Search Documents

By C. E. Shoenfelt

Jan 1, 1942

By J. D. Verhoeven

In the past 15 years a considerable amount of experimental and theoretical work has been done concerning the onset of convection in liquids as a result of interm1 density gradients. This work, which has been doue in many different fields, is reviewed here and extended slightly to give a rrlore quantitative understanding to the probletrz of conzection in liquid metal dlffusion experinletzts. In liquid metal systems the capillary reservoir technique is currently used, almost exclusively, to measure diffusion coefficients. In this technique it is necessary that the liquid be stagnant in order to avoid mixing by means of convection currents. Convective mixing may result from: 1) convection produced as a result of the initial immersion of the capillary; 2) convection produced in the region of the capillary mouth as the result of the stirring frequency used to avoid solute buildup in the reservoir near the capillary mouth; 3) convection produced during solidification as a result of the volume change; and 4) convection produced as a result of local density differences within the liquid in the capillary. The first three types of convection have been discussed elsewhere1-a and are only mentioned for completeness here. This work is concerned only with the fourth type of convection. Local density differences will arise within the liquid as a result of either a temperature gradient or a concentration gradient. It is usually, but not always, recognized by those employing the capillary reservoir technique that the top of the capillary should be kept slightly hotter than the bottom and that the light element should be made to migrate downward in order to avoid convection. In the past 15 years a considerable amount of work, both theoretical and experimental, has been done in a number of different fields which bear on this problem. This work is reviewed here and extended slightly in an effort to give a more quantitative understanding of the convective motion produced in vertical capillaries by local density differences. The Stokes-Navier equations for an incompressible fluid of constant viscosity in a gravitational field may be written as: %L + (v?)v = - ?£ + Wv - g£ [1] where F is the velocity, t the time, P the pressure, p the density, v the kinematic viscosity, g the gravitational acceleration, and k a unit vector in the vertical direction. A successful diffusion experiment requires the liquid to be motionless, and under this condition Eq. [I] becomes: where a is the thermal expansion coefficient [a =-(l/po)(dp/d)], a' is a solute expansion coefficient [a' = -(l/po)(dp/d)], and the solute is taken as that component which makes a' a positive number. Combining with Eq. [3] the following restriction is obtained: Since there is no fixed relation between VT and VC in a binary diffusion experiment, Eq. [5] shows that the condition of fluid motionlessness requires both the temperature gradient and the concentration gradient to be vertically directed. Given this condition of a density gradient in the vertical direction only, it is obvious that, as this vertical density gradient increases from negative to positive values, the motionless liquid will eventually become unstable and convective movement will begin. The classical treatment of this type of instability problem was given by aleih' in 1916 for the case of a thin fluid film of infinite horizontal extent; and a very comprehensive text has recently been written on the subject by handrasekhar.' It is found that convective motion does not begin until a dimensionless number involving the density gradient exceeds a certain critical value. This dimensionless number is generally referred to as the Rayleigh number, R, and it is equal to the product of the Prandtl and Grashof numbers. For the sake of clarity a distinction will be made between two types of free convection produced by internal density gradients. In the first case a density gradient is present in the vertical direction only, and, since the convection begins only after a critical gradient is attained, this case will be called threshold convection. In the second case a horizontal density gradient is present and in this case a finite convection velocity is produced by a finite density gradient so that it will be termed thresholdless convection. Some experimentalists have performed diffusion experiments using capillaries which were placed in a horizontal or inclined position in order to avoid convection. These positions do put the small capillary dimension in the vertical direction and, consequently, they would be less prone to threshold convection than the vertical position. However, if the diffusion process produced a density variation, as it usually does, it would not be theoretically possible to avoid thresh-

Jan 1, 1969

By D. W. Peaceman

In previous papers by this author on numerical calculations of multidimensional miscible displacement, some simplifying assumptions were made in writing the dispersion term of the differential equation. It was assumed that the flow vectors were essentially parallel to the x-axis. However, in most multidimensional miscible displacements, the flow vectors are not so simply oriented with respect to the coordinate axes. This paper derives the correct dispersion term /or the more general case; gives a difference approximation /or the dispersion tern; and derives the stability criterion for the corresponding explicit difference eguation.

Jan 1, 1967

By H. I. Smith

THE technical and safety press have devoted much space in support of or in opposition to the use of booster and auxiliary fans in coal mines. The Mine Safety Board of the U. S. Bureau of Mines has given the matter consideration, and the Mine Ventilation Committee of the A. I. M. E. is now seeking a discussion of the merits and demerits of such fans to guide it in formulating recommendations. In this paper, I will set up some principles on which I believe most engineers will agree and from which we may work toward a decision, though as to what that decision shall be there may be a difference in opinion. Before stating the points on which I believe. there is accord, I will distinguish between booster and auxiliary fans.

Jan 1, 1927

By F. W. Lee

A GREAT CURTAILMENT of field activities among the geophysicists occurred last year, especially in prospecting for the common metals. In gold, however, an "outstanding achievement . . . was made by the engineers of Consolidated Goldfields. Here the suboutcrop of the Main Reef Series was traced from Middelvlei through properties of the westward area, a distance of from 30 to 40 miles. Here Drs. Reineche and Krahman prospected with the aid of a sensitive magnetometer and established the singularities of the various beds which heretofore had not been sufficiently appreciated. Several underlying shale beds were used to determine this suboutcrop under the dolomite. This area promises to be the equivalent of one-half the size of the present gold fields and to rank in value with the Far East Rand." The present temperature compensated magnetometers permit accurate field observations to less than 5 gammas. Since magnetic anomalies may have their origin due to a change of elevation as well as to the outcropping of a bed of another magnetically different material, intimate geological knowledge is of great assistance in the interpretation of these measurements. To what extent magnetic measurements reflect the basement when the material is homogeneous, consisting primarily of red granite, was determined by members of the Bureau of Mines and described by Dr. J. H. Swartz. Because of the diverse causes of magnetic anomalies, some of which were discussed and correlated by Stratton and Joyce upon known conditions, magnetometer measurements are often difficult to interpret.

Jan 1, 1933

By Cadwallader Evans

THE American Institute of Mining Engineers was organized in the anthracite region of Pennsylvania by men who were primarily interested in anthracite. Its first meeting, at Wilkes-Barre, Pa., in the Northern Anthracite field, on May 16, 1871, resulted from a call sent out by three outstanding men of the anthracite .industry: Eckley B. Coxe, R. P. Rothwell, and Martin Coryell. The best known of these was Eckley B. Coxe, who was the manager of large hold¬ings operated by him and his family,. and who is remembered as the inventor of a special grate for burning very fine anthracite, known as the Coxe traveling grate, which is still very widely used. R. P. Rothwell was a well-known consulting engineer of the region, as was Martin Coryell, who was associated with another well-known anthracite family, the Pardees. There is no record of the discussions that resulted in this initial meeting, but it is safe to assume that the formation of the Institute was largely influenced, through appreciation by the founders, of the necessity for a free exchange of information covering the whole of the mining industry. One of the rules adopted at the first meeting was:

Jan 1, 1947

By A. W. Allen

Progress in the art of amalgamation in recent years has been negligible, partly because a copper plate, though it occupies extensive floor space, requires frequent attention and invites theft, is a simple piece of apparatus that gives visible results; partly because the impression prevails that amalgamation is too primitive a process to merit consideration by an up-to-date metallurgist. Both these objections can be overruled. Plates can and will be superseded by more efficient, theft-proof amalgamating units. Improved methods of application other than by settlement or by impact, neither of which is effective for removal of fine gold, will be developed, and the process given wider opportunity. As A. F. Crosse aptly remarked, neglect to utilize amalgamation when free gold can be recovered thus is comparable to the decision of a storekeeper to deal only with credit customers. Usual practice is to follow amalgamation with cyaniding. Rarely is attention paid to the possibility of reversing the order—of extraction of the fine gold first by cyaniding; the coarse, subsequently, by amalgamation. Such a sequence avoids the alleged hazard that amalgamated gold particles may be unacted upon by cyanide, whereas cyanided gold particles are readily amalgamated. Research has indicated, however, that the mercury coating on a gold particle is easily soluble in cyanide solution, probably because such coating is a compound of gold and mercury. Comparative-test results at one plant, of cyaniding a ground concentrate before and after amalgamation, showed total extractions of about 90 and 100 per cent, respectively, indicating high solubility of the mercury-gold particle, if present, or the advantage of preliminary impoverishment before cyaniding, or both. The contention that a loss in residue from an amalgamation-cyanidation plant is occasioned by presence of amalgamated gold that escapes action by solution is not supported by adequate evidence. The function and scope of mercury as an aid to extraction of gold by cyanide is deserving of attention. It is a powerful desulfurizer. To restrict an extractive process to a concentrated product is logical and economical, if preliminary concentration will segregate a high per-

Jan 1, 1935

Jan 1, 1948

By A. E. Harnsberger

IT is obvious that details such as the physical and chemical properties and methods of heat-treating of the materials mentioned must be omitted in a paper on the subject of materials used in oil-refinery pumps1. Only sufficient identification is given to enable the reader to find additional information from already published data. Also, the subject covers many operating conditions, but only the most important services can be discussed here. To the oil refiner, the pumping equipment is of vital interest. Practi-cally every refinery operation, from the charging of crude oil to a dis-tillation unit to the shipping of refined products, involves some form of pumping machinery. Intermediate refining stages involve a great variety of pumping machinery to carry out successfully the aims of the refinery technologist. Temperatures at which oils are handled vary from -50° F. to 900° F. Pressure may vary from subatmospheric to 2000 lb. per, sq. inch. The selection of the proper materials involves a careful consideration of the conditions under which the particular pump must operate. The four most important considerations are temperature, pressure, corrosion, and abrasion or wear. Consideration of temperature may be divided into three parts: (1) extremely low temperatures of the order of -50° F.; (2) temperatures at atmospheric or slightly above; (3) temperatures from 200° to 900° F. Pressures fall into two groups: (1) pressures reached by ordinary trade pumps of the order of 200 lb. per sq. in., (2) extreme pressure conditions involving pressures as high as 2000 lb. Noncorrosive and corrosive oils can be treated differently. Under the latter falls corrosion in the presence of water, which will occur up to 250° F. The second type of corrosion occurs in high-temperature pump-ing equipment, with temperatures from 450° to 900° F., largely caused by sulfur compounds. There are also other corrosive conditions met with

Jan 1, 1935

By Charles E. Lundin

The character of the Er-D system was established by determining pressure-temperature-composition relationships. A Sieuerts&apos; apparatus was employed to make measurements in the temperature range, 473" to 1223"K, the composition range of erbium to ErD3, and the pressure range of 10~s to 760 Torr. The system is characterized by three homogeneous phase regions: the nzetal-rich, the dideuteride, and the trideuteride phases. These phases and their solubility boundaries were deduced from the family of isotherms of the system zchich relate the pressure-temperature-composition variables. The equilibrium plateau decomposition relationships in the two-phase regions were determined from can&apos;t Hoff plots to be: The differential heats of reaction in these two regions are AH = - 53.0 * 0.2 and -20.0 *0.1 kcal per mole of D2, respecticely. The differential entropies of reaction are AS = - 36.3 * 0.2 and - 31.0 * 0.2 cal per mole D2. deg, respectively. Relative partial molal and intepal thermodynamic quantities were calculated from the pure metal to the dideuteride phase. The study of the Er-D system was undertaken as a logical complement to an earlier study of the Er-H system.&apos; The primary interest was to compare the characteristics of the two systems and relate the difference to the isotopic effect. Studies of rare earth-deuterium systems by other investigators have been very limited in number and scope. Furthermore, there is even less information available wherein an investigator has systematically compared a binary rare earth-hydrogen system with the corresponding rare earth-deuterium system. The available information consists primarily of dissociation pressure measurements in the plateau pressure region of a few rare earths. Warf and Korst&apos; determined dissociation pressure relationships for the La- and Ce-D systems in the plateau region and several isotherms for each system in the dideuteride region. They compared these data with those of the corresponding hydrided systems. The study of these systems as a whole was very cursory and did not give sufficient data for a thorough comparison of the effect of the hydrogen vs the deuterium in the respective rare earths. The heat capacities and related thermodynamic functions of the intermediate phases, YH, and YD2, were determined by Flotow, Osborne, and Otto,~ and the investigation was again repeated for YH3 and YD3 by Flotow, Osborne, Otto, and Abraham.4 This investigation studied only these specific phases. Jones, Southall, and Goodhead5 surveyed the hydrides and deu-terides of a series of rare earths for thermal stability including erbium. They experimentally determined isotherms of selected hydrides and plateau dissociation pressures for deuterides. These data allowed comparison of the enthalpy and entropies of formation of the dihydrides and dideuterides. To date, no one rare earth has been selected to thoroughly establish the complete pressure-temperature-composition (PTC) relationships of binary solute additions of hydrogen and deuterium, respectively. The objective in this investigation was to provide the first comparison of a complete family of isotherms of a rare earth-deuterium system with those of a rare earth-hydrogen system. This would allow one to determine what differences exist, if any, in the various phase boundaries and the thermodynamic relationships in various regions of the systems. I) EXPERIMENTAL PROCEDURE A Sieverts&apos; apparatus was employed to conduct the experimental measurements. Briefly, it consisted of a source of pure deuterium, a precision gas-measuring buret, a heated reaction chamber, a mercury manometer, and two McLeod gages (a CVC, GMl00A and a CVC, GM110). Pure deuterium was obtained by passing deuterium through a heated Pd-Ag thimble. A 100-ml precision gas buret graduated to 0.1-ml divisions was used to measure and admit deuterium to the reaction chamber. The reaction unit consisted of a quartz tube surrounded by a nichrome-wound furnace. The furnace temperature was controlled by a recorder-controller to . An independent measurement of the sample temperature in the quartz tube was made by means of a chromel-alumel thermocouple situated outside, but adjacent to, the quartz tube near the specimen. Pressure in the manometer range was measured to k0.5 Torr and in the McLeod range (10~4 to 10 Torr) to *3 pct. The deuterium compositions in erbium were calculated in terms of deuterium-to-erbium atomic ratio. These compositions were estimated to be *0.01 D/Er ratio. The erbium metal was obtained from the Lunex Co. in the form of sponge. The metal was nuclear grade with a purity of 99.9+ pct. The oxygen content was reported to be 340 ppm and the nitrogen not detectable. Metallographically the structure was almost free of second phase (<i vol pct). A quantity of sponge was arc-melted for use as charge material. The solid material was compared with the sponge in the PTC relationships. They were found to be identical. Therefore, sponge material was used henceforth, so that equilibrium could be attained more rapidly. The specimen size was about 0.2 gr for each loading of the reaction chamber. The procedure employed to obtain the PTC data was to develop experimentally a family of isothermal curves of composition vs pressure. First, a specimen

Jan 1, 1969

By Carl F. Dietz

(New York Meeting, February, 1912.) THE problem of drying ores is one that most mill-engineers are sooner or later called upon to meet, and it may be timely to point out sortie of the difficulties resulting from such operations from purely a metallurgical and economic stand-point. We mean, in the following pages, to discuss primarily the effect of such operations on. the ore itself, without particular reference to the mechanical or cost features of the subject; That an appreciable tonnage of the ore fed to the usual form of drier, either rotary or stack, is lost, is fairly well appreciated, but we believe that only a few mill-managers know just. what their drier-losses amount to, and we have found that in most cases they console themselves with the fact that the drier-smoke is not very much discolored, and it is generally believed that the draft is not sufficient to carry away more than a. negligible percentage of the values. The drying of ores is becoming an important factor. since the more general application of magnetic, static, and dry-table treatment. Its importance in the field of metallurgical operations warrants a close examination into its effects. This subject has been repeatedly brought hone to us, and while the drier-losses, in every case examined, have considerably exceeded even the most generous estimate, an attempt at a recovery of these values is rarely made. We have found that the losses resulting from drying-operations can be effectively recovered, at a low cost, and believe that the publication of the results of a number of investigations along these lines will be of interest and benefit to the profession at large. To dry an ore quickly and effectively, it must be brought into actual contact with hot gases or air. The rapid drying is effected by the fact that the hotter the gas the hungrier it is

Jul 1, 1912

By Russell Spry, Paul Schutz

The property of Pioneer Gold Mines of B.C. Limited is in the Lillooet mining district of British Columbia. It is on Cadwalleder Creek, 54 miles distant by motor road from Shalalth, a station on the Pacific Great Eastern Railway. Interests identified with the present company installed a small amalgamation plant on the property in 1924, consisting of a jaw crusher, Bryan mill and amalgamation plates, in which 75 per cent extraction was made on mill feed averaging 1.0 oz. gold per ton, the tailing being stacked for future treatment. That plant was operated until 1928, when the present company was formed and a 100-ton continuous counter current decantation cyanide plant was built. A second unit, having a nominal capacity of 200 tons daily, was added in 1932 and put into operation during September of that year. When handling ore comparatively free from slow-settling material, the combined capacity of the two units is 400 tons, the original plant now handling about 140 tons maximum. Production to date, from Pioneer, has been about $6,500,000, the present monthly production being better than $250,000 from about 370 tons ore daily, the recovery being 97 per cent. During the fiscal year ending March 31, 1934, a total of 112,936 tons ore and old amalgamation tailing was milled, the mill feed averaging 0.7670 oz. gold and the recovery amounting to 0.7422 oz. gold per ton, or 96.77 per cent. Milling costs, including refining and mint charges, during this period, amounted to $1.45 per ton of ore. Since the building of the first unit of the cyanide plant in 1928, direct cyanidation has been employed, no attempt being made to remove coarse gold from the circuit, other than that cleaned up from the grinding mills during relining and from the classifiers, as occasions permit. In the hope of still further increasing recovery, researches are going forward at this time with the view to removing some of the sulfides after primary grinding, the expectation being that selective treatment of this more refractory portion of the ore may hold economic possibilities.

Jan 1, 1935

By J. A. Herbst, R. Mackelprang, J. D. Miller

Droplet size distributions were determined by stabilizing in gelatin and measurement of the distributions by means of computerized image analysis Several variables that affect droplet sizes were studied and the resulting size distributions were modeled via a population balance equation Key parameters in the model were related to the physical properties and operating conditions of the systems examined using a multiple linear approach

Jan 1, 1981

By S. W. Ihle, L. J. Warren

A sample of garnet from the scheelite ore body on King Island, Tasmania, Australia, was upgraded and ground to produce an ultrafine portion suitable for micro-electrophoresis. X-ray and chemical analysis identified the garnet as andradite with some admixed grossular. At neutral pH the garnet particles were negatively charged, their zeta potential becoming rapidly more negative with increasing pH. An iso-electric point was found at pH 3.5. The effects on the zeta-potential of various electrolytes, hydrolyzable metal ions, and flotation collectors were also studied.

Jan 1, 1976

[NORTH AMERICA UNITED STATES ALABAMA Birmingham CORD, Richard H DISMUKES, Edward B Citronelle PERRIN, Huey P Fairfield PAGEL, Herbert Ervin Huntsville ENG, Harvard KELLEY, Dean W WAGGONER, J B Mobile HORNER, William L PETROUTSON, Peter C Montgomery GAMBLE, Halbert R Redstone RAWLINGS, William E Tuscaloosa MASON, William L University CUDWORTH, James R JONES, Walter B]

Jan 1, 1961

By C. Dinis da Gama

In order to reduce the complexity of mechanisms influencing rock. fragmentation by blasting a simulation approach is proposed, using the capabilities of microcomputer interactive graphics. Situations involving cratering end bench blasting are simulated, and both jointed and intact rocks can be subjected to explosive action, taking into consideration its breakage mechanisms. Size analysis curves relating rock distribution before and after the blasts are determined and compared with field data.

Jan 1, 1984

By Kenneth C. Vincent, A. M. Gaudin

In a study1 of the action of amyl xan-thate on chalcocite in water suspension, it was found that if the xanthate is added in relatively large quantity the xanthate group can be accounted for in three forms: (1) as xanthate ion remaining in water, (2) as benzene-soluble cuprous xanthate on the chalcocite, (3) as a benzene-insoluble coating on the chalcocite. Reduction in the amount of xanthate added leads to disappearance of form I then of form 2. With minute quantities of added xanthate, substantially all the reagent is of the "unleachable" kind. Yet this unleach-able xanthate can be dissolved by pyridine to form a soluble cuprous xanthate complex, and it is sufficient in effectiveness to make chalcocite flotable even if insufficient in quantity to form a complete mono-molecular film on the mineral. In that study it was also found that chalcocite abstracts cuprous xanthate from benzene so1ution, in what may (or may not) be a case of molecular adsorption. It seemed desirable, therefore, to study further the "unleachable" xanthate on the chalcocite, and particularly to ascertain whether it is formed as a result of the benzene leach or is actually formed during the conditioning of chalcocite in aqueous xanthate solution. A &apos;splendid tool to make such studies has recently been perfected; that is, the use of radioactive spies or tracer atoms. With this tool, it was thought possible to answer the problem stated above, but, unfortunately, this did not prove to be true. Answer to the flotation question was clouded by the existence of rapid and selective diffusion of copper atoms in the solid mineral—a phenomenon that was totally unexpected yet remains interesting and perhaps important. Method of Radioactive Spies The method of radioactive spies is discussed in many places. Two convenient references are the article by Evans2 and the book by pollard and Davidson.3 The method was first developed by van Hevesy and paneth in 1013, when only natural radioactive isotopes were available. These isotopes are few in number, and so the method remained limited in scope. Recently the synthesis of over 350 active isotopes of all the known stable chemical elements4 has opened widely expanded possibilities for the method, A fundamental tenet of the method is that a radioactive atom and a nonradio-active atom are exactly alike until disintegration of the radioactive atom. Then, by its sudden death, the spy reveals its location. The relative abundance of spies at various locations makes it possible to ascertain the relative abundance of the corresponding nonradioactive atoms at the same times and locations. A second fundamental tenet of the method of radioactive tracers is that the radioactivity lies in the nucleus of the atom: transfer of radioactivity from one

Jan 1, 1947

By Kenneth C. Vincent, A. M. Gaudin

In a study1 of the action of amyl xan-thate on chalcocite in water suspension, it was found that if the xanthate is added in relatively large quantity the xanthate group can be accounted for in three forms: (1) as xanthate ion remaining in water, (2) as benzene-soluble cuprous xanthate on the chalcocite, (3) as a benzene-insoluble coating on the chalcocite. Reduction in the amount of xanthate added leads to disappearance of form I then of form 2. With minute quantities of added xanthate, substantially all the reagent is of the "unleachable" kind. Yet this unleach-able xanthate can be dissolved by pyridine to form a soluble cuprous xanthate complex, and it is sufficient in effectiveness to make chalcocite flotable even if insufficient in quantity to form a complete mono-molecular film on the mineral. In that study it was also found that chalcocite abstracts cuprous xanthate from benzene so1ution, in what may (or may not) be a case of molecular adsorption. It seemed desirable, therefore, to study further the "unleachable" xanthate on the chalcocite, and particularly to ascertain whether it is formed as a result of the benzene leach or is actually formed during the conditioning of chalcocite in aqueous xanthate solution. A &apos;splendid tool to make such studies has recently been perfected; that is, the use of radioactive spies or tracer atoms. With this tool, it was thought possible to answer the problem stated above, but, unfortunately, this did not prove to be true. Answer to the flotation question was clouded by the existence of rapid and selective diffusion of copper atoms in the solid mineral—a phenomenon that was totally unexpected yet remains interesting and perhaps important. Method of Radioactive Spies The method of radioactive spies is discussed in many places. Two convenient references are the article by Evans2 and the book by pollard and Davidson.3 The method was first developed by van Hevesy and paneth in 1013, when only natural radioactive isotopes were available. These isotopes are few in number, and so the method remained limited in scope. Recently the synthesis of over 350 active isotopes of all the known stable chemical elements4 has opened widely expanded possibilities for the method, A fundamental tenet of the method is that a radioactive atom and a nonradio-active atom are exactly alike until disintegration of the radioactive atom. Then, by its sudden death, the spy reveals its location. The relative abundance of spies at various locations makes it possible to ascertain the relative abundance of the corresponding nonradioactive atoms at the same times and locations. A second fundamental tenet of the method of radioactive tracers is that the radioactivity lies in the nucleus of the atom: transfer of radioactivity from one

Jan 1, 1947

By Harry W. Brown

This paper presents results of static capillary pressure measprements made both by the restored-state and by the mercury-injection methods, and of dynamic capillary pressure measurements made by the Hassler technique. The results indicate a variation from sample to sample of the factor used to convert capillary pressure obtained by mercury injection to those applicable to a water-gas system. Static capillary pressures measured by the restored-state method were found to be in close agreement with dynamic capillary pressures, indicating that data obtained from static measurements may be utilized with confidenre in the solution of dynamic problems of fluid flow. Experimental data are presented on the use of "J-curves" for the correlation of capillary pressure-saturation relations for a number of cores from a particular geologic formation. It is shown that the correlation was improved in some cases by reqtricting it to rertain lithologic classifications. INTRODUCTION The Meaning and Importance of Capillary Pressure The coexistence of two or more immiscible fluids within the voids of a porous medium, such as reservoir rock, gives rise to capillary forces. Because of the interfacial tension existing at the boundary between two immiscible fluids in a pore space, the interface is curved, and there is a pressure difference across the interface. This pressure difference is termed the capillary pressure. The magnitude of the capillary pressure between two immiscible fluids which together fill a porous medium depends upon several factors: the textural properties of the medium, the wettability of the medium, the interfacial tension between the fluids, the respective saturations of the fluids, and the manner in which these saturations are attained. For a given pair of immiscible fluids in a particular sample of reservoir rock, the capillary pressure is a unique function of the fluid saturation, provided that the saturation of the fluid which wets the rock has previously been decreased unidirectionally from an initially complete saturation. Similarly, for a given pair of fluids at a particular saturation which has been achieved by a

Jan 1, 1951

By Harry W. Brown

This paper presents results of static capillary pressure measprements made both by the restored-state and by the mercury-injection methods, and of dynamic capillary pressure measurements made by the Hassler technique. The results indicate a variation from sample to sample of the factor used to convert capillary pressure obtained by mercury injection to those applicable to a water-gas system. Static capillary pressures measured by the restored-state method were found to be in close agreement with dynamic capillary pressures, indicating that data obtained from static measurements may be utilized with confidenre in the solution of dynamic problems of fluid flow. Experimental data are presented on the use of "J-curves" for the correlation of capillary pressure-saturation relations for a number of cores from a particular geologic formation. It is shown that the correlation was improved in some cases by reqtricting it to rertain lithologic classifications. INTRODUCTION The Meaning and Importance of Capillary Pressure The coexistence of two or more immiscible fluids within the voids of a porous medium, such as reservoir rock, gives rise to capillary forces. Because of the interfacial tension existing at the boundary between two immiscible fluids in a pore space, the interface is curved, and there is a pressure difference across the interface. This pressure difference is termed the capillary pressure. The magnitude of the capillary pressure between two immiscible fluids which together fill a porous medium depends upon several factors: the textural properties of the medium, the wettability of the medium, the interfacial tension between the fluids, the respective saturations of the fluids, and the manner in which these saturations are attained. For a given pair of immiscible fluids in a particular sample of reservoir rock, the capillary pressure is a unique function of the fluid saturation, provided that the saturation of the fluid which wets the rock has previously been decreased unidirectionally from an initially complete saturation. Similarly, for a given pair of fluids at a particular saturation which has been achieved by a

Jan 1, 1951