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By Lawrence B. Wright

The Republic district, Washington, is of new interest because of the discovery of new gold-silver ore within a unique structural pattern. The camp was revived in 1937 fol1owing installation of a plant to treat low-grade disseminated ore at Knob Hill and further stimulation followed discovery of "cross vein" breccia ores in 1939. Previous writers 1-2 ascribed the quartz veins to a latite porphyry stock, but are in disagreement as to its precise location and extent. This study leads to the conclusion that the ores have a more profound parentage linked to a broad system of thrust faults and folds, the mechanical origin of which is related to a southward trending (Sanpoil) syncline connecting with the Lewis and Clark zone of shift described by Billingsley and Locke3 in 1939. The Republic anticliue and a cross anticline recumbent against Cretaceous granodiorite. and involving some 4000 ft of Eocene andesite flows and early Miocene lake beds, localize the ores, mainly along the east flank, in a series of openings simulating drag folds and steeper than the folded flows. These broad structural features no doubt reach deeply into the basement rocks, where at appropriate crossings and junctions it is suggested that heat effects gave rise to ore-making materials, including, in this instance, intrusive breccias that later were mineralized, and comprising the broader bodies of new ores. The breccia ore is seen crosscutting the earlier narrow quartz veins with a welding of the two at junction areas by a second surge of ore minerals. The ore mined and developed since 1937 equals district production from 1896 to 1937 The ores are typified by cherty quartz, adularia and some barite, with fine pyrite and marcasite, polybasite, pyrargyrite, tetrahedrite and gold. Selenium is present, possibly with gold, as a normal selenide. The disseminated ores, as well as the vein and breccia ores, are localized principally in one 500-ft flow (Knob Hill andesite), which has been traced around the crest of the low northward-plunging Republic anticline. The gold-silver ratio in the earlier narrow veins is about I to 4 and in the disseminated and breccia ores, I to 7. The latter higher silver ratio is deemed to reflect the character of the second surge of mineralization. Sills and dikes of the Columbia River (Miocene) basalt cut the folded structure and ore, thus placing the mineralization in the middle Miocene. Introduction The Republic district of north central Washington is of new interest because of the discovery, development and extraction of new gold-silver ore; also, because of a unique local structural pattern believed to be integral with the broader tectonic mechanism of the continental framework. This district had 40 years of modest rating following its discovery in 1896. Its narrow ore bodies, complex mineralogy. and early inadequate metallurgy, together with the apparent bottoming of ore near 1000 ft, limited production to 300,000 oz of gold and 1,000,000 oz silver between 1897 and 1914. The camp was then reduced to lease Life until 1937, when the gold price increase of 1933 to $35 per ounce

Jan 1, 1949

By K. D. Hester, A. W. Fletcher

A nickel-copper sulphide concentrate was treated in a pilot plant at Warren Spring Laboratory during 1961, by a hydrometallurgical roast-leach-solvent extraction process devised to cleanly separate the metal values and produce acid sulphate liquors containing the metals. It is shown that 86 pct of the nickel and 95 pct of the copper could be leached from the calcine, after a sulphatizing roast on finely ground flotation concentrate. Iron was removed from the leach liquor by limestone neutralization with a small loss of values. Copper and nickel were separated by solvent extraction with naphthenic acid in kerosene after partial neutralization of the iron-free liquors with ammonium hydroxide. Hydrogen sulphide and chlorine were used to remove zinc (and residual copper) and cobalt impurities respectively. The recovery of pure copper and pure nickel, by electrowinning, from the acidic solvent extract strip liquors finally produced, appears technically feasible. An economic analysis of production costs shows that small, geographically isolated, nickel-copper sulphide deposits cannot usually be worked profitably by established processes. The requirements for profitable operation on a comparatively small scale could possibly be met by a flotation-roast-leach process. Two difficulties, obtaining satisfactory extraction of nickel from a sulphide concentrate and separating the copper and nickel in solution, have prevented the previous use of this method. A solution to the first problem, dissolution of the nickel, was described in a recent paper by Thornhill.1 It was shown in this paper that copper and nickel in a flotation concentrate could be oxidized to water soluble sulphates by roasting in a fluidized bed with added salt cake. Workers at the Warren Spring Laboratory have shown that the separation of copper and nickel can be accomplished by solvent extraction using a relatively inexpensive carboxylic acid, naphthenic acid. Moreover, the mineral acid required to strip values from the loaded solvent could be produced, and the metals recovered, by electrowinning; thus the latter section of the process was regenerative. The removal of iron from the leach liquor and the elimination of impurities such as zinc and cobalt before nickel electrowinning would be necessary to complete the flowsheet. The process under investigation could therefore be summarized (Fig. 1) as follows: 1) Flotation to produce a bulk sulphide concentrate. 2) Fluidized bed roasting to sulphate the nickel and copper minerals. 3) Leaching of roaster calcine to extract soluble nickel and copper. 4) Precipitation of iron from the separated leach liquor by air oxidation after the adjustment of pH and temperature. 5) Recovery of copper from the iron-free Liquor by pH adjustment and liquid-liquid extraction. 6) Purification of the copper raffinate by removing zinc and residual copper as insoluble sulphides and cobalt as cobaltic hydroxide. 7) Recovery of nickel from the purified liquor by pH adjustment and liquid-liquid extraction. Laboratory and pilot plant studies detailed below, were carried out at the Warren Spring Laboratory, to test the feasibility of each one of the unit processes and to obtain preliminary plant design data. FLOTATION The ore was an altered basic rock containing concentrations of magmatic sulphides.

Jan 1, 1964

By L. R. Duncan, O. M. Wicken

Magnesium, the eighth most abundant element in the earth's crust, is found widely distributed in a variety of minerals. Among the more commercially important ones are magnesite (MgCO,), brucite (Mg[OH],) , dolomite (CaMg[CO,],), and the salts magnesium sulfate and chloride often found in natural brines. Among other commercially important magnesium-containing minerals are olivine ([MgFe],- SiO,) , talc (H,Mg,[SiO,],) , and serpentine (H,Mg,Si,O,) . These are valuable because of desirable characteristics given them by the magnesium content and its placement in the particular crystal structure. These minerals are the raw materials for a host of products including magnesium metal and several grades of magnesia or magnesia- containing materials for refractories, fluxes, fillers, insulation, cements, decolorants, fertilizers, and chemicals. Considering only those minerals valued for their magnesia or magnesium content, over 85% of the material tonnages are processed to be used as refractories. Dolomite, which is used in enormous tonnages for its physical properties in construction, has an important use as a refractory raw material in its own right and, after calcination, as a precipitant for magnesium hydroxide, which is an intermediate for the production of magnesia or magnesium metal. Magnesia from the reaction of calcined dolomite (or limestone) with sea-water or magnesium-containing brines has supplanted much of the production of magnesia from mined magnesite, particularly in the United States. The best known of the minerals directly and widely exploited for magnesia content is magnesite, one of the calcite group of rhombo- hedral carbonates which includes calcite (Ca- CO,) , siderite (FeCO,) , and rhodocrosite (MnCO,) among others. The members of this group enter into a wide range of substitutional solid solutions when the positive ions have similar radii. The radii of magnesium and iron ions are within 6% of each other; hence, magnesite and siderite form a complete series of which breunnerite (ferroan magnesite) is a well-known end member. However, the radius of calcium ion is 36% larger than that of magnesium ion, and only limited substitution exists at each end of the MgC0,-Cam, series. Dolomite is not a member of the calcite group, but results when calcium and magnesium ions alternate in equal number in an ordered structure among carbonate ions. The result of these relationships is that calcite and dolomite, often found intermixed with magnesite, occur commonly as identifiable crystal entities which can often be separated to a varying degree from the magnesite by various beneficiation techniques. Magnesite, when pure, contains 47.8% MgO and 52.2% CO,. The pure mineral is sometimes, but rarely, found as transparent crystals resembling calcite, but, preponderantly, magnesite contains variable amounts of the carbonates, oxides, and silicates of iron, calcium, manganese, and aluminum. Magnesite may be either crystalline or "amorphous" (cryptocrystalline). The crystalline form has a hardness of 3.5 to 4.0. The color may range from white to black with shades of yellqw, blue, red, or gray. The color is not a fundamentally significant indicator of purity, but in a given deposit, an experienced person can often roughly grade magnesite by assessing color and crystallinity. The crystalline form of magnesite occurs in

Jan 1, 1975

By John B. Campbell, George G. Binder, Loren H. Jenks

Conventional methods of producing crude oil generally leave in the depleted reservoir 1 to 3 bbl of oil for every barrel brought to the surface. This paper describes a field test which explores the possibility of using gas-driven liquid propane to improve oil recovery efficiency. Laboratory theoretical and experimental studies leading to the field test indicated that low residual oil values could be obtained using limited amounts of propane driven by gas. The field test involved (I) repressuring the reservoir to the vapor pressure of liquid propane, (2) injecting the liquid propane, and (3) injecting dry natural gas to drive the propane and oil to the producing wells. Considerable preliminary work, including new drilling, work-overs, and a pressure survey was necessary. During the test, oil production rates have averaged about nine times the final primary rates. The field average GOR is still below the pre-test value. Oil recovery to date is 112,000 STB. About one-third of the 143,-000 bbl of propane injected has been produced to date. Results of the C-2 block test are encouraging and larger, more definitive field projects ore indicated. INTRODUCTION The cost of finding new crude oil reservoirs continues to increase. Today the oil industry is drilling more and deeper wells and making fewer big discoveries. Nevertheless, the demand for oil and oil products increases each year. It is natural that oil companies, faced with this situation, concentrate on recovering more of the oil existing in our known crude oil reservoirs. There is room for much improvement. For every barrel of oil brought to the surface by present day methods of producing crude oil, generally 1 to 3 bbl are left behind in the depleted reservoirs. The "unrecoverable" oil in petroleum reservoirs is largely "trapped" by capillarity. Since flushing with a solvent is exceedingly effective in combatting oil loss due to capillarity, much effort in this direction has been made in recent years1,2,3,4,5. Liquefied petroleum gas (LPG) has been suggested as a relatively inexpensive. abundant, easily recoverable solvent for crude. Some operators have observed striking responses in oil recovery at production wells offsetting input wells in LPG storage reservoirs6,7,8. In spite of the low unit cost of LPG, however, it is uneconomic in general to inject a volume of LPG into a reservoir to remove a like volume of oil. A modification of solvent flushing in which a limited quantity of liquid propane is gas driven through a reservoir appears capable of recovering much more than 1 bbl of oil per barrel of propane injected. Also, most of the propane injected should be recoverable for sale or re-use. Since such a process could well have widespread and profitable application, The Carter Oil Co. is making an extensive evaluation of the technique's possibilities. Laboratory development of the gas-driven propane recovery technique was sufficiently encouraging to justify testing in the field. Since 1952, the Production and Research Departments of The Carter Oil Co. have cooperated in a field test in the C-2 Block leases of the

Jan 1, 1958

By A. F. Meger

Coal treatment by oil spraying receives special attention at the Georgetown plant for the dividends it pays in satisfying present customers and attracting new markets. Customer satisfaction requires care, quality control, and use of suitable oils. REPRESENTED here are the ideas and varied experiences of many people in the Hanna Coal CO. who have helped develop, over a number of years, an efficient and flexible method for spraying controlled amounts of oil on coal. Since the Georgetown preparation plant began operations early in 1951, oil treatment of coal has received special attention. It is believed that oil treating will satisfy present customers and also attract new markets. The first step in developing the new method of oil spraying was the construction of a dust cabinet for testing 50-lb samples of treated coal with the available oil sprays on the market. Tests results were tabulated for both indoor and outdoor storage. The graph, Fig. 1, shows results of the original tests made with a 700-sec residual blend and a 500-sec lubricating oil on Georgetown stoker coal of 1¼x3/8-in. size.* The advantages of better price, improperly blended can raise havoc. Some.,pale oils also, although odorless when delivered, give off a sweet sickening odor when atomized under pressure. It is recommended that all products be tested before they are used. There is a specific place for all spraying oils. For example, at a power plant a severe dust condition exists around the stockpile area and in parts of the plant. The cheapest spraying oil made, regardless of odor, will do an excellent job in this case and will save the company 3 to 5c per gal or more. Domestic trade, on the other hand, must be carefully handled to prevent complaints about odor, and the only way to do this is to stay with the proved products after the odor tests have been made. The preparation plant at Georgetown has facilities to handle either tank car or tank truck deliveries. Steam is available at the unloading point if the weather is severe, and there is an indicator at the unloading point to prevent overflowing the 20,000-gal underground storage tank. Systematic test samples are removed from each delivery and sent to the lubrication engineer to insure quality control. Fig. 3 illustrates the chutes in which smaller sizes of coal are treated. Fig. 4 shows the entire spraying system. Buried in the ground is a 20,000-gal tank with immersion heaters grouped around the feeder line to insure adequate gravity flow to the pump under all conditions of weather. Oil flows to a 500-gal preheating tank where the temperature is kept about 150°F by six 1½-kw immersion heaters thermostatically controlled. Hot oil is fed through a self-cleaning disc-type filter to the hydraulic pump. Valves and piping make it possible to transfer oil from one tank to another or to drain the lines for maintenance purposes. All this equipment is below ground level in a covered pump room,

Jan 1, 1955

By R. J. Wygal

A method is presented by which homogeneous, isotropic, and reproducible aggregates of particles such as glass beads, sand, ground glass, etc., may be prepared simply and quickly by using a "particle distributor". Several applications of the packing method to the construction of model reservoirs are described. The flow characteristics of these packings me given. Some factors which limit the usefulness of unconsolidated packs for simulating reservoir rock are overcome through artificial cementation of the aggregates. INTRODUCTION Many laboratory studies of porous media are based on experiments using test packs of sand, glass beads and other granular materials. More confidence can be had in the results of such studies if the test packs are known to have uniform properties throughout, to be mechanically stable and to be accurately reproducible. This paper presents a method by which such packs of a variety of shapes and sizes may be constructed using a particle distributor. Some factors which limit the usefulness of unconsolidated packs as a means for simulating reservoir rock are described. A method of overcoming these limitations, which involves artificial cementation of the packs, is presented. DEVELOPMENT Particles packed by the tamping or vibrating techniques are usually either non-uniform or mechanically unstable. An invention by Currie and Gregoryl overcomes these difficulties to some extent. The invention is based on the use of a stream of falling particles impinging on and passing through a distributor matrix of several layers of closely spaced spheres. The particles are well dispersed by numerous collisions with the spheres. They become homogeneously distributed at some distance below the distributor matrix and at that position are collected in the sample container. This apparatus, however, was found to be ineffective when small particles were used since small particles accumulate on the top surfaces of the spheres. An improved distributor matrix was made, first in the form of a stack of five sieves, and then in the more adaptable form of spaced layers of wire screen. Fig. 1 shows a longitudinal view through a five-layered distributor of eight-mesh wire screen. This device gives excellent results.* Fine particles pass through the distributor with very little hold up. The fine structure of the wire matrix with its many deflecting surfaces ensures good particle distribution. There are no dead areas immediately below the screen as were sometimes observed to occur below a matrix of spheres. Using such a device, 20-30 mesh sands were packed to a porosity of 32.1 per cent at rates varying from 0.17 to 6 lb/rnin. The lowest porosity achieved by tamping small increments of similar sands into a container was 33 per cent. Motion pictures at 3,000 frarnes/sec of the surface of a growing pack of 2-3/4 mm glass beads have helped to show the mechanism by which packs of low porosity are obtained. The beads, although packed at the rate of 5 lb/min, were observed to hit the pack surface singly, for the most part, and at well spaced points of impact. Part of their energy is transferred to surface beads which are thereby

By Rex E. Cheek, Donald E. Menzie

The fluid mapper, a model relatively new to the petroleum industry, was used to study the effect of various mobility ratios on the areal sweepout efficiency for two typical spacing patterns. The experiments indicated the areal sweepout for the five-spot pattern varied from 51.8 per cent at a mobility ratio of 0.093 to 89.1 per cent for a ratio of 24.4. In the direct line-drive pattern, the areal sweepout varied from 58.7 per cent at a mobility ratio of 0.089 to 92.0 per cent at a ratio of 24.8. The fluid mapper may prove useful to determine quickly the effective areal sweepout for any well spacing. INTRODUCTION The effect of the mobility ratio on the areal sweepout efficiency during primary depletion of a water drive reservoir and during secondary recovery operations has recently become more widely recognized The mobility ratio, M, is defined as: _ kjp (displaced fluid) k/u (displacing fluid) where k = effective permeability u = viscosity When the displacing fluid is miscible with the displaced fluid, the permeabilities are equal and the mobility ratio may be expressed as a ratio of viscosities: u (displacing fluid) u (displaced fluid) The mathematical analysis for calculating the areal sweepout efficiency with mobility ratio other than unity is quite tedious.5,11 An experimental method by using a potentiometric model2 in a step-wise manner and in using an X-ray shadowgraph model3,12 with continuous fluid flow has been published. Several types of models have been used to study oil and gas reservoir performance. These models may be classified as physical, electrolytic, potentiometric, X-ray shadowgraph, and fluid mapper. The X-ray shadowgraph and fluid mapper are models relatively new to petroleum engineering and have not been used extensively for specific applications. The theory of the fluid mapper indicates it may be adapted to a study of areal sweepout efficiencies for various mobility ratios as well as other complex problems in petroleum engineering. The use of the model and results obtained when using displacing and displaced fluids of equal densities but different viscosities are discussed. FLUID MAPPER DEVELOPMENT H. S. Hele-ShawV eveloped a fluid mapper model based on the hydrodynamic theory. This theory is that in the steady flow of a viscous fluid between horizontal parallel plates spaced a very small distance apart, the effect of viscous shear is of such magnitude in the vertical plane that the motion in the horizontal plane is practically undisbrted streamline flow. Techniques developed by Hele-Shaw were not expanded and no additional developments in fluid mapper models were forthcoming until A. D. Moore, University of Michigan, published a series of papers starting in 1949, which describe the construction of a flexible and inexpensive model'h nd the fluid mapper technique for the solution of certain problems.' The essential components of the fluid mapper as developed by Moore are::.ln 1. A base slab. made of dental stone (calcium sulphate and water). which is shaped to represent the prototype. 2. Plate glass slightly larger than the slab and spaced

Jan 1, 1956

By E. P. Abrahamson

The effect of transition element binary solid solution additions upon the re crystallization temperature of nickel has been investigated. All additions raised the re crystallization temperature. Both the rate of change of re crystallization temperature with at. pet solute and the limit of initial linearity are found to correlate with the free atom ground state outer electron configuration of the solute element. A comparison of all of the correlations for the transition elements studied has yielded a set of empirical relations, which allows the prediction of the effect of dilute binary transition elements on the recrystallization temperature of other transition elements. The work of Abrahamson, et al.1-7 on dilute binary solution alloys indicated a correlation between the free atom ground state electron configuration of the solute and both the brittle-ductile transition and re-crystallization temperature. Further, it has been shown3,4 that the limit of initial linearity may also be correlated with the solute electron configuration. Since previous studies have dealt with bee and hexagonal base elements, this study is made to note what effect, if any, the fee base structure might have. Nickel also serves to give a solvent configuration which will allow the comparison of all of the transition element solvents. Olsen8 has studied the effect of some trace elements upon the recrystallization of nickel. He included only Ti, Zr, W, Mn, and Co of the transition elements. The differences in change of recrystallization temperature were attributed to the solute atom size and to the solubility of the solute in nickel. PROCEDURE All alloys were made using 99.9 + pet Ni with 0.003 C, 0.015 Fe, 0.007 0, and 0.0007 H. The solute elements were 99.9 + pet pure. According to the published binary phase diagrams9 and metallo-graphic examinations at X750, all solute elements were in solid solution. The alloys were arc melted and remelted four times in the form of cubic 200-g buttons under an argon atmosphere. They were then hot forged at 800oC to 0.750 in. diam, machined to 0.60 in., vacuum annealed for 1 hr at 700°c, swaged to 0.40 in. and annealed at 700oC for 1 hr in vacuum. The grain size was checked and found to be 77 * 20 grains per sq mm. The specimens were then swaged to 0.187 in., yielding 76 ± 1 pet cold work. All alloys were then chemically analyzed for the solute addition. The interstitial contents remained at the values of the starting material when checked on random alloy specimens. The swaged rod was cut into 8.25 in. lengths and heat treated in a gradient furnace for 1 hr. The gradient was maintained at 250" to 850°C over an eight inch length, recorded by twelve thermocouples. Control was ± 3oC, accomplished at the hot end. The recrystallization was determined metallo-graphically over the entire specimen. The criterion chosen was that point on the specimen showing the first recrystallized grain at a constant magnification, X200. Specimens were repeated, and the agreement was found to be generally ± 3oC.

Jan 1, 1962

By Ralph E. Esarey, George V. Cohee

In Indiana, 349 wells were drilled for oil and gas in the year 1942. Of this number, 125 oil wells and 21 gas wells were successfully completed and 203 were dry holes. Drilling activity declined 37 per cent as compared with that of the year 1941. This reduction was brought about largely by Federal Conservation Order M-68, restricting drilling to one well on 40 acres, in order to save steel. This Order was later supplemented to permit closer spacing of wells drilled to sandstone formations in southwestern Indiana. Most of the drilling in 1942 was in the southwestern part of the state. Posey County ranked first, with 94 completions and 44 producers; Gibson County, second, with 77 completions and 38 producing oil wells and 2 gas wells. There were 58 drilling operations in the state at the end of the year. During 1942 a total of 589,734 ft. of hole was drilled, of which 231,702 ft. was wildcat footage. The total initial production of the oil wells completed was 9974 bbl. and of the gas wells, 11,148,000 cu. ft. (Table 2). Of the 349 wells completed, 122 were wildcat wells (Table 3); 26 were completed as oil wells; 17 were extensions to proven fields and 9 discovered new pools. Posey County was foremost in wildcat drilling, with 37 wells completed (Table 6). Thirty-five per cent of the wells drilled in 1942 were wildcat, as compared with 25.5 per cent in 1941. It is anticipated that the percentage of wildcat wells drilled in 1943 will be greater, although the total number ol ,wells drilled in the state will probably be less. The new discoveries in Indiana in I942 were, for the most part, one-well pools in the southwestern part—in Posey, Gibson and Spencer Counties (Table 4). Most of the development in pools took place in the . Hazelton and Kirksville pools in Gibson County, Mr. Vernon pool in Posey County and the Vernon Heights pool in Vander-burgh County. Deeper production was obtained from the Osage limestone in the Hazelton pool at a depth of 2402 ft., 650 ft. below the productive McClosky limestone. The well had an initial production of 140 barrels. Extensions to 17 pools in the southwestern part of the state were successfully completed (Table 5). An interesting development during 1942 was new production from the Devonian limestone in the Dodds Bridge pool, Sullivan County. The Ohio Oil Co. deepened one of its wells, which had been producing from a shallow sand, to the,Devonian, and it was completed for an initial production of 77 bbl. Five other Devonian producing wells were completed in that area. Crude-oil production in Indiana in 1942 was 6,609,000 bbl. (Table I). The Griffin field, Gibson and Posey Counties, which produced approximately 3,550,000 bbl., accounted for more than half of the state's production. The Mt, Vernon and New Harmony fields were next in importance of production, with 684,000 and 523,000 bbl., respectively. The price of crude oil was $1.22 a barrel for the old

Jan 1, 1943

By Edward Martinez

The reactions occurring in the copper segregation process were studied by heating mixtures of chryso-colla, salt, and a reducing agent. The techniques used in this investigation were differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). The initial chloridizing of the oxide copper occurs below 500°C and cupric chloride may be the compound formed. Volatilization and reduction of the copper chloride take place above 550°C, although these reactions do occur to some extent below 550°C. A difference in the distribution of the metallic copper in the reducing agent was found when sodium chloride was used compared to magnesium or calcium chloride. Segregation was obtained with mixtures of cupric oxide, salt, and charcoal with no quartz or silicate present. Preliminary tests indicate that segregation may occur even in the absence of water vapor. The DTA and TGA techniques were found to be of great value in studying these reactions. The copper segregation process is a method for treating oxide copper ores. The ore is heated, most commonly in a kiln, with a reducing agent and a halide salt, generally sodium chloride, to approximately 700°-750°C and held for 30 to 60 min. The addition of the salt results in the migration and reduction of the oxide copper to metallic copper on the surface of the reducing agent rather than in the original mineral structure. The metallic copper can then be recovered by a subsequent leaching or flotation step.1-4 Experimental work in 1923 on oxide copper ores from the Sagasca mines in Chile led to the discovery of the reduction process. It was found that during the reduction of the copper mineral with coal, at about 700°C, the copper migrated to the surface of the coal instead of remaining disseminated in the ore. The unusual behavior of the copper, which caused it to migrate from the ore particles to the coal, was traced to the presence of a small quantity of sodium chloride occurring in the ore. Further experiments with oxide copper ores proved that the presence of a halide, either occurring naturally or admixed with the ore, caused the copper to migrate from the ore particles and to segregate in the charge. The ratio of salt to reducing agent may vary somewhat, but in general 0.5% to 1.5% sodium chloride and 0.5% to 1.0% coal or coke have been mixed with the ore. Less than stoichiometric amounts of salt are required to convert all the oxide copper to a chloride, so that a cycle of reactions appears to be occurring. Several investigations reported in the literature have proposed reactions to explain the mechanism of the process.5-10 There appears to be general agreement that water is necessary for the reactions to occur; that once the sodium chloride reacts with silica or silicates in the ore, the hydrochloric acid formed will convert the cupric oxide in the mineral structure to cuprous chloride. However, there appears to be a conflict of opinion on the reactions involved in the reduction of the cuprous chloride to metallic copper on the surface of the carbon. Rey has indicated that salt, water vapor, and

Jan 1, 1968

By George V. Cohee, Ralph E. Esarey

In Indiana, 349 wells were drilled for oil and gas in the year 1942. Of this number, 125 oil wells and 21 gas wells were successfully completed and 203 were dry holes. Drilling activity declined 37 per cent as compared with that of the year 1941. This reduction was brought about largely by Federal Conservation Order M-68, restricting drilling to one well on 40 acres, in order to save steel. This Order was later supplemented to permit closer spacing of wells drilled to sandstone formations in southwestern Indiana. Most of the drilling in 1942 was in the southwestern part of the state. Posey County ranked first, with 94 completions and 44 producers; Gibson County, second, with 77 completions and 38 producing oil wells and 2 gas wells. There were 58 drilling operations in the state at the end of the year. During 1942 a total of 589,734 ft. of hole was drilled, of which 231,702 ft. was wildcat footage. The total initial production of the oil wells completed was 9974 bbl. and of the gas wells, 11,148,000 cu. ft. (Table 2). Of the 349 wells completed, 122 were wildcat wells (Table 3); 26 were completed as oil wells; 17 were extensions to proven fields and 9 discovered new pools. Posey County was foremost in wildcat drilling, with 37 wells completed (Table 6). Thirty-five per cent of the wells drilled in 1942 were wildcat, as compared with 25.5 per cent in 1941. It is anticipated that the percentage of wildcat wells drilled in 1943 will be greater, although the total number ol ,wells drilled in the state will probably be less. The new discoveries in Indiana in I942 were, for the most part, one-well pools in the southwestern part—in Posey, Gibson and Spencer Counties (Table 4). Most of the development in pools took place in the . Hazelton and Kirksville pools in Gibson County, Mr. Vernon pool in Posey County and the Vernon Heights pool in Vander-burgh County. Deeper production was obtained from the Osage limestone in the Hazelton pool at a depth of 2402 ft., 650 ft. below the productive McClosky limestone. The well had an initial production of 140 barrels. Extensions to 17 pools in the southwestern part of the state were successfully completed (Table 5). An interesting development during 1942 was new production from the Devonian limestone in the Dodds Bridge pool, Sullivan County. The Ohio Oil Co. deepened one of its wells, which had been producing from a shallow sand, to the,Devonian, and it was completed for an initial production of 77 bbl. Five other Devonian producing wells were completed in that area. Crude-oil production in Indiana in 1942 was 6,609,000 bbl. (Table I). The Griffin field, Gibson and Posey Counties, which produced approximately 3,550,000 bbl., accounted for more than half of the state's production. The Mt, Vernon and New Harmony fields were next in importance of production, with 684,000 and 523,000 bbl., respectively. The price of crude oil was $1.22 a barrel for the old

Jan 1, 1943

By Douglas A. Karvonen

INTRODUCTION Although the economy in the Province of Saskatchewan has historically been agriculturally oriented, a major source of wealth has been realized through natural resources such as petroleum and natural gas, coal and uranium and since the 1960's - potash. Potash or potassium chloride, in the form in which it is presently produced in Saskatchewan, is used primarily as fertilizer, a source of potassium, one of three essential elements required for healthy plant growth, with about 5% of production sold to the chemical industry for use in such products as soap and liquid detergent, glass and ceramics, textiles and some pharmaceuticals. Saskatchewan is estimated to have approximately 40% of known world potash reserves and its ten active mines account for some 25% of annual world production. POTASH CORPORATION OF SASKATCHEWAN In an effort to guarantee a fair and lasting economic benefit to the Province of Saskatchewan, the Potash Corporation of Saskatchewan (PCS) was created on February 4, 1975 through an Order-in-Council under the Crown Corporation's Act and later on April 1, 1976, the Potash Corporation Act provided for its continuation. PCS was given the mandate to acquire ownership of a significant portion of the potash mining capacity in Saskatchewan and to establish an organization capable of operating the facilities, marketing the product, and conducting all of the other activities necessary for a successful corporation competing in the world potash industry. The corporation is the largest potash producing and selling organization in the Western World - or third largest in the world. (See also Figure 1). PCS through its wholly-owned subsidiary, PCS Mining, has acquired a whole or partial interest in five geographically distinct producing properties or divisions, representing today more than 40% of Saskatchewan's potash producing capacity. The acquisition of each division was followed by a program designed to exploit and maximize the particular opportunities at each minesite for increased production. To that end, PCS Mining has taken an active lead in expanding to meet future demand and has implemented expansion programs at all properties except for its Esterhazy Division where it has a long-term processing agreement with International Minerals & Chemical Corporation (Canada) Limited. Through its wholly-owned subsidiaries, PCS Mining, PCS Sales and PCS Transport, this provincial crown corporation has the ability to operate as a producer and marketer of Saskatchewan's potash. In certain instances PCS, the parent company, assists in the financing of various projects undertaken by the subsidiaries and in other cases the subsidiary involved arranges its own financing. POTASH RESERVES As a background to the specific issue of financing, it is helpful to describe briefly the nature of the deposit which supports the industry - our collateral, if you like. The potash beds underlying Saskatchewan are sedimentary rock deposits formed by the gradual evaporation of an inland sea during the Middle Devonian period roughly 400 million years ago. Now known as the Prairie Evaporite, this formation stretches from North Dakota and Northeast Montana through Southern Saskatchewan into North-Central Alberta. These beds lie at mining depths ranging from 950 - 1000m (3,000 ft) below the surface, where conventional mining methods can be used, and to 1,650m (5,000 ft), where solution mining must be

Jan 1, 1985

By G. H. Lair, B. J. Langford, S. H. Rockwood

Volumetric reservoir analysis is dependent upon a firm relationship between porosity, connate water, and net pay. Capillary presswe data on core samples interrelate these three factors. It is shown that other reservoir problems may be resolved: (I) whether water production is indigenous or extraneous to the oil producing interval, (2) an oil-water contact is being approached, and (3) whether the oil-water contact is remotely situated. INTRODUCTION Volumetric analysis of carbonate reservoirs challenges the ingenuity of the reservoir engineer due to an absence of data on the minimum oil-bearing and oil-producing pores of a given reservoir rock. Many studies with this as the ultimate objective are available on the physical characteristics and fluid-flow behaviors of the carbonate reservoir. Some of these publications are: Hassler, Brunner and Deahl's1 study of the role of capillarity in oil production; Jan Law's' and A. C. Bulnes3 statistical treatment of core analysis data; Chalkley's method4,5 or estimating specific surface areas and porosity; Walter Rose's9 report on porosity, reserves, and recovery; Archie's78 tex-tural classification of carbonate rocks; Stewart and Spurlock's9 large core analysis; Purcell'sl0 mercury injection method in studying capillary pressure phenomena; Stewart, Craig, and Morse's" model multiple-phase flow test in investigating the relative permeability effect; and Fatt's12 illumi-nating network model of porous me-dia. The present study shows that the static reservoir parameters of porosity, connate water, and net productive thickness may be interrelated by utilizing a statistical arrangement of mercury capillary pressure data in addition to routine core analysis. This report summarizes the techniques that are followed to obtain these relations which are applicable to carbonate and sandstone reservoirs that do not contain clays. Capillary pressure statistical studies may be extended to include clay-bearing rocks by utilizing water capillary pressure data. POROSITY It is necessary that the laboratory determine the porosity value that includes the pores that are filled with hydrocarbons and water in the reservoir. This is the reservoir's total porosity. When true total porosity values are not available, correlations between porosity and capillary pressure characteristics lose their significance since they cannot be related through oil-base mud core data to the porosity and connate water values found in reservoirs. Methods used to obtain reliable porosity data will not be discussed; however, care should be exercised in selecting samples for measurement. In homogeneously porous formations, small core plugs sampled frequently will furnish adequate information. Where heterogeneity, particularly vugginess, is present, large-core porosity data may be required; in such reservoirs a suite of capillary pressure samples may be selected from small plugs. CAPILLARY PRESSURE Capillary pressure data provide a method for relating two carbonate reservoir parameters, porosity and connate water saturation, which in turn permit delineation of productive rock types necessary for selecting the third parameter, productive thickness. Specific applications of capillary pressure data to petroleum reservoirs were suggested by Archie8 and Pur-cell."' Their work demonstrated that in preferentially water-wet rock, porc

Jan 1, 1958

By J.W. Halley

The effects of tin on steel have become increasingly important because of the necessity of using poorly detinned scrap, tin cans, and terne plate, in the open hearth. Since a tin can contains about 1.5 per cent tin, it would be possible to have up to 0.75 per cent tin in steel made with a 50 per cent scrap charge. In order to use tin-containing scrap, it is necessary to know the effect of tin on various grades of steel. The following investigation is by no means comprehensive but covers a number of steels in which tin content is important. Published Work A number of investigations of the effects of tin on rolling quality and physical properties have been published. It has been found that tin increases strength and hardness and reduces ductility and notched impact resistance. The decrease' in ductility and notched impact resistance becomes more marked as the carbon decreases. McKimml found no change in Olsen ductility, Kockwell hardness, yield strength, tensile strength or elongation in cold-reduced strip containing up to 0.124 per cent tin. A tin content of 0.1j per cent gave difficulties in rolling and increased the hardness but 0.21 per cent tin showed no change in properties from material containing very little tin. No explanation of this contradiction is offered. Andrew and Peile2 investigated steels containing 0.10 to 0.25 per cent carbon and up to 0.63 per cent tin. They found an increase in tensile strength of from 100 to 200 lb. per sq. in. for each 0.01 per cent tin on normalized samples. The elongation and reduction of area were decreased and the notched impact resistance was reduced markedly. Quenched and drawn samples did not show embrittling if water-quenched from the draw temperature of 1148°F. (620°C.). They could find no evidence of tin under the microscope. Whitely and Braithwaite3 investigated the effect of tin on rail steel containing 0.55 to 0.60 per cent carbon. They found that 0.08 per cent tin caused a marked decrease in elongation, notched impact resistance and the degree of bend. The tensile strength was increased in some tests and not in others. Bolsover and Barraclough4 investigated the effect of tin up to 0. 50 per cent on a 0.35 per cent carbon steel and on several alloy steels with from 0.30 to 0.40 per cent carbon. They found a comparatively uniform decrease in notched impact resistance with increasing tin on quenched and drawn samples. If the samples were quenched from the drawing temperature or reheated to the drawing temperature and quenched, the embrittling was much less severe. Steels containing molybdenum suffered much less embrittlement than other steels. Experimental WoRk Effect of Tin on Low-carbon Rimmed Steel Increasing quantities of tin were added to four ingots of a heat of the following ladle analysis: carbon, 0.08 per cent; manganese, 0.39; phosphorus, 0.009; sulphur, 0.025.

Jan 1, 1943

By T. D. Murphy

This chapter deals with those types of silica raw materials that have been segregated and refined by natural processes into nearly monomineralic deposits and hence, by virtue of their high degree of purity, have become the sources of commodities having special and somewhat restricted commercial uses. In some instances, these raw materials occur in nature as unconsolidated quartzose sand or gravel and can be exploited and used with very little preparation and expense. More often, they occur as sandstone, conglomerate, quartzite, quartz mica schist, or massive igneous quartz which must be crushed, washed, screened, and sometimes chemically treated before commodities of suitable compositional and textural characteristics can be successfully prepared. The occurrence and distribution of silica raw materials is summarized and an effort has been made to bring commodity definitions, critical properties, and specifications up to date. Presentation of mining and processing methods is considered beyond the scope of this article; they are, for the most part, conventional and well known. New production techniques are currently reported in the trade journals and are later adequately described in technical publications as promptly as competitive restrictions allow. Discussion on Basis of Use ABRASIVE USES Industrial silica used for abrasive purposes falls into three main categories: (a) blasting sand; (b) glass-grinding sand; and (c) stone-sawing and rubbing sand. Blasting sand is a sound closely-sized quartz sand which, when propelled at high velocity by air, water, or controlled centrifugal force, is effective for such uses as cleaning metal castings, removing paint and rust, or renovating stone veneer. It is commonly referred to as Sand Blast sand. Multicycle quartz sand is an efficient blasting agent by merit of its survival characteristics which are soundness, toughness, and hardness. Steel grit and shot have supplanted it to a large extent but owing to their higher cost and tendency toward deterioration in storage, are still not universally used. It is conceded that angularity promotes faster cutting but this is offset by a higher loss in fines. The peening action of a rounded grain is a desirable feature in achieving a satin finish for certain light metal castings but a subangular grain is unsurpassed for fast heavy cutting. Specifications are chiefly based on size frequency distribution but it is mandatory that the grain be free of adhering clay or irony coatings. Material that dusts upon handling will not be tolerated. There is no uniform trade designation for the many blasting sand grades. Most producers sell on the basis of numbered grades; that is, No. 1, No. 2 and so on, this generally connoting fine to coarser grades. Designation of grade by the two sieve sizes between which most of the material lies, is practiced in some areas. Thus, in a No. 1220 grade, 98 pct of the material passes a 12 mesh sieve and is retained on a 20 mesh sieve. Blasting sand specifications vary according to use. Coarse grades range from 4 mesh to 12 mesh, medium grades range from 12 mesh to 30 mesh, finer grades may range from 20 mesh to 100 mesh or finer. Specifications generally call for narrow limits of gradation, requiring precise sizing methods. The fact that most blasting sands are retained

Jan 1, 1960

By J. W. Halley

The effects of tin on steel have become increasingly important because of the necessity of using poorly detinned scrap, tin cans, and terne plate, in the open hearth. Since a tin can contains about 1.5 per cent tin, it would be possible to have up to 0.75 per cent tin in steel made with a 50 per cent scrap charge. In order to use tin-containing scrap, it is necessary to know the effect of tin on various grades of steel. The following investigation is by no means comprehensive but covers a number of steels in which tin content is important. Published Work A number of investigations of the effects of tin on rolling quality and physical properties have been published. It has been found that tin increases strength and hardness and reduces ductility and notched impact resistance. The decrease' in ductility and notched impact resistance becomes more marked as the carbon decreases. McKimml found no change in Olsen ductility, Kockwell hardness, yield strength, tensile strength or elongation in cold-reduced strip containing up to 0.124 per cent tin. A tin content of 0.1j per cent gave difficulties in rolling and increased the hardness but 0.21 per cent tin showed no change in properties from material containing very little tin. No explanation of this contradiction is offered. Andrew and Peile2 investigated steels containing 0.10 to 0.25 per cent carbon and up to 0.63 per cent tin. They found an increase in tensile strength of from 100 to 200 lb. per sq. in. for each 0.01 per cent tin on normalized samples. The elongation and reduction of area were decreased and the notched impact resistance was reduced markedly. Quenched and drawn samples did not show embrittling if water-quenched from the draw temperature of 1148°F. (620°C.). They could find no evidence of tin under the microscope. Whitely and Braithwaite3 investigated the effect of tin on rail steel containing 0.55 to 0.60 per cent carbon. They found that 0.08 per cent tin caused a marked decrease in elongation, notched impact resistance and the degree of bend. The tensile strength was increased in some tests and not in others. Bolsover and Barraclough4 investigated the effect of tin up to 0. 50 per cent on a 0.35 per cent carbon steel and on several alloy steels with from 0.30 to 0.40 per cent carbon. They found a comparatively uniform decrease in notched impact resistance with increasing tin on quenched and drawn samples. If the samples were quenched from the drawing temperature or reheated to the drawing temperature and quenched, the embrittling was much less severe. Steels containing molybdenum suffered much less embrittlement than other steels. Experimental WoRk Effect of Tin on Low-carbon Rimmed Steel Increasing quantities of tin were added to four ingots of a heat of the following ladle analysis: carbon, 0.08 per cent; manganese, 0.39; phosphorus, 0.009; sulphur, 0.025.

Jan 1, 1943

By F. R. Zachar

IT has always been understood, in northern West Virginia where both the Pittsburgh and Sewickley seams are mined, that pillaring or splitting in the lower Pittsburgh seam could break the interval strata and make mining in the overlying Sewickley difficult or impossible. In some instances, however, mining methods practiced in the overlying Sewickley have reversed the problem, resulting in a shifting of the intermediate layer and destroying valuable acreages of the Pittsburgh seam below. The Pittsburgh seam in this area is, on the average, 102 in. thick. About 18 in. of low-quality head coal are left for roof protection as it is mined. Immediately over the coal are two draw slates, two rider 'seams, and a good hard black shale, locally called black rock, which serves as a permanent roof where draw slates and riders are taken down on certain main haulroads. In most areas mined in this seam in the past the bottom has been satisfactory but soft. However, in areas now being mined by the Christopher Coal Co. in Monongalia County the bottom is very hard and unyielding. The Sewickley seam, lying 85 ft above the Pittsburgh, will average nearly 70 in. in thickness and is overlain by massive shales and sandstones. Much of the seam is mined only down to the "sheep skin," a hard band about 4 in. above the bottom, which is composed of relatively hard shale. Fig. 1 shows a typical cross-section through the Pittsburgh and Sewickley seams in the area being discussed. The thin Redstone seam is not deep-mined but is stripped in some locations where it outcrops. Most of the Sewickley seam in the Morgantown areas has been mined out from 10 to 30 years. There are at present only two large mines and five or six others of small production operating in that seam. Mining systems in the past were generally of the room and pillar type with some full pillar extraction. This seam in the Scott's Run area was operated by as many as thirty or forty different companies at one time, during an era beset with strikes, market failures, and depressions. Most of the barrier pillars along the many main haulroads were abandoned, and blocks of Sewickley coal that would be fully recovered with today's machinery were left unmined when conditions became anything less than favorable. Consequently the mined-out Sewickley is spotted throughout with solid blocks varying in size from 100x100 ft to 200x400 ft and larger. It is these unmined Sewickley blocks surrounded by worked-out portions that have caused transmissions of roof stresses to underlying Pittsburgh mining areas, see Fig. 2, resulting in untold difficulty. As the Christopher Coal Co. operates both the Pittsburgh and Sewickley seams, accurate maps of workings in both seams are readily available and are regularly consulted. The first Pittsburgh squeeze attributed to overlying Sewickley blocks occurred in the Arkwright mine, where a shuttle car crew was developing a section consisting of seven panel headings. These entries were being driven in solid coal 3400 ft from the nearest worked-out Pittsburgh area. As mining advanced it was noticed that certain ribs began to slough and certain areas to show signs

Jan 1, 1952

By I. E. Campbell, R. I. Jaffe

Oxygen, nitrogen, and hydrogen are known to be absorbed by titanium at elevated temperatures. Ehrlichl reports that about 30 at. pct oxygen can be dissolved in solid solution by alpha-titanium. Nitrogen also has a solid solubility in alpha-titanium, but there is no information as to its extent. The solid solubility of hydrogen in titanium also is high. Kirshfeld and Sieverts2 report 50 at. pct soluble, while Hägg3 reports about 33 at. pct hydrogen to be soluble in alpha-titanium. General statements are made in the literature that oxygen, nitrogen, and hydrogen embrittle titanium, but no quantitative measurements have been made of the effect of these gases on the mechanical properties of the metal. One reason for this is the lack of a source of titanium pure enough to be considered a suitable starting material. Iodide-refined titanium, made by thermal decomposition of titanium iodide vapor on an incandescent wire,4 contains small amounts of carbon, silicon, iron, and aluminum, but is very low in oxygen, nitrogen, and hydrogen content, and, therefore, was used in this work. A further reason for the lack of quantitative information on the effect of these gases, particularly oxygen, is the difficulty of carrying out accurate analytical determinations at the low concentrations of interest in this work. For this reason, the oxygen, nitrogen, and hydrogen were added in measured amounts as gases, and diffused into the titanium, to avoid the necessity of chemical analysis. The purpose of the work reported here was to isolate and measure the effects of oxygen, nitrogen, and hydrogen on titanium of the highest purity available at the time. The concentrations studied were 0.25, 0.5, and 1 at. pct in each case. Experimental Work One-half of a 24-in. hairpin of iodide-refined titanium was available for this work. The rod was approximately 0.25-in. in diam and had a 0.003-in.tung sten core. From chemical and spectro-graphic analyses, the purity of the sample was estimated to be between 99.80 and 99.95 wt pct. The chief impurities (aside from the tungsten core) were iron (0.04 pct), silicon (0.01-0.1 pct), aluminum (0.05 pct), carbon (0.03 pct). The tungsten core constituted 0.05 pct by weight of the sample. Although some alloying undoubtedly took place between the tungsten and the titanium during the deposition reaction, the core remained substantially intact in the deposited metal. The initial average hardness of the titanium as deposited was 105 Vickers (10-kg load). The maximum hardness was 116 Vickers and the minimum 91 Vickers. The metal was somewhat harder than that currently being obtained by the iodide process, that is, 75-90 Vickers. The rod was cold swaged to ¼-in. diam and then cold rolled in diamond shaped rolls to about 0.080-in. square, using reductions of 15 pct in area per pass. The 0.080-in.-square wire was cut into 6-in. lengths for the preparation of the alloys by the gaseous absorption and diffusion method. ADDITION OF OXYGEN, NITROGEN, AND HYDROGEN TO TITANIUM A modified Sieverts' absorption apparatus, shown in Fig 1, was used in

Jan 1, 1950

By R. E. Carter, F. D. Richardson

Self-diffusion coefficients have been measured for iron in wustite (700° to 1000°C) and for cobalt in cobaltous oxide (800&apos; to 1350°C) by means of radio-isotopes. Both sectioning and decrease of surface-activity methods have been used and a particular shortcoming of the latter method has been disclosed for wustite. The effects of oxygen pressure on the composition of cobaltous oxide and on the diffusion coefficient of cobalt in the oxide have been established. The effect of the preparation conditions of the cobalt-oxide specimens on the diffusion measurements has been determined. It has been concluded that diffusion of cobalt occurs via vacant cation sites and that a cobaltous-oxide disk reaches equilibrium with its environment in a time which is very short compared with that needed for diffusion of the radio-isotope. THE availability of radioactive isotopes in recent years has permitted the measurement of many self-diffusion coefficients which were hitherto impossible to determine. With the advent of radioactivity, the method of measuring diffusion coefficients has also changed. The earlier sectioning method by which the concentration profile of the diffusing species was determined in the diffusion specimen has often been rejected in favor of the decrease of surface-activity method first developed by Von Hevesy,&apos; and extended by Steigman, Shockley, and Nix,&apos; and Raynor, Thomassen, and Rouse." With the experimental arrangement where an infinitely thin deposit of tracer is diffused into a semi-infinite cylinder, the decrease in activity of the active face due to diffusion of the tracer into the specimen is measured by counting the active face before and after diffusion. Under these conditions, the appropriate solution of the diffusion equation is R = e*(l-<K/Z) [1] where R is the ratio of the counting rates after-to-before diffusion, $& is the Gaussian error integral of \/Z, and Z is defined as Z = p2Dt, p being the linear-absorption coefficient of the detected radiation in the diffusion specimen, D the self-diffusion coefficient, and t the diffusion time. In the older sectioning method the concentration distribution of the tracer is found after diffusion by analysing thin parallel sections cut from the active face of the diffusion specimen. As seen from the solution of Fick&apos;s second law for the distribution of an infinitely thin source after diffusion into a semi-infinite cylinder the log of the concentration plotted against x&apos; will be a straight line of slope log e/4 Dt. The diffusion coefficient thus can be calculated directly. The units of the tracer concentration are completely arbitrary, since any change in units does not change the slope of the log c vs x2 lot. Although both of the above methods have been widely used, a thorough experimental comparison does not appear to have been made. Birchenall and Mehl,&apos; during an investigation of the self-diffusion rate of a and r iron by the surface method using Fe" tracer, diffused and sectioned one welded couple. The diffusion coefficient from this run agreed with those by the surface method. Buffington, Bakalar, and Cohen," during an investigation on a and y iron

Jan 1, 1955

By James Terry Duce

In order to facilitate interpretation of the data in this chapter, we print the following excerpts from circulars to authors, compiled by Mr. Frank A. Herald when he was Vice Chairman for Production of the Petroleurn Division: Generally in Table 1 the unit for presentation of data is a field. For our purposes a field is defined as the whole of a surface area wherein productive, locations are continuous. Such unit commonly includes and surrounds nonproductive areas. Such unit commonly includes a great variety of geologic conditions-—several units of continuous productive reservoirs of distinctly different structure and of distinctly different stratigraphy. Therefore it is hoped that our authors will subdivide "field" so as to enable students to make analyses that may have scientific and/or commercial value. As to each space in the tabulation, it is either (1) not applicable, (2) the proper entry is not determinable, (3) the proper entry is determinable, but not determinable from data available to the author, (4) the proper entry is determinable by the author. In spaces not applicable, the author will please draw horizontal lines; in spaces where the proper entries are not determinable, the author will please insert 2; in spaces where the proper entries are determinable but not determinable from data available to the author, the author will please insert y; in spaces where the proper entries are deter-minable by the author he will, of course, make such entries. Generally, y implies a hope that in some future year a definite figure will be available. Inability to determine precisely the correct entry for a particular space should not lead the author to insert merely y. Contributions of great value may be made by the author in many cases where entries are not subject to precise determination. In such cases the author should use his good judgment and make the best entry possible under the circumstances. For many spaces, the correct entries represent the opinion of the author (for example, "Area Proved") and in such cases the entries need not be hedged to such extent as in cases where the quantities are definite yet can be ascertained only approximately by the author. In cases under definite headings but where figures are only approximate, the author may use 2. For example, if the total production of a field is known to be between 1,800,000 and 1,850,000, the author may report 1,8xx,xxx; or if the production is between 1,850,000 and 1,900,000, the author may report 1,9xx,xxx. Where a numeral is immediately to the left of x or y, such numeral represents the nearest known number in that position. As to quantity of gas produced from many fields the question will arise as to whether the figures should include merely the gas marketed or should include also estimates of gas used in operations and gas wasted. Although rough approximations may be involved, our figures should represent as nearly as possible the total quantity of gas removed from the reservoir.

Jan 1, 1936