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By James J. Scott

INTRODUCTION This paper presents the basic principles which must be followed to create a truly inherently safe mining system. The need to relate the support mechanism to be employed to the ground reaction curve and basic rock mechanics principles will be pointed out. The support system must function in concert with the deformations that are inherent in the selected mining system. Following the support selection, the mechanics for installing support must be developed. This is best done through a cooperative effort between mine engineers, mine operators, safety personnel, equipment sup- pliers, and government inspectors both state and federal. Accident statistics, near miss statistics, review of equipment used by others, geologic features, etc. will necessarily have to be studied. The goal of equipment development and selection should be to develop inherent safety by removing the miner from the hazard area or by providing absolute protection for the miner if he must work in close proximity to the potential fall of ground. The role of good productivity in reducing the numbers of men exposed to hazards is emphasized as a good safety measure ROCK MECHANICS PRINCIPLES A thorough understanding of the ground reaction curve surrounding openings to be created is essential in the

Jan 1, 1982

Discussion of the paper of J. V. EMMONS, presented at the Pittsburgh meeting, October, 1914. and printed in Bulletin No. 93, September, 1914, pp. 2233 to 2248. ALBERT SAUVEUR, Cambridge, Mass.-Mr. Emmons is to be congratulated for having placed before us in so forcible and satisfactory a manner a question of much importance-that of the surface decarbonization of steel. Of course, both manufacturers and consumers have known for many years that during the heat treatment of high-carbon steel, surface deca.rbonization is always likely to occur to a greater or less degree, but the subject does not seem to have been investigated with the method and thoroughness it deserves. I am in substantial agreement with Mr. Emmons's conclusions, and I have but little to add to what he has so well said. His statement that carbon dioxide is just as effective an oxidizing agent as pure oxygen is likely to cause surprise and some will wonder whether his investigation has been carried far enough to warrant so unexpected a conclusion. The reaction C + 0 = CO, expressing the oxidation of carbon by pure oxygen, is decidedly exothermic, whereas the reaction C + C02 = 2C0, expressing the oxidation of carbon by carbon dioxide, is endothermic. Decarburization by pure oxygen, therefore, should take place much more readily than by carbon dioxide. One cannot help regretting that the author does not mention' the best way of preventing in a practical manner surface decarbonization while treating tool steel and other high-carbon steels.

Jan 4, 1915

By Henry J. Welge

The approximate methods which are now in use for calculating oil displacement from reservoirs by gas-cycling or gravity-drainage at constant gas pressure, or by water flooding, make use of fundamental relationships derived by Leverett' and Buckley and Leverett.2 The mathematical equations needed are derived by applying Darcy's law to the flowing phases, and by material balance considerations. ln general, any treatment of this type gives. for any particular exploitation time considered, a plot of oil saturation against distance in the reser-voir. The oil recovery must then be obtained by integrating in some manner the area under the plot. A useful analytical method has been derived for computing the average saturation, and hence the oil recovery. Use of this method simplifies the calculations because it makes unnecessary any numerical integrations. and even the saturation distribution plots are not needed. A further advantage of the method is that knowledge of the relative permeabilities is required only for a limited and intermediate saturation range. In both the Buckley and Leverett method and the method discussed here, a linear sand section is assumed, and in the case of gas drive the gas pressure is assumed sufficiently constant both with respect to reservoir position and time so that changes in gas density. solubility, or reservoir volume factor are negligiklle. Thus, the exploitation contemplates oil displacement as by an immiscible phase. Examples are given to illustrate how the new method can be used. INTRODUCTION AND THEORETICAL BACKGROUND This paper treats a simplified method for computing oil recovery when the oil is displaced, from the reservoir sand by a fluid which, within the limits of accuracy desired, can be assumed to be incompressible and immiscible with the oil. The method makes use of two basic relations originally developed for the case of water displacing oil. However, the case of gas displacing oil saturated with gas at a constant (or nearly constant) pressure may also be considered a displacement by an immiscible fluid. This is possible for the reason that the concentration of the gas in the oil never changes if tile pressure is fixed. consequently, any additional free gas must remain undissolved in the oil, and so must act essentially as an immiscible phase. For convenience, the cape of gas drive will be considered first. Both of the two basic relations needed refer to a linear reservoir, or one which may be somewhat idealized so that a constant cross-section is exposed to fluid flow. Further, the displacing phase is injected at one end, or face; of the reservoir, while the produced fluids are understood to emerge at one point only. which is the opposite face of the reservoir. As indicated in Fig. 1, the reservoir may he inclined by some angle 8. The first of the required equations may be derived by applying Darcy's law to both displacing and displaced phases, and subtracting the two equations. The result for water drive has been given previously, as Equation (13) of the reference by

Jan 1, 1952

By K. L. Young

The general energy equation, including change in kinetic energy, was solved by numerical integration and used to evaluate simplifying assumptions and application practices over a wide range of conditions. When extreme conditions were encountered, sizable errors were caused by large integration intervals, application of Simpson's rule and neglecting change in kinetic energy. A maximum error of only 1.31 percent was caused by assuming temperature and compressibility constants at their average value. It was discovered that a discontinuity can develop in the integral for the injection case. This discontinuity indicates a point of zero pressure change and is an inflection point in the pressure traverse. INTRODUCTION When a pressure in a gas well is to be calculated, one of the first decisions is to select a method of calculation. In many instances, this selection becomes a problem because the literature, at best, provides an evaluation of any method for only a limited range of conditions. Once a method has been selected, a question often arises as to the size of the calculation interval which should be used. The question regarding calculation interval arises because an analytic solution is not obtainable and approximate solutions must be used. This paper presents an evaluation of major assumptions and application practices of probably the two most widely used methods for calculating steady-state single-phase gas well pressures. The two methods are Cullender and Smith1-" (numerical integration), and average temperature and com-pressibility. The Cullender-Smith method assumes that change in kinetic energy is negligible and is normally applied in two steps with a Simpson's rule correcton. The average temperature and compressibility method, in addition to neglecting kinetic energy change, asumes that temperature and compressibility are constant at their average values. This method is normally applied for wellhead shut-in pressures of less than 2,000 psi, and in one step. Computer programs were written to compute bottom-hole pressure with and without the assumptions, using various approaches. Values of input parameters investigated are shown in Table 1. Flow rate was limited to a maximum of 5,000 and 10,000 Mcf/D for tubing sizes of 1.610 and 1.995 in. ID, respectively. Flow rate was also limited to 10,000 Mcf/D for a tubing size of 2.441 in. ID when wellhead flowing pressure was 100 psia. These limitations were imposed on flow rate so as not to exceed sonic velocity. The z factor routine available necessitated limiting bottom-hole temperature to 240F and wellhead pressure to 3,000 psia. Pressures were compared on the basis of percent deviation from the trapezoidal integration of Eq. l or 2 at 100-ft intervals. A preliminary investigation indicated that a 1,000-ft interval solution would differ from a 50-ft interval solution by less than 0.25 percent; therefore, the 100-ft interval was chosen for a base. For the purpose of comparison, deviations less than 1 percent were considered insignificant. where 111.1 qeC2/d p = kinetic energy term. Eqs. 1 and 2 can be evaluated numerically at specific depths using the trapezoidal rule as shown by Cullender and Smith. If change in kinetic energy is neglected and temperature and compressibility are assumed constant at their average values, Eq. 1 can be integrated to give the average temperature and compressibility equation,

By F. L. Holderreed

A choosy in what they would smelt. The furnace charge had to be coarse, and it had to be rich. They discarded fines in excess of about 1/10 the total weight. They wanted 10% copper content and fussed about anything with as low as 5%. They concentrated the copper content of the charge as much as they could by prior selection. They roasted off enough sulfur to further enrich the copper content of the succeeding fall of matte (a melt of cuprous and ferrous sulfides or Cu2S.FeS). Then they desulfurized the iron and fluxed it by carefully adding silica (quartz, not silicates) for a slag of lower density than the cuprous sulfide (Cu2S or white metal). After skimming off the slag, they further desulfurized the white metal by blowing the molten bath with compressed air. The result was blister copper. Yesterday Their techniques and furnaces? Some experimented with mechanically rabbled roasters, but their standard roasting practice was burning coarse sulfide ore in 250-ton heaps. These heaps, approximately 24 x 24 x 6 ft, were burned for about 75 days down to 6-10% sulfur. The turnaround time for a given roasting position was 100 days. Assuming the base was a hearth, the calculated rate of treatment was on the order of 0.004 tpd per sq ft.

Jan 1, 1971

By H. C. Fiedler

X HE development of the cube-on edge secondary re-crystallization texture in Si-Fe strip requires that normal grain growth be restrained. It has been shown that the degree of restraint and hence the completeness of secondary recrystallization depends upon the size and number of second-phase particles, which in turn is dependent upon the prior processing history.1y2 The purpose of this note is to show that, for heats in which manganese sulfide particles are providing the restraint to grain growth, the choice of hot rolling temperature depends upon the manganese content. The making and processing of the heats to the final gage of 0.012 in. has been described.3 The compositions are given in Table I. Apparent in Fig. 1 is the decrease in the ability of strips hot-rolled from 1175°C to undergo secondary recrystallization as the manganese content increases. It has been shown that 1175°C is below the solubility temperature of 0.014 pet S in even the 0.038 pct Mn alloy: and the observed behavior is attributed to an increasing fraction of the sulfur forming large manganese sulfide particles at the heating temperature for hot rolling. This fraction of the sulfur is thus unavailable to subsequently form the small, uniformly dispersed particles which are needed to restrain normal grain growth. Since the sulfur is completely in solution at 1325°C,3 strips from all three alloys show strong secondary recrystallization behavior when hot-rolled from that temperature.

Jan 1, 1969

Karl L. Fetters moves to the front of the AIME organization this month as the 1964 President of the Institute. He will take the chair vacated by outgoing President Roger V. Pierce at the Annual Meeting in New York, already well-rehearsed in his forthcoming duties after a year of preparation as AIME President-Elect. Dr. Fetters is highly qualified for his new responsibilities on both the administrative and professional level. For the past five years, he has been vice president for research and development at The Youngstown Sheet and Tube Co. in Ohio, where he has achieved wide recognition as an out- standing metallurgist and executive. A native of Alliance, Ohio, he obtained his early education in the public schools of his home town and displayed a singular precocity when he launched his professional career as a chemist for the Morgan Engineering Co. at the age of 16. His new career, however, was soon set aside in favor of four years of higher education at the Carnegie Institute of Technology, whence he emerged in 1931 with a bachelor's degree in metallurgical engineering. Surprisingly, and perhaps owing to the employment stringencies of the Depression years, the first job his new qualifications earned him was that of stationary engineer at the Cunningham Sanitarium in Cleveland. After two years of ministering to the mechanical ailments of this institution, Dr. Fetters relinquished his post for a more suitable one in the field of metallurgy.

Jan 2, 1964

By J. E. Worthington, W. H. Spence, I. T. Kiff

Gold was discovered at the Haile mine in Lancaster County, South Carolina, in 1827 or 1828, and since that time the mine has been worked intermittently by both open-pit and underground methods until its forced closure in 1942 by World War II. Production figures are incomplete, especially for the early years, but the total gold produced is estimated to have been greater than 200,000 oz. Thus, the Haile mine has been the most productive gold mine in the eastern United States. The upper, residually enriched ores were relatively rich, but the bulk of the production has come from the mining of lower grade ores. General Geology The Haile mine is located in late Precambrian or early Paleozoic rocks of the Carolina slate belt at the edge of the Atlantic Coastal Plain [(Fig. 1)]. The metamorphic grade is lower greenschist facies and the rocks have been folded into a sequence of northeast-trending isoclinal folds. The gold is associated with siliceous, pyritic, and kaolinized felsic pyroclastic and tuffaceous rocks in an interbedded volcanic and volcanoclastic sequence of felsic to mafic tuffaceous rocks and argillaceous sediments [(Fig. 2)]. The ore bodies occur in two northeast trending zones approximately 500 m apart; each zone is 30-70 m wide and 600 m or more in length, with possible extensions to the east beneath the Coastal Plain sediments. Mineralogy. Gold in the Haile mine is always associated with siliceous and/or pyritic ores. The gold occurs in at least three states: As native gold as originally deposited; as residual gold derived from the breakdown of pyrite; and as gold included in pyrite. Major associated minerals in addition to quartz and pyrite are kaolinite, sericite, and iron oxides. Minor molybdenite, arsenopyrite, pyrrhotite, copper sulfides, sphalerite, rutile, and topaz are also present. Petrology. The gold-bearing ore zones vary from highly siliceous rocks to pyritic massive sulfide lenses. This variation is most easily seen today along strike from the Haile pit to the Red Hill pit. Ore grade material still exposed in the wall of the Haile pit consists of a highly siliceous and very thinly bedded rock containing minor pyrite. Along strike, the character of the mineralization changes to pyritic massive sulfide lenses occurring interbedded with siliceous horizons at the Red Hill pit. The siliceous rocks vary from the thinly-bedded material as just described from the Haile pit to silicified fragmental-appearing rocks to totally recrystallized cherty rocks lacking any recognizable primary features. Scattered, apparently at random, throughout the very thinly-bedded and very fine-grained ore face of the Haile pit are seemingly anomalous silica-rich clasts or concretions up to 5 cm in diameter which will be discussed later in this paper. Alteration. One of the most striking features of the Haile deposit is the alteration mineral assemblage which is intimately associated with the siliceous and pyritic ores. This altered material has been intersected in drill core at depths greatly exceeding the modern weathering profile and is, therefore, of hydrothermal origin rather than from supergene processes. This "sericite," actually a fine-grained mixture of sericite, kaolinite, and quartz, can be shown to stratigraphically underlie the gold- quartz-pyrite zone, and is well exposed in the open pit just southeast of the Haile and Bumalo pits. Relict textures indicate that this highly altered material was originally a felsic ash flow. Other similar alteration zones have been found in outcrop and drill core underlying the remaining ore bodies. Thus each of the mineralized zones consists of two parts: A siliceous and/or pyritic gold-bearing ore zone which is stratigraphically underlain by a zone of high alumina minerals, in this case sericite and kaolinite along with variable amounts of quartz. A green chrome mica, presumably fuchsite, is present in trace amounts in the high alumina zone. Genesis An adequate model to explain the origin and distribution of the gold deposits in the Carolina slate belt is presently lacking. Worthington and Kiff1 suggested a volcanogenic origin for certain gold deposits in the North Carolina slate belt from the waning exhalations of felsic volcanic piles. They also pointed out that such an origin has similarities to many epithermal precious metal deposits located in more recent volcanic piles in the western United States. A further key to the understanding of the genesis of the gold mineralization at the Haile mine is the close association of the mineralization in siliceous and sulfidic horizons to the genetically related and stratigraphically underlying high alumina alteration. Such high-alumina alteration is common around felsic volcanic centers in the Carolina slate belt and the mineralogy as seen today consists of some combination of kaolinite, sericite, pyrophyllite, kyanite, andalusite or sillimanite depending on the local prevailing grade of metamorphism. Accompanying the high-alumina alteration are large quantities of pyrite and iron-oxide minerals as well as characteristic minor accessory minerals often including base metal sulfides, fluorine-bearing minerals (topaz, fluorite, apatite), titanium-bearing minerals (ilmenite, rutile),

Jan 1, 1981

By Gerald A. Munson, Fremont F. Clarke

During recent years the use of lithium has expanded greatly in industrial, chemical, and metallurgical fields, while at the same time modernized methods of mining and refining lithium have increased production. Technical literature includes many papers describing the geology and mineralogy of lithium deposits. Mining and beneficiating problems, however, have not been thoroughly described. Published reports have failed to emphasize that one of the chief reasons lithium minerals were not extensively mined until recently is the difficulty of beneficiation. Four lithium minerals of pegmatites and the lithium-sodium-phosphate byproduct from the brines at Searles Lake, Calif., have been sources of lithium. Among the pegmatite minerals, only spodumene and petaline are known to occur in deposits large enough to support large tonnage operations. Spodumene, a lithium-aluminum-silicate, is the principal lithium mineral mined in the U. S.

Nov 1, 1955

By O. E. Kiessling

THE present system of competitive exploitation of oil pools results in losses, both of petroleum and of profits. Under a competitive system the owner produces or withholds his product according to the price, which reflects the demand, but in the pe-troleum industry the producer does not have complete control over the expansion and contraction of his out-put. Under a series of court decisions, reviewed in detail in the paper, petroleum is not covered by- the general theory of English common law that the owner of land owns everything from the center of the earth to the sky within the areal limits of his property, but is considered to be his only when he has reduced it. to possession, which he can only do by taking it out of the ground. If A can obtain possession of the petro-leum which is beneath the property of B without tres-passing on B's property he commits no legal wrong and B has no defense except to get it into his (surface) possession before A takes it. No one would expect an. owner under such a system to forego the possibility of securing some oil from his property in order to in-crease the ultimate production of the pool. The pe-troleum industry. should offer a constructive program, that will eliminate losses and protect the interests of individuals as far as possible. If improved methods of oil recovery can be applied the quantity of petroleum recovered might be double or even treble the amount recovered by ordinary procedure. But increased recovery is not the only benefit from pool development. In brief, the following advantages can be claimed for unit operation: 1. Saving in development and operating costs. 2. Less danger of damage to the fields by defective wells. 3. Development is better gaged to fit market demand and to effect the most efficient recovery of oil. 4. More oil, gas, and gasoline can be marketed. 5. By regulating pressures, recovery .of oil and gas will be greater and the wells will flow longer. Reagan County (Big Lake), Rainbow Bend and Cabin Creek are examples of longer life of pools thus obtained.

Jan 11, 1927

By Herbert F. Miller

For a long time I have believed that the gas- and brick-costs of open-hearth furnaces using prodncer-gas could be greatly decreased by a change in the design of the port, which would materially reduce the first-cost of the furnace, the rebuilding-cost, and the repair-cost. The defects of the present type of such furnaces, which has clone duty for so many years, may be studied in Fig. 1, in which A A are the two air-uptakes, B is the gas-uptake, and C the end of the gas-port. In the present type of furnace, C is practically 011 the edge of the bath and therefore combustion begins to take place at that point, but has no effect until the gas passes from 5 to 10 ft. into the hearth. As the furnace grows older, C moves back by reason of the burning or falling down of the arch. The furnace reaches its highest efficiency when C has moved a certain distance, but is still near enough to the bath for the overhead layer of air to hold the gas down on the bath, and far enough back to permit combustion to take place at some distance from the bath. This latter fact means that the temperature is sufficient to melt steel at the edge of the port. From this time on, the furnace decreases in efficiency. What is the reason ? As C moves further hack, the gas is released from the gas-port at a point where there is little or no overhead layer of air. The result is that the gas floats along the roof, with the air mostly underneath it. Why the air does not stay over the gas is readily seen in Fig. 1. The lines of draft naturally run parallel to the length of the furnace. The air-uptakes being on the sides and the gas-port in the middle, most of the air will naturally be drawn along the sides of the furnace and the layer of air will be thinnest over the gas, where it is most needed.

Jan 1, 1914

By J. P. Smith

Permian salt measures carry extensive lenses of soluble potash salts in north central Germany. Potash deposits of Oligocene age are found in the Upper Rhine Graben of Alsace (France), and in the Catalonian Basin of Spain. These deposits are found in a wide range of structural settings. Reserves are large, and the production of potash salts is an important phase in the economy of each of these countries.

Jan 1, 1950

By H. E. Wilborg, G. V. Henderson

This chapter deals with those sands employed by foundries for the manufacture of cores and molds used in the casting of such common metals as steel, gray iron, ductile iron, aluminum-based alloys, and copper-based alloys. Most metal is cast in "green sand" molds in which the sand mixture, consisting primarily of silica, clay, and water, forms a plastic material. This plastic material is rammed around a pattern in a split box called a flask, then the box is separated, the pattern is withdrawn, and the metal is poured. These green sand molds are broken apart when the metal has solidified. The sand is then remixed and a new mold made for the next casting. To a lesser extent silica sand is mixed with resins or oils and, after forming, the mixture is hardened by either heat or chemical reaction. In any case, the foundry mold or core is used just once before being broken up and remixed for manufacturing another core or mold. By far the greatest consumption in the foundry is of those types of sand high in silica, low in clay (under 0.5%), and occurring in numerous locations thoughout the United States. Consumption End Uses Foundry sands fall into four distinct categories: silica sand, lake sand, bank sand, and natural molding sand. Silica sand is a general term used to describe washed, graded, dried, and cooled clay-free sands which are found in many parts of the United States. They generally contain 90 to 100% silica but vary greatly in chemical analysis and grain structure. Lake sand is the sand dredged from Lake Michigan or dug from the dunes bordering that lake. Bank sand is composed primarily of silica grain but containing up to 5% clay. It is shipped in both the damp and dry state but the normal processing of bank sand consists only of drying and scalping. Occasionally two different grades of bank sand are blended prior to or during loading. Natural molding sand is a term used to describe a sand containing sufficient clay as mined to be suitable for molding purposes. Clay content may vary from 10 to 24% with the balance of the material consisting primarily of silica sand. These sands range in fineness from one peaked on the 20 mesh to one which contains more than 50% of the particles passing the 270 mesh. Lake sands are relatively coarse and are used in great quantities for the production of automotive castings. Bank sands and natural molding sands are gradually phasing out as the production of castings becomes more a science and less an art. The vast majority of foundry sands used today are those known as the silica sands and lake sands. Foundry sands are used in two basic ways. The majority are used in the green or uncured state with the balance used in the cured or set state. Green sand is grain bonded with clay and contains varying amounts of water to plasticize the clay in order to bond the grains together. Green sand is either naturally bonded or "synthetic" sand. The naturally bonded molding sands are generally found in the Hudson River Valley of New York State, Cumberland County in New Jersey, and in Tennessee and Mississippi. Synthetic sand is molding sand compounded in the individual foundry. It is made up primarily of graded silica sand, western or southern bentonite, water, and carbonaceous and/or cellulosic materials. Green sand is used primarily in making molds. The use of naturally bonded green sand has been declining for many years, primarily because naturally bonded sands are more difficult for the foundryman to find and control. Synthetic green sand, on the other hand, can be

Jan 1, 1983

By Philip Henry

THERE is a difference of opinion among engineers on the subject of depreciation in general, and still more on its application to any given case. The committee which was appointed by the American Society of Civil Engineers to make a report on Valuation of Public Utilities, states "There is no subject connected with valuation about which there are more diverse views than those relating to depreciation;" and in the discussion which took place upon the presentation of the preliminary report of this committee in January, 1914, that part of the report dealing with depreciation called forth more discussion than any other. From this discussion it was evident that the word " depreciation" was not always used in the same sense, so it is quite important that some definition be adopted. As this paper relates to the proper method of treating depreciation by corporations or individuals operating oil properties, both of which must make a return of annual net income to the government in connection with the income tax, it will be in order to adopt the definition of the Internal Revenue Bureau. Under date of Mar. 29, 1910, the Commissioner of Internal Revenue of the Treasury Department stated "Deduction on account of depreciation of property must be based on lifetime of property, its cost, value and use." Again, on Form 1035, "Return of Annual Net Income" for miscellaneous corporations (Section 2, Act of Congress approved Oct. 3, 1913), a deduction from gross income is allowed for "Total amount of depreciation for the year." This item is defined more particularly as follows: "The amount claimed under Item No. 5 (b) for depreciation should be such an amount as measures the loss which the corporation actually sustains during the year in the value of buildings, machinery, and such other property as is subject to depreciation on account of wear and tear, exhaustion, or obsolescence. The amount taken credit for on this account in order to be allowable should be so entered on the books as to constitute a liability against the assets of the corporation. The amount claimed under this item should not cover losses in the value of stocks and bonds. Decrease in the book value of securities owned, so far as such decrease represents a decline in the actual value of such securities, should be deducted under item 5 (a) of the return.

Jan 1, 1915

By Henry Louis

The present paper comprises two parts, which have but little con nection with each other. The first is practically a continuation of the investigation on the specific gravity of gold liberated by means of acids from its alloys, on which subject I had the honor of presenting a brief note to the Institute in 1893 (Trans., xxii., 117); the second describes a series of experiments on the behavior of amorphous gold under the action of heat. By the kindness of Prof. W. C. Roberts-Austen, C.B., F.R.S., chemist to the Royal Mint, I have been permitted to conduct these experiments in the mint assay-office, all the splendid resources of which institution were freely placed at my disposal. I desire at the outset to express my obligations to Prof. Roberts-Austen and to all the staff of the mint assay-office for their kind assistance at all stages of my experiments. I.—The Specific Gravity of Gold in Alloys. In the note already referred to, I published my discovery that the gold left on dissolving out the silver from an alloy of gold and silver (which I shall here term " residual amorphous gold ") has a higher specific gravity than ordinary molten gold. I also pointed out that I had worked on very small quantities of material and with balances and weights on the accuracy of which I could not implicitly rely, and that in so far my numerical data were inconclusive, although I had but little doubt of the correctness of the broad fact. The experiments now recorded were made under the most advantageous circumstances and with various refinements. Particularly, I found that the ordinary form of specific-gravity bottle was responsible for several small sources of error; and I accordingly designed an improved form (Journal of the Society of Chemical Industry, April 30,1894, vol. xiii., p. 322), which I used for this work. The

Jan 1, 1895

By R. H. Martinson, E. Teghtsoonian

The effects of magnesium-rich surface layers of varying thickness on the mechanical properties of LiF have been studied. The yield stress, critical tensile stress, and work-hardening slope increase linearly with layer thickness, while the strain to fracture decreases yapidly with increasing layev thickness. The results of tension tests, supplemente!d by metallogvaphic evidence, indicate that the yield stress and the critical tensile stress of LiF are not determined by surface-source operation. DESPITE many studies, which have recently been reviewed,' certain fundamental aspects of the plasticity of LiF remain obscure. For instance, one question still awaiting a satisfactory resolution is: does the nucleation and/or multiplication of dislocations in LiF occur preferentially near the crystal surface? It is now well-known that mobile dislocation half-loops are readily introduced into LiF by surface damage and that the mechanical properties of LiF are affected by such surface damage. However, it is not known whether, in the absence of large numbers of artificially introduced surface sources, dislocations arise more easily near the crystal surface than in the crystal interior. It is also not known to what extent existing mobile dislocations multiply preferentially near the crystal surface. The present work is an experimental study of these matters. A short investigation of the effect of magnesium -alloyed surface layers on the deformation of LiF single crystals has been published by Westwood.~ Some relevant conclusions drawn from this research are restated here for purposes of comparison with the present work. 1) Tests on as-cleaved, chemically polished, coated and uncoated specimens show that a coating can restrict the operation of artificially introduced surface sources, thereby raising the yield stress. A coating also decreases the initial rate of work hardening of as-cleaved LiF crystals by reducing the number of active dislocation sources, so that mutual dislocation interference effects are lessened. 2) A catastrophic breakthrough of groups of edge dislocations piled up against the coating can cause stress drops in the stress-strain curve. 3) A surface coating can act as a stable barrier to the egress of dislocations, causing pile-up,

Jan 1, 1965

By Oren C. Baptist, Carlon S. Land

Laboratory research has been conducted to evaluute the effect of clay hydration on the permeability to gas of water-sensitive reservoir sands. Samples of a .sandstone containing trace amounts of montmorillonite and a sample of montmorillonite were .studied in the laboratory to detertnine whether swelling or dispersion was the cause of permeability reduction in these samples. Heliuin, containing various amounts of water vapor, was used to hydrate the clay minerals and to determine the gas permeability at various stages of clay hydration. The amount of water adsorbed by the samples using this method is small. The nonwetting-phase permeability at higher water saturations war investigated by saturating the with water and measuring the permeability to humid helium while decreasing the water saturation, Relative-permeability curves obtained from results of these procedures were used to estimate the effect of the swelling of trace amounts of mont/tlorillonite on the permeability of the .samples. Most of the damage to the permeability when reservoir sands containing trace amounts of montmorillonite are exposed to fresh water is due to dispersion and movement of clays. Blockage of pores by the increased volume of expanded montmorillonite is believed to result in permeability damage that is small in comparison to the observed damage to the samples tested. INTRODUCTION Studies have shown that permeability is severely damaged when sands containing only small amounts of montmorillonite are contacted by fresh water.15 When samples of sands containing large amounts of montmorillonite are placed in fresh water in the laboratory, these samples may completely disintegrate, forming an unconsolidated mass of larger volume than that occupied by the dry sample." In this case, it is apparent that the swelling of montmoril-lonite has destroyed the pore structure of the sand. If only a trace of montmorillonite is present in a sand. samples may remain intact when saturated with water, although the permeability to water is a small fraction of the gas permeability of the dry sample. Many workers in the field of water sensitivity have attributed this reduction in permeability to the blocking of pores and reduction of pore size by the increased volume occupied by expanded mont- niorillonite. if the sand contains a detectable amount of montmorill'onite or mixed-layer clay containing rnontmorillonite. Logically3 the smaller amount of montmorillonite present in a sand, the smaller should he the effect of montnlorillonite swelling on permeability; however, the quantity of montmorillonite sufficient to cause severe damage by swelling is not known. Although hundreds of samples have been tested in our laboratory, no correlation has been established between the amount of montmorillonite in samples and the permeability reduction caused by fresh water. To many petroleum engineers, the phrase "clay swelling" is synonymous with "water sensitivity", or "permeability reduction" implying that any formation damage due to the hydration of clays is caused by swelling. Although all clays adsorb water on their surfaces, montmorillonite is the only clay mineral commonly found in reservoir rocks which adsorbs water between intercrystalline layers, resulting in expansion of the clay particle. As montmoril-lonite swells, the first few layers of water adsorbed between platelets are strongly held and well oriented, and the montmorillonite retains its crystalline structure, although expanded. As swelling of sodium montmorillonite continues, the platelets become farther apart and the forces orienting the platelets in the crystalline structure become weaker, resulting in a less orderly orientation of platelets. In an abundance of water, small groups of platelets may become detached from the original monl-rnorillonite particle and may be dispersed throughout the water phase. Because of its swelling properties, sodium montmorillonite is very easily dispersed in water. Particles of other clay minerals. such as illite and kaolinite may also be dispersed in water. causing water sensitivity of sands not containing montmorillonite. The presence of an immobile layer of water adsorbed on the surface of clays has been considered a possible cause of the low permeability to water of dirty sands. Grim states that the thickness of the layer of immobile water held by sodium montrnorillonite is three nlolecular layers or 7.5 A (angstroms), with some orientation of water extending to 100 A. Assuming a very thick, immobile water layer adsorbed on the surface of a pore represented by a capillary tube, the maximum effect of the water layer on permeability can be calculated. Using a pore radius of 10 ' cm and an immobile water layer of 50 A. the calculation shows the permeability to be reduced only 2 per cent. Similar calculations can be used to show that the effect of electro-osmotic counterflow is of the same order of magnitude as that of bound water. The reduction of the permeability to water by either an immobile water layer

Jan 1, 1966

By D. R. Parrish, T. M. Geffen, R. A. Morse, G. W. Haynes

Flow tests on small core plugs have indicated that a large amount of gas is trapped and not recovered by water flooding a gas sand. Instead of I to 15 per cent pore space, as is usually assumed, the residual gas saturation is 15 to 50 per cent pore space, and is thus of the same magnitude as residual oil after water flooding oil sands. A thorough investigation was made to ascertain that large amounts of residual gas actually remain in reservoirs after a water flood and that this condition is not merely a laboratory phenomenon. In field experiments, the amount of gas left in a watered-out gas sand was measured by use of a pressure core barrel and the residual gas saturation of two watered-out gas sands was determined by electric log evaluation. In the laboratory, an investigation was made of factors that could possibly cause the value of residual gas saturation as measured on small core plugs to differ from that in the reservoir, and the effect of these factors on the amount of residual gas saturation was studied. The factors studied include flooding rate, static pressure, temperature, sample size and saturation conditions before flooding All evidence established that a relatively high gas saturation is trapped in water flooded gas sands and that this residual gas saturation can be measured in the laboratory by tests on small core plugs. INTRODUCTION There. has been general agreement among engineers that very high recovery of gas could be obtained from natural reservoirs By water displacement. Gas recoveries of 80 to 95 per cent of the original gas in place have become the normal expectation in water drive fields. The assumption of high recovery has been based on: 1. low density and viscosity of gas compared with water; 2. the erroneous assumption that the flow relationship in a gas-liquid system where gas is the displaced phase will be the same as when it is the displacing phase. It has long been recognized that gas can flow at very low gas saturations (in the range of 1 to 15 per cent pore space) in systems where liquid is being displaced by gas. By assuming the reversibility of this process, the conclusion was reached that the residual gas saturation following water flooding of a gas reservoir would be the qame (1 to 15 per cent) as that at which gas first flowed continuously as a displacing phase. Recent laboratory relative permeability Studies have demonstrated that the flow characteristics are very different in gas-liquid systems, depending on whether gas is displacing or being displaced by, a liquid. Also, it has been shown that there is no difference between the flow characteristics of oil and water or gas and water in water wet porous rocks. The residual gas saturation that can be expected following water flooding of a gas reservoir then would be in the same range as the residual oil saturation normally expected after water flooding an oil reservoir! i.e., in the range of 15 to 50 per cent pore space, depending on the rock characteristics. Obviously, such a difference in residual gas saturation means very important differences in recoverable gas reserves from water drive reservoirs. For example, if the original gas saturation in a field were 70 per cent, and the residual gas following flooding were 35 per cent, only half of the gas in place could be recovered by complete water drive, compared to the previously expected 80 to 95 per cent. This is a situation in which complete pressure maintenance could result in very greatly reduced recovery, since straight pressure depletion recoveries from gas reservoirs can approach 80 to 90 per cent. Such a change in thinking must be based on more complete information than a series of small core tests. Hence the work reported herein was undertaken with the objective of determining whether or not residual gas saturations indicated from small core relative permeability tests at atmospheric pressure and room temperature are representative of the residual gas saturations which could be expected after water flood of natural reservoirs. A study was made both through laboratory and fields tests to determine any differences in residual saturation which might be occasioned by differences in pressure, temperature, rate of flooding, and original saturation conditions. Four separate types of laboratory experiments and two field mesurements were made in this investigation. The apparatus and testing methods of each will he discussed individually. LABORATORY EXPERIMENTS, APPARATUS AND PROCEDURE Relative Permeability Tests Steady state flow experiments Here conducted using the Penn State type apparatus. The equipment used has beer (described in a previous publication? "Irreducible" water satu-ration was established in the core' by imposing ,a capillary pressure of 45 psi before simultaneous flow of air and water

Jan 1, 1952

By AIME AIME

The following changes of address of members have been received at the Secretary's office during the period of March 15 to May 1, 1907. This list, together with the list of changes of address published in Bi-Monthly Bulletin, No. 14, March, 1907, supplements the annual list of members corrected to Jan. 1, 1907, and brings it up to the date of May 1, 1907. The names of members who have accepted election during March and April, 1907 (new members), are printed in italics. The large number of changes of address since Jan. 1, 1907; shows the importance of publishing these changes as frequently as possible, and the Bi-Monthly Bulletin has. been selected as the means to present this information to the members of the Institute. By the simple method of cutting out these names and addresses and pasting them directly over the corresponding names in the annual list of members, the record can be kept practically up to date, and the value of the list correspondingly increased. For this purpose the changes of address have been printed only on one side of the page. The names of new members, being in italics, are readily distinguished from the others, and can be pasted in approximate alphabetical order on the margins of the pages.

May 1, 1907

By K. B. McQuillin

The volume of data resulting from an intensive search for new coalfields necessitated the establishment of a computer based processing system for coalfield data. The development of this system over the past seven years is described, with particular reference to the problems encountered in both the design and operation of the data base.

Jan 1, 1977