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By J. B. Agan, R. J. Fernandes

This paper utilizes the layered-system approach, modified to include areal sweep efficiency, to determine the miscible-slug size required and to predict the perfort7zance of a miscible-slug process in a highly stratified reservoir having a permeability variation of 0.76. The slug size in each layer was determined from theoretical calculations and laboratory data which showed that, to maintain miscibility in the reservoir, the slug size had to be 8.2 per cent of the floodable hydrocarbon pore volume. Economic considerations, however, such as the value of the miscible product injected, the cost of injection and the cost of reprocessing the miscible product, limited the amount of miscible product which could be injected into the lower-permeability layers. This resulted in subjecting only 60 per cent of the reservoir to a slug size sufficient to maintain miscibility. Utilizing the relationship of producing gas-oil ratio and areal sweep efficiency as a function of pore volume injected (as obtained from data published by Dyes, Caudle and Erickson2), the theoretical performance was determined. This prediction is compared with actual performance to date. Actual performance reflects an increasing percentage of tniscible product in the produced fluid to a particular level, which remains static for a short period and then increases again to a higher level. This performance suggests that the reservoir has performed as a layered system. It is concluded that the layered-system approach can be used to predict performance in a highly stratified reservoir and that economic consideration is a limiting factor in determining the amount of the reservoir which can be miscibly swept. INTRODUCTION The Paloma zone in the Paloma oil field, Kern County, Calif., is comprised of several sand members separated by siltstone, shale and/or cherty sections. Rapid facies changes within the zone indicate that the sediments were deposited in a "near shore" environment. As a result, the Paloma sands have a high permeability variation, and the Paloma zone is comprised of several sand reservoirs. Since one of the sand reservoirs containing crude oil was not receiving the benefits of gas injection, consideration was given to recompleting certain wells to isolate the sand in order to perform a miscible-phase injection project and, thereby, to increase its ultimate oil recovery. Before proceeding with the project, a review of the literature was made to determine the miscible-slug size that would be required to maintain miscibility throughout the displacement process. Although the review showed that considerable information was available for homogeneous systems, insufficient information was available to determine slug-size requirements and to predict performances for a highly stratified reservoir. This paper has been prepared to describe the method used to determine the miscible-slug-size requirement and to predict the performance of the miscible-phase injection project initiated in the Paloma oil field. Although the Paloma project has only been in operation since Aug., 1958, sufficient production history has been obtained so that a comparison can be made with the predicted performance. DESCRIPTION OF RESERVOIR The reservoir in which the miscible-phase project was initiated in the Paloma field is shown on Figs. 1 and 2. Reservoir properties are as follows: average sand thickness, 43 ft; porosity, 19.1 per cent; water saturation, 47.2 per cent: oil viscosity, 0.328 cp; reservoir temperature, 250°F; reservoir pressure, 3,500 psi: gas saturation, 21.2 per cent at time of miscible product injection; and total net hydrocarbon pore volume, 19,993,000 reservoir bbl. LIMITATIONS The method described herein utilizes a layer-system approach, where injection into and production from each layer is assumed to be proportional to the layer's fractional capacity. The effects of increased fluid mobility on injection and production rates, in layers which have had breakthrough, are not reflected in this method. There has been considerable controversy over the slug size necessary to maintain miscibility throughout the displacement process. In this method, the slug-size

By T. M. Chance

THE term "low-sulfur coal," as used in this discussion, is limited to coals containing less, or very little more, than 1 per cent. sulfur. For certain purposes it might be advantageous to include coals that contain as much as 1.25 per cent. sulfur, because such coals have been considered as available for making metallurgic coke of fair grade; but the same reasoning might apply to coals containing as much as 1 ½ per cent. sulfur, if facilities exist for utilizing such coal by admixture with coal containing less sulfur. In Pennsylvania, it is not possible to define the exact geographic limits of the areas in which coals relatively low in sulfur exist, because variations in the percentage of sulfur occur irregularly and often abruptly. It is not uncommon to find areas, more or less circumscribed in extent, in which the coal is relatively high in sulfur although all the surrounding territory contains low-sulfur coal; and, similarly, small areas of low sulfur coal exist in districts where the coal is normally high in sulfur. These generalizations apply, With few exceptions, to the whole area underlaid with bituminous coal in the State of Pennsylvania, and also to each of the individual beds of coal in this state. Pennsylvania is poorly supplied with coals of the low-sulfur class. We find, however, as an offset to this condition, very large areas in which coal ranging from 1 to 2 ½ per cent. sulfur exists in beds of good workable thickness. This coal, by washing, can be reduced in sulfur low enough to make coke of a high grade. While a considerable tonnage of workable low-sulfur coal remains in the Pennsylvania bituminous dis-tricts, it has been necessary to turn to the areas of higher-sulfur coal for the supply of metallurgical coke. This utilization of the higher sulfur areas has been made possible either by washing or by selective mining. Washing.-Fine crushing of the entire feed is not generally necessary to the successful washing of Pennsylvania coals. This is due to the fact that the pyrite is rarely finely and uniformly disseminated throughout

Jan 8, 1919

By M. D. Cooper

FOr the purpose of obtaining some first-hand data in regard to the shooting clown of coal in bituminous 'nines, it was the writer's good fortune to be employed as a shot-firer for almost one year. In all, 6,020 shots were fired by him during this period. All of the work was clone in what is known as the South Main section of the No. 2 Mine of the Ellsworth Collieries Co., Ellsworth, Pa., a subsidiary of the Lackawanna Steel Co. Position of Shot-firing in the Cycle of Operations The established practice of the Ellsworth Collieries Co. calls first for the undercutting of the coal by electric chain machines across the face of the entry or room. This is followed by replacing any posts removed by the machine-runners, or the setting of new posts or timber, as may be required. After this has been done the machine cuttings are loaded into cars. Then the coal is spragged, and a shot hole drilled to the depth of the undercut. Next in order, the shot-firer loads the hole and fires the charge. The working place is then cleaned up, timbered if necessary, the sides and face squared up, and loose material taken down. The face is again ready to be undercut.

Jan 1, 1917

By H. Maleki

Gob pressure measurements were made in a Western U. S. coal mine as part of a long-term program to evaluate cave progress and to determine the influence of geological discontinuities on caving conditions, load transfer, and resulting instabilities. Gloetzl cells were selected for the measurements due to their simple, robust construction and a history of being able to monitor pressures in a broken medium. A methodology was developed for the successful installation and protection of the cells and hydraulic lines in the gob as the face retreated. The measurements indicated a cave progress controlled by the frequency of major faults. The pressure-mining progress profile was compared to those observed in other parts of the world. It was concluded that the significant differences in profiles was caused by the thick-bedded strata, the existence of high lateral stresses, and the spacing between faults. Recommendations are given for future applications of Gloetzl cells for gob pressure measurements.

Jan 1, 1984

By W. M. Rust, W. D. Mounce

THE almost universal acceptance of electrical logging by the petroleum industry calls for a critical examination of the physical bases of the common methods. This is particularly needed for the natural potential log. The conventional explanations are based on the phenomena of electrofiltration and electro-osmosis. However, experimental data show that they fail to give a basis that is quantitatively sound. Moreover, they lead to interpretations of details of electrical logs that are erroneous. It was found experimentally that when a plug of shale is placed in a chain of dissimilar electrolytes, a current flow results. Experiments on oil-well cores and fluids similar to those existing in wells show that potentials are set up which are in reasonable agreement with those encountered in electrical logging. Doubt- less other sources of potential are important but this explanation not only accounts for much of the potential but also clarifies some fairly familiar examples of misinterpretations.

Jan 1, 1944

By Hallan Marsh

THE subject of this paper is apt to bring to mind wells ranging from 6000 to over 8000 ft. in depth. However, it is uncommon to pump wells at depths greater than about 5000 ft. Fig. 1 shows the number of wells being pumped at various depths by one company in Southern California. FIG. 1.-NUMBER OF WELLS BEING PUMPED BY ONE COMPANY FROM VARIOUS DEPTHS IN SOUTHERN CALIFORNIA. A few companies have a very few wells pumping at depths greater than this. This paper will deal with wells between 3000 and 5500 ft. in depth. Most California oils at these depths are between 25° and 35 gravity. The subject is so broad that it will be necessary to omit many interesting phases, and to treat others very briefly. Power, power transmission equipment, power efficiency, counterbalancing, sucker rods, pumps and volumetric efficiency will be discussed.

Jan 1, 1928

By Alfred Brooks

THE only oil produced in Alaska in 1923 was obtained from a dozen small wells, one of which was drilled during the year on the single patented tract of petroleum land in Alaska, in the Katalla field. These wells are owned by the Chilkat Oil Co., which finds a ready local market for its product in the form of gasoline produced in its own refinery. The search for oil has been continued, but except in the Cold Bay field there has been no drilling in new fields during the year. Drilling was in progress during 1923 at Pearl Dome, 18 miles from the coast. Here the Associated Oil Co. sank two wells, about 500 and 950 ft. deep, but suspended drilling in June. The Standard Oil Co., drilling on the same structure, reached a depth of 300 ft. by August and is reported to have reached about 700 ft. by November. The company began the, installation of a second drill in August. George C. Martin, who hastily examined the Chignik region, south of the Cold Bay field, reports that what is known of the geology near Chignik is not favorable to the presence of petroleum. Kirtley Mather, who made a geologic survey of the northern part of the Alaska Peninsula, reports that some of the structures and the formations are favorable to the presence of oil. A small seepage has long been known in the region near the mouth of Douglas River, which flows into Cook Inlet. Sidney Paige last summer made an examination .of the oil seepages which have long been known near Cape Simpson, 50 miles southeast of Point Barrow, the northernmost point of Alaska. He reports that there are two very large seepages emanating from small ridges about a mile apart and several miles from the coast. These are marked by flowing petroleum, and cover many acres. There is a very large accumulation of petroleum residue at these seepages. The surface exposures consist of clay shales with hard thin partings of calcareous shale which lie nearly horizontal, and are probably, of Jurassic age. Mr. Paige and his two sub-parties explored a large area inland from the Arctic coast between Cape Beaufort on the south and Point Barrow and Cape Simpson on the north. He himself ascended the Meade River for 150 miles. These surveys indicate a wide distribution of what is believed to be the formation from which the Cape Simpson seepages emerge, which is probably of Jurassic age. These rocks near the north Arctic coast are little disturbed, but are increasingly folded to the south, toward the mountains. No other seepages have been found, but what is known of the geology is not unfavorable to an oil field. This entire region lies in Naval Petroleum Reserve No. 4, and it was examined by the Geological Survey at the request and expense of the Department of the Navy.

Jan 3, 1924

By H. R. Aldrich

THIS paper presents some of the results obtained during the field season of 1919 while mapping, in detail, the stratigraphy of the Gogebic Range in Wisconsin. The detailed stratigraphic section for the range was first published, in 1919, by W. 0. Hotchkiss,1 State Geologist of Wisconsin. The idea of the continuity of the definite succession thus established was the result of underground work in the productive part of .the range in Michigan and Wisconsin, where most of the required data also were obtained. The bulk of the range in Wisconsin is heavily covered by drift; in fact, there is but one satisfactorily exposed section across the entire formation; few partial sections, and only scanty outcrops of any size. Evidently mapping of the detailed members of the formation could only be established at a few points; and if from these small areas the unexposed portions were to be mapped by projection, the only apparent method for projection was straight-line interpolation modified or supported by data from the scanty outcrops and from test workings. It was found that by tracing a magnetic line, the position of which in the formation may be determined from test pits and outcrops, the projection of that member through the drift-covered areas can be accomplished. The magnetic line serves as a datum horizon within the formation to which reference may be made in correlating outcrops and ledge matter thrown from test workings. The foot wall is easily located also, and from the two datum horizons thus available and the known proportional thickness of the several members in the type sections, outcrops and artificially exposed ledges can be correlated by lithological characteristics. As a result, the tracing-of magnetic lines became the basis of our work on the stratigraphy and we were able to carry the mapping of detailed members throughout the length of the range. It was found that the magnetic horizon at the base of the Tyler slate was most easily followed

Jan 8, 1920

By Howland Bancroft

This article is not presented as a treatise on tin mines and mining in Bolivia. It deals primarily with the tin situation, and but fragmentary information is given regarding individual properties, generalizations being necessary in so short an article. Data on general subjects related to tin mining in Bolivia are necessarily abbreviated and very incomplete. It is believed that the references to be found in this article will help those interested to a more thorough under-' standing of the general conditions extant in Bolivia. Bolivia produces from one-fifth to one-fourth of the world's supply of tin. The United States consumes about one-half of the world's supply and produces practically none. Tin ore is not reduced in the United States. These facts are not generally appreciated by American mining men. Many conflicting data have been published regarding tin in Bolivia. The Transactions of the Institute contain practically no mention of this subject.1 I have made a study of mines and mining conditions in the west coast republics of South America and have been particularly impressed by the possibilities of the Bolivian field.2 In consequence the thought seems justified that the present meeting would, present a fitting occasion to bring the tin situation in Bolivia to the attention of American mining men.

Jan 9, 1913

By M. Lonoff

Byproducts are more important to the copper mining companies than to the copper market. Copper ores frequently contain gold, silver, molybdenum, lead, zinc, and cobalt. With the increase in the prices of these metals copper mining has become more profitable. If byproduct prices remain high, additional firms will be attracted to the copper industry; the increased supply of copper will reduce the long-run copper price. However, this is unlikely to happen because the markets for the copper byproducts, especially molybdenum and cobalt, are small. Increased recovery from copper and other sources will depress the prices of these byproducts before the copper price is significantly affected. Should byproduct prices remain high, the copper market will both settle at a lower long-run price and be more unstable in the short run. Since changes in the copper price do not affect the entire earnings of a multi-metal mine, the copper price must fall further before such mines reduce output in the short run. Higher byproduct revenues will make copper supply less responsive to copper prices; shifts in copper demand will result in greater copper price fluctuations in the short run than they did before.

Jan 1, 1984

By Clarence F. Zeuch

Mr. Shaw's work showed the dodecyl mercaptan as a very good collector compared with other collectors on Cu-Mo ores, Mo ores, and for Au and Au-Ag ores plus Pt ores. However, as one who has had extensive experience on Cu-Mo ores, the work is not complete in making only a rougher concentrate with a collector; the work must be carried on in making a Cu-Mo separation. Did Mr. Shaw do any of this work? Before trying the dodecyl mercaptan as a Cu-Mo collector for the Cu-Mo ore it would be well to have any new work conducted knowing how the reagent acts on the Mo. Will it allow a good separation? The use of the collector at Palabora was also mentioned. From some earlier literature I thought that the reagent has been used as an oxide Cu collector after the sulfide mineral was floated out. I thought the pH at this point was about 1.5-3.0. I would like to have this point clarified.

Jan 1, 1982

By Charles H. Jacoby

Solution-mined salt cavities are being used for storage of liquid petroleum gas, natural gas, and other hydrocarbons; waste disposal or storage; storage of radioactive wastes; and as a surge vessel for air compressed by an electric utility during off-peak hours. Examples of each use are given. Other contemplated uses of salt cavities are noted.

Jan 1, 1973

By A. C. Wallace

THE development of the natural resources of any district of any magnitude, inevitably gives rise to many problems off title, usually due to the greatly enhanced value of the land. The development of the mining industry in the Quapaw Agency has been no exception to this general rule. Our problems, how-ever, have not been many or particularly serious. The Quapaws were allotted and patents issued by the United States Government in 1895. These patents contained a restriction against alienation for a pe-riod of twenty-five years. The effect of the restric-tion was to prevent the Indian from selling, leasing, or in any way encumbering his land. The Govern-ment, in a paternalistic spirit, sought to teach the Indian thrift and industry and to insure him a place of residence. This is evidenced by the first Leasing Act passed by Congress, which permitted only incom-petents and those physically disabled to lease their land for either agricultural or mining purposes. The able-bodied Indian was denied the right to lease. It soon became apparent to the Government, how-ever, that this was a mistaken policy, and in 1897 a General Leasing Act was passed by Congress and it was under this act that the mining industry in the Quapaw Agency was developed. The act, reads as follows: "That the allottees of land within the limits of the Qua- paw Agency, Indian Territory, are hereby authorized to lease their lands, or any part thereof, for a term not ex-ceeding three years, for farming or grazing purposes, or ten years for mining or business purposes. And said al-lottees and their lessees and tenants shall have the right to employ such assistants, laborers, and help from time to time as they may deem necessary: Provided, That when-ever it shall be made to appear to the Secretary of the Interior that, by reason of age or disability, any such allottee cannot improve or manage his allotment properly and with benefit to himself, the same may be leased, in the discretion of the Secretary, upon such terms and conditions as shall be prescribed by him. All acts and parts of acts inconsistent with this are hereby repealed." It was the interpretation of this Act that gave rise to our first serious problems. It will be noted that the Act says that "allottees of land" within the limits of the Quapaw Agency are authorized to lease their land. Thus, the first question was presented by the use of the term "allottee," and the question was as to whether or not Congress intended to limit the Quapaw Indian to the leasing of his own allotment or did Congress mean that the term "allottee" was synonym-ous with "Indian" and intend to give the Indian a right to lease both his allotment and his inherited land and was an Indian without an allotment an "allottee" even though he was a member of the Qua-paw tribe and the owner of the Quapaw land by in-heritance, and not being an allottee, could he lease his inherited Quapaw land under the authority granted in this Act?

Jan 5, 1928

By Lewis T. Wright

IT is commonly believed by metallurgists that in copper-smelting, the copper in the slags, which is irreducible by continued smelting, is retained in the form of "prills" of matte. I have frequently held well-settled slag in a molten condition for a long period without being able thereby to reduce the copper-content. The slag acted as though it contained a minimum of dissolved or combined copper that could not be settled out by gravity. I have used reagents, but without satisfying myself in what form this copper existed. The same slags, by fine grinding and elutriation, could not be separated into portions containing more or less copper than the average content. By treating copper-slags in an electric furnace an impure button of copper. was produced, but the high temperature and the strong reducing-action of the furnace were influences that suggest an explanation of a result not obtainable with ordinary smelting-temperatures. If all the copper in the slag were in the form of copper-matte, and not existing as a dissolved compound with some of the elements of the slag, then the other metals in the matte, such as gold and silver, should occur in the slag in the same ratio to the copper as to the copper in the accompanying matte. This reasoning led me to study the ratio of metals in the products of smelting, and, apart from the issues discussed in this paper, the research has proved both interesting and illuminative. On the assumption of a similar ratio of metals in matte and slag, if the percentage of copper in the slag accompanying; a matte containing 50 oz. of silver and 1 oz. of gold per ton of copper was 0.3 per cent., or 96 oz. per ton of slag, there should be found 0.15 oz. of silver and 0.003 oz. of gold per ton of slag:; but, in my experience, there is less silver and much

Sep 1, 1909

By C. Willard Hayes

One of the most productive iron-ore districts of the southern Appalachians lies in the vicinity of Cartersville, in northwestern Georgia, where the ore-deposits are so directly related to the stratigraphic and structural features of the region that a description of its geology possesses economic as well as scientific interest. Stratigraphy.—The area shown on the accompanying map, Fig. 1, occupies the southeastern portion of Bartow county, Georgia. It is about equally divided between the older crystalline and metamorphic rocks which occupy the Piedmont plateau and Appalachian mountains on the east, and the Paleozoic formations which occupy the Appalachian valley on the west. The line separating these two groups of formations enters the mapped area near the northeastern corner, and, pursuing a somewhat irregular diagonal course, leaves it, as shown on the map, near the southwestern corner. This line marks

Jan 1, 1901

This issue presents the first of several articles making up the Bump Symposium, which was held at the 1958 Annual Meeting of AIME. Other Symposium papers will appear in the September issue of Mining Engineering. THE term mountain bump describes the sudden rupture of one or more coal pillars under excessive stress. These bursts occur with varying degrees of violence and sometimes include adjacent strata, especially the bottom rock. Many failures do not develop enough violence to be dangerous and are regarded as an aid to coal production, but severe occurrences are accompanied by tons of flying coal, dense clouds of dust, and excessive gas emission. Such bursts sometimes throw heavy machinery several feet. Major factors to be considered in the problem are the nature of the strata above and below the seam and the depth of cover. Bumps are classified as to their nature, extent of damage, and point of occurrence, e. g., face bump, coal bump, high side bump, low side pavement bump, and district bump. The problem is extremely complex, and it cannot be over-emphasized that preventive measures, if they are to be successful, must be based on a thorough study of conditions in the individual mine. In western Canada, for example, the McGillivray mine, operating in a 9-ft seam at 2000 ft, has experienced severe bumps, but there have been no occurrences in the International mine, which operates in the same coal seam at 2400 ft, where the coal averages 17 ft thick. Differences in conditions governing the operation of these two mines are described in one of the following articles (see page 883). Again, most bumps in coal mines take place along pillar extraction lines, but at the Sunnyside mine in Utah they also occur a long way from active workings and sometimes in virgin territory. It is usual, too, for such failures to occur under fairly deep cover. But at Sunnyside, to cite only one instance, there have been disturbances along the main fault zone under less than 500 ft of cover. All too often conditions favorable to bumps are revealed only by actual mining—at Springhill No. 2 mine, drilling in roof and pavement strata disclosed a 60-ft sandstone bed after operations had started— and where extraction has advanced too far for preventive measures to be incorporated in the mining plan, districts have had to be abandoned. But in an era when premium ores are being rapidly depleted in the face of rising demands, abandonment is not easily justified. There must be systematic planning to eliminate coal mine bumps, insofar as this is possible. As in the Gary district of West Virginia (see page 888) much has been accomplished by planned operations based on known factors in bump control. But even this is not enough. Precise instrumentation is needed to indicate where bumps are likely to occur, and in both the U. S. and Canada stress analysis studies are being carried out with this object in view. These pages reveal the progress being made.

Jan 1, 1959

By Joseph C. Buchen

IN principle, production of salt from sea water is a simple operation. Sea water is trapped in ponds, the sun and wind cause evaporation of the water, and what is left is principally salt. Commercial production of solar salt, however, requires a careful consideration of many factors. Obviously, sufficient evaporation must take place throughout the making season to produce an economically adequate crop. Other factors are density of soil, contour of ground, height of ground above sea level, minimum dilution from fresh-water streams, and distance from market. Unfortunately, in the United States the localities of greatest evaporation, allowing for the other factors, are not the most suitable for the manufacture of sea salt by solar evaporation. The south end of San Francisco Bay most

Jan 1, 1937

By Milton E. Wadsworth

Hydrometallurgical processing of ore deposits by solution mining or in situ techniques requires the interfacing of technologies as diverse as hydrology, geology, chemistry, and rubblization. This synthesis represents one of the main challenges to in situ processing due to the inherent complexity and vocabulary of these well-developed technologies, and to the general lack of appreciation for the depth of knowledge and endeavor in each separate field. No better example of the need for such interfacing of technologies exists than that of solution mining. How well these technologies interface depends upon the size of the operation and its financial capability to use the information and technology available. It is inconceivable that any one individual can optimize each potential contribution alone; consequently, some areas are usually neglected or simply are not fully appreciated. When one examines what must be done at a future date to develop and exploit a remote solution mining system, it becomes obvious that each discipline must effectively communicate the needed background information to make the project a synthesized whole.

Jan 12, 1977

By Moshe Sheinkin, Burke O. Trafton

This paper describes the use of a computer in analyzing the expected return on a mining venture. The computer program is designed to incorporate all aspects of a mining project, including the mine, mill, smelter, and refinery. Data input may consist of the operating variables in each phase such as the mining rate, grades, reserves at the mine, and the technical operating characteristics of the mine, mill, smelter, and refinery. Detailed tax computations are shown for a domestic operating company, for a foreign company and for a foreign subsidiary. In addition, the use of the various options that are available such as expense write-offs or deferments to create tax credits during preproduction years are considered, and its effect on the DCF. The program is also constructed to accommodate changes in metal prices, and escalation of capital requirements and operating costs. Output consists of profit and loss statements for entire projects using different methods of depreciation, cash flows, discounted cash flows, net present value and returns on investment. Returns on investment are computed for equity investment, total investment, and total investment less tax credits. Allowances are made for bank and guaranteed loans. Additional financial statements can be made for the following: a) A mine-mill segment with a concentrate selling schedule b) A mine-mill-smelter complex with a smelter product selling schedule c) Profitability of the smelter separately d) Profitability of the refinery separately

Jan 1, 1969

By Simon D. Handelsman, Reg M. M. Rowe

The mechanism of using gold as the basis for a loan was suggested to the treasurer of a mining company operating two gold heap leach mines at a time of high interest rates. Due to the seasonal nature of cash flows from operations, and the relatively low cost of funds this scheme was attractive. The paper describes the agreement with the bank, gives an example of the transactions, and describes other types of gold loans.

Jan 1, 1985