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By John V. Beall

The forecast of continued growing demand for phosphate, chiefly for fertilizer, has caused a world-wide rush for deposits by a variety of companies many of which have never before mined phosphate rock. The newcomers are diversifying into this growth industry on the strength of certain capabilities. Among these are the availability of investment capital, mining or processing know-how and marketing experience. Product tie-ins have motivated some into the search. Companies with excess sulfuric acid or potential for making it are in this category. This acid is the most commonly used for dissolving phosphate rock to make phosphoric acid. Base metal smelting companies are prime candidates in this field with by-product acid from roasting processes. Producers of "sweet" natural gas, such as those in Louisiana and Texas, have a potential for recovering low cost hydrogen from excess gas production for the manufacture of ammonia, the main source of nitrogen for fertilizer. "Sour" gas producers, such as those in the Canadian fields, are making sulfuric acid that is combined with western U.S. phosphate to make fertilizer materials. The presence of one or two steel companies in the look-see for phosphate deposits is based on by-product ammonia from coke-oven gas.

Jan 10, 1966

By J. C. Karcher

GEOPHYSICAL methods have been more extensively applied to prospecting for oil during 1936 than at any previous time. Their use has been extended to include al- most every oil and gas producing area in the United States. More than ten magnetometer parties, more than nine gravimeter parties, more than five electrical surveying crews, more than fifty torsion balance parties, more than two hundred seismic reflection parties, and several refraction parties were- operating in the United States throughout the year. A tendency has been noted to abandon the use of the pendulum for geophysical prospecting in the oil fields and to increase the use of the

Jan 1, 1937

By T. A. Rickard

The interior of West Australia is an arid table-land, elevated 1400 feet above the sea. This plateau is flanked to the south by the Tertiary limestones which fringe the Great Australian Bight. It is bordered northward by the Carboniferous beds of the Fitzroy river and westward by the granite of the Darling hills, while to the cast this wide area, about 900 miles square, slopes downward imperceptibly into an undulating plain of sand, which stretches with dismal persistence across the boundary of South Australia. The waters of the ocean receded from this tract of land long ago; it is probably the oldest landsurface on the globe, and represents the basal wreck of a much larger continent. Fig. 1 is a map of this region. The Coolgardie and Kalgoorlie gold-fields are situated in the southwestern part of the region. The rock-formation consists of granite penetrated by diorites and andesites. The latter are occasionally associated with tuff's, which have been readily mistaken for sedimentaries. There are no fossil-bearing rocks, such as would afford a datum-line from which to measure the relative geological age of the prevailing formation. On the extreme edges of the mining territory there are, it is true, remnants of sand-rock which are considered identical with the " Desert Sandstone " of Queensland, determined by Daintree to be of Mesozoic age. But even this formation has evidently been laid down so long subsequent to the underlying rocks that it serves merely to emphasize their much greater antiquity. In their characteristics and in their relations to each other, the granite and the diorite of the Coolgardie region appear to me much to resemble the Laurentian granite and the Huronian

Jan 1, 1899

By F. W. Bradley

This chapter on the Alaska Juneau mill is intended to make clear that "choice of methods," or the selection of proper methods, is the first essential step in launching a new enterprise; and to illustrate that when entering into new country where local conditions and physical features are new or strange to an engineer, he should respect the practices already adopted and followed in meeting peculiar conditions in these new countries that may seem strange to a casual visitor. For example, Americans going into Malay Peninsula with their most up-to-date machinery for drilling placer prospect holes found their cost to total about $3 per foot; by adopting native methods, it was found the same work could be done for 50 cents per foot. Also, those not used to frozen road conditions in a country of arctic climate might scrape the snow off such a road and cause unending road troubles into the following spring and summer; while natives understanding local conditions would leave the snow on the road. So in the neighborhood of Juneau, Alaska, where successful gold-milling operations had been going on for

Jan 1, 1932

By Edward P. Barrett

DURING the past few years numerous references have been made in the technical press and Bureau of Mines Bulletin 270 to sponge iron' and so-called "direct metal" processes. The idea has been prevalent that sponge iron and "direct metals" are cheap commodities. In many instances it has been proposed that these processes be used to treat low-grade ores, utilizing low-grade coals as reducing agents. It is questionable whether or not high-grade sponge iron can be made from low-grade materials. Particles contain¬ing iron oxide and gangue become, upon almost complete deoxidation, particles containing metallic' iron and gangue. The possibility of mechanically separating the metallic iron from the gangue in these particles depends . on the physical characteristics of the particular ore under treatment. Some ores, in which the minerals constituting the gangue break free from the iron oxide upon crushing, may be concentrated magnetically after the iron oxides have been reduced to metal. The finely disseminated ores are least amenable to concentration. In general, high-grade sponge iron can only be made from high-grade raw materials. Sponge iron containing small amounts of sulfur can only be made from raw materials containing small amounts of sulfur or by

Jan 1, 1930

By J. E. Brantly

THE oil-producing industry may logically be 'divided into four independent branches: (1) Acquisition of possible productive lands by lease, fee purchase, concession, or otherwise and the perfection of titles thereto. (2) Studies of the geology of the properties, leading to the location of exploratory wells. These involve reconnaissance and detailed surveys and the use of geophysical instruments, where conditions do not permit surface determination. (3) Drilling of exploratory or test holes and, later, exploitation wells. (4) Actual recovery of the oil from the wells by flowing, pumping, or other methods. These four divisions of the industry are unrelated in detail of accomplishment, but they are entirely complementary, one to the other, and must, in any efficient' organization, harmonize in their respective efforts toward the desired ultimate end. The relative order for the first two branches is not necessarily the proper one; in fact one should have knowledge of the favorable possibilities of a given property before it is acquired, and preferably, also, final opinions as to then proper location for an exploratory well, if such is justified in the light of

Jan 1, 1937

By B. Yu, H. M. Lee, R. P. Gardner

Some preliminary results are given on the use of radioactive tracers for implementing the mechanistic approach to flotation. The process studied is an industrial one for the cleaning of sand for the production of glass. The radioactive tracers employed are those produced from intrinsic elements in the sand by neutron irradiation in a nuclear reactor. The results indicate that the technique will be useful for the determination of flotation simulation mechanistic model parameters on operating industrial processes without interruption of their normal operation.

Jan 1, 1980

By Edgar Marburg, William R. Webster

The desirability of bringing about greater uniformity in specifications governing iron and steel is generally recognized, and has found expression within recent years, in the efforts of numerous technical societies in that direction. When the International Association for Testing Materials was organized at Zurich in 1895, a committee was appointed, charged as follows: " On the basis of existing specifications, to seek methods and means for the introduction of international specifications for testing and inspecting iron and steel of all kinds." The American representation on this international committee consisted originally of five, and now of eight members. In view of the magnitude and importance of the subject, the Executive Committee of the American Section of the International Association for Testing Materials, since incorporated as the American Society for Testing Materials, appointed a committee of 34 members, including the American members of the above-named international committee, to frame standard American specifications for iron and steel. This committee reported on specifications for (1) Structural Steel for ridges and Ships; (2) Structural Steel for Buildings; (3) Open-Hearth Boiler-Plate and Rivet-Steel; (4) Steel Rails; (5) Steel Splice-Bars; (6) Steel Axles; (7) Steel Tires; (8) Steel Forgings; (9) Steel Castings ; (10) Wrought-Iron. These specifications were designed to be fairly representa-tive of the best current American practice, and were adopted by letter-ballot of the Society in August, 1901. The leading engineering societies have participated at various times in the discussion of these specifications and have lent valuable assistance through the appointment of special committees on like, or closely related, subjects. The American Society of Civil Engineers discussed the spec-

Jan 1, 1905

By P. Greenfield, C. C. Smith, A. M. Taylor

The Mg-Zr alloy ZA and Mg-Mn alloy AM503(S) are shown to have a markedly improved resistance to creep deformation after suitable heat treatments. This improvement makes them suitable for certain stress-bearing fuel element components in nuclear reactors. The extent of strengthening is described and an explanation of the behavior of both materials is given, based on a combination of strain-aging and grain growth. The increase in operating temperatures of fuel element components in Calder Hall type nuclear reactors has necessitated the development of magnesium base alloys with a very high resistance to creep at temperatures up to 500°C. Such alloys are not required for fuel element cans, which require high-creep ductility rather than strength, but for can supporting and stabilizing components, which are needed to support the imposed loads without deforming more than about 1 pct in times of up to 40,000 hr. The amount and type of alloying addition made to magnesium for these parts is limited by the necessity of keeping the cross-section to thermal neutrons as low as possible. The alloys must also possess a high resistance to oxidation in CO2. Alloys which have been developed for this application include ZA, an alloy of magnesium with 0.5 to 0.7 pct Zr and AM503(S), an alloy of magnesium with 0.5 to 0.75 pct Mn. In the as-extruded condition these alloys are very weak and ductile in creep but it has been found that they can be strengthened to a significant extent by heat treatment. This paper describes the method of developing a high-creep resistance in ZA and AM503(S), the extent of the strengthening produced and discusses the probable mechanisms of strengthening. TEST MATERIALS Specimens were taken from typical casts of ZA and AM503(S) alloys extruded into 2 1/4-in.-diam bars, supplied by Magnesium Elektron Ltd. Typical analyses of the bars were as follows: The as-extruded mean grain diameter was 0.001 to 0.002 in. for the ZA alloy and 0.003 in. for the AM503(S) alloy. EXPERIMENTAL METHODS Extruded bars of ZA alloy, 2 1/4 in. in diameter and 9 in. long, were heat treated in electrical resistance furnaces in an atmosphere of flowing CO2 containing 50 to 300 ppm water, thereby reducing the extent of oxidation compared with that which would have occurred in air. Heat treatments were carried out at 600oc for times of 8, 24, 48, 72, and 96 hr and material was subsequently both furnace cooled and water quenched. In order to measure the effect of time of heat treatment, specimens were creep tested at 400°C and 336 psi for about 1000 hr. Subsequently, the behavior of material heat treated for 96 hr at 600°C and furnace cooled was tested at a variety of stresses from 200° to 500°C. Tests were also conducted at 200o and 400°C on material in the as-extruded condition for comparative purposes. With the AM503(S) alloy, only the effect of heat treatment at 565°C for 4 hr was examined. It has been shown1 that such a heat treatment produces marked strengthening in this alloy. Tests on this material were conducted at a variety of stresses at 200°, 300°, and 400oc with comparative tests on as-extruded material at 200o and 400°C. The creep tests were carried out on machines using dead-weight loading and direct micrometer strain measurements on specimens 5 in. long and 0.357 in. diameter. At temperatures of 400° C and below, the creep tests were conducted in air, but at higher temperatures an atmosphere of CO2 was used. Grain size measurements were made on ZA in the extruded and heat treated states and on each specimen after creep testing. This was done by a line count of a minimum of 20 grains in two or three random fields in the longitudinal and transverse directions. The same method was used for measuring the grain size of as-extruded AM503(S), but the grain size of the heat treated material was so large that this method could not be employed. For heat-treated AM503(S) the large grained characteristics (between 0.1 and 1 in.) were confirmed by the measurement of individual grains. In the case of the ZA alloy, specimens taken from various stages in the program were analysed for hydrogen by a combustion method. Material in various states was also analysed for the soluble and insoluble zirconium content by dissolving in dilute hydrochloric acid. This technique has been useda for the determination of amounts of zirconium present

Jan 1, 1962

By M. S. Seltzer

In a previous paper1 it was shown that activation energies for steady-state creep in lead sulfide single crystals varied with the concentration of electronic defects. For n-type lead-excess crystals, values for the creep activation energy, Qc, decreased from 2.9 to 2.2 ev as the carrier concentration increased from 1017 to 1017 electrons per cu cm, while Q, increased from 1.6 to 2.3 ev for p-type sulfur-excess crystals as the concentration of holes increased from 6 X 1017 to 1018 per cu cm. It was also shown in Ref. 1 that the Q, values could best be correlated with the sum of the self-diffusion activation energies in PbS, i.e., for a given concentration of electrons or holes Q, = QPb + Qs, where Qpb and QS are the activation energies for diffusion of pb210 and s35 in PbS. This result suggests that creep rates are controlled by at least two atomic defects, one for lead migration and one controlling sulfur transport. It would be most desirable to interpret these creep energies in terms of an atomic defect disorder model for lead sulfide. Studies of creep rates as a function of sulfur pressure2 indicate that the defects controlling creep rates are singly ionized lead and sulfur vacancies, VPb and Vs. This hypothesis can be more firmly established by determination of Q, under conditions of constant atomic defect concentration rather than constant electronic defect concentration as has been previously done. Therefore, several measurements have been made of Q, on crystals whose con- centration of lead vacancies or sulfur vacancies has been fixed by equilibration under appropriate sulfur pressure and temperature. It was indicated in Ref. 2 that high-temperature isotherms are available which show how the concentrations of various atomic point defects in PbS vary with composition over the entire homogeneity range for the compound. Two such isotherms are shown in Fig. 1 for 900" and 1000°K. Utilizing these isotherms the concentration of a given defect, say Vbb, may be held constant over a particular temperature range by adjusting the sulfur pressure as the temperature is changed. Thus the concentration of one defect suspected of controlling creep rates may be held constant while other defect concentrations vary. The apparent activation energy for formation of these defects can be obtained from the isotherms giving their concentration as a function of sulfur pressure. Activation energies for creep obtained under conditions of constant defect concentration can then be compared with defect formation energies and certain possible atomic defects can be eliminated as creep-controlling species. We have performed creep experiments as a function of temperature at a stress of 244 g per sq mm under conditions which fixed the lead vacancy concentration, V', at 1016, 3.2 x 1016, and 3.2 x 1017 cm-3, and one were the sulfur vacancy concentration, Vs, was held at lo17 cm-3. The results are presented in Fig. 2 as creep rate, k, vs reciprocal of absolute temperature, 1/T. Specimens 34, 35, and 36 were deformed under constant lead vacancy concentration while specimen

Jan 1, 1969

By Theodore Simons

(Butte Meeting, August, 1913.) DURING the last half century a great amount, of ingenuity and energy has been devoted to the invention of appliances for the recovery of valuable minerals from very fine sands and-slimes. The reason for this is that in almost every, dressing plant the greatest losses of values, considered relatively as well as absolutely, occur in the treatment of slimes. The natural aim of mill operators to minimize these losses has in recent years received another impetus,, from the fact that the gradually diminishing occurrence of high-grade ores makes a more intense recovery of values from existing resources absolutely necessary for profitable operation. The results of such attempts are found in the appearance of a great number of machines and appliances which make it profitable to-day to rework old dumps, containing the tailings of older processes. A constantly growing difficulty of obtaining skilled labor and the increase in wages made it prohibitory to employ those types of machines which required much attention, and in the middle of the nineteenth century the various concentrating tables of the percussion type, which automatically discharge their products, began to take the .place of the intermittent tables, on which, when the bed had reached a certain thickness, operation had to be stopped in order to allow the skimming by hand of the separate layers formed on the table. In the course of. years, two general types of machines evolved for the treatment of fine sands and slimes :- The so-called concentrators and vanners, on the one hand, and the huddles and round tables on . the other.1 For the profitable treatment of the very finest slimes, round tables have as a last resort proved more satisfactory and economical than other machines.

Jan 7, 1913

By J. G. Montgomery

An increased drilling activity was apparent in the shallow sand fields of northwestern Pennsylvania during the year. This drilling, however, was confined to previously outlined productive areas and as new shallow sand pools of interest were discovered. Drilling for Oriskany gas proceeded at about the same rate as in previous years. One new area in Kinzua township, Warren County, was opened up during the year by a producing well, but later this well developed salt water and the productive capacities of the area are very indefinite at the present time. Production from the shallow sand areas remained approximately the same as in 1935. Production from the Oriskany or deep sand areas increased approximately 20 per cent. Two new markets were made available for the Oriskany gas during the closing months of the year by the completion of the Peoples Natural Gas Co. line from the Hebron field to Clarion County, Pa. and Penn York Gas Co. line from the Harrison field to points in northwestern New York State. With the exception of the Kinzua well, the few deep wildcat wells drilled during the year failed to discover new fields in the deep sands. Bradford Oil Field The accompanying data on the Bradford oil field include only the production obtained from the portion of that field that is in the State of Pennsylvania, for it appears probable that Cattaraugus County production, which consists mainly of the New York State portion of the Bradford field, will be included in annual oil production figures for New York State. The Bradford field production for 1936 totaled 14,533,000 bbl., and as it is necessary to estimate New York State production for the Bradford field, the accompanying data includes the production from the Pennsylvania end of the Bradford field of 13,208,000 bbl., which is an increase of approximately 8 per cent over 1935 production.

Jan 1, 1937

By I. Fatt

A recently developed system for measuring electrical resistivity of liquids without use of electrodes offers some interesting possibilities in electric logging technology. The equipment as supplied by the manufacturer is satisfactory for continuous mud logging on a drilling rig or for measuring mud or filtrate resistivity in the laboratory. A simple modification of the commercially available instrument makes it suitable for measuring resistivity of core samples in the laboratory. The continuous measurement of mud resistivity on a drilling rig is a convenient means for detecting mixing of formation water with the drilling mud. Such information is useful to the geologist, the mud engineer and the logging engineer. However, continuous mud resistivity logging by conventional electrode-type resistivity cells is beset with difficulties. The mud, sand and rock chips abrade the electrodes, thereby changing the cell constant and eventually destroying the cell. Also, additives and crude oil in the mud may poison the electrodes by coating them with a nonconductive material. An electrode-type resistivity cell. therefore, may give erroneous readings under certain conditions. Electric logging companies circumvent the electrode poisoning problem by using a four-electrode resistivity cell for measurement of mud resistivity. In this cell, change in electrode area does not change the cell constant. However, the four-electrode cell is difficult to adapt for continuous reading and does not solve completely the problem of electrode abrasion by the sand and cuttings in the mud. The measurement of electric logging parameters on core samples in the laboratory encounters some of the same problems discussed in connection with mud logging. Ideally, the electrical resistivity of a core sample should be measured by placing platinum black electrodes in direct contact with the plane ends of a cylindrical or rectangular sample. Platinum black electrodes however, are much too fragile and easily abraded to be brought in contact with a rock sample. Also, oil or other constituents in the fluid contained in the sample will poison platinum black. In practice, gold-plated brass electrodes, in an AC bridge circuit operating at about 1,000 cps, are used for routine core analysis. For more precise work in research studies, a four-electrode scheme is used.',' Preparation of the samples for the four-electrode method is much too involved for routine core analysis. An apparatus for measuring resistivity of liquids without use of electrodes was described by Guthrie and Boys3 in 1879. They suspended a beaker, containing the electrolyte, by a torsion wire and rotated a set of permanent bar magnets around the vessel. The eddy currents induced in the electrolyte reacted against the rotating magnetic field to develop a torque, which was measured as a deflection of the torsion wire. In 1879 this method could not be made precise or convenient because of the lack of strong permanent magnets. The writer described a very greatly improved apparatus similar to that of Guthrie and Boys, but it was not suitable for continuous measurements or core samples.' Many electrodeless resistivity devices using radio frequency current are described in the literature.5, 6 These generally are suitable only for noting the end-point in a chemical titration. They do not measure resistivity, instead measuring a complex quantity which includes the dielectric constant and the magnetic permeability. The first description of the apparatus to be discussed in this paper was given by Relis.7 Improvements and modifications are described by Fielden,s Gupta and Hills,> and Eichholz and Bettens.10 DESCRIPTION OF APPARATUS The apparatus used in this study is based on the principle that the solution under measurement can form a loop coupling two transformer coils, as shown in Fig. 1. For a fixed AC voltage applied across Coil A, the voltage appearing across Coil B is a function of the resistance of the liquid-filled loop. The details of the voltage generating and measuring circuits are given in Refs. 7, 8, 9 and 10. A block diagram of the equipment is given in Fig. 7. Special features worth mentioning are the operating frequency of 18,000 cps and the automatic temperature compensation which results in the given resistivity readings being automatically correlated to 25°C. The liquid loop supplied by the manufacturer, shown in Figs. 1 and 2, was modified for use in core analysis (Fig. 3). The core sample under test is substituted for a section of the original loop. As shown in Fig. 3, the unit accepts only plastic-mounted cylindrical core specimens. A Hassler-type sleeve easily can be designed for the unit if unmounted cores are to be measured. EXPERIMENTAL PROCEDURE MUD LOGGING A simulated mud line was set up in the laboratory.

By OTTO HERRES

UTAH has enormous deposits of high-grade bituminous coal. The United States Geological Survey estimates that there are 13,130 sq. mi. of land in Utah known to contain workable coal and these extensive fields contain 196,000,000,000 tons of coal. Growth in population and development of industry in the intermountain and Pacific coast regions will in time give Utah a place with the great coal producing states of the country. Even today, faced by adverse conditions in competition with cheap fuel oil from southern California, water-power throughout the western states in general, and comparatively high freight rates to its distant markets, the Utah coal industry is notable in many respects. In recent years, Utah has led the United States both in the percentage of its mines in class 1, mines producing more than 200,000 tons a year, and in average production per man per day, which was 6.01 tons in 1921. In Mineral Resources of the United States, 1921, Part

Jan 1, 1925

By R. V. Smith, M. H. Cullender

Rigorous equations for calculating subsurface pres.tures in flowing and static gas wells, and pressures along horizontal pipelines are presented in this paper. These general equations, based on the mechanical encrgy balance, contain no assumptions regarding temperature and can be used with either straight-line or curved temperature gradients. The friction factors recommended in this report are based on an absolute roughness of 0.0006 in. Flow is always considered to he turbulent. Although these general flow equations are solved by numerical means, the methods are as convenient as many of those used today to calculate pressures in gas wells and pipelines. These numerical methods are illustrated for flowing and static columns of gas in wells and for flow in pipelines. The authors believe that the use of these methods will result in more accurately calculated pressures in gas wells and pipelines and that [he methods are more flexible than any in use at the present time. Also, the methods are easily adaptable to automatic computers. INTRODUCTION The problem of calculating subsurface pressures in gas wells and along flowing pipelines has been studied by many investigators with the results that two widely-used methods have been presented in technical literature. One approximates conditions in a gas well or pipeline by assuming that temperature and compressi- bility are constants tor the entire gas column. The other method assumes that temperature is constant at some average value but permits compressibility to vary with pressure at the constant temperature. While these approximations may be justified for relatively shallow and low-pressure wells, they become more and more unrealistic as the calculations are applied to the deeper high-pressure wells. In wells or pipelines where there is an appreciable change in temperature between the inlet and outlet ends of the flow string, it is equally as important to consider the change in compressibility with temperature as it is to consider the change with pressure. Consequently, the methods presented in this paper were developed to provide a workable procedure for calculating pressures in gas wells and pipelines which makes no assumptions regarding either temperature or compressibility. The friction factors recommended for use with the equations were the result of study of published literature and extensive experimental work with gas wells. The F,. values in Appendix IV which contain the friction factor are equivalent to an absolute roughness of 0.0006 in. as calculated by the Nikuradse equation. The absolute roughness of 0.0006 in. was previously published by Cullender and Binckley2 for gas wells; it is in agreement with 0.00065 in. of Smith, Dewees, and Williams1 for gas wells and 0.00065 in. of Baker and Swerdloff4 for pipelines; it is in reasonable agreement with 0.0007 in. reported by the Bureau of Mines and the American Gas Assn.5 for large transmission lines. However, any type of friction factors may be used in the equations by a change in the F, values in Appendix [V].

Jan 1, 1957

By A. D. LeClaire

This paper claims to provide a description of diffusion processes in solids which is said to be a reformulation of Fick's Laws and therefore, presumably, is supposed to be as general as those laws. In fact, it appears to provide no more than an atomic model of a rather restricted type leading even to results in conflict with experiment. The restriction lies in the assumption, carried throughout the paper, that even in a chemical gradient the jump frequency i of an atom of species i is a function only of the composition on the plane from which it jumps, i.e., ?i = ?i(cl, c2 ...). This means that atom jumps in opposite directions from a site would occur with equal probability. There would then be no tendency for atoms to migrate preferentially in one direction along the gradient, so the model is incapable of accommodating the well established phenomenon of atom drift in a chemical gradient.10-" A more general model that does not suffer this difficulty was discussed in a paper13 I wrote in 1958, and the results therein already contain as a special case those given by Dr. DeHoff. The simplest sufficiently general assumption is to suppose that ?i is a function ?i(a1 a2,...; wl, w2, ..-) of the concentration aj and ? ?j at the site from which and to which, respectively, a jump is made. Any such function can always be expressed as a function of the sum and difference of its arguments. Thus d is the jump distance and g a geometrical constant. Obviously this is zero, i.e., no drift, if ??ri/??j = 0. X is written in this form, revealing two components of the total drift, because it can be shown that only the second component, depending on ??'i/???(?j -aj), actually contributes to the net diffusion flux Ji. This component can be shown,13 by a straightforward ther-modynamic transcription, to be responsible for the so called "thermodynamic factor" in the Darken approximation for a chemical diffusion coefficient is the activity coefficient of i. Because the jump rate ?i in DeHoff's approximation has no dependence on the concentration gradient it does not seem possible to derive the Darken equation from his Eq. [6] without the further rather arbitrary assumption that ?i = const ri. It is to be noted too that the author's derivation of Eq. [12] is only valid when ?i is in fact a function only of the cj at the plane from which the atom jumps—for only then is ci?i a unique function of position and therefore of A. Author's Reply R. T. DeHoff I am indebted to Dr. LeClaire for his penetrating discussion of my paper, "A Reformulation of Fick's First Law". I concede that it does appear initially that the relationship presented in my paper could be derived from the detail atomic model of random walk and atom drift presented in Dr. LeClaire's approach. However, there are some important differences in concept and viewpoint which deserve further amplification. Dr. LeClaire's description is penetrating, detailed, and fundamental. His approach describes an extremely complex phenomenon, the displacement of atoms in a multicomponent gradient, at a sophisticated level. For precisely these reasons, his analysis has not proved to be useful for experimental studies that have practical objectives. For example, in order to obtain the information required to complete the analysis of the jump frequency distribution in a ternary system, the following series of experiments would, I believe, be required: 1) chemical (gradient) experiments, covering the composition range;

Jan 1, 1970

By J. L. Zakin, G. K. Patterson, J. M. Rodriguez

Correlation has been obtained between drag-reducing characteristics for turbulent flow in a pipe and measurable properties of several polymer solutions. Several concentrations of high molecular weight polymethyl methacrylate in toluene, high molecular weight polyisobutylene in both toluene and cyclohexane, medium molecular weight polyisobutylene in cyclohexane and benzene and low molecular weight polystyrene in toluene were studied. Data obtained in these nonpolar solvents and literature data for more polar solvents were successfully correlated as the ratio of measured friction factor to purely viscous friction factor vs the modified Deborah number vrl/D0.2 where 71 is the first-mode relaxation time of the solution estimated by the Zimm theory. A shift factor which is a function of intrinsic viscosity 1/(4[?] - 1) allowed all the data obtained with nonpolar solvents to be correlated as a single function. For these systems, most of the data fit a single curve to within + 5 percent of the average friction factor ratio. The shift factor did not give a unique function of the data for the more polar systems. INTRODUCTION The phenomenon of drag reduction in polymer solutions was first studied by Toms1 in dilute solutions of polymethyl methacrylate in mono-chlorobenzene. The drag ratio for flow through circular tubes has been defined2 as the ratio of the pressure. drop of the solution to the pressure drop of the solvent at the same flow rate. The drag ratio is less than 1.0 for a drag-reducing fluid. Practical use of drag reduction is being made in fracturing operations in the petroleum industry.3 A more fundamental quantity is the friction factor ratio, defined as the ratio of the observed pressure drop to that predicted for a solution of the same viscosity characteristics and density at equal flow rates using the Dodge-Metzner friction factor equation4 Viscous solutions with drag ratios greater than 1.0 can have friction factor ratios less than 1.0. For practical applications, it is drag reduction which is of interest. However, for correlation the fundamental ratio is the friction factor ratio. In recent years, drag reduction has been studied extensively. Recent studies have shown that reasonable predictions of the incipience of drag reduction in polymer solutions can be made from the properties of the solutions and the flow Variables.5 However, it has not been possible to predict accurately the amount of drag reduction to be expected for a given polymer solution without any drag-reducing turbulent flow data on the same solution.6 For flow through circular tubes it is well established that there is a concentration effect and a diameter effect on drag reduction. Toms1 observed that drag reduction increases with an increase in the concentration of the solution up to an optimum concentration beyond which, due to the increased viscosity of the solutions, the drag ratio increased with an increase in concentration. Hershey 7 observed that for dilute Newtonian polymer solutions in nonpolar hydrocarbon solvents, a normal transition region may be obtained followed by a departure from the von Karman equation (on a friction factor-generalized Reynolds number chart). The point of departure is a function of diameter: the smaller tubes depart at the lower Reynolds numbers. Concentrated solutions may show no abrupt transition region, but merely an

By F. M. Stewart, F. H. Callaway, R. E. Gladfelter

In this paper oil initially in place is calculated by the various methods commonly used for analysis of water drive fields using data available as time progresses. Rate and pressure are predicted by means of the same methods using data available at the end of two years' history. These predictions are then compared with subsequent performance permitting an evaluation of the methods, which are Modified Schilthuis, Simplified Hurst, van Everdingen et al (1952), and the Electric Analyzer. INTRODUCTION Several variations of the material balance equation, differing in the term used to evaluate water influx, are in common use for estimating oil in place, predicting rate and volume of water influx, and forecasting producing rates and reservoir pressure in water drive reservoirs. The electric analyzer with an electrical network set up to simulate the oil reservoir and aquifer and their contained fluids may be used for the same purpose. Examples of the application of one or another of these methods have appeared in the literature. The accuracy and reliability of the material balance for calculating oil in place have been covered.' However, there have been few articles in which more than one method has been applied to an actual field allowing a comparison. It is felt that a field example, simple in nature, where the Modified Schilthuis, Simplified Hurst, van Everdingen et al (1952), and the Electric Analyzer have been applied would be of benefit in providing an evaluation of these methods as to their comparative usefulness and reliability in calculating initial oil in place and predicting performance. The Torchlight Tensleep reservoir is a small field in a large aquifer. The reservoir oil is greatly under-saturated, having a bubble point of only 55 psi and 2 cu ft/bbl of gas in solution. Changes in the reservoir volume factor in the range of pressures encountered are small, meaning little error in converting production to reservoir conditions. The pressure has declined from 1,618 psi initially to 137 psi during the first four and one-half years. Water production has been negligible. For Torchlight, the material balance equation as discussed later is considerably simplified by the omission of terms having to do with free gas. Thus with simpler equations, less variables to consider, the large pressure drop, the absence of a gas phase, and rapid pressure-rate adjustments, which mean an unusual amount of history in a short time, the reservoir appears suitable for comparing the methods listed above. GENERAL INFORMATION ON THE FIELD The Torchlight field is located on the eastern side of the Big Horn Basin, Big Horn County, Wyo., approximately 3 miles east of the town of Basin. The Tensleep reservoir was discovered in September, 1947. It lies at a depth of about 3,000 ft and produces oil of 35" API gravity. A total of five wells have been completed in the Tensleep, but only four are now producing. The reservoir is well defined in areal extent in that a total of 13 wells have penetrated the Ten-

Jan 1, 1955

By R. Simon, D. J. Graue

This paper presents correlations for predicting the solu-lility, swelling and viscosity behavior of CO2-crude oil sys8i.m~. The correlations were developed from experimental data obtained by the authors. These data are also presented. The data were determined by measuring the properties of mixtures of CO, and nine different oils. Experiinental conditions covered a range of 100 to 250°F and pressures up to 2,300 psia. Properties predicted by the correlations have average deviations, expressed as per cent of experimental value, of 2 per cent for solubility, 0.5 per cent for swelling and 12 per cent for viscosity. INTRODUCTION Interest in CO2 injection as an oil recovery process has led to the development of performance prediction methods which can be applied to specific reservoirs.1 iS To use these performance prediction methods, it is necessary to know the solubility, swelling and viscosity properties of CO2-crude oil mixtures at reservoir conditions. Some information on these properties has appeared in the literature; however, this information did not cover the range of different oils and conditions needed to prepare generalized correlations for reservoir engineering purposes. Consequently, an experimental program was undertaken to collect the data needed. The data obtained and the correlations developed from the data are described in the following sections of this paper. SOLUBILITY OF CO2 IN CRUDE OILS CO2 solubility data in the literature come from six principal sources. The solubility prediction method of Welker and Dunlop3 is limited to 80F. The information in Ref. 4 is of two types: the first includes binary and ternary mixtures of CO, and light hydrocarbons (C1 to C6), and the second gives data for CO1 and heavy hydrocarbons for a temperature range of 40 to 90F. Ref. 5 contains a KCO2 chart for systems whose convergence pressure is 4,000 psia. The KCO2's are based mainly on CO2-natural gas mixtures. Poettmann's work covered CO2 solubility in one condensate and one crude oil6,7 Ja-coby and Rzasa measured CO? solubilities as a function of pressure and temperature for two natural gas-absorber oil mixtures and two natural gas-crude oil mixtures.'8 CO, concentration in these four systems was fixed at 5 mol per cent. The work reported in this paper extends CO, solubility data to a variety of different crude oil types in a temperature range from 110 to 250F and pressures up to 2,300 psia. The experimental procedure used by the authors to obtain the solubility data consisted of combining known amounts of pure CO, and crude oil in a visual cell at a fixed temperature and measuring the bubble point of the mixture. Measurements were made for a total of 40 different CO2-oil mixtures and the results are shown in Table 2. The mixtures included nine different oils (seven crude oils and two refined oils) whose properties are listed in Table 1. All nine oils had vapor pressures less than 1 atm at the experimental temperatures. Consequently, analysis of the bubble-point vapor showed a CO, concentration over 99 mol per cent. At no time during these experiments was a second, more dense, liquid phase observed. The solubility correlation which was developed from the data in Table 2 is presented in Figs. 1, 2 and 3. In these figures, solubility is expressed as xco2 the mol fraction of CO, in the CO2-oil mixture. Fig. 1 shows solubility as a function of CO2 fugacity6 and temperature. Fig. 2 shows the same solubility data expressed as a function of saturation pressure and temperature. The solubility shown in Figs. 1 and 2 is for an oil whose UOP characterization factor is 11.7. UOP characterization factors of crude oils can be determined from Ref. 10 if the viscosity and APT gravity of the oil are known. Fig. 3 gives the solubility correction factor for oils whose UOP characterization factors differ from 11.7. The solubility correlation in Figs. 1, 2 and 3 predicted

Jan 1, 1966

By S. Gilbert, G. R. Bailey

A further evaluation of the bomb-sampling method for determining the oxygen content of liquid steel is presented. The results of this study and their close agreement with the results of an earlier evaluation confirm the conclusion that the bomb-sampling method is valid for obtaining representative samples for the determination of the oxygen content of a liquid steel bath. WHAT constitutes the most desirable procedure for obtaining a sample suitable for determining the oxygen content of a liquid steel bath has been a controversial subject for several years. In 1952 Huff, Bailey, and Richards' described a modification of the bomb-sampling technique originated by McCutcheon and Rautio.' In both the modified and original techniques, a small cast-iron or steel mold containing aluminum wire and appropriately covered is inserted into the furnace, coated with slag, and then plunged into the metal bath. Upon entering the metal, the cover melts and a sample of the steel bath enters the mold. The data presented by Huff, Bailey, and Richards' indicated that reproducible samples could be obtained by their method. Furthermore, the oxygen analyses from samples obtained by their method agreed better with those from controlled laboratory experiments than did analyses from samples obtained by methods previously suggested for sampling large liquid-metal baths. Most techniques, other than bomb-sampling, require that a sample of liquid steel be removed from the furnace in a well slagged spoon and poured into an iron mold containing aluminum or into a massive copper mold for rapid chilling. Pouring in this manner requires that the sample pass through the air. The controversy, then, is somewhat as follows: Proponents of the spoon-sampling method and similar dip-and-pour methods feel that the introduction of a cold steel mold into a molten steel bath may result in a localized boiling condition that may deplete the steel of oxygen to a significant degree in the area where the bomb is introduced. Conceivably this boil could cause results that are, on the average, too low and nonrepresentative of the bath composition. On the other hand, samples that are spooned and then poured through the air may also be nonrepresentative because of oxidation by the atmosphere. The restrictions imposed in sampling with a spoon are much more stringent than those imposed when sampling with the bomb-type mold within the furnace. The spoon sample must be taken in a well slagged spoon, a requirement that depends on the condition of the slag in the furnace. Also, the samples must be poured as quickly as possible, without shaking the spoon and without allowing slag to enter the mold. The necessity of fulfill-

Jan 1, 1955