjo-o^ dEj\[ jajjBnb puB C/I •o^ uopoag 1 -B—31 o o o o Q Q Q Q o U o o o o o .2QQQQ js O o o o o o o Q Q C Q Q Q W £ 53 co I o Table 2 .—Continued 50 OIL INVESTIGATIONS C/2 re V (V (•S[qq) uotj -onpoad [Bijiuj On ■'T i O ON Vi o CO C/3 w J/3 *o3 4 -» C/3 C/J C/3 l-J t/3 C/3 j-* C/3 r j Cj ^ flj Gj U O C/3 ID Sh 0/ OC ^ ^ o 5 *_» «« Cw ,—, c/3 rtf s- O b £ U *0 v- rvj • * ;_ Os Ui WA W 5 C/D r- Tf to -*e _§ _^ J j£ “ r; o\ x -r t 7 X V- CO o rs v- cm r; 0/0 o < 4/ r« i_ c/3 c/3 c/3 ^ c/3 O V- > 4/0 0 < -'»oo Oooo b b J_ Vi Vi J_, Vi Vi ,_h Vi Vi p p pp p p p ^ ^ b o v- V- On OC O i—t VO lo ro 00 00 ■t K O LO LO LO On M" CN 'T lo y cm > .— .— — > 09 . . . o . "ID o • o« £ 6 o c 6 o o £ o ^ ' sj £ Q ^ o C~N .2 ON l—l W m —> >_„ 12 ; co i i M" co I [2 I u"> o c C/) 03 £ C 3 £ .5 4-> 4-» 4-> • r-H CO CO a >o ON 4" | 43 c -1 rt a 33 u C o re C/3 CC n-> CC •5 CO a (•S[qq) uoxj -onpoad ppm] 0 0 0 LO 0 O LO LO LO LO O 0 LO NO "d 0 0 43 O 43 0 43 0 43 0 LO 43 0 LO 43 O O 0 0 0 CM 0 O XM XO CM CM 1—4 Uh u u u dn U IM d- dn NO Oh PH Ph Ph Ph Ph Pp Ph 0 <0 CO NO CM O T —< ON Tt" LO NO O NO LO 00 O NO O 00 0 CO' On ^ Q 0 On t-H O O O t—H r—4 t-H T—H t—H ON x^ O 1— H CO 0 LO CO 4- M" nO CO On £ ^ LO 4" LO LO LO LO LO LO LO LO LO M" LO M" LO M" LO 4" 4" 4" 4" 4" 4- p9}E.xpu3d CM 00 NO NO LO <0 LO CM M" t—H 00 M" CM LO ■4- CM CO O On On puss JO SS3U>pXlJX r—H T—H t-H T— H t— H T-H T— H T— H T—H T—H t— H t-H T-H t—H .2 &T CM cm LO O v—H 1 —H ON CO ON r>. 0 NO ^1" CO LO LO "4" OO r-H LO CO NO nO j 1 Cu On ON On On ON On On 00 On 00 00 On CO CO ON 00 CO 00 ON CO On On CO On 00 O , "C5 ON t—H "Cf co NO t —4 CO 00 LO 4 - NO O CM NO 00 00 LO LO CM X>» XM 00 r-H LO O ,G H X^ CO 00 00 00 CO 00 00 00 00 00 NO <0 X^ LO NO ro X\ CM rO LO CM On c3 5 ;^ /“S 4" 4" 4" 4" 4" 4" 4" 4" 4" M" M" M" •Cf 4" M- M- 4- 4 - 4 - 4" 4- 4- 4- U0XJEA3P NO fO NO O0 NO CM 4 - 00 CO CO O 00 0 CO 0 ON CO LO 00 CO ON nO X^ X^ X^ X^ XM x^ NO NO ro NO 4- CM NO t-H CO <~o CM X^ <9 jtj. Jll ^ 10 LO LO LO LO LO LO LO LO LO LO LO 10 LO LO LO LO LO LO LO LO LO LO LO LO * * * * * * * * NO im CO ON CM ,— 1 <0 NO XM 00 ON ▼-H CM CO "4- LO ^H Ol CO t—H CM CO 4" y—t 5 T ” H r ~~‘ £ c "O r+ d > VrH rj c n H 5 c/5 O K P-i 4-h re (—1 W U '* 4—1 d U >> G. G c f) a % .0 ’0 O 0 0 O d O 0 d O 0 O 6 d O d d O > d d • i—i d 0 O u 0 <—• r -1 Q Q Q Q Q _o Q Q Q QQQQQQQQ rl Q Q pQDQ 0 rt hJ O 0 0 O c 5 hJ pMjo-o^[dej\[ japEnb puE •0|«J U0X}39g £ I c n 1 w co 1 Table 2 .—Continued 52 G4 (•siqq) uop -onpeuu xt* 14111 j p3}B.I}3U3d puns jo ssouqoiqx M C O .T3 . C* ■ rt UOIJBAOp ooBjang rt 0 O vo On co On OC t ^ sO co P O " co £ £* c- c C VO *- LTV o CM c o VO t ^ o o CM CM \ci s^r-j n«n ►— \ h\ hN, <—\ O < On ’—i'OvoOOCnvocoO’—'O vovO'—it^>.t^>.OONONCMOvj - c c ^- t t -r t x -t r c c c is m ci n ci ci ^ t *t VO tJ- ^ M" 'cF rj- tJ- -rj- tF tF M" r T vo M" rj- Tf Tl" ^ Tf Tt - ^ M" OC' co co On O On On \N cOi^OO( / 5 0\NNiOO'- < lNCiOO't 'OKONON^ooomooiO’tooT)- OnOCOnOOOnOnoOOOOOOnOnOOO OOcO'tKON'COCTC' ONOONOC'OOt^OCOCOOOC On CM vo 00 CM O ’— 1 "rt" '■t vo O vo cm vo sO co M" CM «— 1 On CM C CM 00 >—' OC OONKCMCMIMNCNInOco--I CM Tf VO O'— 0NjCM f M0 LO vo LO vo VO vo VO vo VO vo * * * CM co M- pA\J0-0£[ dEJ\[ UOIJOOg aajjBnb puB C /1 t-l 1 CMCMorvoOCM^rvoOO w ^ O! .53 O rn c/3 to c £ s J-H Far £ r-j —> 1 -* > o' u >» be c Cti _c a £ o a o r-> -o U c o *4-1 O o U 0>j r-t Ph o U c ’ w ,_■ £ c3 o # m . o 55 o o O o o O o p P P p p p p p .2 PPPPPPPQQQ o c n 0 O [[3MJO-OJVjdBJ\[ asjJBnb puB •ojq uoijoog w in i 54 OIL INVESTIGATIONS C> O CM W h-) w C H > r“ C3 o O O ■— c -> X o o o o _ _ £ £ co co 2 u _5 c/3 r5 CO ID M- o f3 r- — ONv00\O»-< lo a)\OoooO'00\coooioiAoo >o m- o -t- CO Tj- CM CM CC oc -r -r io M LO Cd ON ID CM O dx tx CM D O M- lo O O nO nO ^ O ID ID ID >D ID * * -5S- nO 00 On id lx X O O ID ID ID ID * * * 22 Tj- ID .2 o CG CM — W M ^ CO I w CO I o CM — CM CM ^M w ^ w & S C/3 ^ C/3 C/3 i i i i ro to O cnj c^i Table 2.— Continued THE COLMAR OIL FIELD 55 c/l t-l 6 O « RJ -t-> & lo¬ ll] ° j * —l v 03 > oi p £ O U M-i o O co CM ro M- i O ro M" O u o !> to 2 o co 5s o to tr^ rt u CD g <-M O o o G o § G +J a3 03 —H 73 -2 £ * co u •(—> 3n O 03 +H ~-n o*S t/2 ^ be - r“* C 3 G LO > tM 03 u ZJ -M U _• £ 03 X ^ S ffi >> >> Ih Ih Ih Ih Ih Ih Ih Ih Vh Q Q Q Q P Q Q Q Q X GO to a to ON a OOIkO^OOT 1 ^ 'COOO 1- '^OO^M nom- coox*-' X in X! to to to • . • # c • G • *— H (M * £ o £ O H Nf H oo o On > LO q-» NO Tj- LO to no no no to 4-» * * * * c T— H G i—' ■>— i ro i— ( t~i CM M" T— H s 3 o O O O X X be be 3 3 N O G > G ° c X > OJ O O • rH O O Uh r- o * X P o s u X £ Q o s g . H. Mo 03 o: '5 3 H « o o 03 23 ffi K M <5 ^ i C^^ o 6 U U if) C/3 a 03 o o 4-*' 6 — o* u U o U o X l-H -o Ih £ O o a n >* CJ O 3 o a '3 X r * 1 w-H o O u CO - - ; ; - — ~ CNI £ s & & & 5S CO C/I CO CO CO ^ CO O O 2 oil 0O Qs, in CD JC o > C CO CD > 0 ) > c CD > 0 ) > UJ CO > UI o 2 o £ > <£> CO -S' > UJ o 2 > tO S M > UI 5( -31 L2« -14 No nas or - water - a L5( Large gas vein mu Gas- Gas sand CM 6 I s C g «0 — > UJ o z JC o m' ^ CO > to si > UJ LEGEND Sand Sandstone Clay I * Clay and gravel Slate Shale Clay and Shale Sandy shaie Brown shale Black shale Rock Limestone Shelly limestone ii Fire clay Coal Good sand Salt water j£f Poor LUj sand Oil trace ILLINOIS STATE GEOLOGICAL SURVEY BULLETIN NO. 31, TLATE VII CM CO o <-> _ O) Oi > 5 © I > Ui I - > <£> Mo.3 'Oil' - 6 © cn = r^. § *5 o © 2 u © £ > CO o 00 > <*> ^ 10 > co © © > Ui 55 Gas trace •fit 1 ? Surlace Water Hard Light Red Flint No.6 Coal No. 4 Gray White Oil jock Oil ? --. . . Gas~ J trace Oil o d 2 rv. o 2 o CO o o © > o 00 CO o © > CM 00 cO 2 o © IT) CO 2 J* o V •<* o 2 jk o c © > > © Ui c co > > © UI > c <0 > CO > © UJ > c © > CO > © Ui © > c © > I 2 > CO |S > <£> > ur g £ 5 2 > UJ Gas LEGEND "Gas sand Gas Gas sand Gas ~ sand No.gas or - water ? Large gas vein n Gas Gas sand Good sand Salt water Poor sand Sand Sandstone Clay Clay and gravel Slate Shale Clay and Shale Sandy shale Brown shale Black shale Rock Limestone Shelly limestone Fire clay Coal m Oil trace Graphic sections of Litchfield wells (For location of wells see figure 17) OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES 89 and one-eighth mile wide. The gas holes, however, are sprinkled over a slightly wider area as may be seen from the accompanying sketch map (fig. 17). Plate VII shows the position of the oil and gas sands in the different holes. It will be seen that the gas wells lie chiefly to the east of the oil holes, and that the gas was reached in a sand which lies 40 or 50 feet higher than the oil sand. The distance between oil well No. 13 and gas well No. 5 is scarcely more than 500 feet, yet the gas sand is nearly R. 5 W. Fig. 17. Map showing location of wells in Litchfield pool and order of arrange¬ ment of logs in Plate VII. 50 feet higher than the oil sand as shown by the correlation lines on Plate VII. This is not easily accounted for, either by flexure or by faulting, since sharp displacements of the strata in so short a distance due to either of these causes are not known in this part of Illinois. The most plausible explanation of the phenomena lies in the probable presence of more than one sandstone bed, the upper of which was gas-bearing, whereas the lower was productive of oil. The fact that at the time the field was being 90 OIL INVESTIGATIONS exploited the gas was of more consequence than the oil and the fact that the first gas well was lost by the influx of salt water while drilling the hole deeper, offers an explanation of the failure to drill deeper in the eastern part of the field. No complete records of the early drilling have been preserved, and it is not now known whether the gas sand extended west¬ ward above the oil sand in the area of the earlier producing wells. This seems in some respects not unlikely since a gas-bearing sand is reported at the same horizon in the McWilliams well west of hole No. 13, though no upper gas sand was reported in the surviving fragmental logs of the oil holes. It is probable that the oil sand extends beneath the horizon of the gas sand in the eastern part of the field. In 1906 two new wells were drilled near the abandoned gas wells No. 5 and No. 15, both of which were reported to be oil bearing. Whether the holes reached the oil stratum below the exhausted gas sand, or whether oil during the 16 years since the exhaustion of the gas had found its way into the formerly gas-bearing horizon is not known. The wells were capped over without being pumped, and it seems probable, therefore, that but little oil was encountered. The productive sands in the Litchfield field, as well as in the Carlin- ville field, occur at and below the horizon of the Murphysboro (No. 2 ) coal. In the old Litchfield shaft where the first discovery was made, the oil sand lies below the horizon of the coal No. 1 and below the natural position of this coal in the McWilliams well No. 3. The sands from which the chief gas production has come seem to lie higher in the section and in the McWilliams well No. 3 this sand seems to lie at the elevation of coal No. 1 and probably cuts it out. The significant feature is that, although the sands are not continuous, the oil- and gas-bearing lenses correspond very closely in stratigraphic position to the oil and gas sands in the Carlinville area and were it not for intervening logs which clearly show the absence of this sand the beds might easily be correlated. In spite of the frequency of more or less extensive sand bodies higher in the Carbondale and McLeansboro formations no oil has ever been found in them, only pockets of gas being present. The conditions are somewhat analogous to those existing in the Carlinville field where, although the doming of the rocks appears to be the controlling factor in the accumulation of the oil, the character of the sand¬ stone lenses appears to have been the deciding factor in determining what particular part of the dome should be the repository of oil. The association of gas in a higher sand with oil in a lower, possibly connecting, bed is also a parallel circumstance. Only a few complete logs have been preserved so that a complete analysis of the field is now impossible. The field will never again reach its former production, but it seems possible on account of the high viscosity OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES 91 of the oil that considerable oil yet remains in the developed area, and that by drilling to the east of the old oil wells a modest production may be expected from the deeper sand. The viscosity of the oil preventing its easy extraction from the sands would seem to warrant the closer spacing of the holes and the use of modern devices for more complete extraction. The area has never received systematic development and though there is a possibility of future production on a small scale the returns will not be high. No information is available as to whether the holes were plugged, but it is probable that some were abandoned without plugging. What effect this may have had on the oil yet in the ground is problematical. Carlinville Oil and Gas Field The first knowledge of gas in the Carlinville area was obtained in the early sixties when a water well was being dug in the glacial drift in sec. 7, T. 9 N., R. 7 W. The man engaged in digging the well is said to have paused in his work to light his pipe, thus igniting a small pocket of gas, which the story relates set fire to his clothing. Led by this discovery, a well was drilled in 1867 near the east quarter corner of sec. 7; but the hole was unsuccessful, and prospecting was abandoned. In 1909 pros¬ pecting was renewed in the same area by the Impromptu Exploration Company, directed by Mr. T. A. Rinaker, and a small gas field was developed which was sufficient to provide illumination for Carlinville for two or three years. Continued exploration toward the east in November, 1911, developed a small oil pool which has had a reported production up to the close of 1914 of 16,540 barrels. An isolated gas well was drilled in the early part of 1912 on the Hammann farm near the center of the north line of sec. 16, T. 9 N., R. 7 W. The pressure is said to be between 85 and 90 pounds, but the owner was unable to come to terms with the Litch¬ field gas company and the well is now capped, and no effort is being made to use the product. The bottom of the well is 507 feet, below the surface and 295 feet below the top of the Herrin (No. 6) coal. The gas comes, therefore, from the lowest of the Pottsville sands recognized in this area. The gas in the Carlinville area was reported to be of good quality and similar to that at Greenville and Jacksonville. It is said to have been almost odorless and colorless, and to burn with a hot, blue flame. The initial pressure was 135 pounds but in 1912 it had fallen to about 35 pounds. The oil is dark brown and semi-viscous and has a specific gravity of 28.6° B. It is said to resemble the oil formerly produced in the old Litch¬ field pool and the Duncanville heavy oil of Crawford Company, though the former was considerably heavier than that found here. The structure of the oil- and gas-producing area at the horizon of the Herrin (No. 6) coal is a low dome crowning a long eastward-sloping surface having a dip of about 10 feet to the mile. The height of this dome 92 OIL INVESTIGATIONS does not exceed 20 feet at the horizon of the Herrin (Xo. 6) coal, but at the horizon of coal No. 3 and its accompanying limestone bed, and at the uppermost of the gas-bearing sands, the dome is accentuated as may be seen on Plate VIII. Figure 18 shows the dome by contour lines on the o O C/i U o u C/3 tc oc Herrin (No. 6) coal and on the highest sandstone bed. As may be seen, the deformation of the two surfaces is practically concentric. The Herrin (No. 6) coal bed has, however, not been reported in all the logs, and it has ILLINOIS STATE GEOLOGICAL SURVEY FEET 600 While White While fc While While IV5 Whllo Herrin or z £ i J > m Gas Gas Whllo Whllo Whllo Co 'I Gas Whllo m Brown While Whllo No.2 b 1 ( Murphy&boro Nq. 2 a j - - - Bi o\vn ? - - ISrny. Whllo Cool No.2 b X Whllo Soil wnlo'r' Dark CVof. While .Gas_ Brown White Water White Whllo White White Brown Whllo - . . No. 6 Gas' f&‘k...jL.... kp? ~G'as .. ..IJp-oii.--- .f No_2_a_ & Gray ■ - _ poa/ Graphic sections of Carlinville wells (For location of wells see figure 19) BULLETIN NO. 31, PLATE VIII •?- Strong gas' ‘ ~ Fine -P-DL, o Z £ . . Coil ? 3 Coal No.4 '<3ir - traco.,. r Brown - Whllo 12 .No,6 ’ ■ v •Sail Willow Brown No.2 m -» Gray While OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES 93 been necessary to determine its position in some of the wells by correlation of the logs on the overlying limestone and black shales. This may account for the apparent deviation. Whereas the doming of the rocks at this point was probably a very important factor in localizing the oil pool, other factors such as the slope, continuity, and porosity of the sand beds at different places were equally important. The discontinuity of the sandstone beds was recognized by F. H. Kay 7 who reported the field in 1912, but no attempt was made at that time to distinguish the productive sandstone lentils. Several new wells have been drilled in the past two or three years, and it now seems possible to distinguish four productive horizons only one of which, however, has been commercially profitable. Plate VIII shows the essential relations of the various sandstone horizons to one another. A little gas has been reported in several wells in the black shale immediately overlying the Herrin (No. 6) coal. The high¬ est gas-bearing stratum of any importance, however, was penetrated by the Klein No. 1 well, which passed into 30 feet of gas sand at a depth of 350 feet. The horizon of this sand is that of the upper bench of the Murphysboro or No. 2 coal, which, if no error has been introduced in reporting the log, has been replaced at this location by sand. The fact that no sand was reported at this position in either Denby No. 1 or V. Hall No. 1 wells one-half and one-fourth mile distant respectively, nor in any other log in the field except the Mutzbauer well in sec. 23, T. 9 N., R. 8 W. suggests either that the gas comes from an isolated sand lens, or that an error has crept in the log, and that its actual position is some¬ what deeper. The sand reported in the Mutzbauer well seems to substan¬ tiate the log of the Klein No. 1 well, at the same time suggesting a zone of sandstone lentils above the sands about to be described. The possibility of sharp flexure at this point seems to be discounted by the regularity of the sandstone below the Murphysboro (No. 2) coal and by limestone accom¬ panying coal No. 3 group. The next sand bed of interest lies 20 to 25 feet below the upper bench of the Murphysboro (No. 2) coal and is closely overlain by a bed of black shale, which may represent the lower part of the Murphysboro (No. 2) bed itself, this bed appearing in several of the logs in other parts of the quadrangles as a bifurcated seam. In the central part of the area this bed, which is gas-bearing at nearly every point penetrated, has a thickness of 6 to 8 feet with thin breaks enclosing, in one or two places, thin sheets of slightly oil-bearing sand. It thins toward the east and south, but even where no sand was reported the overlying black shale was found to contain some gas. 7 Kay, F. H., The Carlinville oil and gas field: Ill. Geol. Survey Bull. 20, 1912. 94 OIL INVESTIGATIONS In the Haake No. 1 well in sec. 17 a sandstone bed immediately underlies “black slate” at the horizon of the lower bench of the Murphys- boro (No. 2) coal. This is thought to represent in part a sandstone lens deposited in a channel cut down into a lower sand with the essential relations shown at A in figure 20. The sandstone reported in the V. Hall No. 1 well also probably represents a similar thickening of this sandstone, as does also the upper sand in Denby No. 1. This bed has been productive of* a moderate quantity of gas and a little oil, but the sandstone which lies just below has been more productive. The chief oil and gas horizon is commonly separated from the bed just described by 15 to 25 feet of shale. It lies at the horizon of coal No. 1 about 385 feet below the flood plain of Macoupin Creek and appears to lie in a channel cut into the beds somewhat later than the deposition of this coal. The reason for so regarding it, is that although this productive sand horizon is present in the wells drilled east of a general northeast- southwest line drawn between the V. Hall No. 3 and V. Hall No. 7 wells, it is absent to the west. In the Denby No. 1 well west of this line this part of the section contains coal No. 1, whereas in the V. Hall No. 3 well at the horizon of coal No. 1, black shale is reported. As black shale is frequently reported in place of this coal in wells in other parts of the district it is thought to be represented in this log. In the other holes west of this line either the interval is reported as shale, which is a conventional non-committal report in careless logs when no sand is present, or the interval is not reported at all. Whether the sand reported in the V. Hall No. 1 well is really an excessive thickening of the higher sand bed or whether it represents a protruding arm of the lower, more productive sand may be open to question, though the former appears most probable, from its stratigraphic relations. East of the line mentioned all of the holes which penetrate to this depth show sand at the position of coal No. 1. The chief producing bed is from 30 to 45 feet thick and is split into an upper gas-bearing sand and a lower oil-bearing sand by a break of shale 5 to 10 feet thick. If it were not for the fact that in the Hall No. 7 well these gas- and the oil-bearing horizons are in contact without am- intervening shale, the two sandstones might be considered as separate and distinct beds, as indeed they are in effect in most of the wells. It is probable that the shale parting between the beds is absent at other points and that communication from one to the other is thus facilitated, as sug¬ gested by the practical absence of oil from the upper bed and of gas from the lower. In the Anderson well one-half mile to the south of the producing wells, this sand is represented by one bed 27 feet thick lying, on account of the dip, somewhat lower than in that area. Here it is reported to be OIL AND GAS IN GILLESPIE ANI) MT. OLIVE QUADRANGLES 95 very fine grained and nearly dry. In the Freeman Hall No. 2 well drilled by the Impromptu Company only a thin, slightly oil-bearing sand is reported probably about the bottom of the lower part of this member. Adjacent parts of the section are not reported, but whether the sand is actually thicker than reported or not, the fact remains that the oil-bearing portion of this member appears to be present. As already stated the oil- and gas-bearing parts of this sandstone are in contact in the V. Hall No. 7 well without any intervening shale. Toward the west, however, a sudden change is to be noted between this well and the V. Hall No. 3 well, black shale replacing the sand in the latter. No sandstone was reported at the horizon in the log in the Freeman Hall No. 1 well of the Ohio Oil Com¬ pany, but as the producing member is reported in the Freeman Hall No. 2 well of the Impromptu Company, only a short distance east, a similar wedging out is thought to occur between these holes also. Still another and deeper sand is encountered below the chief producing sand. It lies about 25 feet below coal No. 1 and appears to be a more persistent and continuous layer than any of the others. It appears in the logs of all the wells in the field which have penetrated to this depth, but it has been found to contain chiefly salt water, though in a few instances, notably the Ohio Oil Company well on the Freeman Hall farm, the Best No. 1 well of the Impromptu Exploration Company, and others, traces of oil and small quantities of gas were observed. Its relations to the higher sands is shown in Plate VIII. Figure 19 shows the location of all the oil wells drilled in the district. It should be noted that the arrangement of oil and gas wells in the area has little significance since some of the holes report the condition of one sand bed and others of another. They therefore do not indicate any obvious relationship to the structural dome shown in figure 18. Plate VIII, though primarily designed to show the correlation of the sands, shows also in a rough way the structure of the area in cross-section, the logs being arranged as shown on the key map (fig. 19). Plate VIII is intended to show also that there is no one particular oil or gas sand, but that at and below the horizon of the Murphysboro (No. 2) coal there are present a number of sands any of which under favorable conditions is capable of receiving and retaining oil and gas; that the principal bed in which oil has been found is one which lies at the horizon of coal No. 1 ; that this bed is not a continuous sheet extending across the area like the coal beds and some of the limestones, but that it occupies what was origin¬ ally a broad shallow valley cut into the rocks not long (geologically speak¬ ing) after the formation of coal No. 1. This valley which no doubt had the usual irregular configuration of a shallow drain with more or less meandering course and subsidiary tribu¬ taries was later filled with silts of sand and mud of more or less varying 96 OIL INVESTIGATION’S a z u O u _) l/> i 1 * -