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By V. R. Garfias, H. J. Hawley

FoR a number of years the senior author has been interested in the various geologic and engineering problems involved in the development of the petroliferous districts of northeastern Mexico, having in a previous paper* endeavored to present a summarized statement of the information relating to the geology and soil resources of this region. Of the many interesting geologic phenomena, perhaps those which have been the object of most speculation relate to the igneous intrusions which, in places, have a controlling influence on the accumulation of oil in commercial quantibies, a relationship which has been tentatively explained by various observers with as many interestingly different views. The authors of the present paper aim to record, in the course of a general discussion of the various viewpoints, some additional data, and present further tentative conclusions with a view to rounding out an up-to-date summary of the subject. The greater part of the area in question lies in the State of Vera Cruz, only a northwest fraction being in the State of San Luis Potosi. Vera Cruz is bounded on the north by the State of Tamaulipas, the northernmost of the Mexican States along the Gulf. The topography of the States of Tamaulipas and Vera Cruz and of Texas and Louisiana to the north, is controlled by the Gulf coastal plain which in northern Vera Cruz has an average width of about, 60 miles, the transitional topography between that of the rugged Banks of the Sierra and the lowlands of the coast being made up of a series of terraces and irregular hills and valleys. Geology and StRucture The greater part of the mainland of Mexico is made up of Tertiary and later effusive rocks and of sedimentaries of Cretaceous age. The igneous rocks form a belt from 150 to 300 miles wide, spurs of which shirt

Jan 1, 1918

By H. L. James

This paper presents the results and analysis of field trials of various magnetic instruments over anomalies ranging from 20 to 5000 gammas of vertical intensity. The following instruments were used: Askania vertical magnetometer, Wolfson vertical magnetometer (model M-I), Hotchkiss Superdips (used both parallel to and normal to the magnetic meridian, with several settings of the "sigma" angle), Lake Superior dip needle, and the dipping circle for measurements of inclination. The change in inclination over the measured anomalies ranged up to 4"; this caused pronounced changes in sensitivity of the Hotchkiss Superdip oriented parallel to the magnetic meridian. The variable sensitivity not only gives apparent displacement of crests of anomalies, particularly at high sensitivities, but also makes the data difficult or impossible to use in preparation of iso-anomaly maps. This weakness in field performance of the Superdip is shown to be eliminated by orienting the instrument normal to the magnetic meridian and measuring vertical intensity only, which in the latitude of upper Michigan is equal to 97 pct of the total intensity. The dip needle is seen to be relatively ineffectual for location of anomalies of less than 400 gammas. Introduction The U.S- Geological Survey, in cooperation with the Geological Survey Division of Michigan Department of Conservation, has for the past three years been engaged in a restudy of the Iron River-Crystal Falls iron mining district of upper Michigan. The bedrock in a large part of this area is covered with glacial deposits as much as 500-ft thick, and, inasmuch as some of the rocks have moderate to high magnetic permeability, extensive magnetic mapping has been done to assist in unraveling the complicated structure of the area. Several types of instruments have been used, and the major purpose of this paper is to present comparative data on the field performances of some of these instruments so as to aid others who face similar problems elsewhere to evaluate and choose the instruments best suited for the work. The paper is directed primarily to geologists and engineers rather than to geophysicists, although some familiarity with the instruments is presumed. The geology of the area consists of a complexly folded series of weakly metamorphosed sedimentary rocks, including the iron formation, which rests on older greenstones. Although the iron formation itself is only locally magnetic, some of the beds stratigraphically above the iron formation are rather strongly so. By tracing these hanging wall magnetic anomalies valuable information is obtained from which the structure and distribution of the iron formation can be inferred. Critical anomalies range from 25 to 6000 gammas of vertical intensity. Many anomalies can be traced in part with the common dip needle, but detection of others requires more sensitive instruments.

Jan 1, 1949

By A. Phillips, H. J. Fisher

The influence of temperature and composition on the viscosity of high-purity liquid metals and alloys of the Pb-Sn and Sb-Cd systems was investigated by the logarithmic-decrement method. The variation of viscosity with temperature above the liquidus followed the equation: n = AeE/RT No large increase in viscosity was found just before normal freezing of any of the metals or alloys investigated. Certain alloys, supercooled below their stable liquidus, however, did show a marked increase in viscosity. Experimental activation energies for viscosity were determined for the metals investigated. Liquid-metal density values were obtained by a modified Joeger's method. IK an investigation of the properties of molten metals, the study of viscosity as a suitable means for studying the physical nature of the metallic liquid state has been utilized. Although interest in the relationship of the liquid to the solid-metal state holds promise of broadening the knowledge of metals in general, much information that is available regarding the influence of temperature and composition on viscosity, especially near the freezing point, is still controversial. The purpose of this paper is to present the results of recent work on this subject. Although interest in factors influencing the fluid behavior of metals and alloys has arisen from theoretical as well as applied studies of liquid-metal properties, the development of a comprehensive theory of the mechanism of viscosity has been handicapped because so little is known about the liquid state. Several theories of viscosity have been proposed and among the more recent are those of Andrade,1 Bernal,2 Frenkel,3 Eyring,4 and Gutmann and Simmons.5 Athough these contributions have helped to establish a basis of approach for studying the nature of viscosity, the fundamental aspects of the variation of viscosity with alloy composition have, in general, been neglected. Experimental Metals and Alloys Investigated: The Pb-Sn and Sb-Cd alloy systems were selected for investigation because they form constitutional features of theo-

Jan 1, 1955

By William H. Spice

The area on which oil and gas development is reported covers 30 counties, which are included in the Texas Railroad Commission's District No. I. This area not only includes the old established Balcones fault-line group of producing fields but also includes the southwest extension of this trend and some of the deeper Wilcox (Eocene) exploratory development. (Fig. J.) In the old Balcones fault-line zone, three new fields were discovered during 1941. These fields are comparatively small, producing from Dale limestone or Austin chalk. No new fields were discovered during the year in the Edwards (Lower Cretaceous) limestone horizon. One new shallow field was discovered in the Reklaw (Eocene) sand horizon and, in the southwestern part of the district, one oil field and one gas field were discovered in the Navarro (Upper Cretaceous) sand horizon. An extremely important extension was made to the one producing Wilcox (Eocene) field of the district in the Washburn Ranch field of La Salle County. The district produced 6,650,357 bbl. during 1941, which was a 12 per cent decrease under production for 1940. Approximately 4,954,000 bbl. of this total production was produced by the three Edwards limestone fields, Luling, Salt Flat and Darst Creek, the remaining production coming from the other 43 active fields in the district. In all, 3694 wells were producing at the end of 1941, compared with 3559 wells at the end of the previous year. During the year, 139 new producing wells were completed and 29 wells were abandoned in the producing fields. The increase in producing wells represents an increase in new wells over abandonments in these fields, together with a decrease in wells temporarily shut down as of the end of 1941. The majority of production drilling was carried on in the following fields; Bee Creek, Chicon Lake, Elm Creek, Gas Ridge, Pearsall and Tenney Creek. Approximately 250 wells were drilled during 1941, of which 110 were exploratory wells completed as failures throughout the district. Considerable exploratory work was continued during 1941 along the Wilcox trend. Geophysical work employing various types of geophysical methods and leasing activity was continued along this trend, particularly by the major companies. The significance of this activity is apparent from the successful extension and development in the Washburn field of La Salle County, where several well-developed gas-and-oil producing horizons have been developed in the lower Wilcox section between 5100 and 5600 ft. as noted in the following paragraphs. Continued exploratory activity along this general trend as far as present conditions will permit is predicted for 1942. New Fields Elgin Field, Bastrop County.—No. I-A Hiram Walker, Marts and Beaven, Inc., discovery well of the Elgin field, was com pleted on Apr. 22, 1941, in broken Austin chalk from 2820 to 2840 ft., pumping 105 bbl. per day, 36.8°A.P.I. gravity. The well apparently is producing from a crevice in

Jan 1, 1942

By Oliver Bowles

AMONG mining men as well as in the popular mind the conviction has held sway that mining is pre-eminently a western industry. True it is that gold, silver, copper and other metals have made the States of California, Colorado, Montana, Utah. Nevada and Arizona famous. The prominence attained by these States as mineral producers is, however, not measured alone by the money value of the products of their mines. While the metals are without doubt indispensable in industry, the glamour of the precious metals, and the lure of copper, lead and zinc have given to their ore deposits a sentimental interest that often quite out-weighs their commercial importance. Today a great group of more commonplace minerals are finding a place in commerce and industry rivaling that of the metals, but there is little sentiment attached to them, and,. therefore, they attain relatively little publicity. This is the great group of the non-metallic minerals, exclusive of fuels and oils, including stone, sand and gravel, cement, lime, gypsum, asbestos, mica, phos-phate rock and many others. Almost unnoticed they have grown in production to almost unbelievable pro-portions. The estimated value of metal production for 1925 is given as $1,380,000,000, of the non-metals (ex-cluding fuels) $1,294,000,000. The non-metallic industries are not new, many of them date back almost to pre-historic times; but, as the greatest of them (on a tonnage basis) provides raw materials for the construction industries, it required the activities of the present age of construction to bring about their enormous development. Many of them enter manufacturing as well as con-struction. Non-metallic minerals constitute the back-bone of our great chemical industries. While construction and manufacture reach to all parts of the country their widest development has been in the great industrial centers of the eastern Seaboard and the middle West. Consequently the raw materials of mineral origin required for these great industries have attained a remarkable growth in the eastern half of the- United States. In compiling figures of mineral production for 1924, for which more complete data are available than for later years, the surprising fact is brought to light that the non-metallic mineral produc-tion alone of some of the eastern and middle-western States exceeds by a substantial margin the total min-eral production of some of the western States that have been classed as essentially mining States. Thus the non-metallic mineral production, exclusive of coal and petroleum, of the State of Ohio, was approximately $150,000,000; of Pennsylvania $175,000,000; and of New York $107,000,000. For the same year, 1924, the total mineral production of Utah was $84,357,000; of Montana $70,632,000; of Colorado $61,488,000; and of Nevada only $26,226,000. Even Minnesota, with its enormous iron ore production, reached only $107,845,-000, or a sum about equivalent to the non-metallic min-eral production of the State of New York.

Jan 8, 1927

By W. M. Peirce, R. K. Waring

Zinc of high purity offers definite advantages in certain fields. A process by which zinc of 99.99 + per cent purity is produced by pyro-metallurgical methods is described in this paper. The process consists of a fractional distillation following the primary reduction; this fractional distillation employs the principles of rectification for the separation of lead and other high-boiling impurities and cadmium and other low-boiling impurities. Theoretical Considerations Involved in Production of High-purity Zinc by Distillation Fractional distillation, fractional condensation, and rectification are recognized methods of separating mixtures of liquids. In the field of organic liquids these methods are widely used but not commonly to effect as complete a separation of liquids as is done in the problem under consideration. Zinc boils at 905" C., cadmium at 778" C. and lead at about 1620" C. Zinc may contain from several hundredths of one per cent to over one per cent each of cadmium and lead, and the problem is to reduce these impurities to a few thousandths of one per cent. For lead and zinc, the spread in boiling points is substantial, 715° C., while for zinc and cadmium it is only 127" C. The basic limitation of any separation by distillation may be found from the relation between the equilibrium composition of the vapor and the liquid for all mixtures of the two substances involved. If a mixture of constant boiling point is found, or if a stable compound that vaporizes without dissociation occurs, there is a definite theoretical limit to the degree of separation that is possible when operating at atmospheric pressure with respect to that mixture. Otherwise, any degree of separation is theoretically possible. The equilibrium composition of vapor in contact with liquid mixtures of zinc and cadmiurn at the boiling point has been determined experi-

Jan 1, 1937

By W. F. Rochow, W. C. Burke

Numerous designs of linings and accessories, including dams, lifters, and heat exchangers, contribute greatly to kiln efficiencies. Greater conductivity is achieved with basic brick than with fireclay and high-alumina refractories, depending largely upon the use of steel plates in radial joints between adjacent brick to increase heat transfer through the lining. Refractory lifters expose all portions of the load to radiant or convective heat and raise some portions to higher temperatures by cascading the load down through the path of the hot gases. AMONG the many factors involved in rotary kiln efficiency, advantageous use of refractories is of major importance. So far as kiln lining alone is concerned durability is most significant, as shutdowns for repairs are costly in fuel consumption and production losses. Aside from selection of refractories best suited to the widely varying conditions under which rotary kilns are operated, lining design and accessory constructions within the kiln are highly important. The refractory most economical for any combination of operating conditions can be selected from a wide range of alumina-silica and basic refractories, including insulating, castable, and plastic fire bricks. In several cases silica brick can be used to advantage. Alumina contents of alumina-silica refractories range from 35 to 90 pct in increments of 5 to 10 pct. In general, bricks of relatively low alumina content are best for abrasion resistance, an important property for the brick used in chain sections of cement kilns or in feed end sections of limestone kilns. High-duty fireclay bricks of approximately 40 pct alumina and 55 pct silica are used to line the intermediate zones. Super-duty fireclay brick at slightly higher cost is warranted in operation of kilns with high intermediate zone temperatures and severe spalling conditions. Alumina-silica refractories with an alumina content of 50 pct and higher, termed high-alumina brick, are available in commercial classes of 50, 60, 70, 80, 85, and 90 pct alumina content. These refractories are generally used as high temperature zone linings or placed adjacent to the basic brick-lined sections when the treatment they are required to withstand is excessively severe. Use of basic refractories is confined mainly to zones of maximum temperature and most severe chemical action. Basic refractories ordinarily employed for high temperature zone linings of many rotary kilns comprise the classes shown in Table I. Each class is peculiarly well suited to various particular combinations of working conditions. The approximate chemical analyses of these classes also illustrate differences in compositions with respect to the major components.

Jan 1, 1956

By W. H. Geis

The following pages summarize the causes that led to the suggestion of unit operation of the paloma field, the organization of com-mittees, preparation of the Paloma Operators Agreement and the reasons for rejection of the plan. Introduction Long ago an Austrian physicist observed that under certain conditions the condensation of a liquid from gaseous mixtures resulted from pressure reduction. Some 50 years later he would have known that his research was not in vain. He would have seen a group of serious operators and engineers seeking to apply that principle to a conservation . program for unitized production in the Paloma gas field—but he would also have been saddened to see that forces unsympathetic to the application of science in oil production, with little or no appreciation of modern methods and the advantages of cooperation, so far have prevented the adoption of that program. Soon after the Paloma field was discovered it was realized that all the hydrocarbons in the reservoir existed in the gaseous phase. This condition was confirmed over a large area. Therefore, if the field was to be properly exploited with the greatest ultimate recovery of condensate, the hydrocarbons in the reservoir must be produced in the single or gas phase. They must be cautiously extracted with the least possible reduction of the natural pressure. If this could be accomplished, or if artificial pressure control were utilized, the condensation and underground loss of the valuable distillate would be preventable—otherwise it would not be. Wholehearted cooperation of all oper-ators was required in order to accomplish the conservation purposes of the program. To this end the production engineers of the several companies concerned lent their time and talents. They fully investigated the physical relationships of the products within the complicated gaseous mixture, prepared extensive reports on the subject and drew up a reasonably efficient plan of operations, which now is commonly called the "Paloma Unit Plan" but actually was entitled "The Paloma Operators Agreement." All of the engineers were not in perfect agreement on all the features of the plan, or even on all the engineering principles. However, it is safe to say that on all the important or essential factors there was a unanimity of opinion, particularly as to the objectives. These were fairly simple and reduce to one controlling item, "pressure control" by cycling or recycling. Organization The principal operators initiated the program by calling a meeting of all the lessees in the area, at which an organization was perfected, known as the "Paloma Operators Committee." Various subcommittees were appointed to expedite the work, including an "Engineering Committee." These func-tioned in a businesslike manner, frequently reported to the superior committee and

Jan 1, 1942

By Joseph E. Pogue

In 1920, 531 million barrels of crude petroleum were coi~sumed in the United States. As imposing as this figure is, the fact that the domestic consumption of crude petroleum has increased at an average rate of 10 per cent. a year for the past decade is more striking. Will this rate of increase in demand continue? If so, the year 1930 will call for 1260 million barrels of petroleum—a staggering volume. On the other hand, may we expect the demand for petroleum to grow as rapidly as it did when the automotive industry was having its most phenomenal expansion? If not, to what extent will the growth of oil requirements decrease? When and to what degree will the petroleum industry become affected by the economic law of diminishing returns? Obviously, this matter requires careful analysis, especially as both national and industrial planning must be predicated upon present estimates of the requirements of the future. The purpose of this paper, accordingly, is to project, as closely as present limitations of knowledge permit, the course of the demand for petroleum in the United States over the next ten years. At first, the problem of estimating the future of a demand as complex as that for petroleum might appear insoluble. Fortunately, hon~ever, therc are several scientific methods of approaching the problem, centering around a study of rates of industrial growth, which lend considerable hope that the requirements of the immediate future in this field may be approximated with sufficient closeness to have practical value as a basis of action. Growth oF Petroleum Demand The demand for crude petroleum is the resultant of the demands for the products made jointly from this substance—gasoline, kerosene, gas and fuel oil, and lubricating oils. The demands for these have grown at

Jan 1, 1923

By G. H. Matheson, J. M. W. Mackenzie

The coal concentrates studied contained clay slimes which would not flocculate on the addition of a polymer flocculent alone. The mechanism of the flocculation process is interpreted on the basis of the flocculation of lyophobic colloids. The filtration rate characteristics are shown to deviate slightly from certain basic filtration equations. Cake moisture was shown to decrease with cake drying time and vacuum, and increase with cake thickness. Filtration is a commonly accepted method of dewa-tering the fine coal concentrates produced in coal cleaning operations. Dewatering of these concentrates, using drum or disc vacuum filters, usually presents few technical difficulties and will result in the production of a filter cake containing some 20 to 25 pct moisture. In many coal cleaning operations it is common practice to add flocculants to the coal concentrates prior to filtration to increase the filtration rate. The mechanism whereby flocculation increases filtration rate has been summarized by Gaudin,4 while Geer, et a15 have compared the effectiveness of starch and synthetic flocculants as filter aids for a variety of coal concentrates. Coal concentrates, containing appreciable quantities of expanding lattice clays of the montmorillonite-illite group, sometimes prove impossible to filter without flocculation of the pulp prior to filtration. The fine coal concentrates produced at the Newcastle washery of The Broken Hill Proprietary Co. Ltd. fall into this group. Coals mined in this district contain appreciable quantities of expanding lattice clays which break down in the washery circuit waters and, by processes of mechanical inclusion, contaminate the coal concentrate thickener feed. Despite the classifying action of this thickener, the underflow which is pumped to the filters contains sufficient clay slimes to render filtration of the unflocculated pulp impossible. Filtration leaf and plant tests were carried out to develop effective and economic flocculant combinations and to determine the filtration characteristics of the flocculated coal concentrates. The determination, by leaf testing, of the filtration characteristics, and the analysis of these characteristics in the light of the equations of Brown2 resulted in the successful trial operation of the filters in the Newcastle washq. Although the filtration characteristics are not entirely in agreement with the theoretical treatment of Brown, the equations developed made it possible to predict, from leaf tests, the effect in the plant filters of pulp density, form vacuum, and form time on filtration rate and filtrate volume. EXPERIMENTAL PROCEDURES The sample used for leaf testing was the coal concentrate thickener underflow, which in plant operations would form the feed to the two 12-disk Dorr-Oliver filters. The feed to the coal concentrate thickener comprises the undersize produced by dewatering the Diester table concentrate on 5-mm dewatering screens and the overflow produced by cycloning of the froth flotation concentrate. At the time of testing these filters were inoperative because of the difficulties in filtration, arising from contamination of the

Jan 1, 1962

The Du Pont Magazine for August and September gives the following interesting information regarding recent progress in the use' of explosives. Blasting -Clay.-"The place where I tried blasting down clay for a brick yard had been worked for some years by old-time pick and shovel method. There was a large shallow pit, irregular in shape, with a perpendicular face at one end. I put down a line of holes 3 ft. deep and 6 ft. back from this face, loading each hole with one and one-half car-tridges of Red Cross Extra 40 per cent. dynamite. The charges were connected up to a blasting machine circuit and fired electrically. "Two of these shots kept the brick yard men very busy for two days taking out the loose clay. "I am convinced that if any brick yard man will try this method he will always have a blasting machine and dynamite on hand thereafter, because it cuts labor cost almost in two to get down the clay in. this way." In some clay pits the practice is to blast a large amount of clay in the fall, allowing it to freeze and thaw through the winter. Such clay is much easier to puddle in the spring than freshly dug or blasted clay. When the clay contains stones, the blasting loosens them and makes their separation-easy. Well-Drill Holes in Quarrying.-The well drill or cable drill method of working a quarry face is now in quite common use. The use of large drills is constantly increasing among quarrymen. In fact the growing tendency is for large machinery of all kinds such as mammoth crushers, steam shovels, etc. Volume is what is wanted nowadays. The advantages of the big drill over the piston driven drill are numerous. By carrying the holes the full depth of the face the stone is loaded and treated on one working floor. It eliminates the cost of bench cleaning. Loading operations are less frequent, thus lessening the danger. Stone can be shot down in greater volume and in better shape, making it economical to use a steam shovel. No bench cleaning makes it safer for the men. It is cheaper and can be used in outlying and temporary operations where the cost of installing a power plant would be out of the question. It permits a greater spacing of bore holes and eliminates the necessity of "squibbing" or springing. In this method usually holes from 4 in. to 6 in. in diameter are drilled the full depth of the face from 15 ft. to 2,0 ft. apart, and as far back and the whole face shot down at one time. The cost of well drilling may vary all the way from 20 cents to 75 cents: per foot, and in extremely hard rocks up to $1.50 per foot.

Jan 10, 1916

By William P. Blake

The Rainbow Lode is situated at Walkerville, in the Summit Valley mining district, Silver Bow County, Montana Territory, about one mile from Butte City. It was so named ill 1876 by Mr. J. E. Clayton, in recognition of the broadly-sweeping curve of the outcrop across the rounded surface of the eastern slope of a granitic mountain, at an elevation of about 6000 feet above the sea-level. It is on the western side of the range which divides the waters of the Missouri from those of the Columbia. History.—The history of the district is an instructive one. The water-courses and flanks of the hills were worked for years for placer gold. Millions of dollars' worth of low-grade gold have been washed out of the surface gravels below the veins of the district. Missoula Gulch and Silver Bow creek, just below Butte, are noted for their rich placers, and they continue to yield largely, producing within narrow limits from $50,000 to $100,000 dollars' worth of golddust yearly. It is ragged vein-gold, and evidently is near its parent source. It is no doubt derived from the disintegration of the veins of the district, and this conclusion was soon forced upon the miners. The veins which were seen outcropping boldly upon the slopes above them were located, and prospecting commenced. These outcrops were found heavily stained and blackened with oxide of manganese, and were porous and honey-combed in places, showing that the quartz was formerly filled with pyritous ores, and that these ores had decomposed and dissolved away, leaving, however, portions of the precious metal behind, especially at and near the surface of the ground. Assays of the croppings gave variable and often contradictory results; but the fact. that these were the outcrops of lodes bearing gold and silver in depth was patent to any experienced observer of mineral veins. The lodes of the district were first brought prominently to notice by Mr. Clayton in 1876, and in October of that year the Alice mine, upon the central portion of the lode, was opened by Mr. Marcus Daly, now so well known as the superintendent of the Anaconda Copper mine, upon another extremely interesting lode, in the same region.

Jan 1, 1888

By C. G. Dunn

NUCLEI that are formed during the recrystallization of a grain following plastic deformation generally have orientations that differ from the original. This aspect of recrystallization may be described in terms of orientation changes. It was shown previously, in an investigation on recrystallization in silicon ferrite,1 that the observed orientation changes were highly improbable on a chance basis, and that some mechanism must be involved. Analysis showed that the data could be satisfactorily classified into the smaller of two subclassesf of the 36 third- order twin transformations. No attempt was made at that time to classify the data within the special class of 12 third-order twin transformations, although results did indicate a greater probability for some of them to occur. A classification of this type would be more valuable, of course, with more data on orientation changes per old deformed grain. The present work fulfills this condition to some degree and also extends the scope of the investigation to include the effects of original orientation and the amount of plastic deformation. The effect of original orientation is of considerable interest because of the known effects of orientation on plastic deformation, particularly with regard to degree of fragmentation and the formation of de- formation bands, and because the orientations produced by deformation should influence the orientations obtained through recrystallization. Barrett and Levenson2 reported that single crystals of iron deformed in the range 82 to 97 per cent could be put into three general classes; namely, crystals in class I maintained a reasonably sharp single orientation, those in class 2 transformed into two distinct orientations, and those in class 3 changed into a large number of major and minor orientations. Something similar would be expected for silicon ferrite crystals, and verification of this for a few cases of types class I and class 2 deformation has been reported elsewhere3 for single crystals of silicon ferrite cold-rolled in the range 10 to 20 per cent. As an example of class 2 deformation, it was shown that a crystal of silicon ferrite cold-rolled in a {110} plane in a < 100> direction developed two layers, or deformation bands differing in orientation. When this happens it is possible to etch away one band and leave a single structure for use in studying the orientation changes that occur during recrystallization. when preferred crystal orientations are obtained in recrystallization, it is notparticularly necessary to evaluate groups of common orientation, as was done previously (ref. I, Table 6); but an

Jan 1, 1946

Open pits and quarries are the major sources of all hard rock tonnages mined today. Normally, ore is fractured from the pit bench face by blasting and then truck-hauled to a primary crusher on the pit rim for conveying to the concentrator; overburden (or waste) is generally truck- hauled from the pit to dump areas. This system of truck haulage of blasted ore and waste accounts for some 25 to 50% of total mining costs in a typical open pit operation and commonly is the largest single cost factor. In an effort to reduce these costs mining companies are continually replacing their older and smaller trucks with larger ones and at the same time are studying conversions to conveyor haulage, since this method of transport seems to offer possibilities of lower costs per ton of material handled. In these studies it seems logical to consider installing these conveyors as close as possible to the mining face for maximum use of conveyors and minimum use of trucks, since a conveyor is much less labor intensive than a trucking system. However, direct loading onto a conveyor near the retreating bench face is impractical because of excessive lump size. Consequently, it is conventional practice to load the blasted rock into trucks at the face for haulage to the crusher. After crushing, the rock is fed onto a conveyor. The closer the crusher is to the mine, or if it is in the mine, the shorter the truck haul and the greater the potential for cost saving. At first appearance, in-pit conveying might seem to be an obvious solution, yet many mining companies have considered such a move while few have implemented it. To determine why, it is necessary to consider the factors influencing such a decision. A conveyor system tends to be capital intensive but can have a lower operating cost per ton than trucks. Trucks, on the other hand, tend to cost less to buy but more to operate; thus, economics tend to favor the conveyor if it can be operated close to capacity and if a sufficiently large tonnage can be passed over the system to mitigate the effect of its high capital cost. In a typical hard-rock, open-pit mine it is necessary for a variety of reasons to mine several faces of both ore and waste at the same time; and any mining system must have sufficient flexibility to permit loading from one face or another at short notice. This makes it impractical to place small mobile crushers and their consequent network of conveyors at each working face. To date no alternative has been found to using trucks for bringing all rock of the same class to some convenient marshalling point from which it may be crushed and conveyed from the pit. Another advantage of trucking when compared to conveying is flexibility. Many mines wish to deliver their shot-rock to different locations, depending on the mineral content. For instance, a typical copper mine may have to simultaneously mine milling ore, leach ore,

Jan 1, 1978

By E. H. Kelton, R. D. Grissinger

In designing structural members of steel and some other materials the design engineer has available recognized values of elastic modulus and safe working stress that may be substituted in well-known engineering formulas to give him desired cross-sectional areas and deflections for a particular part. Zinc, on the other hand, has no generally recognized modulus. It flows under continuously applied loads. Therefore, the designer of structural members must use a range of working stresses depending on the continuous load and the amount of permissible distortion. The only method of obtaining these values is by creep testing. Creep testing of zinc has been carried on for some 20 years by this laboratory, covering a wide range of zinc and zinc alloys. Types of test included tension, compression, and simple and cantilever beams at temperatures ranging from o to I50°C. Specimen conditions ranged from as-cast or as-rolled to accelerated aged in steam or dry air. Effects of plating were investigated also. It is not the intention of this paper to expound all these factors but rather to present the final data on well-known zinc die-casting alloys and to suggest means of applying these data to engineering design. Early Work In the early work on creep testing of zinc, the direct-loading tension method was used. However, direct loading of die castings was unsatisfactory because of the high loads required. For instance, a standard die-cast tension bar having a cross-sectional area of about 0.049 sq. in. would require a direct load of about 1000 lb. for a unit stress of 20,000 lb. per sq. in. Also, tests were made at nominal room temperature, but normal variations caused fluctuations greater than those due to experimental error or other causes, so that control of this variable within ±1/2°C. seemed essential. These two factors led to the development of an apparatus described by J. Ruzicka,&apos; in which the specimens were loaded by means of a lever and were held at constant temperature by means of an oil bath. While Ruzicka&apos;s apparatus yielded excellent check results, it seemed desirable to have some setup by which literally hundreds of die-cast specimens could be tested at the same time. This would permit the conducting of a number of low-load tests designed to run 10 years or longer and still leave capacity for current high-load work. Beam testing in a constant-temperature room was the answer. Test Method Preliminary work indicated that die-cast beams of various lengths and cross scctions yielded the same result within reasonable limits regardless of whether they were tested as simple beams, uniformly loaded beams, or cantilevers. Accordingly, the simplest type was adopted. This was a,

Jan 1, 1945

By H. H. Reamer, B. H. Sage

The formation volume and the relative volume of the liquid Phase of mixtures of Condensate and gas from five different parts of a field in the Louisiana area have been established experimentally. These studies included gas-condensate ratios as high as 25.000 cu ft/bbl at pressures up to 5,000 psi. The gravities of the tank condensates were between 53.9° and 63.9° API. The compositions of the condensate and gas samples inves-ligated are presented in tabular form. The formation volume. the relative volume of the liquid phase. and the specific volume of the mixtures are available. A rough correlation of the formation volume as a function of pressure. temperature, and gas-condensate ratio has been presented. This correlation i-considered applicable only to the range of conditions covered in this investigation for systems of similar nature and com-position. INTRODUCTION Often a knowledge of the influence of temperature. Pres sure, and relative quantities of condensate and gas upon the volumetric behavior of fluid*. from a given field has been employed in estimating the Conditions existing in the reservoir. The early work of Beecher and Parkhurst&apos; and the more rrcent Studies of the Dominguez&apos; and San Joaqnin Valley Field;: are examples of experimental studies of this character. Correlation of the volumetric behavior of naturally occurring hydrocarbon mixtures has Proved To be feasible&apos; . at low gas-conden-sate ratios-; for fluids*. from a single geographic area. Progres 5 is being made in the Prediction of the volumetric behavior of distillate systems at high gas-condensate ratios and pressure.. However. the estimation of the retrograde". &apos; dew-point pressure still remains uncertain and probably can best be established by experiment. For this reason it appears of interest to make available experimental information about the volumetric behavior of mixtures of condensate and gas from five different part.; of a single field. This material shows a rough similarity to data for mixtures of condensate and gas from San Joaqnin &apos; Valley Fields. In the present paper. 110 attempt has been made to coordinate the available information on tbe volumetric behavior of fluids from condensate fields. It appears hopeful that progress can be realized by the utilization of recently developed equa-tions of state.!&apos; However. the primary problem in any such correlation is the proper identification of the components and constituents of naturally occuring systems. Additional experimental information may be required to permit the determination of the values of the constants of the equation of state for References given at end of paper. Manuscriptt received in the office of the Petroleum Branch June 11. 1951. *For present purposes low gas- condensate ratios will he considered as those below 3,000 cu ft/bbl, and the region of high gas-condensate ratio will be limited to compositions containing more than 5,000 cu ft of pas per bbl of condensate. Mixtures Containing between 3,000 and 5.000 CII ft OF gas per bbl will be considered of intermediate gas-condensate ratio.

Jan 1, 1952

By H. H. Reamer, B. H. Sage

Attempts have been made to predict the volumetric and phase behavior of naturally occurring hydrocarbon mix-turesl-6 but these methods have not been extended to the higher pressures and tem-peratures that are currently encountered in some producing formations. Furthermore, the methods of prediction at present avail-able have not been tested in a sufficient number of cases to ensure their applica-bility to all naturally occurring hydrocar-bon mixtures, even at the lower pressures and temperatures. For these reasons the behavior of a number of hydrocarbon mix-tures from a field in which the subsurface pressures are above 4500 lb. per sq. in.t and the temperatures are in the neighbor-hood of 250°F. was investigated. Method The objective of this program was to determine the volumetric behavior of ma-terial as it existed in the reservoir as a function of pressure, temperature and com-position. Strictly speaking, this cannot be accomplished in any simple fashion. How- ever, the variations in composition that are encountered within a producing reservoir may be approximated roughly by means of mixtures made up of two arbitrarily chosen constituents. Experience indicates that the liquid and gas phases from a high-pressure gas trap afford a simple source of material for this purpose. Throughout this discus-sion the samples of the gas phase and liquid phase from the production trap will be called the "trap-gas sample" and the "trap-liquid sample," respectively. The volumetric behavior of both of the trap samples was determined throughout the temperature interval between 100" and 250°F. at pressures up to 5000 lb. per sq. in. In addition, the behavior of eight different mixtures containing varying proportions of the two trap samples was studied throughout the same temperature and pressure intervals. The experimental results yielded information concerning the specific volume of the material as a function of pressure, temperature and the relative quantity of the trap samples. The relative amount of each of the paraffin hydrocarbons of lower molecular weight than n-hexane was determined for each of the trap samples. In addition, the specific weight, viscosity and average molecular weight of the hexanes-and-heavier fraction of the trap-liquid sample were determined as well as similar information for each of five fractions separated from this material by distillation. From these data the weight fractions of each of the components from methane through pentane were determined for the trap samples and eight systematically chosen mixtures. Materials The gas and liquid samples were obtained from the production trap of a well in the Rio Bravo field in California during the fall of 1939. Information concerning the condi- 70

Jan 1, 1941

By Tracy L. Atherton

The mapping of slant-hole oil fields is complicated by the fact that relationships between wells are subject to variations in three dimensions and are not readily adaptable to representation on a plane surface. Formalized perspectives usually expand into an undecipherable maze of lines and peg models with the necessary supporting dividers serve only to awe the beholder with their perplexity. The usual compromise arrived at is a plotting of the projection of the courses of all of the wells in the field onto a horizontal plane (Fig. I). These complicated plots, when used in conjunction with the individual vertical projections of the wells, heretofore have been the most practical foundation for the study of general field problems. This method has many shortcomings, however, which arc not found in the recently developed straight-hole equivalent projec-tion method. The new method supplies a series of maps similar to the type now in common use in straight-hole fields. It is remarkably simple to use and supplies a ready check on clearances between wells. Perhaps the method can best be understood if the steps that led to its development are described. Common practice of oil-well surveyors is to supply the owner with a tabling of the survey and a plan view plotted against the true meridian. If a vertical projection is plotted, it is usually plotted separately and shows vertical depths against the projection of the stations along a section line joining the top and bottom of the hole on the plan view. A more practical method would be to plot the section line of the plan parallel to the abscissa of the vertical projection (Fig. 2). If this is done, any line parallel to the "base line1&apos; will pass through the points on each projection that represent a single point in the hole. Another very useful graph, which the well surveyor could provide, would be plotting of vertical depths against measured depths. Fig. 3 illustrates the next step facilitated by this form of plotting. The lines designated "well A" represent the proposed course of a hole to be drilled. Superimposed on the drawing, in its proper relative position, is the plan view and a portion of the vertical projection of a present producer, well B." From an inspection of the plan view we arrive at the correct conclusion that the only indicated possibility of collision is at the point of crossing of the wells on the plan view. Referring to the vertical projection, note that the vertical depths of stations on B, in the vicinity of the crossing, are plotted on the same plane of projection as A. The clearance is the indicated distance between the two vertical sections measured along the parallel to the "base line," which passes through the point of intersection of the plan view. Repeat this process for the other wells crossing the proposed course of A on the plan view and you have a preliminary check of clearance for the proposed course. A similar comparison of crossings on the vertical projections of all >

Jan 1, 1941

By E. W. McAllister

The decision of the California Oil Umpire&apos;s&apos; office to accept well potentials established from subsurface-pressure data has brought to the attention of many operators for the first time the application of such data to production problems. This paper reviews the development and application of subsurface-pressure data in kettleman Hills, where these data have been used in production work since 1932. The Kettleman Hills field was discovered in October 1928. The first subsurface-pressure surveys were made early in 1932 and by the middle of 1933 the two major operators in the field were making routine pressure runs in thcir respective wells. Shortly therefter, these companies agreed to exchange pressure data, and later a third company entered into the agreement. This made it possible to analyze the effects upon the reservoir pressure of past production practices, which are discussed in the latter part of the report. It is interesting that many of the applications of subsurface-pressure data discussed herein were anticipated by C. L. Clark and C. B. Kimberlint in a report2 dated March 1933. PRODUCTIVITY Index In the majority of individual well problems involving the use of subsurface- pressure data, it is necessary to use a factor known as the "productivity index," which indicates the ability of a well to produce and represents the number of barrels of oil or oil and water per day that will enter the well bore for each pound per square inch pressure drop made opposite the producing interval of the well. The productivity index may be determined from pressure and production data for one or more rates of flow and a static or shut-in pressure survey or from production and pressure data for two or more rates of flow. Productivity indices may be based upon either net oil or total fluid production. All indices referred to in this report are based upon net oil. The value of the productivity index for Kettlcman Hills wells decreases generally with time and it is not uncommon for the index to vary in value at any specific time fur various rates of flow. The decline of the productivity index may be attributed partly to the loss of reservoir pressure. As the reservoir pressure decreases, gas originally in solution is released from the oil, congesting the flow of fluids through the formation and increasing the viscosity and surface tension of the oil; thus the flow resistance of the fluids through the formation is increased, resulting in a decrease of the productivity index. For convenient reference, the productivity indices for each well are plotted against time and a curve is drawn through the points showing the trend of the average index value. Plotted on Fig. I are index values for five

Jan 1, 1941

By Howard C. Pyle, John E Sherborne

Core analysis is a recent development in the field of petroleum technology. The earliest work on this subject was done in connection with evaluating and planning secondary oil recovery by water-flooding. Present-day analysis of sands of flush fields requires new and independent interpretations of the data provided by cored material. Particular attention is being paid to the development of rapid, routine methods for measuring physical characteristics of sandstone, such as permeability, porosity and grain size, as well as the sand&apos;s fluid content. Permeability may be defined as the fluid-passing capacity of a rock. For a sandstone to be permeable it must be possible to pass a measurable quantity of fluid through the material in a finite period of time. The common unit of permeability is the darcy, which may be defined as the rate of viscous flow, in milliliters per second, of a fluid of one centipoise viscosity through a porous medium having a cross section of one square centimeter, under a pressure gradient of one atmosphere (76.0 cm. Hg) per centimeter.&apos; For convenience the subunit millidarcy, or one-thousandth darcy, is often used. Porosity is defined as the fluid-containing capacity of a rock and is usually expressed as a percentage ratio of the total pore volume to the rock or bulk volume. Since measurement of only the effective or communicating pore volume is often made, porosities are distinguished as total or effective.2,3 Net effective porosity is defined as the net pore volume available for oil and gas. Oil and water content of sand is measured and expressed either as the percentage saturation of the total pores or of the bulk rock. The oil content may also be expressed as the percentage saturation of the net effective pores. In connection with water-flooding, methods of core analysis were developed to furnish data that could be used in determining the quantity of recoverable oil14-6 and the probable rates at which various sands or divisions of a sand open to the wells would take water or produce oil. In flush fields, the analytical data are used to predict the productivity of a cored interval. They indicate the presence of oil, gas and water and may

Jan 1, 1939