Search Documents

By John G. Hall

MANY millions of tons of raw materials are removed each year from open pit mines in the eastern U. S. These materials are used by industry to produce aluminum, asbestos, barite products, building stone, cement, crushed stone, copper, coal, dolomite, garnet, iron, limestone, mica, phosphate, phyrophyllite, titanium products, and wollastonite. Improvements in open pit mining techniques through the years have made open pit mining more and more attractive as compared to underground methods. Today ore deposits that formerly would have been mined underground have proven to yield more profit if mined by open pit methods. Ever-rising labor and material costs have made equipment capable of high-volume production and low-unit cost-and supplies rendering low-unit costs-not only attractive to open pit operations, but essential to their economic existence. During the past year, the major advances have been in drilling and blasting operations, and the application of large capacity materials handling equipment. Mining men from the Great Lakes, Northeast, East Central, and Southeastern regions of our country tell in the following articles of the trends in open pit mining in their areas during 1956.

Jan 2, 1957

By C. D. Michaelson

Bridging the gap between have and have-not nations is one of the necessities of the present era. The responsibility for accomplishing this must be assumed by the affluent industrial societies of the world, both through their governments and through private enterprise. Despite a discouraging number of instances where companies established in underdeveloped countries have been expropriated, U.S. industry must not abandon such ventures. Instead, it should tailor them to the needs and aspirations of the host nations. One way in which industry can minimize the danger of expropnation is to enter into partnership with the government of the host nation. Kennecott Copper has recently done this in Chile, becoming 49% owner of a company formed to expand and operate the El Teniente mine. So far, the partnership has produced marked benefits not only for Chile, but also for Kennecott. The memory of D.C. Jackling serves chiefly to remind us how much we owe to the pioneers of our industry. Jackling was one of the giants. Orphaned at the age of two, he made his way through sheer persistence and plain hard work. His brilliance gave rise to a vision, and his tenacity made his vision a reality. Foreseeing that economies of scale would make the handling of low-grade ore profitable, he introduced the revolutionary concept of open-pit copper mining. During World War I, the defense effort of the United States was irnrneasurably strengthened by the tremendous supplies of copper from the western mines that Jackling had made possible. Again in World War 11, the demands for copper were supplied, and the nation once more had profound reason to be grateful to this rugged, stubborn man who had long ago ventured into the mountains and unlocked their wealth. We are now embarked upon another great era of change, and we must devise new concepts to meet it. The task is not only to create new techniques of mining, but to forge better ties between men and institutions which will let us work in harmony with the techniques we have. We might recall that while Jackling was a man of towering pride and formidable will, he was also adept at getting others to share his vision and join his purpose. Today our reach for cooperative endeavor must go far beyond our own shores as we seek to develop the buried riches of distant lands. And we would do well to remember that Jackling's remarkable insight would have come to nothing had not British investors been willing to provide much of the initial capital. As was true of so many early enterprises in America, European capital was absolutely essential. CORPORATIONS ABROAD - AN EXPANDING ROLE Today the situation is quite different. The United States is now a capital-surpIus nation and looks abroad for opportunities to employ its capital profitably. On the other hand, we have become dependent on foreign sources for supplies of vital raw materials, while we seek

Jan 1, 1970

By William C. Alden

A great landslide occurred on June 23, 1925, in the valley of Gros Ventre River, about 35 miles south of Yellowstone National Park (Fig. 1). The relations of the north-easterly dipping rock formations of the slide scarp and of the dam formed by the slide are shown in the diagrammatic cross-section of the valley (Fig. 2). This generalized section is based on unpublished maps and notes by Eliot Rlackwelder, in the files of the IT. S. Geological Survey. Heavy rains and melting snow in the Gros Ventre Mountains had saturated clay layers in the Carboniferous strata, which dip toward the valley at angles of 18" to 21°, consequently an enormous mass of rock at the end of the north spur of Sheep Mountain became loosened and, on the afternoon of June 23, slid suddenly down into the valley. Within a few minutes this mass of debris—estimated as 50,000,000 cu. yd.—carrying

Jan 1, 1928

By W. A. Riggs

In a single year the total transportation cost equals nearly 30 pct of the value of mineral commodities, the largest single cost from the deposit to consumer. The magnitude of this economic factor calls for more complete understanding of cost and operational problems between producer and carrier than now exists. Details are given of the costs of providing transportation as well as freight rates for selling transportation. In 1958, transportation of mineral commodities in the United States required 600 billion ton-miles to move 1 3/4 billion tons of products of mines comprising solid fuels, crude oil, industrial minerals and rocks, and ores. Possibly 17 pct was handled by more than one mode of transport, since combinations of several modes of transport may, at times, achieve better service/cost results than any single mode. Total transportation cost of nearly $5 billion equaled roughly 30 pct of the value of the mineral commodities, the largest single cost from the mineral deposit to the consumer. The tremendous magnitude of this transportation undertaking demands much more complete understanding than now exists between mineral producers and carriers about the economic and operational problems of each other. A substantial portion of the daily work of the writer is spent in trying to act as a combination interpreter and catalyst between potential shippers and carriers, hoping to direct both to points of mutual understanding and advantage. For the purpose of this paper, it is necessary to ask mining people to accept some terminology and to try to appreciate the mental approach of the freight rate making people of the carriers. This paper will consider costs of providing transportation as well as freight rates for selling transportation—although these are fields of limited certainty. There are no accurate statistical breakdowns for all modes of transport and types of carriers indicating commodities, volume of traffic, distances, costs, and rates. Much information is available for railroads, and some for the regulated portions of air, motor, pipeline, and water transportation. Unregulated carriers, handling about half of the transportation of products of mines, are not required to report, and very little is known of their activities. Figures used herein are national in scope, unless otherwise indicated, and have generally been derived from Interstate Commerce Commission reports and files. Tonnage figures have been reduced to net tons of 2000 lb. The very generalized comparison of average mileage freight rate levels for various modes of transport provided by Fig. 1 affords advantageous perspective for the entire field of transportation costs. Dashed guide lines show cents per ton-mile, and dotted guide lines show percentage of first class railroad freight rate. While costs of other than railroad transportation more nearly follow constant cents per ton-mile functions, costs of railroad transportation show characteristic taper, or decrease in cents per-ton mile with increasing length of haul. This fundamental difference in cost is due largely to the fact that railroads and pipelines provide their own fully taxed roadway facilities while highway, waterway, and air carriers use government-provided tax-free roadway at no cost other than fuel, license, and certain excise taxes. Thus railroad and pipeline transportation might be said to carry heavy threshold costs in addition to those transportation costs which are directly variable with ton miles of transportation produced. The original basis of railroad freight rate structures lies in the classification of all articles of commerce into railroad class ralings ranging from 7 to 40 pct of first class (100 pct) rate level, dependent on value, hazard, loading characteristics, service requirements, and whether carload or less than carload. Classification tables and mileage-based (but arbitrarily grouped), rate scales are published as tariffs subject to approval by regulatory bodies. Used together, these determine class rates in cents per 100 lb between points in the U. S. Where local commercial or operating conditions render it advantageous for carriers to depart from

Jan 1, 1961

By Walter A. English

CONTENTS PAGE Introduction. By WALTER A. ENGLISH 1 Theory of Seismic Reflection Prospecting. By WILLARD H. TRACY 2 Instruments for Reflection Seismograph Prospecting. By ARTHUR NOMANN 9 Seismograph Field Operations. By FRANK ITTNER 15 Determining Geologic Structure from Seismograph Records. By P. C. KELLY 22 INTRODUCTION BY WALTER A. ENGLISH,* MEMBER A.I.M.E. THE four papers making up this symposum have been prepared espe-cially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathe-matical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismo-graph exploration campaigns would do well to become familiar with as . much as possible of the technical aspects of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1939

Jan 1, 1924

By Arthur Knapp

The practical application of mud-laden fluids in wells has been the subject of many papers.' However, there seems to have been little investigation of what actually happens when mud-laden fluids are applied to a loose porous sand. The assumption is that the fluids penetrate the sands and that there is some plastering action. The degree of penetration and the relation of plastering action to wall stability is not generally known. This paper describes a series of experiments made in an attempt to observe, in laboratory apparatus, the action of mud-laden fluids under conditions simulating those to be found in a well. For the purposes of this discussion all fluids containing solid matter in suspension are mud-laden fluids. Series I: Penetration of the Pores of Uncemented Sands The subject of the penetration of porous formations by water is discussed in detail in Water-Supply Paper No. 67 of the U. S. Geological Survey. No attempt was made to repeat the experiments described therein. The results of the first experiment of this series are given simply to show the capacity of the apparatus used. The conditions in this first experiment were maintained throughout the remainder of this and the second series, except where noted. The experiments of Mills, McCoy, and others on subsurface flows, adjustments, migrations, etc., deal with the oil, water or gas within the porous beds.V he experiments described herein deal with the conditions immediately surrounding the bore hole.

Jan 1, 1923

By Arthur Knapp

The practical application of mud-laden fluids in wells has been the subject of many papers.' However, there seems to have been little investigation of what actually happens when mud-laden fluids are applied to a loose porous sand. The assumption is that the fluids penetrate the sands and that there is some plastering action. The degree of penetration and the relation of plastering action to wall stability is not generally known. This paper describes a series of experiments made in an attempt to observe, in laboratory apparatus, the action of mud-laden fluids under conditions simulating those to be found in a well. For the purposes of this discussion all fluids containing solid matter in suspension are mud-laden fluids. Series I: Penetration of the Pores of Uncemented Sands The subject of the penetration of porous formations by water is discussed in detail in Water-Supply Paper No. 67 of the U. S. Geological Survey. No attempt was made to repeat the experiments described therein. The results of the first experiment of this series are given simply to show the capacity of the apparatus used. The conditions in this first experiment were maintained throughout the remainder of this and the second series, except where noted. The experiments of Mills, McCoy, and others on subsurface flows, adjustments, migrations, etc., deal with the oil, water or gas within the porous beds.V he experiments described herein deal with the conditions immediately surrounding the bore hole.

Jan 1, 1923

By Floyd C. Kelley

THE literature of the last decade is rich with information relating to the cause and means of control of grain growth in pure metals, but is deficient concerning the role diffusion plays in grain growth, although during this period many new products that depend on diffusion for their properties and success have been developed. Among these are cementation products, produced by calorizing, chromizing, and carbonizing, or by mixing, pressing, and sintering powdered metals such as Syke's iron-molybdenum die material, Genelite, and Elcon Metal (copper, tungsten) etc. This is a fertile field for new developments, but before it can be utilized to the fullest extent there must be a thorough investigation of the processes by which diffusion and grain growth take place. Grain growth plays no small part in the process and certainly the physical properties of these products depend largely on the grain size and state of equilibrium produced. The field of investigation does not end here, but may be extended to the effect of diffusion on impurities, segregations and dendrites in the broad field of ferrous and non-ferrous metallurgy. A number of years ago the author investigated several of these cases and noted, with striking regularity, the pronounced effect of diffusion in promoting recrystallization and grain growth. An example of this phenomenon is given in his paper on chromizing1 which contained photomicrographs of large radial or columnar crystals produced by diffusion of chromium in the solid state. Another manifestation of this effect was discussed by Austen,2 who showed the part hydrogen plays in the decarburization of steel and the effect of diffusion upon the grain structure. DIFFUSION OF METALS IN IRON It seems to be a general law, whenever two metals are brought into intimate contact at a temperature at which diffusion takes place, that a comparatively rapid, or abnormal, grain growth results. The grains

Jan 1, 1928

By David R. Mitchell

THIS paper is limited primarily to a description of dry coal-cleaning processes in which air currents are used to effectuate a separation between coal and refuse. Processes depending mainly on differences in the coefficient of friction, resilience and shape are not described unless the use of air is necessary for the proper functioning of the process. The air cleaning of coal is of primary importance to the coal industry of the United States. From figures presented in the 1941 edition Mechannual,1 it is estimated that at least 12 million tons of bituminous coal was cleaned in the United States during 1940 by machines using air as the separating medium. One of the current problems confronting the coal-preparation engineer is the dry cleaning of small sizes and slacks. Progress in machine development for the cleaning of small sizes has been slow in recent years in the United States of America; it has been much more rapid in Britain and on the European continent. This paper does not attempt an exhaustive survey of all these developments, and only machines and processes that have found considerable commercial application are cited. Further, no critical analysis has been made of the theory involved in the separation of coal from refuse by processes using air as the separating medium other than that necessary for an understanding of particular machine designs and applications. HISTORICAL SUMMARY The possibility of using air for the separation of coal from refuse was recognized early by mining men and many attempts were made to develop commercial machines. The ingenuity of the early experimenters is to be marveled at in view of their lack of knowledge of the theoretical principles involved. As in other arts, practice has largely preceded theory. Yet, science and practice play a game of leap frog, now one ahead, then the other; the careful experimenter governs his efforts along practical lines by adapting his experiments to the limits prescribed by scientific laws. By first studying developments and the theory involved, it is not only possible to adapt processes to new uses but also to reduce materially operating cost and to build larger units without costly failures. Although many inventors have applied for patents for separating minerals by the use of air currents, the literature in regard to coal is meager. Berrisford2 describes briefly some of the early attempts to clean coal without the use of water. Several of the examples cited by him are reproduced herein. Fig. I shows a machine used for grinding and sizing, in which rollers running in a pan with a perforated bottom and fan opening on the side crushed the coal, which was then carried by the air currents to a settling chamber. The heaviest particles dropped out first and the light ones farthest away, as shown. In the year 1864, a machine was made that could be used as a sizer or to separate dirt from coal with a sized feed (Fig. 2).

Jan 1, 1942

By C. Dalton, H. L. McGill

The purpose of this study was to develop a method for predicting the time delay created by metering a fluid through an annular restriction with translational motion of the boundaries. This time delay is utilized to control the opening of valves in various down-hole oilfield tools and forms the basis for the "hydraulic jar". The hydraulic jar is used to give upward impact forces to tubing or other tools that become lodged down-hole. The design of these jars has primarily been by trial and error; varying the clearances, fluid viscosities and dimensions of the jar until a satisfactory time delay was achieved. Obviously, a better understanding of the fluid flow characteristics is required to produce designs that are satisfactory and to eliminate the trial-and-error approach. Previous studies of flow in annular spaces were based on constant length of the annular restriction. Any motion of the boundaries of the annular space was confined to a rotational motion, like that encountered in journal bearing design. Consideration of the effect of translational motion of one boundary with respect to the other was necessary in applying this previous work to a time delay device. A prediction method was developed that takes into account this relative translational motion. Equations were developed to predict the relative velocity, the flow rate, and the time delay in a concentric annular space. The effect of eccentricity also was included. Experimental data were obtained and closely correlated with the prediction method. This correlation is presented graphically in terms of predicted and actual relative velocities for various annular clearances and pressure drops. This extension provides design equations which predict the performance of the hydraulic jar, thereby eliminating trial-and-error solutions and reducing the development time required for satisfactory designs. INTRODUCTION The design of down-hole oilfield tools which use hydraulic delay systems based on flow through annular orifices with relative motion of the boundaries is usually a trial-and-error process. The annular clearances, fluid viscosities and dimensions of the mechanisms were varied until satisfactory delay times were obtained. The development of these tools has been expensive, and a better understanding of the characteristics of annular flow with relative motion of the boundaries could result in superior and less expensive designs. The purpose of this investigation was to provide a method of predicting the performance of down-hole tools which use annular flow and, in particular, the performance of a down-hole tool known as the "hydraulic jar". The hydraulic jar is used to free pipe, packers and other tools that become lodged down-hole. The jar, located in the tubing string between the surface and the object which is stuck, releases the object though the repeated application of upward impact blows. The jar is basically a slip joint that is restrained in a collapsed condition until the desired tubing tension has been developed. The slip joint is then released and accelerates rapidly until it shoulders, delivering an impact blow or jar to the object. The delay obtained by metering the fluid through the annulus formed by the jar valve and housing provides the time delay necessary to stretch and apply tension to the tubing or pipe. Fig. 1A gives a schematic diagram of the hydraulic jar and brief details of its operation. The metering of the hydraulic jar begins when the tension force being applied to the jar by the pipe creates a pressure differential across the valve that is approximately equal to the force divided by the displacement area of the valve. This pressure differential induces flow through the annular restriction formed between the valve and housing. The valve moves with respect to the housing as the

Jan 1, 1969

By Luis Salazar

Internal improvements are the great seals; stamping upon the history of nations their epochs of peace, in which notable enterprises are conceived, and fresh impulses given along the path of progress. Such forerunners of national benefits have never been so notable in Mexico as in the last four decades of the nineteenth century, during which the national faith in the consolidation of peace has been a guaranty of the development of all the elements of national prosperity. Among all the improvements which have been realized with the unanimous approbation of the people, the railroads occupy a preferred place, for upon them depends the expansion of commerce, of agriculture and of mining, the three great factors of the wealth of Mexico. In a country so extensive as the Mexican Republic, where the inhabitants are greatly scattered, and great distances separate the producer from the consumer, the only way to encourage home industry, and the development of commerce, agriculture and mining, is to construct railroads, which shorten distance, facilitate transportation and minimize its costs. The mountainous character of the country makes the navigation of its rivers practically impossible, except very near to

Jan 1, 1902

By Alden B. Greninger, Victor G. Mooradian

Microscopic examinations of quenched (beta) 60:40 copper-zinc and quenched (beta) 74:26 copper-tin alloys have frequently disclosed long, thin parallel bands or markings within the polyhedral beta grains. Apparently, it has been accepted that these markings are mechanical twin bands, although there is no published account of experimental data that might tend to substantiate this belief for the copper-zinc system, and only meager evidence has been submitted for the copper-tin system. Johnsonl0 commented upon the markings he observed after deforming a quenched brass of 55.6 per cent copper and 44.4 per cent zinc. Clark's papers4 on the heat-treatment of Muntz metal contain many photomicrographs of markings in beta brass; these she referred to as Neumann bands (inasmuch as repolishing and re-etching failed to remove them) and stated that markings present in Muntz metal as quenched were the result of shock imparted during the polishing operation. Van Wert18 first suggested that these parallel markings in quenched beta brass (60:40) might be alpha precipitated along certain crystallographic planes of the matrix lattice. He showed that upon reheating the specimens to temperatures below 800" C., obvious precipitation of alpha within the large beta grains first occurred at the markings. In a discussion of this paper, Phillips stated (pp. 505-507) that in his opinion the markings observed by Van Wert were mechanical twins resulting from contraction strains produced during the quenching operation. In a study of segregate structures in beta copper-tin, Smith17 observed that in the quenched beta phase (containing 74.92 per cent Cu) parallel . bands or markings very similar to those in metastable beta brass could be

Jan 1, 1938

By Alden B. Greninger, Victor G. Mooradian

Microscopic examinations of quenched (beta) 60:40 copper-zinc and quenched (beta) 74:26 copper-tin alloys have frequently disclosed long, thin parallel bands or markings within the polyhedral beta grains. Apparently, it has been accepted that these markings are mechanical twin bands, although there is no published account of experimental data that might tend to substantiate this belief for the copper-zinc system, and only meager evidence has been submitted for the copper-tin system. Johnsonl0 commented upon the markings he observed after deforming a quenched brass of 55.6 per cent copper and 44.4 per cent zinc. Clark's papers4 on the heat-treatment of Muntz metal contain many photomicrographs of markings in beta brass; these she referred to as Neumann bands (inasmuch as repolishing and re-etching failed to remove them) and stated that markings present in Muntz metal as quenched were the result of shock imparted during the polishing operation. Van Wert18 first suggested that these parallel markings in quenched beta brass (60:40) might be alpha precipitated along certain crystallographic planes of the matrix lattice. He showed that upon reheating the specimens to temperatures below 800" C., obvious precipitation of alpha within the large beta grains first occurred at the markings. In a discussion of this paper, Phillips stated (pp. 505-507) that in his opinion the markings observed by Van Wert were mechanical twins resulting from contraction strains produced during the quenching operation. In a study of segregate structures in beta copper-tin, Smith17 observed that in the quenched beta phase (containing 74.92 per cent Cu) parallel . bands or markings very similar to those in metastable beta brass could be

Jan 1, 1938

By Arthur Notman

SacRamento Hill is a mass of granite porphyry intruded along a fault between Paleozoic sediments and pre-Cambrian schists in the Bisbee district, Cochise County, Arizona. The intrusion invaded both walls of the fault to a large extent, and the accompanying extensive mineralization of the Paleozoic limestones is the locus of the great high-grade copper orebodies of the Bisbee mines. Prior to 1909, although the presence of ore in the masa of the hill itself had long been suspected, systematic exploration had not been attempted. A few shallow pits on the surface here and there had disclosed some chal-cocite with associated carbonates as stringers in a mass of strongly brccciated, silicified, and iron-stained porphyry. The workings in the surrounding limestones had penetrated the porphyry in a dozen or SO places for some distance from the contact but had disclosed no ore. However, the rock had been largely altered to quartz and sericite and very thoroughly impregnated with pyrite and traces of the copper sulphides. A close geological study of the conditions, both surface and underground, strengthened these suspicions, and plans for prospecting the hill were made in 1909. Reference to the accompanying illustrations, Figs. 1 and 2, will give an idea of the general appearance of the surface. The mineralization is more intense in two main zones, one at the west end and the other at the east end of the hill. The outcrop of the hill is elliptical and approximately 3,000 ft. long by 1,400 ft. wide. The Sacramento shaft, which is the main hoisting shaft of the mine and situated at the east end of the hill, as shown by the accompanying map (Fig. 3), offered a convenient base for prospecting that end of the hill, while the workings from the Holbrook shaft offered a similar opportunity at the west end. The choice of level for the first work was determined by analogy with the most favorable depth for enrichment below surface obscrved in the other disseminated deposits of the Southwest.

Jan 1, 1916

By John Drew Ridge

For the early conservationists before the first decade of the twentieth century, conservation meant largely the planned preservation of water, forest, soil, and wildlife resources-renewable natural resources-through efficient use. Water was primarily thought of as a resource that must be kept available for humans to enjoy in a recreational sense and as a habitat for wild animals, birds, and fish. Little thought was given to conserving water for actual human or industrial needs. If industry entered the picture it was as an actual or potential polluter of water, which was the basic necessity for drinking and bathing and for outdoor recreation. Even the forests were only held worthy of conservation largely because they were areas in which wildlife could, or should, abound and in which human beings might find relief from the cares and problems of everyday life. Finally, the soil was to be preserved in its natural fertility through proper fertilization, cultivation, and crop rotation; in this the conservation program did enter the realm of the practical. For through soil conservation, the world was to be able to raise increasingly large crops of constantly improved organic foods which the steadily growing population of the earth was to need to survive and improve. Relatively little time, however, was spent on considering what profit the farmers of the world were to make from the scientific farming on which they were to embark. In short, the appeal of the early conservationist program was much the same as that of the entire era of Theodore Roosevelt of which it was a part; it was to the heart rather than to the mind; it was to emotion rather than to reason. Because of the way in which the problem was approached, conservation took on the character of a crusade rather than that of a practical plan for the betterment of man through economically sound methods of improving his environment and the uses he makes of it. Conservation had, then, all the advantages of a stirring appeal to the emotions, but it did not have the lasting results that would have been achieved by a program with a sound economic basis.

Jan 1, 1959

By W. R. Foster, J. M. McMillen, A. S. Odeh

The complete equations of average linear momentum balance for a single-phase fluid in an incompreisible, homogeneous, porous medium are derived. The derivation begins with Euler's equation of motion for a continuum and uses an integral transform recently developed by Slattery. 7 For steady flow of a compressible, Newtonian fluid, the usual equations of motion result. For transient flow, the space-time description of the pressure is determined in the lowest approximation by the telegrapher's equation. From the analysis a new phenomenological coefficient results which connects the viscous traction to the deriv ative of the linear momentum density. The magnitude of this coefficient determines the velocity of sound through the pore structure in this approximation to the pressure field. INTRODUCTION The modification of Darcy's law of momentum balance for steady, single-phase flow through porous media has been discussed for many years. The first modification was suggested by Forcheimerl who added terms of higher order in the velocity. These can be expected to appear because the underlying microscopic equations of momentum balance are themselves nonlinear in the point velocity field. The Reynolds tensor pvv, which represents the convective flux of momentum density, appears in the momentum balance equation. Only in rectilinear flow (parallel stream lines) does the divergence of this tensor vanish. Since the steady flow stream lines in most porous media are not parallel, nonlinear dependence of the pressure gradient on the velocity should naturally appear. This nonlinearity has nothing to do with turbulence in the ordinary sense of random fluctuations in the pressure and velocity fields. It arises simply because the stream lines converge and diverge, even for steady flows. Klinkenberg2 demonstrated that the permeability coefficient in Darcy's law depends on the absolute pressure or, alternatively, on the density field. However, because he neglected inertial terms of the Forcheimer type, his correction coefficient could not be represented by a constant but tended toward a constant as the velocity decreased. Forcheimer's and Klinkenberg's modifications can be combined in a rigorous way to account for both inertia and slip during steady flow. This will be shown in a future paper. The transient change of pressure in porous media has been described by the diffusion equation.3 This form results from eliminating the velocity and density fields from a combination of the equations of motion in the form of Darcy's law, the continuity equation and an equation of state. Fatt4 suggested that the cause of deviations from the prediction of the diffusion equation for pressure transients lies not in the choice of Darcy's law as the equation of motion but on the existence of dead-end pores which might invalidate the averaged equation of continuity. On the other hand, Oroveanu and Pascal5 noted chat the time derivative of the momentum density must be included in the equations of motion since this measures the local rate of change of momentum density. Their differential equation for pressure is the telegrapher's equation (neglecting gravity). However, their form of this equation predicts that the speed of pressure propagation through the pore structure is the same as that through the bulk fluid. M. K. Hubbert6 attempted a derivation of Darcy's law by volume averaging the Navier-Stokes equations. Since these equations represent momentum balance at a point within an open set of points containing the fluid itself, Hubbert's volume averaging cannot lead to tenns involving transfer of momentum between the fluid and the walls of the pores. Once these viscous tractions are lost by choosing a control volume containing only fluid, they cannot

By C. R. Johnson, R. A. Greenkorn, R. E. Haring

Three confined five-spot miscible displacements at unity, favorable, and unfavorable mobility ratios were conducted in a shallow, water-saturated sandstone of Pennsylvan-ian age near Chandler, Okla. These studies, plus associated laboratory experiments, were designed to measure miscible displacement performance in a controlled natural system, using known scaling criteria to develop an approach to modeling the heterogeneous field system. We have concluded from these studies that: (I) displacement efficiency in the field is a pronounced function of mobility ratio, indicating that miscible fingering observed in simple laboratory models occurs in the field: (2) field displacements can be quantitatively predicted by scaled laboratory models if the degree and location of field permeability variations are preserved in the models: and (3) arbitrary simplifications of heterogeneity will not necessarily predict observed displacement efficiency, and the simpler the model, the more optimistic the prediction. INTRODUCTION Many processes to achieve miscible displacement of reservoir oil by injected fluids have been conceived and field tested by the oil industry. Among the better known are high-pressure gas, enriched gas, and LPG banks. The simplest form of miscible displacement—one fluid miscibly displacing another fluid of different viscosity but the same density—has been studied extensively in homogeneous laboratory models. Observations of unstable fingering have been made which explain the significant decrease in displacement efficiency as the mobility ratio (ratio of displacing fluid mobility to displaced fluid mobility) increases. General industry experience with field tests of miscible displacement projects, mostly LPG banks, has been premature solvent breakthrough and lower than predicted production rate increases. These results have been attributed to either unstable fingering, unusual or unexpected permeability stratification, or both. Miscible displacement data in a controlled natural system have never been reported, however. Also, it has not been shown that properly designed and constructed laboratory models quantitatively predict field-scale behavior. The purpose of the combined field and laboratory ex- periments reported in this paper is twofold. The first was to measure miscible displacement performance at different mobility ratios in natural rock approaching field size under precise, controlled conditions. The second purpose was to utilize known scaling criteria plus several approaches to heterogeneity to model the field. Comparison of model and actual field results should then determine whether or not the laboratory phenomena (manifested by miscible displacement efficiency) are exhibited in large, natural rock systems. We carried out our program by first locating a shallow, water-saturated reservoir whose rock properties were representative of oil-bearing reservoirs. Detailed reservoir description by core analysis and interference testing showed the field site to be heterogeneous. A sequence of controlled, aqueous-phase miscible displacements was conducted at unity, favorable and unfavorable mobility ratios. A central, confined pattern was used to obtain the displacement data. A laboratory program using sand-packed models was conducted to determine the modeling criteria necessary to simulate field behavior of miscible displacement in a heterogeneous system. SCALING THEORY The detailed derivations and descriptions of the scaling laws that apply to laboratory models of reservoirs are adequately described elsewhere, so the following discussion will be restricted to facets of importance in this study. For a displacement in which one liquid miscibly displaces another, the following dimensionless groups are required to have the same numerical value in the model as in the field: The model also must be geometrically similar to the field, be spatially oriented the same as the field (same dip angle), and have the same initial and boundary conditions as the field (same initial fluid saturations and same injection-production well arrangement). When these conditions are satisfied, the theory predicts that at dny dimensionless time (pore volumes of produced fluids) the dimen-sionless flow potential and dimensionless fluid concentrations will be identical at all dimensionless spatial locations within the model and the field. If this prediction is correct, then the local dimensionless velocities must be identical, thus the instantaneous fraction of displaced fluid produced and the cumulative recovery expressed as fraction of original fluids in place must be identical at all dimensionless times. The theory outlined above has been obtained by either dimensional analysis or inspectional analysis of differential

Jan 1, 1966

By A. L. Titchener, M. B. Bever

The stored energy of cold work was investigated in drawn gold-silver wires by tin-solution calorimetry as a function of strain, strain rate, initial grain size, and temperature of defornation. The energy expended in the deformation process was measured. Hardness was also measured and was correlated with the stored energy as a function of strain and strain rate. Mechanisms of energy storage are discussed. THE variables which determine the amount of energy stored in a metal during cold work are of two kinds: those involving the metal and its condition and those involving the process of deformation. For example, the stored energy differs between one metal and another and between different degrees of purity of a single metal. It also depends on the nature of the deformation process and particularly the extent, rate, and temperature of deformation. Most investigators have reported the stored energy as a function of strain (or some similar geometric parameter) or of the energy expended during deformation. In general the stored energy increases with strain, rapidly at first, but more slowly at large strains until a saturation level is reached. Information about the effects of other variables, however, is limited. Some data are available on the dependence of the stored energy on the purity of a metal1 and on the composition of

Jan 1, 1960