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By W. Hurst

What is entailed here is the extension of the sinzplified material balance formulas to encompass interference between oil fields. As previously reported, the ex-plicitness as so revealed for the cunzulative pressure drop as a function of all factors contributing to its change in the material balance equation, is now transcribed through the inter-conzmunicating aquifer to effect an increased pressure drop on an adjoining field by interference. Such is performed by mathematical analyses and the application of the Laplace transformations. What is accomplished is that the reiteration problems previously associated with interference studies are nullified, since volumetric changes for the fluids in situ are automatically adjusted by the explicitness so expressed, and what pertains to the superposition principle applies only to the impeded water drive upon a su.bject field, which is likewise incorporated in the over-all pressure drop that results. The mathematics treats with the rigorous solution of the problem, as well as with methods easily amenable to numerical interpretation by the practicing engineer. In all cases, however, what is deduced for areal extents, reveal interference between wells when time becomes large that further substantiate the analyses. Probably of equal significance, all variables and for/nation characteristics are accounted for. This applies to the differences in PVT analyses that occur from field to field and the physical parameters associated with the lithology of the reservoirs. The latter is deduced from a rigorous interpretation of the unsteady-state flow problem for sands of different permeabilities in series. Thus, what purports to be a trial-and-error calculation to include variations in sand conditions within the intercommunicating aquifer to define water drive has little importance compared to the designation of such paranzeters at the reservoir to constitute the essential criteria. INTRODUCTION In a recent publication, the reader has been introduced to the simplified material balance formulas,' It has been shown that the complexities formerly associated for identifying and determining reservoir pressure in the material balance relationship can be resolved by treating with the Laplace transformations, the inversion of which reveals pressure as an explicit function of all factors contributing to its change. For an under saturated oil reservoir, this constitutes an integrated effect from the inception of production; and for a saturated oil reservoir, such represents a survey traverse. However, what is most important, for the first time we are able to express the pressure change in a reservoir directly to the oil, gas and water produced, and to the physical parameters of the formation, in the same manner that reservoir pressure has served in the past to define well interference — which opens up this avenue of endeavor for investigating interference between oil fields. The occurrence of interference is by virtue of the juxtaposition of two or more oil reservoirs producing in the same aquifer. Thus, in any one field, the extended production so incurred creates a pressure lowering in the field, as well as in the aquifer, which can now be transcribed by these simplified material balance formulas to the adjoining reservoir to observe the increased pressure change so induced. These effects are retroactive from field to field, to reveal a pressure drop far in excess of normal depletion to evidence the interference pattern that can result. Such is the purpose for the present undertaking — to develop the mathematical physics treating with this phenomenon of interference between oil fields, employing the simplified material balance formulas. Since Ref. 1 often will be referred to in the text, it is identified as "The Simplification", in the same connotation that another paper has been referred to as the "Laplace Trans-formation. However, the amount of material to be covered in these passages is substantial; therefore, the total emphasis will be placed upon developing these fundamental ideas treating with interference rather than attempting to offer work curves, which always can be prepared. For the practical application of these simplified material balance formulas that form the framework of the present development, the reader will find a comprehensive treatment in the Appendix of Ref. 1, illustrating a factual field example. In essence, what is proposed by this presentation is to make available to the practicing engineer a simplified means to treat with interference between oil fields, independent of the complex machine computations that have attended such undertakings in the past. As the problem unfolds, a common pattern will be discernible, whereby the many reiteration processes that previously required computing devices are eliminated.

By C. F. Cigliana

TO accommodate a large tonnage at high speed from a single level at San Manuel, a very flexible haulage system was designed to give maximum access to stoping areas, minimize delays, and pro- vide for safety. With these requirements as a guide, the haulage was laid out as a simple double loop with one-way traffic of continuous pull. These loops consist of two parallel drifts 100 ft apart, center to center. Haulage drifts are numbered from north to south, the northernmost being the No. 1 drift. This holds true on both the North and South haulage loops. Haulage drifts are connected at 1000-ft intervals with crossovers so that it is possible to bypass any given section that may be inaccessible. Two of these turnouts are double diamonds, one located on the approach to the rotary dumps at the hoisting shafts and the other on the departure from the dumps. The turnout on the approach or North haulage is 835 ft in front of the rotary dump, and the one on the departure, or South haulage, is 1058 ft from the dump. This type of turnout allows trains coming down either haulage drift No. 1 or No. 2 to be routed into either shaft and expedites movement by avoiding delays due to congestion in the dumping area. The double diamond on the return haulage loop facilitates returning empty ore trains to the panels.

Jan 5, 1958

By H. H. Hausner, O. V. Roman, F. V. Lenel, G. S. Ansell

The radial shrinkage during sintering of cylindrical compacts and loose aggregates of copper powder was measured. It was found to be nonuni-form from top to bottom of the samples and to depend upon the method of supporting them. The non-uniformity is due to the effect of gravity forces during sintering. Since gravity has an effect in sintering without externally applied stresses, no sharp dividing line can be drawn between conventional sintering and hot pressing. RECENT investigations of the sintering behavior of compacts1 and of loose powder aggregates2 have indicated that forces, other than those arising from surface tension effects, may play a role in shrinkage. In compacts it was shown that residual stresses from the pressing operation influence shrinkage behavior. In loose powder aggregates gravity forces due to the weight of the powder affect the ratio of shrinkage in the vertical and the horizontal direction. The main effort in the work reported here was to show that gravity plays a role also in the sintering of compacts. A few additional experiments were made confirming the effect of gravity in the sintering of loose powder aggregates. EXPERIMENTAL PROCEDURE Compacts and loose powder aggregates were prepared from irregularly shaped, electrolytic copper powder. Prior to use the powders were reduced 30 min at 400°C in dry hydrogen to remove surface oxides. Then the -325 mesh size fraction was separated from the -100 + 325 mesh fraction. The compacts were pressed at a pressure of 10,000 psi from 50 g of powder in a hardened steel die, 1 in. in diam. The height of the compacts was 0.725 i 0.005 in. An effort was made to get as uniform a green density distribution in the compacts as possible. The walls of the die were lubricated with a suspension of 3 pct of zinc stearate in acetone and the compacts were pressed using double action by first pressing the powder at 1200 psi with the die barrel supported, then removing the sup- ports and pressing to final pressure of 10,000 psi with the die barrel floating. The pressure was maintained for 10 sec. The compacts were sintered at a temperature of 925°C, generally for 1 hr. In order to maintain uniform temperature they were sintered in boats made from cylindrical copper blocks. The blocks were 2 in. in diam, either 2 or 2 1/2 in. long and, split to form the body of the boat and a lid. The body of the boat contained a cavity 1 3/8 in. wide, 1 in. deep and either 2 1/8 or 1 3/8 in. long. The longer cavity accomodated two samples, the shorter one only one sample. The uniformity of temperature distribution within the boats was checked with thermocouples welded to the top and bottom of the samples. The maximum variation between top and bottom temperatures was i 1/2°C. The actual sintering temperature was held constant within ±2°C. In order to determine the effect of gravity forces, i.e., the weight of the compacts, upon shrinkage, they were supported in the following ways during sintering: a) Full Bottom Support. The compacts rested either on a flat alundum disk or on alundum powders. b) Partial Bottom Support. The compacts rested on a graphite cylinder, 0.3 in. in diam which formed a projection on a larger graphite disk. It is difficult to balance the compact on the small projection. To avoid having the compact tip, a small hole was drilled through the compact and through the graphite disk and its projection. The graphite disk was then suspended from the lid of the boat by a thin iron wire which passed through the holes in the disk and the compact. c) Top Support, first type. A hole 3/32 in. in diam was drilled diametrically through the green compact 3/16 in. from the top of the compact. The compact was sintered suspended from an alundum rod (thermocouple protection sleeve) inserted into the hole. d) Top Support, second type. A hole was drilled axially through the center of the compact. The upper part of the hole from the top surface of the compact one fourth of the way down was 1/16 in. in diam; the lower part of the hole from the bottom surface three fourth of the way up was 3/32 in. in diam. The compact was suspended from the lid of the boat by an iron wire passing through the upper part of the hole and then tied into a knot. The loose powder aggregates were made by filling l in. deep, l in. diam cylindrical graphite molds with -325 mesh powder. To achieve uniform density in all the loose powder aggregates, the powders were settled in the molds by placing the

Jan 1, 1963

By F. H. Kihlstedt

The Larap iron deposits, 125 miles east of Manila, are the biggest high-grade iron deposits in the Philippines, and have in seven years produced nearly 4 million tons of 60 per cent ore. Magnetic surveying followed by churn and diamond drilling cheaply developed a score of million tons. The ore zone is a wedge of metamorphic rocks in fresh, Miocene sediments overlain by agglomerates, which seem to have filled a river valley eroded in the sediments. A mild overthrust of the competent agglomerates crumbled the shale in front. Solutions gradually turned it into more competent hornfels and deposited pyrite, then magnetite and pyrite in the pores. As the temperature rose large bodies of magnetite with some pyrite were deposited by replacement and in open cavities in tensional areas of overthrust shears. At still higher temperature magnetite and calcium-magnesium silicates formed other bodies in similar cavities, and finally the thrust zone was invaded by syenite porphyry, causing high-temperature alteration products. Possibly, as temperature abated, more high-grade ore was deposited. The complicated faulting indicates dynamic, chronological and spatial changes of mineralization rather than zoning in a static system. Noncommercial copper, molybdenum and some gold accompanied the iron mineralization. In the thirties the Philippines gained a justified reputation as a country of considerable mineral wealth. Traces of Chinese workings show that these earliest travelers and traders had in a small way exploited the latent gold resources in the Islands. The Spaniards continued this for centuries, but did not succeed in establishing any steady mining industry. Modern technology was required to get it started. The rapid development in the last decade before the war got its impetus from several financial factors, the return to sugar growers of previously collected taxes, the influx of Spanish capital during the civil war in Spain, the influx of Chinese capital when the Japanese started their "China incident," and others. Directly or indirectly much of this capital reached the mining industry; in particular, gold mining. Out of the turmoil of an exceptional mining boom emerged a sufficient number of good and well managed gold properties to send the production to a level above that of any single state in the United States at the time. Other ore deposits besides those of gold also received their share, and for a country without any heavy industries at

Jan 1, 1949

By F. H. Kihlstedt

The Larap iron deposits, 125 miles east of Manila, are the biggest high-grade iron deposits in the Philippines, and have in seven years produced nearly 4 million tons of 60 per cent ore. Magnetic surveying followed by churn and diamond drilling cheaply developed a score of million tons. The ore zone is a wedge of metamorphic rocks in fresh, Miocene sediments overlain by agglomerates, which seem to have filled a river valley eroded in the sediments. A mild overthrust of the competent agglomerates crumbled the shale in front. Solutions gradually turned it into more competent hornfels and deposited pyrite, then magnetite and pyrite in the pores. As the temperature rose large bodies of magnetite with some pyrite were deposited by replacement and in open cavities in tensional areas of overthrust shears. At still higher temperature magnetite and calcium-magnesium silicates formed other bodies in similar cavities, and finally the thrust zone was invaded by syenite porphyry, causing high-temperature alteration products. Possibly, as temperature abated, more high-grade ore was deposited. The complicated faulting indicates dynamic, chronological and spatial changes of mineralization rather than zoning in a static system. Noncommercial copper, molybdenum and some gold accompanied the iron mineralization. In the thirties the Philippines gained a justified reputation as a country of considerable mineral wealth. Traces of Chinese workings show that these earliest travelers and traders had in a small way exploited the latent gold resources in the Islands. The Spaniards continued this for centuries, but did not succeed in establishing any steady mining industry. Modern technology was required to get it started. The rapid development in the last decade before the war got its impetus from several financial factors, the return to sugar growers of previously collected taxes, the influx of Spanish capital during the civil war in Spain, the influx of Chinese capital when the Japanese started their "China incident," and others. Directly or indirectly much of this capital reached the mining industry; in particular, gold mining. Out of the turmoil of an exceptional mining boom emerged a sufficient number of good and well managed gold properties to send the production to a level above that of any single state in the United States at the time. Other ore deposits besides those of gold also received their share, and for a country without any heavy industries at

Jan 1, 1949

By V. Koump, R. H. Tien, W. J. Kim

This paper presents an approximate solution of the problem of freezing of a binary alloy. he alloy is in the form of a one-dimensional slab of finite thickness. The surface temperature of the slab is assumed to be constant and lower than the solidus (or eutectic) temperature. The densities of the liquid and the solid are assumed to be equal. For a given binary alloy system, initial concentration of solute and surface temperature, the solution yields a) the temperature distribution in the solid skin, b) the temperature, concentration, and solid fraction distribution within the solid-liquid region, and c) the positions of the liquidus and the solidus (or eutectic) fronts as a function of time. The results of calculation for Fe-C and Fe-P systems are presented. In this investigation we are considering the problem of solidification of a binary alloy. The alloy is in the form of a one-dimensional slab of finite thickness. The molten alloy is initially at liquidus temperature. At time zero the surface of the slab is reduced to a temperature T, < Te,, where Te, is the solidus (or eutectic) temperature and T, is a constant. The densities of solid and liquid alloys are assumed to be equal and independent of temperature and composition. A qualitative picture of solidification of an alloy, under these conditions, is illustrated in Fig. 1. During the initial stage of solidification, before liquidus front reaches the center of the slab, freezing proceeds by propagation of two isothermal fronts, the liquidus front and the solidus (or eutectic) front. The fraction of solid at the liquidus front is zero; the fraction of solid at the solidus front is unity, The solid fraction and the temperature distribution between the two fronts and the width of the solid-liquid region change with time. During the later stage of freezing, after the liquidus front reaches the center of the slab, the liquidus front disappears. The solid fraction and the temperature at the center of the slab, as well as throughout the solid-liquid region, are now changing with time. The solidification is completed when the fraction of solid at the center of the slab reaches unity. In solution of this problem we seek to determine a) the temperature distribution in the solid, b) temperature, concentration,

Jan 1, 1968

By James Norman, E. W. Gieseke

Spodumene is a lithium-bearing pyroxene, and is an important source of lithium compounds. Because of its high alumina and lithia content, it might be a desirable constituent of glass batches. The use of spodumene in ceramics will undoubtedly increase, as it has been shown that a mixture of the proper proportions of this mineral with soda feldspar and potash feldspar has a much lower maturing temperature upon firing than has any one of the three components. The mineral spodumene seldom occurs as pure mineral, but ordinarily with feldspars, mica and quartz. All spodumene-bearing rocks tested contained these minerals as gangue. Small amounts of iron and manganese oxides also were present, usually as stains on the silicate grains. Mica associated with the spodumene carried a considerable amount of lithia. This was discovered in flotation tailings, which, although virtually free of spodumene grains when examined microscopically, showed 0.4 to 0.5 per cent Li²O on chemical analysis. The lithia content of micas picked from the North Carolina spodumene rock was variable. Some samples contained little lithia, others more than 3 per cent. In 1938, under the supervision of Oliver C. Ralston,S the Bureau of Mines, in cooperation with the Tennessee Mineral Products Corporation, undertook to study the beneficiation of North Carolina spodumene by froth flotation. The Bureau had previously published investigations on the beneficiation of spodumene.2,3The methods described in the second publication3 did not give good results with badly weathered spodumene rock, so that more thorough investigation of the subject was warranted. Study of Method of Flotation Separation Most of the work on concentration of spodumene was done with rock from near King&apos;s Mountain, North Carolina. Rock from two

Jan 1, 1942

By James Norman, E. W. Gieseke

Spodumene is a lithium-bearing pyroxene, and is an important source of lithium compounds. Because of its high alumina and lithia content, it might be a desirable constituent of glass batches. The use of spodumene in ceramics will undoubtedly increase, as it has been shown that a mixture of the proper proportions of this mineral with soda feldspar and potash feldspar has a much lower maturing temperature upon firing than has any one of the three components. The mineral spodumene seldom occurs as pure mineral, but ordinarily with feldspars, mica and quartz. All spodumene-bearing rocks tested contained these minerals as gangue. Small amounts of iron and manganese oxides also were present, usually as stains on the silicate grains. Mica associated with the spodumene carried a considerable amount of lithia. This was discovered in flotation tailings, which, although virtually free of spodumene grains when examined microscopically, showed 0.4 to 0.5 per cent Li²O on chemical analysis. The lithia content of micas picked from the North Carolina spodumene rock was variable. Some samples contained little lithia, others more than 3 per cent. In 1938, under the supervision of Oliver C. Ralston,S the Bureau of Mines, in cooperation with the Tennessee Mineral Products Corporation, undertook to study the beneficiation of North Carolina spodumene by froth flotation. The Bureau had previously published investigations on the beneficiation of spodumene.2,3The methods described in the second publication3 did not give good results with badly weathered spodumene rock, so that more thorough investigation of the subject was warranted. Study of Method of Flotation Separation Most of the work on concentration of spodumene was done with rock from near King&apos;s Mountain, North Carolina. Rock from two

Jan 1, 1942

By M. J. Sheriff, D. H. Smith, W. Macdonald

The paper outlines the basic procedure used in electrical system planning and design. Consideration is given to the use of applicable codes and standards, development and use of a system One Line Diagram, power availability, load requirements and power factor. Also discussed are the factors influencing the selection of power supply and distribution arrangement, voltage levels, system grounding, distribution and utilization equipment such as switchgear, transformers, motor control, cable systems, motors. Short circuit calculation methods and system protection are discussed.

Jan 1, 1978

By F. E. Bachman

Although it has been apparent to me for a long time that too great weight was currently given to the silicon-contents of foundry-iron, and that the theory of the control by silicon of the carbon-contents of cast-iron is unsound, or that, at best, the influence of silicon is too small to be of much practical value as a guide in foundry-work, it never seemed to me desirable to enter the lists against either the " silicon-fad " or the theory, for the reason that I had neither the time nor the facilities to prove my position, nor any better theory to offer. But since Mr. Summers has taken the step, it seems but right that I should give such facts as are at hand in support of his contention. At the same time I do not think these are enough to prove the case if the contrary proposition were not itself, as it seems to me, based on insufficient evidence. Both Keep&apos;s and Turner&apos;s conclusions seem to be drawn from irons carrying less than the normal amount of carbon; Turner&apos;s " base " being, moreover, a steel rather than a pig-iron, and both the white base and the ferro-silicon of Keep being so low in carbon that compounds of them would not give a material approaching the carbon-contents of a normal casting, and having, therefore, little value as showing the effects of silicon on foundry-irons, even if his samples were treated under the same conditions as those to which pig-metal is subjected in making castings.

Jan 1, 1899

By Robert E. Green, Edmund G. Henneke

The velocities of the three possible modes of elastic wave propagation have been calculated for single-crystal copper at 1-deg intervals throughout the standard stereographic triangle. The results are presented as isospeed contours. The deviations between the direction of maximum energy flux and specimen axes are presented as arrows drawn on stereographic projections. The orientation factors associated with dislocation motion on the primary slip system only and also on all twelve slip systems have been calculated for all three elastic waves. The orientation factors associated with a longitudinal standing wave resonant specimen have also been calculated. The results of these calculatians are compared with earlier calculations on aluminum crystals and the relevance of these results to ultrasonic attenuation measurements is discussed. GREEN and inton&apos; have recently outlined a procedure for determining the orientation factors for dislocation damping in single crystals. The stress field associated with a given mode of elastic wave propagation is resolved on the slip systems in which it is assumed the dislocations are vibrating due to this stress field. Since, at room temperature, slip has been observed on a limited number of systems in fcc and hcp metal crystals, it is assumed that these systems are the appropriate ones to use for the resolving process. This procedure has been applied to aluminum crystals by Hinton and hreen&apos; and to zinc crystals by Henneke and Green.3 In the present paper the modes of elastic wave propagation have been calculated for copper crystals possessing orientations at 1-deg intervals throughout the standard stereographic triangle. The deviation of the energy flux vectors from the specimen axis have been calculated for each mode. The stress field associated with each mode has been resolved on the (111)(110) slip systems in order to determine the orientation factors for dislocation damping. MODES OF ELASTIC WAVE PROPAGATION For any direction in a linear homogeneous aniso-tropic material three elastic modes can be propagated. In general, each of these modes has both longitudinal and transverse particle displacements associated with it and thus are not "pure" modes. However, there is always one component which is greatest in either a longitudinal or transverse direction and hence the mode may be referred to as quasi-longitudinal or quasi-transverse, accordingly. For certain axes of high symmetry pure modes may be propagated. The phenomenon of refraction of the energy flux vector is also exhibited by elastic wave propagation in ani-

Jan 1, 1969

By J. H. Westbrook

UNTIL very recently the development of high temperature alloys has been strictly empirical. It is, in fact, a great tribute to the intuition, perseverance, and industry of the practicing metallurgists of this country and abroad that the amazing increases in gas turbine service temperature over the past 15 years have been achieved with so little fundamental knowledge. The result of this development has been the realization of successful but highly complex alloys possessing five, six, or more alloying elements and correspondingly complex microstructures. Within the last few years, considerable effort has been devoted to the identification of the secondary phases in these alloys and to the correlation of the presence or absence of such phases with alloy properties. Little attention, however, has been given the problem of identification of the mechanism (s) by which such phases enhance the properties of the alloy and especially to the assessment of the particular properties of the secondary phase (either in- trinsic or relative to the matrix phase) which are basically responsible for the improvement. Conceivable mechanisms which might apply include dispersion hardening and precipitation hardening. In both cases geometrical factors—particle size, dispersion, volume fraction, etc.—and agglomeration re-

Jan 1, 1958

By E. Posnjak

IT is rather the general belief that acidified solutions of ferrous salts are readily oxidized when in contact with air, and often elaborate pre-cautions are taken to prevent it. This, however, is not the case and several statements may be found in the literature expressing surprise at the extreme slowness with which oxidation takes place when air or oxygen is bubbled through such a solution. Thus C. Baskerville and R. Stevenson1 "observed with surprise" that no. oxidation apparently took place, as shown by titration with 0.5 N KMnO4, when a stream of air was passed for 3 hr. through an acidified solution of ferrous ammonium sulfate or ferrous sulfate. The same authors state that even the presence of salts such as cobalt, chromium, copper, manganese, etc., which usually act as oxygen carriers, had "no effect upon the oxidation as was observed by, passing air for 3 hr. through solutions of Mohr&apos;s salt acidified with sulfuric acid." While this statement will be proved further on to be at least partly incorrect the slowness of the oxidation of ferrous salts alone has been previously established by McBain.2. His investigation also showed that the rate of oxidation increases markedly with an increase in the concentration of ferrous sulfate as well as that of oxygen; the concentration of free acid had a comparatively small influence, which in the case of sulfuric acid was to retard slightly the rate of reaction. More recently R. Thomas and E. T. Williams3 investigated the catalytic effect of nitric oxide on the oxidation of ferrous salts, which had been earlier patented by McCulloch.4 They found that the probable mechanism of the catalytic action was the oscillation of the catalyst between two stages of oxidation and its interaction alternately with the oxygen and the ferrous iron.

Jan 1, 1927

By B. Habermann

Artificially consolidated sand models, representing one-quarter of a five-spot, have been developed and used to study factors aflecting misciblt. displacrmenr. Sweep efficiency at breakthrough, size of the mixing zone between two miscible liquids and per cent area contacted by drive after breakthrough were determined tor the high mobility ratios encountered in actual resvrvoirs. Quantitative relationships between the degree of viscous fingering and mobility ratio were obtained by measuring the length of the fluid interface. Scaled miscible-slug experiments, supported by field evidence reported in the literature, have shown that when the slug is followed by dry gas the process is less efficient than expected. In addition to low areal sweep efficiencies encountered for high mobility ratio displacements, the effectiveness of a miscible slug is greatly reduced. This is caused by an accelerated growth of the mixing zone between the driving and the displacing fluids. INTRODUCTION Considerable interest in miscible displacement as a secondary recovery process has been shown by the oil industry in recent years. In addition to extensive laboratory investigations, numerous field operations have been initiated so that 39 miscible displacement projects had been reported&apos; in the United States by early 1959. By far the most popular approach in these projects is the use of an LPG slug followed by dry gas. Laboratory tests have indicated that with a small miscible slug, amounting to several per cent of the hydrocarbon pore volume, practically 100 per cent recovery of the oil in place can be achieved and that all of the slug material can be recovered by a subsequellt gas drive. However, these experiments were conducted on small-diameter long cores that can be considered as essentially uni-dimensional reservoirs that do not represent actual field conditions. It soon became apparent that the inherently adverse mobility ratios existing in the reservoir cannot be ignored in any miscible displacement field project. When a less viscous fiuid such as an LPG slug drives a more viscous reservoir oil, fingers develop that reduce the areal sweep efficiency. The slze of the miscible slug to be used is a subject of some controversy. It has been proposed that the size of siug needed be calculated by setting lengths of the mixing zone proportional to the square root of the distance traveled. This proposal is based on experimental evidence&apos; and theoretical considerations"&apos; in which fingering was not a factor. A prerequisite for successful application of the miscible displacement process to field operations is a better understanding of the following factors. L What is the effect of mobility ratio on the rate of deterioration of a miscible slug? 2. How large a slug should be used for given reservoir conditions? 3. What is the sweep efficiency? The purpose of this investigation was to provide some additional laboratory data that should help to answer these questions. More specifically, it was intended to study more quantitatively the effect of viscous fiinger-ing, mobility ratio and slug size on the efficiency of this relatively new secondary recovery process by means of experiments on thin, horizontal, porous medium models.

By B. H. Caudle, M. D. Witte

In predicting the performance of a pattern injection operation, the engineer needs to know both the amount of oil to be recovered and the rate at which the recovcry will take place. This paper- describes fluid flow model studies on the effect of mobility ratio on the rate of oil recovery in a five-spot. The results show the change in fluid conductivity (total flow rate/pressure drop) as the sweep-ont pattern increases for mobility ratios between 0.1 (and 10. There data, when cornbitted with a knowledge of reservoir permeabilities and sweep-orit pattern efficiencies, cata he used to predict the cLrmulntivr oil production as a function of time for homogeneous five-spot injection systems. INTRODUCTION The flow potential in a pattern flood element is a function of the mobility ratio and how far the injected flood front has gone.1,2 For a waterflood project having a mobility ratio of one, the conductance—which is the flow rate per unit pressure drop (q/Ap)—-will remain the same throughout the life of the flood. If the mobility ratio is favorable ( < I), the conductance of the project will drop continuously throughout the operation. If, on the other hand, the mobility ratio is unfavorahlc. the conductance ratio will increase continuously. Therefore, if the reservoir engineer wishes to predict either the rate at a specified pressure or the pressure at some rate for a secondary recovery project, he must know how the conductance will vary during the flood. Other investigators have studied this problem using potentiometric models&apos; or analytical solution&apos;. The

By D. G. Russell

Two techniques have been developed with which the applicability of pressure build-up analyses can be extended to include pressure data which previously have been considered virtually unusable. One of the interpretation methods makes possible the analysis of pressure build-up performance during the wellbore fill-up or after production period which occurs soon after a well is closed in. The other technique is an extension of a method for analyzing pressure build-up performance during the late-time portion of the pressure build-up which occurs after boundary eflects first begin to alter the shape of a conventional pressure build-up curve. With both of these methods it is possible to obtain estitnates of the kh product, the skin factor and the reservoir pressure. In addition, with the late-time analysis technique it is possible to obtain an estimate of the contributory drainage volume of the well being tested. This means that in some cases a check on reservoir limit test and (or) material-balance calculations can now be obtained from pressure build-ups. Both methods are slightly more time-consuming than conventional pressure build-up analysis methods because trial-and-error plots of pressure data must be made. The late-time method for analysis of pressure build-ups is in principle applicable to the late-time portion of a two-rate flow test or a pressure drawdown test. The interpretation formulas and procedures for these types of tests are also outlined. In these cases, as with pressure build-ups, it is significant that an estimate of the contributory pore volume is also obtained. On the basis of limited experience with the new techniques, it appears that satisfactory estimates of the kh product, skin factor, reservoir pressure and, for late-time analysis, contributory drainage volume can be obtained. INTRODUCTION The analysis of bottom-hole pressure build-up behavior in closed-in wells has been a a subject of interest in petroleum engineering circles for many years. In fact, few other subjects have received as much attention as pressure buildup analysis methods have. The cause for this interest is essentially twofold in nature. First, the pressure behavior of a well can normally be measured with a reasonably high degree of accuracy so that good data for analysis can be obtained. Secondly, over a fairly wide range of operating conditions, valuable information as to the quality of the reservoir rock and completion efficiency of the well can be obtained at a nominal cost. In recent years, numerous papers have been prepared on the effects of various operating conditions and reservoir heterogeneities on pressure buildup behavior. Very little work has been done, however, on extension of pressure build-up analysis methods to those pressure data which are not amenable to analysis by the present methods. The theory upon which the analysis of shut-in bottom-hole pressure build-up data is based is derived from the solution of the radial flow equation for a slightly compressible fluid for constant-rate conditions. It requires that the well be closed in for a sufficient period of time to obtain a clearly defined linear portion on the plot of observed bottom-hole pressure vs log (t + ?t)/ ?t (where At is shut-in time, and t is producing time to the instant of shut-in). From the slope of the plot and other normally obtainable data, the formation permeability, the well damage or skin factor, and the reservoir pressure at infinite shut-in time (if the reservoir were infinite) can be estimated. The successful application of this procedure depends on being able to recognize the straight-line section on the basic pressure build-up plot. The presently used pressure build-up interpretation theory also assumes that a well is closed in at the sand face and that no production into the well occurs after shut-in. In practice, of course, the well is closed in at the surface, and inflow into the well continues until the well fills sufficiently to transmit the effect of closing-in to the formation. This adjustment period is commonly referred to as the "afterproduction" or "fill-up" portion of the pressure build-up. During the period that the well fill-up effect is most pronounced, the basic pressure build-up plot is nonlinear. At later shut-in times after the effects of a drainage boundary have been felt at the well, deviation from the straight-line behavior of the pressure build-up plot also results. In many cases either of these effects or a combination of both can make the straight-line portion on the pressure build-up plot difficult to recognize. Obviously, an extension of pressure build-up analysis methods to include the afterproduction period and the period in which boundary effects are being felt would be desirable and might render valuable pressure data which for years have been considered virtually unusable. The principal reference of note concerning pressure buildup analysis during the afterproduction period is a paper by Gladfelter, Tracy and Wilsey.1 In the approach of these authors it is necessary to measure the rate of influx into the well during the afterproduction period. This is done through sonic measurements or through measurement of tubing-head and casing-head pressures simultaneously with

Jan 1, 1967

By D. Hanson

Fox most of their practical applications metals are required to with-stand stresses of appreciable magnitude: indeed, it is because they possess the quality of resisting stress without becoming permanently deformed that they find such extensive use in the service of man. Metals and alloys must, in service, usually behave as elastic substances-or nearly so. It is not difficult to satisfy this condition at ordinary temperatures. Iron and its alloys, especially the steels, are at normal temperatures excellent elastic bodies, capable of satisfying most of the mechanical requirements of the engineer: where electrical, chemical or other properties are impor-tant, which cannot be met by steels, it is usually possible to find a non-ferrous alloy such as nickel, copper or aluminum, which will prove satisfactory. When the metals or alloys are not inherently sufficiently elastic, cold-working or heat-treatment may develop elastic properties to a sufficient extent for practical needs. By means of relatively simple, rapid tests we can measure such properties as elastic modulus, limit of proportionality and proof stress, upon which design can be based with confidence. The case of the soft metals, such as lead and tin, is well known to be exceptional. They possess no definite limit of elasticity, and the value of proof stress or tensile strength depends to a great extent on the speed with which the test is carried out. Design here must be based on other considerations than a well-established theory of the proportionality of stress and strain. It is now generally recognized that steels and non-ferrous alloys possess at temperatures not greatly exceeding that of the atmosphere, characteristics quite different from those existing at ordinary temperatures, and that they assume qualities similar to those of the soft metals. Not only have they no limit of elasticity, but the proof stress and the ultimate stress depend on the time of application of the load. Flow under load may persist for long periods of time, possibly indefinitely, and the determination of a true maximum stress becomes a matter of great difficulty.

Jan 1, 1939

By P. H. Mell

AMONG the minerals exhibited at the Atlanta Exhibition of 1881, soapstone, kaolin, and asbestos were well represented. The first two occur in large quantities, of very pure quality, throughout the South. The last is somewhat limited in amount, get in certain localities it exists in masses sufficiently large to pay for working; in North Carolina, Georgia, and Alabama it has ken mined with some profit. I would, in this paper, call special attention to the minerals soapstone and kaolin, because their many valuable qualities seem to have been almost entirely overlooked by our Southern manufacturers. Steatite, particularly, occurs in such large quantities, and generally in such close proximity to the great iron regions of Alabama and Georgia, that it is anlazing that the iron companies will persist in sending abroad under heavy expense for firebrick. It would require a much smaller sum of money to quarry this rock and place it at the various furnaces ; and the results obtained, I am sure, would prove its superiority over the majority of firebrick brought into this region. Soapstone, as well as kaolin, is found throughout the metamorphic regions of Alabama, Georgia, South Carolina, and North Carolina. Below will be found seven analyses that I have made of this mineral, taken from various points in the four States above mentioned. I have also subjected these same specimens to severe fire-tests, and the results were very satisfactory. The tests mere canducted in the following manner: Small portions of the compact variety were carefully weighed and placed in a Fletcher&apos;s new crucible furnace for gas, and subjected for half an hour to a heat that will in 12 minutes fuse iron. The only effect upon these specimens was a slight change in color to a darker shade, a small loss in weight, due evidently to the evaporation of water, and, in one or two specimens, a slight degree of fusion on the sharp edges. The first specimen subjected to investigation was taken from a large outcropping in Tallapoosa County, Alabama. Specific gravity, 2.88 ; hardness, 1.9; color, blue gray. Composition: Water,....2.68 Silica,..........65.48 Iron oxide,.........2.10 Alumina,.........15.02 Magnesia,... 15.35 10061

Jan 1, 1882

By Frank C. Kelton

A method is outlined for the analysis of large cores, developed primarily for the purpose of obtaining reliable data on fractured or vugular limestones. Porosity and fluid saturations are determined by a modified Dean-Stark extraction after initially bringing the samples to 100 per cent liquid saturation by a vacuum-pressure method. Horizontal permeabilities on the whole samples are determined in two directions, parallel and perpendicular to the di-rection of principal fracturing. Results are presented for various types of formations. A comparison is made between data obtained by this special method and the method of conventional analysis, and discussion is given of the relative advantages and limitations of each. In view of this comparison a modified method for the analysis of fractured and vugular formations is proposed, which method retains the advantages of the previously outlined techniques but gives promise of speeding up the analysis. INTRODUCTION For many years the greater part of the production in the Permian Basin was from formations of Permian and Pennsylvanian age. While production from these formations is still the predominant production. deeper prospecting has brought to light older formations with oil productive characteristics. Attempts to core these deeper horizons were at first usually characterized by poor recovery. The old rule of thumb, "good core recovery — poor well" was originated and remained in effect until recently. With the advent of diamond coring and the increased efficiency in drilling and coring operations. the old adage has lost its significance. Formations of Devonian. Silurian and Ordo-vician ages were successfully cored with varying degrees of recovery. The cores thus obtained were surprising and in some case; disappointing. Good recovery from these formations led to speculation as to the feasibility of analysis and the meaning of data obtained from conventional analysis. Commercial laboratories were engaged to analyze these cores. and their results indicated that data obtained by conventional methods would be of little value. From visual inspection it was apparent that in many cases the effective porosity for storage of hydrocarbons. and permeability. were contained largely in fractures and solution cavities rather than in the primary crystalline structure of the formation. In other cases the solution cavities augmented the effective porosity of the primary crystalline structure, or fractures enhanced the permeabiilty of the latter so that the formation might respond favorably to acidization and become commercially productive. Since the spacing of the cavities and fractures was often comparable to the core diameter, it was evident that the entire core should he analyzed instead of small fragments. On the basis of these observations, commercial laboratories were requested to devise a system of analysis which would yield data of practical value. Pro- cedures have accordingly been developed which seem to meet this requirement, and to date nearly 12,000 large core samples have been analyzed. It is the purpose of this paper to describe the methods used, to present typical results for several fractured formations and to compare the data obtained by this special analysis with that obtained by conventional analysis. Certain modifications and alternative procedures are finally suggested to speed up the analysis. CORE ANALYSIS PROCEDURE Fluid Saturations and Porosity The core sample, in segments up to 15 in. in length. is marked, weighed and examined under ultra-violet light to determine the presence of oil saturation. If present, the approximate quantity of oil and its location on intercrystalline, fracture or vugular surfaces is noted. This information is carefully recorded. The degree of fracturing and/or vugular development is also noted. The sample is then placed in a pressure cell and the air evacuated with a high speed vacuum pump. This evacuation is continued only long enough to reduce the pressure to approximately the vapor pressure of water in order not to remove excessive amounts of water. Water is admitted to the cell and allowed to penetrate the sample under atmospheric pressure, filling the pore space initially occupied by air and replacing the small amount of water removed by evacuation. Pressure up to 200 psi is applied to force water into the smaller capillaries, and the sample is left sub-

Jan 1, 1950

By M. J. Bradley, P. H. Dike

THE art of melting nonferrous metals, in smelting, casting, and in compounding of alloys, is highly dependent on a knowledge of the temperature of the metal. This knowledge may reside in the experience and judgment of the melter, or it may be based on measurement by suitable instruments. It-is our purpose to discuss briefly the instruments available for such measurements, and more at length the present, practice in molten metals, without recommendation. In the limits of time and space allotted, we can do little more than mention the available methods of measurement that are directly applicable in this field. In the 1939 edition of the Metals Handbook, issued by the American Society for Metals, pages 285-310, there is a more extensive discussion of pyrometry than can be attempted here, which should be referred to for details we must omit. For reasons that will appear, thermoelectric pyrometry will constitute the major portion of our discussion of the subject, only limited attention being given to radiation or optical pyrometry. METHODS OF MEASUREMENT THERMOELECTRIC PYROMETRY A thermocouple consists of two dissimilar wires, or a wire inside a tube of a dissimilar material, joined together at one end, which is placed in the region or medium where the temperature is to be measured, while the other ends are connected through suitable lead wires to a voltage-measuring device, which may be a millivoltmeter or a potentiometer. An electromotive force is generated in the circuit, which is proportional to the difference in temperature between the hot junction and the junctions of the lead wires to the measuring instrument. If this latter temperature is maintained constant, the e.m.f. measured varies only with the temperature of the hot junction. Every thermoelectric pyrometer is calibrated for a particular cold-junction temperature such as 0°F., 32°F. or 75°F., but usually it is more practical to compensate instrumentally over the probable range of cold-junction temperatures than to maintain the junction at the particular temperature for which the instrument was calibrated. Thermocouple Materials Only a very few pairs of metals are in frequent use for pyrometric measurements. The most generally used are iron-constantan for temperatures up to 1500°F. in oxidizing and up to 1800°F. in reducing atmospheres and chromel-alumel, which may be used in oxidizing atmospheres at temperatures up to 2400°F. for intermittent service. The accuracy of the latter deteriorates rapidly at temperatures above 2200°F. Platinum vs. platinum-rhodium thermocouples may be used up to a temperature of 3000°F , but they are easily contaminated by slow absorption of

Jan 1, 1946