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By Bartlett W. Paulding

Since its introduction to the petroleum industry in 1949 by Clark,1 hydraulic fracturing or "hydrafracing" has developed into a widely respected and useful technique for increasing production from petroleum reservoirs. Even then, Clark described production increases of from 6 to 100 barrels of oil per day (bopd). Since that time, others have described treatments in which production increased from 12 to 456 bopd, from only a show to 40 bopd;2 from 48 to 219 bopd; 3 from 500 to 1400 bopd and from a show to 192 bopd.4 Although representative of only a few of many successful hydraulic fracturing operational6 these increases in production attest to the past and potential value of the hydrafracing technique to the petroleum industry. The technique has received a considerable amount of theoretical and experimental attention.1, 5-20 Unfortunately, however, the degree of general understanding of the mechanics of hydraulic fracturing is still inadequate to solve many recurring problems. The practicing engineer is plagued with difficulties in predicting such factors as: (1) the required pressure and viscosity of the fracturing fluid to not only induce the fracture but to control the extent of its growth, (2) the strength characteristics and amount of proppant to include in the fluid so that the fracture is held open once the fluid pressure is decreased, and (3) the volume of the reservoir influenced by the induced fractures and the resulting increase in production. A major cause of these difficulties is the uncertainty associated with determining the orientation of the hydraulically induced fractures. One's natural conclusion in considering the problem is that the orientation of the fracture would depend on several variables, as, for example, the relationship between the viscosity and injection rate of the fluid and the

Jan 1, 1968

By R. L. Slobod, H. A. Blum

A semiquantitative method for measuring the wettability of reservoir rocks has been developed. These data are needed for reservoir analysis and for interpretation of laboratory displacement studies. The wettability of a core sample is measured by the contact angle for the system oil-water-solid. These contact angles are calculated from the displacement pressure (threshold pressure) obtained by use of the centrifuge, using first oil-water and second air-oil in the same core sample. This method is based on the assumption that the air-oil and oil-water interfaces occupy similar positions in the porous medium when desaturation of the wetting phase is initiated. The assumption is also made that the Contact angle for the air-oil-solid system which is close to zero in value does not change appreciably even when the contact angle for the oil-water-solid system experiences marked changes. "Apparent contact angles'' for five different solids ranging from 31" to 82" have been determined, and changes irr the "apparent contact angle" of a given sample with laboratory use from 33" to 53' {lave been observed. INTRODUCTION Reservoir rocks vary in their wettability, 1,2,3,4 some being preferentially water wet while other are apparently preferentially oil wet. The degree of wettability, in theory, is measured quantitatively by the contact angle for the system solid-oil-water, hut in 1)practice this quantity is extremely difficult to determine." The need for obtaining some measure of this quantity has become obvious in recent years as a result of both laboratory. and field observations. Several reservoir.: such as the Bradford Sand in Pennsylvania and the Wilcox' at Oklahoma City are reported to be oil wet. If these report:: correctly reflect the true nature of the surface of the rock in the ground, then these reservoirs probably will not perform as predicted on the basis of a water wet rock. In the laboratory many core samples have been Observed to be oil wet. These samples, while perhaps not correctly representing the reservoir, have markedly different properties from water wet rock. The location of the phases is different (oil is in contact with rock instead of water), and other quantities such as the connate water, the capillary pressure curve; residual oil. relative permeabilities. and the recovery of oil by water flooding are markedly affected by the value of the contact -4 A further complication observed in the laboratory is the chang-ing of the wettability of a rock specimen with use. such changes mean that repeat runs on the same core are not the duplicate tests desired, but represent new experiments on a more oil wet material. The changes in surface characteristics are sometimes so rapid that by the time an experiment requiring several days is completed, the results may not be representative of the core as originally described, The, rock material itself (Silica. carbonates. etc.), whell Clean and uncontaminated, is water wet. There seems b( : little evidence of the presence of oil wet minerals such as heavy metal sulfides. The oil wetness of reservoir samples, therefore, is believed to be caused by the accumulation of an adsorbed film in which the polar group of a large organic. molecule is adsorbed on the surface leaving the organic or hydrocarbon part of the molecule projecting out from the solid. Such a surface is much more readily wet 17" oil than by water. These considerations indicate the need for a method which will provide some measure of tile wettalbility (Contact(angle if possible) for reservoir rock ..samples) The method should be capable of (1.1 distinguishing between tile wettalility of dif. ferent formation,.. (2) detecting (change. ill wettalbility of a core with use. and (3) measuring the changes in Wettability which may be accomplished with cleaning operations. such as the use of sodium silicate for increasing water wrettalbility." A preliminary report on such a method is preseted below. not with the idea that this procedure alone will Solve the wettabil-ity problem. but rather that it may provide encouragement to

Jan 1, 1952

By Gifford White

Considerable attention has been directed in recent years to methods of electric prospecting other than the conventional direct-current techniques. It has been extensively recognized that electrical data of a more general nature than that possible by direct-current methods might be useful in geophysical studies. To this end, a number of different types of electric currents have been employed, such as single-frequency alternating currents, square-topped periodic current waves,4 periodic surges of a less specific nature,s and suddenly applied direct current.1,2 Yet, to the author's knowledge, little analysis of these different types of driving currents has been made from the standpoint of network theory to determine just what typc of currents would give the most useful data, and, most important of all, to determine the relation of the data taken by one method to those of another. Without touching on the actual theoretical problem of how currents flow in the earth under specified boundary conditions, some very useful information can be obtained from the study of the fundamental integral equations of electrical networks, throwing light on the problem not ordinarily appreciated by the field worker. Some manipulation of the standard network equations will be made, with the sole purpose in mind of developing expressions leading to practical results. Suppose that four points in the earth have been located and it is wished to obtain the most useful type of electrical data by inserting current into two of them and measuring the potential developed between the other two. The first problem that arises is that of which pair of the four shall be chosen as current grounds. In the direct-current case, where only steady potentials are measured, the selection is of little consequence, but as soon as currents varying with time are used at the current grounds, a new effeet arises. The fact that a varying current is flowing in the current-carrying conductor between the current grounds means that magnetic and electric fields varying with time will be produced

Jan 1, 1940

By Gifford White

Considerable attention has been directed in recent years to methods of electric prospecting other than the conventional direct-current techniques. It has been extensively recognized that electrical data of a more general nature than that possible by direct-current methods might be useful in geophysical studies. To this end, a number of different types of electric currents have been employed, such as single-frequency alternating currents, square-topped periodic current waves,4 periodic surges of a less specific nature,s and suddenly applied direct current.1,2 Yet, to the author's knowledge, little analysis of these different types of driving currents has been made from the standpoint of network theory to determine just what typc of currents would give the most useful data, and, most important of all, to determine the relation of the data taken by one method to those of another. Without touching on the actual theoretical problem of how currents flow in the earth under specified boundary conditions, some very useful information can be obtained from the study of the fundamental integral equations of electrical networks, throwing light on the problem not ordinarily appreciated by the field worker. Some manipulation of the standard network equations will be made, with the sole purpose in mind of developing expressions leading to practical results. Suppose that four points in the earth have been located and it is wished to obtain the most useful type of electrical data by inserting current into two of them and measuring the potential developed between the other two. The first problem that arises is that of which pair of the four shall be chosen as current grounds. In the direct-current case, where only steady potentials are measured, the selection is of little consequence, but as soon as currents varying with time are used at the current grounds, a new effeet arises. The fact that a varying current is flowing in the current-carrying conductor between the current grounds means that magnetic and electric fields varying with time will be produced

Jan 1, 1940

By C. W. Hall

Owing to its isolation and comparatively small tonnage, the Yoquivo district is not widely known; though financially important and, geologically, quite interesting. San Francisco dc Yoquivo, the center of the mining district, is in the western part of the state of Chihuahua, Mexico; about 35 miles west of. San Juanito, on the Kansas City, Mexico & Orient R. R. The town can be reached from the railroad by a good trail over a rugged country. The elevation of Yoquivo is 6500 ft., and peaks surrounding the town are 2000 ft. higher. The mining towns of Concheno and Ocampo are 25 miles northwest, and Uruachic is 20 miles southwest. The climate, temperate and healthful, is almost ideal. The rainy season begins in July and ends the latter part of September. There is usually, though not always, some precipitation in all months except April, May, and June: The mountains are covered with pine and scrub oak. Water, wood and lumber are plentiful for all ordinary purposes, and hydroelectric power is available for. about six months of the year, when wood for steam, power is utilized as an expedient. The district has been worked: recurrently for over 60 years. The Yoquivo province lies on the steep western-slope of the Tara-humara division of the Sierra Madre range of mountains. The province is traversed by many deep canyons, most of which flow west. The town is situated on the San Francisco arroyo, which makes a confluence with the Huevachic stream 212 m. southwest; the Huevachic in turn joins the Candemeña river farther down and these two drain the western flank of the Tarahumara mountains and form the headwaters of the Mayo river. The claims of the Yoquivo Development Co., which, is the only organization in the district with a record of any considerable production,: lie within an area roughly 112 m. square. The area extends from the, San Francisco arroyo north, and from the Dolores arroyo west, and is confined to the andesitc formation.

Jan 2, 1926

By P. C. Hodges

While there is very little romance connected with the operation of a stone quarry, yet to those who have participated in the growth and development of a business that has been a pioneer in its field and that has been in continual operation two-thirds of a century there is bound to be a background of experience, which if properly capitalized, brings progress as well as satisfaction in its accomplishment. The simple methods of drilling and blasting limestone and loading on to railroad cars everything that remained on a stone fork and leaving

Jan 1, 1936

By P. C. Hodges

While there is very little romance connected with the operation of a stone quarry, yet to those who have participated in the growth and development of a business that has been a pioneer in its field and that has been in continual operation two-thirds of a century there is bound to be a background of experience, which if properly capitalized, brings progress as well as satisfaction in its accomplishment. The simple methods of drilling and blasting limestone and loading on to railroad cars everything that remained on a stone fork and leaving

Jan 1, 1936

By A. P. Boller

In the victories of peace as well as of war, the science of engineering has played a prominent, if, indeed, not the leading part. While it might be interesting, and food for profitable thought, to trace the development of engineering from early times in its bearings upon the social betterment of mankind, it will be sufficient on the present occasion to suggest a few thoughts that it is hoped will aid the unprofessional listener to an appreciative consideration of the subject-matter laid down for to-day's discussion, and possibly lead the professional brother to a higher conception of the profession to which he belongs. Since the advent of the railway era, it is difficult to grasp the sequence of historic events that have led to the wondrous derelopment of mechanical science, making possible the civilization that is our daily boast, and opening up a vista of future intellectual and moral advancement among the nations of the earth, 'before which the imagination becomes hopelessly lost. Even now, looking back over a period of only half a century, we often fail to realize the vast change in the relations of individuals and nations to each other., brought about by the results of those mechanical discoveries which, having made the whole world kin, exercise a resistless levelling influence that bears fruit politically in the spread of republican ideas, and morally in the elevation of the individual through the facilities given to the dissemination of Christian ideas and general intelligence. In this view, it seems almost like a work of supererogation for a body of representative men of one department of that science to which the whole world owe. so much, to meet here at the centre of our national life to plead not only for a practical recognition of the national importance of the work to which their lives are devoted, but also for national aid, on a scale beyond that of private effort, to the end that mechanical science may be carried to a higher plane than ever yet attained, each step on the way being of material benefit to every man, woman, and child in the community. Possibly this is strong language, but none too strong when we consider that the work for which we plead is one affecting not only vast scientific and commercial interests, but also human life, to a degree little ap

Jan 1, 1882

By C. N. Kravig

STANDARD raises at Homestake are 150 ft long. Raises of more than 150 ft, driven with the use of a cage and hoist, are considered long raises- some have been driven more than 900 ft. Long raises have eliminated the need for access drifts on each level when transfer and ventilation raises are driven. These timbered cage raises, 7x9 ft in cross section, include a rock compartment and a combination cage, pipe, and manway compartment. To prevent excessive weight on the timbers, 10x10-in. bearing beams are cemented into hitches cut in the rock at 150-ft intervals. The beams also hold back timber movement caused by daily drawing of rock through the rock compartment.

Jan 6, 1957

By E. F. Bradley, R. I. Jaffee, H. R. Ogden, E. S. Bartlett, D. N. Williams

The mechanical properties of solid-solution-strengthened columbium alloys have been assessed as a function of alloying additions. Studies included the effects of tungsten, tantalum, molybdenum, and vanadium. Elevated temperature fabrication was required at alloying levels above about 15 pct W or 10 pct Mo. Tungsten, molybdenum, and vanadium additions increase tensile strength at room temperature and 2200°F, but tantalum additions exert little strengthening. Similarly, tungsten, molybdenum, and probably vanadium additions increase the ductile-to-brittle transition temperature, and tantalum additions decrease this parameter. The 2200°F stress-rupture strength is increased by tungsten and molybdenum additions; with 20 to 25 at. pct additions, 100-hr rupture strengths of 30,000 psi are obtainable. Small vanadium additions exhibit mild stress-rupture strengthening, and tantalum additions are innocuous. At 2500°F, tungsten additions retain stress-rutpure strengthening capability, but molybdenum additions are much less effective. Tantalum additions augment the stress-rupture strengthening of tungsten plus molybdenum additions at 2500°F. Of the refractory metals, columbium possesses specific potential for structural use in the temperature range from 2000" to about 2500°F. Desirable features of columbium are its good low-temperature ductility, ease of fabrication, oxidation mechanics (lack of a volatile oxide at moderate temperatures), good availability and reserves, and relatively low density. However, alloying is required to provide attractive strength at elevated temperatures. Published information concerning alloying be- havior of columbium relative to mechanical properties is sketchy, particularly in consideration for long-time applications at temperatures in excess of 2000°F. Only a few stress-rupture data at temperatures from 2000" to 2500°F have been reported;'-' these are too meager to allow rationalization of the effects of various alloying additions on creep or stress-rupture properties. Additional published data do, however, give some insight toward understanding of systematic alloying behavior for columbium relative to low-temperature strength4-' and ductility,' and elevated temperature tensile behavior.4,6 This paper is intended to augment previous knowledge, and to promote understanding of the alloying behavior of columbium for long-time structural service at elevated temperature. BASIC CONSIDERATIONS Solid-solution strengthening is recognized to be of prime importance in improving strength in columbium-base alloys. Other strengthening mechanisms may be (and are, in current alloys) used to augment solid-solution strengthening. As strengthening results primarily from lattice distortion, the strengthening effectiveness per atom depends upon atomic size mismatch between solvent and solute. Another factor in this regard is conformance to ideal solution behavior in the solid solution. Thus, for example, despite appreciable differences in the degree of mismatch between tungsten (5 pct), molybdenum (5 1/2 pct), and vanadium (7 1/2 pct) in solution in columbium, all are about equally effective in straining the columbium lattice at room temperature.'-' Similarly, tantalum additions do not strain the columbium lattice, and little strengthening is expected. Size effects being equal, maximum solution strengthening at high temperatures is anticipated to result from the addition of elements that increase the melting temperature of columbium. This expectation is based on an increase in the electronic bonding forces exhibited in the transition metal series as electronic structures approach those of the Group Vl metals. Of the metals that exhibit ex-

Jan 1, 1963

By M. D. Hassialis

[Surface Areas of Concentrates and Collector Coatings (T.P. 2002, by A. M. GAUDIN and G. S. PRELLER, Min. Tech., May. Discussion by M. D. HASSIALIS and the authors) . I Activation of Minerals and Adsorption of Collectors (T.P. 2082 by J. ROGERS and K. 1'. SUTHERLAND, Min. Tech., Nov. Discussion by A. F. TAGGART and the authors). . . . 3 Correlation between Mineral Behavior in Cataphoresis and in Flotation (T.P. 2005 by A. If. GAUDIN and S. C. SUN, Min. Tech., May. Discussion by M. D. HASSIALIS). . . . . . 8] Surface Areas of Concentrates and Collector Coatings M. D. HASSIALIS.*-In the current flotation theories there exists a common gap spanned by a common assumption pertaining to the arrangement and orientation of the collector ions at the solid surface. Also common is the belief that contact angle and flotation performance are dependent upon the arrangement and orientation of collector ions. This stimulating and informative paper sheds some light upon this general problem. One of the indices of arrangement is the area available per collector ion; in this connection, Gaudin and Preller have applied the B.E.T. method for surface determinations. In a surprising number of cases, their results show a greater specific surface for tailing than for concentrate. This cannot be accounted for by the differences in specific gravity and is attributed to the presence of clay minerals of "primary" sluices in the tailing. This is not a satisfactory explanation, for experience shows that when free slimed clay minerals are present in a flotation cell they will be carried mechanically into the concentrate. A part of the answer to the decreased specific surface of the concentrate would appear to be its usual flocculated condition, yet this should not entirely account for the large spreads reported. The possibility occurs that the nitrogen adsorption isotherms for clean mineral and collector-coated mineral are different. If that were true, and if the coated mineral surface exhibited decreased adsorptive powers, the discrepancy might vanish. In discussing the disposition of collector ions at mineral surfaces, the authors adopt the more consistent viewpoint that there exists some agreement between the ions of the substrate and those of the superstrate. In the case of xanthate ions on galena, a possible arrangement is shown in Fig. 2. This arrangement shows every xanthate ion being shared by two lead ions, whereas the chemical composition calls for two xanthate ions for each lead ion (p. g). This whole discussion is misleading. In the first place, it is known that xanthate ions are not abstracted by unoxidized galena, hence Fig. 2 should show as the substrate not Pbs but PbS„ Om. It would be equally erroneous to use the lattice arrangement of PGSO4, since the surface properties of xanthate-conditioned anglesite differ from those of xanthated galena. It is highly probable that the state of the galena surface exploited in its flotation is ephemeral, since weathered galena is only poorly, if at all, collected by xanthate. Just how a substrate of oxidized galena is to be pictured depends upon one's conception of the transformation from galena to anglesite. This writer is inclined to the following sequence of events. Surface sulphide ions undergo progressive oxidation. As more oxygen is taken up by the sulphide ions they become displaced from their equilibrium positions in the galena lattice, thus accommodating for the larger volume of the S„ Om ions. Concomittant with this change the forces acting on the lead ions

Jan 1, 1946

By Enrique Hauser

FiRE-damp is a mixture of methane with other inert gases or combustible gases. The inert gases in question are carbonic acid, water vapor, nitrogen, etc. The combustible gases are hydrogen, ethane, etc. The study of the properties of fire-damp, therefore, becomes a study of the properties of methane and the influence on its properties of the different gases we have mentioned. Characteristic Properties of Methane 1. Respirability.—Methane being a paraffin is characterized by its weak chemical affinities. Prom the physiological point of view one could substitute it for nitrogen of the air at least momentarily, without experiencing any difficulty in breathing the mixture consisting of 21 per cent. 02 + 79 per cent. CHI. I have tried this on myself, making the gas exhaled from the lungs burn subsequently in a Bunsen burner.' From the chemical point of view, this weak affinity permits the gas to be burned in certain circumstances with hydrogen and oxide of carbon in an oxygenated mixture, with the result that the last two gases achieve only a fractional combustion. This practice has been utilized with success in the methods of analysis which I have perfected and which I describe later in this paper. 2. Retardation of Flashing Point.—A characteristic property of methane is its retardation of flashing point, noted by Davy in 1816 and studied by Mallard and Le Chatelier in 1883.2 Taffanel and Le Floch have recently confirmed these results.8 Let us recall the nature of this retardation: When a mixture of combustible gases with air or with oxygen is

Jan 1, 1916

By A. N. Winchell

In connection with law suits between mining companies at Bingham, Utah, a few years ago, the writer made petrographic studies of more than 1400 rock and mineral samples in thin sections, and also careful studies of their field relations. In petrographic studies, even when an area is studied intensively, attention is commonly centered very largely on the unusual features of special interest, so that the relative abundance of rock types (or minerals or textures) can only be determined by a study of map areas outlined largely by field methods, and cannot be based directly on microscopic work. It is very uncommon, and usually impossible, to take samples at regular short intervals along and across formations. It is precisely because such methods were used at Ringham that the work presents a rare opportunity for determining, on a microscopic basis, the relative abundance of rock types and the continuity of gradations between rock types. At the same time, a study was made of the alteration of sediments under the influence of igneous intrusions, with results that are believed to be of interest and importance. • Sandstone-limestone Gradation The sedimentary rocks of the Bingham district are chiefly sandstones, with some beds of limestone, all now lying with their strike nearly east and their dip nearly north at an angle of about 30°, near the surface. The limestone beds are remarkably irregular in thickness in some places, but usually change very slowly in composition along the strike. However, the most interesting results are obtained from a study of a section across the beds at right angles to the strike. In some places, such sections show the usual alternation of pure sandstone with nearly pure limestone, in the simple manner assumed in most geological discussions.

Jan 1, 1924

By Fred A. Anderson, George B. Wallace, Edward J. Slebir

Auburn Dam will be a thin, double-curvature concrete arch dam about 685 ft high. With a crest length of about 4000 ft, it will be the world's longest single-arch dam. The site is located on the North Fork of the American River about 40 miles northeast of Sacramento, Calif. Construction is scheduled to get under way in 1970. In planning for the design and construction of Auburn Dam (see artist's conception), the foundation material, with its various discontinuities, is being investigated and the structural characteristics of the rock mass evaluated. The investigation and testing programs will aid in defining the pertinent geologic features and their individual and cumulative influence on the foundation. The work includes geologic surface mapping, surface trenching, core drilling, geophysics, tunneling, excavating shafts and raises, performing in-situ tests, and conducting laboratory tests on core and block samples. Competent amphibolite is the predominant material in the foundation, but significant bodies of chloritic, talcose, and metasedimentary rocks, a strongly developed jointing pattern, faults, and shear zones also affect the deformability of the rock mass. A comprehensive rock mechanics program, closely coordinated with geologic investigations as well as the engineering studies, therefore is required The rock mechanics work is a combination of many analytical studies and experimental investigations. The experimental work includes laboratory tests on core samples from holes drilled for geological studies of the entire foundation and in-situ tests performed in selected areas. The laboratory testing program evaluates the general properties of all important rock types and aids in correlating many of the key structural features encountered within the foundation. To derive maximum benefit from the field tests, they are conducted in materials which represent a

Jan 1, 1970

In 1970, the federal Clean Air Act was passed, promulgating limits on the emissions of sulfur dioxide (SO2) from large stationary sources that would affect local air quality. The brunt of this regulation was felt by the electric utility industry, especially those units generating electricity with coal-fired boilers. The law hastened development of a new industry, flue gas desulfurization (FGD), which is composed of three major segments: the electric utility, the FGD equipment suppliers (the scrubbing modules), and the scrubbing chemical suppliers. Dravo's experience suggested the equipment end of the business, but market analysis recommended investigating the chemical processes involved in the removal of the SO2 gas. This resulted in the formation of Dravo Lime Co. to manufacture and market reagents to the FGD industry. This paper will briefly describe the Thiosorbic lime scrubbing process and review Dravo's innovative mine and calcining facility.

Jan 1, 1982

By Ossi V. I. Hintikka, Andrew Balint

Sorting tests on limestone at the Lohjan Kalkkitehdas Oy Ojamo mine, Finland, are described. The tests, conducted to evaluate a Sortex 811MW optical separator, were successful, and upon completion, the sorting machine was put into production. Optical separation characteristics of the limestone, used for cement manufacturing, are described. Problems of winter operation are discussed. Operating costs are given.

Jan 1, 1972

By R. H. Jacoby, V. J. Berry

Future depletion performance and ultimate oil recovery from reservoirs producing under volumetric control are often predicted with the aid of a material balance equation. When the reservoir fluid is very volatile, however, certain assumptions implicit in the use of the conventional methods are no longer valid. This is became laboratory differential vaporization test procedures do not adequately represent the reservoir depletion process and the performance of surface separation facilities. In such cases recovery of stock tank oil per unit of pressure decline can be predicted only from a detailed knowledge of the separator conditions and the over-all composition of the fluid entering the wellbore at each stage of depletion. Surface recovery is not simply related to the total quantity of liquid flowing into the well under reservoir conditions. In order to improve predictions for reservoirs which produce volatile oils, a step wise method of calculation has been developed. This method uses relative permeability data and multicomponent flash calculations to predict oil and gas production as a function of reservoir pressure. Calculations are presented for a reservoir containing a volatile crude oil, and predicted tank oil recovery by primary depletion is more than twice that predicted by conventional methods which are known to be adequate for ordinary black crude oils. Calculated maximum produced gas-oil ratio is less than one-fourth of the conventional prediction. Wellstream compositions have also been used to determine variation in stock tank oil composition and liquid content of the separator gas. This information is of particular importance for crude stabilization calculations and for design of gasoline plant facilities to recover LPG and natural gasoline. INTRODUCTION The estimation of oil reserves and the prediction of future recovery performance of petroleum reservoirs is a frequent task of the petroleum engineer. If the reservoir produces under volumetric control, performance calculations for primary depletion are made by combining oil and gas material balances with the gas-oil flow characteristics of the reservoir rock. For black oil reservoirs, the Schilthuis1 type material balance is commonly employed. For gas or gas-condensate reservoirs, where only one phase is flowing under bottom-hole conditions, a more simplified material balance is used. In the period in which these material balance methods were conceived and put into practice, it was common to classify reservoirs according to the type of fluid produced as (1) black oil reservoirs, or (2) gas or gas-condensate reservoirs. Recently, however, deeper drilling and more extensive studies of reservoir fluid properties have led to the recognition of reservoir fluids with phase characteristics between those of ordinary black oils, and gases or gas-condensate fluids. These intermediate fluids contain relatively large amounts of the hydrocarbons ethane through decane and are found in deep, high temperature (250°F) reservoirs. Such fluids are often referred to as high shrinkage crudes or "volatile oils." They are usually characterized by tank oil gravities above 45° API. high solution gas/oil ratios,

Jan 1, 1958

By M. C. Flemings, P. J. Ahearn

Dendvite morphology of unidirectionally solidified Sn-12 pct Bi alloy was determined with the aid of X-ray and macroetch techniques. Columnar growth direction (growth direction of primary arms) in this alloy is [110]; secondary arms grow in the [lii], [111), and [112] directions. Interstices between [112] dendrite arms fill in during early stages of solidification so that well-defined (110) planes are seen in the final structure (parallel to the heat-flozo direction). Similarly, interslices betweex the [111] secondary arrlls fill in to form (112) planes, and interstices between [1111 ] arms fill in to form (112) planes. DENDRITE morphology in alloys is conveniently studied in unidirectionally solidified castings. In this type of solidification, heat is extracted from a single chill surface of the casting while other surfaces are insulated. Solidification progresses from the chill and results in cast grains that are columnar with the long axis of the grain perpendicular to the chill. Dendrite morphology is conveniently studied by examination of etched surfaces parallel and perpendicular to the chill, as previously described.'" Experimental studies on the growth direction for tin are in general agreement. The major growth direction is [110]:-' although this is altered somewhat by supercooling. In one study, tin dendrites pulled from a supercooled melt had a growth orientation 12 deg away from the [110] direction toward the [002] direction.' This orientation could be changed back to the [110] or close to the [110] direction by changing the tempera- ture gradient in the melt. In a study using autoradio-graphic techniques, (111) directions were shown to be directions of preferred growth in addition to the [110) direction.7 PROCEDURE The samples employed in this study were cut from 12 pct Bi-88 pct Sn castings, 1.5 in. in diam and 3.5 in. tall. The casting procedure consisted of heating the charge to 390°C and then pouring the molten alloy directly into a gypsum sleeve mounted on a massive copper chill. Specimens were cut from the ingot, mounted, polished, and etched with Taffs reagent [FeC13 .6H2O, 2 g; HC1, 5 cu cm;H20, 30 cu cm; CzHaOH (95 pct), 60 cu cm].' The dendritic pattern was clearly visible after etching. Photomicrographs at about 8 and 35 times were taken on surfaces parallel and perpendicular to the chill. Laue back-reflection patterns were obtained from three different columnar grains in a singIe polished face 2 in. from the chill. The cut face was polished and positioned in the beam of a Laue camera, so that diffraction occurred from a single dendritic grain. The resulting diffraction pattern was interpreted to determine crystal log raphic orientation in relation to the heat-flow direction and in relation to microstruc-ture of the given grain. RESULTS Fig. 1 shows a horizontal and vertical section of the columnar structure, at low magnification. Light regions are rich in tin, and darker regions tin-poor; the primary phase is tin-rich a phase. The two sections shown were taken orthogonally from the same metallographic specimen. It is readily seen from Fig. 1 that the dendrites have

Jan 1, 1968

By S. Fukushima, E. Kimura

In the Mitsubishi beneficiation process of ilmenite, chlorine is regenerated in the dechlorination furnace where the gases produced from a selective chlorination of ilmenite are directly introduced. The present paper describes a reaction mechanism and mixing characteristics of the reactant gases for dechlorination of ferric chloride with oxygen. A furnace of a small diameter where the reactant gases passed through in the state of nearly plug flow was used for determination of the effects of temperature and of partial pressures of ferric chloride and oxygen on the rate of the reaction. The experimental data of the reaction rate were applied to various models for calculations of the rate equations and the most suitable reaction model was determined. The results of the experiments also showed that effects of gas mixing onto the reaction rate could not be ignored, so that experiments of gas mixing was carried out. Gas flow patterns and scale effects were observed with use of transparent model furnaces of different sizes.

Jan 1, 1976

By D. L. Martin

The study of cobalt-platinum alloys has been of interest since they represent a class of permanent-magnet material in which the disorder-to-order transformation plays a controlling role. The magnetic properties of alloys in the range 40 to 60 at. pct have been found to be greatly influenced by composition and heat-treatment. The peak properties of 4700 coercive force and 9,000,000 gauss-oersteds energy product were obtained by controlled cooling and aging. These high values combined with ductility and machin-ability give the alloys useful characteristics although their high cost limits their application. THE cobalt-platinum alloys have been of interest in the study of permanent-magnet materials ever since the discovery by Jellinghaus that they had unusually high coerceive-force values.' The high coercive force was associated by Jellinghaus with the disorder-order reaction which occurred in these alloys. This was later verified by Gebhardt and Koster in a detailed study.2 An investigation of the structure, mechanism, and kinetics of the disorder-order transformation and resulting property changes in cobalt-platinum alloys has been in progress for some years. Certain phases of this study related to equilibrium rela- tions, and to the mechanism and kinetics of the ordering reaction have been published previously.3-5 In this paper, the results of the processing and heat-treatment studies on 40 to 60 at. pct CO alloys are presented. The magnetic properties have been found to be influenced greatly by the composition, by the cooling rate from the disordering treatment, and the final ordering time and temperature. Coercive force values, Hc, of 4700 oersteds and energy values, (BH)m, approaching 9,000,000 gauss-oersteds have been obtained by controlled cooling and ordering. PROCESSING OF THE ALLOYS The composition range of interest for permanent-magnet properties centers around the equiatomic composition Copt. In this region the alloys are dis-

Jan 1, 1959