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The old De Beers mine, which lies northwest of Dutoitspan mine at Kimberley, was the mine which launched Cecil Rhodes (In his historical career. It was the nucleus of the De Beers Mining Co. Ltd., formed in 1880, which later became De Beers Consolidated Mines Ltd. Inactive for more than a half century, the De Beers Mine is being rejuvenated for a new era of operations. Both mines were on the Vooruitzicht farm owned by the De Beers brothers, who had bought it from the Orange Free State Government ten years previously for £50. Although the brothers sold it soon after the discovery of diamonds at Dutoitspan, they are remembered for having given their name to the foremost diamond mining company in the world. Diamonds worth nearly R180,000,000 have come from this ground, and more will be recovered when the mine is re-opened.

Jan 9, 1963

By George S. Lockwood

Plans are moving ahead toward the July 1965 start-up date for Kaiser Steel Corp.’s new pelletizing plant at its Eagle Mountain, Calif., iron mine. Capacity will be 2 million long tons of pellets containing 65% Fe. A major portion of the output is scheduled for charging into Japanese blast furnaces as the result of a contract to supply Mitsubishi interests with 10.8 million tons of pellets over a six-year period. Kaiser's concentrating plant at Eagle Mountain plus sintering facilities at Fontana are adequate to meet the requirements of its blast furnaces, which, as a consequence, are not expected to take any substantial quantity of pellets during this period. However, some 200,000 tons of pellets per year is scheduled to be used for the production of special steels and in the open hearths as a substitute for the high-cost ores now being used.

Jan 8, 1964

By H. W. Camp

Although the situation in the oil industry during the past year has not been conducive to large expenditures for development and research, there is little indication that such expenditures have been curtailed. While few outstanding achievements have been reported, considerable progress has been made in the development of new product,s and the adaptation of petroleum derivatives to new uses. The most important question facing the refiner today is the antiknock quality of his gasoline. This year has seen the widespread adoption of the term "octane number" as a measure for anti-knock values, and in the latter months of the year the public has been made acutely aware of this condition through competitive advertising. Gasoline is no longer priced on volatility and gravity alone, but on octane number as well; and premiums are being paid for material of relatively high octane rating. The situation has grown more and more competitive and has forced refiners continually to raise the octane rating of their regular and competitive grades, and at this writing the same situation exists for premium grades which have possessed relatively high anti-knock properties for some time. Straight-run gasoline produced from paraffin-base or semiparaffin-base crudes has an inherently low anti-knock value, and in order to convert this material to a higher quality it has been found necessary to crack an increasing percentage of the crude oil charge. By completely cracking the heavier portions of the crude and blending back with the straight-run gasoline, it has been possible to produce an average of 63 to 65 octane number gasoline on average Mid-Continent crude. This operation carried to the fullest extent does not suffice, however, and the recent and rapid development of the so-called '(reforming unit," has resulted. The straight-run gasoline fraction is cut into two parts: a light, low boiling point gasoline; and a heavy gasoline or naphtha. The latter containing the low anti-knock portions of the gasoline, is sent through a re-forming unit and subjected either to high temperature or pressure, or both, which materially increases its octane number. On average Mid-Continent the blend of low boiling point straight-run,

Jan 1, 1932

By Henry M. Howe

1. The purpose of the National Research Council as organized for war purposes is twofold, to stimulate those outside its own personnel to conduct researches of importance for winning the war and to carry on such researches through its personnel to a limited extent. How this is done is explained in Section 10. "Research" is used here in a very broad sense, including, for instance, inventing and developing mechanical and physical devices. The need of this work arises from the inevitable concentration of most of the governmental war agencies on the production and transportation of war materials of the types now adopted, as distinguished from devising new kinds of instrumentalities, such as armor, guns, aircraft, and apparatus for detecting, locating, observing, signaling, transporting, and many other military purposes. But it is important that we should devise new agencies. The war came near being won by an invention, the submarine, and its course has been affected greatly by two other inventions, tanks and aircraft. In spite of our numerical superiority victory may well be snatched from us by an invention, if we allow Germany to outstrip us in inventing. Hence the importance of the Council's work in mobilizing and organizing the services of the patriotic civilian experts throughout the country, so as to bring their powers to bear on important war problems and on inventing war devices, as an adjunct to the development work of the regular governmental bodies. 2. Status of the Council.—Though President Wilson's request caused the Council to be created in 1916 by the National Academy of Sciences under its congressional charter; though his executive order of May 11, 1918, directs the heads of "Governmental departments immediately concerned" to "continue to co-operate with it in every way that may be required;" and though the Government has contributed largely to its financial support; it is not a department of the Government but an independent research body, aiming to evolve the necessary mechanism for the novel work of systematic stimulation and guidance of research. Thus the Government, which instigated the creation of the Council, recognizes and collaborates with it, and in part supports it. The Council acts moreover as the Department of Science and Research of the Council of National Defense.

Jan 1, 1919

By J. P. Lesley

The old do not love to see the young pass away from the light of the sun before them. Fathers would fain keep their sons by their side to the. end of life ; but the old Greeks, who loved the old gods, were wont to moderate their grief with the sweet superstition that only those whom their gods especially loved died early. The Christian church found consolation in that superstition applied in a new form to its new sorrows, and paid its most enthusiastic devotion to the memories of its young and beautiful martyrs. The natural science of our century is robbing us fast of this and all other superstitions, sweet as well as bitter, and leaving us for consolation to the teaching—colder, yet kinder—of personal fortitude and that optimism Which intelligently translates the Cosmos of Humboldt back into its old name of the Harmonia of Pythagoras. The Homeric Kataclothes, the three fates, are dead and gone for us, with that old world which comprehended none of the laws of cause and effect, and sorrowed for those who were cut off from the land of the living without hope of more than a shadowy existence beyond the river of death. All the more the ancients cherished the memory of their dead and lavished their choicest art upon their monuments. We moderns have lost the monumental arts, but we better keep the monuments which our dead leave behind them. No one of us who has done good work can fail to be remembered; and in an Institute like this, which keeps the press at work, an immortality in the memory of men is more possible, more certain, for every one of its members than the greatest heroes of antiquity could anticipate for themselves. In old apocalyptic times the works of men followed them through death to the throne of God to be their advocates in judgment, but in these modern times our works remain this side the grave, to follow the name of the departed one as it takes its course along the history of his peculiar art or science advancing slowly to perfection. We write the epitaph, not upon the mouldering stone of a tomb, but on the pages

Jan 1, 1890

By [Dipl. -Ing. ] Karl Angerer

The "New Austrian Tunneling Method" is one of the most significant developments in European tunneling in the last 15 years. I hope this report will show the significance of this tunneling method, which was developed in Austria exactly 18 years ago and which is now used in many European countries. In Austria from 1948 to 1953, the Moll tunnel with a length of 11.6 km (about 7.3 miles) was constructed as a part of the Kaprun power plant. Depth of overburden varied from 1000 to 1400 m, and there were many rock bursts in calcareous-schist formations. Here for the first time it was found that a thin concrete lining would help to prevent rock bursts if it was sprayed on the rock soon after blasting. During construction of the Prutz-Imst tunnel in Austria from 1953 to 1956, the shotcrete lining was sprayed on the phyllite surface a certain distance behind the blasting face to prevent rapid rock decomposition. This method was also tried in soft-rock sections of the tunnel where steel and wood supports usually were necessary. To prevent loosening of the rock, application of the sprayed concrete was tried immediately after blasting. This method made it possible to tunnel through very soft ground. Where necessary, the shotcrete was supplemented by steel arches and mesh reinforcement. At that time (1953-1956), the machines and equipment for guniting or spraying concrete were being improved rapidly and it became possible to spray aggregates up to 25 mm in diam. Hardening accelerators brought quicker strength and better adhesion of the shotcrete-this also made it possible to use the method in wet tunnels. If the tunnels are extremely wet or flowing with water, it is necessary to seal off the wet rock or drain the water, using, for instance, the Oberhasli method. After these first successful steps with the new Austrian method, large portions of the Schwarzach power plant in Austria were designed and built. At this operation, shotcrete was used almost exclusively for tunneling work. It was on this site where, for the first time, a tunnel 120 m long with a 45-sq- m section was driven through overburden without one piece of timber

Jan 1, 1970

By J. D. Wheeler, H. W. Mathews

The increased activity in West Texas, which started in 1933, has continued through 1936 at a constantly accelerated rate. During 1936 there were 1442 wells completed in the area as compared with 700 in 1935 and 468 in 1934. Of these completions, 1313 were producers with a total 24-hr. potential in excess of 1,750,000 bbl. From among the 1442 wells, eight are considered to be discovery wells for new West Texas fields. New Fields Bennett.—The Bennett field, which added Yoakum County to the oil-producing counties of West Texas, was actually indicated as an oil-producing area during 1935, but the discovery well, Honolulu Oil Corporation, Ltd. and Cascade Petroleum Company's Bennett No. l, was not given a production test until April 1936. The discovery well made 15 bbl. per hour through 3/4-in. choke with a plugged-back total depth of 5264 ft. First oil in the hole was from 5088 to 5090 ft., which is several hundred feet below the top of Permian lime. Producing limits of the field are unknown, as the second test had not reached the pay at the close of the year. Henderson.—-To date indications are that the Henderson pool, in northern Winkler County, is the most prolific area opened during 1936. This field, which lies to the north of the old Hendrick pool, is producing from the same reef-type dolomitic lime producing in the older field. The Henderson field was opened by the completion of R. H. Henderson, J. B. Walton-Humble 1-A in April 1936 for a natural flow of 2306 bbl. per day through tubing. Total depth of the discovery well is 3049 ft. Later development has indicated the productive area to be a rather narrow zone running slightly west of north. Present area of from 1000 to 1500 acres has been proved for production. Keys and Emperor.—The Keys and Emperor pools in the belt of sand pools running across Winkler County appeared for the first time on State proration schedules during 1936. This report considers these pools as links in joining the belt of sand production across Winkler County, for

Jan 1, 1937

By P. K. Foster, C. M. Payne, A. McNabb

Some measurements of the rate of loss of hydrogen from cylinders of iron and steel are analyzed in terrns of a trapping theory. The apeement is encozcraging and gives rise to estimates for the density of traps in the metal. Furthermore, the results appear to be consistent with the assumption that the diffusion constant D for the steady flux of hydrogen through iron lies on the extrapolation of the linear curve (log D us 1/T) obtained at higher temperatures. IT has been shown in a previous paper1 that the literature relating to hydrogen diffusion in steels contains sufficient evidence to invalidate the application of Fick's laws to hydrogen diffusion in steel at low temperatures. To account for the deviations from simple diffusion behavior a trapping theory was developed, and the fundamental laws modified accordingly. In the present paper, new data on the evolution of hydrogen from long cylinders are presented, and together with some published data are examined in terms of the requirements of the theory.' Properties of solutions of the basic equations derived previously1 and appropriate to the present experimental conditions are outlined in the first section as they determine the form in which the experimental data must be presented for a comparison of theory and experiment. Two new solutions not previously reported have been derived as described in the Appendix. The experiments and treatment of data are then given in Sections 2 and 3 and the results are discussed in Section 4. 1) THEORETICAL CONSIDERATIONS The hydrogen-diffusion theory1 applied in this paper postulated that lattice-dissolved hydrogen at a concentration C diffuses randomly in accordance with Fick's first law, but that the lattice contains a uniform density N of traps which can capture and delay hydrogen atoms. kC atoms are trapped per second in a region containing unit concentration of vacant traps while p are released per second in a region containing unit concentration of occupied traps. On this basis it was shown (Eq. [30] of Ref. 1) that, when local changes in the lattice-dissolved concentration C are slow enough for equilibrium to be established with the traps, the system is represented in dimensionless form by the equation:

Jan 1, 1965

By T. A. Wright

THE SAMPLING of waste materials containing copper, lead and tin has taken on a new significance within recent years, and is of increasing importance, on account of the entry of some of the copper refineries into this field and the tendency towards consolidations among the smelters. In the past, such material was sold on the basis either of a rough or grab sample or of casual inspection of the lot. The two principal sources of this waste are the processes of fabrication and the scrapping of automobile, electrical, plumbing, railroad and other equipment. In both cases much material can be sorted, salvaged and sold by classification and grade to be melted "as is" or with the addition of new or virgin metal. The increasing care in classifying exercised in the large manufacturing plants tends to increase the proportion of this usable scrap; on the contrary, the increasing use of more complex and special non-ferrous alloys tends to make sorting and grading more difficult in turnings, borings, clippings, etc., and consequently is making sampling of more moment. In tin, lead, aluminum, and zinc furnace by-products such as ashes, drosses, skimmings, etc., the trade practice of evaluation has not varied much. For instance, tin drosses, battery lead, and aluminum skimmings are ordinarily sold on what is called' "metallic button" or "metallic recovery" or "metallic yield." Copper and lead waste, however, is being sold more and more on actual copper and lead contents based on sample and chemical analyses. This paper will be devoted chiefly to the sampling of materials suitable only for refining and recovery of one or more of the metals present. The methods described are often based on the fact that but one metal, such as copper, is to be paid for. The loss of volatile constituents in melting does not appreciably affect the final copper result, as the "after-melting" assay can be readily calculated to the "before-melting" basis, but if smelter efficiency continues to increase, so that in time zinc, for instance, may be recovered on a paying basis, the method of sampling dirty brass, for example, will have to be changed also.

Jan 1, 1928

By T. A. Wright

THE SAMPLING of waste materials containing copper, lead and tin has taken on a new significance within recent years, and is of increasing importance, on account of the entry of some of the copper refineries into this field and the tendency towards consolidations among the smelters. In the past, such material was sold on the basis either of a rough or grab sample or of casual inspection of the lot. The two principal sources of this waste are the processes of fabrication and the scrapping of automobile, electrical, plumbing, railroad and other equipment. In both cases much material can be sorted, salvaged and sold by classification and grade to be melted "as is" or with the addition of new or virgin metal. The increasing care in classifying exercised in the large manufacturing plants tends to increase the proportion of this usable scrap; on the contrary, the increasing use of more complex and special non-ferrous alloys tends to make sorting and grading more difficult in turnings, borings, clippings, etc., and consequently is making sampling of more moment. In tin, lead, aluminum, and zinc furnace by-products such as ashes, drosses, skimmings, etc., the trade practice of evaluation has not varied much. For instance, tin drosses, battery lead, and aluminum skimmings are ordinarily sold on what is called "metallic button" or "metallic recovery" or "metallic yield." Copper and lead waste, however, is being sold more and more on actual copper and lead contents based on sample and chemical analyses. This paper will be devoted chiefly to the sampling of materials suitable only for refining and recovery of one or more of the metals present. The methods described are often based on the fact that but one metal, such as copper, is to be paid for. The loss of volatile constituents in melting does not appreciably affect the final copper result, as the "after-melting" assay can be readily calculated to the "before-melting" basis, but if smelter efficiency continues to increase, so that in time zinc, for instance, may be recovered on a paying basis, the method of sampling dirty brass, for example, will have to be changed also.

Jan 1, 1928

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 R. G. Jones, W. L. Kinney, R. E. Schilson, R. S. Wilson, G. A. Clark, H. Suralo

This paper discusses the results of the Fry conventional or cocurrent in situ combustion test, which was conduct-ed in a 3.3-acre inverted five-spot. The depth of the formation was between 880 and 936 ft; the oil had a specific gravity of 28.6° APl and a viscosity of about 40 cp at the reservoir temperature of 65°F. Preceding the combustion test, air injection tests were conducted which, in conjunction with geological studies, were used to evaluate the characteristics of the reservoir. Combustion was initiated on Oct. 13, 1961, with ignition being accomplished by a 40 kw electrical heater. The test phase of the project ended on Oct. 1, 1963. During the test, the average air injection rate was 1,520.-000 scf/D. Throughout the test, production of all fluids— gas, oil, and water—was monitored. Cumulative oil production credited to the project was 100,586 bbl. The cumulative air-oil ratio was 11,500 scf/bbl oil, and the oxygen uti1ization efficiency was 87 per cent. INTRODUCTION The Marathon Oil Co. conducted a successful in situ combustion test, beginning Aug. 22, 1961, at the Fry unit, Crawford County, 111. The purpose of the project was to test the feasibility of cocurrent in situ combustion as a means of oil recovery in the Fry type reservoir. Interest in in situ combulstion as an oil recovery tool has been stimulated mostly by the existence of large reserves of heavy viscous crudes with low expected recovery, usually less than 10 per cent. These are the so-called unrecoverable reserves, and most combustion tests to date have been conducted in this type of reservoir.1-4 In contrast, the Fry combustion test was conducted in a reservoir with a relatively high gravity oil having a relatively low viscosity. This paper discusses the performance of the test. The geology of the reservoir and the field operations are discussed in separate papers.5 TEST SITE The Fry combustion test was carried out in a 3.3-acre inverted five-spot portion of a lenticular body of Robinson sandstone. Net sand was 50 ft thick, porosity averaged 19.7 per cent, oil saturation was 68 per cent of pore volume, and water saturation was 20 per cent of pore volume. The oil in place was estimated at 1,040 bbl/acre-foot, or 171,600 bbl within the 3.3-acre pattern. The water in place was 326 bbl/acre-foot, or 53,800 bbl. The oil has a specific gravity of 28.7° API and a viscosity of 40 cp at the reservoir temperature of 65°F. AIR INJECTION PERFORMANCE Air injection took place in two phases, the phases separated by ignition of the reservoir. In the pre-ignition phase, air injection tests were conducted in the summers of 1960 and 1961. These indicated that the Fry reservoir was confined, and a high return rate of injected air could be expected. This proved to be an outstanding characteristic of the project, as cumulative gas production was 95.3 per cent of the air injected. The difference between the cumulative air injected and the total gas produced can be largely accounted for by the quantity of air stored in the reservoir. An estimated 16 X 10 cf of air remained in the burned-out portion of the reservoir and an indeterminate amount of gas was stored in the unburned but pressurized reservoir. Hence, a complete material balance of gases would account for nearly 100 per cent of the air injected. At times during the test, the daily gas production rate was 98 per cent of the daily air injection rate. Fig. 1 presents the air injection history of the Fry com-

Jan 1, 1966

PRESIDENT AND DIRECTOR SCOTT TURNER WASHINGTON, D. C. PAST PRESIDENTS AND DIRECTORS WILLIAM H. BASSETT WATERBURY, CONN. ROBERT E. TALLY JEROME, ARIZ. TREASURER AND DIRECTOR KARL EILERS NEW YORK, N. Y.

Jan 1, 1932

By E. B. Ekren, F. C. Frischknecht

Recently released results of surveys employing the slingram and turam methods show the applicability of electrornagnetics in mapping new areas containing both oxidized and unoxidized iron in the Lake Superior region.

Jan 10, 1961

By Reaves. M. J.

The title of my talk, "What Happened to the Uranium Boom?" is old news. Certainly it is for this group. All of us that make our living in uranium know that the boom of the last half of the 1970's is over. U.S. production has been exceeding consumption by more than two to one. Mines and mills are closing and yellowcake prices have been dropping for over 20 months. The gloomy outlook for the industry in the near term has been well documented by soothsayers of various descriptions, your daily newspapers, and in the Nuexco Monthly Reports. I'd like to attempt to describe the next upturn in the market (speculate, really) based upon the clues we're seeing now. In order to do that, I'd first like to go over briefly, some of the market factors that contributed to the recent price drop and resultant production cutbacks, and then hypothesize on the way these factors are changing and will change. Market prices are greatly affected (maybe even entirely determined) by buyer perceptions. This is particularly true with uranium, because of the long lead times associated with nuclear plant construction and also with conventional mine/mill development. Before the price rise (say, 1975) utility uranium buyers believed that: 1) U.S. producers would have difficulty expanding to meet U.S. demand. 2) Australian and Canadian production was essential to avoid shortages in the early 1980's. 3) Uranlum prices would continue to rise as demand exceeded supply. 4) Enrichment capacity would become inadequate. It was thought necessary, therefore, to build enriched inventory in the early 1980's for use in the late 1980's. Artificially accelerated expansion of the uranium producer industry was necessary to accommodate anticipated enrichment demand. Current perceptions are largely the opposite. These are the beliefs that were held most of this year and late last year as prices dropped. 1) U.S. production is far in excess of domestic need. Contraction of the U.S. production lndustry is necessary. 2) Canadian and Australian supply is optional and not essential. Producers in those countries are expanding mainly by displacing higher cost production and not because they fill a void, 3) Prices may be essentially stable for some time. 4) Enriched uranium is in excess supply. That is 1981. 1982 is shaping up to look like this: 1) Prices will have bottomed out. (That is not Nuexco's opinion necessarily, by the way, but it is my opinion.) 2) There will still be substantial utility inventories, but fewer spot sales. 3) Canadian and perhaps Australian sellers will have made substantial sales in the U.S. and will be aggressively seeking more. 4) U.S. production will have been dramatically curtailed. U.S. utilities that wish to con- tract long term will have difficulty in finding domestic sellers. Concern will develop about the availability of U.S. production capability. Virtually all long term con- tracts signed will be with non-U.S. sellers. 5) An awareness will begin to develop among U.S. buyers that we are approaching a period of dependence upon foreign uranium (which will be true). The history of the uranium market has been one of dramatic changes and overreaction to those changes. The rapid price rise of a few years ago generated excess U.S. production capacity and the rapid price drop of the last two years will almost certainly result in too little capacity. It will soon be difficult for U.S. buyers to buy domestic material except on the spot market. The question is, "will they care?" The lack of demand, of course, is the underlying reason for the current poor health of the uranium industry. In 1972, 1973 and 1974 collectively, there were 105 nuclear reactors ordered in the U.S. That ordering rate was expected to continue and accelerate throughout this century. In 1975, 1976, 1977, 1978, 1979, and 1980 altogether, there were 56 more reactors cancelled than ordered. The net growth of our only customer since 1974 has been a negative 56. TO put this in perspective, if these 56 reactors were operating now it would more than double present U.S. uranium consumption. Underlying lack of demand is something that is simply not going to change in this decade. Time is going to be required. The NRC indicates that the maximum feasible number of new reactors that can be licensed each year is six. That would increase uranium consumption by only 10% per year. New reactors, if ordered tomorrow, would not generate new uranium demand until after 1990. Even so, United States' consumption of uranium will rise from the 1980 level of 18 million pounds per year, to

Jan 1, 1982

By Mohamed Mortada

A practical analytical method is developed in this paper which provides the practicing reservoir engineer with a handy method for analyzing oilfield interference problems. The procedure employed entails the principle of superposition of individual eflects. A set of charts has been developed and can be used to evaluate the individual effects. The charts represent non-steady state pressure distribution in an extensive aquifer due to a constant rate of production from an oilfield which can be approximated by circular geometry; they are constructed from solutions to the diffusivity equation considering a circular sink as distinguished from a point sink. The solutions are obtained partially from mathenlatical considerations and partially from analog and digital computations. By virtue of the method of images, the charts can be used also to treat the case of production near a fault. In addition, provisions are made for treating oil fields, which are produced by partial water-drive. Treating an actual field case is deferred to a subyequent writing; however, illustrative example is presented to demonstrate the method of application. The pressure distribution in linear and limited radial aquifers is currently under study. INTRODUCTION With the increasing difficulty of discovering new oil reserves, attention is necessarily focused on the efficient development and production of existing reservoirs. Efficient production depends on the availability of reliable means for predicting the pressure-production behavior of oil fields. The prediction is usually performed by analytical methods or computers. Analytical methods are often limited to systems which can be approximated by simple geometry. However, analytical methods have the distinct advantage of being readily performed without special equipment. Analog and digital computers lend themselves to a variety of problems, but are not always locally available and consequently their use is limited. One particular situation in which analytical techniques are needed involves studies of multiple, water-drive oil fields sharing a common aquifer. Such oil fields are in hydrodynamic communication. Therefore, production from any of the oil fields is accompanied by a pressure decline which is transmitted through the aquifer to the other oil fields and manifested as pressure interference. The rate of propagation of the pressure decline is such that the pressure may be significantly reduced many miles away from a producing pool. An example of pressure interference is found in the Woodbine formation in East Texas. There. a dozen or more pools, including several of major size, draw on the Woodbine formation for water drive. The pressure in the water-bearing portion of the formation has been significantly reduced over an area of several thousand square miles. This reduction of pressure has been such that when the Hawkins pool was discovered in 1940, the pressure in it had already been reduced 280 psi below the initial value in the aquifer. This resulted from prior production from other Woodbine sand pools, including, in particular, the East Texas field some 20 miles to the east of Hawkins.' The above example indicates that the interference effect can be significant and should be taken into con-

Jan 1, 1956

By E. C. Barfield, D. G. McCarty

Two-dimensional analyses offer considerable promise in providing the basic information required to effect more precise control of petroleum reservoir performance. This paper describes a method for conducting some engineering analyses of this type using a high-qreed digital computer. The general approach is to (I) develop a representative numerical model of the reservoir and (2) employ a suitable numerical technique to solve the basic equation of flow and to develop the required engineering information for the particular case represented by the model. This technique has been used to calculate pattern performance in connection with several field projects involving water injection into oil reservoirs. This type of analysis involves sequentially (I) calculating the pres-' sure distribution in the reservoir and (2) tracking the progress of the interface between the displaced and displacing fluids in a step-wise manner to provide a depletion history of the operation. The particular analysis presented in this discussion is subject to the restriction that the mobility of the displaced and displacing fluids be equal and assumes that the fluids are incompressible and that gravity and capillary pressure do not affect the shape of the flood pattern. Complete two-dimensional .flexibility is maintained with regard to definition of reservoir rock and fluid characteristics, placement of physical restrains and boundary conditions, investigation of flow characteristics in the reservoir, and movement of the displaced and displacing fluid interface. The results of these studies indicate that the highspeed digital computer is well suited for conducting reservoir performance studies in two-space dimensions and that dependable numerical techniques are available for making such analyses. INTRODUCTION One of the problems facing petroleum engineers is that of providing more precise engineering control over reservoir operations at all stages during the depletion cycle. The most direct approach to this problem is to simulate the reservoir with some type of physical or mathematical model and use the information developed from the behavior of the prototype to predict the performance of the actual reservoir. This principle is, of course, not new, and a variety of simulation techniques have been developed to provide information on the behavior of oil and gas reservoirs. One straightforward refinement of present reservoir analysis techniques is the progress from one-dimensional reservoir models to those where the reservoir can be represented in two- and three-space dimensions. Multidimensional reservoir analyses are desired in order to show not only what is happening in the reservoir but in addition to show where in the reservoir the various phenomena of interest are occurring. Thus far, two-dimensional analyses have been confined predominantly to potentiometric and electrolytic model studies. However, when large numbers of wells are involved and where large-scale models are required, such problems become very tedious and instrumentation problems become acute." It is possible through use of numerical methods and general purpose digital computers to avoid many of the instrumentation difficulties and to relax some of the restrictions of previous techniques. The purpose of this paper is to discuss some recent experiences with the use of high-speed digital computers for predicting pattern performance in fluid injection operations and to describe the numerical procedures which have been used for making such analyses. THE NUMERICAL MODEL The problem of representing the reservoir with an appropriate numerical model is composed of at least two important considerations. The first requires that an adequate description of the reservoir mechanism be formulated in the form of the basic differential equation describing the process. The second consideration is definition of the physical characteristics of the reservoir. The latter requires that representative basic data be obtained, examined, and interpreted to provide sufficient detailed definition of the pertinent physical properties throughout the system. The Differential Equation One of the basic assumptions made for the purpose of performing the two-dimensional studies being dis-

By W. B. Braden

This paper presents a suitable method for predicting gas-free oil viscosities at temperatures up to 500F knowing only the API gravity of the oil at 60F and the viscosity of the oil measured at any relatively low temperature. The API pravity and the one viscosity value are used as parameters to determine the slope of a straight line on the ASTM slanaord viscosity-temperature chart. Then, knowing the slope of the line and one point on the line, the vrscosities at higher temperatures can be determined. The line slope correlations were developed at I00 and 210F since viscosity data are frequently measured at these temperatures. A procedure is given for predicting line slopes from measurements at other tetnperatures. A nomogram is furnished for solving the relationship. The correlation has been evaluated at temperatures up to 5OOF for oils varyzng in gravity from 10 to 33 " API. The correiution is applicable only to Newtonian fluids. Comparison at 500F of true viscosities and those predicted from values at 100F shows an average deviation of 3.0 per cent (maximum deviation of 6.0 per cent). Predictions from the values at 21 0F for the same oils how an average deviation of 1.5 per cent (maximum deviation of 3.4 per cent). INTRODUCTION Correlations have been developed by Beal' and by Chew and Connally' for predicting viscosities of gas-saturated oils at reservoir conditions. Each of these correlations requires a knowledge of the solution gas-oil ratio and the viscosity of the gas-free oil at the reservoir temperature. For temperatures below 350F, measurements of the gas-free oil viscosities can be made easily using commercially available equipment. In thermal recovery processes, however, reservoir temperatures well in excess of 350F are encountered. Viscosity measurements at such conditions are more difficult and time consuming and require modification of existing equipment or the construction of new equipment. Measurements are further complicated by the difficulty of handling highly viscous oils associated with thermal recovery processes. Therefore, it is desirable to have a correlation which allows accurate prediction of viscosities at high temperatures. A commonly used technique for predicting viscosities at high temperatures is to measure the viscosities at two lower temperatures, plot the values on ASTM standard viscosity-temperature charts and extrapolate to the temperatures desired. If either of the values is slightly in error, the extrapolated value can be significantly in error. To justify an extrapolation, three points are actually necessary. This procedure can consume much time, particularly with heavy oils. Considering the cost of viscosity measurements, it would be desirable to eliminate the need for direct measurements by having correlations which would allow viscosity predictions from other physical or chemical properties. Beal1 investigated the possibility of correlating viscosity with oil gravity at temperatures from 100 to 220F. While showing that a general relationship exists, he also found significant deviations. It is possible that correlations will be developed based on oil composition as more information becomes available. While not eliminating the need for viscosity rneasurements, the method presented herein requires that only one viscosity measurement be made. The API gravity must also be known. The theory is based on the fact that the viscosity of paraffins (high gravity) changes less with temperature than does the viscosity of naph-thenes or aromatics (low gravity). The gravity. therefore, is used as a parameter to determine the slope of a straight line on the ASTM standard viscosity-temperature charts. The correlation is applicable only to Newtonian oils, and deviations due to thermal decomposition and nonhomo-geneity cannot be predicted. Oils containing additives have not been evaluated. PROCEDURE Fifteen oils were used in developing the correlation; eight were crudes and seven were processed oils. Oil gravities varied from 9.9" API (naphthene base) to 32.7' API (paraffin base). The temperature range studied was 81 to 516F. Each oil used had a minimum of three viscosity measurements and each plotted essentially as a straight line on the ASTM charts. In all, 91 viscosity measurements were used in the correlation. Saybolt, rolling ball and capillary tube viscometers were used for the measurements. Viscosity data for Samples 1, 2, 4, 7, 10, 11 and 14 were obtained in Texaco, Inc. laboratories. The data for Samples 3, 5, 6, 8, 9, 12 and 15 were from Fortsch and Wilson,3 and data for Sample 13 were from Dean and Lane.' All data points used in the correlation are plotted in Fig. 1. It is seen that some of the viscosity values deviated slightly from the straight-line plots at the higher temperatures. Properties of the oils after exposure to the

Jan 1, 1967

By H. Kenworthy, R. B. Fisher, R. G. Knicherbocker, M. M. Fine

The progress made to date in the mineral dressing of complex Arkansas titanium ores is reported in this paper. Concentrates of rutile, a dioxide of titanium, were produced by treating a submarginal ore from the Magnet Cove Rutile Co., Inc., Magnet, Ark. The rutile recovery at present is 45 to 50 pct of the total TiO2, with the possibility of increased recovery with additional research. The work reported herein is part of a general study which will later include results of investigation of other titanium ore bodies in the Magnet, Ark., area. The fragile character of the rutile minerals, the softness of the gangue, the occurrence of pyrite and leucoxene, and the considerable proportion of extremely small size rutile in the presence of montmorillonite- and illite-type clays in the Magnet Cove open-pit mine are the important factors in the mineral dressing of this submarginal rutile ore. History The occurrence of titanium minerals in the Magnet Cove area of Arkansas was recognized as early as 1890, but it was not until about 1912 that any appreciable prospecting for the minerals was undertaken. At that time drilling was begun, a shaft was sunk, and several drifts were driven, but beneficiation to recover the titanium minerals was not attempted. The only successful mining and milling operation of the Magnet Cove rutile deposit was begun in 1932 by the Titanium Corp. of America and continued until 1942. The ore was washed by means of a rotary scrubber and then deslimed in a drag classifier. The discharge was ground in a rod mill, classified, and tabled to recover a rougher rutile concentrate, which was screen-sized and retabled on cleaner tables. The cleaner concentrates were given a reducing roast, screen-sized, and magnetically separated to produce a finished rutile concentrate. Most of the rutile produced during this period was sold abroad. In 1942, the Titanium Alloy Corp. of Arkansas (a subsidiary of the Titanium Alloy Manufacturing Co. of New York) purchased the property and rebuilt the mill. Subsequently, the plant and property were acquired by the Magnet Cove Rutile Co., Inc., of Little Rock, Ark., the present owners. Very little titanium has been produced since 1942. Although the Titanium Corp. activities yielded enough returns to allow continued operation for approximately 10 years, certain factors must be recognized. These are: (1) production of rutile in that period was during a low in the economic cycle which permitted low-cost operation on a small scale, and (2) a considerable portion of the production was above the water level and no drainage problems existed. Prior to this paper there has been no published report of any mineral-dressing investigation of the lower levels of the ore body. Reference is made in another paper1 to an earlier investigation of Magnet Cove rutile by the Rolla laboratory, in which it is stated that recoveries of 12 to 17 pct of the rutile were obtained. The present investigation was undertaken to improve the known milling processes and to provide adequate metallurgical information about the ore treatment. Titanium Technology The titanium mineral of primary interest in the present investigation was the titanium dioxide, rutile. Rutile is one of the industrial minerals whose annual consumption is relatively small but strategically important. The domestic production of rutile was 7100 tons in 1948. The imports of rutile in the same year were approximately 8000 tons.2 A major use of rutile is in the production of welding-rod coatings, for which a product containing a minimum of 92 pct titanic oxide is desired. Other constituents, such as lime, silica, and sulphur, must be held to a minimum, but hard-and-fast specifications for these elements cannot be drawn. It is necessary to incorporate the rutile in a welding-rod coating, make a sufficient number of test welds, and then determine the tensile strength of the weld metal in the as-welded and stress-relieved conditions. Such a test gives

Jan 1, 1950

By D. C. Porterfield

-4s a result of world economic conditions brought about by the European war and the consequent loss of European markets for Venezuelan crude, production in Venezuela decreased from 205,433,000 bbl. in 1939 to 186,134,000 bbl. in 1940, or 9.4 per cent. This decline interrupted a steady annual increase in production from the country, which had been continuous since 1932. The Maracaibo Lake Basin in western Venezuela accounted for 135,738,000 bbl. during 1940, or 73 per cent of the total, as against eastern Venezuela's production of 50,396,000 bbl., or 27 per cent of the total for the country. Corresponding figures for 1939 were 167,688,000 bbl., or 82 per cent of the total from the Lake Basin, and 37,744,000 bbl., or 18 per cent from the east. These comparisons indicate the increasing importance of the newer developments in eastern Venezuela, but it is unlikely that production from the east will ever exceed that from the west. In all, 429 new wells were completed in Venezuela during 1940 as compared to 438 in 1939. Of the 1940 completions, 411 were in proved areas and 18 were wildcats; 389 (95 per cent) of the exploitation wells drilled were producers, I was a gas well and 21 were dry holes, while 6 (33 per cent) of the wildcats drilled were producers and 12 (67 per cent) were dry; 263 of the exploitation wells and 4 of the wildcats were in the Maracaibo Lake Basin and 148 exploitation wells and 14 wildcats were in the east, mostly in the State of Anzoategui. Exploration of the light-oil areas in the Tia Juana and Lagunillas fields was con- tinued during the year with favorable results. Along the lake shore, drilling was confined principally to fill-in wells in the La Kosa, Tia Juana, Laguni!las and Bachaquero fields, although some important semi-exploratory drilling was done in the Pueblo Viejo area between Lagunillas and Bachaquero fields. The only other developments of particular interest in the west were the successful completion of a step-out well lying to the south of the former southern limit of Mene Grande field, which adds considerable proved acreage to that field; and the failure of two wildcats that were drilled near the Colombian border to determine whether the productive sands of the Petrolea field in the Barco Concession, Colombia, extend into Venezuelan territory. In the east no new fields were discovered during the year, although five wildcats were completed as producers. Three of these, Guario No. I, Jusepin-56 and LM-I (Leona), discovered important extensions to previously proved areas and the remaining two, Cantos-I and SPN-I (Socororo), were subsequently proved to have tapped productive sands of small extent and operations in these areas have been suspended. The greatest activity in the east was concentrated in the Oficina field, where 105 new wells were completed during the year and production was increased from 22,540 bbl. per day during January 1940 to 57,627 bbl. per day during December 1940. Important development work was also done in the Jusepin. San Joaquin and El Koble fields.

Jan 1, 1941