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By E. W. Newman

During 1943 and 1944, there was an urgent need for certain grades of optical calcite (Iceland spar) for instruments for ' military uses. To find a supply of this material, prospecting was carried out in Montana, California and Colorado. Although some production was obtained by the work in California, the best results were from prospecting the large calcite veins of south central Montana. The bulk of the optical calcite mind during World War II has come from that area. The Bureau of Mines took an active part in the search for optical calcite in Montana. It examined most of the known calcite veins in the 70-mile distance between Wilsall, on the Shields River: and Absarokee, on the Still water River, and conducted exploration on several of the deposits. The Geological Survey also took an active part by mapping many of the veins. Actual mining of the calcite was performed at first by Calcite Operators, Inc., and later by the Metals Reserve Co., through an agent. A sorting plant was established at Clyde Park, where custom material could be sold. These activities stimulated mining by private operators. To be suitable for military uses, the calcite mined had to meet rigid specificstions as to both size and quality. Individual crystals had to be clear and transparent and if in the form of rhombs had to measure at least 7/8 in. on each edge. Some color and a few inclusions in the calcite were allowable, but material with incipient or developed cleavages, or showing twinning other than parallel to the base, was unacceptable. History of Deposits The existence of large veins of calcite in south central Montana has long been known, and for many years the farmers of this region have used the common vein calcite for producing grit for chicken feed. According to reports, the fist optical calcite produced from Montana came from the Cartwright deposit near Grey-cliff,' but until recently the mining of optical calcite in Montana has been limited to spasmodic searching for small crystals suitable for making nicol prisms for saccharimeters and microscopes, or for mineral specimens. The possible need of substantial amounts of optical calcite for military uses began to appear late in 1942 and early in 1943, therefore the Polaroid company began searching for a source of supply in Montana and California. Work on the Wade property near Clyde Park was started on a small scale in the fall of 1942, by .4. H. Hansen, of Clyde Park. During the winter and spring of 1943, a modest quantity of optical calcite was mined and shipped to the Polaroid Corporation, Cambridge, Mass. Most of this was produced from the "Hansen vug," which was found close to the surface. Early in the summer of 1943, mining on the Wade property was undertaken by Calcite Operators, Inc., a company organized for mining optical calcite from the

Jan 1, 1948

By R. J. Pfister

The development of a water-input profile instrument based on the introduction of brine and fresh water into an input well with the electrical location of, the boundary developed between them is reported. Two methods are available in the use of this instrument to measure the foot by foot water-intake rates of the various sand strata: the moving boundary method in which variable well bore diameters can be determined and/or cancelled out and the constant boundary method. The type of results obtained and the relative advantages of each of these methods are described in detail. Representative data are included covering the use of this instrument in experiments involving selective acidizing, selective plugging, and selective shooting. In such experiments, this instrument has been used to diagnose the unfavorable distribution of water intake in input wells and also to determine the effectiveness of the resultant treatments. The data included also serve to illustrate the type of problems which can be studied with this technique. Introduction For ten years or perhaps longer a number of progressive water-flood operators have felt the need for some to to measure the foot by foot water-intake rates of various strata in water-injection wells. The primary need is to diagnose unfavorable water distribution in various strata and to evaluate the effectiveness of the corrective measures such as selective acidizing, selective plugging, and selective shooting. Previously described methods for obtaining this type of data were not considered entirely adequate.l,2 The profile equipment described in this paper embodies the separate introduction of brine and fresh water into the well at carefully measured and controlled rates and the electrical location of a sharp boundary developed between these fluids. At present this instrument is a research tool of value in determining the effect of various well treatments on an individual sand strata. lts primary use has been on wells in which different sections require different treatments (e.g., wells with an open sand to be plugged and a tight sand to be acidized)- It has, thus, made possible the determination of a rearrangement of the water intake of a well. The instrument can also be used to direct the treating material into a given zone. In completing a well the less permeable sands are shot more heavily with nitroglycerine in order to equalize the water intake between the permeable and less permeable sands. The extent to which such corrective shooting has been successful Can be determined by a water-input profile. The combined profile and well-bore diameters should also provide a method for determining the direction and effect of various selective shooting techniques. Equipment The essentials of the water-input profile technique for measuring the intake per foot of individual sand strata are the injection of a nonconducting fluid, water, at the top of the well and a conducting fluid, brine, through a separate string of

Jan 1, 1948

By Lester L. Hirst, Arno C. Fieldner, Henry H. Storch

EXPERIMENTAL work on liquefaction of coal was taken up by the Bureau of Mines in 1936 when it became evident that a prudent policy from the national point of view should include preparation for the time when gradual exhaustion of petroleum resources would require supplementing the growing demand for motor fuel with gasoline and diesel oil from coal. At that time (1936) certain foreign nations that had no home sources of petroleum, especially Germany, England, and Japan, were conducting active research and at least two of them were producing liquid fuel from coal on a commercial scale. Germany was reported to have an annual producing capacity of 800,000 metric tons of gasoline per year, and England had just put into operation the Billingham plant of Imperial Chemical Industries for the hydrogenation of bituminous coal and tar by the Bergius-.I.G. process. The annual capacity of this plant was about 150,000 long tons of gasoline per annum (3500 bbl. per day). With these developments taking place in foreign countries, it seemed important to undertake a long-range program of fundamental research in this country to establish a sound groundwork for the evaluation of foreign work on synthetic liquid fuels and at the same time to obtain data on the oil yields and operating difficulties using various kinds of American coals and lignite to the hydrogenation process. The results of such research would be useful in determining the yields and quality of liquid products obtainable from various coals so that American industry would be in position to select the most suitable coals and make rapid progress in establishing this new industry when the commercial need should arise. It was hoped, also, that progress in a better understanding of the chemistry of coal hydrogenation would reduce the cost of the process materially. To carry out this program, a small continuous unit capable of hydrogenating 100 lb. of coal in 24 hr. was installed at the Central Experiment Station of the Bureau of Mines at Pittsburgh, Pa. Small steel autoclaves or bombs of 0.3 gal. (1.2 liters) capacity also were used for batch-hydrogenation experiments in the study of the chemical fundamentals of the process. Much valuable assistance was obtained in planning the experimental program and designing the equipment from the Fuel Research Station of Great Britain and the Fuel Laboratories of the Mines Department of Canada, where such investigations had been in progress for several years. EQUIPMENT AND GENERAL PROCEDURE OF RESEARCH The industrial liquefaction of coal by the Bergius-I.G. hydrogenation process as practiced at Billingham, England, from

Jan 1, 1944

By G. A. Croes, N. Schwarz

The dimensionless groups, to which the variables that govern the displacement of oil from reservoirs by liquids can be combined, are derived. Three types of displacement are considered, viz. cold-water drive, hot-water drive and solvent injection. The derivation of the dimerzsionless groups is carried out by means of the relevant basic equations (in-spectional analysis). The resulting sets of groups are afterwards completed by means of dimensional analysis. The form of the groups is given in such a way that they can be adapted to suit the various boundary conditions that are encountered in practice. The physical meaning of the groups is discussed. They have all been brought together on a chart, from which their mutual relation and their corresporzdence to related dimensionless groups in common use in other engineering sciences can be read off. The limitations of dimensionally scaled model experiments as a useful tool for studying liquid flow in porous media, as occurring in oil reservoirs, are discussed. The use of models to study fluid mechanics has an appeal for everyone endowed with natural curiosity. What active boy has not played with ship and airplane models, or crude models of dam and drainage systems Even in the most advanced technical engineering, such models play a fundamental and indispensable role. "And yet in few departments of the physical sciences is there a wider gap between theory and practice, between scientific knowledge and the state of art, than in the use of models to study hydrodynamic phenomena." Garrett Birkhoff1 INTRODUCTION Laboratory displacement experiments are extensively used to investigate, directly or indirectly, the production behavior of petroleum reservoirs. Such experiments are representative of the reservoirs as a whole, if they are carried out with models that are "properly scaled." The performance of oil reservoirs is governed by the values of a number of variables, which can be combined to dimensionless groups. Two general methods are available for the derivation of these groups. In the first of these, dimensional analysis, combination of the variables is done essentially by trial and error. Its only premise is knowledge of the complete set of relevant variables. In the second method, inspectional analysis, the dimensional homogeneity of the equations describing the behavior of the system to be studied is used. The resulting dimensionless groups can be divided into: (a) independent (variable) groups, such as dimensionless length, time, etc.; (b) dependent groups, giving the dimensionless form of the variables, such as recovery and pressure, that can, at least in principle, be measured during an experiment; (c) similarity groups, which are independent constant groups, such as ratio of length to height of the reservoir and ratio of

Jan 1, 1957

By E. I. Salkovitz, F. W. von Batchelder

DURING the last few years several papers1-' have been published in which internal friction measurements have been used to determine the quantity of carbon or nitrogen dissolved in a iron. This method is based on the fact that, in pure Fe-N and Fe-C alloys, nitrogen and carbon cause peaks in the internal friction vs. temperature curve; at a frequency of 1 cycle per sec (cps) these peaks appear at $-200 and +360C, respectively, and if internal friction is expressed as Q-1, which is equal to times the logarithmic decrement, this figure will, by coincidence, give the weight percentage of nitrogen or carbon in solid solution.' In most of the studies published, very pure iron (Puron) was used. In one case the influence of manganese on the behavior of nitrogen in a iron was mentioned.4 It would be of great value, especially for the study of aging and related phenomena, if this method could be applied to commercial mild steel with norrnal percentages of manganese, phosphorus, sulphur, etc. As a rule, in such steels carbon and nitrogen are present together, and the amounts of these elements in solid solution should preferably be determined separately. The fact that their internal friction peaks appear at different temperatures (+36° and + 20°C in pure iron) seems promising for such a selective determination. It is necessary, however, that the peaks are narrow enough not to interfere with one another, and further, that there is no effect from carbon on the behavior of nitrogen in stress induced diffusion, and vice versa. According to Fast,' however, in the presence of manganese the nitrogen peak gets wider and appears at a higher temperature nearer the carbon peak, and thus the prospects for selective determination are reduced. (The carbon peak was not affected by the presence of manganese.) But even if fully quantitative de- terminations of the two elements are not attained, some relative figures on the sum of them and an indication of which one is the predominant one, would be of value. Some results from experiments along these lines will be reported here. An internal friction measuring device was assembled mainly following a description by KG." The measurements were also carried out as reported in that paper. Table I gives the chemical compositions of the four different materials used in this investigation. All materials were drawn to wires with diameter about 0.8 mm, and the analyses refer to these final shapes. Determination of Nitrogen Peak Wires from steels A, B, and C were decarburized in wet hydrogen (about 30 pct H2O) at 700°C until no carbon or nitrogen could be found by chemical analysis. No peak was then found in the internal friction. The wires were further annealed at 580°C for 16 hr in hydrogen bubbled through a solution of 6.8 pct NH3 in distilled water. Chemical analyses gave 0.04 pct N in A and C, and 0.06 pct in B. After annealing at 580°C for 15 min in a lead bath and water quenching, the internal friction was immediately measured. The resulting curves are shown in Fig. 1. At these high values of the internal friction the accuracy is comparatively poor; at Q-1 - 0.030 it is estimated to be 0.002. In order to make possible a calculation of the activation energy for diffusion of nitrogen, measurements were made at two different frequencies. Steel A shows rather broad peaks, and their temperatures can hardly be expected to be very accurate. Steels B and especially C are better in this respect. The finding of Fast' that manganese broadens the nitrogen peak is con-

Jan 1, 1953

By G. D. Boozer, W. H. Somerton

RESEARCH CORP., LA HABRA, CALIF. Thermal diffusivities of some typical sedimentary rocks have been measured by a rapid unsteady-state technique. Thermal data including diffusivity and conductivity are presented for the temperature range of 200" to 1,800°F. Diffusivities calculated from steady-state conductivity rneasurernents compared favorably with unsteady-state data at the lower temperatures. Unsteady-state data are less reliable at higher temperatures; reported values may be as much as 20 per cent high at temperatures in excess of 1,500°F. This is caused partly by the simplified method used in calculating diffusivity from experimental data and partly by the many thermal reactions which occur at the higher temperatures. The marked decrease in thermal diffusivity and conductivity at elevated temperatures indicates the importance of considering the temperature dependence of thermal properties in subsurface heat-transfer calculntions. Knowledge of the effects of liquid saturation, overburden and pore pressures, and heats of reaction of reservoir materials will be required before complete subsurface thermal analyses may be made. INTRODUCTION Heat-transfer calculations are becoming increasingly important in the analysis of in situ combustion and underground nuclear explosions. Thermal data for natural rock materials at elevated temperatures are generally unavailable. Calculations at high temperatures may be grossly inaccurate if temperature-dependent thermal properties of rocks are not considered. It is known that the heat capacities of rocks increase with temperature. Heat capacities may be calculated from chemical or mineralogica1 analyses of the rock system. Thermal bulk expansion of rocks is believed to be small, although few data are available. Thermal conductivities of most natural rock materials decrease with increased temperature. Thermal diffusivity, defined as the thermal conductivity divided by the product of the heat capacity and the bulk density of the material, is used in unsteadv-state heat-transfer calculations. It is apparent that thermal diffusivity decreases markedly with increased temperature. A new method, which gives a nearly continuous record of thermal diffusivity within the temperature range of 200° to 1,800°F and requires less than 1.5 hours for the run,' was used to measure the diffusivity of several sedimentary rocks. Thermal conductivities were calculated from measured bulk densities, heat capacities calculated from chemical analysis and the measured diffusivity values. Thermal conductivities were measured at lower temperatures by a steady-state technique1 to test the agreement of data obtained by the two methods.

By A. F. Henderson, C. F. Cornell, A. F. Dunyon, D. A. Dahlstrom

IN processing magnetic taconites several steps of crushing, grinding, classification, and magnetic separation are required to produce a 60' pct Fe concentrate. Usually the final concentrate is in a slurry form of 55 to 70 pct solids by weight and is further characterized by a particle size of 60+ pct —325 mesh. In taconite plants already completed or under construction the conventional method used to obtain pellets suitable for blast furnaces is to filter the concentrate slurry, ball the filter cake, and then harden the green pellets in a traveling grate or in a vertical shaft furnace. Large tonnages must be handled in minimum floor space, with reduced maintenance and lowest possible operating cost. Filtration must therefore achieve two objectives: I) high filtration rate—in terms of pounds of dry solids per hour per square foot of filtration area—at a low filtrate solids concentration, and 2) a filter cake moisture that will always permit efficient balling within the normal fluctuations of ' plant operating conditions. If moisture contents are too high, balling may be impossible or result in a mushy ball .without enough green strength for the firing operation. Development work has met these objectives. At low investment and operating costs, filtration rates of 250 to 600 dry lb per hr per ft2 have been attained for concentrates of 60' pct —325 mesh. By combining the disk-type continuous filter with proper agitation, the Agidisc filter produces a homogeneous filter cake, easily discharged from the disk sectors. This application provides the lowest initial cost per square foot of filtration area, minimizes floor space, reduces down time for changing filter media to a negligible factor, and simplifies process control and maintenance for the operator. It is now possible to predict very closely the taconite concentrate filtration rates for a wide variety of conditions—either by experience or with a few simple leaf tests. When balling and pelletizing operations began on a continuous basis, it became apparent that moisture content of the filter cake was a critical factor and must always be controlled by the filter operator below some maximum allowable value. Accordingly the Reserve Mining Co. and the Eimco Corp. joined in a study of the many variables affecting filter cake moisture content. The study was conducted at the Reserve Mining Co. taconite plant at Babbitt, Minn. To process plant tonnage the Babbitt plant utilizes a 6-ft diam Agidisc filter with six disks and an 8-ft diam drum filter with 10-ft face. However, most of the plant filter investigations were made on the Agidisc because of its superior performance. A considerable amount of small-scale test work was first carried out to study more closely the individual variables and ascertain their effect on filter cake moisture content. A general correlation method was then developed which allowed reasonable prediction of moisture content at any operating conditions. This step was made necessary by the fact that in full-scale filtering, operating variables usually interact to produce a combined rather than a singular effect. Studies were then made on the full-scale filters to prove the validity of the correlations developed, and past operating records were examined to ascertain whether or not significant variations could be traced to any single factor or to a combination of factors.

Jan 1, 1958

By John G. Hall

The pumping operations at the Chief mine have been unique in the respect that for many years the entire flow of water into the mine has been disposed of by pumping into natural underground "caverns" or "sinks." Volumes up to 4000 gpm have been pumped into these caverns with no apparent tendency for the caverns to fill with water, and it has never been proven that any of the water returns to the mine workings. Major pumping operations have been carried on during two periods, the first from 1918 to 1927, and the second from 1942 to the present time. Early Pumping Operations CHIEF MINE The Chief Consolidated Mining Co. was organized in 1909, and for the following nine years ore was developed and mined from the 600 level down to the 1800 level, all above the permanent water table, the 1820 level. The ore occurs as extremely-irregular pipes of replacement ore in limestone, and to date a total of approximately 2 1/2 million tons of ore has been produced. The ore was highly oxidized down to the permanent water level, and some highly-oxidized ore runs occur beneath the permanent water table. In 1916, with extensive mining being done on the 1800 level, 20 ft above the water table, there were indications that a zone of secondary enrichment might exist below the water, and in order to follow the ore runs to greater depth, it was realized that arrangements would have to be Made to pump water to the surface. The original pumping installation was designed to pump 350 gpm in five stages against a 1900-ft head to the surface. By January 1919, the water had been lowered to the 1900 level and an excellent grade of silver-lead ore was being produced from the zone of secondary enrichment. At this point. the flow of water equalled the capacity of the pumps, and pumps of an additional 1000 gpln were installed to supplement the original system. By January 1920, the water had been lowered approximately 100 ft, and the total flow of water was 1000 gpm. The water was being pumped from many different places in the mine where ore was being followed downward, with 27 different pumps operating below the 1800 level, mainly Cameron air-driven sinker pumps. These first sinking pumps were cumbersome and inefficient, and each of the larger pumps weighed approximately three tons and required tremeridous volumes of compressed air. During this period, an exploration drift being extended north and west from the Chief shaft on the 1600 level encountered a large natural cavern some 2000 ft from the shaft. This cavern in places measured 60 ft in diameter. Sometime later the disposing of water into this cavern was suggested, and as an experiment to determine the results of such an operation, an attempt was Made to fill the cavern by pumping in a small volume of water, but the water disappeared as fast as it was discharged into the cavern. It was decided then to try the cavern as a drainage outlet for the entire volume of water being pumped to the surface, and the water apparently did not return to the mine workings. Subsequently water up to 3000 gpm was pumped into this cavern. An attempt was made to determine whether any water was being returned from the cavern to the lower workings, and 100 lb of sodium fluorescein salt was added to the water discharged into the cavern, but no trace of it was found in the drainage water in the mine. Results of another such test will be described later.

Jan 1, 1950

By C. H. Li, J. Washburn, E. R. Parker

Yield stress in single crystals of zinc was shown to be dependent on prior annealing temperature and rate of cooling after annealing. Rate of strain hardening beyond the yield was not sensitive to annealing procedure. A tentative mechanism for the effect was discussed. COMPARATIVE mechanical tests of metal single crystals generally show a large scatter of results. Many factors may contribute to this variation. The present investigation was undertaken to evaluate the influence of two factors not ordinarily considered of major importance—annealing temperature and cooling rate after annealing. Since plastic properties of crystals are thought to depend on the presence of lattice imperfections, it follows that a variation in properties should result from differences in the distribution and density of these imperfections. Furthermore, in the light of current theories of interaction between edge dislocations and lattice vacancies,' it seems possible that annealing temperature and subsequent rate of cooling might play a part in this distribution. Analysis of the effect of these variables on plastic properties may lead to a better understanding of the annealed state. Single crystals of zinc which have been strained in simple shear undergo complete recovery of mechanical properties upon subsequent annealing. This behavior is useful because a single specimen can be used repeatedly, thus eliminating the uncontrollable variables introduced by the use of many crystals. The test section of the crystals used for these experiments was a cylinder 1/8 in. thick with a cross-sectional area of about 1/3 sq in. The specimens were acid-machined from spherical single crystals 1 in. in diameter in such a way that the slip plane (0001) was at right angles to the axis of the cylinder. In testing, a shear stress was applied along one of the slip directions, [2110] in the (0001) plane.' All crystals, unless otherwise noted, were grown in a helium atmosphere from molten 99.99 pct pure Horse Head Special Zinc. Fig. 1 is a family of curves obtained from one crystal. Each curve was obtained by deforming the crystal to 10 pct strain at a rate of 3 pct per min, following an anneal of 1 hr at 260°C. The strain direction was reversed every other time so that no progressive change in shape of the specimen took place during the series of tests. Since the stress-strain curve was reproducible within a fairly narrow range under the same conditions of annealing, it was then possible to determine the effect of changes in annealing conditions. A crystal was tested repeatedly as previously described but the annealing temperature and rate of cooling preceding each test were varied (Fig. 2). Two cooling rates were used, approximately 30°C per min and 3°C per min. Annealing was conducted at three temperatures, 200°, 300°, and 400°C. For a given annealing time and rate of cooling the room temperature flow stress was higher the higher the annealing temperature. The increase in flow stress was small as the annealing temperature was increased from 200° to 300°C but rose rapidly when the annealing temperature was raised from 300" to 400°C. Faster cooling from the high temperature produced an even greater strengthening of the crystal. The curves were obtained in the order indicated by the numbers. The stress level associated with a certain annealing treatment was, within the limits of scatter, always the same regardless of the

Jan 1, 1954

By P. M. Kelly, E. P. Butler

The stability of a 70/30 Mn-Cu alloy aged to peak damping has been investigated using electron microscopy, X-ray diffraction, and torsional pendulum measurements. Storage at room temperature or at 100" C causes a reduction in damping capacity. This is shown to be due to the formation of subdomains which "lock" the main domain structure and so hinder their movement. After storage the damping capacity can be restored by a retransformation treatment, which generates structures identical to those found in newly aged specimens. Plastic deformation by rolling also causes a decrease in damping capacity. In this case the damping capacity can only be restored by retransformation if the amount of deformation is less than about 5 pct. THE general metallography and structure of these high damping capacity alloys has been discussed in Part I of this work.1 Part II deals with some of the variables that affect the damping capacity. In particular, the stability of the damping capacity of a 70/30 alloy aged for 2 hr at 425° C and quenched has been investigated. The temperature sensitivity of the damping capacity of a 70/30 alloy aged for 2 hr at 450° C has been reported by Birchon.2 The damping capacity begins to decrease with increasing temperature, and is very low above the M, temperature of 125°C. The cubic — tetragonal transformation is completely reversible and there is no apparent thermal hysteresis associated with the change in damping capacity. Another important effect was first reported by Dean and his coworkers.3 They noticed a decrease in the damping capacity with time for specimens of a quenched tetragonal alloy. More recently workers at the Admiralty Materials Laboratory 4 have studied the stability of an aged 70/30 alloy. They found that the damping capacity decreased to half its original value after about 1000 hr at room temperature. EXPERIMENTAL The techniques used for electron microscopy and X-ray diffraction have been described in Part I. The damping capacity was measured by means of a torsional pendulum, using rectangular specimens, 3 by 0.3 mm with a 6 cm gage length. The specific damping capacity, S.D.C., was calculated as a percent amplitude decay in free vibrations over 10 cycles, starting at an amplitude which corresponded to a 700 psi surface shear stress. Because of the stress dependence of the damping,' the values obtained were about a third those reported for a 5000 psi surface shear stress.' RESULTS a) Effect of Aging Temperature. The effect of aging temperature on the damping capacity is shown in Fig. 1. The damping capacity reaches a peak of 12 pct after aging at 400° to 425°C) then begins to decrease as the volume fraction of a Mn increases. At higher aging temperatures the structure becomes cubic again with a low damping capacity. b) Stability of the Aged Structure. The damping capacity of the aged alloy decreases with time at room temperature. This process could be accelerated by storing at 100°C, when about 100 hr were required for the damping to fall to half its original value. The results of room temperature and 100°C storage, for times up to 1000 hr, are shown in Fig. 2. The damping capacity starts to decrease after about 24 hr at 18° C and 1 to 2 hr at 100°C. It was found, however, that the damping could be almost completely restored by retransformation. The specimens were held at a temperature above the M, for a short time, 250° C for 5 min, and then quenched. The values of damping capacity for specimens that were aged, stored, and then retransformed are shown by the full points in Fig. 2. X-ray measurements of the c/a ratio and hardness readings on the specimens did

Jan 1, 1969

By D. J. Pye

Certain high molecular weight synthetic polymers in very dilute solutions decrease water mobility in porous media 5 to 20 times more than would be expected from the solution viscosity. This indicates that increasing water viscosity to reduce adverse mobility ratios in water floods is economically feasible in many situations. Laboratory results are consistent with accepted theory with respect to improved areal sweep, permeability distribution and displacement efficiencies as would be predicted from the solution mobility measured in the core. The laboratory results have been confirmed by field pilot floods which recovered 80 per cent and 100 per cent more oil than comparative water-flood pilots in fields containing 16 cp and 130 cp oil respectively. Economic analyses based on pilot data indicate the method to be profitable. INTRODUCTION The desirability of improving the water-oil mobility ratio in waterflood-ing operations has long been appreciated, especially for high viscosity crudes. Methods of reducing the oil viscosity by application of heat, gas resaturation and miscible drives have met with some success. Conversely, it has been generally conceded that increasing the water viscosity would also be effective, but the amount of thickening agent required to effect an appreciable increase in viscosity is discouragingly high. The use of such materials as glycerin, sugar, or glycols is completely out of the question economically, so that considerable attention has been given to the use of the much more efficient synthetic water-soluble polymers as viscosity improvers; but even these materials are not economically attractive. If increased water viscosity could be economically realized, marked improvements in areal sweep efficiency, as discussed by Caudle and Wittel and others, would be realized in field operations. Similarly, the improved mobility ratio would bring about increased recoveries by correcting permeability distribution problems as discussed by Stiles2 and Dykstra and Parsons,' and improvements in displacement efficiency would be obtained as recognized by Buckley and Leverett4 and Welge.5 LABORATORY STUDIES THE RESISTANCE EFFECT In the course of research to develop a more efficient water-soluble polymer viscosity builder, we discovered that a very few types of water-soluble polymers exhibited a most unusual and very interesting property not previously observed. Among the earliest materials showing such activity were polymers containing acry-lamide. Fig. 1 shows a typical plot of the solution viscosity vs concentration for one of these polymer solutions as determined in an Ostwald viscometer. As usual, such a plot is an approximate straight line on semi-logarithmic paper. Now, an inspection of Darcy's law, shows that a viscosity value can also be determined in a formation sample if the pressure, flow rate and permeability are known. If the core permeability is previously determined with wa- ter or brine, then the viscosity of another aqueous fluid may be determined from the equation. The viscosities so determined for glycerin (glycol or polyvinyl alcohol solutions, for example) agree with the viscometer determinations. However, in the case of the water-soluble polymer solutions in which we are interested, the viscosities measured in the formation sample depart very markedly from the viscometer values. A typical relationship for a polymer solution is also shown in Fig. 1. This unusual departure from the expected response is referred to as a resistance property of the polymer and is quantified as "resistance factor". Since the resistance factor R can best be determined in a core under study, the term has been defined on the basis of the ratio of the brine mobility to the polymer solution mobility at residual oil saturation so that:

Jan 1, 1965

By T. P. Papazoglou, N. A. D. Parlee, W. C. Phelps

PRACTICAL designs for good "home made" molybdenum furnaces are hard to find in the literature. The one described briefly below left something to be desired but was good enough to operate as a rather long (30 in.) two-zone furnace for periods of over 2 months at temperature (1400° to 1600°C) without shutdown. The principal problem in our application was to establish a temperature profile with two distinct constant-temperature zones and no dip between the zones. This and other problems mentioned below would not arise, however, if both zones were operated at the same temperature and if a shorter furnace were acceptable. Since molybdenum windings oxidize very rapidly when heated in air, impervious refractory tubes were used for both the furnace core and the outer jacket tube shown in the accompanying figures. A protective atmosphere of forming gas (10 pct H2, 90 pct N2) was continuously passed through the gas-tight annular volume between the core and outer jacket. The water-cooled copper ends shown in Figs. 1 to 3 sealed the ends of the tubes. Annealed molybdenum wire (40 mil) was wound on the recrys-tallized alumina core (35.5 mm OD by 28.5 mm ID by 30 in.) at a spacing of 0.36 in. The spacing was reduced to 0.29 in. close to the ends to partially compensate for end heat losses. Fig. 2 shows two molybdenum-ground lead taps off the center of the winding to produce the two independect temperature zones. The ground lead was insulated with 1/4-in. alumina tubing and connected to the grounded copper end by passing the wires through the gas port tube and crimping each wire into notches cut at the mouth. To prevent sagging of the core at high temperatures, refractory "troughs" were cut from alumina and mullite tubing to cradle the core. The support "troughs" which were 6 in. long and located about 5 in. from each end of the annular volume also served as radiation shields. In view of the different expansion coefficients and operating temperatures of the core and outer jacket (3.5 in. OD by 3 in. ID by 30 in.), the ends of the tubes were smoothed and squared to produce good sealing surfaces, and the core was ground 1/32 in. shorter than the outer tube. The power terminals were passed through their respective conductor ports which were internally lined with alumina tubing and sealed with Armstrong adhesive A-6 leaving about 1 in. of protruding lead wire for external connections. (Adhesive A-6 is a two-component system consisting of an epoxy-type resin with a mineral fibrous filler and an amine catalyst.) Figs. 1 and 3 show the entire assembly of concentric refractory tubes, copper ends, and sealing o rings, held together with two brass flanges and 3/8-in. bolts with heavy springs for dimensional flexibility. The furnace shell (19 by 19 by 30 in.) consisted of a steel frame with sheets of transite forming a box. The copper ends protruded through two 3.75-in. circular holes cut at the center of each transite square end. Thermal insulation next to the transite exterior was effected by K-23 B&W bricks alld in a central volume of approximately 9 by 9 by 30 in. a row of K-30 bricks was lined up to support the hot assembly. The rest of the volume around the outer

Jan 1, 1965

By Gordon I. Gould

The treatment of quicksilver ores to extract the metal, for centuries one of the fundamentally simpler metallurgical operations, has undergone few if any material changes during the past iew decades other than improvement and change of type of equipment used. Of almost universal application and as the seldom deviated from process, the roasting method is still considered superior to chemical metallurgy. Likewise, roasting of the crude ore without previous beneficiation continues to be standard practice, although some successful operations have employed concentration prior to roasting. The roasting process has been carried out in a variety of equipment, devised for different tonnage capacities, to treat "special" ores, and to satisfy an inventive notion of the particular builder, but during the past 25 years there has been one outstanding change in roasting equipment. This change, though neither originating in nor confined to the United States, has probably been developed and applied to a far greater extent in this country than in any other mercury-producing country of the world. The change from manually or gravity operated furnaces, mostly huge brickwork affairs justified largely by simplicity, lack of power and mechanical requirements, and occasionally by excellent metallurgical results, to mechanical furnaces, began actively during World War I under the stress of requirements for in- creased production, a shortage of labor, 2nd other factors to be brought out later. During the twenties the change to mechanical furnaces became nearly complete at American mines with the development of several types, the rotary furnace predominating. During the thirties, and the period of low prices in the early part of this period, few changes were made other than mechanical improvements and an almost complete acceptance of two types: the rotary furnace and the hearth or Wedge furnace. These two types have been developed to a high degree of metallurgical efficiency, have proved to be mechanically simple and have far greater flexibility and lower operating costs than pre-World War I furnaces. Of the two types the rotary is the more popular, about 30 rotaries having been in operation in the United States in 1943 as compared with about six hearth-type furnaces. The units of smaller capacity for roasting mercury ores have almost without exception been indirectly fired, such distinction being commonly accepted as the difference between retorts and furnaces, which are fired directly. The difference between indirect and direct firing obviously permits of quite different conditions surrounding the ore being roasted in relation to the chemical reaction to take place. In the indirect-fired unit the ore is contained within the body of the retort in a stagnant if not completely oxygen-impoverished atmosphere. In the direct-fired furnace the ore is in contact with the gases of combustion, which may easily (if not too easily) be supplied with an excess of

Jan 1, 1944

By J. M. Schopt

COAL petrology is the study of the lithologic composition and texture of coal and includes megascopic as well as microscopic differentiation. Coal petrography is a quantitative study, principally (but not exclusively) microscopical in nature. The distinction between coal petrologic and coal petro-graphic studies usually is not important, but it is important to recognize that these studies differ materially from other types of petrology that deal primarily with minerals. The petrologic entities* of coal are less clearly distinguished than most minerals and the basis of distinction is not always clearly expressed. The relation of coal petrology to geologic, mining, and technologic problems is most evident when results of coal petrologic studies can be stated quantitatively. The chemical and physical composition of coal and the determination of its quality and properties are continuing problems. The source of these problems lies in the heterogeneity of coal and in its almost complete insolubility in ordinary solvents at normal temperatures. The empirical and comparative character of standard chemical coal analytic values is one of the consequences resulting from heterogeneity and insolubility of coal. Nevertheless, these coal analytic methods are highly technical and diversified. Coal petrol.ogy employs a group of similar analytical methods which provide information about coal that the other methods cannot supply. The heterogeneity of coal is most clearly demonstrated by means of petrologic studies. The properties utilized in coal petrologic studies are related to texture (size, form, and association), hardness, light reflectance, and light absorption and transmission (color). Size relations are most evident but are commonly overlooked. Coal is classed chemically as a mixture, and chemical analyses thus show the composition of the sample as a whole. Geologically coal is an organic clastic deposit, derived from diverse plant fragments and particles having a size range comparable to that of a conglomerate or breccia. The mixture of different materials that compose coal, large and small, can be realized only by microscopic study. This is because the fundamental cellular units of plants, from which coal is formed, are microscopic in size. The kinds of altered plant particles and fragments in coal have specific differences in hardness, reflectance, and color that signify differences in composition. These differences must be taken into account in evaluating the aggregate properties of coal. Terminology and Texture Full discussion of terms applied by various petro-logists in analysis of coal is beyond the scope of this article. For convenience the simpler types of petrologic entities that are defined without reference to lithologic occurrence or texture will be called coal components. Fig. 1 lists reactive and relatively inert

Jan 1, 1957

By Edward B. Walker, Michel Grosmangin

The geological and economic conditions peculiar to the Greater Oficina area are presented to demonstrate the necessity of a low-cost, well-site method of distinguishing gas-bearing formations. The method of gas detection with the neutron log is briefly discussed and its limitations are explained. A new method is described which consists in running a second neutron log with a larger source-to-detector spacing. Field data indicate that under favorable conditions the larger spacing response is proportionately more influenced by the virgin gas zone than is the shorter spacing response. One important condition is that the gas sands be invaded, with a diameter of invasion equal to about two to three times the hole diameter. The calibration of the longer spacing log is made so that the two logs read the same deflection in shale and in a known water or oil sand. Under such conditions, gas is indicated by a positive separation, i.e., the curve for the longer device is displaced to the right of the curve for the shorter device. Because of the non-linearity of the long spacing response, low porosity formations also show positive separations. In sands with large porosity variations, the gas sands can no longer he located visually. They can be detected on a plot of shorter spacing vs longer spac-ing deflections. INTRODUCTION In the Greater Oficina area of Eastern Venezuela, the rapid and accurate detection of gas from well logs is of primary importance because of a combination of economic, geologic, and operational conditions. Briefly, these conditions are: economic—there is no market for gas at the present time; geologic—a single well may contain as many as 30 or more oil or gas sands for which intervals -to be tested must be selected; opera-tional—first, once opened to the casing through perforations, gas sands are extremely difficult and expensive to squeeze off, and second, gas detection must be rapid because the geologist must decide immediately, at the well, which sand to perforate. During the early period of exploitation in Greater Ofi-cina, when clay base muds were used, sidewall samples, together with electric logs, gave fairly good distinction between oil and gas sands. When exploitation became concentrated on deep fields of poorer sidewall sample recovery, and after the advent of oil emulsion muds, now the standard drilling fluid in Greater Oficina, the regular neutron log became the most reliable indicator of gas. In 1953, R. Norelius devised the dual-spacing neutron technique for gas detection. The dual-spacing neutron log has proved to be highly successful in detecting gas and has been adopted as a regular survey by all of the oil companies of the area. Several hundred dual-spacing neutron logs have been run in Eastern Venezuela and several tests per well are available for positive evaluation of the logs. The findings outlined below are based upon this extensive field experience. GEOLOGICAL CONDITIONS OF THE GREATER OFICINA AREA The Greater Oficina area lies on the south flank of the Eastern Venezuela Basin (Fig. 1). Nearly all accumulations of oil and gas in the area are trapped, in whole or in part, against normal faults. All known oil and gas reservoirs in Greater Oficina occur in the Ofi-cina formation (Miocene-Oligocene) or in the "U" sands. The U sands are the lithologic equivalent of the Merecure group (Otigocene-Eocene), which contains oil in many fields north of Greater Oficina. Most of the petroleum produced in Eastern Venezuela is from the Oficina formation.

Jan 1, 1958

By L. Ekstrom, J. P. Dismukes

The homogeneity and microstrcture of zone-leveled Ge-Si alloys haw been investigated by sellera1 physical techniques and by metallography as a function of growth rate in the range 3 x 10 1x10 cm-sec', and as a system of alloy composition throughout the system. The temperature gradient at the solid-liquid interface was about 50 deg-cm-' Cellular or dendritic structures char-acteristic of constitutional supercooling were ob-served except at very slow growth rates, which ranged from about 2 x 10 cm -sec for Ge 1 sio alloy to about 2 X 10'5 cm-sec'1 for Ge .sSio.s alloy. Using a simple model similiar to that employed for dilute solid the dependence upon compo-sition over the entire system of the critical growth rate for the onset of constiutional supercooling was calculated, and was .found to he in good agreement with the experimental results. THE recent discovery of the low thermal conductivity of Ge-Si alloys' at high temperatures has revealed that these alloys have high efficiencies for thermoelectric-power generation.', Therefore, a reliable method was needed for the preparation of homogeneous samples required for definitive measurements throughout this alloy system. Due to the low diffusion rates in the solid alloys, the segregated samples obtained by quenching a melt are not readily homogenized by annealing.475 However. isothermal solidification from a melt of constant composition can produce uniform material. Of the available semiconductor crystal-growth procedures, the zone-leveling technique6 applied to a complete solid-solution alloy system by Wang and Alexander' and by others provides a simple method of doing this. In the present work, the homogeneity and microstructure of zone-leveled alloys have been correlated with growth conditions, and the conditions for preparing homogeneous Ge-Si alloys have been established. This has provided insight into the solidification process of alloy semiconductors. EXPERIMENTAL PROCEDURE Sample Preparation. The Ge-Si alloy phase diagram4 shown in Fig. l(a) consists of a complete series of solid solutions. The zone-leveling technique used to prepare most of the samples consists of moving a zone of liquidus composition (C1) through charge material of the corresponding solidus composition (C,), as is illustrated in Figs. l(b) and l(c). To prepare the charge materials, high-purity germanium and silicon were pulverized in a steel hammer mill, cleaned magnetically, and melted together to make uniform chill castings. The zone leveling was carried out in a resistance-heated furnace similar to that of Mitrenin et al.' shown in Fig. 2. However, a few specimens of high silicon content were prepared by the Czochralski technique. The growth rate ranged from 3.5 x X6 to 1.2 X 10~3 cm-sec-'. Temperature gradients in the solid and in the melt were determined by recording the temperature as the molten zone passed over a Pt-Pt 13 pct Rh thermocouple contained in a small

Jan 1, 1965

By T. R. Ingraham

The thermal decomposition of Nickel (II) sulfate was examined by determining the total pressure of SO3, SO2, and O2 developed over a sample when it was heated in an evacuated system fitted with a Pyrex-bellows mercury manometer. The equilibrium pressures were combined with previously published data on the oxide and sulfide systems to establish a predominance volume diagranz for the Ni-S-O system over the normal range of roasting temperature and gas composition used in the treatment of nickel minerals. The protective coating of NiSO4 which forms on the oxide during roasting, and which causes the sulfation reaction to almost cease, may be disengaged readily by temperature cycling. When nickel sulfide is roasted in air, either nickel sulfate or nickel oxide may be formed by altering the experimental conditions. Because of the differing stabilities of various metal sulfates and oxides, possibilities exist for separating some of the constituents of mineral mixtures by the technique of selective sulfation and oxidation roasting. The experimental information required to make reasonable predictions of the possibilities of this technique is incomplete and, in some cases, in conflict. As part of a general program of providing some of the required information, a study EXPERIMENTAL Materials, Apparatus, and Procedure. Fisher certified reagent-grade nickel sulfate hexahydrate was used in the source material for both nickel sulfate and nickel oxide. The manufacturer's analysis indicated: 0.001 pct Fe, 0.005 pct Cu, 0.003 pct Co, 0.001 pct C1, other 0.15 pct. The material was dehydrated, before use, by heating at 420°C for 5 hr. The oxide was prepared by roasting the sulfate in an open tray in a muffle furnace for 10 hr at950°C. Preliminary experiments which were made by thermogravimetric analysis and X-ray diffraction analysis established that only one crystal form of nickel oxide and one of nickel sulfate were involved in the equilibrium shown in Eq. [I]. The apparatus used in the experiments was described previously.1,3 The main feature is a corrosion-resistant, flexible Pyrex bellows which is used to protect the mercury in a u-tube manometer. Before a run was begun, the apparatus was washed thoroughly with hot hydrochloric acid and water and dried by heating under vacuum. The mixed sulfate -oxide sample was contained in a platinum bat rest-

Jan 1, 1967

By J. Mackintosh Bell

The history of the South Lorrain mining camp is given and comparisons are made between the local topography and general geology and that of the Cobalt camp. The character of the silver-bearing veins and their analogy to those of Cobalt are given and the theory regarding the cause of the deep seated oxidation in South Lorrain, particularly at the Keeley Mine, is outlined. The oreshoots are described, also the conditions governing their occurrence and position. The mining and metallurgical practice are briefly considered. IN THE numerous districts subsidiary to Cobalt, and carrying mineral deposits similar in character to that world-famous mining camp, the most interesting recent developments have occurred in South Lorrain. The district, the center of which lies about 16 miles southeast of Cobalt, was the scene of a rush in 1907 but, in spite of the success of the Wettlauffer mine, the locality soon lost its popularity, largely on account of the unsavory early history of the Keeley mine. In recent years, following the successful development of this property by the London operators, who acquired it from the liquidator of the original company, and the later conspicuous progress made on the properties of the Mining Corporation contiguous to the Keeley on the north, the district has again come into prominence and, at present, is doing much toward maintaining the gradually declining production of Cobalt itself. Apart from the Mining Corporation of Canada and the Keeley Silver Mines Limited, the principal concerns now operating in South Lorrain are the Lorrain Consolidated, the Trout Lake Mines (operated by English interests associated with the Mining Corporation) and the Canadian Lorrain Silver Mines (operated by the Huronian Belt Co., of London). A number of minor prospects are also active. The Wettlaufer and Currie, on both of which considerable work was done some years ago, are now closed.

Jan 1, 1924

By W. A. Wood, W. H. Reimann

A study is made of the creep that can be induced in armco iron at room temperature by superposing small amplitudes of alternating torsion on a tensile creep load. It is shown that the creep differs from that in comparable tests on copper in being trmsient only. At the same time, though transient, the creep can produce extensions of some 10 pct under creep loads less than the tensile yield stress of the material. The creep can be largely suppressed b$ applying cyclic strain of suitable amplitude before applying the creep load and the metal thereby stabilized. At room temperature, plastic flow in a metal under steady load is normally limited by strain-hardening processes. However, if a small cyclic stress is superposed on the steady load these processes may be more or less neutralized and, as shown in recent investigations,'-4 plastic flow may continue. In this way annealed copper, for example, can be induced to creep continuously to fracture under loads as small as 1 tsi. Dislocation mechanisms possibly responsible for this room-temperature creep have been usefully reviewed by Feltner.But discussion so far has been based mainly on creep as it is found in close-packed metals initially in the annealed state, and their behavior may not be general. In fact, recent work shows that the form of creep in annealed copper is different from that even in cold-worked copper;7 the creep thus depends on the dislocation pattern already in a metal as well as on the metal itself. This paper describes the creep in annealed armco iron, tested in the same way as the above-mentioned copper. One object was to see how creep in a typical bcc metal compared with that in the annealed close-packed metals. Another object was to utilize the fact that a bcc metal like iron has a more pronounced elastic range than close-packed metals like copper and to find to what extent the creep load or superposed cyclic stress had to exceed their re-

Jan 1, 1964

By Charles Barrett

METALLURGISTS are making use of the stereographic projection to a steadily increasing extent. In the last five years no less than 20 papers in American metallurgical journals alone have employed the stereographic projection; recent books on physical metallurgy, plastic deformation, X-rays and their applications, and crystal structure use it. Mineralogists have used the stereographic projection for many years in the description of symmetry classes and crystal planes, for it presents an accurate, easily understood plot of any angular relations in crystals with all unessential features eliminated (such as the accidentally deter-mined size and shape of crystal faces). In metallography and physical metallurgy the projection is much used for the analysis of markings appearing on polished grains: slip lines, twins, cracks, structures formed by precipitation, magnetic-powder patterns, etch pits, etc. Data from certain types of X-ray photograms are most conveniently analyzed by its use, particularly those for determining the orientation of single crystals or the preferred orientation of grains in an aggregate. Calculations of how to tilt or cut a crystal parallel to a certain crystallographic plane or to reflect X-rays from a certain plane are rapidly carried out. It has been adopted almost universally to the exclusion of other methods by those studying the deformation of metallic crystals, save where the accu-racy required is greater than a few tenths of a degree. Any directional property in a crystal or polycrystalline material can be shown on a stereo-graphic projection; for example, the modulus of elasticity, yield point, etc. It has been repeatedly called to our attention that there is need of all elementary explanation of the principles and methods of stereographic projection, covering all the, common applications in the field of metal-lography and physical metallurgy. The following contribution is an attempt to fill this need. The description of each method is supplemented with references to publications in which the method has been used. For convenience to the reader, these illustrative references are chiefly in American journals, particularly the publications of the American Institute of Mining and

Jan 1, 1937