i ,C I- ^ : -*^ s&r^ R - L - LANGENHEIM, J \p }L i DEPT - GEOL. UNIV. ILLINOIS ^ . 254 N. H. B., J 301 W. GREEN ST URBANA, ILLINOIS 61801 Proas Bulletin Series T . ,., . Issued 1 wice Quarterly STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION A. M. SHELTON, Director DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON, Chief, Urbana No. 14 ILLINOIS PETROLEUM March n 1928 STRUCTURE AND OIL PROSPECTS OF EASTERN CLARK COUNTY By Gail F. Moulton and Jackson Young Introduction Following- the early development of the main eastern Illinois oil fields in 1906, 1907, 1908, and 1909, there was some haphazard drilling in eastern Clark County. J he various wells drilled at this time were mainly shallow only testing the possible oil-bearing formations to a depth of 1000 feet Although a deep well in Terre Haute, Indiana, had been producing oil from the upper part of the Devonian limestone for more than 20 years at that time other wells drilled nearby had resulted in failures, and the" operators in Illi- nois were not willing to spend the additional money required for deeper tests Fig 1. Index map There was considerable drilling i„ Clark County in 1925 and 1926 when ^operators were busy developing the proved deep producing area south- ron V n 7 e Pr ° dUCti0n had jUSt been discovered - the «PPer one of the Devonian limestone (call "Niagaran" and "Corniferous" by various drillers). By the end of the latter year very few undrilled locations remained, and interest in the area had practically disappeared. Late in 126 however, , well dn led in sec. 6, T. 9 N.. R. l0 W., Sullivan County, India a' -btamed a production of about 50 barrels per day of very light 'oil accom 2 ILLINOIS PETROLEUM panied by sufficient gas to cause the well to flow. The producing zone is in the upper part of the Devonian lime and was found at a depth of a little more than 2100 feet. The owners of the discovery well formed the Siosi Oil Corporation, and proceeded with the development of the remainder of the favorable acreage, which apparently was all under their control. Up to the present time about 15 wells have been completed which had reported initial productions ranging from 35 to 100 barrels. As a result of the discovery in Indiana, considerable interest was aroused in eastern Clark County, and at least two new wells were drilled in the hope of finding extensions of the Indiana pool. Geological conditions affecting oil accumulation in eastern Clark County have not been well understood, except in a very general way, because of lack of satisfactory data. The recent drilling has provided new data which per- mit a more accurate determination of structure and stratigraphy. It is the purpose of this report to make this new information available for the use of the oil operators. To that end a structure map has been prepared to show the configuration of the top of the Devonian limestone, a program of struc- ture drilling is herein recommended, and an area favorable for testing is described. The relation of the area described in this report to the main southeastern Illinois oil fields is shown in figure 1. Geology stratigraphy The general stratigraphic sequence typical of the region is well illus- trated by the cross-section accompanying this report (fig. 2). Additional details of the characteristic conditions in the eastern part of Clark County are given in the log of the Wernz well, sec. 22, T. 1 1 N., R. 11 W., which is published as part of this report because it is the deep well nearest the favor- able area. Driller's log from well on Wernz farm in sec. 22, T. 11 N., R. 11 W. Barometric elevation — 606 Feet Thickness Depth No. Feet Feet Pleistocene system 1. Soil, sandy 8 8 2. Gravel, brown, hard, fresh water Pennsylvanian system 3. Shale, green, soft 4. Sand, gray, hard, fresh water 5. Mud, blue, soft 6. Mud, green, soft 7. Red rock, red, soft 28 36 39 75 8 83 77 160 30 190 7 197 STRUCTURE AND (HI. PROSPECTS OF EASTERN CLARE COUNTY Driller's loy from well on Wcrnz farm in sec. 22, T. 11 N., R, 11 W. — Continued Barometric elevation — 606 Feet No. 8. Mud, blue, soft 9. Sand, gray, hard, dry 10. Lime, gray, hard 11. Slate, blue, soft 12. Shale, sandy, gray, hard 13. Coal, black, soft 14. Slate, gray, soft 15. Lime, gray, hard 16. Slate, gray, soft 17. Coal, black, soft 18. Lime, gray, hard 19. Shale, gray, soft 20. Lime, gray, hard 21. Coal, black, soft 22. Slate, blue, soft 23. Shale, gray, soft 24. Shale, black, soft 25. Slate, gray, soft 26. Sand, gray, hard, dry 27. Slate, gray, soft 28. Coal, black, soft 29. Slate, blue, soft 30. Slate, gray, soft 31. Lime, gray, hard 32. Sand, broken, gray, hard, dry 33. Slate, blue, soft 34. Slate, gray, soft 35. Lime, gray, hard 36. Slate, gray, soft 37. Sand, gray, hard ; salt water 38. Slate, blue, soft 39. Slate, gray, soft 40. Slate, blue, soft 41. Sand, gray, hard 42. Slate, blue, soft 43. Lime, sandy, gray, hard Mississippian (?) system Chester (?) series 44. Slate, blue, soft 45. Lime, shell, gray, hard 46. Slate, blue, soft 47. Lime, brown, hard 48. Slate, gray, soft Lower Mississippian system Lime series 49. Sand, gray, hard; salt water (probably lime) 50. Slate, blue, soft Thickness Depth Feet Feet 13 210 40 250 3 253 52 305 97 402 5 407 8 415 6 421 14 435 5 440 5 445 35 480 2 482 2 484 4 488 42 530 10 540 35 575 10 585 22 607 5 612 25 637 10 647 6 653 7 660 10 670 130 800 5 805 15 820 15 835 10 845 15 860 30 890 17 907 3 910 12 922 28 950 5 955 15 970 10 980 20 1000 50 1050 7 1057 ILLINOIS PETROLEUM Driller's log from well on Wernz farm in sec. 22, T. 11 N., R. 11 W. — Concluded Barometric elevation — 606 Feet No. 51. Sand, gray, hard; salt water (probably lime) 52. Slate, blue, soft 53. Lime, brown, hard 54. Sand, gray, hard 55. Slate, green, soft 56. Lime, white, hard 57. Lime, gray, very hard 58. Lime, brown, hard 59. Lime, gray, and white 60. Lime, brown 61. Lime, gray, broken, hard 62. Lime, gray, very hard 63. Lime, sandy, gray, very hard; salt water 64. Lime, gray, hard 65. Lime, white, hard 66. Lime, sandy, very hard; salt water 67. Lime, black, hard 68. Lime, slate break, black, hard Mississippian-Kinderhook shales 69. Slate, blue, soft 70. Shale, black, hard 71. Sand, gray, hard; salt water 1923 72. Shale, black, break 73. Sand, gray, hard; little salt water 74. Slate, black, hard 75. Slate, blue, soft 76. Sand, gray, hard; little salt water 77. Shale, black, hard 78. Lime, gray, hard 79. Slate, black, soft 80. Slate, blue, soft Devonian-Sweetland Creek shale 81. Lime, gray, hard 82. Shale, brown, soft Devonian-Onondaga lime 83. Lime, brown, hard 84. Lime, gray, hard 85. Sand, gray, hard; little salt water 86. Lime, gray, hard 87. Lime, sandy, gray, hard; little salt water 88. Sand, gray, very hard; full of salt water Casing record 12-inch set at 36 feet 10-inch set at 193 feet 8-inch set at 980 feet 6-inch set at 1650 feet Thickness Depth Feet Feet 28 1085 15 1100 10 1110 7 1117 3 1120 110 1230 35 1265 10 1275 45 1320 30 1350 30 1380 15 1395 40 1435 140 1575 20 1595 27 1622 103 1725 50 1775 30 1805 113 1918 52 1970 5 1975 15 1990 10 2000 15 2015 6 2021 42 2063 3 2066 19 2085 20 2105 8 2113 93 2206 14 2220 10 2230 5 2235 20 2255 19 2274 14 2288 STRUCTURE AND OIL PROSPECTS OF EASTERN* CLARK COUNTY 5 In general, the important changes in rock sequence which should be noted, as compared with conditions in the old fields in the western part of the county, are the greater thickness of both the Pennsylvania!! beds and the Fig. 2. Section showing stratigraphy and structure from the Martinsville pool to a well near Middletown, Indiana. (See fig. 3.) Mississippian lime, and the generally less sandy character of the Kinderhook shales. It is further to be noted that the interval from the top of the Missis- ILLINOIS PETROLEUM R. 14 W. R. 13 W. R. 12 W < O O O J s* R 14 W Fig. 3. Structure map of the top of the Devonian limestone in Claris STRUCTURE AM) OIL PROSPECTS OF EASTERN CLARK COUNTY R 10W. LEGEND Area recommended for testing Producing area Shallow dry hole Shallow dry hole pro- viding contouring data 'ounty and adjoining area, showing the locations of dry holes ILLINOIS PETKOLEUJI sippian lime to the top of the Devonian lime is fairly regular throughout the eastern part of Clark County and the adjacent portions of Indiana in- cluded in the structure map (fig. 3). The parallelism between these two contacts does not exist in western Clark County, and has only recently been known to exist in the area to the east. Apparently pre-Pennsylvanian erosion, which was so important farther west on the high part of the main anticlinal structure, did not affect the Mississippian lime series in the syncline to the east. Therefore, the structure of some of the upper beds in eastern Clark County can be used to a much greater extent than in western Clark County for determining the structure of the Devonian lime. For the present, data on the top of the Mississippian lime in eastern Clark County can be used with confidence for this purpose ; it is probable that further detailed work in certain areas in eastern Clark County will demonstrate the reliability of data on certain Pennsylvania!! beds for determining the presence of deep folding. A somewhat casual examination of available information on the lithol- ogy of the upper part of the Devonian lime, which includes the producing zone in the Martinsville and Siosi pools, shows that these beds are gener- ally more permeable north of Clark County, and are commonly tight and less permeable in southern Crawford County and in Lawrence County. The wells drilled in Indiana are believed to indicate a somewhat similar change from the southeast to the northwest and north. Although it is prob- able that the variations in permeability are related to an old erosion surface, the data thus far considered do not provide a basis for a definite statement regarding areas in which favorable permeability of the Devonian lime will be found, except that such favorable conditions are demonstrated by oil pro- duction at Terre Haute, the Siosi pool and the Martinsville pool. STRUCTURE The structure of Clark County, Illinois, and the adjoining part of Indiana is shown in figure 3 by contours drawn to give the elevation of the top of the Devonian limestone below sea level. Since all of the elevations are below sea level, the lowest structures in the area are indicated by con- tours having the largest minus elevations. The principal structural features of the area are the Westfield and Martinsville domes, the big dip to the east into the West Union syncline, and the rise to the east of this syncline into Indiana. The anticlinal nose in southern Vigo County, Indiana, where the present development is taking- place, and the anticlinal nose in Clark County, Illinois, near Marshall, are structural features which appear to be of lesser importance at the present time, but it should be observed that the data for these structures, particu- larly the latter, are very general and it is possible that the full extent of local domino- is not vet realized. STRUCTURE AND oil PROSPECTS OF EASTERN CLARK COUNTY 9 The structure of the Westfield area has been taken from a map in a detailed report now in press, 1 and the structure of the Martinsville pool from a map published in a previous number of Illinois Petroleum. 2 Except in the Siosi pool the wells which provided data used in contouring outside of these areas are indicated on the map by serial numbers which refer to their further identification in a table at the end of the report. The other wells shown on the map are reported to have been drilled in the locations shown, but no records giving data which could be used to determine geologic conditions are available. For most such wells only the approximate total depth is known. In preparing the structure map a contour interval of 100 feet is used because o\ the small scale of the map, the size of the structures mapped, and the considerable areas in which no data are available. Outside of the areas previously mapped the well elevations were determined by barometric methods, but the limits of error from this source are too small to introduce any important modification of the map. For most of the other maps recently published the Illinois Geologic Survey has used a contour interval of either 10 or 25 feet. In comparison with such maps the structures shown in figure 3 by the 100-foot contours do not appear as important as their relative size would indicate unless the difference in contour interval is kept in mind. The presence of an anticlinal nose or terrace near Marshall, Illinois, is one of the most important facts brought out by this investigation. Two ol the three wells which provided the data by which this structural feature was determined did not reach the Devonian limestone ; one of them did not even reach the Mississippian limestone, but correlations which seem to be clearly indicated by a comparison of the logs of these wells show that there is a locally high structure in the area outlined on the map. Available data do not permit a conclusion as to the size or exact location of this structure, but it is apparent that it is of sufficient size to merit testing for possible production in the Devonian limestone. RELATION OF OIL ACCUMULATION TO GEOLOGIC FEATURES A combination of local structure and regional permeabilitv within the producing zone determines the occurrence of commercially important pools of oil in the Devonian limestone. On the Westfield dome and on the Oak- land dome to the north in Edgar County, Illinois, the limestone was found to be so open and permeable that very little oil remained, even on the high parts of these big structures. In the Martinsville pool the producing zone 1 Mylius, L. A., Oil and gas in eastern Illinois: Illinois State Geol. Survey Bull. 54. PI. XXVI. (In press.) : Moulton, Gail P., Areas for further prospecting near the Martinsville Pool, Clark County: Illinois State Geol. Survey Illinois Petroleum No. 4, August 28, 1926. 10 ILLINOIS PETROLEU.M is almost too permeable to permit the accumulation of an important amount of oil, as is shown both by the abundance of water produced with it, and the low saline content of the water. In other parts of the area the permeability of the upper part of the Devonian lime is so restricted that its flow capacity is very small, and although oil accumulates in it, even on small structures, the rate of produc- tion is so slow that the wells are not profitable. The Riley pool in south- eastern Vigo County, Indiana, is an example of this type of condition. In areas with an intermediate permeability in the Devonian producing zone, wells drilled on favorable structures will consistently yield satisfactory production. The Siosi pool is believed to be typical of such favorable com- bination of conditions. The effect of structure in determining the producing area in the Mar- tinsville pool is very marked for the production from the Devonian lime. The boundaries of the producing area and the structure contours are closely parallel. Wells drilled high on the structure were characterized by their comparative freedom from water troubles. Successively lower wells on the structure had increasingly larger proportions of water to oil, until at the edge of the producing area the proportion of oil found was too small to make pumping profitable. A similar close relation between structure and the producing area seems to be indicated by the present development in the Siosi pool, and is to be expected for any other pools which may be discovered in the Devonian limestone. The uniformity of permeability is also important to oil producers because more uniform rates of production will be found over such a field than is usually true in the Illinois region for wells producing from sandstones. These considerations lead to the conclusion that oil producers desiring to develop production from the Devonian lime should first determine the location of large areas which appear to have suitable permeability in the producing zone of the Devonian limestone, and then should attempt to locate favorable structures in such an area. One area which is thought to meet both these requirements is described in this report. Although it is not believed that any rule of thumb method of determin- ing the proper permeability of the producing zone of the Devonian lime- stone can be given at present, it seems probable that mineral analyses of the water found in any wells drilled to this bed in the future should give a sub- stantial basis for comparing the effectiveness of water circulation through the zone at various points. The content of common salt, for example, in water from the Devonian lime producing zone in the Martinsville pool is only about half as great as that from the productive Mississippian lime above. On a basis of equal original salt content for the waters in these STRUCTURE AND OIL PROSPECTS OK EASTERN CLARK COUNTY 11 zones, it appears that the effectiveness of fluid movements through the De- vonian lime has been very much greater. Although the distance of an area from the point of inflow of fresh water, as well as the rate of movement of water, determines the amount of dilution of the original brines by waters percolating through the rocks later, it nevertheless seems probable that varia- tions in distance from the point of inflow over eastern Clark County are so small that they are of much less consequence than the permeability of the limestone in controlling the amount of dilution which has taken place. For the purposes of this report dilution of the salt content of the water is taken as directly due to the effectiveness of the permeability of the limestone in permitting fluid circulation. At the present time it is believed that only an exceptionally sharp struc- ture would be competent to cause oil accumulation in the Devonian lime- stone if it were more open than at Martinsville. We may proceed on this basis with the conclusion that areas in this district in which water from the upper zone of the Devonian limestone contain less than about 20,000 parts per million of sodium chloride (common salt), the amount present in the Martinsville pool, are to be regarded as unfavorable. A sodium chloride content in this general territory of from 20,000 to 30,000 parts per million is believed to indicate favorable conditions of permeability ; waters with a much larger salt content will probably be found only where the permeability of the upper part of the Devonian limestone is so reduced that the possi- bility of producing oil at a commercial rate is doubtful. Recommendations It is recommended that wells should be drilled to the top of the Missis- sippian lime in eastern Clark County to determine structural conditions which might be favorable for the accumulation of oil in the upper part of the Devonian limestone. During such structure-test drilling it is advisable to make an effort to detect characteristics of some of the Pennsylvanian forma- tions which may permit their use as key beds, should they prove to have a structure essentially parallel to that of the Mississippian limestone. It is recommended that the area shown as probably favorable on the map accompanying this report shall be the first locality tested by structure drilling, for a favorable structure is already indicated there and conditions of permeability in the Devonian limestone are believed to be favorable for satisfactory production. To start this program of development several structure test wells should be drilled in T. 11 N., R. 1 1 W. in the following locations and preferably in the following order: first, NE. J / A sec. 19; second. NW. % sec. IS; and third. XE. ]/ A sec. 20. The first well should serve to test the interpretation of structure based on the data available at present. If this interpretation is verified within moderate limits, the other 12 ILLINOIS PETROLEUM structure tests should be drilled for the purpose of determining the size and exact location of the favorable structure, as well as its highest part. Deep drilling then could be undertaken with considerable confidence, and the loca- tions should be chosen for the purpose of obtaining further structural in- formation as well as oil production, at least until several deep wells had been completed. If the first test shows that the interpretation of structure given in figure 3 is seriously in error, an immediate reconsideration of plans is advisable. A program of this sort is believed to be suitable for either a large pro- ducing organization, or for an association of smaller producers, for although the prospects of getting oil production appear to be fairly good, it is apparent that proper testing of this locality might require a larger expenditure than the usual Illinois wildcat proposition. The State Geological Survey will be glad to cooperate with any organ- ization desiring to undertake the testing of eastern Clark County, either in the favorable area described in this report, or in other localities which may appear favorable as a result of subsequent drilling. This cooperation will consist of furnishing any available detailed information from the files of the Survey, determining the elevations of wells, interpreting the data from the records of any wells drilled, and having chemical analyses made of the mineral content of water from the Devonian limestone from any wells located in that part of Illinois. Tables of wells, numbered for reference on map 1. Nattkemper and Connelly, NW. Vi sec. 11, T. 11 N., R. 10 W. a 2. Hodson, sec. 7, T. 11 N., R. 11 W. 3. Wernz, sec. 22, T. 11 N., R. 11 W. 4. Henbest, sec. 19, T. 11 N., R. 11 W. 5. Johnson or Cork? sec. 16, T. 11 N., R. 12 W. 6. Claypool, SW. % sec. 1, T. 11 N., R. 13 W. 7. J. Stout, NW. % sec. 26, T. 10 N., R. 10 W." 8. Tutt Mayfleld, SW. % sec. 4, T. 9 N., R. 10 W. ! ' 9. Welch Bros., sec. 11, T. 9 N., R. 11 W. 10. Beauchamp, sec. 4, T. 9 N., R. 12 W. 11. Golden, sec. 3, T. 11 N., R. 12 W. » Logs of these wells were obtained through the courtesy of the Indiana State Geological Survey, Dr. W. N. Logan, State Geologist, Bloomington, Indiana. The other records were obtained through the regular work of the Illinois Geological Survey. 11 (84363)