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By D. M. Clippinger, J. J. Eidel, J. E. Frost

At Ithaca Peak, one of three peaks situated on Duval Corporation's Mineral Park property, a 'Single pulse of quartz monzonite magma intruded the isoclinally folded Precambrian Cerbat complex consisting of schist, quartzfeldspar gneiss, and amphibolite. The magma reacted with the Precambrian rocks, yielding a quartz-diorite rim. As the magma crystallized within the rim, it produced, progressing in'ward, annular bodies of quartz monzonite porphyry, quartz porphyry, and a distinctive quartz porphyry containing abundant podiform, tabular, and irregular quartz masses. These quartz masses are spatially associated with discontinuous crenulate and tabular quartz veinlets. Following crystallization, the Ithaca Peak stock and part of the surrounding Cerbat complex were fractured, producing a stockwork of predominantly northwest and northeast-trending fractures. The stockwork was then mineralized during a period of decreasing temperature by: ( 1) quartz-pyritechalcopyrite veinlets without distinct selvages and with distinct alteration envelopes in which orthoclase was altered to quartz and sericite; (2) quartz-pyrite-chalcopyrite veins and veinlets with distinct selvages and without distinct alteration envelopes; and (3) pyrite-chalcopyrite- galena-sphalerite veins. The Ithaca Peak stock was pervasively sericitized or argillized. The Mineral Park property is surrounded by a zone of propylitization Alteration and mineralization are coextensive in space and were, at least in part, coincident in time. The Mineral Park property possibly was elevated and exposed twice prior to its present exposure. The protore has been enriched by a factor of three. The Ithaca Peak supergene ore body is conformable with present topography and lies above the present water table. The shape of the ore body was controlled by erosion and oxidation of the previously enriched mineralization. Hematite, goethite, and jarosite present at the surface indicate a high primary pyrite environment, but it is possible to recognize that a small proportion of veins and veinlets contained greater amounts of chalcocite and chalcopyrite than pyrite. The igneous facies on Ithaca Peak are the products of differentiation within a solidifying rim according to Bowen's Reaction series. The innermost facies contain more quartz and orthoclase than the outer facies. Late magmatic quartz in the case of Ithaca Peak contains small amounts of pyrite and molybdenite. It is suggested that this quartz-sulfide mineralization, may also have been the product of differentiation the product of differentiation, may indicate that the later hydrothermal mineralization may also have been the product of differentiation.

Jan 1, 1968

By E. J. Rapperport, J. P. Pemsler

The thermodynamic activities of zinc in six solid solution Cu-Zn alloys ranging from 5 to 35 at. pct Zn were determined experimentally in the temperature range 400° to 600°C. This low temperature investigation was canducted in order to evaluate techniques developed to utilize the inherently high sensitivity of atomic absorption flocesses in the measurement of thermodynamic activities. Analytical expressions ,for the activity and actizlity coeflcient are given for the six alloys in the temperature ranges investigated. RELATIVELY few experimental methods are available for investigation of thermodynamic activities of alloys, especially in the solid state. The techniques most frequently used have been the electrochemical potential and the effusion methods, both of which have severe limitations in many instances. It is therefore desirable to expand the ability to perform such measurements in order to obtain new information as well as to provide an additional independent verification capability. In this work, we present a significant improvement in the spectrophotometric method for sensing small vapor pressures in static absorption cells. Similar techniques have been used previously;1"5 however, applications had been limited to relatively high pressures, often greater than 1 torr. Prior investigators have, for the most part, used broad spectral sources such as xenon or mercury lamps, and high intensity arcs. Hollow cathode sources were first suggested in 1956 6 and were used soon afterwards.4'5 These sources offer significant improvements in sensitivity and freedom from interfering spectral lines.'-' EXPERIMENTAL High purity zinc was obtained from Cominco Products, Inc., and copper from American Smelting and Refining Co. Both elements were of 99.999 pct purity. Copper-zinc alloys were vacuum melted in a high fired carbon crucible with each alloy pulled from the melt as a 4 -in. diam bar. The bars were swaged to -1/4 in. rods and vacuum annealed for 160 hr at 800° + 1°C. Samples for gross chemical analysis were taken at intervals along the length of the rods to ascertain the axial zinc gradient. Electron microprobe analysis of homogenized specimens indicated that the alloys had uniform compositions over their cross sections on a macro (200 p) and micro (1 u) scale to better than *1 pct (20) of the gross composition. This tolerance was determined by counting statistics, rather than assured composition fluctuations. All SiO 2 windows were high-ultraviolet-transmission grade to minimize intensity losses. Silica absorption cells were scrupulously cleaned consecutively in organic solvents, dilute HF, and distilled water before use. The empty cells were then flamed while under a dynamic vacuum, cooled, and removed to an argon-filled glove bag. Alloy pieces were cut and filed in the glove bag to produce fresh surfaces, and then loaded into the cells. The loaded cells were temporarily sealed, removed from the glove bag, reevacuated to 10-5 torr or better, and permanently sealed. The instrument used is schematically shown in Fig. 1. The spectral emission from a commercially made hollow cathode lamp (A) of a selected element is focused through an absorption cell (B) inside a well-controlled furnace (C). The intensity of the transmitted beam is measured using the spectrometer* (D) 'Techtron model AA4 atomic absorption spectrometer. which contains a grating (E) that disperses the light prior to impingement on the photomultiplier (F). The monochromator grating is adjusted so that only the wavelength of interest is measured. The power supply delivered an interrupted voltage to the lamp, causing a chopped radiation output to be transmitted. The detector read only the intermittent component of radiation incident upon it, so that all continuous noise signals (furnace radiation, and so forth) were eliminated. Three recording thermocouples contained in the muffle furnace were positioned along the length of the absorption cell: one at each end and one at the center. An effort was made to keep the ends of the cell several degrees hotter than the center to avoid window condensate. Appropriate thermal corrections were then necessary to relate cell pressure to radiation attenuation. Water-cooled heat shields, as shown in Fig. 1, were found to aid signal stability by protecting the hollow cathode and the photomultiplier from furnace radiation. The furnace had a 2-in. diam muffle, Kan-thal wound, with SiO 2 windows at its ends to minimize convective effects. The hollow cathode radiation was masked and focused to form a conic beam that was a maximum of { in. diam within the furnace. Thus, the 1.5 in. diam absorption cell easily contained the entire beam. The furnace was mounted on ball-bearing slides with positive positioning detents. This arrangement allowed the removal of the entire furnace assembly from the radiation path, position [I], Fig. 1, so that frequent sampling of the unattenuated beam intensity could be obtained. In all cases the beam intensity was kept constant to 0.1 pct as judged by readings taken immediately before and immediately after data collection. Only data for absorptions of less than 80 pct were utilized, as systematic deviations from linearity were found for greater absorptions.

Jan 1, 1970

By JESSE L. MAURY

DEVELOPMENT of new gold mines in Canada since the price of that metal was increased in 1932 and 1933 has been of interest and importance to many of us. The day-by-day story has given an impression of aggressive effort and enough good luck so that the spirit of enterprise has been encouraged. It is the purpose of this article to report the results of a statistical appraisal which give emphatic numerical confirmation to this impression, together with certain side lights on the costs of development and equipment of new mines. The data presented have been taken from all readily available published sources up to the close of 1938 and are representative of that year. A. B. Bower did a large part .of the spadework and Weston Thomas offered many helpful suggestions.

Jan 1, 1939

By R. L. Jones, H. Conrad

The effects of gain size on the room-temperature tensile properties of commercial(A- 70)-purity and iodide-purity titanium were investigated by concurrent tensile testing and thin-foil electron transmission studies. The mechanical tests showed that the effect of grain size on the yield, flow, and fracture stresses could be expressed by relations of the Hall-Petch type. The magnitude of the grain size effect on the yield stress was larger for commercial-purity than for high-purity titanium, but in both materials it was intermediate between that typically observed for fcc and for bcc metals. The effect of strain on the gain size sensitivity of the flow stress was found to reflect the grain size dependence of strain hardening. The electron transmission study indicated that the tensile behavior could be accounted for in terms of the dislocation densities and distributions formed during deformation. It was concluded that the effect of grain size on strength could be attributed to a relationship between grain size and the dislocation densities generated in initiating and sustaining plastic flow, the difference in stress levels being due to strain hardening. The relationships between recrystallized grain size, uniaxial tensile properties, and dislocation substructure have not been explored in any detail for a titanium. With titanium and its alloys finding increasing applications in aerospace systems, such information has become essential. The research described in this paper had two objectives: first, to document the effect of grain size on the yield, flow, and fracture stresses of unalloyed a titanium by the tensile testing of recrystalliied specimens at room temperature; second, to attempt an interpretation of the mechanical test behavior in terms of the dislocation structures formed on deformation, as observed by transmission electron microscopy of thin foils prepared from deformed tensile specimens. The observations reported here are restricted to room-temperature deformation; the effect of temperature on the yield and flow stresses of a titanium and the athermal nature of the contribution of grain size to the flow stress have been discussed elsewhere.1"3 EXPERIMENTAL DETAILS Two purity grades of unalloyed titanium have been investigated: Crucible Steel A-70, a typical commer- cial-purity product, and a high-purity iodide grade supplied by the Foote Mineral Co. Chemical analyses for interstitial impurity contents are given in Table I, together with values for the total interstitial atom fractions in terms of oxygen equivalents, which were calculated by the method outlined previously.4 ,5 According to the manufacturer's nominal analysis, the A-70 grade also contains about 3700 ppm of Fe. The A-70 grade was supplied as 1/4-in.-diam centerless-ground rod. The iodide grade was supplied as crystal bar which was consolidated to approximately 1/4-in.-diam rod by a single, rapid, molten zone pass, using electron beam heating. The 1/4-in. rods were cold-swaged to 0.078-in.-diam wires and 2-in. lengths were recrystallized in a vacuum of -5 x 10-5 torr, giving grain sizes in the range 0.8 to 30 . The thermal treatments and resulting grain sizes are summarized in Table 11. Since there was in no case any obvious sign of a bimodal dis tribution of grain sizes, the grain size values quoted in Table I1 are those obtained from mean linear intercept measurements involving >I00 grains. For the two coarse grain sizes the measurements were made using conventional optical techniques. It was noted during these determinations that the etchants used (10 pct HF; 30 pct HN03; 60 pct H20 and 2 pct HF; 2 pct H202; 96 pct H20 were both tried) etched grain boundaries very nonuniformly and optical polarization effects had to be employed to reveal boundaries which might otherwise have been missed. It was found that this problem became more acute with the finer grain sizes as the usefulness of polarization diminished.

Jan 1, 1970

By Y. C. Liu

THE existence of mechanical twins in bcc metals has long been known. With recent intensive interest in the mechanism of twin formation and its role in plasticity and crack initiation, a study of the general Characteristics of twin intersection appears pertinent. The scope of the present note will be limited to the crystallography of the twin intersections of (112) twins, without consideration of its mechanism, movement of atoms, crystal structure, or the strain energy involved at such an intersection. The twinning elements of (112) twins are considered to be K1 = {112}, n1 = (111) and K2 = {112}, n2 = (111) with a twin shear of 0.707. The crystallographic features of twin intersections have been worked out in detail by Cahn.1 The present work applies the general principles postulated by Cahn to the intersections of (112) twins. The basic conditions for the twin intersection are: 1) The trace of crossing (A) and the secondary (C) twins in the planes of the crossed twin (B) must be parallel. 2) The direction (n1) and magnitude (s) of shear must be identical in the crossing and secondary twins. Also the sense of shear must be the same. These two conditions have to be fulfilled in order to maintain geometrical continuity at the twin interfaces. Fig. 1 shows the perspective representation of how these two conditions are fulfilled at the intersection. This type of intersection will be named Type-I. It is the purpose of this note to point out the existence of another type of intersection, Type-II, as shown in Fig. 2. In this type of intersection, the crossing twin A remains straight and the crossed twin B has been bent. The two conditions laid down by Cahn must also be met. This leads to the following corollary conditions: 1) The interface between twins B and C must be parallel to the twin habit of crossing twin A. 2) n1c must be parallel to n1A. 3) The twin shear (s) of twin C must be exactly equal to and in the same sense as that of crossing twin A. Thus, in order for the Type-II intersection to take place, the twining elements of secondary twin C must fulfill the above three conditions with respect to crossing twin A. Let K1 of crossed twin B be (112). All indices of the matrix can therefore be converted into new in-

Jan 1, 1963

By Joseph A. Holmes

I. INTRODUCTORY. THE plans for the investigation of fuels and structural materials now being conducted by the Technologic Branch of the United States Geological Survey were, before being decided upon by the Director of the Survey, submitted for consideration to the National Advisory Board, upon which there are nine representatives from the membership of the American Institute of Mining Engineers, viz.: Messrs. John Hays Hammond, Robert W. Hunt, B. F. Bush, and E. V. d'Invilliers (representing the Institute); Messrs. Julian Kennedy and C. S. Robinson (representing the Iron and Steel Institute); Dr. Charles B. Dudley (representing the American Society for Testing Materials); Mr. F. H. Newell (representing the U. S. Reclamation Service); and Dr. Richard Moldenke (representing the American Foundrymen's Association). It seems fitting, therefore, that a report of these investigations of the past three years should be submitted to the Institute for publication in its Transactions. The above, together with other representatives of the national engineering societies and allied organizations, were invited by President Roosevelt to serve, along with the Chiefs of the several Government Bureaus who have charge of public works and large. fuel purchases, on the National Advisory Board to give advice concerning these investigations. The appointment of this National Board grew out of a wish on the part of the President, the Secretary of the Interior, and the Director of the Geological Survey not only that the appropriations for these investigations be expended in a manner most beneficial to the several branches of the government

Jan 7, 1908

By K. A. Pauly

(Wilkes-Barre Meeting, June, 1911.) COMPRESSED air has been and is still very extensively used in connection with mining-operations, but its application in the past has been almost entirely confined to supplying power to underground machinery. Its introduction was due to the difficulty of taking care of the steam which is exhausted underground, rather than to any advantage in efficiency to be gained by its use. The ease with which electric power may be carried to the remotest parts of the mine and the high efficiency of the electric motor have long been appreciated by mine-operators, and electric power is now extensively used underground in the more recent developments, while many of the compressed-air engines in the older workings are being rapidly replaced by electric motors. Recently, however, it has been suggested to use compressed air for driving the large shaft-hoists, the air for the engines being supplied by electrically-driven compressors, and an installation of this character is being erected at Butte; Mont. It is the object of this paper to compare the compressed-air system of hoisting with the various electrical systems, from the stand-points of first-cost and cost of operation. However, before entering into a discussion of the various systems, it will be well to consider briefly the conditions affecting the choice of a system of hoisting in which electricity is the ultimate source of power. The power required by a mine-hoist is extremely intermittent and fluctuates between very wide limits, the all-day average consumption of power not exceeding from 5 to 15 per cent. of the maximum demand during hoisting. The cost of supplying power for such a fluctuating load is necessarily higher than that for supplying an equal amount of

Dec 1, 1911

By Edward W. Parker

At the Cleveland meeting of the Institute, October, 1912, I had occasion to call attention to the general though erroneous impression that the principal mining activities of the United States lie west of the 100th meridian of longitude. Few, I believe, realize that the States east of the Mississippi river, which comprise only 28.8 per cent. of the total area of the United States, exclusive of Alaska, contribute about two-thirds of the total mineral production, computing by values. In 1910 the percentage of the production credited to the Eastern States was 67; in 1911 it was 65. When I have, with becoming modesty, ventured to speak of these comparisons, I have usually been met with the rejoinder, " But you include coal." I surely do, for whereas coal (m petroleum, as natural gas, as limestone) is not in the strictly technical definition of the word, a " mineral," it is legally mineral, is certainly a mineral substance, and contributes by far the largest tonnage and approximately one-third of the total value of all mineral products. The production of coal-mines in 1911 weighed approximately 500,000,000 tons. In 1912 it exceeded that record by nearly, if not quite, 50,000,000 tons. According to H. D. McCaskey, of the U. S. Geological Survey, the total weight of all the metallic ores mined in the United States in 1911 was 105,000,000 tons (a little more than one-fifth that of coal). In 1910 Mr. Lindgren estimated the total weight of all metallic ores at 120,000,000 tons. The products of the quarries, clay-pits, oil-wells, phosphate-mines, and other non-metallic products, taken all together, did not in 1911 weigh in excess of 300,000,000 tons, so that the output of coal exceeds by 25 per cent. the combined tonnage of all other mineral products. The coal-mines give to

Jan 1, 1914

By R. V. Smith, E. J. Dewees, R. H. Williams

Before this paper was presented, the terms "f" and "v1/f in flow equations had been called "friction coefficient" and "friction factor," respectively. However, many authors have used the names for the terms interchangeably, with the result that considerable confusion has existed in the literature on flow of fluids. In an effort to establish a clear and concise terminology for these terms, the authors have designated f as "resistance coefficient" and dm as "transmission factor." Transmission factors for the flow strings of gas wells were determined by tests on wells in six fields of Oklahoma, Texas, and Louisiana. Data were collected on 14 gas wells while gas was flowing through 1 1/4, 2, 21/2, and 3-in. tubing and 51/2 and 7-in. casing. The transmission factors developed from these data were found to follow the resistance equation published by Nikuradse1 for turbulent flow in "rough" pipes with an average absolute roughness of 0.000,65 in. This average absolute roughness is believed to be representative generally of the flow strings of gas wells with the exception of those that have been exposed to corrosion or other conditions causing undue roughness. Also, use of an absolute roughness of 0.000,65 in. probably will result in transmission factors that are more representative of gas-well conditions than those in common use today, provided that the transmission factors are calculated by the methods outlined in this report. The authors believe that use of these transmission factors will permit calculation of more accurate subsurface pressures in gas wells than those in use today. Engineers use transmission factors in flow equations to compute subsurface pressures in flowing gas wells from measured wellhead pressures. These subsurface pressures are necessary for determining the productivity of gas wells from "back-pressure" tests. The methods of calculating pressures in flowing gas wells, as outlined by Rawlins and Schellhardt2 in Bureau of Mines Monograph 7, are based on the transmission factors in the well-known Weymouth formula" Natural gas engineers have realized that errors introduced by using transmission factors as given by the Weymouth formula are relatively unimportant in testing low-capacity gas wells; but they also know that such factors are important considerations in testing large-capacity wells. Accordingly, the research described in this report was undertaken to fulfill the need for more accurate means of calculating subsurface pressures in gas wells. This report is part of the Bureau's study of the flow of natural gas through pipe and commercial pipelines. Several of the conclusions regarding flow in the flow strings of gas wells were influenced by the results of the study of flow in horizontal pipelines. These instances are mentioned in the text of this report. METHODS OF COMPUTING TRANSMISSION FACTORS Methods and procedures for computing transmission factors for turbulent flow in circular pipes from test data taken on gas wells have been derived and explained in detail in a paper by Smith4. As these methods were used to calculate the transmission factors presented in this report, a summary is included. Starting with

Jan 1, 1955

By Tomek Ulatowski

INTRODUCTION In 1974, Industrial Miners Mexico, S.A. (IMMSA), agent for the borrowers, was the largest privately-held mining, smelting, and refining company in Mexico (accounting for 32% of Mexico's nonferrous metal and coal production in 1974), the fourth largest company in terms of sales, and the second most profitable company in Mexico, excluding government wholly-owned and operated industries. The company was engaged in the mining, smelting and refining of coal, copper, fluorite, gold, lead, silver, zinc and related by-products for domestic consumption and export. A combination of favorable factors led IMMSA to propose an investment plan amounting to US$286 million for 1974 through 1978, of which US$150 million was to be financed. These factors included: Substantial profits in 1973 and 1974 Positive near-term outlook for metal prices Success of the reinvestment program in increasing productivity Substantial additions to proved reserves during 1973-1974 and Fiscal incentives provided by the Mexican government to stimulate investment in the mining industry. The primary purpose of the investment program was to construct a new electrolytic zinc refinery and to expand and modernize many of the company's existing mining and refining facilities. THE BORROWER Company History Compania Miners Mexico, S.A. was incorporated in the city of Monterrey in 1918 as a wholly-owned subsidery of ASARCO Inc. (formerly American Smelting and Refining Company, New York) for the purpose of mining and processing non-ferrous metals and related products. In compliance with the Government's Mexicanization program, ASARCO Inc. divested itself of 51% of its equity in Compania Miners Asarco, S.A. on June 30, 1965. Subsequently, ownership in the divested share was apportioned as follows: 15% ownership in Compania Miners Asarco, S.A. to a group of private investors, and 36% in trust for subsequent public sale. The company's name was changed to Asarco Mexicana, S.A. in 1965. Mexican ownership in Asarco Mexicans, S.A. was increased to 51% in 1967, following the purchase of the 36% share ownership held in trust, and then to 66% in 1974 when ASARCO Inc. divested itself of an additional 15% of its holdings in Asarco Mexicans, S.A. Following its 1974 divestiture of 15% of Asarco Mexicans, S.A., ASARCO Inc's ownership in Asarco Mexicana, S.A. was reduced to 34%. In 1974, the company changed its name for the second time to Industrial Miners Mexico, S.A. (IMMSA). Fiscal Agreement IMMSA entered into a fiscal agreement with the Mexican government in 1969. The agreement, which was renewed in 1974, provided for 100% of the production and export tax corresponding to the federal government with a minimum of 50% of the amount refunded to be reinvested in fixed assets. Further, the agreement permitted the company to

Jan 1, 1985

By John S. Brown

The northeastern United States embraces that area of the Appalachian Mountains, and adjacent territory, beginning on the south at the Potomac River. It thus extends from the flat-lying Paleozoic terrane of the Appalachian plateau on the west, across the folded Paleozoics of the Great Valley and adjacent ridges (Paleozoic and Precambrian), over the Piedmont and New England metamorphic complex (mixed Paleozoic and igenous rocks), broken by the great Triassic rift remnants, onto the subdued coastal plain of Cretaceous and Tertiary sediments. Although not noted as a metal mining region, the area does contain numerous substantial and several outstanding mines, chiefly of the more prosaic metals, particularly iron, zinc, and copper, as well as many minor occurrences of these and a few additional items. These deposits occur to some extent in every subdivision of the area. The region to date (1966) has produced almost 500,000,000 tons of medium to lowgrade iron ore, especially magnetite, including ilmenitic magnetite; 50,000,000 tons of highgrade zinc ore; and 5,000,000 tons of lowgrade copper. In the past, it has yielded small amounts of chromite and nickel, and at present is a large producer of titanium. Precious metals are conspicuously absent, and so also are the Tertiary or Mesozoic igneous phenomena so commonly associated with mines of the West. Hence, a survey of the extensive mineralization · of this region should be instructive

Jan 1, 1968

By W. Tempelaar Lietz

The Ten Section oil field is located in the San Joaquin Valley in Kern County, California. about 12 miles southwest of Bakersfield in Township 30 South, Ranges 25 and 26 East. The accumulation is in a low relief anticlinal dome and has a productive area of approximately 2,200 acres. Discovered in 1936 as a result of seismic work, it was the first field on the floor of the Valley to obtain production. It had a small primary gas cap, and since its inception has been produced by depletion with controlled withdrawal from the gas cap to minimize blowthrough. STRUCTURE AND STRATIGRAPHY The Ten Section structure is an elongated anticlinal dome with flank dips of only about 7 degrees. A map of the field, now fully developed, and a composite log are shown in Figs. 1 and 2. Contours shown on the map are on the top of the first zone, or Marker XA as indicated on the composite log. As shown, the field has a productive closure of only some 350 feet, and there apparently is no faulting in the reservoir. The productive measures in Ten Section are of Upper Miocene age and are known as the Stevens sand. They contain thin, irregular shale or siltstone streaks which vary considerably in stratigraphic position and thickness and apparently are rather discontinuous. As a result, individual sands and shales cannot be correlated over any appreciable area, which makes it difficult to subdivide the sand body into separate zones which are distinct throughout the field. However, there are two fairly persistent siltstone bodies that at the time of development were considered to divide the productive measures into three - zones. The first, or uppermost zone is productive over the entire field and has an average thickness of 180 feet, of which some 65 per cent is sand. It had a primary. gas cap in the crestal area with an areal extent of 930 acres. The second zone has a productive area somewhat smaller than the first zone, but it did not have any original gas cap. It has an average thickness of about 360 feet, of which 55 per cent is sand. The third zone has a very limited areal extent and a maximum productive thickness of 100 feet, of which 80 per cent is sand. Recently, a deeper oil accumulation, termed the "53" sand, was discovered, but it is not discussed in this analysis. In the first and second zones the water table was at 7,980 feet subsea, while in the third zone it was at 8,080 feet subsea. RESERVOIR CHARACTERISTICS Sand Characteristics The Stevens sand in Ten Section is hard and well consolidated, and numerous wells were cored for core analysis. Core data on four representative wells are shown, plotted beside the electric logs in Figs. 3 to 6. The average porosity is 20 per cent, with porosities ranging from 15 to 30 per cent. It is estimated, from cores taken with oil base muds, that the interstitial water content is about 40 per cent. The average weighted permeability is approximately 140, with measured permeabilities ranging from 10 to 3,000 md. As might be expected with practically no correlation of individual sand

Jan 1, 1949

By W. Tempelaar Lietz

The Ten Section oil field is located in the San Joaquin Valley in Kern County, California. about 12 miles southwest of Bakersfield in Township 30 South, Ranges 25 and 26 East. The accumulation is in a low relief anticlinal dome and has a productive area of approximately 2,200 acres. Discovered in 1936 as a result of seismic work, it was the first field on the floor of the Valley to obtain production. It had a small primary gas cap, and since its inception has been produced by depletion with controlled withdrawal from the gas cap to minimize blowthrough. STRUCTURE AND STRATIGRAPHY The Ten Section structure is an elongated anticlinal dome with flank dips of only about 7 degrees. A map of the field, now fully developed, and a composite log are shown in Figs. 1 and 2. Contours shown on the map are on the top of the first zone, or Marker XA as indicated on the composite log. As shown, the field has a productive closure of only some 350 feet, and there apparently is no faulting in the reservoir. The productive measures in Ten Section are of Upper Miocene age and are known as the Stevens sand. They contain thin, irregular shale or siltstone streaks which vary considerably in stratigraphic position and thickness and apparently are rather discontinuous. As a result, individual sands and shales cannot be correlated over any appreciable area, which makes it difficult to subdivide the sand body into separate zones which are distinct throughout the field. However, there are two fairly persistent siltstone bodies that at the time of development were considered to divide the productive measures into three - zones. The first, or uppermost zone is productive over the entire field and has an average thickness of 180 feet, of which some 65 per cent is sand. It had a primary. gas cap in the crestal area with an areal extent of 930 acres. The second zone has a productive area somewhat smaller than the first zone, but it did not have any original gas cap. It has an average thickness of about 360 feet, of which 55 per cent is sand. The third zone has a very limited areal extent and a maximum productive thickness of 100 feet, of which 80 per cent is sand. Recently, a deeper oil accumulation, termed the "53" sand, was discovered, but it is not discussed in this analysis. In the first and second zones the water table was at 7,980 feet subsea, while in the third zone it was at 8,080 feet subsea. RESERVOIR CHARACTERISTICS Sand Characteristics The Stevens sand in Ten Section is hard and well consolidated, and numerous wells were cored for core analysis. Core data on four representative wells are shown, plotted beside the electric logs in Figs. 3 to 6. The average porosity is 20 per cent, with porosities ranging from 15 to 30 per cent. It is estimated, from cores taken with oil base muds, that the interstitial water content is about 40 per cent. The average weighted permeability is approximately 140, with measured permeabilities ranging from 10 to 3,000 md. As might be expected with practically no correlation of individual sand

Jan 1, 1949

By R. D. West

Miscible displacenzent recovers all oil in the area contacted by the injected .fluid, whereas water or immiscible gas drives usually leave substantial amounts of oil as residual. However, the Door mobility ratios associated with a gas-driven miscible displacement cause the sweep pattern efficiency to be much lower than that obtained with water flooding. One way in which the sweep eficiency in a miscible displacement process can be increased is by decreasing the mobility behind the flooding front. This can be achieved by injecting water along with the gas which drives the miscible slug. This water reduces the relative permeability to gas in this area and thus lowers the total mobility. The main operating conditions for the simultaneous injection -vrocess are that a zone of gas exists between the miscible slug and the leading edge of the water and that a su,@cient amount of gas be injected with the water to form the pas volume which is being left in the water zone. Laboratory model studies have shown that the ultimate sweep pattern efficiency can be as high as 90 per cent for a five-spot flooding system. If gar alone is used as the driving medium an ultimate sweep-out efficiency of about 60 per cent would be obtained in the same system. I INTRODUCTION The miscible displacement processes are a step towards total oil recovery. Conventional gas or water drives usually leave 25 to 5.0 per cent of the oil as residual in the swept portion of the reservoir. This residual can be eliminated if the oil is driven by a fluid with which it is miscible. At some reservoir conditions natural gas will become miscible with the oil. This is the "high pressure gas process".' More often, the oil does not contain enough light hydrocarbons to cause the gas to become miscible with the oil at reasonable pressures. In these cases a small band of fluid which is miscible both with the oil and gas must be kept between them2. Less than 2 per cent of the reservoir volume of the slug material is needed to keep the displacement miscible. Both processes work in the same manner, recovering all of the oil in the portion of the reservoir contacted by the injected fluids. The only difference is the manner in which the miscibility between the oil and the injected gas is obtained. Previous publications have contained detailed descriptions of these processes.1,2,3,4 However, total displacement of the oil in the swept region does not guarantee an efficient recovery process. The amount of oil to be recovered is also determined by the fraction of the reservoir contacted by the flood. This fraction is largely determined by the mobilities of the fluids. (The fluid mobility is the permeability of the rock to that fluid divided by the fluid's viscosity, k/p). This. dependence of the fraction swept on the mobility ratio has been shown in previous studies. Fig. 1 shows the ultimate fraction swept in a five-spot system as a function of the mobility ratio. The small drawings show the location of the areas left unswept for two different mobility ratios. The ultimate fraction of the reservoir swept is here considered to be attained when the producing stream contains less than 5 per cent oil at reservoir conditions. THE GAS-DRIVEN MISCIBLE DISPLACEMENT Since there is no oil left in the swept region after miscible displacement the mobility in this region is very high. It is often 50 times the mobility in the unswept regions. This means that the fraction of the reservoir contacted by the injected fluid will be less for a gas-driven miscible displacement than for a conventional water or gas drive. For a five-spot injection system, water would contact the entire reservoir volume, and the low pressure gas would contact about 90 per cent of this volume, while a gas-driven miscible displacement would only contact about 65 per cent of the reservoir. This poor sweep efficiency often offsets the benefits obtained through miscible displacement. Fig. 2 shows what the recovery curves for the three processes might look like for a five-spot system. The curves show the fraction of the in-place oil recovered as a function of reser-

By G. S. Rice, J. A. Davis

The Péchelbronn oil field is located in the province of Alsace, in the Rhine Valley, about 30 miles north of Strasbourg. It is approximately 4 miles wide and 12 miles long, extending from the villages of Lobsann on the north to Wintershausen and Ohlungen near Haguenau on the south. (See Fig. 1.) The productive area includes about 44,000 hectares (107,680 acres). The name Péchelbronn signifies "pitch-spring" or "pitch-fountain." The first exploratory galleries were driven in from the hillside in 1735; and in 1745 the first official concession was granted by the French government and the first pit sunk to a depth of about 30 ft. Extraction by drilled wells was begun in 1879, supplementing the mining operations, and during the next 10 years 200 wells were drilled to an average depth of 172 m. (568 ft.). The bringing in of two "gusher" wells, in 1882 and 1888, respectively, was followed by the abandonment of all underground work. Underground mining, with a view to increasing the production of petroleum by recovering the oil left in the sands after drilling wells, was resumed in 1916. This mining operation started by sinking shaft No. 1 to a depth of 150 m. (495 ft.). The underground developments were pushed during 1917 and 1918 and the annual production of the Péchel-bronn field was increased to about 50,000 metric tons or 350,000 bbl. On the signing of the Versailles Treaty the province of Alsace, which had been taken by Germany as the result of the war of 1870, was returned to France, and the proprietary rights were taken over by the French Government. Concessions or leases, which embraced all the known oil-bearing territory of the field, were granted to the present operating company, Mines de Péchelbronn. This company followed both the drilling and the mining methods of the previous company.

Jan 1, 1927

By K. P. Stricker, H. Keddeinis, K. Grebe

Recent investigations by Mannesmann Research have shown that disintegration of sinter with widely varying quality levels is subject to a much more complex set of influences than was previously assumed. It was confirmed that disintegration at temperatures between 300° and 600°C (570°and 1,110°F) is triggered by the degradation of hematite. The specific tendency of hematite to disintegrate is, however, not constant: sinters containing the same amount of hematite can show widely differing disintegration tendencies, depending on structural homogeneity, porosity, and gangue quantity. Sinters with heterogeneous structures transmit stress to the hematite phase and this favors disintegration. Another factor is the brittleness of the glassy silicate phase, which can be influenced even by small modifications of minor gangue constituents.

Jan 1, 1984

By P. A. Vukmanic, M. Gensamer

Only recently has it been realized that preferred orientations are common in hot-rolled steels. In a recent paper, N. P. Gossl stated that hot-rolled mild steel exhibits a texture different from that characteristic of cold-rolled steel. No complete study of these hot-rolling textures has been reported using the pole-figure method of Wever. The material used in the work reported in this paper was the same material used by Gensamer and Mehl2 in a recent study of preferred orientations in cold-rolled steel, to which reference may be made for the composition and thermal history of the steel. Automobile-body sheet bar 1/4 in. thick was hot-rolled at two temperatures, 780' and 910' C. (1436' and 1669' F.). These temperatures refer to the temperature of the furnace in which the steel was heated; after each pass the steel was returned to the furnace and held there long enough to return to temperature. Although no accurate method was used to measure the temperature after each pass, it was estimated by color that only a slight drop in temperature occurred. In order to determine the effect of any preferred orientation that might have persisted through the normalizing treatment, one specimen at each temperature was rolled in the same direction as the original working direction and the other at right angles to it. The total reduction in each case was 85 per cent, the specimens having been reduced from 0.250 to 0.0375 in. in five passes. Final cooling was in air. Pinhole reflection photograms were taken of all four specimens, with the rolling direction vertical and the X-ray beam at an angle of 7' with the transverse direction (the transverse direction is defined as that direction in the rolling plane perpendicular to the rolling direction). These photograms, taken with a Mo target at 35 kv., are reproduced in Figs. 1, 2, 3 and 4. They show that a more pronounced texture was developed by the low-temperature rolling (780' C.), and that of the two

Jan 1, 1937

By E. P. Polushkin, Henry L. Shuldener

THIS paper describes the results of microscopic examination of a series of brass pipes removed from apartment and office buildings in New York City, adjacent localities on Long Island, and Philadelphia. They were selected as typical of approximately four hundred pipe specimens obtained over a period of five years during an investigation of corrosion in hot-water installations. A part of the investigation is reported in this paper and includes a brief history of the pipes, a description of their inside surface and microstructure, and a study of the effects of corrosion, with particular reference to the structural aspects of local and selective dezincification. Although the bibliography on the corrosion of brass pipes is quite extensive, it refers almost entirely to corrosion in sea water. The authors believe that their examination of this series of pipes, which had been subjected to the corrosive action of fresh water for various lengths of time, may throw some additional light on the problem of corrosion. PIPES EXAMINED The pipes were made by different manufacturers and their sizes range from ¾ in. to 4 in. nominal inside diameter, the majority being within I to 2 in. They can be divided into two groups according to chemical composition: (I) with a copper content of 60 to 62 per cent and (2) with a copper content of 65 to 68 per cent. The first group (pipes made of Muntz metal) comprises 22 pipes and the second (pipes made of high brass) comprises 18 pipes. The pipes had been in service in various locations in the hot-water systems of the buildings involved. Some were taken from horizontal lines in the basement, some from overhead distributors and some from vertical risers. The distance, in terms of feet of pipe, of the specimens from the hot-water generator was no less than 75 ft. and often 100 to 300 ft. In the majority of cases the water-heating equipment was provided with a regulator to limit the temperature of the hot water supply. The normal range of temperature in pipe systems of this kind is 100° to 160°F. WATER SUPPLIES The average chemical composition of the water supplies carried by the pipes is shown in Table I. In evaluating the corrosiveness of a natural water, four factors are considered of prime importance: namely, hardness, alkalinity, pH and silica content. The waters listed in Table I are characterized by relatively low hardness, low alkalinity, low pH and low silica content. The waters of lower pH and higher CO2 content are more corrosive. A characteristic of all of these waters is that they do not deposit a protective mineral coating as do waters with high bicarbonate of lime content, which would be reflected

Jan 1, 1944

By Leslie C. Richards

The competitive position of producers of industrial minerals depends upon the delivered price of their product. Freight charges are a major factor in the sales to consumers. A comparison of freight rates on movements of limestone and silica rock in the Pacific Northwest shows a wide variance in mills per ton mile for like hauls, thereby favoring some localities over others.

Jan 1, 1950

By E. Bicknese, R. Clark

The mechanism and rate of reduction of FeO at conditions similar to those in the stack of a blast furnace have been determined for temperatures from 980" to 1165°C. Preliminary studies of the reduction of Fe2O3 with activated coconut charcoal in a static system (no flow of reducing gas) have shown that the CO2-CO ratio of the product gas depends upon the relative reactivities of the Fe2O3 and charcoal. In a systern with a "hot blast" of CO and Nz (simitar to dry bosh gas), synthetic FeO, and actiuated coconut charcoal, the rate of reduction was not sensitive to the flow of reducing gas, and the rate-controlling step alas the chemical reaction at the metal-oxide interface. Wherz solid carbon was not present, a critical flow rate of reducing- gas had to be met in order to prevent a lowering of the reduction rate. The effect of a less-reactive carbon (blast-jurnace coke) and of a "natural" FeO on the mechanistn and rate, and the mininum amount of carbon necessary in the charge to tnaintain the reducing potential of the gas phase, have been determined. THE importance of iron oxide reduction processes has encouraged many studies of the process reaction kinetics. Despite this, the mechanism is not well-understood and three main theories have evolved, which can be stated as follows: A) the rate-controlling step is diffusion, either gaseous diffusion of the reductant or product gas through a porous solid,' or solid-state diffusion of iron and oxygen atoms through the so1id.2 B) The slow step is diffusion of reducing gas through a stagnant boundary layer. C) The reaction rate is controlled by the chemical reaction occurring at the metal-oxide interface and is proportional to the area of this interface.3 By increasing the velocity of the reducing gas to a flow rate beyond which no increase in the reduction rate is observed, critical flow rate, it may be possible to eliminate B as the slow step. However, as warnere points out, the establishment of a critical flow rate may only assure that the reaction is not limited by a reduction in the reducing potential of the gas and that B may still be the rate-determining step. Edstrom and Bitsianes and Seth and Ross8 show that A and C may both be correct for the reduction of the same oxide, depending upon the stage of the reduction, and that the relative importance of the two mechanisms varies with the porosity of the oxide. Themelis9 has derived expressions which express A, B, and C in terms of the fraction reduction, Rx, of a spherical particle. Thus, in the case of A a plot of In (1 - Rx) vs time must be linear and the time to reach a given reduction is proportional to the square of the particle diameter. For B a plot of (1 - Rx) vs must be linear and the time to reach a given reduction is proportional to the square of the diameter. For C a plot of 1 - (1 - RX)1/3 vs f must be linear and the time to reach a given degree of reduction should be proportional to the diameter. In the case of mixad controlled reactions, none of the plots are linear over their entire length. The results of previous studies, in which the rates of gaseous reduction of iron oxide were measured in the absence of carbon, may not correspond to blastfurnace practice because they ignore the effects of the Boudouard reaction. CO2 +C — 2CO The presence of carbon may alter the mechanism or the rate of iron oxide reduction through an enrichment of the gas phase by Eq. [1]. In this case, the presence of and reactivity of carbon become important. If the Boudouard reaction has no effect on the rate of reduction, the reducing gas could be supplied by some means other than the gasification of carbon at the tuyeres and carbon could, theoretically, be eliminated from the burden. Preliminary studies of the reduction of Fe2O3 with activated coconut charcoal were made to determine if the reactivity (surface area) of the Fe2O3 had any effect on the product gas composition. Two size fractions of Fe2O3 were reduced with charcoal in a static system (no flow of reducing gas). In each case the charcoal was -100 + 325 mesh and was 25 pct of the total charge. One fraction of the reagent-grade Fe2O3 was submicron in diameter. The other fraction was -100 + 200 mesh and was prepared from the former by compacting, sintering at 1300°C, crushing, and screening. In each experiment, the reaction vessel was filled with a mixture of CO and CO, which would be in equilibrium with FeO and iron at the reaction temperature. A furnace was heated to the desired temperature, the vessel was placed in the furnace, and the gaseous products of the reaction were collected and analyzed. The results of these experiments, Fig. 1, show that the gas phase associated with the submicron oxide is more oxidizing than that with the -100 + 200 mesh oxide. Therefore, in a static system, the relative rates of the reduction reaction and the gasification of carbon depend upon the reactivities of the Fe2O3 and charcoal. The reduction of FeO to iron is the most important reaction occurring in the blast furnace and is probably the slowest of the several reduction steps. The mechanism and rate of reduction of FeO in a system containing carbon and a flow of dry bosh gas have been studied. TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AlME

Jan 1, 1967