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By J. L. Huitt, IM. L. Slusser, E. E. Glenn, M. L. Slusser

This paper is concerned with: (1) an analysis and interpretation of the filtration characteristics of drilling muds on filter paper, and (2) an interpretation of early stage "filtration" on consolidated synthetic porous media, herein referred to as the "surge loss" period. It is shown that water-loss data can be plotted so as to disclose the existence of a surge period, a non-uni-form cake thickness period, and a constant pressure filtration period. The same periods occur during exposure of consolidated porous media to muds. The data on consolidated porous media indicate that: (1) mud particles bridge pores inside porous media during the surge period, and (2) "filter cake" build-up inside porous media occurs during subsequent filtration. The data also show that the surge loss increases with sample permeability and with pressure differential. INTRODUCTION The phenomenon of mud filtrate invasion into porous sands of a drilling well has been recognized for many years.1,2,3,4 Part of API Code 29 is concerned with the filtration testing of a drilling mud to yield data on this subject. In a number of investigations "plastering properties" of muds were studied,5,6,7,8 "plastering" apparently meaning cake forming properties. In such studies the characteristics (thickness, permeability, and toughness) of the cake and the rate at which the liquid phase of the mud was separated from the solids (filtration rate through the cake, commonly referred to as water loss) were measured or at least considered. From the standpoint of its effect on well productivity, filtrate invasion into "clean" water-wet pay sands (i.e., those containing no clay minerals) may not necessarily be a serious problem. An increase in water saturation in the zone immediately around the wellbore would cause loss of oil permeability. However, in such a system, much of this water may be removed by oil production. If filtration occurs into "dirty" sands (i.e., those containing appreciable clay minerals), clay swelling or other mechanisms may cause losses in oil permeability which cannot be overcome by oil production.'.' The phenomenon of mud particle invasion into the pay sand of a drilling well was considered to be a possible serious factor in the early days of rotary drilling. Opinions varied as to whether drilling fluids "mudded up" and "sealed" oil sands. In 1932 Rubel,9 Gill,10 and Parsons," in separate papers, presented differences of opinion together with some laboratory and field data concerning loss of oil production caused by drilling fluid invasion into pay zones. These papers, and the discussions, furnish a large background on this subject and indicate the very clear thinking of many men at a time when petroleum production technology was in its infancy. Jones and Babson,6 and Silent,' experimentally found that the depth to which mud particles invaded water-saturated sand packs was small (no greater than 1/16 in). Arn-quist12 in 1937 observed loss of water permeability due to invasion of mud particles into water-saturated, consolidated, sandstone samples. Williams and Cannon5 studied the filtra-tion properties of drilling muds and mentioned "sludge" which penetrated a short distance into the water-saturated filtering medium (sand pack). Byck5 concluded that formation permeability had no effect on the plas-

Jan 1, 1958

By H. H. Stoek

A study of Americarf coal-mine practice shows two of its distinctive features to be: A greater number of accidents per thousand employees than in any of the other leading coal-producing countries; a much greater percentage of the coal lost than in any of the other leading coal-producing countries. Although our subject is mainly concerned with the second feature, any consideration of mining methods should include safety, efficiency, and economy or costs. If the argument could be offered that our wasteful mining was necessary on account of safety, and that it is carried out with less loss of life than in other countries, the plea for conservation of coal could not he so strongly urged. But when we are wasteful of both life and property, the subject merits more: consideration than it has received. Some coal operators will doubtless say that the unit of accidents should be the number per million tons produced rather than per thousand employees, for by adopting this unit America probably stands in the lead rather than the lowest among the countries. However, vital statistics are not usually so expressed by other governments, by life and accident insurance companies, or in other industries, and it is merely begging the question and attempting to bolster up a bad condition to adopt a peculiar unit for the statement of our accidents. For many years the statement was made by various agencies, and was unchallenged, that "For every ton of bituminous coal mined in the United States a ton had been lost in the way of pillars left in the mines." This statement was undoubtedly true for many years, and although in the past decade some progress has been made toward obtaining a higher extraction, and in some districts very decided progress, the loss is still great; and, although no exact data can be given, it is probable that for the United States as a whole at least one ton is lost for every two mined.

Jan 1, 1923

By Alfonso Rizo-Patrón, A.M. Gaudin

Previous studies of activation in flotation have directed attention to the action of the activator on the mineral to be floated rather than to the relationship of the activator to the collector. The latter phase of the problem, however, seems to have definite scientific, if not also practical, interest. In the investigation reported in this paper, experiments were carried out, largely with quartz as subject, barium as activator, and oleate as collector. The results obtained indicate that a I: I ratio of collector ion to activator ion gives optimum results, and that a 2:1 ratio almost fails to achieve activation and flotation. Yet, a 2:I ratio would have been expected on stoichiometric grounds, had the coating been a normal salt of the activator ion with the collector ion, since barium is a divalent cation and oleate a monovalent anion. To interpret and rationalize the observations, considerations of the crystal chemistry of quartz are helpful. The point of view to which these considerations lead may be of general applicability to systems involving suspensions of solids in liquids; they confirm that an adsorbed coating is inescapable. Apparatus and Supplies The experimental work consisted in barium-ion abstraction tests, hydrogen-ion and hydroxyl-ion abstraction tests, flotation tests, and determinations of the surface of the crushed quartz. The flotation machine was built according to the design of D. W. McGlashan.* It consists of a drill press in which the bit has been replaced by a stainless-steel impellor surrounding a stainless-steel sta-tor, as in the Fagergren laboratory machine. The air intake is controlled by a valve, and the cell consists of a beaker. The quartz was obtained from vein quartz stored in large chunks. It was first crushed to 20 mesh, then sized on a 28-mesh screen. The 20 to 28-mesh size alone was retained for use. This size was freed of coarse iron by passage through a Ball-Norton magnetic separator, bleached with boiling hydrochloric acid to remove residual abraded iron, washed with distilled water until the washings were thoroughly free of ferrous, ferric, and excess hydrogen ion, and stored in covered Pyrex beakers under water until used. The barium was used as barium chloride, Baker's analyzed C. P. The oleate was used as sodium oleate. It was prepared from sodium hydroxide, Baker's analyzed C. P., and oleic acid purified by R. R. de Arellano3 in the laboratories at the Massachusetts Institute of Technology. The purification procedure was elaborated from the recent $researches of Brown and Shinowara.2 It consisted in: (I) saponification of olive oil with potassium

Jan 1, 1943

By E. C. Babson

In order to explore the possibility of predicting reservoir performance from laboratory data, behavior of a hypothetical low-permeability reservoir has been estimated by applying data and methods currently available in the literature. A method of calculating decline in productivity index is discussed, and recoveries by internal gas drive, external gas drive and water drive are estimated. Introduction During the life of a producing oil property an operator is faced with many perplexing problems. Any attempt to determine proper well spacing, optimum rate of production, or the desirability of pressure maintenance requires the evaluation not only of a host of economic and practical operating factors but also of the future performance of the reservoir. Although in some cases economic or operating con-siderations may be of primary importance in planning a development or production program, the anticipated effect on ultimate recovery is more likely to be the decisive factor. The soundest basis for evaluating reservoir performance is past experience with oil fields, but pertinent data are difficult to obtain or apply under conditions normally encountered in California fields. Many of these fields are characterized by thick sections of alternating sands and shales complicated by faulting and rapidly changing lithologic conditions. Further compli- cations are introduced by haphazard development and production practices resulting from competitive conditions, changing demand for oil, and insufficient knowledge of structural conditions during early development. Even in the rare cases where development has been systematic and adequate, production policy has usually been controlled by economic and competitive factors rather than a desire to obtain information for use in future operations. In other words, comparable reservoirs in which development and production practices have been systematically varied are seldom found. In the light of these conditions, conclusions based on experiences usually lack the certainty required for decisions involving large sums of money. Some other method of attacking these problems is needed to supplement and orient field experience. Progress in laboratory investigations of the flow of oil, gas, and water through sands has been so rapid in recent years that these data may furnish such a supplementary approach in the near future. In order to explore this possibility the author has attempted to predict the behavior of one type of reservoir by applying published data and methods. Basic Data and Assumptions Calculations outlined in this paper are dependent upon a detailed knowledge of the properties of oil, gas, and water present in the reservoir and the portion of the total pore space originally filled by each. It is also necessary to know how the permeability of the sand to oil, gas, and water varies with the saturations of these fluids 20

Jan 1, 1944

By T. W. Guy

DuRing recent years, tremendous strides have been made in the economical use of coal. This has resulted in, and to some extent has been a result of, making the fuel specifications more and more rigid. For this reason, all producers have found it necessary to improve their preparation materially, both as to sizing and the elimination of impurities, either by more effective preparation underground or at the tipple and cleaning plant, or both. This cause and its effect in all producing fields seem likely to continue for several years at least. The splendid inherent qualities of the Pocahontas and New River coals are known all over the world, but their good reputation is only partly due to inherent qualities, and to natural conditions which generally favor loading coal comparatively free from impurities; it is due in large measure to the care and skill used, either with or without the aid of mechanical devices, to ship products consistently low in ash. The first coal from the West Virginia smokeless fields was mined and shipped near Quinnimont, on New River, in 1871, while the first shipments from the Pocahontas field were in 1883. The development of both fields progressed rapidly. At first activities followed the main lines of the Chesapeake & Ohio and Norfolk & Western railroads, and were extended later as branch lines were built from these roads. The Virginian R. R., about 1907, opened up the Winding Gulf territory, which has since become a large producer of smokeless coals from the Pocahontas and the New River measures. Early Cleaning Methods In the early days, the tipples were simple wooden structures, with bar screens for separating the fines from the lump coal. All cleaning was done by the miners at the face, or by pickers in the railroad cars. Gates were provided in the chutes by which the flow of coal could be stopped when necessary while the pickers raked the surface of the coal in the car and picked out the impurities. A large percentage of the fine coal or slack was used for making coke at the mines in beehive ovens. The

Jan 1, 1932

By John Langton

In determining what kind of pourer should be adopted for the works of the Moctezuma Copper Co. at Nacozari, Sonora, Mexico, certain considerations imposed by local conditions had to be taken into account. Water.—During most of the year the water-supply is abundant for all purposes, but it dwindles rapidly when the dry season sets in, reaching a minimum flow which is entirely undergrouad. It was evident, that with the greatest care in keeping down the unavoidable loss of water in milling and smelting, these operations and hence the capacity of the works mould ultimately be limited for about two months of the year by the small watersupply available at the period of minimum flow. Transportation.—The nearest railway terminus was in Arizona, at the international boundary-line; and the price of supplies at that point would be enhanced at Nacozari by the additional cost of a 90-mile wagon-haul. During the rainy season, transport to Nacozari was much impeded, and at times made impossible, by the condition of the roads. Hence, to insure continuous operation at the works, it would be necessary to provide for hauling the year's supplies, including fuel for power and coke for smelting, in less than eleven months. In other words, the average freight delivered daily at the works should be at least 10 per cent. more than the average daily consumption. For moderate quantities of freight, pack-carriage by burros is astonishingly cheap. But it has a capacity-limit which is generally very soon reached. A 200-lb. load, and 10 miles a day, 5 with and 5 without load, is the full capacity of a burro. This means one burro per ton-mile of the round trip; and,

Jan 1, 1904

By R. Floyd Farris

A THOROUGH knowledge of the behavior of cement slurries under elevated tempera-tures and pressures is necessary in order to solve properly the many problems pre-sented in deep-well cementing operations. In the earlier days of the petroleum indus-try the depths of wells were shallow as compared to those of today, and the subsurface temperatures and pressures were not of sufficient magnitude to affect seriously the problem of proper control of cement-slurry properties. Today, however, the search for new reserves has extended drilling to such depths that bottom-hole temperatures of more than 200°F. and bottom-hole pressures of 3000 to 5000 lb. are not uncommon. Moreover, there is every indication that within the next few years wells will be drilled to even greater depths and bottom-hole temperatures and pressures will be correspondingly higher than those with which we are concerned today. It has been realized for some time that the behavior of cement slurries at high temperatures and pressures might be very different from that at atmospheric tempera-ture-pressure conditions, but while the temperature effects have been investigated with a reasonable degree of thoroughness, the pressure effects have received little public attention. While the trend toward deeper drilling may make changes in cementing technique and the choice of cements imperative, it was the purpose of this investigation to consider factors having a bearing on the latter, only secondary consideration being given, for the present, to details of tech-nique and equipment for oil-field use. More specifically, the purpose of this work was to consider the effect of temperature and pressure upon the behavior of cement slurries.

Jan 1, 1940

By John Campbell

An approximate theoretical model is proposed to quantitatively predict freezing ranges Tf and hydrostatic tensions P developed within solidifying binary alloys, allowing for a certain amount of diffusion of solute in the solid during solidification. The maxima in ATf and AP as functions of composition are shorn to occur at smaller solute concentrations than would be expected from the equilibrium diagram, and are found to correspond closely to experimentally observed maxima in microporosity. THE freezing range of simple binary alloys appears to have been little studied, except for certain indirect observations on the defects, particularly microporosity and hot tearing, arising in long freezing range materials. Two theories relating to the freezing range of alloys and its effect upon porosity are reasonably well established, and appear to have been held in isolation from each other: a) From purely equilibrium considerations early researchers expected that an increase in solute content of an alloy should increase the freezing range (defined here as the equilibrium freezing range ?Tf = Tl-Ts where TL and Ts are the liquidus and solidus temperatures, respectively) and thereby increase the width of the pasty zone for a given set of conditions. This in turn should increase the difficulty of feeding the residual liquid through the dendrite mesh to compensate for the contraction on solidification, and consequently tend to increase the observed amount of porosity. From qualitative observations on steels Czikel1 reports an increase in porosity with increasing carbon content up to 0.46 pct C. More careful measurements by Whittenberger and Rhines2 on fourteen different alloy systems showed an approximately linear relation between ?Tf and pct porosity (although unfortunately the precise experimental data is not given). b) Conversely however, other authors3"5 propose that porosity is reduced by the presence of increased amounts of eutectic present at the final solidification temperature. Lees7 and Bochvar6 claim that the hot tearing of alloys is similarly reduced. Scheuer8 has put forward a theory to explain this effect, Fig. 1. The argument is basically that solidification progresses on a plane front through a relatively open dendrite network and is thus (the argument is not developed more explicitly) easier to feed. One would expect effect a) to operate at low solute contents, and b) to be important at higher solute contents, so that at some critical composition a max-

Jan 1, 1970

THAT the march of civilization has synchronized with progress in the art of utilizing minerals is a proposition that needs no proof. It is a truism. Historians conveniently divide the time that the earth has been inhabited into the Stone Age, the Bronze (more accurately the Copper) Age, and the Iron Age. As archeologists are not entirely in accord as to dates, and as a few centuries make no difference whatever to this particular story, it may be approximated that the Age of Copper began about 8000 years B.C. and that it gave place to the Age of Iron about 1000 years B.C. The logic of this succession-stone, copper, iron-lies in the fact that copper first displaced stone, then iron displaced copper as the standard material out of which the utensils, implements, and weapons, the utilitarian articles of antiquity, were made. After the advent of iron, the mining and smelting of copper continued. Copper and bronze found use particularly in objects of artistic and ornamental nature; but the superior qualities of iron for many purposes were recognized. Useful manufactures of those days consisted principally of knives, hammers, chisels, spear-heads, arrow-heads, and battle-axes. First these were made of stone, then of copper and bronze, then of iron-particularly as there was plenty of iron ore, and the metallurgy was comparatively easy of accomplishment. Of course, the periods of transition dragged slowly. Definite as were the three Ages dominated by the mineral substance from which they get their names, ten or fifteen centuries probably elapsed from the time the first iron was smelted in a small charcoal furnace until it became the accepted material from which to shape a battle-axe. Contrast this with the pace of modern progress. In a brief span, half a dozen more or less deserving candidates for the distinction of having their name

Jan 1, 1933

By Chung Wang

CHINA now leads the world in antimony production, having contributed during recent years something over 60 per cent. of the world's production. The history of the antimony industry of China dates back to 1897 when the Tai Shing Co. was formed, under contract with the Hunan. Bureau of Mines, for the smelting of the ore to crude; and in 1908 the Wall Chang Mining & Smelting Co. was formed for the smelting and refining of the ore and crude to regulus. The writer was then asked to take charge of the erection and control of this first plant for regulus production in China and has, since then, been more or less connected with the antimony industry in this country. This paper contains the results of many years' experience in connection with the Wah Chang Mining & Smelting Co., Changsha; the Pao Tai Mining & Smelting Co., Wuchow; the Loong Kee Smelting Works and the To-Cheng Smelting Works, Hankow; as well as information gathered from various other small smelters, scattered in different parts of the Provinces of Hunan, Hupeh, Kwangsi, and Kwangtung. An idea of the growing importance of regulus production in this country can be gleaned from the fact that, within a period of about 8 years, the export of regulus from Hunan alone jumped from 3 tons in 1908 to about 6000 tons in 1915; that a production of about 23,000 tons of regulus per year could easily be effected from all the smelters, as tabulated below, most of which were erected a year or two ago under the stimulus of the war booms, if the price at Hankow were to stay somewhere about $900 (Mexican) per ton, half of what it was at its height, thus enabling the utilization of ores from the hinterlands of the provinces; and even under the present ruling of prices and the closing of the less-favored smelters, the production of regulus should not be less than 12,000 tons per year.

Jan 4, 1918

By Alfonso Rizo-Patrón, A. M. Gaudin

Previous studies of activation in flotation have directed attention to the action of the activator on the mineral to be floated rather than to the relationship of the activator to the collector. The latter phase of the problem, however, seems to have definite scientific, if not also practical, interest. In the investigation reported in this paper, experiments were carried out, largely with quartz as subject, barium as activator, and oleate as collector. The results obtained indicate that a I: I ratio of collector ion to activator ion gives optimum results, and that a 2:1 ratio almost fails to achieve activation and flotation. Yet, a 2:I ratio would have been expected on stoichiometric grounds, had the coating been a normal salt of the activator ion with the collector ion, since barium is a divalent cation and oleate a monovalent anion. To interpret and rationalize the observations, considerations of the crystal chemistry of quartz are helpful. The point of view to which these considerations lead may be of general applicability to systems involving suspensions of solids in liquids; they confirm that an adsorbed coating is inescapable. Apparatus and Supplies The experimental work consisted in barium-ion abstraction tests, hydrogen-ion and hydroxyl-ion abstraction tests, flotation tests, and determinations of the surface of the crushed quartz. The flotation machine was built according to the design of D. W. McGlashan.* It consists of a drill press in which the bit has been replaced by a stainless-steel impellor surrounding a stainless-steel sta-tor, as in the Fagergren laboratory machine. The air intake is controlled by a valve, and the cell consists of a beaker. The quartz was obtained from vein quartz stored in large chunks. It was first crushed to 20 mesh, then sized on a 28-mesh screen. The 20 to 28-mesh size alone was retained for use. This size was freed of coarse iron by passage through a Ball-Norton magnetic separator, bleached with boiling hydrochloric acid to remove residual abraded iron, washed with distilled water until the washings were thoroughly free of ferrous, ferric, and excess hydrogen ion, and stored in covered Pyrex beakers under water until used. The barium was used as barium chloride, Baker's analyzed C. P. The oleate was used as sodium oleate. It was prepared from sodium hydroxide, Baker's analyzed C. P., and oleic acid purified by R. R. de Arellano3 in the laboratories at the Massachusetts Institute of Technology. The purification procedure was elaborated from the recent $researches of Brown and Shinowara.2 It consisted in: (I) saponification of olive oil with potassium

Jan 1, 1943

By Irwin Roman

Numerous results and formulas have been published for analyzing seismic records, but most of them apply only to large-scale phenomena such as are encountered in studying earthquakes. In a few cases,' formulas have been published for some of the simpler structures. In the present paper, an attempt will be made to analyze several types of structures without using methods more advanced than those of a first course in calculus. In tracing a disturbance through a medium, it is almost always possible to base the analysis on Fermat's Principle of Extreme Time, which states that waves of displacement travel between points in such a manner as to make the time of travel an extremum with respect to all neighboring paths. In the simpler cases, comprising most of those used in optics or geophysical prospecting, this time is a minimum and the principle is often referred to as the Principle of Least Time. Within a homogeneous medium, having a uniform speed of transmission of the disturbance in all directions and throughout the medium, the paths are straight and are refracted at the interfaces in accordance with the Snell law of refraction, which states that the ratio of the sine of the angle, made by the ray with the normal to the interface, to the speed of transmission is the same on both sides of the interface. Thus, in any medium composed of homogeneous sections, this same ratio has a constant value at all points. In particular, if all interfaces are horizontal, it is apparent that the angles of incidence are the angles made by the ray with the vertical direction. Furthermore, the incident ray, the refracted ray and the normal to the interface are all in the same plane at each refraction,

Jan 1, 1934

By C. W. Vaupell

THE Huitzuco mines lie in north central Guerrero, Mexico; production has been about 90,000 flasks of quicksilver since 1873. Near-surface ores fill extinct mud geysers and the deep deposits are chambered veins, stock-works in brecciated blocks, and replacements in limestone. The epigenetic minerals livingstonite, stibnite and sulphur occur in limestone, gypsum and dolomite through a developed vertical range of 260 meters. The deepest workings expose an increased amount of stibnite, which probably indicates that the lower limit of mercury mineralization is being approached. A resurgence of heat and water formed geysers over an extended area after the period of mercury mineralization. Mud geysers, which are situated, in the outcrops, contain the secondary mercury minerals, cinnabar and barcenite in the gravel and mud filling the vents. A 150-ton flotation plant is in operation concentrating stope fills that assay 3.0 kg. of mercury per ton. In one open stope, which is more than one hectare in area and 60 m. high, 150,000 tons are available. INTRODUCTION The Huitzuco mercury mines are of interest because of the unusual occurrence of ore in extinct geyser vents and the presence of several rare mercury minerals. Some of the deposits have typical characteristics of the telethermal zone and there is a gradation towards typical epithermal mineralization in depth. Halse,1 Villarello,2 Mactear3 and Merrill4 have described the geology and the early operations in the district, and Barcena5 and Mallet6 have described the rare mercury minerals, livingstonite and barcenite, found at Huitzuco. LOCATION The village of Huitzuco lies in the north central part of the State of Guerrero, Mexico, 27 km. (16.7 miles) east of Iguala, which is the largest and most important town in the area. Iguala is served by the Mexican National Railways and also by the Mexico City-Acapulco highway. The highway is surfaced from Mexico City to Iguala, a distance of 200 km. (124 miles) by road, and there is a fairly good, level, dirt road from Iguala to Huitzuco. The elevation above sea level is about 1000 m. (3280 ft.). The climate is warm and very dry except during the rainy season, from June to

Jan 1, 1937

By E. C. Babson

In order to explore the possibility of predicting reservoir performance from laboratory data, behavior of a hypothetical low-permeability reservoir has been estimated by applying data and methods currently available in the literature. A method of calculating decline in productivity index is discussed, and recoveries by internal gas drive, external gas drive and water drive are estimated. Introduction During the life of a producing oil property an operator is faced with many perplexing problems. Any attempt to determine proper well spacing, optimum rate of production, or the desirability of pressure maintenance requires the evaluation not only of a host of economic and practical operating factors but also of the future performance of the reservoir. Although in some cases economic or operating con-siderations may be of primary importance in planning a development or production program, the anticipated effect on ultimate recovery is more likely to be the decisive factor. The soundest basis for evaluating reservoir performance is past experience with oil fields, but pertinent data are difficult to obtain or apply under conditions normally encountered in California fields. Many of these fields are characterized by thick sections of alternating sands and shales complicated by faulting and rapidly changing lithologic conditions. Further compli- cations are introduced by haphazard development and production practices resulting from competitive conditions, changing demand for oil, and insufficient knowledge of structural conditions during early development. Even in the rare cases where development has been systematic and adequate, production policy has usually been controlled by economic and competitive factors rather than a desire to obtain information for use in future operations. In other words, comparable reservoirs in which development and production practices have been systematically varied are seldom found. In the light of these conditions, conclusions based on experiences usually lack the certainty required for decisions involving large sums of money. Some other method of attacking these problems is needed to supplement and orient field experience. Progress in laboratory investigations of the flow of oil, gas, and water through sands has been so rapid in recent years that these data may furnish such a supplementary approach in the near future. In order to explore this possibility the author has attempted to predict the behavior of one type of reservoir by applying published data and methods. Basic Data and Assumptions Calculations outlined in this paper are dependent upon a detailed knowledge of the properties of oil, gas, and water present in the reservoir and the portion of the total pore space originally filled by each. It is also necessary to know how the permeability of the sand to oil, gas, and water varies with the saturations of these fluids 20

Jan 1, 1944

By E. F. La Vigne

ON Aug. 10, 1884, the Retsof Mining Co. began the sinking of an 18 by 12-ft. shaft at Retsof, N. Y. Rock salt was reached in 1885, in September, at 1008 ft. below the surface. The first salt was shipped in the fall of 1885. A timber breaker was built in 1886. In July, 1895, there was a consolidation of the Retsof Mining Co., the Greigsville Salt & Mining Co., the Livonia Salt Co., and the Lehigh Salt & Mining Co. These consolidated salt companies are now known as the Retsof Mining Co., a subsidiary of the International Salt Co. Eventually all of the mines were closed except the mine of the Retsof Mining Co., at Retsof, Livingston County, New York. On July 6, 1921, about ½ mile south of the original shaft and plant of the Retsof Mining Co., a new 9 by 28-ft. concrete-lined shaft was started. The shaft is 1063 ft. deep from the top of the shaft collar to the bottom of the salt bed. At the same time a reinforced-concrete breaker and other buildings were erected. This new plant began opera-tions on Dec. 15, 1923. It was designed for a capacity of 3000 tons in 8 hours.

Jan 1, 1936

By H. Rosenthal, A. L. Jamieson

Stress-corrosion cracking of copper-base alloys is of considerable importance and has been the subject of many investigations which employed various accelerated tests and long-time service tests. The outstand¬ing accelerated tests used are variations of either the mercury cracking test reported by Rogers in 1905( 1)2 or the ammonia test reported in 1910(2). The ease of applica¬tion of the mercury test is probably the reason industry adopted it. Subsequent investigation of this test(3,4) revealed that a minimum threshold stress was necessary before mercury cracking could develop. Since season cracking has been found in some instances in caliber 0.3o ammunition which has passed the mercury test, it is evident that the threshold stress value of the mercury test may be too high for dis¬tinguishing between acceptable and un¬acceptable caliber 0.30 cartridge cases. This condition has naturally led to the study of an ammonia test with its ability to cause cracks with almost any stress level. But the lack of a definite threshold value means that standards are necessary for evaluating the results of the ammonia test.

Jan 1, 1945

By H. H. Stoek

A study of Americarf coal-mine practice shows two of its distinctive features to be: A greater number of accidents per thousand employees than in any of the other leading coal-producing countries; a much greater percentage of the coal lost than in any of the other leading coal-producing countries. Although our subject is mainly concerned with the second feature, any consideration of mining methods should include safety, efficiency, and economy or costs. If the argument could be offered that our wasteful mining was necessary on account of safety, and that it is carried out with less loss of life than in other countries, the plea for conservation of coal could not he so strongly urged. But when we are wasteful of both life and property, the subject merits more: consideration than it has received. Some coal operators will doubtless say that the unit of accidents should be the number per million tons produced rather than per thousand employees, for by adopting this unit America probably stands in the lead rather than the lowest among the countries. However, vital statistics are not usually so expressed by other governments, by life and accident insurance companies, or in other industries, and it is merely begging the question and attempting to bolster up a bad condition to adopt a peculiar unit for the statement of our accidents. For many years the statement was made by various agencies, and was unchallenged, that "For every ton of bituminous coal mined in the United States a ton had been lost in the way of pillars left in the mines." This statement was undoubtedly true for many years, and although in the past decade some progress has been made toward obtaining a higher extraction, and in some districts very decided progress, the loss is still great; and, although no exact data can be given, it is probable that for the United States as a whole at least one ton is lost for every two mined.

Jan 1, 1923

By L. Wahl, M. Allard, B. Trentini

REMOVAL of sulfur in steelmaking is presently a problem of utmost importance as requirements on final sulfur contents in finished steels become increasingly strict. This is in spite of often increased sulfur contents in the fuels used during the different stages of steel processing. According to local conditions or current economic factors, sulfur can be removed during one or more of the processing operations; for instance, in a blast furnace operated under high temperatures and with a high slag basicity ratio and also by means of high inputs of manganese into the burden. These methods of proceeding are, however, expensive and in contradiction with the acid practice which is gradually being developed owing to the fact that it allows coke and lime savings and usually permits an increase of productivity. In the melting-shop, desulfurization can proceed in the open-hearth or electric furnace with one or several very basic slags, or with special prefused slags (Perrin process) mixed with steels poured from the open-hearth, electric furnace, or converter. Liquid pig iron has also been treated separately before being used in the melting shop, in order to reduce high sulfur contents. This external desul-furization has been developed in Europe for the basic Bessemer Thomas process, which is again in favor owing to the great flexibility of such installations and to the fact that the steel produced is not polluted by impurities coming from the scrap. Since the basic Bessemer process, as usually practiced, has a low desulfurizing power, external desulfurization is generally carried out in ladles by means of alkalies such as soda ash. This method, which has the advantage of being simple and costing little, has only a medium desulfurizing power, which implies the necessity for repeating the operation several times when a substantial amount of sulfur has to be removed or when very low sulfur contents are desired. Thermal losses are high and there is a considerable decrease in output. Moreover, the resulting fluid and corrosive slag, which is extremely difficult to eliminate, attacks the refractory linings of the mixers and steel furnaces. Therefore, it seems necessary to devise a simple method for external desulfurization which would not only remove substantial quantities of sulfur from the hot metal coming from an acid blast furnace, but which would also bring the sulfur contents down to the low level required in the making of high quality steel and iron. Principle of the Process In this paper a new method will be described for desulfurizing hot metal. It has been perfected by

Jan 1, 1958

By P. Datta, L. L. Handy

For a wetting phase displacing a nonwetting phase from a porous medium the distribution of the residual fluid may depend on displacement conditions. Although this subject has been debated in the literature, only a few experiments have been cited to support the various conclusions. Experimental results presented in this paper show that fluid distributions are dependent on imbibition pmcedures. Results agree qualitatively with predictions from the pore doublet model. If the rate of water imbibition is restricted, the nonwetting phase is trapped preferentially in .the larger pores as expected. But if the rate of water imbibition is unrestricted, trapping occurs somewhat more in the smaller pores. These conclusions were deduced primarily from relative permeability measurements. INTRODUCTION Relative permeabilities are known to depend on the saturation history of the porous medium. For either continuously increasing or continuously decreasing wetting phase saturations, however, they have normally been assumed to be single-valued functions of saturation. Severat investigators have compared relative permeabilities measured by different methods and have reported acceptable agreement.1-5 Studies of simple models of the displacement process suggest that the distribution of residual fluids can be influenced by the displacement method. If this is so, relative permeabilities also should depend on the method of displacement. These predictions have not been supported by experimental data. The object of this paper is to investigate experimentally some of the predictions of these model studies. The particular question of importance is whether steady-state and unsteady-state methods should be expected to give the same values of relative permeability. Much of the reported data showing agreement between steady-state and unsteady-state methods have been obtained on un consolidated sand. Johnson, Bossler and Naumann, however, compared steady-state and unsteady-state results for Weiler sandstone and found no significant differences.5 Levine made a detailed study of pressure and saturation distributions for a laboratory waterflood in a consolidated system but made no attempt to calculate performance from steady-state relative permeability data Bail and Marsden in a somewhat similar set of experiments did attempt a comparison of observations with predictions but the results were inconclusive.7 Excluding gravity, two forces affect the distribution of wetting and nonwetting phases during an unsteady-state, immiscible displacement: viscous and capillary forces. If relative permeabilities are indeed the same when measured by steady- or unsteady-state methods, the fluid distributions at the same fluid saturations must be similar for both methods. Furthermore, the implication is that the relation between capillary and viscous forces is the same for both methods insofar as the effect on microscopic fluid distributions is concerned. Unsteady-state displacements are normally run at high rates to maximize the ratio of the viscous to capillary forces. The objective is to reduce the effect of capillary forces on macroscopic fluid distributions. For floods in which the phase which wets the porous medium displaces the nonwetting phase, capillary forces compete with viscous forces in determining fluid distributions.8 The residual nonwetting phase is discontinuous. Competitive aspects of viscous and capillary forces and the resulting effect on water-oil distribution in porous media have been illustrated in an elementary way using a pore doublet model. This model and predictions from it have been discussed at considerable length by Rose and Witherspoon, Rose and Cleary and by Moore and Slobod.9-13 Rose and Witherspoon show that so long as water invades the model at a rate equal to or greater than the free imbibition rate, the water will move through the larger capillary of a doublet first and trap oil in the smaller capillary. On the other hand, if a negative pressure is applied to the water

Jan 1, 1967

By J. S. Hegwer, P. M. Dunlap

An improved acid for the treatrrzent of sulfate-con-raining limestones and dolomites is described. The acid is designed to reduce he reprecipitation of dissolved calcium sulfate and the possibility of plugging permeable flow channels. In addition, this improved acid has a much lower reaction rate than that of regular acid; the advantages of a "retarded" acid are obtainable. Field testing of the acid has shown it suitable for use in sulfate-containing formations. Substantial improvements in productivity generally resulted. INTRODUCTION Acid treatments of limestones, dolomites and other formations bearing carbonate deposits are frequently unsuccessful when the calcareous formation contains sulfate, either as anhydrite (CaSO,) or gypsum (CaSO4. 2H2O). Preliminary dissolution in acid followed by redeposition of calcium sulfate appears to be a major factor contributing to poor well performance after acidizing. The precipitate is usually the gypsum form of calcium sulfate, but in higher temperature formations it may be anhydrite. The freshly precipitated crystals are nearly always very small and needle-like. They may occupy a gross volume many times that of the original anhydrite crystals and will obviously constitute an impediment to flow through newly enlarged flow channels. It is believed that the redeposition problem is most severe when anhydrite lines the fracture systems and large pores which supply the effective permeability of a formation. Microscopic inclusions of calcium sulfate also present large sulfate surface areas for dissolution in acid. In either case, great amounts of calcium sulfate may dissolve before the acid can be spent on formation carbonates. For regular spent acid (originally 15 per cent hydrochloric acid) the precipitate could be as much as 270 Ib gypsum/1000 gal acid. Two techniques have been applied by the industry for reducing sulfate plugging during acidizing. The method'.' commonly employed in the field is the attempted removal of a quantity of regular treating acid before it has reacted completely with the formation. This is practiced because the solubility of calcium sulfate is greater in a solution that is still acidic than in one which has been largely spent on the formation rock. The chance of precipitative plugging is therefore reduced if the withdrawal is successful. However, it is often impossible to get the acid out of the formation before precipitation occurs. A second possible method, which at first glance appears practical, involves addition to the acid of sequestering agents which form strong soluble complexes with calcium ions. These chemicals do increase the "solubility" of calcium sulfate in fresh acid, but to a lesser extent in spent acid. The sequestering agents have, therefore, proved unsatisfactory because the amount of sulfate eventually deposited from the spent acid may be greater than that from regular acid. Another logical approach to the problem of calcium sulfate reprecipitation is the prevention of the initial dissolution of calcium sulfate by the common ion effect. This may be accomplished by adding a soluble calcium salt to the fresh acid. The use of calcium salts in treating acids is not entirely new. An earlier suggested use of a soluble calcium salt in hydrochloric acid apparently failed to recognize the full extent to which the solubility of calcium sulfate could be suppressed. The present study extends this earlier work and adds certain improvements toward the development of a practical anti-anhydrite acid. LABORATORY DEVELOPMENT Calcium Sulfate Solubility Table 1 shows the results of a laboratory study performed to establish the effect of calcium chloride concentration on gypsum solubility. Because of the strong tendency of calcium sulfate to form supersaturated solutions, accurate solubilities are difficult to determine. These solubility data probably are reliable to within ± 15 per cent. The solubility of calcium sulfate in 15 weight per cent hydrochloric acid increases with increasing temperature. This trend is also followed in hydrochloric acid which cantains calcium chloride. This is contrary to the solubility behavior of calcium sulfate in water, wherein the solubility decreases with increasing temperature.