Search Documents

By Phillip B. Bucky, R. S. Taborelli

The term "longwall mining" is best known to coal men, although modifications of the method are continually being used in other fields. Longwall mining is of interest today because it makes for greater inechanization and better supervision at the working face, and therefore lower production costs and increased safety. It is an approach to the factory system of production, the high efficiency of which as compared to that in mines is well known. There is available an accumulation of experience regarding this work but coordination of experience is lacking and this series of experiments was undertaken to help serve this purpose. Model experiments were used for reasons of safety, cost and time, and because it has been previously shown1,2,3 that a scalar inodel built of the same material as the prototype will behave in a manner similar to that of the prototype, with time effects the same, if the effective weight of the model is increased in the same proportion as its linear dimenbions are decreased. This is accomplished by substituting a centrifugal for the gravitational field; i.e., placing the model in a centrifuge and controlling the strength of the centrifugal field by varying the rate of rotation. Many factors affect the behavior of the geologic material overlying a bed, therefore results and conclusions contained in this paper apply only to the conditions presented herein. Longwall Mining What Is Longwall Mining?—Agreement should be reached as to what constitutes longwall mining and therefore what constitutes a longwall face. Let longwall mining be defined as the mining procedure in which the roof and overlying bed breaks tend to parallel the working face. In the ordinary stope or room-and-pillar mining the roof breaks tend to

Jan 1, 1938

By Phillip B. Bucky, R. S. Taborelli

The term "longwall mining" is best known to coal men, although modifications of the method are continually being used in other fields. Longwall mining is of interest today because it makes for greater inechanization and better supervision at the working face, and therefore lower production costs and increased safety. It is an approach to the factory system of production, the high efficiency of which as compared to that in mines is well known. There is available an accumulation of experience regarding this work but coordination of experience is lacking and this series of experiments was undertaken to help serve this purpose. Model experiments were used for reasons of safety, cost and time, and because it has been previously shown1,2,3 that a scalar inodel built of the same material as the prototype will behave in a manner similar to that of the prototype, with time effects the same, if the effective weight of the model is increased in the same proportion as its linear dimenbions are decreased. This is accomplished by substituting a centrifugal for the gravitational field; i.e., placing the model in a centrifuge and controlling the strength of the centrifugal field by varying the rate of rotation. Many factors affect the behavior of the geologic material overlying a bed, therefore results and conclusions contained in this paper apply only to the conditions presented herein. Longwall Mining What Is Longwall Mining?—Agreement should be reached as to what constitutes longwall mining and therefore what constitutes a longwall face. Let longwall mining be defined as the mining procedure in which the roof and overlying bed breaks tend to parallel the working face. In the ordinary stope or room-and-pillar mining the roof breaks tend to

Jan 1, 1938

By Edwin R. Phelps, Charles W. Porterfield

BACKGROUND OF SURFACE MINING Surface mining refers to the process of removing the material (over- burden) overlying a coal seam and exposing the coal so that it can be loaded out and conveyed by trucks or other methods to the preparation plant or other facility. Surface mining has not always been important in the coal industry. In the early 1900s, almost all of the coal mined in the United States was mined by underground methods. In 1900, about 192 Mt (212 million st) of bituminous coal mere mined and less than 1% was mined by surface methods. The development and use of larger equipment has allowed surface mining to gain prominence throughout the years. Table 1 shows the total production of coal by mining method in the United States for ten-pear periods since 1920 and indicates the growth of surface-mined coal production. Surface mining will undoubtedly continue to account for a large percentage of the coal production in the US for many years because: 1) The capacity of surface mining excavators has continued to increase. Today, mining companies are using shovels (see Fig. 1) which are able to move up to 137.6 m3 (180 cu pd) in each bite and draglines (see Fig. 2) which move up to 168.2 m3 (220 cu pd) in each bucketful. 2) Increasing tonnage from the thick western coal seams is being produced by surface mining methods. 3) Surface mining has normally had lower costs and a better safety record than underground mining. 4) Surface mining normally recovers a much higher percentage of the coal reserve than can recovered by underground mining. 5) Some coal measures call best be extracted by surface mining

Jan 1, 1981

By R. W. Heins, N. Street

Recently Hiller1 reported results on the impairment of the strength of quartz glass rods through wetting, indicating that there was general agreement with the prediction of the Griffith formula in that for the liquids used the rods were weakest in water i.e. the liquid which probably had the greatest free energy of immersion. The Griffith equation predicts that the tensile stress necessary to propagate a crack of length c is where ? is the interfacial free energy, E Young's modulus. Since for a solid immersed in a liquid of surface tension ?L and contact angle 8 at the solid-liquid-gas contact, ?s - ?SL = ?L cos ? where ?s is the surface free energy of the solid. Hence comparison between ?L cos 0 and strength impairment should be possible. In a study of the usefulness of the Kuznetsov pendulum2 as a means of studying rock drillability we have determined the effects of various liquids on the pendulum hardness of Bavarian limestone. The pendulum used had diamond points (Burgess Vibro-graver), a period of 1.14 sec and a total on sample weight of 1191 g. The decline of the pendulum oscillations was recorded by a light beam on light sensitive paper carried on a kymograph. Rehbinder's expression relating hardness to amplitude attenuation as a function of time can be written In A = - (1/H) t + In Ao where A, A, = amplitude at time t and initial amplitude respectively, H = hardness parameter, and t = time. The line of best fit to the experimental points was determined using the IBM 7090 electronic computer, the computer also gave A, by extrapolation to zero time. The results for the various liquids tested are given in Table I and Fig. 1. The limestone surfaces were highly polished before testing and each reported hardness value represents the average of at least ten separate determinations of the pendulum decline curve. On each newly prepared surface the water value was again determined (also

Jan 1, 1964

By L. W. Legerwood

During the past three decades, the oil industry has expended increasing eflorts seeking improved drilling tools or systems to reduce drilling costs. The total cost of these efforts is unknown, but it certainly amounts 10 tens of millions of dollars. Most of the "new" system that past and present investigators have sought to develop actually are old public information. In seeking to implement new-systern concepts, investigators have tested the following: impact at frequencies ranging from 6 to 300 cycles per second; electrical, mechanical and hydraulic meam of actuating percussors; bit rotary speeds up to 2,000 rpm; electric and hydraulic bottom-hole means of rotating bits; bottom-hole machines with power outputs up to 400 hp; shock waves; explosives; high-velocity pellets; flame; arc; grinding wheels; abrasive jets; erosion by high-velocity gases; chemical attack; electric current; magnetic waves; retractable rock bits; reelable drill pipe; continuous coring with reverse circulation; and automation of drilling rigs. Table I shows how these investigations are grouped for discussion purposes in this paper. In spite of these efforts to discover new and improved systems, rotary drilling main;aim its economic leadership. Undoubtedly, rotary drilling costs will continue to be reduced by rigid application of the best available technology and by development of new rotary technology. In view of the extensive past development programs, however, significant long-range improvement appears to be a research, not a development problem. Research must postulate and prove theories and principles governing variour subsurface rock-failure processes pertinent to both rotary and new systems. Ah, research must produce physical and engineering data relative to these processes. When such information is available, earth boring will graduate from an art to a science. Major improvements in rotary drilling can then be expected, and the systematic evolution of an improved drilling method can be initiated—with a strong probability for success. Development of drilling methods other than rotary drilling has been one approach investigated by the industry as a means for reducing drilling costs. Major cost-reduction efforts, however, have been centered on engineering development work aimed at incremental improvements in rotary drilling. A relatively minor effort has been expended to establish basic physical principles and engineering data pertaining to the earth-boring process which can serve as a foundation for the development of cost-cutting drilling hardware. Current oil-industry economic trends have added impetus to the need for effective programs to reduce drilling costs. However, areas for expanded future efforts should be selected only after careful study of past investigations. It is the purpose of this paper to review past and Dresent industry efforts to develop new drilling tools or systems and to suggest areas where additional science is needed. Past reviews of drilling methods have been limited to a few processes prominent at the time the reviews were made. This paper seeks to present a concise, well organized review of all methods that have received actual development or test work. The preparation of a paper seeking to review all past developments is fraught with many difficulties, not the least of which are errors in or obsolesence of printed matter used as source material and the lack of data on industry developments which have not been published. Since de-

By E. A. Holbrook

LOCAL yearly taxes levied on bituminous coal lands in Pennsylvania have become a cost of first importance to the coal industry of the State. In Pennsylvania there is no State tax on real estate, but local taxation of real estate furnishes the greater part of the revenue necessary for the small governmental unit, as counties, townships, boroughs, and local school, road, and poor districts. Coal in place in the ground, whether or not title thereto has been severed from ownership of the surface, is assessed as real estate and on its supposed sale or market value. There are eight classes of counties in Pennsylvania, based on population; in populous counties of the first, second and third class, assessments are made by a county board appointed by the county commissioners and are fairly uniform throughout the county. In counties of the fourth to the eighth classes inclusive, property assessments are made by property assessors elected by and for each township within a county. In these counties the board of county commissioners acts as a board of equalization and review to hear appeals. In most counties, therefore, where there is a large unmined reserve of coal, assessments on that coal vary for each township, irrespective of the fact that the coal bed is continuous under many townships.

Jan 1, 1933

By Valentin R. Garfias, C. O. Isakson

The production of oil in Mexico during 1929 was approximately 45,000,000 bbl., or 5,000,000 bbl. less than in 1928. The production of the fields near Tampico showed a decline of over 10,000,000 bbl. for both the light and heavy crudes, which was partly offset by an increase of over 5,000,000 bbl. in the production of the fields in the Isthmus of Tehuantepec. During 1929 the retrenchment policy followed by practically all the companies was continued and no material improvement should be expected until the unsatisfactory conditions that brought about this situation are remedied. A new administration has just assumed control in Mexico; it should remain in power for 6 years, and the progress of the oil industry during that time will depend primarily on the policy pursued by the new government with respect to oil development. Development During 1929, there were drilled 214 wells as compared with 371 in 1928 and 583 in 1927. The percentage of producers in 1929 was 47.2 as against 34 per cent. in 1928. The new wells did not show water as quickly as in 1928, particularly in the Cacalilao field, where the greatest number of producers was brought in, their average initial daily production being 380 bbl. The flush daily production per well in the Southern fields was 1730 bbl., while the wells in the Isthmus of Tehuantepec came in with an average of 770 bbl. Development is summarized in Table 1. In the Southern fields 63 wells were drilled in 1929, of which 23 were producers, the best being drilled in Paso Real. This development tends to show that the southern extension of Dos Bocas-Alamo fault from Alamo to San Isidro terminates at San Isidro. The two wildcat wells completed in 1929, one in Magiscatzin and the other in Xicotencatl, were failures, and at the end of the year there were eight wildcat wells drilling and material was being hauled for two more.

Jan 1, 1930

By S. J. McCarroll

J. Bruce Clemmer, J. B. Rosenbaum, and C. H. Schack (U.S. Bureau of Mines, Salt Lake City)—We have watched with considerable interest Three Kids development of Manganese Inc. and have been impressed by the ingenuity with which management and staff have solved their many obstinate handling problems. Mr. McCarroll has been lenient in describing the difficulties faced by the company in developing a process for beneficiating Three Kids ore. The operation, equivalent in size to a 20,000-ton sulphide ore plant, is treating a unique ore by a flotation process pioneered by Manganese Inc. Perhaps the magnitude of the conditioning and flotation problems peculiar to Three Kids ore can be better appraised when it is pointed out that two-thirds to three-fourths of the ore is floated in the rougher step and that the four stages of cleaning which follow are equivalent to floating the whole plant feed two to three times. Our experience in both laboratory and pilot plant flotation of Three Kids and other manganese ores leads us to agree with Mr. McCarroll that suitable conditioning is a prime requisite for successful oil-emulsion flotation. The difficulties of proper conditioning were demonstrated in pilot plant processing of Artillery Peak manganese ore at our Boulder City, Nev., experiment station. Over three months of experiments and extensive plant revision were required before satisfactory conditioning was obtained in the 25-ton-per-day plant. Such factors as time, type and intensity of mixing, aeration, surface to volume relationship, and power input are still being studied by the Bureau of Mines in hopes of learning how best to condition manganese pulps for oil-emulsion flotation. Other factors affecting flotation of manganese with oil emulsion also deserve attention. A few of these are the influence of stability and proportion of ingredients in the collector emulsion, the feasibility of grinding

Jan 1, 1955

By C. C. Henning

In any line of human activity logical handling requires an amount of attention to each phase that is in keeping with the importance of that phase. In the complex and rapidly changing field of modern ferrous metallurgy it is difficult to allot the proper degree of attention to the various subjects, and it is not surprising that one or more subjects of major importance should for a time be neglected. Bessemer steel is a good example of a neglected subject. It is largely taken for granted, inferior physical quality is assumed for it, and there is a • lack of interest in its technical development and commercial application. Availability of supply is limited. In spite of this technical indifference, limited source and lack of commercial exploitation, bessemer steel constitutes a large volume of tonnage in daily use. There is a fairly prevalent idea even among technical people that bessemer steel survives mostly because of low cost and by reason of a dwindling residue of applications sufficiently common to permit of its use. The difference in cost between bessemer and open-hearth steel is governed largely by the relative cost of manufacture of pig iron and the market price of steel scrap. During the past four years there have been long periods of time during which the price of steel scrap was low enough so that open-hearth steel was considerably lower in manufacturing cost than bessemer. As to application, it may be pointed out that thousands of tons of this material in the form of bessemer screw steel are applied for moving parts in automotive and other equipment. Some forging work and considerable heat-treating, particularly carburizing, is performed on this grade. From an economic standpoint the most effective contribution of bessemer steel lies in its free machining qualities. It is by far the freest

Jan 1, 1935

By C. C. Henning

IN any line of human activity logical handling requires an amount of attention to each phase that is in keeping with the importance of that phase. In the complex and rapidly changing field of modern ferrous metallurgy it is difficult to allot the proper degree of attention to the various subjects, and it is not surprising that one or more subjects of major importance should for a time be neglected. Bessemer steel is a good example of a neglected subject. It is largely taken for granted, inferior physical quality is assumed for it, and there is a lack of interest in its technical development and commercial application. Availability of supply is limited. In spite of this technical indifference, limited source and lack of commercial exploitation, bessemer steel constitutes a large volume of tonnage in daily use. There is a fairly prevalent idea even among technical people that bessemer steel survives mostly because of low cost and by reason of a dwindling residue of applications sufficiently common to permit of its use. The difference in cost between bessemer and open-hearth steel is governed largely by the relative cost of manufacture of pig iron and the market price of steel scrap. During the past four years there have been long periods of time during which the price of steel scrap was low enough so that open-hearth steel was considerably lower in manufacturing cost than bessemer. As to application, it may be pointed out that thousands of tons of this material in the form of bessemer screw steel are applied for moving parts in automotive and other equipment, Some forging work and considerable heat treating, particularly carburizing, is performed on this grade. From an economic standpoint the most effective contribution of bessemer steel lies in its free machining qualities. It is by far the freest

Jan 1, 1935

By C. C. Henning

IN any line of human activity logical handling requires an amount of attention to each phase that is in keeping with the importance of that phase. In the complex and rapidly changing field of modern ferrous metallurgy it is difficult to allot the proper degree of attention to the various subjects, and it is not surprising that one or more subjects of major importance should for a time be neglected. Bessemer steel is a good example of a neglected subject. It is largely taken for granted, inferior physical quality is assumed for it, and there is a lack of interest in its technical development and commercial application. Availability of supply is limited. In spite of this technical indifference, limited source and lack of commercial exploitation, bessemer steel con-stitutes a large volume of tonnage in daily use. There is a fairly prev-alent idea even among technical people that bessemer steel survives mostly because of low cost and by reason of a dwindling residue of applica-tions sufficiently common to permit of its use. The difference in cost between bessemer and open-hearth steel is governed largely by the relative cost of manufacture of pig iron and the market price of steel scrap. During the past four years there have been long periods of time during which the price of steel scrap was low enough so that open-hearth steel was considerably lower in manufacturing cost than bessemer. As to application, it may be pointed out that thousands of tons of this material in the form of bessemer screw steel are applied for moving parts in automotive and other equipment. Some forging work and considerable heat treating, particularly carburizing, is performed on this grade.

Jan 1, 1935

By Harry M. Mikami

Chromite is the only ore mineral of metallic chromium and chromium compounds and chemicals. Because of this fact, chromite and chrome ore are used synonymously in trade literature. In commercial market quotations, chrome ore is the term commonly used. Chromite per se, because of properties imparted by its chromium content, is used in refractories and in special purpose moulding sands for metal casting. There are many other minerals containing some, generally minor, amounts of chromium, but none are commercial sources of the element (Thayer, 1956, p. 15). Chromium and chromite have many diverse uses that, directly and indirectly, critically affect vast segments of our modern industrial system. Most important are probably the metallurgical applications wherein chromium is a component of heat, abrasion, corrosion, and oxidation-resistant, and high strength alloys of many types. Stainless steels are the largest volume category of chrome-bearing alloys. Chromium chemicals are used in leather tanning, in pigments, dyes and mordants, printing, :hemica1 process industries, photography, pharmaceuticals, metal plating, pure chromium metal production, and for many other purposes. Chromite is a necessary constituent in basic refractories indispensable for the production of steel, copper, cement, and glass. Under present economic-political conditions, he U.S. and for that matter, North America, has virtually insignificant ore reserves of chromite. There are chromite deposits, as will be described, but they would only be used under highly abnormal conditions if all outside sources were cut off. All chromite used in the U.S. is imported from the eastern hemisphere in which are contained the principal world reserves. As the main suppliers in 1971-72 were the USSR, Turkey, Republic of South Africa, Philippines, and Rhodesia, the strategic nature of chromite is obvious.

Jan 1, 1975

By C. C. Henning

In any line of human activity logical handling requires an amount of attention to each phase that is in keeping with the importance of that phase. In the complex and rapidly changing field of modern ferrous metallurgy it is difficult to allot the proper degree of attention to the various subjects, and it is not surprising that one or more subjects of major importance should for a time be neglected. Bessemer steel is a good example of a neglected subject. It is largely taken for granted, inferior physical quality is assumed for it, and there is a • lack of interest in its technical development and commercial application. Availability of supply is limited. In spite of this technical indifference, limited source and lack of commercial exploitation, bessemer steel constitutes a large volume of tonnage in daily use. There is a fairly prevalent idea even among technical people that bessemer steel survives mostly because of low cost and by reason of a dwindling residue of applications sufficiently common to permit of its use. The difference in cost between bessemer and open-hearth steel is governed largely by the relative cost of manufacture of pig iron and the market price of steel scrap. During the past four years there have been long periods of time during which the price of steel scrap was low enough so that open-hearth steel was considerably lower in manufacturing cost than bessemer. As to application, it may be pointed out that thousands of tons of this material in the form of bessemer screw steel are applied for moving parts in automotive and other equipment. Some forging work and considerable heat-treating, particularly carburizing, is performed on this grade. From an economic standpoint the most effective contribution of bessemer steel lies in its free machining qualities. It is by far the freest

Jan 1, 1935

By E. C. Mahan

THE text of my talk was suggested by the invita-tion of your secretary, who said that the excess productive capacity of the bituminous industry was a matter of common concern to engineers and coal operators. Cognizant of the depressed condition of the industry, he tactfully added that in common council we might find wisdom. Certainly it would seem that the application of the best engineering knowledge available would be helpful in solving mining problems. There is no doubt that clear thinking, characteristic of the engineering type of mind, is essential to untangle the shapeless pattern which increased complication, so often mistaken for progress, has developed. There is much thinking today which neither looks forward to a logical combination of ideas nor backward to simple fundamentals. The result of that sort of thinking is hopeless confusion. Lately we have heard much about excess capacity and overproduction, along with their attendant evils. Respecting the bituminous coal industry, these terms have been frequently misused. How many of us have seen them applied to the coal industry but how few of us have understood them. I am reminded of a state-ment which William Green, president of the American Federation of Labor and a former miner from the Ohio field, gave to the Associated Press last month, in which he was quoted as saying: "The coal men must realize that conditions have altered since the World War. To-day they are producing a billion tons a year, with a market for only half that tonnage." I cite this instance as a glaring example of the flood of. loose statements about the bituminous industry with which the public is being deluged. If the general public, or some of the newspapers, had any passion for the facts, this sort of misleading statement would not get very far. Unfor-tunately, in these days, opinions are more sought after than facts, and statements by such a person as Mr. Green and are promptly accepted by a credulous public.

Jan 4, 1928

By Albert McIntosh

One of the most interesting as well as important factors connected with the petroleum industry is the consumption of motor fuel. A few years ago we always spoke of "gasoline," but when natural gasoline and benzol became more important it seemed desirable to include all of these products in the petroleum statistics and so there was adopted the term "motor fuel," which embraces these three products in their entirety. Gasoline always included all stove and motor gasolines, high-grade naphthas, cleaning naphthas, solvents, varnishmakers' and painters' naphtha and gas-machine gasoline. "Motor fuel" includes all of these products also; therefore, technically the term "motor fuel" is incorrect, but as the total quantity of these non-motor naphthas is small their inclusion does not distort the results to any appreciable extent. When the Federal Oil Conservation Board appointed its first semiannual forecasting committee early in 1930 to project the demand for gasoline and crude oil into the year 1930, it was necessary for that committee to formulate a method of forecasting. It adopted the system in use by some of the oil companies at that time, of using automobiles and per-car consumption. Six months later the American Petroleum Institute also formed a committee for forecasting, which adopted the committee principle of asking each member to produce his own forecast of demand by any method he thought best and to give a full explanation to the committee. The result of the latter method was to get the benefit of as many different methods of forecasting demand as there were members. The writer does not recall any two members ever using exactly the same method. By studying the different forecasts and their methods, there evolved a composite opinion, which was presented to the industry as the committee's estimate. The same method has been followed by the American Petroleum Institute or Planning and Coordination Committee ever since.

Jan 1, 1935

Discussion of the paper of IRVING A. PALMER, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 91, July, 1914, pp. 1447 to 1460. L. S. AUSTIN, Salt Lake City, Utah.-With the union of the Guggenheim interests and the American Smelting& Refining Co. in 1900, competition among the lead-smelting companies appeared to have been largely eliminated. This condition prevailed for but a short time, owing to the erection of smelteries by competing companies. Naturally, as competitors, the older companies endeavored to keep improved methods to themselves, not realizing, it would appear, that such knowledge could never be bottled up, but would drift into the common field of practice. Of late it has begun to be felt that more is gained than lost by adopting a franker and more open policy. The line, however, is drawn in. giving details of costs, which, fully known, it is felt, would be taken advantage of by a rival. As Mr. Palmer says, steady and substantial progress has been made, and latterly, I may add, the improvements have been radical. Sintering by the Huntington-Heberlein method or with Dwight-Lloyd machines has effected an important saving over reverberatory roasting, the cost being, say, 50 to 75c., as compared With $2 per ton by the older method. Moreover, the .large use of a sintered product has resulted in doubling blast-furnace tonnage. However, the change has not been an unmixed blessing, as in the machine roasting little time can be given to the breaking up of the blende, and it has been impossible to decompose largely the zinc sulphide, so detrimental in later blast-furnace treatment. The satisfactory roasting of the blende is still an unsolved problem. Nor is this all. For the best reduction it has been found that a part of-the change should be crude (unsintered) ore, indicating that the already fused material is only too ready to change to slag, thus lessening the opportunity for better reduction.

Jan 11, 1914

By H. J. Morel-Seytoux

Methods of predicting the influence of pattern geometry and mobility ratio on water flooding recovery predictions are discussed. Two methods of calculation are used separately or concurrently. The analytical method yields exact solutions in a convenient form for a unit mobility ratio piston-like displacement. A few typical pressure distributions, sweep efficiencies and oil recoveries are presented for various patterns. For non-unit mobility ratio, one may resort to a numerical method, such as that of Sheldon and Douherty. 1,2 Because the domains of applicability of the analytical and numerical techniques overlap, the exact solutions provide estimates of the errors in the numerical procedures. The advantages of the analytical and numerical methods can be combined. To develop a numerical technique as independent of geometry as possible, the physical space is transformed into a standard rectangle. The entire effect of geometry is rendered through one term, the "scale-factor", derived from mapping relations. The scale factor can be calcu-lated from the exact unit-mobility ratio solution for the particular pattern of interest. By this means recovery performances for arbitrary mobility ratio con be obtained for many patterns. A sample of tesults obtained in this manner is presented. INTRODUCTION Pattern geometry and mobility ratio are two major factors in making a waterflood recovery prediction. Because assisted recovery has become increasingly important to the oil industry, pattern configuration and mobility ratio also assume a greater significance in the assessment of the economic value of recovery projects. The influence of pattern geometry and mobility ratio in shaping a recovery curve and on the other quantities of interest to the reservoir engineer is the main subject of this paper. Much effort has already been spent on estimating quantitatively the influence of either pattern or mobility ratio or both on oil recovery. The literature reports many investigations of this nature. 3-9 However, many results or methods of recovery prediction presented in the literature cannot be considered fully satisfactory. Even for unit mobility ratio and piston-like displacement, where analytical solutions are available, the literature shows discrepancies. For non-unit mobility ratio, the divergence in the results is extreme. For infinite mobility ratio in a repeated five-spot, depending on the investigator, the sweep efficiency ranges from 0 per cent to 60 per cent. With respect to the influence of pattern on recovery, only the repeated five-spot has received much attention. Other confined patterns and pilot configurations have received very little attention. Two calculation methods are presented in this paper, either separately or concurrently: the analytical method of potential theory and the numerical method of finite-difference approximation. The analytical method is more restricted in scope than the finite-difference method, but it has the definite advantage of providing exact solutions within its range of applicability. If a unit-mobility ratio piston-like displacement is assumed, the analytical approach is possible. A few typical results are reported in this paper; the detailed description of the general method and of a great variety of results will be the subject of other articles. Fornon-unity mobility ratio, we must resort to a numerical scheme. The numerical technique is that which was described by Sheldon and Dougherty.l,2 It is not limited to piston-like displacement. However, mainly single interface results will be presented here. Because the respective domains of applicability of the analytical and the numerical method overlap, useful comparisons of exact and numerical solutions can be made for a variety of patterns. The advantages of the analytical and numerical approaches can be combined. The reason for the success of this analytical-numerical approach can be summarized in the following two points: 1. The numerical solution for arbitrary mobility ratio can be programmed most efficiently when the physical space in which the displacement actually takes place is transformed into a standard shape; and 2. This can be done with remarkable simplicity whenever an analytical expression for the pressure

Jan 1, 1966

By W. E. Wrather

The overproduction of crude oil in 1927 has received such widespread publicity, both within and without the industry, and the several factors which have brought about this situation are so thoroughly agreed upon by everyone, that it is unlikely the writer will in this brief review be able to contribute anything new. The entire story of low prices and demoralization revolves around two flush districts, Seminole and West Texas— the actual. performance of Seminole and the potential threat of West, Texas. The sustained production of California has been a contributing factor to this situation also. It seems reasonably certain that Seminole and West Texas will together dominate the industry during 1928, with Seminole probably destined to drop into second place, as additional pipe lines are completed into West Texas to care for its rapidly expanding production. It now appears inevitable that the production of 1928 will equal or exceed that of the past year, depending solely upon the rapidity wit,h which it is possible to market West Texas crude, and the degree of restraint which operators are willing to impose upon themselves in holding proved reserves of oil underground. Adversity has cultivated the growth of a promising spirit of cooperation which has accomplished practical results both at Seminole and in West Texas. Cooperation among oil producers has long been ardently hoped for, but prior to the past year it has never been effective on an important scale. The interests both of the industry and the public at large can best be conserved by cooperation in controlling production, and the widespread acceptance of this idea has paved the way for a more rational policy in the immediate future Production BY Major Districts The domestic production of the United States during 1927 amounted to 894,43.5,000 bbl. (Bureau of Mines), an increase over 1926 of approximately 128,000,000 bbl. California succeeded in maintaining its position of the past four years at 230,000,000 hbl. In 1923 with the Los Angeles

Jan 1, 1928

By E. P. Klier, Jane Jellison

The course of the transformations on cooling in a series of Cu-A1 alloys has been followed by means of thermal analysis, X-ray diffraction, and optical metallogrAphy. Specimen size was found to have a pronounced effect on the time of completion of the pearlite transformation due to modification in the unmber of nuclei. The ordeving transformation zvas observed for all cooling rates for all alloys studied, and is considered insuppvessible. At intermediate cooling' rates, a transitional struchire for 011 alloy compositions and based ox the bainite reaction was observed. The alloys of aluminum and copper possess a eu-tectoidal region at from about 9.4 to 16 pct Al. Above the critical temperature, the disordered bcc phase, 0, is stable. At subcritical temperatures, the 0 phase decomposes under equilibrium conditions into the stable phases, a and y,. At the eutectoid composition, these phases develop a lamellar pearlite structure, in appearance much like that found in steels. During rapid quenching from supercritical temperatures, the diffusion processes required for the formation of the equilibrium phases are suppressed, and the 0 transforms to an acicular martensitic phase, designated B or y' depending on the aluminum content, or to a mixture of the two. Early investigators of this system concentrated on determining the equilibrium phase diagram, ''' the structure of the equilibrium phases,3 and later the isothermal decomposition of the 0 phase at subcritical temperatures, or the decomposition of the martensite on tempering. Other work which treated the nonequilibrium transformations concentrated largely on the martensite transformations and the structure of the b and y' phases.15"17 Since the pearlite and martensite transformations in this system resemble those in steels, the one being formed by nucleation and growth of adjacent lamellae of the equilibrium phases, and the other by a diffusionless, shear-type transformation, the present study has been undertaken to investigate the structures formed on continuous cooling, with the objective of constructing cooling transformation diagrams analogous to those derived for alloy steel systems. In particular it was desired to determine whether parallels between the A1-Cu and iron-iron carbide systems on continuous cooling extended to encompass the intermediate phase, namely the bainite structures, which form by a combined martensitic-diffusion mechanism,'' but which are supersaturated with respect to the equilibrium phase upon which their crystal structure is based. To this end the transformations in representative alloys of the Cu-A1 B eutectoid system have been followed, using the methods of thermal analysis, X-ray diffraction, and optical microscopy. EXPERIMENTAL PROCEDURE Materials. The materials tested were those used by Klier and Grmko 5 in their study of the isothermal decomposition of these alloys. The alloys were melted in graphite crucibles and chill-cast into 5 by 2 by 1/4 in. ingots. The ingots were then hot-rolled to sheets 1/8, 1/16, and 1/32 in. thick. The compositions are given in Table I. Specimen Preparation. Specimens for thermal analysis were in the form of small squares approximately 1/4 in. on a side. For the 11.9 and 13.5 Al-Cu alloys, the sheet thickness was 1/16 in. and for the 10.5 A1-Cu alloy the 1/32-in. sheet was used. One lead of a chromel-alumel thermocouple was spot-welded to either face of the square with the specimen itself thus forming the hot junction of the thermocouple. Specimens for X-ray analysis were prepared as filings from martensitic sheet stock and were sealed in glass ampoules under 1/2 atm of argon. Metallographic examination of the powder specimens was carried out on a portion of the heat-treated filings mounted in lucite. All specimens were examined metallographic ally after etching

Jan 1, 1965

By Henry T. Mudd

FLUORSPAR is a nonmetallic mineral aggregate or mass containing a sufficient quantity of fluorite (CaF2) to be of commercial interest. It has only moderate value per unit of weight and its cost as a percentage of the cost of finished consumer products is nearly negligible. Nevertheless, it has wide and great industrial importance. In periods of national emergency it is a mineral without which many very necessary manufacturing processes would be greatly handicapped; a few could not exist. Fluorite contains 51.1 pct calcium and 48.9 pct fluorine. Industrial grades of fluorspar prepared for the consumer normally contain from 85 to 98 pct fluorite, depending on the use. The ores may contain as little as 30 pct fluorite, depending on many factors such as accessibility to transportation and markets, character of ore, and prices. Fluorite is a lustrous, glasslike mineral, generally translucent to transparent; it may be clear and colorless or range in color from slightly bluish through various shades of violet, amethyst, purple, green, and yellow. It crystallizes in the isometric system and possesses perfect octahedral cleavage. Commonly it occurs in masses of very pure crystal- line material with aggregates of cubical crystals in open spaces, but - it is also found in fine to coarse granular form. Banded veins and masses with fibrous, radiating structure occur locally. It is usually found associated more or less intimately with other minerals and rocks, from which it must be separated for commercial use. The specific gravity of fluorite is 3.18 and the hardness is 4 in the Mohs scale, compared with 7 for quartz and 3 for calcite. It is distinguished from calcite by its failure to effervesce with dilute hydrochloric acid. Heated with sulphuric acid, it gives off fumes of hydro- fluoric acid, which etch glass.22,25,33.34,35.41

Jan 1, 1949