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Anderson County Oil and Gas

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Refineries and Pipe Lines

No refineries have been built in Anderson County. The oil enters trunk pipe lines that reach refineries in Missouri, Illinois and Indiana.

The Prairie Oil & Gas Company and the Sinclair Crude Oil Purchasing Company buy the oil from the producers. The former company was the original one in this district and its lines connect most of the leases. The Sinclair company takes oil from a few of the properties in the eastern end of the Bush City field and transports it to Centerville, in Linn County, where it enters a trunk line. The main lines of the Prairie Pipe Line Company which are laid through the county consist of one 8-inch and three 12-inch lines. A pump station at Greeley has a capacity of 189,000 barrels per day.

The Kansas Natural Gas Company and the J. B. Kirk Gas & Smelting Company are the chief purchasers of gas. The Kansas Natural has two 16-inch lines which extend north-south. They cross the southern boundary of the county about 2 miles southwest of Colony, extend to Colony, thence along the Santa Fe railway to Welda, from there to Garnett, and then pass straight north from Garnett across the Anderson-Franklin county line.

The J. B. Kirk Gas & Smelting Company supplies gas to a market made up principally of cement plants at Iola and Mildred, and the city of Iola. Its lines take gas from wells in the Colony-Welda district, from the field 3 miles west of Garnett, and from small pools on the eastern side of the county.

Future Possibilities of Anderson County

The conditions under which the oil and gas occur in Anderson County make an appraisal of its future possibilities rather uncertain. Probably they rest principally in the sands that have already given the most production.

A few scattered deposits of the 300-foot sand that will yield gas may be expected, chiefly in the northeastern quarter of the county, where this sand has been found most often.

The 600-foot sand, like the shallow one above it, has little potential worth. Up to this time only a very small percentage of the gas production has come from it. The short lives of the wells, which had original small volume, make estimates of its future output almost negligible.

The two main sands, the 800-foot, or shoestring sand, and the 900-foot, or Colony sand, will probably contribute most of the future production. The part of the county south of the Bush City field offers good prospects for more shoestring fields of the channel type. If these deposits are the fillings of stream channels, it does not appear reasonable to believe that more than one or two of the size of the Bush City field, and two or three narrower ones, are present, because streams 1/4 mile in width would be expected to be several miles apart. Minor branch deposits may be found, but as yet conclusive evidence of their existence has not been brought to light.

More small oil pools should be opened up in the Colony-Welda district between those already discovered, and also in the area one to two miles wide paralleling the west side of the trend now outlined. The best prospects are believed to be on the west side, because the sand was laid down as a near-shore deposit, with the sea lying to the west. It is easy to conceive how scattered sand bodies may have extended some distance off shore. The almost complete lack of sand east of the pools discovered to date makes it appear that the edge of the land bordered closely to the shoreline already traced out, and that east of that line channel fillings are the only type of deposits to be expected.

Northwest of Garnett and between Glenloch and Scipio many wildcat wells have found good showings of oil in 2 to 50 feet of sand at the 800-foot horizon. Enough oil was found in some wells that other tests were drilled only a location from those that had showings. Although no pools have been opened to date, the showings lend encouragement to the belief that this part of the county may yet yield commercial production.

It is doubtful whether any larger deposit of the Colony sand than that of the trend extending from Colony through Welda and northward will be found. The best place to expect this sand in large bodies is in the western third of the county, which has been tested by only a few wells. Many more small, narrow fields, such as have been developed near the eastern boundary of the county, will probably be opened up, some of them in general alignment with those found to date. Other north-south trends made up of similar small sand bodies may occur between this eastern series and. the large Colony-Welda sand body. Any gas in the 900-foot sand west of the Colony-Welda shoestring is more likely to have collected only under anticlines or domes, because the sand would be below the water-level as established by a line drawn between the water-bearing ends of this trend.

Considerable drilling has been done in the Harris-Westphalia-Northcott district, chiefly in search for oil or gas in the thick sand immediately above the Mississippian limestone. A very small gas pool near Northcott is the only favorable result of this drilling. A few showings of oil induce a few operators to prospect in this area. Because this sand holds water, tests should be drilled only on structures. The absence of key beds in most of the district prevents selection of the favorable areas. The fact that the sand is only partially filled with water in places must be taken into consideration in locating tests for oil which would most likely be found on the flanks of structures just above the water level. The gas, however, should occupy the highest points, regardless of the amount of water in the sand.

The weathered zone on top of the "Mississippi lime" in the southeastern part of the county locally is capable of producing small amounts of gas and heavy oil. The rapid depletion of the gas, that appears to be in "pockets," and the poor quality of the oil detract all commercial possibilities from this "sand" as long as the market for these products remains as it is.

The "first break" in the "lime" has furnished no production in this part of Kansas. It is worthy of being tested on structures by wells that have missed the upper sands.

The "second break" sand, represented by the top of the "siliceous lime," might furnish small pools of low-gravity oil. The accumulation of oil at this horizon is very sensitive to structural conditions. Oil in this "sand" in Montgomery and Chautauqua counties has collected in small pools at the top of domes with 20 to 40 feet of closure. The oil is heavy, 22 to 24 degrees Baume, and about the same grade would probably occur in Anderson County. In view of the difficulties of determining the structure below the Mississippian limestone, and the small pools of heavy oil to be expected, it does not appear that there is at present sufficient inducement for prospecting in this zone.

The fine, impure sand of the Anderson County fields probably gives up far less than the average percentage of oil obtained from sand by natural drainage. The large quantities left in the sand should act as an incentive for the application of artificial methods of recovery. These may be depended on to account for a large portion of the future supply. It is likely that air or gas pressure will be applied to most leases before they are abandoned. Mining methods may be adopted in the end.

Relation Between Accumulation and Structure in the Oil Shoestrings

The two main oil shoestring trends in the county show a marked relationship between the accumulation of the oil and gas, and structure. In the Bush City shoestring the largest oil wells, and those which had the most gas with the oil, were on the anticlinal portions of the trend; the smallest oil wells, and those which had very little gas, were in the synclines. An explanation for this exceptional accumulation in the waterless sand is based on the former greater saturation of the sand, higher rock pressure associated with a thicker overburden of sediments, and the character of the reservoir rock. Except for a few variations and additions, the writer is in accord with the theory offered by Rich (1926) to explain the present unsaturated condition of some of the shoestring sands. In the case of the Bush City shoestring it is believed the sand was originally filled with water, a portion of which was replaced by oil and gas. The customary gravitational separation in water-bearing sands took place—the oil and gas gathered in the higher parts of the trend and the water took up its position in the lower parts. It seems necessary to grant that the accumulation of gas and oil in the anticlinal portions of the trend took place while the sand held water—otherwise there would have been no inducement for them to segregate in these higher places. Equal volumes of oil and gas were not exchanged for water, because the sand is not saturated now, assuming, of course, that only negligible amounts of the hydrocarbons have escaped since they migrated into the sand. All the oil and gas available for this replacement may have been used before all the water was taken up. It is believed that the water continued to travel into nearby shales to replace that which escaped with gases formed during the metamorphism of the shale, or perhaps into nearby shales of continental origin that were never thoroughly saturated with water. [Note: More detailed discussion of unsaturated shales and their relationship to the "shoestring" oil sand is given under "Absence of Water from the Oil Sand," following] As the water-bearing portions of the trend became smaller, the gas slowly followed up the water as the latter withdrew. The spread of the gas was facilitated when the rock pressure was lowered by the erosion of the overlying sedimentary column. The gas carried some oil with it to the parts of the trend vacated last by the water—the synclines. However, the very fine-grained, silty sand retarded greatly the spread of the gas so that only small amounts of oil and gas reached the areas where the sand is down-folded. Although no data are available, it might be expected that the sand in the synclines contains more cement, left when the water was slowly reduced in volume and at last completely absorbed. This would also retard the movement of the oil and cause smaller wells.

A different condition may be noticed in the Garnett shoestring. The sand is filled with oil and gas throughout its course, there being no sections of light production as in the Bush City shoestring. It is believed that this is caused by a complete replacement of the former water in the sand with oil and gas. The higher parts of the shoestring are filled with gas; all the remainder with oil. (See Fig. 6.) Even the portion of the trend that crosses the deepest syncline in the county is thoroughly saturated with oil.

It is concluded that the relationship between accumulation and structure in the shoestrings depends on the degree of saturation of the sands with oil and gas, and the texture and purity of the sand. It is probable that the oil in an unsaturated coarse-grained sand would drain into the synclines.

Barren Sand and Sand Containing Heavy Oil

One of the greatest disappointments to oil operators who are drilling in shoestring territory, where sand deposits are so difficult to find, is the discovery of sand at the oil horizon that either shows no traces of gas, oil or water, or yields unmarketable oil. Examples of the former condition are the barren sections at the west ends of the Garnett and Bush City shoestrings; of the latter, scattered patches of sand in the eastern half of the county.

The oil becomes increasingly lower in gravity in the two shoestrings until the barren zone is reached. The more rapid decrease in the Bush City field may be due partly to leakage of the lighter constituents, because two higher, normally non oil-bearing sands hold a thick, asphaltic residue that is believed to have been deposited from oil and gas that escaped from the sand below. An unconfirmed report by early residents describes a gas seepage in the vicinity of the heavier-oil section.

The east edge of the barren zone in the Garnett shoestring is only a mile from a point where gas and oil were under pressure of 250 pounds per square inch. A similar condition existed in sec. 33, T. 20 S., R. 20 E., only half a mile from good gas wells in the same sand. One would naturally expect that the oil and gas would spread into the barren sand, the physical appearance of which differs but slightly from that which yields large quantities of oil. Rich (1926) has suggested that the barren ends of the shoestrings might be accounted for by the former presence of water that has since withdrawn to the westward. Water-bearing sand has been found at the shoestring horizon on the western edge of the county. The sand may be cemented so tightly by mineral matter or muddy sand between the barren and productive sections that the oil and gas cannot migrate. The barren sand is harder and lighter colored than the oil-bearing sand, being more nearly gray than brown. Some of each type of sand from the Garnett shoestring was tested with acid. A sample from the rich part of the shoestring in sec. 6, T. 21 S., R. 20 E., did not cause any effervescence. A sample from a well on the west side of sec. 3, which had oil of 29 degrees gravity, and another sample from a dry hole in sec. 5, T. 21 S., R. 19 E., which had 40 feet of "dry" sand, both showed some effervescence, thus suggesting a cement of calcium carbonate. Perhaps the character of the shale adjacent to the sand is responsible for the lack of oil and gas, particularly if accumulation is not dependent on distant migration. If the source of the hydrocarbons was in the underlying carbonaceous shales, a barren zone in the sand might reflect a "lean" condition in the shale. The relative richness of source-rocks of petroleum is controlled by kind, quality, and conditions for preservation of the organic material buried with them. These factors might change within short distances along a low shore line where the source material itself would exist in varying amounts. Some of the material might escape oxidation and ultimately be a source of oil and gas; some might not be favored with proper conditions and so might be destroyed. Perhaps the change from sand holding light oil through that containing increasingly heavier oil to the barren sand marks the westward change of the shales into which the channels cut-the change being from rich, carbonaceous lagoon shales to leaner marine shales. In some instances shales of continental origin that were never thoroughly saturated with water and held only a little oil may have acted as "blotters" to absorb the water from the sand without returning a noticeable contribution of oil.

Small patches of the 800-foot sand, that hold no oil or only small amounts of heavy oil, are found up the dip from the barren zones in the ends of the shoestrings. Some of these patches are very near the shoestring fields of 35- to 36-degree oil. The heavy oil can perhaps be explained best by the escape of a controlling percentage of the gas associated with the original oil of normal gravity. Assuming that the rate of natural leakage would be the same, and because there would be a relatively greater contact with avenues of escape through the surrounding shales, a small pool of oil would be depleted of a relatively larger portion of its lighter constituents than a large pool.

The pore spaces of the so-called barren sands are probably filled with small quantities of natural gas, and so would not be vacuums, as the word "barren" might imply [suggested to the writer by R. C. Moore].

Absence of Water from the Oil Sand

The absence of water from some of the shallow oil and gas sands of eastern Kansas and other parts of the Midcontinent field is a condition strange enough to attract more than passing notice. The lack of water reacts favorably to the operators in that the sand may be entirely penetrated when the wells are completed, and, when the casing is set properly, no trouble is experienced during operation by the invasion of water. A disadvantage may rest in the lack of pressure furnished by edge water in forcing the oil into the drill holes.

The term "dry" of the so-called dry sands has received different interpretations from geologists, some maintaining that the dryness is only apparent because the proportion of water to oil may be too small to be observed, or, in the case of sands that yield neither oil nor water, the interstices of the reservoir rock may be too fine to emit the contents. The latter condition is not related to this discussion which has to do with productive waterless oil sands.

There appears to be no room for doubt that the oil sand of Anderson County is free of water-at least to the extent that free water does not occur within the pore spaces. All the wells are drilled through the sand into the shale below, and none, even those in the synclines, produces water after several years of pumping. The color of the sand is not the light color generally associated with water sands.

It seems necessary to assume that the oil sands were water-bearing at one time, because, even though they were deposited under continental conditions and dried out, they would eventually be subjected to the entrance of water when later water-borne sediments were laid down over them. Therefore, the problem must be attacked with the idea of accounting for the subsequent elimination of the water, and with the supposition that the effective conditions were peculiar to particular stratigraphic horizons, because water-bearing oil and gas sands are both above and below the non-water-bearing oil sand near the top of the Cherokee shales.

The absence of water from sand has been attributed to:

  1. Hydration of minerals.
  2. Evaporation due to heat.
  3. Compaction.
  4. Cementation.
  5. Drainage as the result of elevation.
  6. Mode of origin.
  7. Absorption by unsaturated shales.
  8. Removal by gases.

Probably hydration would have little effect in the elimination of connate water in the sands, because there are few, if any, minerals in them that would take up water in chemical combination, and further, such a process would more likely have taken place when the sediments were being transported. The mica is clearly clastic material that was transported with the other constituents of the sand, and settled flat with the bedding.

Evaporation by heat due to increased depth would not be expected to take place, because corresponding increases in pressure would tend to prevent the water from reaching its boiling point.

Compaction might eliminate some water by "squeezing" during the early stages of the process, but the degree of saturation would treme of such a process would be reached when all the pore space were eliminated.

Although cementation might force out some of the water by filling up the pore space, the final effect would be the same as with compaction—the degree of saturation would remain the same. The extreme of such a process would be reached when all the pore space was taken up by the cement.

The situation might be pictured wherein partially saturated sand would become dry after their water content had drained down the dip. Difficulties arise in explaining this drainage from lenses of sand surrounded by shale and from a horizon between others that hold water.

Another theory suggests that the lack of water in the sands may be accounted for by the geologic conditions under which the sand and associated shale were laid down. The difference is thought to depend on whether the sediments, while being built up, were frequently exposed to the atmosphere because of their position near the shore or on flood plains, or were deposited in the sea and were never exposed to the atmosphere. Reeves (1917) accounts for the absence of water in some oil sands by the supposition that, because of their continental origin, the sands were not originally saturated with water. By experiments he found that water will not thoroughly penetrate 1/2 meter of fine-grained sand after it has stood under water for several weeks. However, it does not appear reasonable to the writer that the waterless oil sands in this district escaped original thorough saturation. No doubt the shoestring channels were filled with sand under water, and the other kinds of sand bodies at the oil horizon have the shape of those laid down in water.

The provision of unsaturated fine argillaceous sediments near the sand might give a working basis to account for the present lack of water in the sands. Perhaps muds deposited on low land near the sea during short periods of inundation would be dried and their pore spaces filled with air after the waters withdrew. The gray to white shale above the oil sand in this district has the appearance of air-dried material. King (1897-98), in discussing the entrance of rainwater into soil, states: "Where the surface is covered by this finer soil, even a moderate shower is likely to fill up the surface pores so completely as to prevent almost entirely the escape of the soil air, and this at the same time prevents the entrance of water. Under these conditions . . . the little moisture which finds entrance to the soil penetrates so short a distance under the great hindrance of estranged air that it is quickly returned to the surface by capillarity and lost by surface evaporation."

While it should not be expected that sheet water would be so effectively retarded from entrance into fine air-filled sediments, it seems possible that a thorough saturation would not result in all cases. When water spread over such sediments, probably some of the air would by-pass the water and bubble to the surface; other air might be driven back by the pressure of the water into the finest pore spaces and gradually be replaced by natural gas before the invading water reached it. After the addition of more sediments there would be no way of escape for the gas and it might eventually replace some of the water in the buried sands.

The original water content of some of the shale may have undergone partial depletion by being absorbed and carried away by gasses, principally methane, carbon dioxide, and nitrogen, which are formed during the metamorphism of organic matter (Mills and Wells, 1919). This process might be so effective under some circumstances that the shales would lose all their free water and be dry, except for the films of moisture lining the pore spaces. If this be true, the generally accepted view that the ground water occupies all the rocks within the zone of fracture must have exceptions additional to those best known, to include not only the waterless oil sands, but also the nonmarine shales that were never saturated with water and were dried by escaping gases. Furthermore, in areas where the strata lie nearly flat and where there is little inducement for underground circulation or ingress of surface water, the rocks may be characterized by alternating "dry" and "wet" zones, depending, according to their origin, on whether their original content of water has been retained.

The most plausible reasons for the absence of water from the oil sand, according to the view of the writer, provide: (1) shales sufficiently petroliferous to exchange oil and gas for all the water in the comparatively small bodies of sand imbedded in them, (2) unsaturated shales caused chiefly by the escape of water with gases formed during the metamorphism of the shale-the unsaturated condition would not be one of long duration but rather one which would bring about without delay the repletion of the water content of the shales by absorption of water from the coarser sands.

Discovering and Tracing Shoestring Sand Bodies

The evidence sought in the attempt to discover or trace shoestring sand bodies is divided into surface and subsurface indications. In Anderson County the search for surface evidence is confined to a study of structure, because all other kinds of evidence, such as seepages or bituminous deposits, are lacking. The surface structure has been employed theoretically on the basis of the following propositions:

  1. Sand bodies might be reflected by differential settling.
  2. Differential settling might reflect topographic features that favor the deposition of sand.
  3. The structure of the surface rocks might conform with the subsurface structure, the former representing a renewal of folding that took place before the sand was laid down. Further, that the synclinal areas might be above synclinal valleys that were occupied by streams now represented by channel fillings.

Some of the factors that would effect settling over sand bodies or their later detection are: (1) their thickness, (2) width in proportion to thickness, (3) purity, (4) weight of greatest overburden, (5) present distance from the surface, (6) influence of other agencies, such as uneven deposition or true folding, (7) type of conditions at the surface on which mapping is dependent, (8) personal equation represented in the geologist.

It should be easily understood how a thick sand body would be reflected more readily than a thin one. In the case of the former the settling differential between the sand and the surrounding shale would be large, and there would be a resultant large depression of the strata at the sides. However, a wide, thick sand body, that lensed out very gradually, might not cause dips that would attract attention. More settling should take place adjacent to a body of clean sand than one containing considerable material like that at the same horizon. As previously noted, the amount of compaction of shale has been shown to be related closely to the weight of the overburden (Hedberg, 1926). Additional data to take into account the factor of time would be of interest. Do Tertiary and Devonian (or older) shales compressed by equal weights of overburden have the same porosity? The "cavey" nature of Tertiary clays and sands in deep wells in the Gulf Coastal and California oil fields implies that the beds lack much of final compaction. If time is an important factor in the process of compaction, sand bodies in older formations would be more likely to cause reflective dips than those in younger formations. The depth to which erosion has removed the rocks is vital in disclosing surface evidence of a sand body. The ideal situation would be the removal of a great thickness of relatively old strata to within a short stratigraphic interval of the sand. Counteracting conditions, such as uneven deposition and true folding, may eliminate all effects of differential settling. Few areas are free of such influences, and, in the majority of cases, it is probable that upward reflection, if present, would not be represented by symmetrical dips that conform to the shape of the buried topographic feature, or depositional unit, but by irregular "wrinkles" or "noses,". the resultants of all opposing forces. Uneven deposition is compensated for rather peculiarly in many districts by relatively thicker sediments occurring over thin ones, so that the interval between the top and bottom of a thick series is nearly the same over a wide area, even though individual members are lenticular. The disadvantage of formations of uneven thickness lies principally in their unsuitability for mapping. In many instances the proper allowance cannot be made for depositional dips because no evidence of variations in thickness are noticeable unless both contacts of a formation are exposed, or sufficiently reliable well logs are available. As another limitation to the settling theory, the type of conditions at the surface on which mapping is dependent should be considered, Since it is desirable to examine the surface structure in great detail, the key beds should be well exposed, persistent, not too numerous and similar within a short stratigraphic distance, of uniform thickness, and preferably rather thin. Finally, the personal equation, the ability of the geologist to map the structure and interpret its origin, carries an influence.

The main issue concerned with differential settling over sand bodies does not involve its existence, which is readily granted, but its limitations. Ample proof has been found by the writer that settling has caused dips immediately above sand bodies in Anderson County. The position of the thin edges of some of the sand bodies, even the channel deposits, indicates that depression has taken place proportional to the thickness of the sand, and has given a slightly convex upper surface to a body that originally may have been more nearly flat. In one or two places, where the sand has exceptional thickness, it seems to have warped the surface rocks, but in the great majority of cases its effects appear to die out among the unexposed formations.

Closely allied with the differential settling theory in connection with sand bodies is that which postulates the reflection of topographic features favorable to the deposition of sand. These might include sea cliffs, headlands, or valleys. It is quite generally conceded that such features controlled the location of some of the Burgess sand that was laid down on the Mississippian floor in Kansas and Oklahoma. Since the Burgess sand carries very little oil and gas in Anderson County, it is not as earnestly sought as the other sands. No data are available to show whether the position of the sand is related in any way to the old Mississippian topography,

The most important sands were laid down during local breaks in the deposition of the thick Cherokee shales. The idea that compaction over the Mississippian topography would be pronounced enough to cause features that would control the location of sand deposits in the Cherokee muds does not seem tenable, because the mud floor should have been leveled off by wave action more rapidly than differential settling would create reflections. A further barrier to the use of this theory is the absence of key beds to decipher topography in these shales.

The examination of structure along the shoestring channel fillings has not revealed that they follow synclinal areas. Probably the streams flowed through wide shallow valleys independent of the dip of the rocks.

Subsurface evidence of certain kinds has been found to have more worth than surface evidence in the shallow fields of Anderson County. A suggested method by which the trend of sand bodies might be predicted involves contouring on a key bed a short distance above the sand, and which has been warped by differential settling. Swings in the contours would be expected to indicate swings in the trend of the sand. This method is impractical in this district because the limestones in the Marmaton formation (the ones closest to the main sands) consist of many thin beds that seldom receive proper recognition from the drillers, Since some of the errors in measurement are cumulative, and may amount to 10 to 20 feet in all, the data that might have the precise use suggested are untrustworthy. Furthermore, wells ahead of the trend would very likely have traces of the sand and these would carry more weight than structural data.

Traces of sand at the producing horizon, even sand that does not give showings of oil or gas, are important when areas are being outlined as possible- seats of sand deposition. A geologist should be present when wildcat wells are drilled in to note traces of sand that might not be enough to be shown in the log. The position of sand in depth might be so varied by topography or dip that it would not be at its usual depth and so be passed by without proper notice by operators who do not keep such effects in mind.

After the discovery of a new pool the geologist should learn as soon as possible the type of sand body that has been found. Suggestions are furnished by its regional location, but more accurately by its cross section. The most valuable information to use during development of a pool are isobathic contours of the sand. These not only indicate the thickness but outline the ground plan. By projecting the isobathic contours of the channel deposits, the thickness and position of the sand at undrilled locations can be foretold with surprising accuracy. Many dry holes on the edges of the trends can be avoided by paying attention to these sand-thickness maps.

Core drilling of the important sections of a well would give accurate samples that would allow uniform interpretations by a geologist. Features not disclosed by ordinary drill cuttings would undoubtedly be brought to light and lead to valuable conclusions. The opportunities to make such studies would be welcome.

General Conclusions

The following conclusions are offered by the writer from his observations of the shoestring oil and gas pools of Anderson County. [Note: The writer wishes to emphasize that these conclusions are based on studies of one particular area of eastern Kansas—one that represents the extreme in shoestring fields. Judgment cannot be passed on all of the shallow fields on the basis of this report, because in a large portion of the eastern part of the state the sands are sufficiently widespread to cause "structure" to be given the usual primary consideration.]

  1. Given a sand body filled with gas and water, the gas will collect in the highest part of the sand. Accumulation may be controlled by: (a) folding, (b) uneven deposition, (c) pinching out up the dip.
  2. Thin patches of sand or long, narrow channel deposits are not associated with any particular type of surface structure. The idea that the shoestring oil fields follow synclinal areas is not supported by facts. They occur under all types of flexures.
  3. Reflection of sand bodies in this district by differential settling does not appear to have been effective in the surface rocks. Strong evidence of such reflection in a few areas is so outbalanced by contrary evidence in many other areas that application of the settling theory cannot be made with the same degree of confidence as imposed in the structural theory in regions where conditions are favorable to it.
  4. The accumulation of oil and gas in the non-water-bearing sands is controlled by the elevation of the sand and its cleanness. Where there is an abundance of gas, the "highs" are occupied by it and the oil is forced to take up its position in the synclines. Where there is a small amount of gas, the oil is in greatest amounts in the "highs." The effect of structural conditions may be varied by the purity of the sand. [Note: This conclusion reflects a very exceptional condition that probably holds true only locally, where waterless oil sands are very fine-grained. The common condition wherein oil in waterless sands is pooled in synclines is represented in fields only a few miles farther south.]
  5. When exploring for new deposits or extensions of the oil sand, a geologist should grant more importance to indications of sand than to structure. Past experience has shown that it is dangerous to ignore a trace of sand at the significant horizon in preference to an untried structural theory.
  6. When exploring for gas, it is best to drill on structurally high places in line with the defined trend of a sand body. Local structure may be ignored if the position of the sand in respect to the regional dip is anticlinal. However, wells with larger volume may be looked for on the higher portions of a trend.
  7. Several noses along the thick body of 900-foot sand between Colony and Mont Ida should be kept in mind while more data are being collected to aid in the discovery of sand bodies. Perhaps future developments will point rather conclusively to the fact that noses, rather than closed structures, are the result of differential settling over sand bodies.
  8. Geologic methods must conform to the conditions in the territory in which they are applied. Many disappointments await the geologist who uses the practices with which he is most familiar in areas that lack the fundamental requisites on which those practices depend.

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Kansas Geological Survey, Geology
Placed on web Feb. 6, 2018; originally published June 15, 1927.
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