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By B. G. Klugh

The present paper represents a preliminary investigation of the ultimate structure of iron-bearing materials which have been subjected to heat treatment for the purpose of agglomerating the fines, or for chemical changes, or for both. Primarily, the object of this inquiry was to determine the relation of the microstructure of each of these materials to its specific susceptibility to the action in the blast-furnace. It is hoped that this small contribution will serve as a nucleus to a line of research that will throw some light upon the debated questions involved in blast-roasting. Thus far the investigation has been conducted along lines of analogy of known principles, rather than through the application of any well-defined system of microscopic petrography. This is obviously due to the fact that we are dealing with ma-terials which are the artificial products of a new art, rather than with the natural materials from which the essence of the pure science has been evolved. In the limited time allowed for this research, it has been conducted upon those materials the chemical content of which allows of their use commercially in the blast-furnace. The following microphotographs are arranged in the order of the degree of complete fusion to which the mass in question has been subjected, in effectively binding the particles together. A very notable fact here clearly demonstrated is that the degree of fusion to which the material has been subjected is inversely proportional to the reducibility of the product. The characteristic of the material under consideration to which reducibility is almost universally attributed call be progressively traced in the following arrangement, through the identity of the obvious microscopic constituent. Furthermore, the degree of fusion to which a bod? has been subjected is recorded in the presence of resultant products of fusion in that body. Such readjustment is generally apparent

Jan 1, 1914

By I. Fatt

Relative permeability and relative electrical resistivity curves are obtained for networks of tubes with a tube radius distribution by means of a network of resistors used as an analog model. These curves are similar to those obtained from real porous media. The effects of pore size distribution and network structure on relative permeability and resistivity are demonstrated. INTRODUCTION Study of the dynamic properties of networks of single size tubes in paper IT' of this series has shown that the network model has flow properties similar to those observed on real porous media. The comparison of properties of single size tube networks with those of real porous media cannot be carried far because very few porous media have uniform size pores. The capillary pressure curve from most porous materials such as soil, sandstone, and sintered glass indicate that these materials have pore size distribution similar to those shown in Figs. 5-1, 9-1, and 10-I.† To properly test the network model, it is therefore necessary to compare the dynamic properties of real porous media with those of networks of tubes in which the tube radii are distributed accord- ing to the distributions in the aforementioned figures. A network in which the tube sizes are distributed cannot be treated in the same manner as a network of single size tubes. In the single size tube network, the relation between tube geometry, flow resistance, and tube volume did not have to be known if the assumption was made that whatever relation did exist was the same for all tubes in a particular network. In a network of distributed tube size, the relation between tube geometry and flow resistance must be known or assumed in order to replace the tubes by equivalent electrical resistors. Relation of Tube Geometry to Flow Resistance The interchangeability of tubes and electrical resistors in the network model is possible because of the analogy between Poiseuille's law and Ohm's law. Poiseuille's law for a cylinder is q= pr4/8µl ?P.........(1) where q is the volumetric rate of flow, µ is the viscosity, ?P is the pressure gradient, r is the tube radius, and 1 is the tube length. Ohm's law is I=1/R?E..........(2) where I is the flux and is equivalent to the volumetric rate in Poiseuille's law, R is the resistance, and ?E is the voltage gradient. Both laws give the flux as a function of the potential drop and the resistance of the medium. By analogy then, 1/R=pr4/8µl ?P...........(3)

Jan 1, 1957

By R. T. Torgerson, W. A. Baginski

Alloying studies were conducted on modifications of Cb-10W-1OHf (C-129) alloy as part of a cooperative alloy development effort between The Boeing Co. and the Wah Chang Corp. The purpose of these studies was to develop a fabricable, high- strength columbium alloy with superior melding properties. The initial investigations of alloy modifications were conducted using laboratory-melted button ingots. An alloy with the composition exhibited excellent veld ductility, elevated-ternpevature strength, and fabricability. The yttrium-modified alloy was desigrzated C-129Y and was selected for further developrnetzt. Three prodziction heats of C-129Y weve processed into sheet. Welding, forming, and tensile proper-lies are presented for this material. Tungsten-are welds of. C-129Y exhibited a minimum bend radius of 1/2T in the as-welded conditioti compared to 8T for C-129 alloy. An investigation was conducted on Disil coating of C-129Y and test data are presented on oxidation resistance and effects of re-entry environments. The excellent combination of strength, fabricability, weldability, and low transition temperature of C-129Y alloy offers potential design advantages for use of this alloy in structures of aerospace vehicles. It is atiticipated that C-129Y will rapidly supplant C-129 and similar alloys clue to the versatility provided by its impvoved welditzg properties. COLUMBIUM alloys with improved properties are required to achieve better performance and efficiency of radiation-cooled structures for re-entry vehicles and recoverable launch systems. Cooperative work by The Boeing Co. and the Wah Chang Corp. resulted in the development several years ago of C-129 alloy, a high-strength Cb-W-Hf alloy.' This alloy has received favorable consideration for many advanced designs of high-temperature structures due to its excellent combination of properties. However, this alloy exhibits low weld ductility unless given a high-temperature stress-relief treatment. For this reason the development effort was directed towards modification of the C-129 alloy composition (Cb-1OW-1OHf) to eliminate the need for post-weld heat treatment. This paper describes the successful development of an alloy meeting this requirement. This new alloy was designated C-129Y and has a nominal composition of EXPERIMENTAL PROCEDURES Alloying Studies. Various Cb-W-Hf compositions were investigated using are-melted button ingots. These buttons were hot-forged using a protective glass coating and rolled into sheet specimens. Metal-lographic examination: tensile testing, and welding studies were conducted to evaluate properties of the experimental alloys. Sheet Fabrication. Three pilot production heats of C-129Y were fabricated into sheet to establish processing techniques and to determine sheet properties. The three heats consisted of 6-in.-diam ingots weighing from 140 to 250 lb. The ingots were prepared by electron-be am melting followed by vacuum-arc melting. The hafnium and yttrium additions were made during the are-melting operation by tack welding alloy strip additions to the Cb-W master-alloy electrode. The final ingots were machined into billets with samples of the machine turnings collected for chemical analysis. Ingot breakdown methods for the three heats are as follows: Ingot Ingot Heat Size Weiaht___Breakdown Method A 6 in. 250 lb Hot extrusion B 6 in. 140 lb Hot forging C 6 in. 250 lb Hot extrusion Sheet bars from the extrusion and forging operations were conditioned, recrystallized, and rolled into sheet. Initial rolling was conducted at elevated temperatures and final rolling was conducted at room temperature.

Jan 1, 1967

By Richard L. Gordon

THE PROBLEMS AND POSSIBLE SOLUTIONS Toward the end of the 19th century, American industry began a drastic reorganization. The many, small, often-regional firms were supplanted by large national corporations-often produced by mergers among the existing firms. Giant companies appeared throughout American industry and many of them were engaged in the mineral industries.a The largest combines, by far, to emerge during the period were United States Steel and Standard Oil. Long before the restructuring had run its course, widespread concern arose over the process of concentration. Efforts were made to control, if not stop, the transformation. The concern produced the Sherman Antitrust Act of 1890 and the first of many federal regulatory agencies-the Interstate Commerce Commission (see Refs. 24, 31, 42). The basic objectives of these policies remain unclear to this day. The crucial issue is whether the goal is primarily to insure development of a more competitive economy or to preserve a social structure leaving more scope for small businesses. Complications arise from difficulties in agreeing upon the meaning of these terms. Studies of the early years of the antitrust movement suggest that it involved no particular concern over the mineral industries. Objections were directed at big companies in general. To be sure, the conservation movement arose in roughly the same period and did stress the evils of monopoly control of minerals. However, direct, continuing influence of conservation policy on antitrust is not apparent. Many of the most important antitrust cases, nevertheless, involved minerals. This, of course, may be sheer coincidence; the choice of cases has never followed any obvious pattern. Certainly, no simple hypothesis can explain the interest consistently. Once it may have been true that mineral industries were more likely than other sectors to be dominated by a few large companies. Yet, often sharp reversals of such tendencies -e.g., in oil and aluminum-have not removed antitrust interest. The importance of minerals to the economy cannot satisfactorily rationalize antitrust interest. The equally

Jan 1, 1976

By J. W. Snavely

THE high tension belt conveyor is introducing a new and tremendously expanded era of low cost bulk material handling. High tension belt conveyors are generally those installations involving very long centers, high lifts, or drops, in which the belts are stressed up to their maximum tension values, and further, where the belt construction provides tension capacity far beyond what is possible with conventional belt constructions. With these high tension installations, the magnitude of the forces involved demands careful refinement of accepted design practice in order to achieve optimum balance of all factors.

Jan 3, 1951

By W. N. Poundstone

The mining and ventilating system used in development work in the Pittsburgh Seam in northern West Virginia is discussed. The seam conditions and the nature of the accompanying methane gas are described. The type of equipment and the mining cycle will be discussed, showing how they are well suited for very gaseous development work. Face ventilation in development work is possibly the fastest growing problem of the industry. The coal mines of the future will be faced with the prospect of mining from under increasing depths of cover. Consequently, larger and larger amounts of methane gas probably will be found. The Pittsburgh Seam, in northern West Virginia, is an example of an area already faced with this problem. At the present time, most of the development work being done in this seam lies beneath 500 to 1200 ft of cover. The Pittsburgh Seam in this area has always been very gassy—even near the outcrop—and the recent development work has been accompanied with extremely large volumes of gas. In many cases, a single development section has liberated in excess of 1,000,000 cfm in 24 hr. This problem of heavy gas liberation was the chief concern, several years ago, when continuous mining equipment was first considered at Christopher Coal Co. All of us were apprehensive about the liberation that would accompany rapid extraction in a single working place. However, the experience during the past few years has shown that this ability to mine only one place at a time, is actually the key to working this type of coal. With all of the mining or advancement concentrated in one place, the ventilation can also be concentrated. By this it is meant that continuous mining permits the active working place to be ventilated with a maximum amount of fresh air, taken directly from the intake source without first passing another working place. Continuous mining (and a good ventilating system) also permits a much greater concentration of attention or vigilance to the actual working place. There are two things that are very important to the mining of coal having high rates of liberation. First, adequate volumes of air are necessary. Second, and perhaps more important, a mining and ventilating system must be used that will provide an uninterrupted flow of air to every portion of the working section. Liberations of this magnitude take only a few seconds of interruption for a dangerous accumulation of gas to occur. With adequate volumes of air available, the ability to concentrate ventilation more than offsets the concentration of gas emission that is inherent with continuous mining. The mining system used with continuous mining equipment at Humphrey Mine is similar to the system used at many mines in the area for development work. This system is designed to favor ventilation, realizing that other efficiencies are meaningless if the equipment must stop because of ventilation difficulties. This plan is especially well suited to minimizing ventilation interruptions. Basically, the overall plan of mining is to develop headings into virgin coal and encircle or block out large areas. These blocks are generally at least 2000 ft sq. The purpose of this blocking out is to bleed gas from the area before pillaring. Experience has shown this method to be quite effective, even in the most gassy areas. The gas in this field seems to migrate or flow readily from the solid coal into the outside return headings of the development work. The numerous clay veins and slips that are found in the area are extremely good avenues for gas flow. A block of coal, surrounded with development headings, usually bleeds off readily; and since it is cut off from the virgin coal, it is not subject to gas migration, through the seam, from this source. However, the outside return of the encircling development work, adjacent to the virgin coal, may liberate gas for years. This liberation from the outside ribs in the virgin coal is the reason split ventilation is used in development work. If split ventilation were not used, there would, in many cases, be a serious build-up of gas in the intake before it could reach the working face. Fig. 1 shows a typical development section having seven headings. The two outside places on each side are returns, and the three center headings serve as intakes. This section is equipped with a ripper-type continuous mining machine. An off-track loading machine is used to load from a surge pile on the

Jan 1, 1961

Occasionally it is interesting, and sometimes useful, to review the past for early references to our industry, and to learn of the trials and travail passed through before it arrived where it now is - and the results of such a review follow. Some time ago one of our modern playwrights and poets, Arthur Guiterman, turned to coal, with the following result : Afar in the Carboniferous time I grew in Paleozoical slime, A lepidodendron with boughs on my stem And lepidostrobusea grew out of them. My roots in the mud of the ages I spread And up to the heavens I vaunted my head, I throve in the heat of tropical sun, And now I am coal at two dollars a ton.

Jan 1, 1935

By Walter Rose, W. A. Bruce

Improved apparatus, methods, and experimental techniques for determining the capillary pressure-saturation relation are described in detail. In this connection a new multi-core procedure has been developed which simplifies the experimental work in the study of relatively homogeneous reservoirs. The basic theory concerning the Leverett capillary pressure function has been extended and has been given some practical application. Some discussion is presented to indicate the relationship of relative permeability to capillary pressure, and to provide a new description of capillary pressure phenomena by introducing the concept of the psi function. INTRODUCTION For the purposes of this paper the capillary character of a porous medium will be defined to express the basic properties of the system, which produce observed results of fluid behavior. These basic properties may be classified in the following manner, according to their relationship to: (a) The geometrical configuration of the interstitial spaces. This involves consideration of the packing of the particles, producing points of grain contact, and variations in pore size distribution. The packing itself is often modified by the secondary processes of mineralization which introduces factors of cementation, and of solution action which causes alteration of pore structure. (b) The physical and chemical nature of the interstitial surfaces. This involves consideration of the presence of interstitial clay coatings, the existence of non-uniform wetting surfaces; or, more generally, a consideration of the tendency towards variable interaction between the interstitial surfaces and the fluid phases saturating the interstitial spaces. (c) The physical and chemical properties of the fluid phases in contact with the interstitial surfaces. This involves consideration of the factors of surface, interfacial and adhesion tensions; contact angles; viscosity; density difference between immiscible fluid phases; and other fluid properties. Fine grained, granular, porous materials such as found in petroleum reser~oir rock possess characteristics which are expressible by (1) permeability, (2) porosity, and (3) the capillary pressure-saturation behavior of immiscible fluids in this medium. These three measurable macroscopic properties depend upon the microscopic properties enumerated above in a manner which defines the capillary character. Systems of capillary tubes or regularly packed spheres may be thought of as ideal and numerous references can be cited in which exact mathematical formulations are developed to show the relationships governing the static distribution and dynamic motion of fluids in their interstitial spaces. The capillary character of non-ideal porous systems such as reservoir rock also is basic in determining the behavior of fluids contained therein; although, in general, the connection is not mathematically derivable but must be approached through indirect experimental measurement. This paper gives consideration to the evaluation of petroleum reservoir rock capillary character. The methods employed may be applied to the solution of problems in other fields, and the conclusions reached should contribute to the basic capillary theory of any porous system containing fluid phases. In this paper, a modification of the core analysis method of capillary pressure is employed and it is intended to show that the capillary character of reservoir rock can be expressed in terms of experimental quantities. A very general method of interpretation correlating the capillary pressure tests with fundamental characteristics such as rock texture, surface areas, permeability, occasionally clay content and cementation is introduced. Eventually an attempt is made for establishing a method of deriving relative permeability to the wetting phase from capillary pressure data. The experimental evaluation of capillary character must be approached in a statistical manner if reservoir properties are to be inferred from data on small cores. This is implied by the heterogeneous character of most petroleum reservoirs, and suggests that considerable intelligence should be applied in core sampling. Finally, this paper supports the view that once the capillary character of a given type of reservoir rock has been established by core analysis, fluid behavior can then be inferred in other similar rock. Although no great progress has been made in establishing what variation can be tolerated without altering the basic fluid behavior properties, evidence will be presented to indicate that certain reservoir formations are sufficiently homogenous with respect to capillary character that the data obtained on one core will be useful in predicting the properties of other cores of similar origin. Tests have shown that cores under consideration can vary widely with respect to porosity and permeability and still be considered similar in capillary character. EXPERIMENTAL METHODS AND TECHNIQUES Various types of displacement cell apparatus for capillary pressure experiments have been described in the literature. Bruce and Welge; Thornton and Marshall; McCullough, Albaugh and Jones3; Hassler and Brunner; Lever-

Jan 1, 1949

By Walter Rose, W. A. Bruce

Improved apparatus, methods, and experimental techniques for determining the capillary pressure-saturation relation are described in detail. In this connection a new multi-core procedure has been developed which simplifies the experimental work in the study of relatively homogeneous reservoirs. The basic theory concerning the Leverett capillary pressure function has been extended and has been given some practical application. Some discussion is presented to indicate the relationship of relative permeability to capillary pressure, and to provide a new description of capillary pressure phenomena by introducing the concept of the psi function. INTRODUCTION For the purposes of this paper the capillary character of a porous medium will be defined to express the basic properties of the system, which produce observed results of fluid behavior. These basic properties may be classified in the following manner, according to their relationship to: (a) The geometrical configuration of the interstitial spaces. This involves consideration of the packing of the particles, producing points of grain contact, and variations in pore size distribution. The packing itself is often modified by the secondary processes of mineralization which introduces factors of cementation, and of solution action which causes alteration of pore structure. (b) The physical and chemical nature of the interstitial surfaces. This involves consideration of the presence of interstitial clay coatings, the existence of non-uniform wetting surfaces; or, more generally, a consideration of the tendency towards variable interaction between the interstitial surfaces and the fluid phases saturating the interstitial spaces. (c) The physical and chemical properties of the fluid phases in contact with the interstitial surfaces. This involves consideration of the factors of surface, interfacial and adhesion tensions; contact angles; viscosity; density difference between immiscible fluid phases; and other fluid properties. Fine grained, granular, porous materials such as found in petroleum reser~oir rock possess characteristics which are expressible by (1) permeability, (2) porosity, and (3) the capillary pressure-saturation behavior of immiscible fluids in this medium. These three measurable macroscopic properties depend upon the microscopic properties enumerated above in a manner which defines the capillary character. Systems of capillary tubes or regularly packed spheres may be thought of as ideal and numerous references can be cited in which exact mathematical formulations are developed to show the relationships governing the static distribution and dynamic motion of fluids in their interstitial spaces. The capillary character of non-ideal porous systems such as reservoir rock also is basic in determining the behavior of fluids contained therein; although, in general, the connection is not mathematically derivable but must be approached through indirect experimental measurement. This paper gives consideration to the evaluation of petroleum reservoir rock capillary character. The methods employed may be applied to the solution of problems in other fields, and the conclusions reached should contribute to the basic capillary theory of any porous system containing fluid phases. In this paper, a modification of the core analysis method of capillary pressure is employed and it is intended to show that the capillary character of reservoir rock can be expressed in terms of experimental quantities. A very general method of interpretation correlating the capillary pressure tests with fundamental characteristics such as rock texture, surface areas, permeability, occasionally clay content and cementation is introduced. Eventually an attempt is made for establishing a method of deriving relative permeability to the wetting phase from capillary pressure data. The experimental evaluation of capillary character must be approached in a statistical manner if reservoir properties are to be inferred from data on small cores. This is implied by the heterogeneous character of most petroleum reservoirs, and suggests that considerable intelligence should be applied in core sampling. Finally, this paper supports the view that once the capillary character of a given type of reservoir rock has been established by core analysis, fluid behavior can then be inferred in other similar rock. Although no great progress has been made in establishing what variation can be tolerated without altering the basic fluid behavior properties, evidence will be presented to indicate that certain reservoir formations are sufficiently homogenous with respect to capillary character that the data obtained on one core will be useful in predicting the properties of other cores of similar origin. Tests have shown that cores under consideration can vary widely with respect to porosity and permeability and still be considered similar in capillary character. EXPERIMENTAL METHODS AND TECHNIQUES Various types of displacement cell apparatus for capillary pressure experiments have been described in the literature. Bruce and Welge; Thornton and Marshall; McCullough, Albaugh and Jones3; Hassler and Brunner; Lever-

Jan 1, 1949

By H. Kazemi

A pressure fall-off test on the injection well of a forward combustion project may permit us to calculate the distance to the burning front. In the mathematical description and analysis of test data, we have considered the effect of temperature on the thermodynamic properties of reservoir fluids. The temperature distribution predicted by Chu' for a combustion wave has been used in analyzing a field test. Numerical solutions were obtained by simultaneous solution of the flow equation, the continuity quation and the equation of state. Although this analysis conccntrated on isotropic systems, the results can be extended to systems having directional permeability. INTRODUCTION Conventional pressure fall-off tests have been used extensively to determine reservoir characteristics in gas- or water-injection projects.- such tests consist of injecting fluid into the formation at a constant rate until steady state is nearly achieved, then discontinuing injection and measuring the bottom-hole pressure as a function of time. A plot of pressure vs the logarithm of time (measured from the instant of shut-in) yields a smooth curve characterized by three distinct regions (Fig. 1): Region I reflects the permeability alterations in the vicinity of the wellbore; Region II reflects the reservoir characteristics further away from the wellbore; and Region 111, the characteristics in the displaced fluid bank. The curves in Regions II and III are straight lines! the slopes of which are proportional to the reciprocal of the flow capacity of the formation behind and ahead of the interface as shown by Eq. 1, respectively:

Jan 1, 1967

By T. M. Broderick

INVESTIGATIONS into the possibilities of economically mining and concentrating low-grade iron ores of the Lake Superior region are attract-ing increasing attention. Among the organizations that are carrying on the work are the United States Bureau of Mines, the State of Minne-sota (which spends about $80,000 annually on problems of the 'iron and ferroalloy ores of Minnesota), and the State of Michigan (which spends about $10,000 annually of its iron-ore research). Several of the mining companies are also financing research. Of the states in the Lake Superior district, Minnesota has done most in iron-ore concentration. In 1930, thirty-seven concentrating plants were in operation on the Mesabi Range, beneficiating about one-third of the total ore shipped. About one-half of these plants reduced silica; the others reduced moisture or improved the structure of the ore.1 Research into the possibilities of magnetic concentration of the Eastern Mesabi magnetite ores indicates that vast tonnages of that ore may be utilized at a profit in the not distant future. Magnetic concentration has also been tried at Sellwood, Ontario, on the Moose Mountain deposit, and at the Berkshire mine in Wisconsin on the magnetic ores of the Western Gogebic Range. There have been few attempts to concentrate Michigan iron ores. In order to determine the possibilities of such concentration, iron-ore research has been carried on at the Michigan College of Mining and Technology for the past few years. After a general survey of the iron ores of the state, a program of more detailed experimentation was out-lined, starting with work on the Ironwood formation of the Gogebic Range. The results of this research led to the belief that gravity methods will produce fairly satisfactory concentrates from the parts of the iron formation that are made up of comparatively thick alternating beds of rather high-grade ore and lean chert.

Jan 1, 1933

By H. J. French

Within the past few years, particularly because of the rapid growth of the airplane industry during the war, considerable attention has been paid to the manufacture of light-wall cold-drawn seamless and welded steel tubing for structural purposes. While the manufacture of such tubing is not, in itself, a difficult matter, some difficulties have been encountered in producing the same under specifications requiring definite physical properties. It is the purpose of this paper to describe the methods of manufacture and the properties that may be obtained by such methods for tubing coming within about 1/2 to 2 in. (12.7 to 50.8 mm.) outside diameter and 10 to 22 Birmingham wire gage (0.134 to 0.028 in. wall thickness). Such tubing is largely used as structural material in the aircraft industry, and it is of the utmost importance that the physical and chemical properties should be known, and also that the various factors entering into the manufacture should be under such control as to allow these properties to be varied and held within definite limits. In general, tubing may be divided into four classes: namely, specialty tubing, such as riveted-sheet or plate, lock jointed, etc.; brazed tubing; welded tubing; and seamless tubing. Welded tubing may be divided into hot product, such as lap welded and butt welded, and cold product, such as acetylene and electric welded. Seamless tubing may be hot rolled or cold drawn. Specialty Tubing The first two classes present mainly mechanical or structural engineering problems. A simple form of tube is made by riveting together the overlapping edges of rolled sheets or plates formed into a cylinder. Because of the nature of its construction, such a tube is necessarily limited to relatively large sizes. Lock-jointed tubing is produced by passing low-carbon strip through a forming machine having suitable rolls and dies, its manufacture is almost entirely a question of design of the forming machine and its satisfactory operation. The chief application of such tubing is in the manufacture of bedsteads.

Jan 1, 1920

By K. K. Clark

Excessive injection pressures in water injection wells may create deeply penetrating fractures, or may open up existing reservoir fractures. If these fractures are oriented toward offset producing wells, oil recovery at injected water breakthrough and ultimate recovery will be impaired. A method of calculating fracture lengths from pressure fall-off test data is presented. The method is based on a linear flow model that simulates conditions present during the early-time period after shutting in an injection well. Fracture lengths can be calculated directly if formation permeability is known. A graphical technique is presented that provides fracture lengths based on permeabilities calculated from normal fall-off tests, where those permeabilities are adjusted for flow geometry. Test data from four injection wells and results obtained from applying the method to these wells are discussed. Introduction Rates of water injection into nonstimulated wells in low permeability reservoirs frequently fall below economically desirable levels. Therefore, some form of stimulation such as hydraulic fracturing often is performed on these wells. Usually these fractures penetrate a short distance from the well — short as compared with interwell spacing — and therefore should not create problems of water channeling to offset producing wells. In the past, some operators have been tempted to increase injection pressures continually to maintain a specified injection rate. But pressures cannot be increased indefinitely. Field data indicate that continued injection above fracture opening pressure can cause excessively long fractures to approach between well distances. If these long fractures intersect or closely approach offset producing wells, premature water breakthrough can result. It is difficult to seal effectively these fractures by various workover procedures after premature water breakthrough has occurred. This paper describes testing procedures that are potentially capable of detecting premature water breakthrough before it occurs. Knowledge of fracture lengths and fracture opening pressures can assist field engineers in selecting optimum operating conditions for water injection wells. Fracture lengths should be calculated from pressure fall-off tests on injection wells, and maximum permissible iniection pressures should be determined from step-rate injectivity tests. Equipped with this information, the field engineer is in a better position to recommend for a particular injection well the optimum operating conditions that will lessen the chances of channeling to offset producers. Historically, pressure transient tests have been conducted primarily on producing wells and analysis procedures have been based on radial flow concepts. Several authors have suggested that these same procedures be applied to tests conducted on water injection wells. This application is justified for wells that are not connected to extensive fracture systems. However, if the formation is severely fractured, the interpretation methods must be modified. Several authors have presented the pressure response of various systems that are intended to simulate reservoir conditions. A paper by Russell and Truitt* on vertically fractured svstems is probablv the most useful from the standpoint bf the fieid engineer. Russell and Truitt presented the pressure-vs-time behavior of a well connected to vertical fractures with various fixed lengths. Their permeability adjustment technique is used in this paper to refine methods of calculating fracture length and interwell permeability. Theory and Definitions Three flow-system geometries are considered in analyzing injection well test data. These various geometries are applicable during specific time intervals of transient pressure tests. Schematic drawings of the flow models, and the time intervals over which they are applicable, are shown in Fig. 1 in the chronological order that they are applied to the pressure response of water injection wells in fractured formations. The very early response is simulated by an infinite linear system as shown in Fig. 1A. This representation permits the calculation of matrix surface area exposed to the fracture. The model shown in Fig. 1B is identical with the one studied by Russell and Truitt. They evaluated the transient pressure response of this vertically fractured system by finite difference techniques. The results were presented as tabulations of dimensionless pressure drop functions for a range of fracture lengths. A semilog plot of these data shows that the apparent matrix permeability can be related to the true matrix permeability by a simple exponential function. Their adjustment factor is used in this paper to improve the accuracy of matrix-permeability and fracture-length calculations.

Jan 1, 1969

By R. A. Cunningham, A. S. Murray

If a dense fluid such as mud or water is used for circulation, the formation drilled is influenced by a hydrostatic pressure. This pressure depends on hole depth arid drilling fluid density. Laboratory tests indicute that drilling rates in many forri~ations are decreased with increased pressure,—in some cases as much as 90 per cent. A comparison between laboratory and field tests indicates that drilling fluid head affects drilling rates in the field approximately the, same as in the laboratory. Drillirrg rates of many formations are increased by reducing drilling fluid head. INTRODUCTION For many years it has been noted that field and laboratory drilling rate tests did not agree even when the formations tested were the same. For instance, tests of some shales by the Hughes Tool Co. laboratory indicated drilling rates approximately 20 to 30 ft/hour, whereas in the ground this shale would drill only 3 to 5 ft/hour. A possible reason for this discrepancy is the effect of the high pressure which the drilling fluid exerts against the formation at the bottom of the hole. Consider a small element of rock (Fig. II that is to be removed by a rock bit. If the hole is filled with mud or water. the upper surface of the rock element is subjected to a pressure which depends on hole depth and fluid density. The mass of earth around this rock element presses against the circumferential surface and the lower surface. Because of the probability of shearing stresses between the rock element and the surrounding rock, this element is not under true hydrostatic stress. However, as a first approximation for test purposes the rock element was assumed to he under hydrostatic stress. The effect of hydrostatic pressure on some physical properties of rock has been studied.1,2,3 These tests show that the "differential" compres-sive stress:': necessary to cause rup- ture in rock cylinders is greater when tested under high hydrostatic pressure than when tested under atmospheric conditions. These tests were made with pressures greater than 20,000 psi which is in excess of those normally encountered in oil well drilling. Similar tests were made by the Bureau of Reclamation' using pressures equivalent to those encountered in oil well drilling. Again the "differential" compressive stress necessary to produce failure increased with increasing hydrostatic pressure. These tests indicated that drilling rates would probably decrease. Correlation between these tests and drilling tests was not practical. The purpose of this work is to study the effect of mud column pressure on drilling rate, assuming that the material drilled is in a state of hydrostatic strcss. This problem was initially investigated in the laboratory using variable bit loads and confining pressure;. Confirmation of laboratory results was obtained in the field from a series of carefully controlled drilling tests. Because of the necessity of testing many different types of formations. only results from representative formations will be presented here.

Jan 1, 1956

By H. M. Chance

(Butte Meeting, August, 1913.) ADEQUATE treatment of the difficulties surrounding the valuation of mineral lands requires that agreement be first reached defining value as understood for the purpose of appraisal. To define value as the price of a product is not sufficient, and does not assist us in using the factors that cause variations in values and in relative values. The real value of any product depends primarily upon its relation to the necessities, comforts and pleasures of mankind. As the necessities, comforts and pleasures of the civilized races differ from those of more primitive man, the value of products varies with the degree of civilization and the environment of the consumer. Coal has no value to the savages of warm climates, and arrow-head flint none to the residents of New York. It has long been recognized that what has been termed ? intrinsic value " must be limited to materials that are essential to existence-air, water, food. But "intrinsic value" cannot be measured in monetary terms. The intrinsic value of a bushel of wheat is due to the fact that it will support the life of an individual for a certain definite time, but this fact does not enable us to measure or to express that value in monetary terms. It has often been proposed to adopt as a measure of the value of any product the quantity of labor necessary to produce it, but this method is of limited application, and will not apply to what may be termed "intrinsic values." For many reasons it might be well, while assenting to the fact that any material may he intrinsically valuable, to abandon the use of the term " intrinsic value." One of these reasons is the tendency to confuse the idea of intrinsic value with a value that is conferred by economic conditions, that is purely artificial and that may be permanent or evanescent; Intrinsic value must from its nature be permanent and unchangeable.

Jan 7, 1913

By L. D. Fetterolf

The New Jersey Zinc Zompany operates at Depue, Illinois, an integrated zinc smelting plant using tie vertical retort reduction process. The overall operation comprises green concentrate roasting, sintering, vertical retort smelting and metal refining. In the roasting operation, the fine concentrate is pelletized, the dried pellets fluidized and autogenously roasted with air in a “fluid column” with minimal formation of dust requiring recirculation. The roasted pellets and any associated roaster dust are agglomerated in a rotating drum and laid down, in combination with coal for fuel, on a Dwight-Lloyd sintering machine which converts to a semi-fused mass - a physical state more suitable for vertical retort smelting. The smeltins plant of 27 vertical retorts rated at 8 T zinc each per day on average requires the following major processing steps - mix preparation and briquettine, briquet coking, vertical retort reduction, vapor condensation and slab casting of metal. A portion of zinc production is converted to 99.99+ percent purity by boiling and fractional distillation in columns consisting of externally heated, superimposed trays of high-conductivity refractory.

Jan 1, 1970

By P. W. George

This paper presents geological data regarding deposits of over 7,500,000 tons of fine-grained sulphide ore in barite gangue. A series of pyroclastics and arkoses was intruded by sills of quartz porphyry in connection with batholithic intrusions of granite 3 miles from Buchans. Gentle folding, with fracturing and shearing of tuff beds and intruded quartz porphyry, accompanied and followed the intrusion of granite and porphyry. The sulphide-barite mineralization is localized primarily in fractured and sheared tuff beds, but also in the sheared quartz porphyry. Two structures have proved particularly favorable for mineralization-one, the center of an anticline; the other, a series of weak, incompetent tuff beds intruded by thin sills of quartz porphyry and located between strong beds of arkose. During the folding the weak tuff with intruded quartz porphyry was intensely sheared and contorted and subsequently mineralized by sulphides and barite. INTRODUCTION Buchans is 5 miles north of Red Indian Lake, in Central Newfound- land, at an elevation of 900 ft. above sea level and 400 ft. above Red Indian Lake, and is reached by a 37-mile private railway from Miller- town Junction. The first ore body found at Buchans was discovered some 30 years ago in the bed of Buchans River, by Matty Mitchell, an Indian woodsman employed by the Anglo-Newfoundland Development Co. Ltd. In the years following the discovery the ore was developed by shaft-sinking and drifting, with results indicating a lenticular ore body in a shear zone, containing about 100,000 tons of extremely fine-grained sulphide ore in barite gangue averaging about 0.05 oz. Au, 4 oz. Ag, 1.5 per cent Ch, 10 per cent Pb, 18 per cent Zn. Because a profitable metallurgical treatment for the ore was not found, the mine was closed down in 1911. In 1915, Mr. H. A. Guess, Vice President of the American Smelting & Refining Co., learned of the Buchans River ore body, and after metallurgical tests had been carried on from time to time in his company's testing plant a satisfactory separation of the sulphides by selective flotation was finally effected in 1925. Prospecting for additional ore bodies was begun in 1926, utilizing geophysical methods under the direction of Hans Lund-

Jan 1, 1937

By J. E. Lawver, J. D. Raulerson, J. P. Bernardi, R. S. Hearon, D. Lynch, G. F. McKereghan

Despite recent economic problems, the future of the Florida phosphate industry appears optimistic. Florida has enormous reserves and will continue to produce a third of the world's phosphate supply simply by making changes in the present system of mining, beneficiation, waste disposal, and land reclamation. The geology and mineralogy of future deposits are discussed with reference to specific deposits. Lower ore grades, increasing power costs, and environmental regulations are necessitating development of new concepts of mining and matrix transportation. Because one of the ores to be mined in the future contains appreciable amounts of dolomite, research and development efforts are being concentrated on new techniques in beneficiation. Changes are being made in plant design to meet environmental and regulation standards. However, the expected new technology outlined for the industry depends on the geology and mineralogy of future reserves.

Jan 1, 1985

By E. M. Wise

THE practice of dentistry, particularly the construction of artificial dentures and "bridges," involves a unique and difficult application of the precious-metal alloys. Appliances used in the mouth are continuously exposed to corrosive agencies which can hardly be described as mild, and must remain free from tarnish and be substantially immune to corrosion. Limitations with respect to space and weight demand high physical properties, while complexity of form requires ease of working. The high corrosion resistance required necessitates the use of alloys of high precious metal content. The usual expedient of resorting to mechanical working to produce the requisite strength and stiffness cannot be utilized because of the frequency of annealing and soldering operations. To meet these difficult conditions manufacturers of dental goods were early led, unknowingly perhaps, to the production of precipitation-hardening or temperable alloys. The excellent properties of iridium-platinum may have suggested the addition of platinum metals to the conventional gold-silver-copper alloys to produce greater strength and hardness. It was found that such quarternary alloys retained their high physical properties after passing through the usual soldering process; i, e., heating to 7500 to 8000 C. and cooling naturally in the air. Later it was discovered that they could be softened and rendered more ductile by heating to the same temperature and quenching, in water. These early examples of precipitation hardening, for years the common knowledge, of dental practitioners and laboratory technicians, escaped the attention of the scientific world and discovery of the transformation which was responsible for this hardening was discovered by the Russian investigators of the system Au-Cu, Kurnakow, Schemtschushny and Zasedatelev,(1) § although the optimum conditions for securing good properties in aged alloys were not given attention.

Jan 1, 1932

By John W. King

Uranium ore was first discovered in the Edgemont district of the southern Black Hills in the summer of 1951. The discovery was not made known for some time, but after the news leaked out prospecting became intense, and several hundred claims were staked in the spring of 1952. The Hot Springs Sub Office of the Atomic Energy Commission was established at that time and airborne radiometric surveys were commenced by the Government and by private companies. During the succeeding summer another important discovery was made by private airborne surveys in the northern Black Hills, and the area favorable for uranium ore was expanded many times. Between that summer of 1952 and the present, many individuals and groups have explored, developed, and exploited their claims until now uranium ore is produced in significant quantities and substantial reserves have been developed. The Black Hills portion of the geologic map of the U. S. issued by the U. S. Geological Survey is shown in Fig. 1. Sedimentary formations are exposed as a series of cuestas and hogbacks in a roughly annular pattern with the older sediments resting on the pre-Cambrian core, which is exposed in the eastern and southern portions of the dome.

Jan 1, 1956