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By B. G. Matson, M. A. Whitfield, G. R. Dysart

This paper describes the development of u computer program to calculate changes that occur in the length of tubular goods due to temperature and pressure changes during stimulation operations. Due to the numerous variables involved and the uncertainty of all static and dynamic conditions that could exist, it becomes a staggering task for individuals charged with completions to perform the necessary mathematical calculations. The computer program permits advance calculations for several sets of conditions. INTRODUCTION In the Delaware basin of West Texas alone, 50 wells were contracted or drilled to 15,000 ft or deeper in 1965. Deep well activity is continuing in this and other areas on an expanding scale. Many of these deep wells require extensive stimulation for successful commercial production, and during these operations, pressures and temperatures are encountered that have a pronounced effect on the length of tubular goods. This length change during a large-volume, high-pressure stimulation treatment utilizing fluids considerably cooler than bottom-hole temperature can be of such a magnitude that permanent damage to casing and tubing will result unless mechanical design, pressures and fluid temperatures are evaluated and controlled. These pressure and temperature effects can be calculated. However, the process lends itself well to computer solutions because of the mathematical nature of the problem and the calculating hours involved in arriving at an answer. The engineering-hour demand becomes more severe as tapered strings are involved. On initial treatments on a given well, surface pressure and injection rate conditions are unknown, and offset well conditions have not proven to be a reliable method for making predictions. For these reasons, it has become rather standard procedure for operators to compensate for these uncertainties by placing unnecessary pressure and fluid temperature restrictions on stimulation design. On a number of occasions treating fluids have been preheated to as much as 160F as a means of compensating for thermal contmction resulting from pumping cool fluids. The maintenance of packer seals has been treated by Lubinski, Althouse and Logan',' and the problem of therma1 effects on pipe has been explored by Ramey." These works were expanded and the results made applicable to everyday oilfield terminology before submitting them to computer programming. The pressure and temperature effects on tubing movement previously mentioned occur simultaneously as fluid moves through the pipe. The pressure changes, for purposes of explanation, are categorized here as to the various effects these pressures have on a tubing string. These divisions are (1) the piston-like results of forces acting on horizontal surfaces exposed to pressure, (2) swelling or ballooning of the tubing along its entire length due to the forces of pressure acting against the tubing walls, (3) the elongation of tubing due to frictional drag and (4) corkscrewing of the pipe due to internal pressure. Thermal changes are also of great importance, as their results may be more significant than any of the pressure effects. Steel is an excellent conductor of heat and the earth is a relatively poor conductor. It has been calculated that pipe temperatures at depths of more than 20,000 ft approach within as little as 25" the temperfature of the surface fluid after pumping for 2 hours, or a drop in temperature in some treatments of more than 220F. The equations presented in this paper were developed for computer programming and simplicity of input information; therefore, numerical constants such as Young's modulus for steel (28 X 10\ si), the coefficient of thermal expansion of steel (6.9 X 10."IF) and Poisson's ratio for steel (0.3) are included with unit conversion factors. The moment of inertia of tubing cross-sectional area with respect to its diameter was changed to a constant times (D' — d') where D is outer diameter and d is inner diameter. Units in the equations are length in feet, diameter in inches, density in pounds per gallon, pressure in psi, rate in barrels per minute and time in hours. PISTON-LIKE REACTIONS A change in tubing internal dimensions and the exposure of other horizontal surfaces to different pressures on the inside and outside of the tubing result in a reaction much like a piston under pressure. Such is the case when the internal diameter changes in a combination string of pipe, when seals of a slick joint assembly are subject to pressure and in the end effects of a tubing string. The change in tubing length due to the piston effects of a slick joint packer is affected by the various diameters involved, the tubing pressure Ap,, the casing pressure ,Ap,, length of pipe L, densities of fluid in the tubing before and during pump-

By D. Borman

The location of underground positions in mines has usually fallen to their survey department's. Their usual tasks include: ? installation of a high-precision peg network like the National Survey grid as beacons ? offset measurements to the sidewalls, and sometimes hangingwall and footwalls, of development tunnels and excavations ? offsetting of stoping panels for the calculation of face ? advance and the square meterage of area removed. Other departments build their observations into the plans produced by the surveyors. If more precision is required, they ask the surveyors to `elevate' their points with a theodolite. Apart from the survey peg network and `elevations' these measurements are usually planer measurements suitable for producing plans, sections and projection sheets. When the only representation medium was a sheet of paper or transparency, this was perfectly suitable. However the development of CAD models of the workings has changed all this. Full 3D representation is not properly catered for in the tool sets in current use, and needless hours are spent converting analogue-type observations into digital form. The basic survey models need to be augmented by the observations of other disciplines that are also required to locate positions underground. These include: ? the need for geologists to plott their mapping and ? borehole logs into 3D space ? the need for samplers to position their sample points accurately because the geostatistical models are biased and inaccurate ? the need for stoping width recorders to position their thickness observations to prevent errant evaluation and bonuses ? the need for rock engineers to place their mappings into 3D to build true geotechnical models to manage geotechnical stresses ? the need for production officials to receive updated face ? positions during the month so that they can manage the ? production and utilize their resources properly. This paper covers a new method of positioning profiling points to a suitable degree of accuracy. I believe the method is sufficiently simple and cheap for all to use. Historical methods Platinum and gold orebodies, especially in South Africa, are generally narrow tabular deposits. This made them suitable for depicting on a 2D medium like paper. The determination of stoping or face widths was not a problem, as the ore is removed in a single stoping process. Such 2D representations could be easily positioned using tape offsetting between survey pegs or points tied in from survey pegs. Problems of dip were handled by using 'Stope Sheets' which chose a best fit projection for the whole area depicted or by using true dip section sheets for inclined tunnels. Rolling reef and potholes were the common areas of difficulty. Most mines now model their orebody and plan the extraction in computer graphics. This means that the representation of the current workings has to change to support this trend. It now becomes a truly 3D problem. Mining officials find it inconvenient to have their actual workings in single-line depictions while their orebody is depicted with top and bottom contacts and the planned tunnels in 3D shapes. Geological models which form the basis for the resource model and planning process are often out of date, as the updating process is slow. The geological mapping has to be plotted onto sections and plans. These are then digitized into graphics by a draughtsman and checked by the geologist. Only then does the interpretation and model update take place. Potential methods to create 3D 'Actuals' Global positioning systems (GPS) Surface mines have been blessed by the advent of GPS technology. These simple-to-operate pieces of equipment and compatible software make it possible for all types of mine employees to locate themselves, and therefore to locate their observations. GPS are often inexpensive and give an acceptable degree of accuracy. Only in deep pits or close to the highwalls are observations hindered. Such technology cannot however, work underground. Ground penetrating radar (GPR) GPR is reported to be very useful for estimating the positions of potholes and faults. However it is still considered as providing an estimate, not a definite measurement. GPR is good for seeing into solid rock, not into open spaces. Inertia reading devices Experiments with inertia reading devices have been conducted on the mines. They were the forerunners of GPS for military guidance systems, and were even used for city navigation in the early 70s. They do however work best with heavy or fast-spinning gyros. Anglogold Ashanti's attempt to use them were discontinued in the mid-90s when the developers asked for an additional few million rand for a device that would weigh more than 12 kg and have a limited operational life.

Jan 1, 2006

By R. O. Williams

Analytical representation of the thermodynamics of solutions is highly desirable from the standpoint of accuracy, compactness, and numerical manipulations. In particular, computer calculations are greatly implemented. Mathematical considerations show that previous expressions have one or more serious defects. This investigation shows a Fourier series to be satisfactory but that it is also possible to derive a new series which fits certain additional conditions. Included examples show the value of analytical expressions in giving a simple characterization of each system using some two to five parameters, the elimination of the Gibbs-Duhem integration, and the es timation of the error for the experimental function as well as derived functions. It is further shown that the present characterization provides easy comparison between systems. IN the past, thermodynamic calculations have depended to a considerable extent on tabular and graphical methods. As the volume and precision of such data increase such methods become less satisfactory. Specifically, the selection of the optimum representation and the estimation of errors require statistical methods which in turn require analytical representation. The utilization of such data require further manipulations which are best done analytically for maximum precision. For example, phase equilibria are determined by common tangents to free-energy curves: a graphical determination is normally of low accuracy. As computers are increasingly used analytical representations become almost mandatory. Insufficient mathematical consideration has been given previously to the selection of empirical expressions. Those expressions having some theoretical justification are generally too inflexible and mathematically unattractive. We consider the problem in some detail and show that a Fourier series can be effectively used. Also a new series is defined which has certain advantages. ANALYSIS We wish to consider the analytical representation of the heat of mixing, AH, the excess free energy, ?Gxs, and the excess entropy, ?sXS, as a function of composition, X, for binary solutions relative to the pure components in the same state. When a distinction is not required, we use W to denote any one of the above functions. One may use a Taylor expansion around X = 0 to generate a power series. As the derivatives are un- known we represent the series as W = A + BX + CX2 + DX3 + EX4 + ... [l] where the constants A , B, C , ..- are to be selected to provide some optimum fit. For the extremes of composition W is necessarily zero so it follows that A = 0 [2a] B +C + D + E +••• = 0 [2b] Nonelectrolytes, which we are considering, appear to satisfy the condition that d3W/dx3 = 0 [3] in the terminal regions. This is the basis of the a, ß, and Q functions used by Hultgren et al.' and others. While this condition does not have a strong theoretical basis it does appear desirable that any analytical relation should satisfy this condition. Darken2 and Turk-dogan and Darken3 have shown that many systems exhibit this behavior over an extended range from each terminal region, departure being restricted to a limited intermediate region. Since we have no a priori knowledge as to where this transition occurs we can require that this condition be satisfied only as a limit at the extreme compositions as a general condition. We will show later how more restricted conditions can be included in specific solutions. Darken2 has called this behavior the quadratic formalism; we call our application the limiting quadratic formalism, LQF. This condition applied to the above power series requires that D = 0 [4a] 4-3-2E +5-4-3_F + 6 • 5 . 4G + ••• =0 [4b] The form of the power series normally used, due to Margules,4 is W=X(1-X)(A + BX + CX2 + DX3 + EX4 + •••) [5] where A, B, C, --. are a new set of constants. (Guggenheim5 has given a variation of this expression in a more desirable form. Since, however, it is contained in the above expression it does not require separate consideration.) This form is precisely what results by incorporating the conditions in Eq. [2] into the power series and regrouping the constants. The LQF requires that B =C [6a] and 4.3.2(D-C) +5-4-3(E-D) + ••• =0 [6b] Thus, the correct form of the Margules expression with two adjustable parameters is w =X(1-X)[A + B +X2-2/3x3)] 171 and the EX4 term must be included before three adjustable parameters are permitted.

Jan 1, 1970

By Wilbur I. Duvall, Wilson Blake

The microseismic method of detecting instability in underground mines was developed by the U.S. Bureau of Mines (USBM) in the early 1940's. ,3 The method relies on the fact that as rock is stressed, strain energy is stored in the rock. Accompanying the buildup of strain energy are small-scale displacement adjustments that release small amounts of seismic and acoustic energy. These small-scale disturbances, which can be detected with the aid of special geophysical equipment, are called micro-seisims or self-gene rated rock noises. It was further determined that as failure of rock is approached, the rate at which rock noises are generated increases. Thus, by monitoring a rock structure at intervals and plotting rock noise rates vs. time, a semi quantitative estimate of the behavior and stability of the structure can be made. Since sufficient use of the microseismic method is still being made by various mining and construction companies, USBM undertook a comprehensive review of the method and a study of the fundamental properties of rock noises. As all prior work on rock noises has been done with resonant-type geophones, which prevented any analysis of their vibration records, it was necessary to develop the instrumentation and field techniques in order that their properties could be investigated, such as their frequency spectrum and absorption characteristics, and to determine if both P and S-waves are generated by a rock noise. The aim of this program is the design of microseismic instrumentation which can be better utilized as an engineering tool than the presently available microseismic equipment. This new design, based on the basic properties of rock noises, should allow better utilization of these phenomena in the study and location of zones of incipient instability in both underground and open-pit mines. EXPERIMENTAL PROCEDURE To study the waveform of rock noises, it was necessary to develop a microseismic system with a broad bandwidth. To achieve high sensitivity and broad frequency response, commercial ceramic accelerometers were used. The present broad-band microseismic system consists of accelerometers as geophones, low-noise preamplifiers, high-gain amplifiers, and an FM magnetic tape recorder. This seven-channel system has a flat frequency response from 20 to 10,000 Hz, a noise level of less than 2.0 kv, and a dynamic range (including manual set attenuation) of greater than 100 db; it can detect signals with acceleration levels as low as 2 ug. The entire system is solid state and hence battery operated and portable (Fig. 1) Analysis procedures consist of playing back the 30-in-per-sec (ips) magnetic tape recordings at 1 7/8 ips to expand the time scale of a recorded rock noise event and then recording this on a high-speed direct-writing oscillograph. The oscilIographic records are then digitized and run through Fourier integral analysis computer programs to determine the frequency spectrum of a rock noise event. The oscillographic records are also examined visually to determine if both P and S-waves can be recognized in a rock noise waveform. Broad-band microseismic recordings have been made at field sites in a wide variety of rock types and in both underground and open-pit mines. Sites include the Kimbley Pit, Ruth, Nev.; the Galena Mine, Wallace, Idaho; the Colony Development Mine. Grand Valley, Colo.; the Cliff Shaft Mine, Ishpeming, Mich; and the White Pine Mine, White Pine, Mich. DATA AND DISCUSSION Analyses of the recorded data have shown that rock noise frequencies are very broad. Fig. 2 and 3 show typical rock noise events and their frequency spectrums. In addition, it is evident from these figures that the wave form of a rock noise is very complex. The wide frequency variation, 50 to 7500 Hz, is due to many variables; the effect of travel distance is the only one examined in this study. The higher frequency components of the wave are rapidly absorbed with distance or increasing travel time. Fig. 4 shows the change in waveform resulting from an additional travel distance of 195 ft. From these data, it is apparent that a resonant-type microseismic geophone cannot respond to all frequencies generated by a rock noise, and in spite of the fact that the tuned geophone is more sensitive at resonance, a geophone with less sensitivity but broader band width is much more effective in detecting rock noises. In addition, a study of broad-band microseismic records shows that both P and S-wave arrivals are easily detected, as shown in Fig. 5. All records analyzed to date show that most of the energy is in the S portion of the wave; hence, microseismic geophones should be well

Jan 1, 1970

By D. Mills, G. B. Craig

ZIRCONIUM has been float-zone-refined in an electron-beam furnace and the redistribution of oxygen, iron, and tungsten has been measured. The iodide zirconium used in the present experiments initially contained both oxygen and iron in the range 100 to 200 ppm by weight, and tungsten in amounts less than 10 ppm. Float-zone refining of zirconium, using induction heating, has previously been attempted by Kneip and Betterton1 and Langeron.2 Kneip and Betterton were primarily interested in the removal of iron and nickel. They achieved some purification, with respect to both these elements, in material given up to six passes at 150 mm per hr under an argon atmosphere. Langeron reported purification for a large number of elements after four completed passes in a static vacuum system operating at pressures less than 10-6 mm of Hg and with rates of zone travel between 30 and 40 mm per hr. He did not report oxygen concentrations, but stated that there was inverse segregation of this element. westlake5 has also used a minimum of four zone passes to remove iron from zirconium. No rates or conditions were given. Belk6 has shown that tungsten contamination can occur during electron-beam melting. He reported an increase from 0.01 to 0.05 pct by weight tungsten in molybdenum after four complete zone passes. The vacuum system for the electron-beam unit used in the present investigation consisted of a single-stage rotary pump backing a liquid-air-trapped oil-diffusion pump. A pressure of less than 10-8 mm of Hg was obtained with Dow-Corning 705 fluid in the diffusion pump. In order to avoid contamination of the zirconium by evaporation from the tungsten filament, a special focusing cage4 was employed. Three rates of zone travel, 114, 38, and 4 mm per hr, were investigated, with the liquid zone moving from the bottom to the top of the bar. The bars used were 3 mm diam and the total melted length was 130 mm. Oxygen was analyzed by neutron-activation analysis using a neutron flux of 10' neutrons per sq cm per sec to form the isotope N16 by the 016 (n,p) N16 reaction. The standard deviation is quoted for each oxygen determination. The iron and tungsten analyses were performed spectrographically, and the precision is estimated to be ±6 pct. Analyses for tungsten were all below the detectable limit of 10 ppm, confirming the protection given by the focusing cage. No significant redistribution of oxygen was found at the two higher rates of zone travel. The redistribution of oxygen and iron obtained after five passes at a rate of zone travel of 4 mm per hr (1.1 x 10-4 cm per sec) is recorded in Tables I and 11. Burris, Stockman, and Dillon3 have estimated the distribution of solutes during multipass zone refining. Using their curves for an effective distribution coefficient of Keff = 1.5 and 2 for oxygen and Keff = 0.3 for iron, the expected concentrations were estimated for the present material. These are shown in Tables I and 11, along with the experimentally measured values. The calculated concentrations are based on a molten-zone length of 10 pct of the total melted length, whereas in the present experiments the molten zone was approximately 5 pct of the total melted length. The effect of zone length on solute redistribution is most pronounced after a large number of zone passes. Comparison with Pfann's published data8 for solute redistribution for various Keff's and zone lengths indicates only small differences at low numbers of completed zone passes. It is evident that the expected distribution has not been realized in the case of iron. Scrapings of material deposited on the inner surfaces of the electron-focusing cage were found to be magnetic. It is, therefore, concluded that redistribution of iron is masked by evaporation. Deposition of iron inside the focusing cage was observed at all rates of zone travel. The results of the investigation may be summarized as follows: 1) Segregation of oxygen is typical for a solute with a distribution coefficient, Keff > 1. 2) No redistribution of oxygen takes place at high rates of zone travel. 3) The distribution coefficient for oxygen lies between 1.5 and 2.0. 4) Purification with respect to iron occurs mainly by evaporation. 5) The focusing cage is effective in preventing tungsten contamination.

Jan 1, 1967

By H. H. Klepfer, K. J. Gill, P. Chiotti

SOME observations relative to the U-Zn system have been made by other investigators. Chipman1 and Carter2 have reported the preparation of several U-Zn alloys and point out that these alloys are generally difficult to prepare. Chipman1 reported evidence for a high melting compound at about 90 atomic pct Zn and the possible existence of a eutec-tic between the compound and uranium. Raynor," in a theoretical discussion of the alloying properties of uranium, included zinc among the elements predicted to have little or no solubility in a, p, or y uranium. In the present investigation, thermal analyses, X-ray, metallographic, and vapor-pressure data were obtained to determine the phase boundaries. The relatively high zinc pressure over most of the alloys at temperatures of 900 °C and above proved troublesome and special techniques had to be employed in preparing suitable alloys. Materials and Preparation of Alloys The metals employed in this investigation were Ames Laboratory biscuit uranium containing less than 500 ppm total impurities and Bunker Hill slab zinc or Baker Analyzed reagent granulated zinc, both with a purity of 99.99+ pct. Due to the high vapor pressure of zinc and the high reactivity of both uranium and zinc with oxygen at only moderately high temperatures, alloys were prepared in closed containers which had either been evacuated or evacuated and filled with helium. High purity magnesia, magnesia containing 10 pct calcium fluoride, and tantalum proved to be suitable crucible materials. Tw-o different procedures, described below, were used to prepare alloys, the latter being the most satisfactory. The metals, uranium turnings and granulated zinc, were cleaned with dilute nitric acid, rinsed, dried, and placed immediately in a helium-fill'ed dry box. The two metals were placed' in a 10 mil Ta crucible. The charge was enclosed in the tantalum crucible by welding on a preformed tantalum cap. This assembly was enclosed inside a stainless steel (AISI 309) bomb. The bomb was made by welding a piece of stainless steel plate on each end of a stainless steel pipe. All these operations were carried out in a helium atmosphere. These assemblies were heated in a muffle furnace at temperatures between 1100" and 1200°C for 10 to 15 min or held as long as 15 to 20 hr in the 950" to 1000°C temperature range before quenching. Spectrographic and chemical analyses showed no tantalum pickup by the alloys, indicating no reaction between the alloys and the crucibles. However, some of these crucibles failed, probably due to imperfections in the welds of the stainless steel or tantalum crucibles. The second and most satisfactory method was to prepare the alloys by powder metallurgy techniques. The procedure was to press degreased and acid-etched uranium turnings with granulated zinc into 20 g compacts under 20,000-psi pressure. The compacts were placed in MgO crucibles, and sealed in evacuated Vycor or fused silica tubes. The alloys were then heated as long as two weeks at about 550°C in a muffle furnace. The pressed compacts were observed to expand by several volume percent during heating and it was necessary to make allowances for this expansion in order to avoid breaking the crucible and Vycor tube. This method was found very satisfactory for preparing alloys which were suitable for thermal analysis or vapor pressure studies. Experimental Methods and Results The phase diagram for the U-Zn system at 1 atrn pressure, shown in Fig. 1, is based primarily on vapor pressure measurements and on thermal analysis taken at temperatures below 950°C. Fig. 2 shows the U-Zn diagram at 5 atrn pressure, constructed on the basis of thermal analysis of alloys in sealed containers up to 1150°C and on the basis of metallographic, X-ray, and analytical data. The alloys sealed under vacuum were actually under their own vapor pressure and those sealed in an atmosphere of helium were under an additional pressure due to the helium. At temperatures up to 1100°C the zinc pressure is 5 atrn or less for these alloys; consequently the maximum pressure over the alloys sealed under a helium atmosphere was 10 atrn or less at temperatures up to 1100°C. Changes in pressure of this order of magnitude do not appreciably alter the position of most solid-solid or liquid-solid phase boundaries. In constructing the phase diagram for a pressure of 5 atm, the effect of pressure on all phase boundaries except those for liquid-vapor or solid-vapor regions was considered negligible.

Jan 1, 1958

By D. S. Tomalin, D. F. Stein

The effect of reducing oxygen to low concentrations on the fracture of high-purity iron single crystals has been examined at 78° and 20°K. It is found that iron single crystals grown by the strain-anneal method usually contain a few occluded grain boundaries which may become embittled in the presence of oxygen, thereby nucleating cleavage fractures. High purity with respect to interstitial elements was found to inhibit twinning and evidence is presented for an orientation dependence of the resolved yield stress. Deformation occurred by slip rather than twinning at both temperatures of testing with elongations of as much as 9 pct at 20°K. THE fracture properties of iron single crystals have been observedl-3 to be a function of temperature, orientation, and purity. Allen, Hopkins, and McLennan1 demonstrated that at 78°K iron single crystals became increasingly brittle as the tensile axis approached the (001) pole of the stereographic unit triangle. Iron crystals with the tension axis near a (001) pole were completely brittle and orientations near the (011)-(111) boundary were very ductile, achieving a 100 pct reduction in area prior to fracture. Later work of Biggs and pratt2 and of Edmondson3 demonstrated that by reducing the carbon content of the single crystals the transition between brittle and ductile failure at 78°K could be shifted to orientations nearer the (001) pole. Ed-mondson went further and pointed out that any mechanism which tended to increase the yield strength of the iron (i.e., carbon addition, pre-strain) also increased the tendency for brittle behavior at 78°K. Thus by a reduction of carbon content Biggs and Pratt were able to obtain ductile behavior to within 20 deg of the (001) pole, and Ed-mondson was able to obtain ductile behavior to within 26 deg of the (001) pole. Edmondson's material had a total interstitial content (carbon, oxygen, and nitrogen) of approximately 60 ppm and, although Biggs and Pratt reported no analysis, indications were that their iron contained comparable impurities. Stein, Low, and seybolt4 purified iron single crystals to a total carbon, oxygen, and nitrogen content of approximately 20 ppm. They observed a lowering of the yield stress with this increased purity, and thus one might have expected an observation of increased ductility. Although they tested specimens of orientations which the previous workers had indicated should be ductile, the crystals failed at a 78°K in a brittle manner with little elongation. Stein noted,' however, that about 90 pet of the failures could be traced in origin to occluded grains. Allen et al.1 and Edmondson3 do not report examination of their cleavage surfaces, but Biggs and pratt2 reported that microscopic examination of the cleavage surfaces of many of their specimens revealed the presence of small occluded grains. Honda and cohen6 and Keh7 have also observed the initiation of fracture at occluded grains in iron single crystals. Therefore, the additional complication of occluded grains must be considered in studying the properties of iron single crystals and the origin of fractures determined if the ductility exhibited by the crystals is to be considered meaningful. Various investigators8-12 have studied the effects of impurities on grain boundaries in high-purity polycrystalline iron. Rees and Hopkins10 showed that the addition of oxygen to low-carbon (0.002 pet) iron weakened the grain boundaries, causing a shift from transcrystalline to intercrystalline fracture and a progressive decrease on the brittle-fracture stress with increasing oxygen content. In addition, it has been shown by Low and Feustel11 that the addition of carbon to polycrystalline iron containing oxygen eliminated grain boundary brittleness. Thus, oxygen can embrittle grain boundaries in high-purity polycrystalline iron, but the addition of an appropriate amount of carbon can eliminate the oxygen-induced brittleness. The oxygen content (19 ppm) of the iron "single crystals" employed by Stein el al. was large enough to suspect impurity effects at the occluded grain boundaries. Allen et al.1 Biggs and pratt,2 and Edmondson3 may have masked any occluded grain problem in their specimens considering the relatively high carbon levels they employed. stein13 demonstrated that the addition of as little as 0.9 ppm C to previously purified (less than 5 x 10-3 ppm C) "single crystals" would increase the elongation from a few percent to more than 20 pet at 78°K and the fracture was not associated with grade boundary initiation.

Jan 1, 1965

By C. J. Guntner, R. P. Reed

A commercial 18Cr-8Ni iron alloy (AISI 304L) was examined in tension at 300°, 76°, 20°, and 4°K. Continuous stress-strain recordings were made, X-ray analyses at periodic stress (strain) intervals were obtained, and the magnetic measurements were taken. From this data the percentage of martensitic products [bcc(a) and hcp (E)] was computed as a function of stress (strain). It was found thatup to 15 pct E phase forms at low temperntures. The amount of E formed increases to a maximum at about 5 pct strain, then decreases. This decrease indicates the additional transformation of E to a'. The total amount of E and a' was suppressed at constant stress (strain) at 4°K as compared to 76°K. It is proposed that the suppression of E and a' is associated with the decreased mobility of extended dislocations at very low temperatures. The yield strength decreased as the temperature was depressed below room temperature and then increased rapidly near 4°K. SOME ferrous alloys which are austenitic (fcc ?) at room temperature appear to be unique in that two martensitic products (hcp e and bcc a') may form on cooling to lower temperatures or on application of mechanical stress. The most common room-temperature austenitic ferrous alloys are 18Cr, 8Ni stainless steels. Most aspects of the spontaneous transformations have been previously described for these steels.' Several previous papers have described special aspects of the stress-induced transformations at low temperatures for the stainless steels, such as the existence of the hcp phase (c) after straining at 76oK,2-7 the morphology after straining using electron microscopy,7 and the decrease in E at higher strains at 76oK.4 However, for a complete representation, one must know the stress-strain characteristics and the dependence of both martensitic products on applied stress and temperature. It is the intention of this paper to provide that documentation. To accomplish this, continuous stress vs strain recordings were made at four temperatures: 300°, 76", 20°, and 4°K for annealed AISI 304L (a commercial 18Cr-8Ni alloy). At periodic stress intervals at each temperature the integrated X-ray line intensity of a selected peak for each phase (y, E, and a') was measured. In addition, photomicrographs of the strained surfaces were taken and magnetic measurements were made. The magnetic readings can be directly converted into percent a'.',e With these measurements the percentage of each phase may be plotted as a function of stress (or strain) and test temperature. It was found that up to 15 pct E phase forms upon stressing the AISI 304L alloy at low temperatures. The E percentage increases abruptly after the alloy yields, but then decreases gradually at higher stresses. The rapid increase in e at 76°K is associated with an "easy-glide" portion of the stress-strain curve. The total amount of a' + .G is suppressed below 76°K at a constant stress or strain. The yield strength decreases down to 76°K but increases rapidly below 20°K. EXPERIMENTAL PROCEDURE Tensile test specimens were cut parallel to the rolling direction from 0.1-in.-thick sheet. Continuous stress vs strain recordings were obtained at each test temperature (300°, 76o, 20°, and 4°K) using equipment and methods described elsewhere.' The specimens which were used in the X-ray analysis were stressed to successive increments of strain at each temperature, analyzed at room temperature, then restressed at the test temperature. This procedure was repeated until approximately ten X-ray analyses had been performed with approximately 1.0 pct strain increments. The specimens had a reduced section 1 in. long, 1.2 in. wide, and 0.1 in. thick. They were electro polished prior to testing and after each strain increment. Table I lists the chemical composition, grain size, and hardness for the alloy which was used. This is the same alloy for which extensive mechanical-property tests3 and morphological studies of the spontaneous transformations' have previously been made. For the low-temperature tests (76o and 4°K) below the Ms temperature the specimens were initially cooled to the test temperature, held for 1/2 hr, then warmed and X-rayed at room temperature. The results are listed in Table 11. From earlier work8 it was known that additional transformation on the second cycle would be considerably less (-0.1 pct

Jan 1, 1964

By G. E. Perry, J. F. Bruskotter, D. G. Russell, J. H. Goodrich

The depletion performance of gas wells has been investigated by mathematical simulation techniques. The gas well model which was studied consisted of a single well located in the center of a bounded, cylindrical, homogeneous reservoir. Dependency of gas compressibility and viscosity on pressure was considered in studies of well performance at both constant mass flow rate and constant flowing pressure conditions. To carry out the investigation, the nonlinear, second-order, partial differential equation which describes Darcy flow of a nonideal gas through porous media was solved numerically. Some of the previous investigations of gas well performance have been of limited general use, because assumptions were introduced to simplify either the gas properties or the basic differential equation. Other studies have been rigorous in these respects but have presented a very limited set of calculated results. The present study was attempted to present a rigorous theoretical model and sufficient numerical results to permit meaningful conclusions to be drawn. It was found that all terms must be retained in the partial differential equation to make accurate predictions. The neglect of higher-order terms, e.g., terms of the order of the "gradient squared", leads to serious material balance errors at large times and to conservative estimates of gas well performance. The higher the gas flow rate and/or the lower the permeability-thickness product of the formation, the more pronounced are these deviations. For example, in a well draining 640 acres in a 25-md-ft formation (8,120 MMcf gas in place) at a constant rate of 993 Mcf/D, the rigorous solution predicts a bottom-hole pressure decline from 4,000 to 1,000 psia in 8.7 years. If higher-order terms are neglected in the differential equation, this decline in pressure is predicted to occur in 5.3 years. With the results of the numerical solution of the differential equation as a basis, simple, easy-to-use approximations for predicting gas well performance for Darcy flow conditions have been developed. These simple approximations are based on the familiar equations for flow of a single, slightly compressible fluid. The approximate methods possess a high degree of accuracy and enable the prediction of long-term gas well performance to be made quickly and accurately without the use of a digital computer. Both transient and stable flow period approximations were developed. INTRODUCTION In recent years income from the sale of natural gas and associated products has represented an ever-incre as ing fraction of the industry's total revenue from operations. To meet the surge in demand for natural gas, the industry has depended heavily upon established reserves and has actively pursued development of new reserves. The search has progressively led to reservoirs which yesterday were too tight and/or deep to yield the desired return on invested capital. More than ever before, evaluation accuracy is now required to forecast the criteria upon which engineering recommendations and management decisions are based. Considerable effort has been expended by both research and operations personnel on the development and application of methods for analyzing and predicting the performance of gas wells. Fundamentally, the problem is the familiar one of extracting data during the drilling, testing and early production life of a well and applying these data within an accurate simulation model to predict long-term behavior. During the past 30 or more years a voluminous literature dealing specifically with gas field problems has been generated. A recent book' lists a comprehensive bibliography of published material through 1959. Over 1,200 references are cited. Since then 39 additional articles on natural gas technology have been published in Transactions volumes of the Society of Petroleum Engineers of AIME. Most existing theory for predicting gas well performance requires that one or more idealizations (e.g., steady-state flow, ideal gas of constant viscosity, small and constant compressibility and constant-viscosity fluid) be applied. Although existing theory may apply directly or be adapted by various artifices to describe specific gas well and reservoir behavior, no widely applicable method is available, and existing methods appear to be subject to appreciable error unless better limits of applicability are defined. The objectives of this paper are (1) to present numerical solutions to the partial differential equation describing gas flow under conditions of general interest in gas well performance prediction work, (2) to present solutions which possess a high order of accuracy for both transient and stabilized flow periods of a well producing at constant rate or constant pressure, and (3) to develop and present simplified relationships which can be used as high-order approximations to the exact numerical results for fast and accurate predictions of gas well performance at the operating level. Combined, these objectives are designed gen-

Jan 1, 1967

By Jon Hurt

INTRODUCTION The entire scope of new facilities for Lake Mead Intake No. 3 includes a sub-merged intake structure, a deep tunnel beneath Lake Mead, a tunnel access shaft, Intake Pumping Station No. 3, and connections to an existing intake and water treat-ment facility, as shown in Figure 1. In March 2008 Vegas Tunnel Constructors (VTC), a joint venture of Impregilo SpA and SA Healy were awarded a $447m Design-Build contract by SNWA for a section of this work (Contract 070F 01 C1), including the 185 m deep tunnel access shaft, the 4.7 km long, 6.1 m diameter tunnel and the submerged intake. Arup, supported by Brierley Associates, is the Design Engineer for VTC. The scope of the work is shown in Figure 2. This paper will describe the design and construction on this contract, with a focus on the access shaft which is the most complete section of the work. The shaft is being sunk using drill-and-blast methods with the finallining placed as excavation proceeds. The shaft passes through a major fault zone, and extensive pre-excavation grouting for water control is required for much of the depth of the shaft.

By Gordon Demetrick

3900 Yonge St. was not a typical site on which to build a condominium apartment. A steep hill covered the majority of the site. In order to use as much of this site as possible, the rear of the building was to have nine stores cut into the face of the hill. A permanent shoring system was required as the building structure was not designed to provide sufficient stabilizing elements to support the total earth pressure. The total excavation depth required was 36 m (120'-0") with the upper 12 m (40'-0") to be backsloped. The vertical face of soil to be supported was 24 m (80'-0'). The shoring system originally designed by the Structural Engineer was to support this face by installing soldier piles and inclined earth anchors. During bid preparation it became evident to us that the system as designed would be difficult and expensive to install due to wet soil conditions. An innovative design was required to overcome these problems. Anchor Shoring hired John Stephenson Consultants Ltd. to aid them in accomplishing this goal. After extensive investigation together with The Trow Group, a unique design was proposed which provided a practical solution to the shoring problem.

Jan 1, 1987

By M. Sanchez, C. Morales, J. Palacios

The slag produced in the Peirce Smith converters at the Ilo smelter of Southern Peru Copper Corporation has shown a wide range of magnetite content, which introduces an additional problem in the smelting units due to materials? recirculation. However, the operation data analysis and the application of thermodynamic concepts have made it possible to produce slag with magnetite content between 18 and 20%. The results have suggested that matte grade enhances magnetite formation while silica controls its precipitation, and they are also influenced by the increasing temperature of the slag. Thus, in order to obtain the required magnetite content in the slag, matte grade is gradually enriched in equilibrium with slag containing from 25 to 32% silica.

Jan 1, 2004

The sphere of operations of dry crushing has been so much enlarged of late years that the following notes with reference to its advantages and limitations, and also some practical results in connection with the crushing of gold ores will probably be of service to the members of the Institute. Until recently, with one notable exception that of the Mt. Morgan Gold Mine, dry crushing has only been practiced to a very limited extent in Australasia, and elsewhere it might be said to belong to industries other than mining Its sphere of usefulness depends on the fact that the' product is delivered in a dry state without the separation of the finer particles from the coarser to any appreciable extent, thus enabling the following advantages to be achieved with different ores.

By M. Yavuz

The use of natural stones like marble is approximately as old as the emergence of human. Marble and natural stone usage of Turkey also dates back to very old times. Marble is produced in Anatolia since the ancient times. The archaeological excavations made in Anatolia indicate that the modern methods that are used for the production of marble blocks in modern world were first used by Anatolian people. Turkey is one of the oldest natural stone producers with its 4000 years of production history, starting from the Marmara Island. Therefore, the territory of Turkey possesses 4000 years of natural stone processing technology and experience. Turkey has fairly richer reserves of marble compared to other countries. This is why the rich and quality marble deposits of Turkey are resembled to the appearance of the Alpine-Himalayan marble belt of the world. Turkey has almost 40% of the total marble reserves (13.9 billion tones) of the world with 5.2 billion tones. Turkey?s marble reserve?s monetary value is worth about 2 trillion dollars. However, only 1% of these reserves are currently being utilized.

Jan 1, 2011

By E. C. Lane

"In a previous paper the Bureau of Mines. 3/ presented in condensed tabular form all analyses of Texas crude oils made by the Bureau up to March 193K. This previous report states;The first Al well in Texas was drilled near Oil Springs, Nacogdoches County, in 1863-67. However, the first oil field of major importance in the State was discovered at Corsicana,Navarro County, in 1895. Since that time the petroleum industry try in the State has spread and grown until today petroleum from Texas is an important commodity in world petroleum markets.Since March 1939 samples of Texas crude oils from many new fields, and some older fields not covered in the previous report, nave been analyzed. Those analyses arc reported in the present paper. The annual production by years from 1896 to 1940, inclusive, taken from the figures in the Bureau of Mines Minerals Yearbook, are given in table 1. Production for 1896-1940, inclusive, totals 6,579,715,000 barrels.Various authors reported upon developments and production in the Texas fields in the Transactions of the American Institute of Mining and Metallurgical Engineers, Petroleum Division, for 1941. 4/"

Apr 1, 1943

By Richard H. Johnson

The Castle Mountain Mine (CMM) is located in the eastern por­tion of San Bernardino County, Southern California, 70 miles south of Las Vegas. The CMM is a joint venture between Viceroy Gold Corp. (75% and operator) and MK Gold (25%). The CMM initially started gold production with an 8,000 tpd cyanide heap leach operation in February, 1992 when the first ore was crushed and delivered to the leach pads. Even during construction and commissioning, design work was under way to engineer and construct a 1,200 tpd Mill circuit to process the higher grade fraction of the ore through use of pulp agglomera­tion. The need for a grinding circuit became evident with the quantity of high grade material delineated during drilling and the amount of visible gold that the geologists were finding in the drill core and R.C. cuttings. Viceroy did not want to stack the higher grade ore on the heap, and it was clear that permitting a tailings pond would, at best, be a long drawn-out affair. An alternative to a tailings facility had to be found.

Jan 1, 1996

By O. C. Blade, E. L. Garton

Louisiana is one of the major oil-producing States of the country. Commercial production of crude oil in the State began in 1902 and has increased to an estimated output of 157,409,000 barrels in 1945, which is the maximum production up to this time and places the State fourth in the nation. The cumulative production for Louisiana through 1944 is 1,544,481,000 barrels, and, adding the output for 1945, the total to January 1, 1946, is 1,681,890,000 barrels. Data on annual production of crude oil in Louisiana and tentative statistics for 1945 are given in table 1. The large production of crude oil in Louisiana and the present trend to utilize petroleum in accordance with its general characteristics make it increasingly important to present analytical data for crude oils. This report is the fifth of a series presenting such data obtained on crude oils from Louisiana according to the procedure used by the Bureau of Mines. Individual analyses are given for 82 samples from 64 fields; many of the samples are from recently discovered fields, and some are from new producing formations.

Dec 1, 1946

A special committee on the Classification of Surface Mining Methods was appointed by the A.I.M.E. Board of Directors on Nov. 17, 1939. The committee was headed by Gerald Sherman, and the members were Chester A. Fulton, C. F. Jackson, Earl E. Hunner and Arthur Notman. The following form of classification was reported to the Board by the Committee on May 16, 1940, as its unanimous recommendation. SURFACE MINING Dry Mining Bottom Benching Bank Mining < Top Benching Dry Mining Dry Mining Bottom Benching Hydraulic Mining Pit Mining Dredging Dry Mining Top Benching Wet Mining Top Benching River Bed Dredging Subaqueous Mining Lake Bed or Dredging Ocean Bed (Hand Mining Ground Sluicing Hydraulicking Dredging In most cases the terms used in the accompanying outline define themselves. Bank Mining is distinguished from Pit Mining by its situation. In Pit Mining the ore is taken from an operation below the level of the surrounding surface. In the secondary classification, Bottom Benching is an operation in which a bench is attacked from below, but the material mined might be hauled up out of the pit or moved out horizontally or downward.

Jan 1, 1940

NIM reports Report No. 1615 Fluorspar pellets. A survey of the world market and an assessment of future South African production. Report No. 1621 Correction for matrix effects in the analysis of solutions by X-ray-fiuorescence spectrometry. Notices Questionnaire on Technicians The Department of National Education&apos;s committee of enquiry into the education, training, utilization, and status of engineering technicians in the Republic of South Africa was established as a result of Resolution 6.3 taken at the Sixth Conference on Engineering Education: The Education and Training of Engineering Technicians. Vraelys oor Tegnici Die Departement van Nasionale Opvoeding se komitee wat ondersoek instel na die opleiding, gebruik en status van ingenieurstegnici in die Republiek van Suid-Afrika is gestig as gevolg van Besluit 6.3 wat geneem is tydens die Sesde Konferensie oor Ingenieursopleiding: Die Opleiding van Ingenieurstegnici. Competition for Student Members of the South African Institute of Mining and Metallurgy Each year the Institute offers a prize (or prizes should the entries warrant it) of up to R100 for the best paper or dissertation on a topic appropriate to the interests of the Institute. The competition is open to all Student Members of the Institute.

Jan 8, 1974

By M Kuruppu

Large mining operations require a high percentage of the capital invested in mobile and fixed mining machinery. From an investment point of view this expenditure must be met by an equally high rate of return, thus the need for high plant and equipment reliability is of major importance. Equipment downtime is undesirable and very costly, resulting in lost production and revenue, which is of critical importance to successful mining operations. One of the solutions to this problem may be found in the form of competent computerised maintenance management software systems, which help to reduce the problem of breakdowns. These software assist the engineers for the management of service orders, resource allocation, progress monitoring as well as costing. They also facilitate the communication of targets and objectives among the service personnel. A computerised maintenance management software called MAINPAC was used to record and plan the activities of mobile equipment maintenance in a large mining operation in Western Australia. Among the details recorded were equipment data, service history, machine downtimes, previous maintenance, job planning and the resource required. This information further helped to analyse the maintenance efficiency, availability and the reliability of the equipment.

Jan 1, 2006