s 14.GS: CIR 470 G&oi Sl^r ttfy STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION HYDRODYNAMICS IN DEEP AQUIFERS OF THE ILLINOIS BASIN D. C. Bond ******* ILLINOIS STATE GEOLOGICAL SURVEY John C. Frye, Chief Urbana, IL 61801 CIRCULAR 470 1972 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/hydrodynamicsind470bond ILLINOIS GEOLOGICAL SURVEY, LIBRARY HYDRODYNAMICS IN DEEP AQUIFERS OF THE ILLINOIS BASIN D. C. Bond ABSTRACT Data on water levels, pressures, and water densi- ties in deep aquifers in and around the Illinois Basin were collected. In the northern third of Illinois water appears to flow from the west to the east. In the southern half of the state water appears to flow southward, but the evidence for such flow is of doubtful quality. In the north central part of the state the indicated directions of flow vary in a random fashion. The density of the water in these aquifers varies with depth and with location. Flow in such systems is quite complex; for example, differences in head can exist at the same elevation inside and outside a dome, even though no flow occurs. When flow does take place, it occurs princi- pally along the roof of the aquifer. Some net head is avail- able to cause vertical flow from the Mt . Simon Aquifer to higher aquifers; prior to modern pumpage this head probably was small. Some conclusions are presented concerning the effects of variations in water density in problems related to gas storage, oil accumulation, origin of brines, and un- derground waste disposal; for example, a tilted oil-water interface can be maintained with zero flow. INTRODUCTION Data on equilibrium water levels and hydrodynamic potentials in aquifers are of interest to many people. Petroleum reservoir engineers and geologists are concerned with the possibilities for the existence of "tilted water tables" under oil and gas accumulations. Researchers who study the primary accumulation of oil need to know something about the direction and rate of flow of water under- ground. Others, interested in theories about the source of natural brines, need information about the natural forces available for forcing water through semiper- 1 2 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 meable membranes, such as layers of shale. Gas-storage engineers need to know whether hydrodynamic gradients exist that will add to, or subtract from, the effective closure in proposed storage reservoirs. Hydrologists are interested in the natural potentials that may cause flow in fresh-water sources or in other aquifers. The present study was concerned with flow in deep aquifers in and around the Illinois Basin. Data on water levels and pressures in the aquifers, as well as on densities of the interstitial waters, were collected. For reasons to be given later, the head in terms of fresh water, H^'^O, was used, rather than the hydrodynamic potential, in efforts to interpret the results and to determine what flow, if any, occurred in and between the aquifers. With respect to flow, the study area can be considered in three parts. In the northern third of Illinois water appears to flow from the west to the east. In the southern half of the state water appears to flow southward, but the evi- dence for such flow is of doubtful quality. In the north central part of the state the indicated directions of flow vary in a random fashion. The density of the water in these aquifers varies with depth and with location. Flow in such systems is quite complex, as shown by a listing of some of the parameters that influence flow. A possible explanation of the indicated random flow in the northern part of the basin is presented. Finally, consideration of the effects of variations in water density in aquifers leads to some important conclusions about problems related to gas stor- age, oil accumulation, origin of brines, and underground waste disposal. Acknowledgments The cooperation of the following is gratefully acknowledged: T. W. Anger- man, Huntley and Huntley, Inc.; S. J. Bateman, Halliburton Co.; Leroy E. Becker, Indiana Geological Survey; J. H. Buehner, Marathon Oil Co.; R. J. Burgess, Con- sumers Power Co.; Peter Burnett, Consultant; C. V, Crow, Illinois Power Co.; R. G. Davidson, Johnston Testers; T. A. Dawson, Indiana Geological Survey; G. E. Eddy, Michigan Dept. of Natural Resources; G. C. Egelson, Dow Chemical Co.; G. D. Ells, Michigan Dept. of Natural Resources; R. H. Fulton, Mississippi River Transmission Corp.; C. M. Gadd, Humble Oil & Refining Co.; R. C. Clausing Panhandle Eastern Pipeline Co.; Lloyd A. Harris; Dan Hartman, Midwest Steel Corp.; F. W. Hunter, Northern Illinois Gas Co.; G. S. Keen, Northern Illinois Gas Co.; N. C. Knapp, Mobil Oil Corp.; K. R. Larson, Peoples Gas Light & Coke Co.; R. C. Magenheimer, Northern Illinois Gas Co.; Richard K. Meyers, Cheme- tron Corp.; D. A. Miller, Phillips Petroleum Co.; R. R. Miller, Northern Natural Gas Co.; J. M. Montgomery, Halliburton Co.; Felix C. Moody, Halliburton Co.; C. C. Olsen, Halliburton Co.; K. W. Robertson, Illinois Power Co.; G. L. Royce, Northern Illinois Gas Co.; W. M. Rzerpczynski, Natural Gas Pipeline Co. of America; Neil Schemehorn, Northern Indiana Public Service Co.; J. L. Skilfield, Superior Oil Co.; L. H. Smith, Union Oil Co. of Calif.; andT. C. Buschbach, Keros Cartwright, T. L. Chamberlin, Paul Heigold, R. F. Mast, and W. F. Meents, Illinois State Geological Survey. HYDRODYNAMICS IN DEEP AQUIFERS 3 Nomenclature and Definitions H bs. ~ observed head, with respect to sea level, feet jjl .00 _ h ea d i n terms of fresh water, with respect to sea level, feet L obs. = length of observed water column, feet L eQ = length of equivalent fresh-water column, feet p = density of interstitial water, relative to fresh water P es i = relative density estimated from plot of p versus total dissolved solids in water Z = elevation with respect to sea level, feet AZ C = thickness of cap rock, feet P 1 t a - [AH 1 - 00 - / (P- 1) dZ] where AH*- 00 - (H^°°- hJ" 00 ). H^ 00 r Po Z 1 1 and H 2 ' are the values of H * at points P^ and Pp respectively. J ( P — 1) dZ is the integral along a flow path from ?2 to p l • P 2 fp. = AH 1 ,0 ° — {p jl — 1 .00) AZ; p i = value of p at point ? i in the aquifer Vave. =AHl " 00 " iP ™e. ~ * ■ °<» ^ ^ave. =

= potential, feet, relative to sea level S. L. = sea level ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 Summary of Previous Conclusions About Flow in Aquifers That Contain Water of Variable Density* M. K. Hubbert' s classical papers on the flow of ground water were published in 1940 and 1953, Since then many people have applied Hubbert' s concepts to a variety of problems, including entrapment of oil, underground storage of gas, and flow of ground water. Although Hubbert' s original ideas have been extended into many areas of investigation, one important problem still needs some study and clarification: the problem of determining the direction and rate of flow of underground waters whose density varies from point to point because of changes in the concentra- tions of dissolved solids . McNeal (1965) touches upon this problem. In a personal communication (1969), he gives a procedure for correcting potentiometric surface maps in basins where water density varies; a pressure correction, AP , is subtracted from recorded u S pressures, where AP = 2 0.433 (p _ p _ ) AZ, s ' sw fw and/O sw and yo f w are specific gravities of salt water and fresh water, respectively, and AZ is the vertical distance over which each type of water exists. Hitchon (1969a) says, "Flow in variable density water systems, such as exist in most sedimentary basins, may be empirically represented by using a standard density." He describes a method that involves dividing an area into discrete density regions. Using a best-value density, hydraulic-head maps are made for each region and flow lines are constructed within each region. If there is no opposed flow between any two regions of differing densities, it may be con- cluded that the flow paths can be empirically represented by using a standard density throughout the system (Hitchon, 1969b). Hanshaw and Hill (196 9) say, "One can attempt to correct all the po- tentiometric data for salinity variations, but this is a difficult task. Not only must one correct for the density of water in the aquifer at the well site, but one must also consider the integrated density of all water in that aquifer which is at higher points on the potentiometric surface. " These authors do not give the basis for their statements about density corrections. The derivation of their pressure corrections needs to be outlined. Terms such as "integrated density" need to be defined, and the implications of density effects with respect to possibilities for flow need to be clarified. Hubbert (1953, p. 1995) discusses the problem briefly. In particular, he shows how to handle the case of a basin in which the salinity of the water increases with depth. Pressure and density measurements are taken in a row of wells extending down dip from the flank of the basin. A well in the middle of the row is used as a reference well; the density of the water in this well is used as a reference density. At each of the wells, the potential of the water having the reference density is calculated, using this density and the pressure measured in the well. The plot of potential versus distance shows whether the water is static (minimum in curve) or flowing (direction of flow is tangent to curve) . This treatment appears to be valid for the idealized case in which the basin is assumed to consist of a set of perfect saucers, with no sharp changes in rii i Ls I tkeri partly From "Pressure Observations and Water Densities in Aquifers and Their R< Latlon to Problems in Gas Storage" by D. C. Bond and Keros Cartwritfht, 1970, Jour in j '>r Petroleum '\'<->\<>r.:/ , v. X/JI , |». I'l'J-' I'I'Jo. M:i.t<«r.i:i.l .from that article used in this Circ I Minted with the permlsi I f the Journal of Petroleum '1'cchnoJ o^y . HYDRODYNAMICS IN DEEP AQUIFERS 5 salinity with distance and no barriers to impede flow. It may have limited appli- cation to a real basin. It has been shown that a trough containing dense water can serve as a barrier to flow. In an area where salinity is changing rapidly, where waters are stratified, and where structural troughs exist, Hubbert' s method may not apply (Bond and Cartwright, 1970). Lusczynski (1961) studied systems in which fresh water and sea water moved through an aquifer under the influence of gravity near sea level. He de- fined "point-water head" at a point as the water level, referred to sea level, in a well filled with enough water of the type that exists at the point to balance the existing pressure at the point. For such systems "point-water head" is equivalent to Hubbert' s "potential. " Lusczynski introduced the concept of "environmental- water head, " which he defined thus: "Environmental-water head at a given point in ground water of variable density is defined as a fresh-water head reduced by an amount corresponding to the difference of salt mass in fresh water and that in the environmental water between that point and the top of the zone of saturation. " He used a quantity, p a> which is the average density of water between sea level and the point of investigation. Equations were deduced involving point-water head, environmental-water head, and p a ; these equations appear to be useful in deducing information about direction and rate of flow (Lusczynski, 1961, p. 4249-4250). Lusczynski' s conclusions appear to be valid and useful for the relatively simple systems that he studied. In deep, high-pressure aquifers his conclusions will be difficult to apply. In such aquifers it may be difficult, if not impossible, to determine accurately the density of the interstitial water at one point, let alone at a series of points at various levels in a well. Lusczynski' s method appears to be valid only when the aquifer extends from the surface downward to the zone of investigation; in general, deep, high-pressure aquifers are isola- ted from the surface by impermeable rocks. Also, as shown by Bond and Cart- wright (1970), troughs and "corrugations" in flow paths in variable-density systems can influence flow greatly. Only in rare cases will the geometry of the possible flow paths and the density of the water be known in enough detail to permit a treatment like that of Lusczynski. Flow through aquifers containing water of variable density was studied by Bond and Cartwright (1970). In order to avoid ambiguity about the implications of potential in such systems, they used hydrostatic head rather than potential. Following are some of their conclusions: 1. In an aquifer containing water whose density varies from point to point because of changes in the concentrations of dissolved solids, knowledge of the hydrostatic head at two points does not necessarily enable one to determine the direction of flow, if any, between the two points . 2. In general, no flow occurs along a given flow path if P l AH 1 * 00 =/ (p- 1.00) dZ. A trough filled with dense water can serve as a barrier to flow. ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 3 . Where waters are stratified in an aquifer according to their density, the "potential" of a well has no unique value; instead, the potential (or the head) at a point in the well or in the aquifer should be considered. In such a variable-density aquifer, differences in observed head do not necessarily indicate flow through the aquifer, even though the produced waters from different wells in the aquifer have similar densities. 4 . Water flows upward through conduits in a cap rock if (h1- 00 -h^ 00 )>(/> 2 -i.oo)az c . Water flows downward if (H 1.00_ H 1.00 } < (/?i _ 1 .oo)AZ c . No flow occurs (static interface exists between the two waters within the cap rock) when ( y o 1 -l)AZ c < (H2-°°-Hi- 00 ) < (/> 2 _1)AZ C . That is, the interface acts like a valve which prevents flow through any conduit that may exist in the cap rock. The distance, AZ eq , from the bottom of the cap rock to the equilibrium interface is given by AZ eq . =[H2-°°-h}- 00 - ( Pl _ 1. 00) AZ Q ] /( P 2 ~p^ (Here Hi ' and H2 ' are the values of H at the top and the bottom of the cap rock, respectively; p -, and p 2 are the relative densities of the waters in the aquifers above and below the cap rock, respectively, and AZ C is the thick- ness of the cap rock.) HYDRODYNAMICS IN DEEP AQUIFERS OF THE ILLINOIS BASIN The present report summarizes the available pertinent information on water levels, water densities, reservoir pressures, and hydrodynamic potentials in the deeper rock strata (St. Peter Sandstone and deeper, fig. 1), in Illinois and parts of Indiana, Michigan, and Iowa. Information from these sources was used: 1. Drill-stem tests in drill holes (oil and gas tests, gas- storage wells, waste-disposal wells); 2. Equilibrium reservoir pressures measured in wells; 3. Virgin equilibrium water levels in wells, principally in gas-storage reservoirs. This material was obtained from the files of the Illinois State Geological Survey and from individuals and companies listed in the acknowledgments. Much valuable information was also taken from testimony and exhibits filed with the Illinois Commerce Commission in hearings concerning proposed underground gas- storage projects . HYDRODYNAMICS IN DEEP AQUIFERS LITHOLOGY Shale, red, hematitic, oolitic Shale, dolomitic, greenish gray Dolomite and limestone, coarse grained; \shale, green Shale, dolomitic, brownish gray Dolomite, buff, medium grained Dolomite, buff, red speckled Dolomite and limestone, buff Dolomite and limestone, gray mottling Dolomite and limestone, orange speckled Dolomite, brown, fine grained Sandstone and dolomite Sandstone, fine, rubble a1 base Dolomite, sandy Sandstone, dolomitic Dolomite, slightly sandy; oolitic chert Sandstone, dolomitic Dolomite, sandy; oolitic chert Dolomite, slightly sandy at top and base, light gray to light brown; geodic quartz Sandstone, dolomite and shale, glauconitic Sandstone, medium grained, dolomitic in part Sandstone, fine grained Siltstone, shale, dolomite, sandstone, glauconite Sandstone, fine to coarse grained Fig 1 - Generalized columnar section of Cambrian and Ord eastern Illinois (from Buschbach and Bond, 1967, ovician strata in north- p. 21). 8 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 Procedure Data taken in relatively deep drill holes were tabulated (tables 1, 2, and 3, appendix 2). Pertinent available information about all holes drilled to the St. Peter or deeper well within the Illinois Basin was included. Data on relatively shallow wells around the rim of the basin were not included. The information that was collected included: (1) Surface elevation (2) Depth to top of aquifer investigated (3) Depth to top of perforated zone (4) Total dissolved solids and specific gravity of water samples recovered by swabbing or by pumping or in drill-stem tests (5) Equilibrium water-level observations in wells (6) Drill-stem test (DST) results (a) Gauge depth, top and bottom gauge (b) Initial and final closed-in pressures (c) Pressure extrapolated to shut-in time, 6 , = °o (d) Liquid fill-up during DST. In tables 1, 2, and 3, column 10, the heading "observation point" needs a word of explanation. Generally we can calculate H**00 for only a few points in a well. The observation point may be the position of the drill-stem test pressure gauge, the reservoir pressure gauge, the top of the perforations in the casing, or the top of the open hole (casing seat). In some cases, for lack of better in- formation, the observation point was taken to be the top of the DST interval or the top of the aquifer. The quality of the data varied from very good to very poor. Generally data from all sources were tabulated; then, if reason existed for choosing one value in preference to another, a judgment was made about the value to be used. For example, a water level, carefully taken, was better than a drill-stem test result, especially if the rock had limited permeability. A water sample taken after extensive swabbing or pumping was better than a sample taken in a drill- stem test. However, all choices were not as clear cut as this. For example, sometimes a choice had to be made between the results of a relatively poor drill- stem test and the results of a water-level observation taken in a hole filled with water whose density was not known accurately. The accuracy of well-head elevations was checked against topographic maps, well-log records, and other sources. In particular, an effort was made to insure that, for a given drill hole, the values used for depth of the water level, observation point in the aquifer, and depth of the pressure bomb were all measured with respect to the same elevation. Calculation of H The most significant quantity in this study is H , the head in terms of fresh water, with respect to sea level. When we say that H* • 00 has a given value, N, at an observation point, we mean that in a manometer tube containing water having a relative density of 1.00 and open at the observation point, the water would be in equilibrium with the water in the aquifer if the surface of the water in the manometer tube was at a level N feet above sea level. The pro- cedures used in calculating H 1 *^ are given in appendix 1. HYDRODYNAMICS IN DEEP AQUIFERS 9 Results The present study gives information for about fifty locations in Illinois, central and eastern Iowa, southwestern Michigan, and northwestern Indiana. In- cluded are data from about 20 gas-storage projects and 25 miscellaneous drill holes: oil and gas tests, holes drilled for gas-storage projects, and waste- disposal wells. Most of the observation points were more than 1,500 feet deep and ranged down to almost 12,000 feet deep (tables 1, 2, and 3). In many gas-storage reservoirs, data are available for a number of wells. In tables 1, 2, and 3 usually data for only one well in each reservoir are listed; the well is generally the one that appears to be representative of the reservoir or the well for which the most complete information is available. In a few cases, averages or reasonable estimates are given. Because of the importance of Royal Center, to be explained later, most of the available data for that reservoir are presented in the tables. The data on subsea depths, water levels, pressures, and water densities, as well as the derived values of H-"-*^, can be presented in various ways. Fig- ures 2, 3, and 4 show how subsea depth, water density, and h^- u ^ vary from one location to another. Figures 5, 6, 7, and 8 are cross sections that show how these quantities vary as we go into or across the Illinois Basin. In a general way, as we go from the northern part of Illinois toward the deeper part of the Illinois Basin, the values of H^-CO in a given aquifer increase. The increase in H • Ul ^ is more pronounced for the Mt. Simon than for the Ironton- Galesville or the St. Peter. If the densities of these waters were uniform, we could conclude immediately that water flows toward the north from the deeper part of the basin. But the densities of the waters, rather than being uniform, increase steadily southward, more or less paralleling the increasing values of H • u . Furthermore, evidence exists that at a given location the density of the water may be a function of depth. In a system like this, flow is not a simple function of hydrodynamic potential or of hydraulic head, but it depends upon many factors, as will be shown in the following section. Some Factors That Affect Flow This study was undertaken primarily to determine what flow, if any, occurs in the deep aquifers of the Illinois Basin. Flow in systems like these is complicated by many factors. Before we attempt to interpret the data on water levels, water densities, and pressures, we need to review some of the parameters that affect flow in such aquifers . Potential . — In a system that contains water of uniform density , Hubbert 1 s potential, cj>, can be used to determine whether flow occurs. The rate of flow is a function of potential, permeability of rock, and viscosity of water, as shown by Hubbert (1953) . On the other hand, in a system that contains water of variable density , only in certain simplified situations can the potential be used to de- termine whether flow occurs . Hubbert' s treatment assumes that no mechanical barriers to flow exist in the region under consideration. But a trough filled with dense water can be a barrier to flow; a number of small troughs in series can be just as effective a barrier as one large one. Potential can be used to make inferences about flow only if the effects of such troughs are known to be negligible. 10 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 Hydraulic head . — In general, for a system that contains water of vari- able density, flow can occur along a given flow path if , p l [AH 1 .00 J' < p 1) dZ] along the flow path is not zero. The direction of flow depends on the sign of the quantity f p . The magnitude of this quantity is a measure of the net force avail- able to cause flow (Bond and Cartwright, 19 70). In the case of flow paths for which Z is constant, the criteria for flow are simplified; for such flow paths, a difference in head between two points is proof of flow between the points. Over an area that has no barriers to flow, at elevation Z, the head and the water den- sity at this elevation are constant when the water is static. Consider an aquifer in which H^ -00 and p vary from point to point: The force available to cause flow from ?l to P2 is proportional to [AH 1 .00 1, 2 a / a (/> - 1) dZ]. This force is a component of the total force vector acting on water along a line from P^ to P2 a * The general direction of flow may be from Pj_ toward P 2 , that is, from left to right . But the true direction of flow will be along the line where [ AH — S ( P — 1) dZ] is at a maximum. If p and AH are known in detail, flow patterns over the area can be deduced. Generally p and AH are not known in de- tail; therefore, true flow patterns can be deduced only if simplifying assumptions are made. Mixing zone. — Considerable mixing occurs when one water in an aqui- fer is displaced by another (Ogata, 1970). In the area studied, this mixing ap- pears to have resulted in appreciable changes in composition and density of water within relatively small distances. The entire mixing zone appears to be about 50 to 100 miles wide. Tilted interface . — Hubbert (1953, p. 1994) has shown that when fresh water flows above salt water in an aquifer, the interface between the two is tilted. When stratified water of variable density flows through an aquifer, it can be considered to have an infinite number of such tilted interfaces in which the angle of tilt decreases with depth. Flow of light water along roof of aquifer . — Consider the simple case where the roof of the aquifer is flat and fresh water displaces water having a relative density p. Let AH 1 -00 be the difference be- tween values of Hi -00 at locations W} and W 2 at the top of the aqui- fer. Let h be depth measured from Roof of aquifer w i W ? 1 > r J> fresh water .x- Dense h r wat r (Vertical scale is greatly exaggerated.) HYDRODYNAMICS IN DEEP AQUIFERS 11 VINCENT (CENTRAL IOWA) -1016 1.009 924 REDFIELD ( CENTRAL IOWA) CAIRO,! COLUMBUS G.ITY, WAPELLO ~-l650 1.007 677 'ECATONICA 1.00 ■ 686 (EC) ;ville«ioo 1.00 648 652 (EC) WEST CHICAGO -l545to-3644 1.04 (EC 8MS) -1010 418 (EC) -1187 400 (EC) -2801 468 -1585 to -3667 1.048 — '— (EC 8 MS) V LOUDENB -7440 -4436 -4509 1.07 — ? — 537 596 WATERLOO I -2084 1.013 -8351 1.165 1005 ■8388 037 OA UE -11400 — ? — ■ 836 (eo -9256 1. 135 1116 . (PO) ANCONA-Field or well name ■ -Field or well location - 1538 - z 1 Data at each I. 1 1 - p J well location 640 -H 100 J are in this order.. — ?— - Not available (EC) -Data from Eau Claire (PO) -Data from Potosi (GA) -Data from Gales ville (MS) - Data from Mt. Simon Fig. 2 - Z : and H 1.00 for observation points in the Mt. Simon. 12 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 PECATONIC/ ■ *I82 1.00 7.1.6 'ILLE 1.00 723 (FR) SOUTh -1497 1.002 513 •1417 -128' .00 I 1.00 '13 514 (FR) -227 595J Jf 1.00 605 -1200 1.004 405 ■ANCONA ' •' -1084 4i LAKE "-O? «PC BLOOMINGTON 6 -2283 X 1. 001 ■LEXINGTON 513 "-24I4 HUDSON 4,p U -2492 1.005 527 1.006 -480 'HERSCHERX CRESCENT CITY -2000 1.039 505 ■ MAHOMET -2519 1.026 536 LAKEB OF THE WOODS -1600 -1596 -'- 1.028 539 529 ROYAL CENTER ■* -296-: 1.00 563 ANCONA- ■ -1084 - 1.00 - 496 - -?- - (FR) - Field or well name Field or well location z 1 Data at each p ) well location H 100 J are in this order. Not available Data from Franconia Fig. 3 - Z, niirl II 1.00 for observation points in the Ironton-Galesville. HYDRODYNAMICS IN DEEP AQUIFERS 13 PECATONICA | ■ -?- I 1.00 \ ;735 [SOUTH ■ -497 i 1.006 512 512 (GLaSP)! -312 /'PLYMOUTH— ■ sit PONTI AC —■> — CRESCENT 1.00 ■ 511 -569 1.00 505 i^ -942 LAKE OF -■>- THE WOODS 502 I 008 ILAKESIOE j -3135 ! 1.009 677 ; LOUDEN' BROHAMMERB I -3927 1.003 486 / 506 ST. JACOB [ DUPO 1275 i 388 (KN) -4679 -47; 1.075 ■-?- 599 597 I SALEM CLAY CITY ■-7230 l.076(?) 913 (SH) ANCONA — Field or well name ■ — Field or well location + 288 — z Data at each 1.00 — p ) well location 499 - H'°° J are in this order -?- — Not available (GL) — Data from Glenwood (SP) — Data from St. Peter (KN) — Data from Knox (SH) — Data from Shakopee 40 KILOMETERS Fig. 4 and H 1.00 for observation points in the St. Peter. 14 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 1000 Seo level 2500 — N - 5000 — - 7500 10000 Pecotonico West Chicogo (N) Herscher Pontiocj Hudson Lamb Lake Bloomington Tuscolo Salem (S) Fig. P> 1.00 Z, and ground elevation for observation points in the Mt. Simon along N-S cross section. For West Chicago, data are given for four observation levels: A, B, C, and D. On the plot of values of p , the numbers opposite the boxes are values of Z for levels A, B, C, D. HYDRODYNAMICS IN DEEP AQUIFERS 15 1.15 1. 10 — 1.05 — 1.00 + 1000 —i 50 N Sea level 2500 -5000 Waverly (SW) Lamb Mahomet 20 40 Crescent City 60 80 Gary Royal Center Lake of the Woods (NE) Fig. 6 p, H-*--00, Z, and ground elevation for observation points in the Mt. Simon along NE-SW cross section. For Crescent City, Gary, and Royal Center, data are given for multiple observation levels: A, B, C. . . . On the plot of values of p , the numbers opposite the boxes are values of Z for levels A, B, C 16 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 T3 . S C ■g s to w o w O I • S ■ — i ^ c I 00 ■ H pud uo.i|DA8|a punojg e 1 2 S o 2 t> m CD fO > c/o en C I xs ofc c a oi f * n c — o y 2 N 3 fO fO o o CD 3 W > r ' — 1 XI to HI O PL, 00 ,H PUD U0!|DA8|9 punOJQ HYDRODYNAMICS IN DEEP AQUIFERS 17 the top of the aquifer. AH At W«, at a depth h r difference in h • is just balanced by the excess weight of the column of given by h r x (o — 1) 1.00 the iense water; therefore, no appreciable flow occurs at this depth or at greater depths. The thickness of the aquifer is assumed to be large in comparison with h r . At depths between and h r , flow rate is proportional to (h r — h) . (The effects of the mixing of fresh and dense waters are ignored here.) Therefore, at the lead- ing edge of the displacement front, flow occurs along the roof of the aquifer. Thus, the direction of flow in such systems is greatly influenced by structure. Difference in head across a saddle. — As relatively light water displaces heavier water near a saddle, differences in n^-^O can be caused by the differences in water density on either side of the saddle. The difference in head at points A]_ and B]_ AH^V B]_ , is given by AH 1 " 00 A. A' 2 A 2 ~1 (/?- l)dZ -J (p- l)dZ . i H J That is, the head at point Aj exceeds the head at point Bj by the amount AH,* g, . In a similar way, differences in h can exist between points inside and outside a dome. Thus, differences in head can exist, even if no flow occurs. Or if flow does occur, these differences in head can affect the forces available for causing flow. Troughs — "corrugated flow" .— As shown by Bond and Cartwright (1970), a trough can cause a difference in H 1 - 00 if the water is stratified, even though no flow occurs. If flow does occur, the force available to cause flow can be de- creased. When flow occurs through a series of troughs ("corrugated flow"), these effects are additive. Diffusion effects are assumed to be negligible. These are some of the parameters that must be taken into account when water level, water density, and pressure data are used to study flow in such complex aquifers. Conclusions From Present Study Water Composition and Density For the brines that were studied, relative density was found to be approx- imately proportional to the concentration of dissolved solids (fig. 9). Figure 9 18 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 280,000 260,000 20,000 Relative density, p Fig. ') - Relation between relative density and dissolved-solids content of brines in deep aquifers of the Illinois Basin. HYDRODYNAMICS IN DEEP AQUIFERS 19 was used to obtain an estimate of the relative density in cases where only the concentration of dissolved solids was known. Relative densities estimated in this manner are designated /'est. ^ n tables 1, 2, and 3. In figure 9 and else- where in this report the concentration of dissolved solids is expressed in terms of milligrams per liter. For dilute brines, the number of milligrams per liter (mg/1) is approximately equal to the number of parts per million by weight (ppm) . For more concentrated brines, mg/1 = ppm x p . Tables 1, 2, and 3 include some data on brines from the Michigan Basin. Since the composition of these brines differs considerably from that of Illinois Basin brines, data on Michigan Basin brines were not plotted in figure 9. Mt. Simon Aquifer Density of water vs . subsea depth . — The Mt . Simon Sandstone and a relatively permeable sandstone widely present at the base of the Eau Claire For- mation are hydrologically connected and are considered as one unit, called the Mt. Simon Aquifer (Suter et al., 1959). In this report the term Mt . Simon is used to refer to the aquifer and not to the stratigraphic unit. Along a line from about West Chicago to Tuscola, the relative density of the Mt . Simon water is approximately a linear function of subsea depth (fig. 10). As we move west- ward from this line, the density becomes smaller at a given elevation; as we move eastward, the density becomes greater at the same elevation. A hypersurface was fitted to the data presented in figure 10. The hyper- surface, which has the form of a truncated power series in the spatial coordinates x, y, and z: 2 2 2 p * (x, y, z) = a + ax + ay + a z + ax + ay + a z + . . . (Heigold, Mast, and Cartwright, 1971), provides a continuous relative density function approximation to the observed data. In the present study the hypersur- face was limited to the third order (20 terms). A trend surface (Sutterlin and Brig- ham, 1967) permits one to approximate a power series to values of a quantity that is a function of two independent variables. A hypersurface permits one to approxi- mate a power series to values of a quantity that is a function of three or more in- dependent variables. In the present case the relative density, p , is a function of latitude, longitude, and depth. The hypersurface that was referred to above was used to evaluate p at several values of Z to give the density distributions within the surfaces defined by these values of Z? These relative density distributions were used to obtain the iso-density lines presented in figure 11, A-G. This figure also gives the corresponding concentrations of dissolved solids (mg/1); therefore, an estimate of the concentration or of the relative density can be made for water from any depth at a given location. The dashed lines in figure 11, A-G, show the extrapolation of the calculated iso-density lines into regions where the top of the Mt . Simon Aquifer is below the given value of Z. These lines can be used to make a rough estimate of the salinity to be expected in aquifers directly above the Mt. Simon, if the assumption can be made that these aquifers are hydraulically connected with the Mt. Simon. The data in figure 11, A-G, are presented in a different fashion in figure 12, A-G, which shows the depths at which a selected value of relative density tThe fitting of the hypersurface and the calculation of the relative density distributions were done by Paul Heigold. 20 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 1. 10 1.09 1.08 - 1.07 - 1.06 1,05 - 1.04 1,03 — 1.02 — I. 01 1.00 — Western Illinois — North Centrol Illinois Northwestern Indiana □ Mt. Simon • Eau Claire STEEL USC0L4 V / )\ mo // ^MT. Sit 1000 -1500 2000 2500 3000 -3500 4000 -4500 Fig. 10 - Relation between p and Z for waters from the Eau Claire and the Mt. Simon in the Illinois Basin. HYDRODYNAMICS IN DEEP AQUIFERS 21 (or of salinity) is found at different locations. If we assume that the Mt. Simon water is made up of a number of incremental layers increasing in density with depth, we can visualize from figure 12 the tilting of the interfaces between these incremental layers as Mt. Simon brine is displaced by fresh water. Flow in the Mt. Simon Aquifer .— As stated above, in an aquifer that contains water of variable density we can determine whether flow occurs between two points only if we know (1) how p changes with respect to Z along possible flow paths between the two points, and (2) the head at each point. In the Mt. Simon, at a given location the density can be assumed to be a linear function of depth, within moderate depth intervals. Also, at a given subsea depth the density prob- ably can be assumed to vary linearly with distance, over short distance intervals. Therefore, the value of the quantity tp = [AH 1 * 00 ~(/> ave -DAZ] r ave. should indicate the general direction of flow and the approximate magnitude of the net force available to cause flow. (This force will generally be at an angle to the actual direction of flow; thus, it represents only one component of the total force .) This conclusion is based on a highly simplified picture of the Mt. Simon Aquifer. Essentially it assumes that the aquifer is contained between two saucers. The effects of saddles, domes, troughs, and corrugations described above are ignored. Where sufficient data are available, this procedure should give essen- tially the same results as the procedure described by McNeal (see p. 4). In figure 13 arrows are drawn whose lengths are proportional to t p /s for pairs of observation points. If other parameters, such as viscosity, permeability, and porosity, can be assumed to be constant, the length of a given arrow is a measure of the possible flow rate in the direction of the arrow. Of course, the actual direction of flow within the aquifer may not be in the direction of the arrow; the direction given is that of one component of the total flow vector. The quantity tp. was also calculated using extreme values of /^ rather than/) ave _ That is, for two points, P^ and P2 , the assumption was made that all of the water in the aquifer between P^ and P 2 had the same relative density, Pl» as the water at Pi; tp was then calculated. Likewise, the assumption was made that all of the water between ?i and P 2 had the same relative density, pry* as the water at P2, and tp was calculated. In a few cases such assumptions of extreme density values resulted in a reversal of the indicated direction of flow. This reversal occurred with the following pairs of points: Hudson and the South well, Crescent City and Herscher Northwest, Hudson and Ancona, Lamb and Pontiac, and St. Jacob and Salem. In all cases except the last pair, St. Jacob and Salem, the residual head was insignificant. In the case of flow between St. Jacob and Salem, a considerable flow vector from Salem to St. Jacob was in- dicated when the assumption was made that all of the water between the two points had the density of the water at Salem; over the elevation interval between the two observation points (about 4,000 feet), this assumption with respect to density probably is not warranted. Probably the directions given in figure 13 are reason- able indicators of the general directions of the forces available to cause flow. For various reasons, to be discussed later, the McLean County-Livingston County area is of particular interest. Therefore, in figure 14, values of % ave /s for this area are presented in some detail. This figure also gives the directions of flow that have been inferred from water-level measurements within three gas- storage reservoirs. 22 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 '.02. Isodensity within Mt. Simon /Q Isodensity projected ""^ into overlying for- mations (29,000) Total dissolved solids, mg/| O 20 40 60 80 100 C^-H-f Z=-2000 Z=-2500 Z=-3000 Fig. 11 - Relative density of HYDRODYNAMICS IN DEEP AQUIFERS 23 h> — *-f — S i 1 i/ \ Z=-350 4000 V^ Z=-4500 Z=-5000 Mt. Simon water at various values of Z 24 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 -3000' 3500 -.^ Value of Z at which water of relative density £> occurs within the Mt. Simon Value of Z projected into over- N lying strata, e.g., Eau Claire 20 40 60 80 100 p= 1.02 ( 29,000 mg/, TDS) p= 1.04 (56,000mg/, TDS) C ^=1.06(85,000(119/! TDS) Fig. 12 - Value of Z at which water HYDRODYNAMICS IN DEEP AQUIFERS 25 % \ « 1 r * i ; i...... /?=l.08(M3,000mg/| TDS) p= I.l0(l44,000mg/| TDS) / c - p 3 1 > k* — *-~r~ — |™~™J — 4% -w^/"" /' ""'" /- V _ "V 5 ^ 1 fj \ I \ x C f j ""~1 I ■■■ : i S. f. \ J^-^l — y0= 1.12 (I84,000mg/| TDS) I. jj I ) p=l.l4(22l,000mg/ | TDS) of given density occurs in the Mt. Simon. 26 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 Vector-, length is proportional to the magnitude of the gradient. Vector 5 magnitude is too large to be shown between two points. Kilometers Fig . 1 3 - (f )/s for pairs of points in the Mt. Simon. Arrows indicate general direction of flow. Length of arrows is proportional to net force available to cause flow. (Data for Dale and Clay City are for the Eau Claire and the Knox, respectively.) As far as .flow in the Mt. Simon Aquifer in the northern part of Illinois is concerned, the water-density data (figs. 10, 11, and 12) are subject to two possible interpretations. On the one hand, the data are consistent with the idea that fresh water, moving from the west and northwest toward the east, has dis- placed a heavy brine. On the other hand, the data fit the assumption that brine, moving from the east to the west, has displaced fresh water. By means of the HYDRODYNAMICS IN DEEP AQUIFERS 27 ANCONA o PONTIAC 10 LAKE n bloomington\; Miles 5 10 Kilometers I 2 I I 1 I I I I xx LEXINGTON P Vector scale (gradient, ^^ HUDSON Vector; length is proportional to the magnitude of the gradient. For the magnitude between Lake Bloomington and Lexington, the vector is too large to be restricted between the two points. Fig. 14 - E^> Direction of gradient within gas- storage reservoir )/s for pairs of points in the Mt. Simon in Livingston and McLean ^ave. Counties, Illinois. density data alone, one cannot determine which of these two interpretations is correct. But the water-density data, together with the data on H 1 -^, can give an indication of the direction of flow. The data in figure 13 indicate appreciable flow rates in the Mt. Simon Aquifer from northeastern Illinois into northwestern Indiana. The observed dif- 28 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 ferences between H ' values for Herscher and Crescent City, on the one hand, and for Gary and Royal Center, on the other, could result, even though the water were static, if a trough existed. One trough about 1,000 to 2,000 feet deep (or several smaller troughs in series), with fresh water on one side and water of relative density 1. 10 on the other, would be required to cause the differences in jjl.00 triat are observed. From what is known about the area, this condition does not appear likely. Probably the observed differences in h - 00 and p are proof of flow through the Mt. Simon toward the east and northeast in this area, that is, northwestern Indiana and the adjoining part of Illinois. At Royal Center, H 1 - 00 at the top of the Mt. Simon is about 40 to 50 feet greater than in the Ironton-Galesville (fig. 15). This is approximately the amount of head required to lift the Mt. Simon water {p = 1 . 07) up through the 600 ± foot interval between the Mt. Simon and the Ironton-Galesville. Thus, if conduits for flow exist, Mt. Simon water can move from the Mt. Simon Aquifer up into the Ironton-Galesville at Royal Center. The data taken at Lakeside strengthen this conclusion. Such conduits for flow might be supplied by faults in the strata between the Mt. Simon and the Ironton-Galesville. Considerable information is avail- able concerning faulting in the northwestern corner of Indiana (Dawson, 1952; Pinsak and Shaver, 1964; Swann, 1968; Bond et al., 1971). The Royal Center Fault is located near the Logansport Sag (fig. 16). Swann (1968, p. 12) shows a fault in the Jasper Sag, northwest of the Royal Center Fault. Thus, faults do exist, which may or may not serve as conduits for flow of water. The information given earlier about water density and H-'-'OO indicates that Mt. Simon water is flowing from northeastern Illinois into northwestern Indiana, then upward through the fault system in that area into the Ironton- Galesville. In most of northern Illinois the water in the Ironton-Galesville is rela- tively fresh. However, at Crescent City the Ironton-Galesville water contains 56,000 mg/1 of dissolved solids and has a relative density of 1.039. At Crescent City H 1 - 00 in the Mt. Simon Aquifer is about 220 feet greater than H 1,00 in the Ironton-Galesville; after allowance is made for the head required to lift Mt. Simon water up to the Ironton-Galesville, a net difference in head amounting to 170 feet remains. Evidently leakage from the Mt. Simon to the Ironton-Galesville has not occurred in the vicinity of Crescent City. Apparently the saline water that has flowed upward from the Mt. Simon to the Ironton-Galesville through the north- western Indiana faults has run down gradient through the Ironton-Galesville under the influence of gravity and has displaced fresh Ironton-Galesville water, at least as far as Crescent City. Suter et al. (1959, p. 54) have shown that heavy pumpage from the Ironton- Galesville has greatly lowered the piezometric surface in the area around Chicago. Presumably this pumpage has resulted in some lowering of the head in the Ironton- Galesville at points as far away as Royal Center. The flow of Mt. Simon water up through the fault system in northwestern Indiana might have been caused by the reduction in head that has resulted from pumpage from the Ironton-Galesville in the Chicago area. However, in northern Illinois the pattern of water densities in the Mt. Simon Aquifer indicates that fresh water has moved eastward through the Mt. Simon, displacing brine and mix- ing with the brine for a distance of 5 to 100 miles. HYDRODYNAMICS IN DEEP AQUIFERS 29 2 3> %• CO 2 o _ * * • IO §2 X o - IO IO ou PS o o L I , <* in < II II o o - O '• I m 1 •-* V < » < O o i, _ O o to o m o coco CO CO CO CO* 2 5 5co # • < LlLuO— p w (O a> o o CD a> £ c r — o o o -t! E c M 3 • o o U_ 2= CD LU^ CC<< (JCO U_ CD CD LUS — 30 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 MILES 50 V /<** Fault; downthrown side indicated Fig. 16 - Major faults and some anticlinal belts in the Illinois Basin. Estimates have been made of the rates of movement of this water under the influence of the observed heads (corrected for density effects) in the Mt. Si- mon. * These show that the water moves a few inches per year. At this rate, a million years or so would be required for the water movement that is inferred from ttm ^ ,. i n _ 2.27 x gradient (A H ' /mi) x permeability (darcys) *The rate of advance (m./yr = 1 £— t-z — — \ ^rr — j , fTTTZTTT porosity (fraction) x viscosity ( centipoises ) HYDRODYNAMICS IN DEEP AQUIFERS 31 our data. Evidently the major movement in the Mt. Simon has not been caused by pumpage from the Ironton-Galesville in modern times, but rather it is the re- sult of long-term natural forces. An estimate has been made also of the rate of movement to be expected as dense water flows through the Ironton-Galesville south westward from the Royal Center area under the influence of gravity alone. That is, dense Mt. Simon water [p = 1.045 to 1.070) was assumed to flow upward to the Ironton-Galesville and then settle as a result of the density contrast between this dense water and the original Ironton-Galesville water. In this case, too, a rate of a few inches per year was obtained, leading to the conclusion that about one million years would be required for this dense water (assumed to come from the Mt. Simon by way of the fault system) to flow through the Ironton-Galesville from the Jasper Sag to Crescent City. This agrees with the conclusion reached above about the time required for the displacement of brine by fresh water in the Mt. Simon. Probably water has flowed naturally through the Mt. Simon, then up through the faults and down along the bottom of the Ironton-Galesville for many years. Of course, the flow of water in the Mt. Simon Aquifer might have been accelerated if the gradients in H * at some time in the past were much larger than at present. For example, glaciation might have greatly changed the potential for flow, as postulated by McGinnis (1968). One can also speculate that the weight of the glaciers during Pleisto- cene time compressed the sedimentary rocks in the Illinois and the Michigan Basins and thereby caused a flexure of the rocks across the arch separating the two basins. Perhaps this flexure was sufficient to cause vertical fractures through which water could flow from the Mt. Simon to the Ironton-Galesville. Although saline water appears to have flowed in the Ironton-Galesville of northwestern Indiana and part of northeastern Illinois under natural forces for many years, no doubt in modern times flow of this saline water has been influ- enced by man-made forces. Rough estimates indicate that flow of the saline water under the influence of gravity could easily be reversed by changes in the piezometric surface induced by pumpage. Detailed study of the encroachment of this saline water into Galesville fresh-water sources is needed for specific local conditions . Besides the flow described above in the northern part of the area studied, another flow in the Mt. Simon Aquifer is indicated in the southern part of the area (fig. 13). Sizable flow vectors are shown southward toward Louden and on to St. Jacob, Salem, Clay City, and Dale. Possibly Mt. Simon water flows to the Rough Creek Fault Zone (fig. 16) and then upward through the faults and fractures in that area. If so, important inferences about oil accumulation can be drawn. For one thing, filtration of finely dispersed hydrocarbons from the moving water may have resulted in commercial accumulations of oil. Furthermore, in accordance with the principles laid down by Hubbert (19 53), any oil deposits that may exist in the Mt. Simon should be displaced. The indications of flow through the Mt. Simon Aquifer in the deep part of the Illinois Basin are based on data having questionable validity. Data are available for only a few locations, and the values for H-*--^ are deduced from drill-stem test results. If the DST results are in error by as much as two or three percent, the indicated flow directions may be changed. Such an error is not likely, but it is a possibility. Also, the flows in figure 13 were calculated on the assump- tion that the density of the interstitial water varies linearly with depth and with 32 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 distance. If the density actually increases more rapidly than this with depth, the forces available for flow are greater than indicated; on the other hand, if the density increases less rapidly, the force is less than indicated. Furthermore, some question exists about the water densities that should be used in the cal- culations . The value given for Salem, 1.165, appears reliable. No density data were available for Louden and Clay City; therefore, the Salem value, 1.165, was assumed. No Mt. Simon Sandstone Formation was present in the Cuppy well at Dale; the water samples from the St. Peter, Potosi, and Eau Claire in this well all had relative densities of approximately 1. 13; therefore this value was used in the calculations for figure 13. The absolute values of tp. change as different values are assumed for p±. However, the indicated flow direction, north to south, can be reversed only by the assumption of unreasonably small values for the densities of the interstitial waters; therefore, the uncertainty about water densities does not seriously affect our conclusions about the direction of flow. In the deeper part of the Illinois Basin, data for h • in the Mt. Simon Aquifer are available only for Salem, Louden, and St. Jacob. Eau Claire data are available for Dale, while Shakopee (Knox) data are available for Clay City. All of these data were used in making the calculations for figure 13. This pro- cedure is valid if we can assume that the Mt. Simon, Eau Claire, and Knox are hydraulically connected in this area; however, we have no assurance that they are connected. When Potosi (Knox) data from the Dale well were used instead of Eau Claire data, the results of the calculations indicated essentially no flow from Salem and Clay City toward Dale. Thus, our conclusions about flow in this area are uncertain. On the whole, though, most of the data indicate southerly flow in the deeper rocks in the southern part of Illinois. The calculated values of (^ ave ./s) in the southern part of the state are in general considerably larger than in the northern part. This is to be expec- ted since the permeability of the Mt. Simon Aquifer decreases as we go south- ward. Other things being equal, in order to cause the flow of a given volume of water, a rock having low permeability requires a greater value of C^p ave /s) than does a rock having high permeability. Cartwright (1970) found, from temperature measurements, indications that water is flowing upward in the area of the Rough Creek Fault Zone. This conclusion is consistent with the conclusions presented above about the likeli- hood of southward flow in the deeper part of the Illinois Basin. Possible anomalies in head exist at Ancona, at the South well, and at Newport. As far as Ancona is concerned, all of the indicated flow directions except one point toward Ancona (fig. 13). However, some of the values of ? ^°ave / s ma y not ^ e large enough to be significant. Conditions at Ancona and at the South well will be discussed later, in the section dealing with flow in the Ironton-Galesville (p. 37). As far as Newport is concerned, all of the indicated flow directions point outward. At Newport H • is about 300 feet greater than at observation points to the west in Illinois. About 100 to 200 feet of this head difference can be accounted for by the differences in elevation (1,000-1,500 feet) between the ob- servation point at Newport and those to the west of Newport. Thus, a 1, 000-foot interval containing water having an average density of 1.10 would result in a difference in H 1 • ^ ° equal to 1, 000 x 0. 10, or 100 feet. The remainder of the HYDRODYNAMICS IN DEEP AQUIFERS 33 difference between H ' for Newport and for the Illinois points (100 to 200 feet) should be available to cause flow away from Newport, unless, of course, it is diminished by the effects of intervening troughs. The high value of h • at Newport is probably the net result of two factors: (a) The ground elevation along the Cincinnati Arch is about 300 feet higher than at Newport; presumably some of the head in the outcropping Ordovician rocks along the arch is transmitted to the Cambrian Mt. Simon Aquifer, (b) The Mt. Simon rises more than 3,000 feet in going from Newport to the arch (fig. 17); a 3, 000-foot column of dense water {p ~ 1.05 to 1.10) would add 150 to 300 feet to the head. Possible explanation for random flow directions in the Mt. Simon Aquifer . — Locally the indicated flow directions in the Mt. Simon vary in almost a random fashion (figs. 13 and 14). Some of the apparent variation in flow direction may be due to errors in the data used. But this is not a likely explanation for all of the variation, because the water-level measurements, water sampling, and analy- sis are generally made with considerable care. In particular, in a given reservoir the data from well to well are consistent with respect to base elevation. The reported gradients usually are based on observations in about a dozen wells. The observed gradients appear to result from real differences in the heads that exist in various parts of the reservoir. How, then, are the random directions of apparent flow to be explained? As indicated above, in an aquifer, like the Mt. Simon Aquifer, that contains stratified water of variable density, flow is a complex function of water density, hydraulic head, permeability, and structure. By way of illustration, a hypo- thetical case has been set up to show flow patterns that can occur when fresh water encroaches into an aquifer that is initially saturated with dense saline water (fig. 18). Obviously the direction of flow in one part of the aquifer can be at right angles to the direction of flow in another part of the aquifer; in certain parts the flows can even be in opposite directions. Furthermore, the direction of flow can change as the displacement process continues. For example, early in the process, light, relatively fresh water will generally flow around "lows" in the roof of the aquifer. Later, as the interface between light and heavy water is displaced downward, water can flow under these "lows. " Of course, similar effects can occur, in reverse, as dense water displaces a lighter water. To prove that this kind of flow is occurring in any given aquifer would require far more data than are available. The effects illustrated in figure 18 do appear to give a reasonable mechanism for explaining the variation in apparent flow direction that is observed in the Mt. Simon in the Illinois Basin. Other possibilities also should be kept in mind. In some parts of the aquifer the observed differences in head may be just enough to balance heavy water on the side of a trough or in a series of troughs; or the differences in head may balance relatively heavy water under a dome or across a saddle, leaving no excess head to cause flow, as pointed out previously (p. 17). That is, differences in head can exist even though the water is not flowing. Perhaps some of the gradients that have been deduced for the Mt. Simon (figs. 13 and 14) mirror such static situations. Here, again, proof would require much more data, but the possibility appears reasonable. 34 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 °° 1 | Dense water \';-;:';:';:';:\ Fresh water A - Part of hypothetical basin. In the north, fresh water invades shallower part of basin, Fresh water reaches spill point of dome Di and starts to displace dense water from dome. Note opposite directions of flow of fresh water near spill point. ! "2 Dense water |:|:;>x;>| Fresh water B Second stage oi Invasion. Fresh water displaces dense wate opposite directions oi u*>w Ln easl and wei I ends oi dome, Fig. 17 - Displacement of dense water HYDRODYNAMICS IN DEEP AQUIFERS 35 C - Invading fresh water flows around lows L^ and L2. Note opposite directions of flow along periphery of lows L^ and L2 . D - Advanced stage in displacement process. Note lows under which little or no flow occurs. by fresh water in a hypothetical aquifer 36 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 100 TENN Kilometers 3000 Contour, intervol 1000 ft ^^^ Fault, downthrown side indicated Fig. 18 - Structure on top of Mt. Simon Formation (prepared by T. C. Buschbach and T. L. Chamberlin) . HYDRODYNAMICS IN DEEP AQUIFERS 37 Flow in the Ironton-Galesville and St. Peter Aquifers The data in table 2 on H * and p for the Ironton-Galesville were sub- jected to the same treatment as described above for data from the Mt. Simon Aquifer (fig. 19). Density data were not available for water from the Ironton- Galesville at Lake of the Woods; therefore, the density of Ironton-Galesville water at Royal Center was used in the calculations for the interval between Lake of the Woods and Royal Center. Likewise, the density of Crescent City water was used in the calculations for the interval between Lake of the Woods and Crescent City. In a general way, flow is indicated from the north and the northwest toward the central and western parts of Illinois. However, a number of anomalous situations appear in figure 19. A small flow is indicated from Shanghai toward Ancona, while the other data generally indicate flow toward Shanghai. In figure 19, on lines showing flow between Ancona and other points, all arrows, except the one from Herscher, point toward Ancona; therefore, a potential sink (an area of low head) may exist in the Ironton-Galesville in the vicinity of Ancona. In some ways, figure 19, showing flow in the Ironton-Galesville, re- sembles figure 13, showing flow in the Mt. Simon Aquifer, in the Ancona area. In figure 13 all arrows, with the exception of the one toward the South well, also point toward Ancona; the value of the gradient toward South may not be significant. Perhaps a sink exists in the Mt. Simon also in the vincinity of Ancona. Since the Mt. Simon rests on granite, such a condition can exist only if water is flow- ing upward from the Mt. Simon to the Ironton-Galesville, displacing water from the Ironton-Galesville into overlying aquifers. A net head difference of about 120 to 140 feet exists between the Mt. Simon and the Ironton-Galesville, indi- cating lack of communication between the two aquifers. However, salinity data indicate that Mt. Simon water may be flowing upward to the Ironton-Galesville in the Ancona area. In the southeast dome of the Ancona reservoir the Ironton- Galesville water contains 3, 800 mg/1 of total dissolved solids (TDS), while in the northwest dome it contains 6, 7 00 mg/1. These values can be compared with those in surrounding reservoirs: Troy Grove - 720 mg/1, Herscher - 2,528 mg/1, Pontiac - 1, 300 mg/1, Lake Bloomington - 1, 955 mg/1. On the basis of its depth and location, the Ironton-Galesville water at Ancona would be expected to contain only about 1, 200 mg/1 TDS. Thus, the Ancona Ironton-Galesville water contains three to five times the dissolved solids that would be expected; furthermore, the solids content is about one-fifth to one-third of that of the Mt. Simon. Perhaps Mt. Simon water, flowing upward through the Eau Claire to the Ironton-Galesville, has mixed with the native Ironton-Galesville water to give the observed salinities. Willman et al. (1942, p. 285) suggest that the presence of salty water in some wells in central La Salle County is the result of the introduction of water from the Mt. Simon into higher fresh-water aquifers through joints in the intervening strata. The data in figure 13 and figure 19 and the information about water sa- linities can be explained if we assume that one or more faults in the general vi- cinity of Ancona permit vertical flow from the Mt. Simon Aquifer upward to the Ironton-Galesville and higher aquifers. Faults are known to exist at Troy Grove; although these faults do not permit flow from the Mt. Simon to the Ironton-Gales- ville, they do permit flow between the Mt. Simon and zones in the Eau Claire 38 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 47 HOLLAND .-■■/ Vector; length is proportional to the magnitude of the gradient. Vector; magnitude is too large to be shown between two points. (2.91) Magnitude of gradient llllllllll Vector scale (gradient, =|- 20 40 3 Miles 40 Kilometers Fig. 19 - (f )/s for pairs of points in the Ironton-Galesville. Arrows indicate P avc . general direction of flow. Length of arrows is proportional to net force available to cause flow. (Data for Holland are for the Franconia.) HYDRODYNAMICS IN DEEP AQUIFERS 39 (Buschbach and Bond, 1967, p. 49). It is reasonable to expect faults of this kind to exist also at other places, like Ancona, along the La Salle Anticlinal Belt. A fault of this kind, if it does exist, probably is located east of Ancona, since the local gradient in the Mt. Simon Aquifer at Ancona points toward the east. What has been said above about Ancona applies also, in some degree, to the area around Shanghai and the South well. The data for that area could be explained by the assumption that a fault exists that permits some upward flow but not enough flow to equalize the heads in the Mt. Simon and the Ironton- Galesville. The data plotted in figure 19 represent only the information that was un- covered incidental to the study of relatively heavy brines. Much more informa- tion about the Ironton-Galesville, especially where it contains fresh water, is available. Since water from the Ironton-Galesville is used locally in many parts of the state, it is not surprising that data from relatively few points should pre- sent the confusing pattern shown in figure 19. Probably a detailed study of data from fresh-water wells would resolve some of the apparent anomalies. Values of H * 00 for the St. Peter are given in table 3. Here, as for the Ironton-Galesville, only the data uncovered incidental to the study of heavy brines are tabulated. Much more data are available for fresh-water wells that produce from the St. Peter. For the northern half of Illinois, the data in table 3 indicate no broad general pattern of flow in the St. Peter. Water is withdrawn from the St. Peter locally at many places in northern Illinois. Because of the sparsity of data pre- sented here, the effects of local withdrawals are not revealed. In the southern part of Illinois, data on water density, water levels, and formation pressures for the St. Peter, Ironton-Galesville, and intervening formations are sparse. In figure 20 all of the available water-density data for these formations are plotted against subsea depth; data from Meents et al. (195 2), listed in table 4(app. 2), are also included. If the assumption is made that these strata are connected hydraulically, which is questionable, the density data in- dicate that these rocks have been flushed by relatively fresh water flowing gen- erally toward the south and east. In figure 21, which presents data for both p and Z, the S-shaped line marks a fairly sharp boundary between what may be paleobrines, in the southeastern part of the Illinois Basin, and the less dense in- vading waters from the northwest. To the north and west of this S-shaped line the density of the formation waters, for a given subsea depth, is considerably less than the density at the same depth southeast of the line. The S-shaped line of demarcation between dense and light waters in the interval from the St. Peter to the Ironton-Galesville (fig. 21) is similar to the iso- cons for St. Peter waters given by Meents et al . (1952, fig. 13). It also resembles the curves that were deduced from the hypersurface that was fitted to the p* (x, y, z) data for the Mt. Simon Aquifer (fig. 11) . Perhaps the heavy waters in all of these deep aquifers are banked up against the north and west sides of troughs in the La Salle and Clay City Anticlinal Belts (fig. 16). The water-density data indicate that fresh water has flowed into the interval from the St. Peter to the Ironton-Galesville from the northwest toward the southeast; however, with the density data alone one cannot establish whether or not the water is still flowing. To do this would require accurate data for H 1 • ^ also; such data are not available for this interval in the southern part of the Illinois 40 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 § 5 (NJ Q_ whw Oly i o o o GO o CD o in d .jQ r^ en ro CQ ro p >, o o o co O c CD > p CD ro O 6 CD 6 "Si T3 P o CO CD o >-< CD ro i=l 03 O P H ro CO O r0 Q 6 o CD CD o si ,12 1 1 1 1 1 i i CO ID £ J CD o ,_, CM CO •^r LO 1 c P >-i co ^r ^ ^r "sT" ■sT ^r •- 1 p o o CD o CD o , 1 -t-> *-" o CD > en 0) CO T3 P O a to +-> P CD CO CD o o o CD a in i-! ID c o o 1 o o CO c CO o o S-i XS o CD £ o 1 — 1 ,£} rO in CD 6 ' s: p CM c CO p o o s: CD CD o in P CO CD Si 3 ^ >i p t O r0 CD O 6 h o o CD CM LO 6 Q 4-1 P CD O p CD o o P O CO 3 Hi CD E CD £ E O N i CD CD ro ro T3 ro a £ ro i-i O CO CD u CD M ro i-l o si ro ra o L-, m o CO ro P CD i i 1 I 1 , i o in 0) a) CM CO "vT LO CD r>~ CO ro 6 o CO P CD CO CD Q. CD CO CO CO CO CO CO CO O S-i CD 2 S-I O O CO CD LO ro 1 6 1 LO ra CM O O £ ^ CO in . ro CM o N ro CD X! £ p o o P. p CD £ o ra CO CD CM d. +J >, CD >-c S-i C u CD CD o CD CD a CD C C c o ■^r CD CD CD in CM | p CD ro CD Si o U o ' CD CM O O O , 1 , | , 1 rQ CD CO o CO >i r0 ro >1 C O CO CO CD CO >-i i-> 5* >. ro o o CD CD S-i u P H CD HI ro CD O PS O £ o ra £ m 1 1 1 i 1 1 1 CD P O LO CO [-^ 00 CD O ,_, PC £ — Direction of flow of fresh water PICKEL •-527I 1.073 20 40 Miles Fig. 21 - Flushing of brine by fresh water, as indicated by variation of p at corresponding values of Z, St. Peter through Ironton-Galesville . 42 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 Basin. However, Cartwright (1970), on the basis of temperature measurements, concluded that water is now flowing upward in the southeastern part of the basin. Possibly water is still flowing toward the southeast in the interval from the St. Peter to the Ironton-Galesville . Vertical Flow (a) Vertical flow from the Mt. Simon Aquifer to the St. Peter . — The values of H ' calculated for the Mt. Simon are generally greater than the values of H 1 * 00 for the St. Peter (tables 1 and 3). Bond and Cartwright (1970, p. 1496) show that if a conduit for flow exists, water flows upward from one aquifer to another if (h;- oo -h;- oo )>(»-uo)az . 2 1 I c Here Hi i- s the fresh-water head at the top of the lower aquifer, Hi ' is the fresh-water head at the bottom of the upper aquifer, p„ is the density of the water in the lower aquifer, relative to fresh water, and AZ C is the vertical thick- ness of the intervening cap rock. Table 5 (app. 2) gives the results of calculations of [»»l - -k 00 f ] - K,s.- ■>«. for ten locations in the Illinois Basin for which data are available. The calcula- tions show that water should flow upward from the Mt. Simon to the St. Peter at points from Shanghai and Ancona in the north to about Louden in Fayette County. At St. Jacob and Salem, in Madison and Marion Counties, respectively, the dif- ference in H ' is not great enough to cause upward flow. Water can flow downward if (p l - 1)AZ H i.oo_ H i.oo c Here Pi is the relative density of the water in the upper aquifer, in this case the St. Peter. Calculation shows that at Salem [ H Mt° S.- H St°P.] iS n0t leSS than ( 'st.P. - 1 ' AZ C but is 148 greater (table 5). Therefore, at Salem water cannot flow downward from the St. Peter to the Mt. Simon either. Bond and Cartwright (1970, p. 1496) show that if ( Pl - DAZ c < (hJ* 00 - h5* 00 )< (p 2 ~ 1)AZ c , a static interface exists between the two waters in the rock between the two aqui- fers. The distance from the bottom of the cap rock (i.e., top of the lower aquifer) to the equilibrium interface, AZ , is given by eq. Application of this equation to the data from the Johnson well at Salem shows that the equilibrium interface in a conduit between the Mt. Simon Aquifer and the St. Peter should be about 1,640 feet above the top of the Mt. Simon. HYDRODYNAMICS IN DEEP AQUIFERS 43 The preceding discussion presents an overly simplified picture of the potential for vertical flow. It ignores the presence of other porous zones, in the Ironton-Galesville and the Knox, for example. These zones could have hy- draulic heads greater than those in the Mt. Simon or less than those in the St. Peter, but this is not likely. If the head in these intervening beds lies between the heads for the Mt. Simon and the St. Peter, our conclusions about vertical flow should hold, qualitatively. (b) Vertical flow from the Mt. Simon Aquifer to the Ironton-Galesville . — The values of j! M iVIt.S H Glsvl. (/ Mt.S. 1)AZ c are given in table 6 (app.2) for those locations for which Mt. Simon and Ironton- Galesville data are available. At Pecatonica and at Brookville a natural difference in head of about 3 feet will force Ironton-Galesville water down to the Mt. Simon if any conduit for flow exists. At Royal Center, as noted before, the difference between the head in the Mt. Simon Aquifer and that in the Ironton-Galesville is just enough to lift Mt. Simon water up to the Ironton-Galesville. At most locations in northern Illinois, a residual force equivalent to about 100 to 175 feet of fresh-water head is available to cause flow from the Mt. Simon up to the Ironton-Galesville. Most of the measurements reported here were made in the past twenty years. Especially in the Ironton-Galesville and the St. Peter, they reflect the effects of pumpage in modern times. As noted previously, Suter et al. (1959) have shown that in northeastern Illinois the head in the Cambrian-Ordovician Aquifer, of which the Ironton-Galesville and the St. Peter are a part, has been lowered considerably as a result of this pumpage. In 1898 the static water level in the St. Peter at Tuscola was about 150 feet above its present level (Habermeyer, 1925). Before withdrawal of water was begun, the heads in the Mt . Simon and in the overlying aquifers were probably nearly balanced, with little net force avail- able for vertical flow. Measurements of the head of water in wells drilled into porous zones above and below a cap rock have been used to indicate whether or not the cap rock may leak (Bays, 1964). The assumption is made that if an avenue for leak- age exists, the head in the two zones must become equal over geologic time. Therefore, if a difference in head is observed, the conclusion is reached that the cap rock is tight. This conclusion may be valid if the difference in head across the cap rock has existed for a long time. But if the difference in head has existed for only a relatively short time, the flow of water through any faults and fractures in the cap rock may not have been sufficient to equalize the heads above and be- low the cap rock. Therefore, conduits for flow may exist even if a head difference is observed, if this head difference has developed recently as a result of pump- age, as appears likely in the deeper aquifers of northern Illinois. (c) Vertical flow from the Ironton-Galesville to the St. Peter . — Data for both the Ironton-Galesville and the St. Peter are available for only a few locations (table 7, app. 2) . The data indicate that in most of northern Illinois little or no difference in head exists to cause flow between these two aquifers. At Pecatonica water would flow downward through any conduit from the St. Peter to the Ironton-Galesville, under the influence of a head 44 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 difference of about 20 feet. At Crescent City water would also flow downward, under a head of about 25 feet; because of the high density of the Ironton-Galesville water, more than 80 feet of head would be required to force Ironton-Galesville water up into the St. Peter. The results of the above calculations with respect to vertical flow be- tween the Mt. Simon, the Ironton-Galesville, and the St. Peter are mapped in fig- ure 22. Origin of Illinois Basin Brines Bredehoeftetal. (1963), Clayton etal. (1966), and Graf etal. (1965, 1966) have discussed mechanisms for the concentration of sea water that might explain the origin of the highly saline brines found in the deep part of the Illinois Basin. They concluded that the water in the deep aquifers in the basin is flow- ing and that some of the water is being discharged upward through clay shales that act as osmotic membranes . The present study indicates that in recent times, prior to pumpage, the vertical head differences in the deeper rocks of the Illinois Basin were scarcely large enough to cause upward flow through an open conduit, let alone through a very tight shale that might filter out dissolved salts (fig. 22). If any water now flows upward, say from the Mt. Simon to porous formations such as the Ironton- Galesville and the St. Peter in the central part of the basin, most likely it flows through fractures in the tight intervening strata. SOME CONCLUSIONS ABOUT SYSTEMS CONTAINING WATER OF VARIABLE DENSITY Oil and Gas Accumulation Hydrodynamic potential values, deduced from pressure readings and water-level observations, have been used in attacking a number of problems re- lated to oil and gas accumulation. These problems are encountered in the study of tilted oil-water interfaces, hydrodynamic sinks, and long-distance flow through aquifers. Conclusions from some of these studies may need modification when the effects of variable water density in inhomogeneous strata, discussed above, are taken into consideration. Some of these effects are discussed in the following paragraphs . Tilted Oil-Water Interface Hubbert (1953) discusses some of the implications of potential gradients with respect to flow in aquifers in which oil or gas reservoirs exist. In particular, he shows that in an aquifer whose water is constant in composition : (1) A sloping potentiometric surface is always accompanied by flow (p. 1974), and (2) a sloping potentiometric surface causes a tilting of the interface between the water and an oil or gas deposit in a reservoir (p. 1988). Later, in a general discussion of tilted oil-water interfaces (p. 2023), Hubbert concludes: The only way, therefore, that a tilted oil-water interface can be sustained indefinitely except by a dynamic ground- water environment is for the oil to be restrained by some kind of impervious seal, such as an asphalt stratum. HYDRODYNAMICS IN DEEP AQUIFERS 45 LAKE OF THE WOODS Top of Mt. Simon to bottom of Galesville Calculated from average of 6 values of H 100 and p near top of Mt. Simon 29l-9| ?| 139 Mt. Simon to Ironton-Galesville Ironton-Galesville to St. Peter Fig. 22 - Head, [ AH 1.00 (n — 1) AZ] , available to cause upward flow. Nega- tive value indicates head insufficient to cause upward flow, p ~ rela- tive density of water in lower aquifer. 46 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 This conclusion appears to be valid, if the density of the water below and around the oil deposit is constant. But if the density of the water varies and if the aqui- fer rock is anisotropic and contains troughs and "corrugated" flow paths, a grad- ient in head or in potential can be maintained indefinitely without flow. Such a gradient will cause a tilt in the oil-water interface just like the tilt that accom- panies a gradient that is caused by flow. Furthermore, in such a variable-density aquifer, this tilt may be maintained indefinitely without any flushing by invading waters . Thus far, no definite evidence is known for the existence of such oil reservoirs, that is, reservoirs with tilted oil- water interfaces caused by strati- fied waters of variable density that are not flowing. But many reservoirs are known in which variations exist in the elevation of the oil-water contact through- out the field; at least some of these variations may be the result of the density effects described above. Many Illinois oil deposits are found off the tops of structures. Often the reason given is that the best porosity is off structure; in some cases a better explanation might be that the head differences caused by stratified waters in an inhomogeneous reservoir rock have resulted in the dis- placement of the oil deposit. Uniform reservoir rocks should not contain such anomalous deposits. Likewise, aquifers filled with water of constant composition and density should not contain these anomalous oil deposits. But any oil-bearing strata having irregular flow paths (i.e., strata with cross-bedding, channeling, and pinchouts) and containing water whose density varies could have reservoirs with tilted oil- water interfaces or deposits located off the tops of structures. Long-Distance Flow Through Aquifers A number of researchers have used measurements of potential or of head to prove that water has flowed through aquifers for a considerable distance. For example, Hitchon (1969a and b) , as a result of such a study, concluded that water is flowing from the foothills in western Alberta eastward to the Ft. McMurray tar sands area through various aquifers. In view of what has been said about the effects of stratified dense waters in troughs, we need to consider the possibility that some of the potential dif- ferences observed in such studies may not be caused by flow. In some instances the observed potential differences may simply represent the hydraulic head re- quired to balance static layers of relatively dense water on the sides of a series of troughs . Underground Waste Disposal Deep wells are often used for the disposal of liquid industrial wastes (Bergstrom, 1968; Warner, 1965; Ives and Eddy, 1968). Since these liquid wastes contain high concentrations of dissolved materials, they often have high densities relative to fresh water. Obviously the principles outlined in other sections of this report will have application to problems connected with the underground flow of these heavy waste solutions. For example, suppose a pickle liquor from a steel plant, relative density 1.22, is injected near the bottom of an aquifer that contains water whose rela- tive density is 1.10. In such a system no impermeable cap rock is needed to protect fresh water in higher aquifers. Unless the point of injection is at a HYDRODYNAMICS IN DEEP AQUIFERS 47 structural low, the pickle liquor will flow downward under the influence of gravi- ty. Suppose that the bottom of the aquifer dips, say 40 feet per mile. The grav- itational force available to cause flow will be equivalent to a head of 40 x (1 . 22-1 . 10) , or 4 . 8 feet per mile. From this head and the porosity and permea- bility of the rock, the rate of advance of the injected liquid can be calculated. The rate of movement under the influence of gravity will be quite small, in most cases of the order of inches per year. On the other hand, suppose that a light, toxic waste liquid, having a relative density of approximately 1.00, is injected into an aquifer at a point 1,000 feet below the contact between a brine having a relative density of 1.10 and fresh water. The brine will not necessarily serve as a barrier against up- ward flow of the injected liquid. As a matter of fact, the injected liquid can be expected to flow upward under the influence of gravity. The force avail- able to cause flow will be equivalent to a gradient of 0. 10 foot of head per foot of vertical distance. The rate of upward movement can be estimated if the poros- ity and permeability of the aquifer rock are known. In certain cases, depending on the porosity and permeability of the rock and the thickness of the intervening layer of dense water, as well as the density of this water, flow rates can be high enough to cause contamination of the fresh water by the injected liquid within a reasonable period of time. In cases like this, a tight cap rock above the heavy-brine aquifer is an absolute necessity if upper fresh-water zones are to be protected against contamination. Of course, one possible solution to the problem would be to mix the toxic waste with a heavy brine to give a dense in- jection mixture that would settle rather than rise through the aquifer. If the aquifer into which the waste is injected contains fresh water in its upper zones, we need to consider the possibility that pumpage of this fresh water may reduce the head enough to cause the injected solution to rise and pollute the fresh-water zones. If a heavy waste material is injected under a relatively light saline water, the saline water will act as a screen to prevent the heavier waste water from rising into the fresh-water zone. Long before the waste water can reach the fresh-water zone, the fresh water will be displaced by the rising saline water. Of course, if waste liquid is injected into an aquifer under sufficiently high pressure, it can be forced up into a fresh-water zone if conduits for flow are present. Proper completion of the injection well, with suitable provision for monitoring, should prevent this, especially if the injection pressure is kept with- in reasonable limits. These limits can be chosen if one knows the densities of the liquids and the vertical intervals involved. For example, suppose that in the case outlined above, 1, 000 feet of saline water {p = 1. 10) lies between the fresh water and the injected waste {p = 1.22). Assume that a channel of communication exists from the point of injection up to the fresh-water zone; this channel might be the result of a poor cement job, or it might be due to fracturing of the rock around the well bore. In order to raise the injected waste liquid up to the fresh- water zone, a fresh-water head equal to 1, 000 x (1 . 22-1 . 00) , or 220 feet, would be required. If H 1,00 , prior to injection, is the same in the fresh-water zone and at the point of injection, a pressure difference equivalent to a head of 220 feet can be tolerated without any possibility of forcing the waste liquid up into the fresh-water zone. That is, an injection pressure of 0.433 x 220, or 95 psi, in excess of the original pressure can be used without fear of raising the injected liquid up to the fresh-water zone. If H 1 -^ is greater at the point of injection than it is in the fresh-water zone, which is the usual case, the pressure limit will be correspondingly lower. 48 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 Each underground disposal well presents a special problem. However, the examples mentioned should show that gravitational effects caused by dif- ferences between the density of the native interstitial water and the density of the injected liquid may need to be taken into account in the design of a disposal well. SUMMARY 1. Brines in the deep aquifers of the Illinois Basin are highly stratified. Over a distance of about 120 miles, along a line from West Chicago to Tuscola, the density of the interstitial water in the Mt. Simon Aquifer is approximately a linear function of subsea depth. To the west of this line the density is less, while to the east the density is greater, for a given elevation. 2. In the northern third of Illinois, water flows through the Mt. Simon Aquifer from the west to the east. In the northwestern part of Indiana, probably water flows from the Mt. Simon Aquifer up through faults and fractures to the Ironton-Galesville . This saline water from the Mt. Simon, flowing in a south- westerly direction in the Ironton-Galesville under the influence of gravity, appears to have penetrated at least as far as Crescent City. 3. Under present conditions, the indicated flow in the Mt. Simon Aquifer, up into the Ironton-Galesville, and down to Crescent City would have required about one million years. 4. In the deeper part of the basin, evidence exists that water in the Mt. Simon Aquifer is flowing southward, but some of this evidence is of question- able validity. 5. In some areas local flow directions in the Mt. Simon Aquifer vary in almost a random manner. The variation in flow direction may be caused by the complex nature of flow in such a stratified water system. As light water dis- places heavier water in an aquifer, most of the flow occurs along the roof of the aquifer; therefore, local direction of flow is influenced greatly by the structure on the top of the aquifer. Saddles, domes, troughs, and corrugated flow paths affect the heads, and, therefore, the forces available to cause flow. 6. In the northern part of the Illinois Basin, some net head exists (about 100 to 200 feet) to cause vertical flow from the Mt. Simon Aquifer to shallower aquifers. Probably little or no effective head difference existed prior to modern pumpage from the shallower aquifers. In the deep aquifers that were studied, no evidence was found for abnormal heads that might have been caused by glaciation. 7. In an aquifer that contains stratified brines, a tilted oil-water inter- face can exist with zero flow in the water phase. 8. Principles of flow in variable-density aquifers have important appli- cations in problems related to underground waste disposal. REFERENCES Bays, C. A., 1964, Groundwater and underground gas storage: Groundwater, v. 2, no. 4, p. 25-42. Bergstrom, R. E., 1968, Feasibility of subsurface disposal of industrial wastes in Illinois: Illinois Geol . Survey Circ. 426, 18 p. HYDRODYNAMICS IN DEEP AQUIFERS 49 Bond, D. C. , and Keros Cartwright, 1970, Pressure observations and water den- sities in aquifers and their relation to problems in gas storage: Jour. Petroleum Technology, v. XXII, p. 1492-1498. Bond, D. C, et al., 1971, Possible future petroleum potential of Region 9 — Illi- nois Basin, Cincinnati Arch, and northern Mississippi Embayment, in Ira H. Cram, ed., Future petroleum provinces of the United States — their geology and potential: AAPG Memoir 15, v. 2, p. 1165-1218. Bredehoeft, J. D., C. R. Blyth, W. A. White, and G. B. Maxey, 1963, Possible mechanism for concentration of brines in subsurface formations, AAPG Bull., v. 47, no. 2, p. 257-269. Buschbach, T. C, and D. C. Bond, 1967, Underground storage of natural gas in Illinois - 1967: Illinois Geol. Survey 111. Pet. 86, 54 p. Cartwright, Keros, 1970, Ground-water discharge in the Illinois Basin as suggested by temperature anomalies: Water Resources Research, v. 6, no. 3, p. 912-918. Clayton, R. N., Irving Friedman, D. L. Graf, T. K. Mayeda, W. F. Meents, and N. F. Shimp, 1966, The origin of saline formation waters, I. Isotopic composition: Jour. Geophys. Research, v. 71, no. 16, p. 3869-3882. Dawson, T. A., 1952, Map showing generalized structure of Trenton Limestone in Indiana: Indiana Geol. Survey Misc. Map 3. Dolan, J. P., C. A. Einarsen, and G. A. Hill, 1957, Special applications of drill stem test pressure data: Jour. Petroleum Technology, v. IX, no. 11, p. 318-324. Graf, D. L. , Irving Friedman, and W. F. Meents, 1965, The origin of saline for- mation waters. II — Isotopic fractionation by shale micropore systems: Illinois Geol. Survey Circ . 393, 32 p. Graf, D. L. , W. F. Meents, Irving Friedman, and N . F. Shimp, 1966, The origin of saline formation waters. Ill— Calcium chloride waters: Illinois Geol. Survey Circ. 397, 60 p. Habermeyer, G. C, and others, 1925, Public ground-water supplies in Illinois- Illinois Water Survey Bull. 21, p. 651. Hanshaw, B. B., and G. A. Hill, 1969, Geochemistry and hydrodynamics of the Paradox Basin region, Utah, Colorado and New Mexico: Chemical Geolo- gy, v, 4, no. 1/2, p. 263-294. Heigold, P. C, R t F. Mast, and Keros Cartwright, 1971, Temperature distri- butions and ground-water movement associated with oil fields in the Fairfield Basin, Illinois, in D . C. Bond, chairman, Proceedings of Symposium on future petroleum potential of NPC Region 9 (Illinois Basin, Cincinnati Arch, and northern part of Mississippi Embayment): Illinois Geol. Survey 111. Pet. 95, p. 127-140. Hitchon, Brian, 1969a, Fluid flow in the western Canada sedimentary basin— 1. Effect of topography: Water Resources Research, v. 5, no. 1, p. 186- 195. 50 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 470 Hitchon, Brian, 196 9b, Fluid flow in the western Canada sedimentary basin— 2. Effect of geology: Water Resources Research, v. 5, no. 2, p. 460-469. Hubbert, M. K. , 1940, The theory of ground-water motion: Jour. Geology, v. 48, no. 8, p. 785-944. Hubbert, M. K. , 1953, Entrapment of petroleum under hydrodynamic conditions: AAPGBull., v. 37, no. 8, p. 1954-2026. Ives, R. E., and G. E. Eddy, 1968, Subsurface disposal of industrial wastes: Interstate Oil Compact Commission, Oklahoma City, 109 p. Katz, D. L., M. R. Tek, K. H. Coats, M. L. Katz, S. C. Jones, and M. C. Miller, 1963, Movement of underground water in contact with natural gas: American Gas Assn. , New York, 323 p. Lusczynski, N. J., 1961, Head and flow of ground water of variable density: Jour. Geophys. Research, v. 66, no. 12, p. 4247-4256. McGinnis, L. D., 1968, Glaciation as a possible cause of mineral deposition: Econ. Geology, v. 63, p. 390-400. McNeal, R. P., 1965, Hydrodynamics of the Permian Basin, in. Addison Young and J. E. Galley, eds . , Fluids in subsurface environments, a symposium: AAPG Memoir 4, p. 308-326. Meents, W. F. , A. H. Bell, O. W. Rees, and W. G. Tilbury, 1952, Illinois oil- field brines — Their geologic occurrence and chemical compositions: Illi- nois Geol. Survey 111. Pet. 66, 38 p. Ogata, Akio, 1970, Theory of dispersion in a granular medium: USGS Prof. Paper 411-1, 34 p. Pinsak, A. P., and R. H. Shaver, 1964, The Silurian formations of northern Indiana: Indiana Geol. Survey Bull. 32, 87 p. Suter, Max, R. E. Bergstrom, H. F. Smith, G. H. Emrich, W. C. Walton, and T. E. Larson, 1959, Preliminary report on ground- water resources of the Chicago region, Illinois: 111. Water Survey and 111. Geol. Survey, Coop. Ground- Water Rept. 1, 89 p. Sutterlin, P. G., and R. J. Brigham, 1967, Trend surface analysis - A new look at old data: Contribution of the Department of Geology, Univ. Western Ontario, Canada, No. 119, 25 p. Swann, D. H., 1968, A summary geologic history of the Illinois Basin, Map "Structure at top Trenton," p. 12, in D . N. Miller, gen. ed., 1968, Geology and petroleum production of the Illinois Basin, a symposium, 111. and Ind.-Ky. Geol. Soc: Schulze Printing Co., Evansville, Ind. van Poollen, H. K., 1961, Status of drill-stem testing techniques and analysis: Jour. Petroleum Technology, v. XIII, no. 4, p. 333-339. Warner, D. L., 1965, Deep-well injection of liquid wastes: Public Health Service Publ. 999-WP-21, U.S. Dept. Health, Education and Welfare, 55 p. Willman, H. B. , and J. N. Payne, 1942, Geology and mineral resources of the Marseilles, Ottawa, and Streator Quadrangles: Illinois Geol. Survey Bull. 66, 388 p. HYDRODYNAMICS IN DEEP AQUIFERS 51 Wither spoon, P. A., I. Javandel, S. P. Newman, and R. A. Freeze, 1967, In- terpretation of aquifer gas storage conditions from water pumping tests: Am. Gas Assn., New York, 273 p. APPENDIX 1: CALCULATION OF H 3 " 00 I. Calculation of H ' from Water-Level Observations If a well contains fresh water, the observed virgin equilibrium water level in the well, with respect to sea level, is the value H that we desire. If the well contains water whose density differs appreciably from that of fresh water, we must apply a correction to the observed water level in order to obtain H * .If the water in the aquifer under consideration has the same density throughout, this correction is fairly straightforward. When the well has been swabbed or pumped until the composition of the produced water is constant, one can be reasonably certain that the hole is filled with water whose composition is constant throughout the depth of the hole and whose density is known. On the other hand, if the water in the aquifer is stratified because its density varies with depth, the picture is not so simple. With a stratified system the composition of the produced water depends, in a complex way, upon the vari- ation of water density with elevation, the horizontal and vertical permeability distribution within the rock, and the rate and duration of pumping. Even though the well is swabbed or pumped until the composition of the produced water is fairly constant, small variations in the density of the water column can introduce spurious effects. For example, if the water in 2, 000 feet of the water column has a relative density differing from that of the rest of the column by 0.005, an uncertainty of 10 feet in head is introduced, depending upon which part of the column is available for analysis. We should also note that for a stratified system, even if the water col- umn in the well has a uniform density whose value is known accurately, the value H * that is calculated applies only for the topmost level in the well that is open to flow; generally this is at the top of the perforations. When a stratified aquifer is pumped, lighter water cones down into the perforated zone while heavier water cones upward to a lesser degree. Usually the density of the water in the hole below the top of the perforations is not known; therefore, we have no way of calculating h • for points below the top of the perforations. In cases where the density of the water in the aquifer is known accurately as a function of depth, we can calculate H-^-^O a t various depths. In a stratified system, then, we can determine h 1 ' 00 for a single level in a given well. But in general we may not be able to determine, from water-level measurements, the head or the potential for other levels in the aquifer. The following diagrams illustrate the treatment needed for correcting water- level observations to obtain H^-00 for various cases: A. Aquifer contains fresh water. Well is swabbed or pumped until produced water has relative density 1.00 . No correction is needed. B. Aquifer contains water having relative density p until produced water has relative density p . Well is swabbed or pumped t Well-head elevation S.L Depth to point of observation in aquifer (top perforations, etc.) Length of observed water column, L obs . _\k f obs , Observed water level A Corrected water level 1.00 I Length of equivalent fresh- water column, L eq. L = L , xp eq. obs. obs. obs. r This equation gives H • ■ at the top of the perforations. At a depth AZ lower than this point, H 1 • 00 [ S larger by the amount (p - 1) AZ. C. Aquifer contains water whose density varies with depth. Well is swabbed S.L or pumped until produced water has constant relative density P r * Well-head elevation Observed A 7T obs {uoser water level f { Corrected water level 1.00 Depth to point of observation Length of observed water column^ L obs . Length of equivalent fresh- water column, L 1 eq, eq = L u x P obs. r c H 1 ' 00 ^ obs obs. 'c This equation gives H ' at the top of the perforations. In general, H ' can- not be determined for other levels in the aquifer. Even though the composition of the water column in the well is the same at various depths, the density will vary somewhat because of the increase in tem- perature with depth. No attempt was made here to correct for this temperature effect; thus small errors may be introduced in the absolute values calculated for H • for different drill holes. However, for a given depth, the temperature correction should be about the same for different wells; thus the fact that the temperature correction has been ignored should not appreciably change the relative values of H^'^O in wells drilled to about the same depth. For wells having different depths, sample calculations were made on the assumption of reasonable values of the temperature gradient; these calculations indicated that in the northern part of the state neglect of the temperature correction could in- troduce differences in H of only a few feet at most. The uncertainties in the water-level data are probably considerably greater than any error that might be introduced by neglecting the temperature correction for the water column. The water level in a well changes as the barometric pressure changes. The level is also affected by earth tides (Witherspoon et al., 1967, p. 2). Be- cause of lack of information, no correction was made here for these effects. Since these barometric and tidal effects are usually about one foot or less, the error caused by neglecting them is not significant. Analysts generally report specific gravity of the waters that they analyze Often the base for the specific gravity determination is not specified. In this report, p , the water density relative to fresh water, was considered to be equal to the reported specific gravity. This procedure could result in small errors in the absolute value of p but should have little effect on the relative values of p over a reservoir where all samples were analyzed in the same manner. II. Calculation of H * from Drill-Stem Test Results For many of the wells studied here, the complete service-company re- ports on drill-stem tests (DST) were available. In a few cases we had only the reports of pressures observed in the DST, usually the initial closed-in pressure (ICIP) and the final closed-in pressure (FCIP) . In order to determine h^*^^ from drill-stem results, one must know the reservoir pressure at one elevation in the aquifer. If ICIP and FCIP have the same value, this value is probably a good estimate of the reservoir pressure. If similar heads are obtained from top and bottom gauge readings, gauge readings are probably reliable since both gauges are not likely to be in error by the same amount. Also, sometimes a check on the accuracy of the gauge can be made if the mud weight is known; the hydrostatic mud pressure, calculated from mud weight and gauge depth, can be compared with the observed mud pressure. The amount of liquid fill-up during the DST gives further evidence of the quality of the reservoir pressure data obtained in the test. Small fill-up is an indication of low permeability; therefore, shut-in pressures after the flow period may be unreliable. In this case the ICIP may be the most reliable value. Large fill-up is an indication of high permeability. Even when the ICIP and FCIP differ somewhat, a good estimate of the reservoir pressure often can be made by plot- ting log [ (t + 9)/6 ] vs. shut-in pressure and extrapolating to log [ (t + 9)/8] = (Dolanetal., 1957; van Poollen, 1961). In the present study, after the best estimate of reservoir pressure had been made from the DST data, the pressure, in pounds per square inch, was con- verted to equivalent feet of fresh-water head by multiplying by the factor 2 .31 . That is, equivalent feet of fresh water = 2.31 x reservoir pressure (psig) . ;:.[,. Well- head elevation * 4\ 1.00 H ±__ Gauge Equivalent feet of depth fresh-water head (2.31 x reservoir N ' pressure, psig) 1 j|l «00 - elevation + [(equivalent feet of fresh-water head) — (gauge depth) ] Drill- stem test pressures are generally reported as gauge pressures, psig. Values of H* • O'O calculated in the manner described above, using psig, can be compared directly with values of H* «00 derived from water-level observa- tions. In a few cases absolute reservoir pressures were reported (psia) . In each of these cases one atmosphere, 14.7 psi, was subtracted from the reported psia reading to give psig; this psig value was then used to calculate a value of H^ -00 that would be consistent with the values of H 1 '^0 that were derived from the re- sults of water-level and DST observations. In a few instances estimates of H 1 -00 were made from the fill-up data given for DST tests. These estimates generally were of questionable validity because of uncertainties about whether or not equilibrium was reached as well as uncertainty about the density of the liquids recovered in the DST. They did serve to give a lower limit of H 1 m ®Q because we had some assurance that H^ -00 was at least as high as the value calculated from the fill-up data. APPENDIX 2: DATA TABLE 1 - HYDRODYNAMIC DATA Reservo Ancona No. 111. Gas Fordyce No. 1 Livingston 33,30N,3E Mt. S. No. 111. Gas Krischel No. 2 Livingston 24,30N,2E Mt. S. No. 111. Gas No. 111. Gas Scheuer No. 1 Barr No. 1 La Salle La Salle 14,30N,2E 22,30N,2E Mt. s. s. Brookville Nat'l. Gas Pipeline Ogle 41N.7E Eau s. CI Crescent City No. 111. Gas Iroquois 26-27N,13W Mt. Mt. s. s. "A' "B' Taden No. 209 Iroquois 11,26N,13W Mt. s. "A' Taden No. 201 Iroquois 11,26N,13W Mt. s. '•B' Dale Texaco Cuppy No. 1 Hamilton 6,6S,7E Eau CI 640 NIG Std. Top perfs 663 NIG Std. Top perfs. 667 NIG Std. Top perfs. 671 NIG Std. Top perfs. 654 NIG Std. Top perfs. 656 NIG Std. Top perfs. 3400 3580 3971 Top ga. 11,793 Bottom ga. 11,812 -2746 -2924 -3323 -2954 -11,400 1.011 18,448 1.061 1.068 1.061 1.128 212,179 Erp Nelson-Erp & Stroh Erp No. 1 Ford 19,24N,7E Mt. S. 828 G.L. Top Mt. S. 4220 -3392 1.039 est. 57,600 Hennepin Jones & Laughlin Waste-dispos- al well No. 1 Putnam 3,32N,2W Mt. S. 527 K.B. Top Mt. S. 3109 -2 582 1.041 61,600 Herscher Nat'l. Gas Pipeline Karcher No. 6 Kankakee 32,30N,10E Mt. S. 678 K.B. Top Mt. S. 2439 -1761 1.013 18,940 Herscher NW Nat'l. Gas Pipeline P. Cook No. 1 Kankakee 3,30N,9E Mt. S. 622 K.B. Top Mt. S. 2204 -1582 1.004 9362 Hudson No. 111. Gas Schlosser No. 1 McLean 32,25N,3E Mt. S. 776 NIG Std. Top perfs. 3956 -3180 1.053 74,450 Lake Bloomington No. 111. Gas J. Anderson No. 1 McLean 31,26N,3E Mt. s. 727 NIG Std. Top perfs. 3608 -2881 1.045 59,650 No. 111. Gas Furrow No. 4 McLean 31,26N,3E Eau CI. 748 NIG Std. Top perfs. 3276 -2 528 1.022 Lamb Peoples Gas Lamb No. 1 De Witt 1,20N,4E Mt. s. 732 Orbit- Top perfs. 4570 -3834 1.074 107,115 Lexington No. 111. Gas No. 111. Gas No. 111. Gas No. 111. Gas No. 111. Gas Pyne No. 1 Smith No. 1 Moore No. 1 Cook No. 1 McLean McLean McLean McLean McLean 14,25N,3E 20,25N,4E 22,25N,3E 14,25N,3E Mt. Mt. Mt. Mt. Mt. s. s. s. s. s. 742 746 781 728 valve NIG Std. NIG Std. NIG Std. NIG Std. Top perfs. Top perfs. Top perfs. Top perfs. 3710 3752-3772 3857-3943 3908-3994 3726-3762 -2968 -3010 -3111 -3127 -2998 1.045 1.052 1.051 1.050 1.051 65,220 65,220 64,480 68,460 65,460 Louden Humble Weaber-Horn No. 1 Fayette 28,8N,3E Mt. s. 538 K.B. Top ga. 7978 -7440 M.ilion.f-1 Peoples Gas A. G. Hunt No. 5 Fee No. 1 Champaign 17,21N,7E Mt. s. 739 G.L. Top perfs. 3942 -3203 1.059 90,000 Peoples Gas Champaign 9,21N,7E Mt. s. 742 G.L. Top perfs. 3931-4010 -3189 1.061 82,600 Momence Momence Kankakee 24,31N,13E Mt. s. 628 G.L. T.D. 2800 -2172 1.025 38,000 Pecatonica Cen1 .ill. Elec. & Gas Wright No. 202 Winnebago 2,26N,10E ' Lights Eau ville" CI. 861 G.L. Top perfs. 820 + 41 1.00 Pontiac '1... 1 J 1 . ',.1K Fienhold No. 1 Fienhold No. 4 Livingston 33,28N,6E Mt. s. 732 NIG Std. Top perfs. 3008 -2276 1.034 50,800 No. 111. Gas Livingston 33,28N,6E Eau CI. 713 K.B. Top perfs. 2659 -1946 1.018 27,300 i . J.,- ob Mr.:.. 1'. lu.-l E. F. Kircheis No. S-l Madison 27,3N,6W Mt. s. 504 K.B. Top ga. Bottom ga. 4940 5013 -4436 -4509 1.07 est. 98,500 Salem I../.H '. R. S. Johnson No. ] Marion 6,1N,2E Mt. s. 541 K.B. Top ga. Bottom ga. 8892 8929 -8351 -8388 1.165 262,962 ihangha 1 iii. Powei Mobsrg No. I Warren 3.12N.1W Eau CI. 737 G.L. Top perfs. 2466 -1729 1.005 4100 i'. i.. Davil No. i Henry 30,16N,1E Mt. G.L. s. — grount 793 leve G.L. L; K.B. - Top ga. kelly bushing 2636 -1843 1.004 5900 »NIG ■"!. Northern 1 1 linoi Gas Standard (= 5 :. I...-I .iliMv f'.us I UK I'lUMtfe) ■'■ ' I i n. 'I I.-,, .1 I ., I„ 1 I,,' rnti.'.l r.< I i.ihli. v.i In AND RESULTS, TABLES 1- 7 ILLINOIS BASIN AND SURROUNDING AREA: MT. SIMON Water-level measurements pressure, pressure bomb (psig) Drill-stem tests „1.00»* Remarks ICIP (psig) FCIP (psig) Pressure at --(psig) Equiv. ft (2.31 x psig) Observed water level, S.L. (ft) Length of observed column (L obs ' Length of equiv. fresh- level observa- tion reser- From drill- Top ga. ga. Top ga. Bottom ga. Top ga- Bottom ga. Ft Derived Top ga. ga. from 17,900 to 25,800 3840 34S9 1768 1591 13,490 Extrap. 11,769 ICIP 5840 13,490 Extrap. press. 12,236 Mud Observed pressur 2384 2415 1045 2220 2229 976 3707 3903 3424 3083 3578 3151 1565 (at -2' S.L.) 4296 4614 Reser press Reser press 3615 Reserv press. H ' influenced by previous gas injection at Herscher H 1.00 ran g es f rom 72 i to 736 H 1 - 00 ranges from 695 3540 3647 3664 3534 3724 3833 3847 3714 8468 Extrap. press . 3927 Reserv. press. interval in well 2852 2949 1335 2446 2490 2153 2151 505 2348 (DST recovery) 2360 2357 2210 2210 3707 3642 4050 4973 FCIP 4080 9356 942 5 Extrap . press. Extrap . press. 2472 FCIP 631 514 (DST re- covery) H ' calculated from extrapolated pressure 1037 Ave. H 1 - 00 = 1021 (continued on the following pages' Table 1, Reservoir project Company Well Locat St rati graphic- Well-head Observa- point Depth point (ft) observa- point Produced Ft Refer- point* water County Sec, T.,R. P TDS (mg/1) L L I N I S continued Jensen Otto Swensen No. 1 La Salle N D I A N A Shaw No. 1 Douglas 1,36N,SE 32,3SN,1E 36,16N,8E Mt. S. 35, IS, 10W Eau CI. 15,13N,8W Mt. S. 9,39N,9E Mt. S. 26,29N,3W Eau CI. 659 G.L. Top perfs. 3464-3470 683 NIG Std. 14,37N,9W Mt. S. 608 Mt. S. 29,37N,8W Mt. S. Mt. S. 600 Mt. S. Mt. S. Eau CI. 2S,37N,7W Eau CI. 4 615 Mt. S. Mt. S. Eau CI. Eau CI. 28,37N,6W Eau Mt. CI. i 62 5 Mt. s. 21,34N,3E Mt. S. 789 Eau CI. 789 Top ga. Top ga. Top ga. K.B. DST inter- val DST inter- val G.L. Top ga. Bottom ga. G.L. Top ga. Bottom ga. G.L. Top ga. Bottom ga. Top ga. Bottom ga . 3464-3470 -2805 1.047 67,000 1421 -738 1.00 2330 2440 3995 -3316 1.081 est. 113,144 4038 -3359 1.09 4040 -3361 4046-4060 -3380 1.073 est. 103,000 4063-4085 -3397 1.090" 128, 00C 27S0 -2084 1.013 20,000 3870-3895 2582-2600 2469-2491 3316-3333 3793-3813 2420 2109-2142 2160-4259 3416 1802 162 5 1865-2918 -1466 -1766 -2266 -3166 -3262 -1974 -1869 -2 716 -3193 -1820 -1509 -2801 -1187 -1010 2708 2293 2308 2387 2474 2639 -1919 -1607 -1622 -1701 -1788 -1953 -2040 1.00 1.003 1.02 1.07 1.090 123,000 1.016 20,100 1.010 13,200 1.071 97,800 1.092 124,000 1.100 ~ 34, 000 (ppm CI) Newport Royal Center No. Ind. No.S-lll-2 Pub. Serv. No. Ind. No.S-111-2 Pub. Serv. No. Ind. No.S-94-2 Pub. Serv. No. Ind. No.S-95 Pub . ",i r v. :i... I,,.|. No.S-84 Pub. Serv, No. Ind. No.S-76 Pub. Serv. No. [nd. No.S-55 pub. B«rv, Cass Cass C-inu 9,16N,9W Mt. S. 14.28N.1W Mt. S. "A' Mt. S. "B' Mt. S. "basement" 20,29N,1E Mt. S. 20,29N,1E Mt. S. 30,29N,1E Eau CI. 30.29N.1E 14,28N,1W Galesville- Mt . S. Mt. S. "B' 17.28N.1W Mt. S. "[!' 17,28N,1W Mt . S. "A" 1.148 234,700 val Top perfs. G.L. Top ga. Bottom ga. 2913 -2173 G.L. Top ga. 2784 -2044 Center ga. 2823 -2083 G.L. Top ga. 2581 -1833 Bottom ga. 2605 -1857 G.L. Top perfs. 2164 -1414 G.L. Tup pel i::. 2906 -2174 G.L. Top perfs. 2958 -2209 G.L. Top perfs . 2958 -2213 .B. - kolly bushing. Water -level measu ements Reservoir pressure, (psig) Drill stem tests 1.00* ♦ Remarks ICIP (psig) FCIP (psig) Pressure at * ~(psig) Equiv. ft fresh water (2.31 x psig) Observed S.L.' (ft) Length of observed column (L Qbs ) Length of equiv. fresh- """ L o ° bs U T level tion "ir *£ drill- n test Top ga. ga. Top ga. Bottom ga. Top ga- ga. Ft Derived Top ga. Bottom ga. 577 (DST 2770 recovery) 3047 -592 (DST 1323 recovery) 1323 1197 (DST 410 431 319 (DST 2020 recovery) 2121 367 (DST 2320 recovery) 2436 4114 Ex trap, press. 3280 Extrap. press. 2356 Extrap. press. 2051 Extrap. press. 3269 FCIP 1587 FCIP 1418 FCIP 2499 FCIP 2171 Extrap. press . 2264 Extrap. 2268 Extrap. press . 2356 Extrap. press . 2541 Extrap. 2633 Extrap. -1156 (DST recovery) 420 (DST recovery) (DST recovery) Data from Gr 1966, table al = 2099 feet Note large open interval Contaminated sample ? 55 2495 (DST recovery) 2682 44 (DST ] 1500 ecovery) 1597 13 (DST 1020 ecovery) 1076 135 1849 1973 150 2624 2787 320 2829 3004 =82 2795 2982 1135 1142 1048 1044 1061 1056 2638 FCIP 2412 FCIP 2439 FCIP -447 (DST recovery) Remark for S-8S and S-94 also applies here (continued on the following pages Table 1, - HYDRODYNAMIC DATA - Reservoir Company Well Locat Stratigraphic Well-head Observa- point Depth observa- point (ft) tion point Produced Ft Refer- pointr* P TDS (mg/l) County Sec, T.,R. Boyd Holland No. Ind. No.S-85 Pub. Serv. No. Ind. No.S-94 Pub. Serv. No. Ind. No.S-79 Pub. Serv. No. Ind. No.S-99 Pub. Serv. Consumers Brine dis Power posal No Holland Suco Disposal Color Co. well No. Cass Fulton Fulton Fulton 12,28N,1W 30,29N,1E 30,29N,1E 30,29N,1E 31,4N,15E 30,SN,1SW Cairo Nat'l. Gas Pipeline Louisa Columbia C ty Nat'l. Gas Pipeline Louisa Redfield No. Nat'l. Gas Hummel No . 1 Dallas 18,79N,28W Vincent No. Nat'l. Gas Peterson No. 1 Webster 10,90N,27W Wapello Nat'l. Gas Pipeline Louisa Dundee-Detroit 623 River Detroit River Trempealeau- Franconia- Eau CI. Eau Cl.- Mt. S. Dresbach (Cambrian) 1050 1144 Top perfs. 2904 -2167 1.064 Top perfs. 2785 -2037 1.073 Top perfs. 2898 -2149 1.068 Top perfs. 2510 -1761 Perfs . Perfs. Top ga. Top ga. Perfs . kelly bushing. 4496-4627 -3888 to -4019 1.191 318,500 1680-1893 1.165 235,950 1928-1940 4615-4805 153,450 1.18 160,000 (Chlorides) 4866-5894 1.16 155,000 (Chlorides) 1.227 30,000 (ppm Ca) - -1650 1.007 11,000 1650 1.007 esrt. 10,000 2731 -1681 1.00 1782 2160 -1016 1.009 est. 13,188 ~ -1650 1.007 est. continued Water -level measurements Reservoir pressure, pressure (psig) Drill-stem tests H 1 ' 00 * Remarks ICIP (psig) FCIP (psig) Pressure at - »(psig) Equiv. ft fresh water (2.31 x psig) Observed S.L. (ft) Length of Length of water column level tion From reser- From drill- stem test Top ga- ga. ga. Bottom ga. Top ga. Bottom ga- Ft Derived from Top ga. Bottom ga. 440 2607 440 2 589 392 2153 Other water-level & pressure data indicate flow, which is probably toward the north or northeast 3240 (DST recovery) Gauge assumed to be top of DST interval 61 2311 2327 63 2313 2329 64 2 545 2545 2 564 FCIP 1940 ICIP TABLE 2 - HYDRO DYNAMIC DATA - Reservoi r project Well Location Strati graphic Well-head elevation Observa- point Depth observa- (ft) observa- tion Produced « Refer- water County t.,r! P TDS (mg/l) ILLINOIS Ancona No. 111. Gas Fordyce No. 3 Livingst No. 111. Gas La Salle Brookville Nat'l. Gas Pipeline Ogle Clay City Union of California Cisne Comm. No. 1 Wayne Crescent City No. 111. Gas Iroquois Dale Texaco Cuppy No. 1 Hamilton Nettle Nettle No. 1 33,30N,3E Galesville 30N,2E Galesville 41N,7E Galesville 26,27N,13W Galesville 6,6S,7E Potosi 33, IN, 10W Knox Franconia Lexingto Mahomet Pontiac Shanghai South Troy Grove Am. Ind. Waste Dispos- al Syst., Inc Waste-dis- posal well No. 1 3,32N,2W Franconia- Ironton- Galesville Nat'l. Gas Pipeline Karcher No. 8 Kankakee 28,30N,10E Galesville Nat'l. Gas Pipeline P. i;ook No. G-l Kankakee 3,30N,9E Galesville No. 111. Gas Grimes No. 3 McLean 1,24N,2E Galesville No. 111. Gas Furrow No. 4 McLean 31,26N,3E Galesville No. 111. Gas Cook No. 2 McLean 14,25N,3E Galesville Peoples Gas Fee No. 3 Champaign 9,21N,7E Galesville Peoples Gas G. Webster No. 1 Champaign 17,21N,7E Galesville Central 111. Electric & Gas Wright No. 401 Winnebago 2,26N,10E Galesville Humble J.E. Pickel No. 1 Union 21,13S,2W Knox No. 111. Gas Fienhold No. 3 Livingston 33,28N,6E Galesville 111. Power Co. Anderson No. 1 Moberg No. 2 Warren Warren 7,12N,1W 3,12N,1W Galesville Franconia R. E. Davis E.A. South No. 1 Henry 30,16N,1E Ironton- Galesville No. 111. Gas Amfahr No. 3 La Salle 29,3SN,1E Galesville No. 111. Gas Weldon No. 9 La Salle 5,34N,1E Galesville Cabot Corp. Cabot No. 1 Douglas 31,16N,8E Knox U.S. Indus- trial Chem. USI dispos- al well No. 1 Douglas 31,16N,8E as Amgo & Botts Buck No. 2 Douglas 31,16N,8E Trempealeat 640 NIG Std. Top perfs . Top perfs. Top perfs. 1724 1708 -1084 -1045 1.00 1.00 3785 6658 504 K.B. Top ga. Bottom ga. 7734 7772 -7230 -7268 1.076 106,000 650 NIG Std. Top perfs. 2650 -2000 1.039 55,700 393 K.B. G.L. Top ga. Bottom ga . 9649 9663 1741-1760 2456-2548 -9256 -9270 -1275 -1990 1.135 519 R.B. Top ga. Bottom ga. 2290 -1771 -2179 15,000 676 G.L. Top Glsvl. 1757 -1081 1.006 2528 611 G.L. Top Glsvl. 2269 -1658 1.006 1435 795 NIG Std. Top perfs. 3287 -2492 1.005 7480 713 NIG Std. Top perfs. 2996 -2283 1.001 1955 743 NIG Std. Top perfs. 3157-3167 -2414 1.00 1410 758 K.B. Top perfs. 3272-3292 -2514 1.026 758 K.B. Top perfs. 3277-3297 -2519 1.026 37,000 862 G.L. Top Glsvl. 680 + 182 1.00 424 K.B. Top ga. Bottom ga. 5695 5792 -5271 -5368 1.073 est. 101,000 711 K.B. Top perfs. 2457 -1746 1.00 1300 701 G.L. Top Glsvl. 2118 -1417 1.00 1235 700 G.L. Top Franconia 1980 -1280 1.00 480 793 G.L. Top ga. 2290 -1497 1.002 4400 691 NIG Std. Top Glsvl. G.L. Knox K.B. Top Knox K.B. Top ga. Waverly Panhandle Eastern Criswell No. 1-16 Morgan 16,13N,8W Galesville INDIANA Gary U.S. Steel Waste-dispos- Lake 29,37N,8W Galesville Lake of the Woods, East No. Ind. Pub. Serv. II. Ames No. 1 Marshall 21,34N,3E Galesville (some Eau CI.) Royal Center No. Ind. Pub. Serv. No. Ind. Pub. Serv. No.S-95 N0.4-S-99 Fulton Fulton 30,29N,1E 30,29N,1E Galesville Galesville No. Ind. Pub. Serv. No.S-111-2 Fulton 20,29N,1E Galesville No. Ind. Pub erv, No.l-S-55 Cass 32,29N,1E Ironton- Galesville No. (rid. NoJ-S-55 Cass 32,29N,1E Franconia G.L. Pressu Gauge 1800-1830 -1200 1.004 i Top ga. 2385 -1596 1.028 Bottom ga. 2389 -1600 2200 -1451 1.045 64 est. Top ga. 2155 -1415 1.035 Center ga. 2169 -1429 1.035 Top ga. 2076 -1336 1.025 Bottom ga. 2120 -1380 Top ga. 2082 -1337 1.025 Bottom ga . 2114 -1369 Top ga. 2011 -1266 1.025 Pip . Monroe 21.21N.3E Knox 29,8N,1E Knox 30,5N,15W Fa ancon 1 1512-1520 2489 16,343 (ppm) calculated I D I i i , - ILLINOIS BASIN AND SURROUNDING AREA: IRONTON-GALESVILLE THROUGH KNOX Water -level measu ements pressure (psig) Drill -stem tests ..1.00** Remarks ICIP (Psig) FCIP (psig) Pressure at G --(psig) Equiv. ft fresh water (2.31 x psig) S.L.' (ft) Length of observed water Length of equiv. fresh- water column ^ x L obs.) level tion reser- pres- From ste drill- Top ga. ga Top ga. Bottom ga. Top ga. ga- « Deri ved from Top ga. liottom 140 5 (DST recovery) 240 (DST recovery) 3254 3506 3404 3325 3560 1552 1561 700 at -1100 2114 212 7 3003 3018 2793 2796 2926 2926 2872 2977 2947 3055 1285 t at -240K 8099 Extrap 8224 press . Extrap press. 9961 ICIP 10372 1663 Extrap press . 2407 2312 FCIP 2716 FCIP 1617 Reserv 2968 Reserv press. Ave. H = 913 f 1 '™ from ICIP J 1 - 00 c i from Extrap. press Ave. H ' = 539 1930 1794 443 1940 (DST recovery) 5962 FCIP 5983 FCIP Depth of pressu reading is unce 4770 (salty wa 4701 Reserv Density of water in well at time of W.L. observation is not known Hole contained fresh water at time W.L. was measured Water level calcu- lated from recovery in DST is question- able 2030 (DST recovery) 2125 FCIP 2139 FCIP 1820 covery) 163 1500 (DST recovery) 524 4000 1 water 4890 + 570' drilling fluid (DST TABLE 3 - HYDRODYNAMIC DATA - Reservoir Company Location Stratigraphy Well-head elevation point Depth point (ft) point Produced 't Refer- point* water County t.,r! P TDS (mg/l) ILLINOIS Ancona No. 111. Gas Clark No. 1 Livingston Montgomery 33,30N,3E 20,7N,2W St. P. St. P. 636 NIG Std. 617 D.F. Top perfs. Top perfs. 1.00 1205 1.009 13,900 Top perfs . Top ga. Ford Lamb-Walde Pecatonica Plymouth Pontiac Rodda Superior H.C. Ford et al. No. C-17 White 27,4S,14W St. P. 386 Peoples Gas Lamb No. 1 De Witt 1,20N,4E St. P. 732 Walden No. 1 De Witt 29,21N,4E St. P. 749 Carter J. Brauer No. 6-D Fayette 21,8N,3E St. P. & Knox 528 Peoples Gas A.G. Hunt No. 5 Champaign 16,21N,7E St. P. 755 Cent. 111. Elec. & Gas Gustafson No. 601 WB Winnebago 34,27N,10E St. P. 842 Marathon Lyon Hrs. No. CT-1 McDonough 19,4N,4W St. P. 616 No. 111. Gas F'ienhold No. 200 Livingston 28,28N,6E St. P. Magnolia M.T. Rodda No. 1 M.T. Rodda No. 1 Coles 4,UN,9E St. P. Glenwood 611 611 Fuel Texaco Orbit- Bottom ga. Top ga. Top perfs . Top perfs . Top perfs. Top St. P. Top St. P. Top ga. Bottom ga. Top ga. Top ga. Top ga. Bottom ga. Top ga. Bottom ga. Top ga. Bottom ga. 7628 7335 -7235 -6949 1540 169 5253 5224 2186 2837 2924 5220 -4642 -4613 -1376 -2333 -2420 -4679 1.14 199,000 1.005 3308 .003 1715-3134 Shanghai South Tuscola Moberg No. E.A. South No. 1 Debolt No. Warren Henry 3,12N,1W 30,16N,1E M I C Barry Keota Redfield Lake of the Woods, East Nat'l. Gas Pipeline Nat'l. Gas Pipeline No. Nat'l. Gas Koss No. 1 Waltrip No. 1 Municipal water well Douglas Champaign Douglas Douglas Barry Louisa Washing Dallas Webster 18,79N,28W 10,90N,27W St. P. St. P. St. P. St. P. St. P. G.L. Top perfs. 1506 G.L. Csg. seat 1640 G.L. Csg. seat 1519 Top St. P. Perfs. 4840 Perfs. Top ga. 1741 Top ga. 1235 Top ga. 1731 Bottom ga. 1754 1.004 7114 1.012 19,606 1.014 22,706 1568 1034 Jlty ~ 16, 900 (ppm CI) kelly bushing; G.L. - ground level. ILLINOIS BASIN AND SURROUNDING AREA: ST. PETER pressure, from pressure (psig) Drill-stem tests H i.oo»* Remarks ICIP (psig) FCIP (psig) Pressure at G --(psig) Equiv. ft fresh water (2-31 x psig) Observed S.L.' (ft) Length of (L o ^") Length of equiv. fresh- ^ "CbsT water- level tion reser- pres- From dri li- sten test Top ga- Bottom Top ga. Bottom ga. Top ga. Bottom ga. Ft Derived from Top ga. Bottom ga. 1650 1584 3659 1097 FCIP FCIP f Extrap. J. press. I^Top gaug FCIP FCIP Reported pressure be psia 514 2057 50u 2164 473 4400 537 1322 2450 (?) (DST fill-up) Poor DST. H i-U " is at least 486, prob- ably higher 71 4950 (DST recovery) 376.7 (depth ?) 2250 2200 848 FCIP 859 FCIP 511 5198 FCIP 5082 FCIP 1903 1910 FCIP 561 (DST recovery) FCIP 2841 2924 FCIP FCIP 417 (DST recovery) 5278 5318 Extrap. press . 618 (DST recovery) Ave. H - 537 Ave. H^OzSOb Ave. H = 598 1306 1311 1421 1438 1324 1343 igh calcium content 1617 FCIP 1074 FCIP 1444 FCIP 1467 FCIP +- CD Q^ -P tf > t) CD CJ d 93 TJ o O En Sh PL, N -P ft o a p o ■H fl P -P cti ft > H ft P 0) 0) ft P •H 1 S •H P CJ tfl -H ?H fl P ft CQ d U bO ft En a '. o o ■H CD p CQ d o o fl S P § o o I a H H CD ES 1 a> o o ft a c 01 0) « LA CO OO OO vo CO r— CM la j- o o o OO H o on o ro o o o o o o H o o o o o J- On 00 VO C— CM CO rH VO o LA O H VO LA ON O o\ o OO CM CO CM la CO -=r VO t— > bO CM H EH ,q d fl •H 51 o C1J > (1) rn a p u M O ^ CO <1> 01 Sh fl) w Tl Ct) r* < LA y> fl fl) b -H- H fl) (1) ft ft CM < A ft PI (i) O d H C5 h) co o 6 o rl S s p H H •H CQ O £ " " co O Tj On H 3 CM oo O ON o bO LA On t- O CM 00 ft O ft d id ft O o O ft o EH o VO VO VO VO VO VO CO CM CO VO VO VO V Ti !h () ft CD P CD PI •H pt !* ^ H cfl cti d CD & ci fl ft m rn r/> d ft H H o H TJ ^ PI Sh p ^H O O O ro CD ft (Si S a P S °a S^ * *" „ " ft (j <) ft ft C) H u CJ u u o CD CM ft ft H 1 H H -d H •H •H H •H S • O o 8 ^1 o O O (0 O O § S •H •H H : • •H «.: rl (1) '•: ft ■ > : ', fl d CT p Ti ^H CD o § o fl) H ^H ft >ft 1 6J ft H H i c i: „ •H o --i ^ ft a« CD ft -d TJ CD ol ro B ft •H 08 P TABLE 5 - HEAD AVAILABLE TO CAUSE FLOW FROM MT. SIMON (MT. S.) TO ST. PETER (ST. P.) Location 1.00 Mt. S. 1.00 H St. P. ^Mt. S. Z Mt. S. z st. P. AH 1 " 00 ■ [( ^Mt.S. -1)AZ] Lake of the 618 502 1.10 -2,193 -9^2 -9 Woods South 629 512 l.ooU -1.8U3 -h91 112 Shanghai 631 (Eau 01.) 512 1.005 (Eau CI.) -1,729 (Eau CI. ) -3^2 112 Ancona 6^0 ^99 1.013 -1,538 +288 117 Crescent City 715 505 1.06l -2,7^6 -569 133 Mahomet 756 5U1 1.062 -3,203 -785 65 Lamb 776 525 1.01k -3,83U -1,539 81 Tuscola 756 U89 1.082 -3,332 -802 60 Louden 1,028 U86 1.1U5 (interp. ) -7,^53 -3,927 31 St. Jacob 567 506 1.07 -M51 -2,3^3 -87 Salem 1,021 598 1.165 -8,367 -^,695 -183 P r St. P. AH 1 .00 - [( ^st.p. -1)AZ] Salem 1.075 1U8 A7 r ATT 1.00 / [AH " ( ^st. p.- L)AZ] 1 (^)in eq. (P Mt. S. r St. P, TABLE 6 - HEAD AVAILABLE TO CAUSE FLOW FROM MT. SIMON (MT. S.) TO IRONTON-GALESVILLE (GLSVL.) Location 1.00 H Mt. S. 1.00 Glsvl. ^Mt. S. Z Mt. S. Z Glsvl. AU 1.00 . AH minus [( ^Mt. S." 1)AZ] Pecatonica 686 (Eau CI.) 716 1.00 (Eau 01.) + 1+1 (Eau CI.) +182 -30 Brookville 61+8 682 1.00 -31+ South 629 513 1.001+ -1,81+3 -1,1+97 115 Shanghai 631 (Eau CI.) 513 1.005 (Eau CI.) -1,729 (Eau CI.) -1,1+17 116 Troy Grove 6U5 595 1.00 -738 -227 50 Ancona 61+0 k96 1.011 -1,538 -1,081+ 139 Herscher 65I+ 1+80 1.013- -l,76l -1,0 81 165 Pontiac 6T3 515 1.03U -2,276 -1,71+6 1U0 Crescent City 715 505 1.06l -2,71+6 -2,000 165 Lake Bloomington 697 513 1.01+5 -2,881 -2,283 157 Lexington llh 512 1.052 -3,010 -2,1+lU 171 Mahomet 1% 536 1.062 -3,203 -2,519 178 Hudson 723 527 1.053 -3,180 -2,1+92 160 Lake of the Woods 618 529 1.10 -2,193 -1,596 29 Royal Center 539* 585** 1+9 8 1+98 1.065* 1.070** -2,01+1+ -2,11+0 -1,336 -1,336 -5 + 31 *Top of Mt. Simon. **Average of 6 values near top of Mt. Simon. TABLE T - HEAD AVAILABLE TO CAUSE FLOW FROM IRONTON-GALESVILLE (GLSVL.) TO ST. PETER (ST. P.) Location 1.00 Glsvl. 1.00 H St. P. AH 1 ' 00 [AH - ( ^Glsvl.- l)AZ] * Pecatonica 716 735 -19 Shanghai 513 512 +1 Ancona h96 1+99 -3 Pontiac 515 511 +4 Crescent Ci ty 505 505 Mahomet 536 4.51 + 85 South 513 512 +1 *For Crescent City, £> "Glsvl. For Mahomet , p Glsvl. = 1.039, AZ = 1,431. 1.026, AZ = 1,734. For S outh , p Glsvl. 1.002, AZ = 1,000. -19 +1 -3 +h -56 +40 -1 ILLINOIS STATE GEOLOGICAL SURVEY Urbana, Illinois 61801 FULL TIME STAFF March 16, 1972 JOHN C. FRYE, Ph.D., D.Sc, Chief Hubert E. Risser, Ph.D., Assistant Chief (on leave) G. R. Eadie, M.S., E.M, Administrative Engineer Helen E. McMorri: Velda A. Millard, Secretary to the Chief Fiscal Assistant to the Chief M. L. Thompson, (on leave) Ph.D, GEOLOGICAL GROUP Jack A. Simon, M.S., Principal Geologist Principal Research Geologist R. E. Bergstrom, Ph.D. Frances H. Alsterlund, A.B., Research Associate Coordinator, Environmental Geology COAL M. E. Hopkins, Ph.D., Geologist and Head Harold J. Gluskoter, Ph.D., Geologist William H. Smith, M.S., Geologist Neely-H. Bostick, Ph.D., Associate Geologist Kenneth E. Clegg, M.S., Associate Geologist Heinz H. Damberger, D.Sc, Associate Geologist Russel A. Peppers, Ph.D., Associate Geologist Roger B. Nance, M.S., Assistant Geologist George J. Allgaier, B.A., Jr. Assistant Geologist Kenneth R. Cope, B.S., Research Assistant Christine M. Pischl, B.S., Research Assistant OIL AND GAS Donald C. Bond, Ph.D., Head Lindell H. Van Dyke, M.S., Geologist Hubert M. Bristol, M.S., Associate Geologist Thomas F. Lawry, B.S., Associate Petroleum Engineer R. F. Mast, M.S., Associate Petroleum Engineer Wayne F. Meents, Associate Geological Engineer David L. Stevenson, M.S., Associate Geologist Richard H. Howard, M.S., Assistant Geologist Jacob Van Den Berg, M.S., Assistant Geologist Nancy J. Harper, Technical Assistant Marjorie E. Melton, Technical Assistant ENGINEERING GEOLOGY AND TOPOGRAPHIC MAPPING W. Calhoun Smith, Ph.D., Geologist in charge Paul B. DuMontelle, M.S., Associate Geologist CLAY RESOURCES AND CLAY MINERAL TECHNOLOGY W. Arthur White, Ph.D., Geologist and Head Bruce F. Bohor, Ph.D., Associate Geologist Cheryl W. Adkisson, B.S., Research Assistant Barbara E. Peterson, B.S., Technical Assistant GEOLOGICAL RECORDS Vivian Gordon, Head Hannah Kistler, Supervisory Assistant Diane L. Heath, B.A., Research Assistant Elizabeth A. Anderson, Technical Assistant Betty C. Cox, Technical Assistant Joann L. Graves, Technical Assistant Coradel R. Little, A.B., Technical Assistant Connie L. Maske, B.A., Technical Assistant Elizabeth Speer, Technical Assistant GROUND-WATER GEOLOGY AND GEOPHYSICAL EXPLORATION Robert E. Bergstrom, Ph.D., Geologist and Head Merlyn B. Buhle, M.S., Geologist John P. Kempton, Ph.D., Geologist Keros Cartwright, M.S., Associate Geologist George M. Hughes, Ph.D., Associate Geologist Leon R. Follmer, Ph.D., Assistant Geologist Manoutchehr Heidari, Ph.D., Assistant Engineer Paul C. Heigold, Ph.D., Assistant Geophysicist Kemal Piskin, M.S., Assistant Geologist Philip C. Reed, A.B., Assistant Geologist Frank B. Sherman, Jr., M.S., Assistant Geologist Ross D. Brower, M.S., Jr. Assistant Geologist Jean I . Larsen, M.A., Jr. Assistant Geologist Joan E. Buehler, A.M., Research Assistant George P. Zielinski, Technical Assistant STRATIGRAPHY AND AREAL GEOLOGY Charles Collinson, Ph.D., Geologist and Head Elwood Atherton, Ph.D., Geologist T. C. Buschbach, Ph.D., Geologist Herbert D. Glass, Ph.D., Geologist Lois S. Kent, Ph.D., Associate Geologist Jerry A. Lineback, Ph.D., Associate Geologist David L. Gross, Ph.D., Assistant Geologist AlanM. Jacobs, Ph.D., Assistant Geologist Michael L. Sargent, M.S., Assistant Geologist Matthew J . Avcin, M.S., Research Assistant Julia C. Badal, B.S., Research Assistant James. E. Rogers, M.S., Research Assistant Margaret L. Whaley, B.S., Research Assistant Mildred R. Newhouse, Technical Assistant INDUSTRIAL MINERALS James C. Bradbury, Ph.D., Geologist and Head James W. Baxter, Ph.D., Geologist Richard D. Harvey, Ph.D., Geologist Norman C. Hester, Ph.D., Assistant Geologist George M. Wilson, M.S., Assistant Geologist GEOLOGICAL SAMPLES LIBRARY Robert W. Frame, Superintendent J. Stanton Bonwell, Supervisory Assistant Charles J. Zelinsky, Supervisory Assistant Patricia L. Johnson, Technical Assistant Harris R. McKinney, Technical Assistant Eugene W. Meier, Technical Assistant G. Robert Yohe, Ph.D. Thelma J. Chapman, B , Senior Chemist A., Research Assistant CH EMI CAL GROUP Glenn C. Finger, Ph.D., Principal Chemist N. F. Shimp, Ph.D., Coordinator, Environmental Research Anita E. Bergman, B.S., Technical Assistant MINERALS ENGINEERING R. J. Helfinstine, M.S., Mechanical Engineer and Head H. P. Ehrlinger III, M.S., E.M., Assoc. Minerals Engineer John M . Masters, M.S., Assistant Mineralogist Lee D. Arnold, B.S., Research Assistant Walter E. Cooper, Technical Associate Robert M. Fairfield, Supervisory Assistant Jlmmie D. Cooper, Technical Assistant John P. McClellan, Technical Assistant (on leave) Edward A. Schaede, Technical Assistant (on leave) GEOCHEMISTRY G. C. Finger, Ph.D., Acting Head Donald R. Dickerson, Ph.D., Organic Chemist Josephus Thomas, Jr., Ph.D., Physical Chemist Richard H. Shiley, M.S., Associate Organic Chemist Robert R. Frost, Ph.D., Assistant Physical Chemist Ralph S. Boswell, Technical Assistant (Chemical Group continued on next page) CHEMICAL GROUP — Continued ANALYTICAL CHEMISTRY Neil F. Shimp, Ph.D., Chemist and Head Rodney R. Ruch, Ph.D., Chemist William J. Armon, M.S., Associate Chemist John A. Schleicher, B.S., Associate Chemist Larry R. Camp, B.S., Assistant Chemist Dennis D. Coleman, M.S., Assistant Chemist David B. Heck, B.S., Assistant Chemist L. R. Henderson, B.S., Assistant Chemist F. E. Joyce Frost, Ph.D., Assistant Chemist Lawrence B. Kohlenberger, B.S., Assistant Chemist John K. Kuhn, B.S., Assistant Chemist Patricia M. Santoliquido, S.B., Special Research Associate William C. Harfst, B.S., Special Research Assistant Joan D. Hauri, B.A., Special Research Assistant Paul E. Gardner, Technical Assistant George R. James, Technical Assistant W. L. Busch, A.] MINERAL ECONOMICS GROUP Hubert E. Risser, Ph.D., Principal Mineral Economist (on leave) Economic Analyst Robert L . Major, M.S., Assistant Mineral Economist Irma E. Samson, Clerk Typist II ADMINISTRATIVE GROUP George R. Eadie, M.S., E.M., Head Paula A. Manny, B.S., Research Assistant TECHNICAL RECORDS Miriam Hatch, Supervisor Carol E. Fiock, Technical Assistant Hester L. Nesmith, B.S., Technical Assistant PUBLICATIONS Betty M. Lynch, B.Ed., Technical Editor Mary Ann Noonan, A.M., Technical Editor Jane E. Busey, B.S., Assistant Technical Editor Dorothy Rae Weldon, Editorial Assistant Marie L. Martin, Geologic Draftsman Ilona Sandorfi, Assistant Geologic Draftsman Patricia A. Whelan, B.F.A., Asst. Geologic Draftsman William Dale Farris, Scientific Photographer Dorothy H. Huffman, Technical Assistant GENERAL SCIENTIFIC INFORMATION Peggy H. Schroeder, B.A., Research Assistant Bonnie L. Johnson, Technical Assistant FINANCIAL OFFICE Velda A. Millard, in charge Marjorie J. Hatch, Account Technician I Pauline Mitchell, Account Technician I Virginia C. Smith, B.S., Account Technician I CLERICAL SERVICES Nancy J. Hansen, Secretary I Hazel V. Orr, Clerk-Stenographer III Mary K. Rosalius, Clerk- Stenographer II Lucy Wagner, Clerk-Stenographer II Francie W. Doll, Clerk-Stenographer I Janette L. Hall, Clerk- Stenographer I Theresa J. Martin, Clerk- Stenographer I Edna M. Yeargin, Clerk-Stenographer I JoAnn L. Lynch, Clerk- Typist II Judith Ann Muse, Clerk-Typist II Pauline F. Tate, Clerk- Typist II SPECIAL TECHNICAL SERVICES Ernest R. Adair, Technical Assistant David B. Cooley, Administrative Assistant Wayne W. Nofftz, Distributions Supervisor Glenn G. Poor, Research Associate (on leave) Merle Ridgley, Instrument Specialist James E. Taylor, Automotive Mechanic Donovon M. Watkins, Technical Assistant EDUCATIONAL EXTENSION David L. Reinertsen, A.M., Geologist and Acting Head DwainJ. Berggren, M.A., Jr. Assistant Geologist Myrna M. Killey, B.A., Research Assistant LIBRARY Mary P. Krick, Linda K. Clem, M.S., B.S., Geological Librarian Assistant Librarian EMERITI J. S. Machin, Ph.D., Principal Chemist O. W. Rees, Ph.D., Principal Research Chemist W. H. Voskuil, Ph.D., Principal Mineral Economist A. H. Bell, Ph.D., Geologist George E. Ekblaw, Ph.D., Geologist H. W. Jackman, M.S.E., Chemical Engineer J. E. Lamar, B.S., Geologist L. D. McVicker, B.S., Chemist Enid Townley, M.S., Geologist Lester L. Whiting, M.S., Geologist H. B. Willman, Ph.D., Geologist Juanita Witters, M.S., Physicist RESEARCH AFFILIATES AND CONSULTANTS Richard C. Anderson, Ph.D., Augustana College W. F. Bradley, Ph.D., University of Texas David A. Castillon, M.A., Lincoln College John P. Ford, Ph.D., Eastern Illinois University Donald L. Graf, Ph.D., University of Illinois S. E. Harris, Jr., Ph.D., Southern Illinois University W. Hilton Johnson, Ph.D., University of Illinois Harry V. Leland, Ph.D., University of Illinois A. Byron Leonard, Ph.D., University of Kansas Lyle D. McGinnis, Ph.D., Northern Illinois University I. Edgar Odom, Ph.D., Northern Illinois University T. K. Searight, Ph.D., Illinois State University George W. White, Ph.D., University of Illinois Topographic mapping in cooperation with the United States Geological Survey. Illinois State Geological Survey Circular 470 72 p., 22 figs., 7 tables, 2 appendixes, 2000 cop., 1972 Urbana, Illinois 61801 Printed by Authority of State of Illinois, Ch . 127, IRS, Par. 58.25 CIRCULAR 470 ILLINOIS STATE GEOLOGICAL SURVEY URBANA, IL 61801