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By C. R. Johnson, R. A. Greenkorn, R. E. Haring

Three confined five-spot miscible displacements at unity, favorable, and unfavorable mobility ratios were conducted in a shallow, water-saturated sandstone of Pennsylvan-ian age near Chandler, Okla. These studies, plus associated laboratory experiments, were designed to measure miscible displacement performance in a controlled natural system, using known scaling criteria to develop an approach to modeling the heterogeneous field system. We have concluded from these studies that: (I) displacement efficiency in the field is a pronounced function of mobility ratio, indicating that miscible fingering observed in simple laboratory models occurs in the field: (2) field displacements can be quantitatively predicted by scaled laboratory models if the degree and location of field permeability variations are preserved in the models: and (3) arbitrary simplifications of heterogeneity will not necessarily predict observed displacement efficiency, and the simpler the model, the more optimistic the prediction. INTRODUCTION Many processes to achieve miscible displacement of reservoir oil by injected fluids have been conceived and field tested by the oil industry. Among the better known are high-pressure gas, enriched gas, and LPG banks. The simplest form of miscible displacement—one fluid miscibly displacing another fluid of different viscosity but the same density—has been studied extensively in homogeneous laboratory models. Observations of unstable fingering have been made which explain the significant decrease in displacement efficiency as the mobility ratio (ratio of displacing fluid mobility to displaced fluid mobility) increases. General industry experience with field tests of miscible displacement projects, mostly LPG banks, has been premature solvent breakthrough and lower than predicted production rate increases. These results have been attributed to either unstable fingering, unusual or unexpected permeability stratification, or both. Miscible displacement data in a controlled natural system have never been reported, however. Also, it has not been shown that properly designed and constructed laboratory models quantitatively predict field-scale behavior. The purpose of the combined field and laboratory ex- periments reported in this paper is twofold. The first was to measure miscible displacement performance at different mobility ratios in natural rock approaching field size under precise, controlled conditions. The second purpose was to utilize known scaling criteria plus several approaches to heterogeneity to model the field. Comparison of model and actual field results should then determine whether or not the laboratory phenomena (manifested by miscible displacement efficiency) are exhibited in large, natural rock systems. We carried out our program by first locating a shallow, water-saturated reservoir whose rock properties were representative of oil-bearing reservoirs. Detailed reservoir description by core analysis and interference testing showed the field site to be heterogeneous. A sequence of controlled, aqueous-phase miscible displacements was conducted at unity, favorable and unfavorable mobility ratios. A central, confined pattern was used to obtain the displacement data. A laboratory program using sand-packed models was conducted to determine the modeling criteria necessary to simulate field behavior of miscible displacement in a heterogeneous system. SCALING THEORY The detailed derivations and descriptions of the scaling laws that apply to laboratory models of reservoirs are adequately described elsewhere, so the following discussion will be restricted to facets of importance in this study. For a displacement in which one liquid miscibly displaces another, the following dimensionless groups are required to have the same numerical value in the model as in the field: The model also must be geometrically similar to the field, be spatially oriented the same as the field (same dip angle), and have the same initial and boundary conditions as the field (same initial fluid saturations and same injection-production well arrangement). When these conditions are satisfied, the theory predicts that at dny dimensionless time (pore volumes of produced fluids) the dimen-sionless flow potential and dimensionless fluid concentrations will be identical at all dimensionless spatial locations within the model and the field. If this prediction is correct, then the local dimensionless velocities must be identical, thus the instantaneous fraction of displaced fluid produced and the cumulative recovery expressed as fraction of original fluids in place must be identical at all dimensionless times. The theory outlined above has been obtained by either dimensional analysis or inspectional analysis of differential

Jan 1, 1966

By J. W. Graham

For many years the author has been cognizant of the difficulty encountered by some in treating with the water influx formulas for unsteady-state fluid flow as pertain to the material balance equation. This has particularly applied in establishing reservoir performance and identifying reservoir pressure, which to the practicing engineer has entailed a trial-and-error procedure, and for others has necessitated resorting to computing devices and reiteration processes. In retrospect this difficulty stems from the fact that reservoir pressure in the material balance formulas, as well as associated with the water influx equations, is an inexplicit term, and the work reported in the past is irrefutable. However, what will be presented in this paper is another approach to the problem, whereby the entire material balance equation will be treated by the Laplace transformation, and reservoir pressure which hereto has been inexplicit, can now be isolated by mathematical procedure to relate that parameter with all the factors contributing to its change. This is the simplification entailed, that treats first with an undersaturated oil reservoir as an integrated effect from the inception of production. The second phase pertains to saturated oil reservoirs that encompass a survey traverse. Although both methods of approach are necessarily different in aspect, the most interesting fact is that the mathematics so deduced are identical. Both the linear and radial water-drive systems are incorporated. for which an illustrated factual example is offered for the latter, treating with a saturated oil reservoir. INTRODUCTIO N What is performed in this work is the simplification of an involved computation by advanced analysis. Although such may be construed as a contradiction when one treats with higher mathematics; nevertheless, when direction is given to such an undertaking the results car. be most revealing. Likewise, it is to be mentioned that the bases for these mathematics have been developed on the expediency of the occasion. This is not to be inferred as a qualification of this work, but rather the demands frequently placed upon the author in his private prac- tice in meeting a time limit. A situation, instead of being fraught with hazards, often has given emphasis to creative thought. What will be entailed in this work is the simplification of the material balance formulas by the Laplace Transformation., Although this reveals entirely new horizons that will be given expression in a forthcoming tract, it suffices in the present instance to limit our attention to this phase of the development that treats both with an undersaturated and saturated oil reservoir. To orient the reader's thoughts as to what is involved in this simplification is the recognition that reservoir pressure, as such, is an inexplicit term in the material balance equation. This is the independent parameter that defines the total history of performance in the author's' unsteady-state water influx formulas, as well as the basis for the physical dependency of fluid behavior within the formation as prescribed in the Schil-thuis' material balance equation. Therefore, to isolate reservoir pressure, which is the most essential factor in any reservoir study, is rather a cumbersome procedure entailing either a trial-and-error calculation for the engineer; or as some prefer, a reiteration process performed on a computing device. However, once such an equation can be transcribed as a Laplace transformation, this inexplicitness so expressed can be alleviated to identify reservoir pressure as an explicit function of all the factors contributing to its change. This is the simplification encompassed, that will treat first with an undersaturated oil reservoir as an integrated effect from the inception of production, and secondly, with a saturated oil reservoir as a survey traverse. Although the two approaches are necessarily different because of the uhvsics involved. it is an interesting commentary that the mathematics are identical, showing the interdependency of the two methods. In order to acquaint the reader with this development, the simplest case will be treated first; namely, an under-saturated oil reservoir subject to a linear water drive. However, what may be construed for this example as an idealistic case is actually a most practical application in certain parts of the world, where the size of the fields are so large that radial water-drive approaches the configuration of a linear drive. Further, to avoid the repetition of much symbolism, frequent references will be made to the work of the author and an associate on Laplace Transformations3,

By N. H. van Lingen

A laboratory stud], has been made to determine what factors affect the penetration rate of roller bits, diamond bits and drag bits in rock drilling with clay /water muds. The rather simple relations that exist when pressures in and around the borehole are equal become more conzplicated when under down-hole conditions the penetration rate is hampered by the existence of a pressure differential between the mud at the hole bottom and the pore liquid at cutting depth. Expressions that have been derived for both the penetration rate and the magnitude of the pressure differential in permeable rock together fully account for operating, rock, mud and bit variables. In impermeable rock a similar pressure differential is caused by the bit action itself. In all cases, the pressure difierential and the reduction in penetration rate increase with the effectiveness of the plastering at the bottom of the hole by mud particles. Where bits are employed whose action is largely that of crushing, however, the plastering may become even more effective owing to the addition of rock particles rubbed into the pores of the rock. With roller bits, a plastically hehaving layer may be formed, which causes a further reduction in penetration. In the case of bits whose action is chiefly scraping, moreover, penetration may be arrested by the bit's becoming balled-up. The various adverse effects are reduced by thorough scavenging of the hole bottom. This paper shows how with jet bits the efficiency of such scavenging may he improved by suitable choice of the position of the nozzles. INTRODUCTION The reduction in a bit's penetration rate with increasing depth of hole has been the subject of many investigations. Various investigators ',' have independently reached the conclusion that this reduction occurs not so much because the rock-breaking process becomes more difficult as it does because the lifting of the rock fragments is impaired by a fluid pressure differential holding the fragments down. When such a pressure differential can be avoided, as in air drilling and to a smaller extent in water drilling, penetration rates remain high. Although the range of applicability of these techniques is being extended, most oil wells still have to be drilled with mud. In this paper we present the results of laboratory experiments carried out to determine what factors govern the hold down effect encountered in mud drilling. In the course of this investigation, the well known importance of bottom scavenging came more and more into prominence. Not only may it reduce the magnitude of the hold-down forces, but also it appeared to be a means of preventing the accumulation of a plastic mass of cuttings and mud on the hole bottom and bit which may cause penetration to cease almost completely. So that the effects of fluid pressures may be more readily understood, the factors that govern penetration rate in the absence of these pressures will first be discussed. The effect of down-hole pressures will then be assessed for the case of permeable rock where fluid pressures are well defined, and it will be demonstrated how rock strengthening due to confining can be accounted for. Subsequently, fluid pressures in less-permeable rock will be examined; we will show that in impermeable rock it is the bit action that governs fluid-pressure distribution and hold-down. In the case of poor scavenging and/or high bit load. cutting cake manifests itself. The effect, like various others. appears to depend on the type of bit used. From the very beginning, therefore, we shall base our discussion on the three main types of bits used in rotary oil-well drilling— roller bits, diamond bits and drag bits. Since space is limited, it will be impossible to make more than a passing reference to many aspects of the problem. Moreover. certain relations that are not of primary irnportance to our argument will unavoidably have to be stated in a somewhat dogmatic fashion, and the experimental data on which these are based necessarily must be omitted. EQUIPMENT The drilling experiments were performed on three machines, of which one has been designed for the realistic simulation of down-hole pressure conditions. HIGH-PRESSURES MACHINE In this machine (diagramed in Fig. 1) the mud, pore and confining pressures can all be adjusted independently. The foil-covered rock sample contained in the inner pressure vessel is confined by oil that is pressurized by means of a hand pump. The pore space of the watersaturated sample is connected to an arrangement which keeps the pressure in the pore space constant regardless of the rate of filtrate flow through the sample.

By E. A. H. Tays, F. A. Schiertz

In 1893 the Anglo-Mexican Mining Company, Limited, purchased the Guadalupe and adjoining mines, and, after opening up the Guadalupe, constructed a 20-stamp mill, which was started in August, 1894. Although the results were extremely profitable (the ore being very rich and carrying much free gold) they were not satisfactory, because the tailings were found to average about $20 per ton in gold. Early in 1895 the late Mr. James E. Mills made for the company a very thorough study of the subject, and decided that the tailings could be treated most advantageously by the cyanide process. In view of this opinion, Mr. Henry R. Batcheller, of Boston, was sent down in the winter of 1895-96 to experiment on a working scale. Mr. Batcheller was successful; and, during 1896-97, built a cyanide-plant with a capacity for treating 1500 tons per month. This was run until May, 1899, when all the sands suitable for the process had been treated. The mill was stopped about the same time for lack of ore; but no tailings from the mill had gone to the dump since October, 1897, as the values they contained after that date were far too low to warrant further treatment. When the cyanide-plant was stopped there still remained on the dump about 16,000 tons of slimes, consisting of about 75 per cent. of clay-slimes and 25 of sand-slimes. The successful treatment of this very unfavorable material is the theme of this paper. Fig. 1 is a view of the hacienda, taken in 1897.

Jan 1, 1902

By D. L. Archer, W. W. Owens

Conventional waterflooding often is uneconomic in highly fractured reservoirs because of the gross bypassing of the reservoir oil by injected water. Imbibition and pressure pulse flooding have been used in at least one fractured reservoir in an attempt to achieve better oil recovery performance. This paper presents the results of laboratory flow tests conducted on large cores to evaluate the possible applicability of these methods (particularly pressure pulse flooding) to different types of reservoir systems. Test data were obtained on both water-wet and oil-wet systems, and on systems having two widely different levels of compressibility and flow capacity. Results indicate that pressure pulse recoveries from fractured reservoirs will likely not exceed 5 to 10 per cent pore space with maximum response achieved during the first pulse cycle. Improved recovery by this method is possible from both oil-wet and water-wet reservoirs. Comparable saturation distributions during imbibition and pressure pulse production suggest that an initial pressure pulse cycle to speed production response would not interfere with subsequent imbibition flooding in water-wet reservoirs. INTRODUCTION There is a steady increase in the number of fluid injection projects being initiated each year to improve oil and gas recovery over that obtained by primary production mechanisms. Experience gained in different geographical areas and with different recovery methods is teaching that reservoir anatomy is one of the more important factors controlling the success or failure of such projects. Fractured formations appear to be the rule rather than the exception, especially in carbonate reservoirs. Conventional methods of fluid injection, whether it is waterflooding, gas injection or miscible flooding, have limited applicability to highly fractured reservoirs because of the severe bypassing of reservoir fluids. The result is early breakthrough of the injected fluid and rapidly increasing ratios of injected to in-place fluid with an undesirable effect on return on investment. Thus, innovations to conventional methods must be developed if recovery from fractured reservoirs is to be optimized. One new method proposed for application to highly fractured reservoirs is pressure pulse waterflooding. Although pressure pulsing with gas has been suggested' and rested in at least one reservoir; the Sohio Oil Co. is generally credited with the development and testing of pressure pulsing in conjunction with waterflooding. Publications" of Sohio's waterflood operations in the Spra-berry Trend indicate that the idea for pressure pulse flooding evolved from a critical analysis of the disappointing early performance of their flood initiated in a portion of the trend in April, 1961. This flood was planned to take advtantage of imbibiltion and high pressure gradients across the reservoir matrix blocks (unfractured Mocks of the reservoir rock which are visualized to be generally surrounded 'by the fracture system) evaluated in pilot tests by the Atlantic Richfield Co.5 and Humble Oil & Refining Co.' However, the early recovery and pressure performance of this flood indicalted that high pressure gradients induced between the fracture system and the centers of the matrix blocks were forcing water into the periphery of the blocks and temporarily interfering with the counter-current flow of oil due to imbibition. Fill-up in the blocks was occurring with re-solution of the free gas phase as pressures climbed above the original reservoir bubble point. It appeared that cessation of water injection to permit the capillary forces to become dominant and that expansion of the rock and its contained fluids during pressure reduction might aid in expulsion of oil from the rock matrix into the fractures. Subsequent production performance. aflter cessation of injection, proved this hypotheslis correct. Thus, pressure pulse waterflooding was born. Pressure pulse flooding appears to have several advan'tages over imbibition type flooding in highly fractured reservoirs. First, all wells may be used for water injection which should hasten fill-up and achieve a more rapid increase in reservoir pressure. Second, because of increased injection pressures and rates, flooding gradients will force water into the reservoir matrix more rapidly than would be achieved by imbibition alone. Third, during the pressure depletion cycle of the flood, the compressibility of the system, which has been increased by resolution of the free gas phase, provides energy for the displacement of oil at a rate greater than would correspond to countercurrent flow during imbibition. Fourth, during depletion all wells may be put on production, thus contributing to higher oil withdrawal rates on a reservoir-wide basis. One possible disadvantage of pressure pulse flooding as compared to imbibition floodling, however, is that the outer periphery of each matrix block is flooded to a residual or near residual oil saturation during the Water lnjection stage. This zone of reduced permeability to oil m'ay offer greater restriction to the production of

Jan 1, 1967

By J. R. Vilelia

IN accordance with the custom of this society, we are gathered here, as we have every year since 1924, to honor the memory of the eminent American metallurgist and teacher, Professor Henry Marion Howe. Unlike many of the distinguished metallurgists who have preceded me as a Howe lecturer, I cannot bring to you reminiscences of his personality, for it was not my privilege to be associated with Professor Howe, or to be directly one of his students. Yet, Professor Howe and Professor Albert Sauveur, through the medium of their books, were my first teachers of metallography, as they have been of almost all American metallurgists of my generation. As a teacher, and for many years the acknowledged leader of American metallurgists, he exercised a profound influence in the growth of our science and was held in honor by the men of science of his time. I can speak no words of technical appreciation that will add luster to his fame, for by his prophetic vision, his teachings, and his researches he stands among the immortals in the memory of all metallurgists. In 1926, the third Howe Memorial Lecture was presented by Professor William Campbell' of Columbia University, who entitled it "Twenty-Five Years of Metallography." He took as a starting date for his chronology the turn of the century, which coincided with his arrival from England to work in association with Howe at the Columbia School of Mines. In that informative lecture Professor Campbell enumerated the important advances in metallography achieved during the first quarter of the century, and, it now appears, may have established the custom of reviewing such progress every twenty-five years. The scope of Professor Campbell's lecture was as broad as his metallurgical knowledge, for it embraced a wide portion of the field of metallography, both ferrous and nonferrous. Twenty-five years later, the Howe Memorial Lecture Committee saw fit to assign to me the honor of writing a lecture that would commemorate the work of Henry Marion Howe and would at the same time constitute the 25th anniversary of the lecture by Professor Campbell. The Committee suggested that this lecture might properly be called "Twenty-Five More Years of Metallography," a suggestion that I have adopted. I must confess, however, that I have not followed the precedent established by Campbell and have narrowed the scope of this lecture to an appraisal of those achievements which in my opinion have contributed most to the progress of microscopical metallography during the past twenty-five years. Progress in Metallography The metallographic methods most widely used today, with the exception of the electron microscope, were firmly established more than twenty-five years ago. In general, our specimens were prepared for microscopic examination in those days in much the same manner as they are today. It is true that new details of technique have been introduced from time to time, and that superior equipment is available today, but on the whole, these improvements have been in the nature of refinements, often a matter of personal preference, and none can be considered essential to the attainment of the ultimate goal of the art and science of metallography, which is to reveal the structure of metallic specimens with unequivocal clarity so that they may be interpreted correctly. Mechanical metallographic polishing, which was the only method available in 1926, is still universally practiced and still consists of abrading the metallic specimen with a series of abrasives of increasing fineness until a specular surface is attained. We have now the alternative method of electropolishing, but it is not widely used because, except in a few special cases, its results are inferior to those of competent mechanical polishing. Likewise, most of the etching reagents preferred today were in common use more than twenty-five years ago and were applied in the same manner as they are today. Valuable improvements have been made in the optical and mechanical performance of metallurgical microscopes, but there was no dearth in those days of excellent instruments equipped with achromatic and apochromatic objectives capable of yielding micrographs comparable in quality with the best that we can make today. In fact, it would be a difficult task for any metallographer today to make optical micrographs at magnifications in excess of 3000 diameters that would surpass those made by Lucas more than twenty-five years ago. One of these is shown in Fig. 1. Yet, it is unquestionable that on the whole, the micrographs appearing in the metallurgical literature today are vastly superior to those

Jan 1, 1952

By Charles L. Mantell, James E. Hoffmann

Mechanical inclusion, electrophoretic deposition, and adsorption were studied as mechanisms for code-position of aluminas present in copper-plating electrolytes as an insoluble disperse phase. Mechanical inclusion was not a significant factor. That codeposi-tzon of aluminas by an electrophoretic mechanism was unlikely was substantiated by measurements of the potential of the aluminas. The alumina content of the deposits was studied as a function of the pH of the bath. These tests in conjunction with sedimentation studies demonstrated the absence of an isoelectric point for the alutninas over the pH range examined. Thiourea in the electrolyte (a substance known to be adsorbed on a copper cathode during electrodeposition) affected the amount of alumina in the electrodeposit. However, no adsorption of thiourea on aluminas in aqueous dispersions was detected. If it were possible to produce a dispersion-hardened alloy of copper and alumina by electrodeposition, an alloy possessing both strength and high conductivity at elevated temperatures might be anticipated. Investigation of the mechanism of codeposition of aluminas with copper was undertaken with the hope that knowledge of the mechanism would aid in the development of such an alloy. The word "codeposit" here does not necessarily imply an electrolytic phenomenon but rather that the materials codepositing, the various aluminas, are transported to and embedded in the electrodeposited copper by some means. Mechanical inclusion in electrodeposition implies a mechanism of codeposition which is wholly mechanical in nature; the only forces acting on a particle are gravity and contact forces. Such a particle is presumed to be electrically inert and incapable of any electrical interaction with electrodes in an electrolytic plating bath. Processes for matrices containing a codeposited phase by electrodeposition from a bath containing a disperse insoluble phase frequently state that code-position is caused by mechanical inclusion.10,2,12 If settling, i.e., gravity, be the controlling mechanism for codeposition of aluminas, then assumptions may be made that 1) the content of alumina in the electrodeposit should be enhanced by increasing the particle size, 2) the geometry of the system, that is, the disposition of the cathode surfaces relative to the di- rection of the falling particles, should affect the alumina content of the electrodeposit, 3) in geometrically identical systems the chemical composition of the electrolyte employed should exercise no effect on the alumina content of the deposit, that is, the alumina content should be the same in all cathode deposits irrespective of bath composition. A bent cathode19 evaluates the clarity of filter effluent in electroplating baths by comparing the roughness of the deposit on the vertical surface with that on the horizontal surface. Two difficulties are inherent in this technique: 1) the current density on the horizontal portion of the cathode would be substantially greater than that on the vertical surface; 2) should the deposit obtained be rough, projections on the vertical face could act as horizontal planes and vitiate the relationship between the vertical and horizontal surfaces. Bath composition should have no substantial effect on the alumina content of the deposit. Two different electrolytic baths were employed. They possessed variant specific conductances and substantially different pH ranges. The experimental tanks were rectangular Pyrex battery jars 6 in. wide by 3 1/4 in. long by 9 3/4 in. deep. The cathodes were stainless steel 316 sheet of 0.030 in. thickness, cut to 7.5 by 1.75 in. and bent at right angles to form an L-shaped cathode whose horizontal surfaces measured 1.75 by 3.0 in. All edges and vertical surfaces were masked with Scotch Elec-troplaters Tape No. 470. The anodes were electrolytic cathode copper 9 in. high by 2.25 in. wide by 0.5 in. thick. To eliminate inordinately high current densities on the projecting edge of the cathode, the anode was masked 1 in. above and below the projected line of intersection of the cathode with the anode. The exposed area of the anode was equal to that of the cathode, providing both with equal average current densities. The agitator in the cell was of Pyrex glass and positioned so its center line was equidistant from cathode and anode, and a plane passed horizontally through the center of the blade would be located equidistant from the bottom of the cathode and the bottom of the deposition tank. The assembled apparatus is depicted in Fig. 1. Hatched areas on anode and cathode represent the area of the electrodes wrapped with electroplaters tape. MATERIALS The chemicals were copper sulfate—CuSO4 • 5H2O— technical powder (Fisher Scientific Co.). Spectro-graphic analysis showed substantial freedom from antimony, arsenic, and iron. Traces of nickel were present.

Jan 1, 1967

By D. T. Goettge, E. L. Robinson

The phase changes occurring in low carbon steel during hot strip mill rolling are shown to be metallurgically significant when related to commonly used temperature control points, particularly finishing and coiling temperatures. In combination, these temperatures are shown to have an important influence on the level and uniformity of hardness, grain size, and carbide characteristics of the finished hot and cold rolled sheets. PRODUCTION of wide flat-rolled products ordinarily requires a number of operations in sequence to prepare the material for shipment to the customer. Most products are tailor-made for specific end uses, with each operation contributing certain properties to the finished material. Since the characteristics imparted to the semifinished product by a given step in processing carry through to the finished product in varying degrees, it is important that the intermediate stages of production of flat-rolled strip be carried out with the same care which characterizes the last or finishing operations. The step of hot strip mill rolling is common to the production of all of the various types of flat-rolled product; therefore, the hot strip rolling is an especially important point at which to recognize and control those variables which have an effect on the surface characteristics and metallurgical properties of the finished product and which influence the ease of conducting subsequent operations. Orders entered at a producing mill usually show an end use or describe an article or part into which the ordered product is to be fabricated. Applying his experience as to the properties necessary in a finished sheet to suit the end use and to perform successfully in the fabrication involved, the metallurgist selects a steel of suitable composition and deoxidation practice, and slabs of appropriate dimensions are produced for rolling on the hot strip mill. At this stage of processing, the metallurgist faces the problem of controlling hot strip mill practice in the light of his diagnosis of the properties necessary to meet the end use, paying due attention to the accompanying problem of producing a strip which can meet processing requirements on subsequent units in the mill. It is the purpose of this paper to describe some of the factors which he must consider in solving these problems and to indicate some of the principles which guide him. Equipment, Physical Requirements of the Strip, and Temperature Measurement The metallurgist must, of course, be familiar with the physical layout of the mill, the temperature-measuring equipment available, and the physical requirements of the hot strip product before he can apply his metallurgical knowledge to the problem; hence, the first section will consist of a brief discussion of these matters. The usual hot strip mill consists of reheating furnaces, five or six roughing stands including a scale-breaker, holding table, and second scalebreaker, six-stand finishing mill, runout table with spray cooling facilities, and coilers. A schematic diagram of a typical layout is shown in Fig. 1. Slab temperatures are primarily a function of heating time and furnace temperatures, while mill speeds, spray practice, drafting practice, available water pressure, temperature of the cooling water, cross sectional dimensions of the strip, coil size, and equipment limitations, either singly or in combination, determine what rolling temperatures are practical on a given hot strip mill unit. Thus, it is possible that a set of temperatures which can be utilized successfully on one mill cannot be used on another. However, adjustments in temperatures and rolling practice can usually be made to develop the desired metallurgical properties. In addition to the metallurgical properties developed through proper temperature control, the hot strip mill must also provide strip with certain physical attributes which may be summarized as follows: Strip Cross Section—The strip contour should conform to a section which will give the best results in the cold reduction operation. This is generally recognized as a strip with 0.001 to 0.003 in. crown or shoulder-to-shoulder convexity depending on width, and freedom from concave, flat, or wedge-shaped cross sections which cause metal buildup in cold reduction. Excessive drop off in thickness at the edges can also be very detrimental in cold reducing to light gages. Gage, Width, and Camber—All of these must be controlled. For example, rundown or increasing thickness from the front to the back of the coil results in nonuniformity in the thickness of hot-rolled sheet product and in added difficulty with gage and welds in cold reduction. Similarly, excessive width variation is the cause of guide trouble and excessive edge scrap at later stages of processing, while excessive camber is the source of a variety of processing troubles. Type of Oxide—Product intended for pickling should have a predominance of the type of oxide most easily removable in sulfuric acid. It is generally recognized that this type is obtained by use of maximum table cooling water and cold coiling

Jan 1, 1957

By C. D. Hall, F. E. Dollarhide

Fluid Ioss agent.s for crude oil and for water have been studied in dynamic tests. A treatment using a spearhead with a fluid loss agent followed by plain fluid appears feas ible in crude oil, but not in water. An equation for spearhead depletion shows that spurt loss relative to fracture width must be low, if the portion of spearhead fluid in the treatment is to be small. The presence of colloidal matter in crude oils aids the fluid Ioss agent. Unlike in kerosene, where flow limited the agent deposition, in crude oils the filter cake continually formed and leak-off declined. The volume-time relation varied somewhat for different crudes, but was best described by a square root of time function. Spurt loss was inversely proportional to agent concentration. After the fluid loss agent initiated the filter cake, the crude oil colloids built on it effectively. A 2-minute or a 5-minute spearhead with double the normal agent concentration gave the same fluid Ioss curve as the same concentration did for a 30-minute test. The agents tested in water gave fluid Ioss plots on which, for the first few minutes, volume was proportional to the square root of time, but later became proportional to time. For fracture area calculation the customary square root of time function is a satisfactory approximation. Leak-off rates and spurt losses were higher in water systems than in oils. The spurt Ioss tended to be inversely proportional to concentration. In spearhead tests, the filter cakes were not eroded by water flow. However, the rather high spurt loss values make spearhead treatments impractical for water-based fluids. Introduction The effects of dynamic testing conditions on the performance of fluid loss agents in kerosene have been studied previously.' We have extended the work to include crude-oil- and water-based fracturing fluids. An understanding has been gained of the mechanisms of formation and functioning of the filter cakes of fluid loss agents. The practical aspects of evaluating performance of agents in relation to fracture area calculations also are considered. The feasibility of using the fluid loss agent in a spearhead stage of the treatment is examined further for both types of fluids. Experimental Procedure The dynamic fluid loss tests were performed in an apparatus similar to the high-pressure apparatus described in a previous publication.' A fracturing fluid was circulated over a rock surface located in a closed pressurized loop. The fluid flowed axially over the cylindrical surface of a core 2 in. in diameter X 3.5 in. long, mounted (with the flat ends sealed off) in a pipe, with 0.117 in. annular clearance. The filtrate was collected in a central hole in the core and led through valves to graduated cylinders. Provision was made for changing quickly the circulating fluid during the test (spearhead runs) without interrupting the filtration pressure. The only modifications were to add heating tapes and water jackets for the tests with crude oils, all conducted at ISOF, and to change all parts exposed to the test fluid to stainless steel for the tests with water-based fluids. The latter tests were made at room temperature, 80F. Three crude oils were tested. A mixed crude, obtained from a local refinery, contained a considerable amount of light ends. For safety reasons, it was stripped to 250F vapor temperature before use in the fluid loss tests. The other two oils were used as obtained from lease tanks. One was a greenish-brown, 37" API paraffinic crude, and the other was a black, 32" API asphaltic crude. The fluid loss agent for oil, here designated for brevity as Agent A, was Adomite@ Mark II*, a granular solid commercial agent, the same as previously tested in kerosene.' Three different compositions of fluid loss agents were tested in Tulsa tap water. Agent B was adomit& Aqua*, a solid commercial fluid loss agent, comprising clays and hydrophilic gums principally derived from starch. Agent C was a mixture of three parts of Agent B with two parts of silica flour. Agent D was Dowel1 J137, a mixture of guar gum and silica flour. The test cores were cut from contiguous blocks of Berea or Bandera sandstones. For the oil tests, the cores were oven dried, evacuated, saturated with kerosene, and the kerosene permeability was measured. The cores used with the water-based fluids were pretreated by saturating with 3 percent calcium &loride solution to minimize pemeability damage by the fresh water due to clay migration. The

Jan 1, 1969

By B. H. Kear, B. J. Piearcey

The orientation and temperature dependence of the tensile and creep propevties oj Mav-M200 crystals halle been determined. Crystals oriented for single slip exhibit ,maximum ductility, minimum work hardening, and least creep resistance, whereas crystals in multiple slip orientations show nzinimu~n ductility, strongest work hardening, and greatest creep resistance. At 1400" and 1600°F there is a marked improzlenzent in creep strength for orientations approaching [001] and [111], indicating that interactions between dislocations gliding in intersecting octahedral slip systems play an important role in creep resistance. At 1800°F the creep strength is much less dependent on orientation, which is rationalized in terms of slip in cube planes as well as octahedral A frequent mode of failure in high-strength cast nickel-base superalloys is by intergranular fracture, particularly along those grain boundaries oriented transverse to the major stress axis. VerSnyder and ~uard' demonstrated that this problem could be overcome by eliminating transverse grain boundaries through unidirectional solidification. Piearcey and versnyder2 made use of this principle in the development of unidirectionally solidified gas turbine blades and vanes, where the growth direction of the columnar grain structure coincides with the axis of principal stress under operating conditions. The present investigation was undertaken to determine if further improvement in properties may be obtained by eliminating grain boundaries altogether, so as to take advantage of the well-known dependence of mechanical properties of single crystals upon the orientation. 1) EXPERIMENTAL PROCEDURE Single crystals of Mar-M200* were grown from the melt under vacuum by a modified Bridgman method. The melt was poured into a preheated alumina mold, and crystal growth was promoted from one end by appropriate gradient cooling. Tensile and creep specimens (2 in. diam by $ in. gage length) were prepared by a series of operations involving electrical discharge machining, precision grinding, and electropolishing. The orientations of the specimens were determined by the Laue X-ray back-reflection method. Tensile tests were carried out in aWiedemann machine with furnace attachment, using a strain rate planes. In all orientations imzpvouement in the strength charactevistics of the material can be induced by heat treatment. Creep ad stress rupture data for (001) oriented crystals are compared with similar data obtailted previously joy random polycvystalline material, and also columnar grained material having a prejevved (001) orientation. The single-crystal )material exhibits both longer rupture life and lower minimum creep rate at all temperatuves, and the rupture elongation is comparable with that in the columnar grained material. From these results it is concluded that single crystals should and useful application in gas-turbine blades and tanes. The optimum orientation for a blade is considered to be with its axis of principal stvess parallel to (001) ou (111). of 0.0001 sec-'. Load and extension were recorded directly on an X-Y recorder. The strain measuring device consisted of extension arms attached to the grips at one end and leading out of the furnace to an LVDT (linear variable differential transformer) at the other. Creep tests were performed using a standard constant load creep frame. 2) DISCUSSION OF RESULTS 2.1) Structure of Alloy. The structure and segregation in as-cast and heat-treated Mar-M200 has been described in detail else where.~ The main features are as follows: the as-cast material is heavily cored, due to pronounced dendritic segregation during solidification; the dendrites are rich in tungsten and cobalt whereas the interdendritic regions are rich in chromium, titanium, nickel, and carbon. The structure consists of -60 vol pct coherent precipitate of y', basically Ni3(A1,Ti), in a matrix of y (nickel-base solid solution), interspersed in the interdendritic regions with minor MC carbides and -y' eutectic. The y' particles, and y-y' eutectic, contain more titanium, aluminum, and nickel, and less tungsten, cobalt, and chromium than the y matrix. Heat treatment partially removes segregation, eliminates the eutectic, refines the y' dispersion in y, and gives additional partially coherent M23Cs carbide. An as-cast crystal, therefore, is composed primarily of two oriented phases (y + y'), whereas the normally heat-treated crystal consists of three oriented phases (y + y' + MZ3Cs). Typical electron transmission micrographs of the y + y' structure are shown in Fig. 1. Crystals grown in the (100) orientation develop a simple unidirectional dendritic structure, Fig. 2, since (100) happens to be the preferred direction of growth for dendrites in this material. Crystals grown in the {110) and (111) orientations, however, tend to promote equal growth, generally in separate colonies, in the two and three geometrically favored (100) growth directions, respectively. In other orientations of growth, a single (100) dendrite direction generally pre-

Jan 1, 1968

By AIME AIME

THE meeting of the Petroleum Division at Houston, Oct. 10-12-headquarters, Rice Hotel-was preeminently a technological success. Two hundred and twenty-five attended the Thursday morning session and approximately 200 attended the sessions on Thursday and Friday afternoons and Saturday morning. Harry Power, Chairman of the Division, in his opening remarks, credited Paul Weaver and M. Albertson, respectively chairman and vice-chairman of the local committee, with working long and prodigiously in organizing the program. The theme of the initial session was indicated by Mr. Albertson in a statement relative to the estimation of developed petroleum reserves. He said that the problem of securing more accurate estimates of developed petroleum reserves existed prior to curtailment of production. With curtailment, however, the problem became an acute one. Mr. Albertson gave some of the more important reasons for this situation. Since the decline-curve method became inapplicable, the volumetric method has become the chief one used. It depends on the factors of productive formation volume, porosity, saturation, and recovery. He briefly discussed the factors necessary for application of the volumetric method. P. P. Gregory discussed the estimation of petroleum reserves in prorated lime¬stone fields (see his paper in the October

Jan 1, 1935

By F. W. Jessen, N. Mungan

The plastic flow characteristics of clay water suspensions were first recognized by Binghaml in 1916 and further studied by Ambrose and Loomis' in 1931-1932. Many physical and chemical properties of clay suspensions are deeply influenced by particle size distribution as well as by the exchange cation. Separation of a number of fractions is particularly helpful in making a detailed study of a suspension. A limited amount of work has been conducted on the effects of particle size on specific properties of mud drilling fluids. A knowledge of particle size distribution is essential for a better understanding of fundamental properties of clay suspensions, particularly viscosity and gel strength. The purpose of this investigation was to study the effect of particle size on the viscosity and gel properties of clay suspensions and to determine any changes in mineral composition accompanying variation in size. EXPERIMENTAL PROCEDURE Numerous methods may be used to fractionate a poly-dispersed clay suspension into nearly mono-dispersed systems. Particles larger than 44 micron (325-mesh) may be obtained by wet screening. For sizes from 44 to 1 micron, the fractionation may be accomplished by sedimentation, elutriation plus microscopy,' or turbidimetry.6 When dealing with systems which contain a major portion of particles below l-mi-cron size, slit ultramicroscopy,7 centrifuge methods of Svedberg,5 eams,9 and McBain,l0 and X-ray methods" may be employed. The Sharples super centrifuge has been proved suitable for the economical separation of suspended particles of submicron range.12,13,14 Three-hundred and forty-five gal of 1 per cent by weight Aquagel suspension was mixed in a high-speed 5-gallon mud mixer and the suspension was allowed to stand in 5-gal glass bottles for 30 days to assure full hydration. All particles larger than 44 microns were removed by wet screening. Five fractions in the range of 44 to 1 micron were obtained by sedimentation. The Sharples super centrifuge method described by Hauser and Reed.13 Norton and Speil,14 Ha user and Lynn,15 and Hauser and Schachman,10 as employed to yield five fractions of submicron size. A super centrifuge operation chart prepared by Fancher, Oliphant, and Houssierre12 was used to determine operating conditions for the desired particle ranges. The clay suspension, after removal of all material above 1-micron size, was centrifuged. During rotation of the bowl, the particles were deposited on a thin plastic liner which fit closely inside the bowl. After passing 5 gal of suspension through the centrifuge, the liner was removed and the particles on the liner were scraped off, remixed and recentrifuged. This was repeated five times. Thus, Fractions H, I, K, and L were obtained. The finest fraction, M, remained in an approximately 0.4 per cent suspension. Water was evaporated under reduced pressure from this suspension to yield the finest particles. Results of the fractionation are included in Table 1. In order to achieve proper orientation and humidity conditions for X-ray diffraction analysis, the following procedure was employed. The dilute suspensions were placed on glass slides and allowed to dry at room temperature. This was repeated several times. Previous to measurement each sample first was placed in a water desiccator for half an hour and then allowed to stand for 15 minutes at room temperature. thus yielding an equilibrium condition of about 52 per cent relative humidity. The relative humidity of the room in which the X-ray diffraction was carried out was maintained at approximately 50 per cent so that there was no change in the spacings during the X-ray examination. Samples

By Benj. Lazer

Multiple seam mining has been studied and writ- ten about extensively in the past and in the latest review of the subject in 1956 David Stemple covered it exhaustively. The present discussion has to do with only one phase of the problem-"The effects on upper seams when the lower seams have been mined first." The study presented here is based on observations made in mining operations in southern West Virginia and adjoining areas of Virginia and Kentucky during the past 43 years. These observations are largely confined to the Pocahontas coalfields of southern West Virginia which have, since 1883, produced well over one billion tons of coal from an area of about 300 sq miles and where multiple seam mining has been active, or is now active, at more than 40 operations. The observations and conclusions as to the effects on upper seams when lower seams have previously been mined are therefore related only to the local coalfields in the area of the three states named but I believe that they can be applied generally to other coalfields.

Jan 9, 1965

By K. A. Natarajan, I. Iwasaki

Platinum electrodes are not inert as often thought to be. The reactivity of platinum electrodes can explain their erratic behavior in many electrochemical measurements of metallurgical interest, e.g, in flotation systems, streaming potential measurements, contact-angle measurements, and in leaching systems. The anomalous behavior of platinum electrodes in redox potential measurements in aqueous systems was studied through Eh and pH measure ments in water-oxygen, iron-water-oxygen, and manganese-water-oxygen systems. Stability relations between Fe++ and Fe (OH), and between Fe (OH), and Fe (OH), were studied to judge the correspondence between experimental and theoretical equilibrium lines. The practicality of redox potential measurements in estimating ferric-ferrous ratios in aqueous systems was investigated along with their suitability as indicators in leaching operations, e.g., the removal of iron by aeration from manganese leach solutions. Platinum electrodes have often been used in the measurement of dissolved oxygen concentrations and of redox potentials (Eh) in a variety of fields, e.g., analytical chemistry,' corrosion," geology and mineralogy,,'' biology,"' sewage treatment,' * hydrometallurgy,"I" and flotation."la The effectiveness of Eh-pH diagrams, first reported by Pourbaix' in 1949, has contributed much towards the theoretical understanding of numerous problems encountered in the metallurgical industry. Not many references are available in the literature, however, wherein attempts have been made to confirm Eh-pH diagrams from experimental measurements. One reason might be that, in spite of the apparent simplicity of the electrochemical technique, the direct measurement of Eh involves complex practical problems.' Factors such as the purity of the solution, the type of electrodes used, the history of the indicator electrode, and the type of atmosphere (namely, oxidizing, reducing, or inert) do have effects on the measured Eh values. The influence of mixed potentials cannot be underestimated. The poisoning of platinum electrodes by organic and inorganic impurities present in the solution may lead to erratic results. Platinum, commonly thought to be an inert electrode material, is not really so, as attested by a number of previous investigators who advised caution concerning the anomalous behavior of platinum electrodes in various electrochemical measurements.'" In the present article, a few pertinent experiments related to Eh-pH measurements in systems of interest in the metallurgical and water pollution fields are described in an attempt to correlate such information with what is already known, especially in the electrochemical literature. Iron-water and manganese-water systems were selected with a view of studying the correspondence between experimentally observed and theoretically established equilibrium lines. The work included an investigation of the behavior of platinum electrodes with respect to pretreatment and adsorption characteristics, the measurement of dissolved oxygen concentrations and their relation to Eh, the determination of the electrode potential of the ferric-ferrous couple at different pH, and the measurement of oxidation potentials in iron-manganese leaching systems. Experimental Procedure A rotating platinum electrode was used in many of the measurements to study the effect of rotation on measured Eh values. The electrode made by the Pine Instrument Co. consisted of a stainless steel rod with a platinum disk soldered to the end. It was covered with a Teflon insulation along the sides, so that only the circular tip of the electrode was exposed to the solution. Prior to its use, the platinum surface was brightened on a metallurgical polishing wheel with alumina as an abrasive, unless specified otherwise. The electrode was rotated with a Sargent cone-drive motor at 350 rpm. The contact of the electrode with the external circuit was made by filling a notch at the top of the stainless steel shaft with mercury and by dipping a copper wire into the mercury pool. The performance of the rotating platinum electrode was compared with the performances of a Beckman platinum button electrode and a platinum wire electrode. All the potentials were measured with respect to a saturated calomel electrode. A saturated KC1-agar bridge was used to minimize the liquid junction potential. A Beckman Zeromatic pH meter together with a Beck-man electrode switch was used to measure both the Eh and pH. A double-walled, all-Pyrex jar with a capacity of about 1 liter and themostated by circulating water of constant temperature was used for a reaction cell. Four equally spaced ports in the cover provided access for a glass electrode, a salt bridge connecting the saturated calomel electrode, a dispersion tube for bubbling gases into the cell solution, inlet and outlet tubes for passing the desired gases over the solution, and a graduated burette for introducing reagents from outside. The rotating platinum electrode was inserted through an opening in the top-center of the cover, and a positive gas pressure was maintained inside the cell to prevent air from entering into the cell compartment. A magnetic stirrer was used to mix the solution inside. For the determination of dissolved oxygen in the test solutions, the polarographic techniquex was used.

Jan 1, 1971

By H. W. Winkler, Discussion, V. L. Forsyth

The development of a new gar lift valve has removed many of the obstacles limiting over-all gas lift efficiency. The valve is pressure charged in place in a well, and operating pressure can be changed without pulling. Temperature and gas gradient compensation have been eliminated. Intermitting and constant flow installations, using conventional pressure-charged valves, are compared with designs incorporating the new automatic stabilizer controlled valve. Specific well performance data are presented. The means of obtaining and controlling multiple-point injection of gas are explained and contrasted with single point injection. The effect on small diameter strings and multiple string installations is discussed. The effect of flowing temperature gradient on a design using conventional pressure-charged valves, the limitations imposed by such temperature, and the obvious benefits which result from the use of automatic stabilizer controlled valves are shown. Reduction of gas requirements is stated mathematically and demonstrated with specific examples which are identified as to oil company and well. Increased fluid recovery resulting from greater drawdown is illustrated. The economic advantages are mentioned with emphasis on reduction of capital expenditures, as well as reduction in operating expenses. INTRODUCTION Much of the engineering and research work performed with gas lift has been based upon the supposition that under producing conditions gas would be injected at a single point in a well. Many tests were performed in determining the optimum size of the opening through which gas would be passed and the exact placement of the valve equipment. The objectives in a gas lift installation are to unload the well and to efficiently produce the well after it is unloaded. Until recently, the function of upper valves was simply to unload the well. An operating valve located at a proper place in a well served as a single injection point for lifting liquid to the surface. The basic problem in using such equipment is to arrive at operating depth with sufficient operating pressure to efficiently lift the liquid. Few gas lift installations are designed with all required well data available. However, regardless of the quality and availability of data, and regardless of the accuracy of the design, there is the practical problem of preparing and placing gas lift equipment in the well in exact accordance with the plans and intentions of the engineer. In recognition of these and many other problems, attention was directed toward a means of removing the need for temperature and gas gradient compensation, a way to change the gas lift installation to meet the changing requirements of the well itself, and a manner of compensating for changes in oil-water content, fluid volumes, PI, and bottom-hole pressure resulting from flood or repres-suring activity. A device which could actually set and change the operating pressure of gas lift valves in the well would meet most of these needs. There now exists a new gas lift valve which fulfills the original objectives and in so doing actually accomplishes much more. With this device, called an Automatic Stabilizer Controlled valve, there is an exact matching of valve operating pressure and well conditions. Gas is injected at more than one point in the well, thereby making controlled multiple-point injection of gas a reality. Installation calculations are materially simplified and the need for basic temperature and gas gradient data no longer exists. Section I—The Automatic Stabilizer Controlled Valve The operation of the ASC valve is more easily understood by first studying a conventional pressure-charged valve and then inserting the stabilizer element to observe the changes which result. Fig. 1 is a schematic of a conventional precharged pressure-operated valve. The pressure in the dome pd, acts downward, against the area of the bellows A,, to hold the valve closed. The resulting force Bf plus the spring effect of the bellows Sf represents the total force acting to close the valve. Correspondingly, the tubing pressure ptbg works upward against the port area Atbg and the casing pressure pc works upward against a portion of the area of the bellows

Jan 1, 1965

By E. A. von Hahn, T. R. lngraham

The rates of cementation of pd11 on electropolislzed copper cylinders were studied in aqueous perchloric acid solutions at pdII concentrations from 0.02 to 0.1 mM. The cylinders were rotated at various high speeds to reduce the diffusion layer to a minimum thickness. In 0.1 M HClO4 solutions, the cemented palladium is dense, adherent, and shiny. The rate data indicate that there are two stages in the deposition. In the initial stage, the rate of cementation is first order with respect to the pd11 concentration. The second stage is much slower. The first stage is consistent with rate control by the diffusion of pd11 ions to the copper surface, and/or chemical reaction at the surface, and the second stage is consistent with rate control by the diffusion of copper ions from the cop-per surface through the deposit of cemented palladium, out to the main body of solution. In 0.001 M HClO4 solution, only the first stage is evident and the rate is more rapid than at higher acidities. This rate enhancement is attributed to PdOH+ ions that predominate at low acidity and aye more reactive than unhydrolyzed pdII. The deposit is porous and loose. All of the cemented deposits are Pd-Cu alloys rather than pure palladium. Activation energies are 9.5 kcal per mole in 0.1 M HClO4 and 7.4 kcal per mole in 0.001 M HClO4. CEMENTATION or displacement reactions occur between aqueous solutions of metal salts and immersed metals according to the general equation: where M1 is electrochemically the more noble metal. Although these reactions find considerable application in metals recovery processes (e.g., the cementation of copper192 or gold3), in electrorefining processes (e.g., solution purification before electrolysis4,5), and in plating and metal finishing processes,6 few studies have been made of the kinetics of such reactions.7-9 The rates of cementation reactions will depend on one or more of the following factors: a) chemical reactions at the metal-solution interface; b) ionic transport to or away from the interface;'-' and c) the character and adherence of the cemented deposit on the substrate metal,6a,10 because the deposit will inhibit the rate of transport of dissolving ions (M2m+) into the solution. In this investigation, the kinetics of the early stages of cementation were studied to obtain an understanding of the reaction mechanism under conditions in which the deposit was sufficiently thin that its inhibiting effect could be disregarded. To achieve this, very dilute solutions in Mn+ were used. Cementation rates are often fast in the initial stages and transport-contr01led.9 To find conditions under which transport control would shift to chemical control, very high stirring velocities were used to minimize the diffusion-layer thickness. Of the many possible cementation reaction systems, the palladous perchlorate-copper system was chosen for this investigation because it was believed to involve simple ion-for-ion exchange. In addition, there are no interfering side reactions, such as the reduction of hydrogen ions, and anion effects are usually absent in perchlorate solutions. EXPERIMENTAL Materials. Reagent-grade chemicals and redistilled water were used in all experiments. Palladous perchlorate stock solutions (0.02 M) were prepared by dissolving 99.5 pct Pd sponge (Johnson Matthey and Mallory Ltd.) in concentrated nitric acid, adding concentrated perchloric acid, evaporating twice slowly (to prevent PdO precipitation) to a small volume, and diluting in a volumetric flask. To prevent gradual hydrolysis of PdII, the stock solutions were made 0.4 M in HC104. Tests for pdIV (Ref. 11) and C1- were negative. Copper strips were cut accurately from 0.025-in. electrolytic tough pitch sheet, Sample 1 (Mines Branch stock or Canadian Copper Refineries Ltd., Montreal), or from oxygen-free, high-conductivity sheet, Sample 2 (American Metal Climax O.F.H.C. brand, sold by Utility Brass and Copper Corp., Brooklyn). The strips were annealed for 1 hr at 335°C in a stream of purified nitrogen (Union Carbide, Linde Division) which had

Jan 1, 1967

By R. G. Ward, D. R. Gaskell

Using the maximum bubble pressure technique, the densities of iron silicates at 1410°C have been measured blowing helium, nitrogen, and argon. By ensuring equilibrium between the melt and the blowing gas with respect to oxygen potential and by minimizing tempcrature cycling of the furnace, iron precipitation in the melt has been prevented. Thus the previously reported effect of blowing-gas composition on the densities of the melts has been eliminated. Consideration of the oxygen densities of the melts gives an indication of the structural changes accompanying composition change. The density-composition relationship of iron oxide-silica melts in contact with solid iron has been the subject of several investigations1-7 and considerable disparities exist among the various results obtained. Of these investigations, all except one5 have employed the maximum bubble pressure method. In the most recently reported of these investigations1 the density-composition relationship obtained blowing nitrogen differed from that obtained blowing argon. The measured densities obtained under nitrogen were greater than those obtained under argon, the difference being a maximum at the pure liquid iron oxide composition and decreasing with increasing silica content. This observation rationalized the disparities existing among the results of the earlier investigations, showing that two lines, one for nitrogen and the other for argon, could be drawn to fit all the earlier results. No explanation for this phenomenon could be offered. Chemical analysis of rapidly quenched samples of melt for dissolved nitrogen, and direct weighing measurements, excluded solution of nitrogen in the melt from being the cause of the increase in density. The range of blowing gases was extended by Ward and Hendersons who measured the density of liquid iron oxide bubbling helium, nitrogen, neon, argon, and krypton. The measured density was found to decrease smoothly with increasing atomic number of the bubbling gas. The work reported here is a continuation of the program initiated by Ward and Sachdev7 to study the densities in multicomponent melts in which the iron oxide-silica system is the solvent. As such it is necessary to explain or eliminate the anomalous densities of iron silicates under different atmospheres, and the present rede termination was carried out towards this end. EXPERIMENTAL The maximum bubble pressure method of density determination was again employed and the experimen- tal apparatus used was essentially the same as that used by Ward and Sachdev.7 A molybdenum-wound resistance furnace heated an ingot iron crucible of internal diameter 1 in. containing a 2-in. depth of melt. The bubbling gas was blown through a 1/4 -in.-diam mild steel tube onto the end of which was welded a 2-in. extension of 1/4 -in.-diam ingot iron rod, drilled out to 5/32 in., and chamfered to an angle of 45 deg. The blowing tube was introduced to the furnace through a sliding seal and its position was controlled by a vertically mounted micrometer screw which allowed the depth of immersion to be determined with an accuracy of ± 0.01 cm. A Pt/Pt-10 pct Rh thermocouple was located below the crucible and temperature control was effected initially by means of an on-off controller and later by a saturable core reactor. The bubble pressure was determined by measurement of a dibutyl phthalate manometer using a cathetometer. PREPARATION OF MATERIALS Iron oxide was produced by melting ferric oxide in an inductively heated iron crucible in air. The liquid was quenched by pouring onto an iron plate. Silica was prepared by dehydrating silicic acid at 650°C for 12 hr. RESULTS Before any measurements of the density of a melt were made, the density of distilled water at room temperature was measured bubbling helium and argon. Both gases gave the density as 1.00 ± 0.01 g per cu cm which showed that the density of the manometric fluid (dibutyl phthalate) was not affected by contact with the blowing gas. With the furnace controlled by an on-off temperature controller an attempt was made to measure the density of pure liquid iron oxide by bubbling argon. The furnace atmosphere gas and bubbling gas were dried over magnesium perchlorate and deoxidized over copper turnings at 600°C. It was found that the pressure required to blow a bubble at a given depth increased slowly with time, and thus it was impossible to obtain a unique value for the density of the melt. Inspection of the blowing tube after removal from the furnace showed that rings of dendritic iron had precipitated from the melt onto the immersed part of the tube. This is shown in Fig. l(a) where the various "steps" correspond to different depths of immersion. The precipitation of iron was considered to be due to one or both of two possible causes: i) The composition of the liquid iron oxide is that of the liquidus at the temperature under consideration and can be expressed by the equilibrium

Jan 1, 1968

By G. T. Davis, C. C. Mattax, M. O. Denekas

The effects of crude oil cornponents on the wellabil-ities of sandstone and limestone were investigated. Fractions containing cornponents differing in molecular weight and molecular structure were obtained from crude oils by distillation, extration and chromatography. Individual fractions were then tested for their effects on rock wettability. Tests indicate that sundstone wetta-bility may he changed by a complex variety of surfactants varying both in molecular structure and molecular weight. Limestone appears to be particularly sensitive to basic, nitrogenous surfactants. INTRODUCTION Investigations in recent years have shown that petroleum reservoir rock wettability can exert a significant influence on the efficiency with which oil can be produced by water flooding. While most reservoirs are presumably water-wet, they niay range in their degree of water-wettability from near-neutral to strongly water-wet.'" Reservoir wettabilities other than strongly water-wet are likely to be induced by adsorption of surface-active components froni the crude oil on the pore walls of reservoir rock.:' Little is known, however, about the nature of the surface-active materials which are likely to be adsorbed by the reservoir rock. Due to the complexity of crude oils. attempts made in the past90 isolate these surface-active components have met with only limited success. It is probable that many different types of surface-active materials arc indigenous to crude oils and that many of these may be adsorbed to varying degrees by reservoir rock. This was cxolored in the studies discussed in this paper. The over-all objective in these studies is to ascertain whether the wettability of a given reservoir can be determined by examining the surfactant content of the reservoir crude. To this end, crude oils were examined to determine the variability of indigeneous surfactants with regard to chemical type and molecular weight. Crude oils were separated by distillation into fractions differing principally in molecular weight, by chroma-tography into fractions containing compounds differing in polarity, and by solvent extraction into nitrogenous and non-nitrogenous fractions. Individual fractions were then tested for their effects on the wettabilities of sandstone or limestone rock samples. EXPERIMENTAL PROCEDURES Fractionation of the Crude Oils Samples of Miocene, Eocene and Jurassic crudes were distilled at temperatures not exceeding 200°C. The final stages of distillation were completed in a molecular still at pressures down to three microns of mercury. Fifteen to 30 fractions were obtained from each crude oil. These cuts were sufficiently broad that separation can be considered to have been effected principally on the basis of the molecular weights of the constituents of the crude oil. A considerable portion (20 to 40 per cent) of the crudes would not distill under these conditions. The residues were recovered and tested with the other fractions. Fractions differing in polarity were separated from a crude of Pennsylvanian age and an extracted sample of Miocene oil by chromatography, using a solid adsorbent. Since surfactants are, for the most part, polar compounds, chromatography should separate many of the surfactants from the crude oil. Such a separation should provide fractions containing compounds differing in molecular structure. Nitrogeneous compounds were extracted from Miocene crude oil with a solution of sulfuric acid in meth-anol. The residual oil was further processed by chonia-tography. Each of the fractions obtained by thesc procedures was dissolved in a non-polar solvent (xylene) and diluted to its original concentration in the crude oil. No attempt was made to maintain an anaerobic atmosphere above the samples while they were being dissolved. These solutions of the fractions were then tested for their effects on the wettability of sandstone and limcstone as discussed in the next section. Measurement of the Effects of Crude Oil Fractions on Rock Wettability No entirely satisfactory method for measuring rock wettability has yet been developed. All methods used are empirical. The imbibition test was used in these studies. This test is based on the tendency of a rock to imbibe the wetting phase spontaneously. For example, if a strongly water-wet rock is first saturated with oil and then placed in water, the water will quickly invade the rock by capillarity and much of the oil will be displaced. If the rock is slightly water-wet, water irnbibition will proceed more slowly and, in many instances, considerably less oil will be displaced. A water-saturated, oil-wet rock will imbibe oil. The initial rate with which water (or oil) imbibition takes place indicates, qualitatively, the degree of water (or oil) wettability of the rock.

WHEN pouring concrete it frequently happens that space prohibits the placing of a mixer at the point, or points, where the concrete is to be used. Usually in such cases recourse is had to some form of pressure chamber, or concrete gun, to blow the mix by compressed air from the mixer to the point of pouring. Recently such a case arose at one of the western mines. The experience obtained there may be of benefit to others, not expert in the means of transporting mixed concrete, when they run up against similar situations. The first stage in pouring in this instance was a vertical drop of 100 ft. from the mixer on one level to the point where horizontal travel began on a lower level. Standard 6-in. pipe with flange joints was used, hung in the shaft space available. A standard 45" bend near the bottom directed the mix, with free discharge, into an air chamber for the horizontal stage of travel. With an air chamber at the mixer and pressure applied to the falling mix in the vertical section, jamming frequently occurred at the turn and the pipe would have to be taken apart for freeing. To obviate this difficulty the mix was poured slowly without the addition of air pressure, when it was found that the mix got through much better.

Jan 1, 1929

By John J. Porter

UNUSUAL problems have arisen at certain iron blast-furnaces in Virginia through the fact that the ore-supplies, derived from the Oriskany formation, contain from a trace up to 1 per cent. of zinc oxide. Since the technical literature bearing on this subject is very scant, the following notes, based on personal experience, will probably be of value to those of our members who are interested in iron blast-furnace practice. The course of zinc through the blast furnace is readily traced. Entering the throat as zinc oxide, finely disseminated through the ore, it descends unchanged to the fusion-zone, since a temperature of 1,000° C. or more is required for its reduction. At the fusion-zone, the zinc oxide is reduced by solid carbon to metallic zinc, which is set free as vapor and rises with the ascending gases to the cooler zones of the furnace. In cooling through the range of temperature from 1,000° to 500° C. the zinc is re-oxidized according to the reaction Zn + CO2 = ZnO + CO, and the resulting zinc oxide, being in a very fine state of division, is readily carried along by the ascending gases. Portions, however, deposit on the descending stock and are carried down, again to pass through the same cycle of changes. Still other portions deposit on the lining of the stack, and gradually form hard masses of "cadmia." Of the remainder of the zinc oxide, the greater part passes out of the furnace, and is either deposited in the down-comer, dust-trap, stoves, boilers and flues, or passes through the chimney into the atmosphere. A small portion escapes reduction and enters the slag as zinc oxide, while still another portion is absorbed into the lining of the furnace.

Sep 1, 1907