Search Documents

By H. A. Jr. Koch, C. A. Hutchinson

Miscible phase displacement of oil from reservoirs has been emphasized in the past few years. The reason for this emphasis lies in the high oil recovery attainable by this process. Removal of capillary effects in the reservoir leads to recoveries approaching 100 per cent in the area contacted by the miscible phase. The miscible slug process is one means of obtaining a miscible displacement. Here a band or slug of I,PG is injected into the reservoir prior to gas injection. The idea is to maintain the band of LPG "wedged" between the gas and oil phases and thus achieve a miscible phase displacement. A second method lor achieving miscibility is through the injection of a gas which is not miscible with the reservoir fluid but which develops a zone of miscibility in [he reservoir through mass trans-ier with the reservoir oil.' This mass transfer results in either an enrichment of the lean injected gas by intermediates from the oil or an enrichment of the oil by intermediates from a rich injection gas or one that has been enriched on the surface by LPG addition. We are interested here in discussing the process in which miscibility is developed at the displacement front by the evaporation of interrnediatcs from the oil phase into the gas phase. This process "builds up" its own slug of miscible material at the displacement front and therefore does not require the injection of LPG to obtain miscibil-ily. Each process has its own area of applicability. Generally, the high pressure gas process is applicable only with reservoir fluids which con-!ain a high concentration of inter- mediates. If the high pressure gas process is technically feasible at pressures less than 4,500 psi, it is probably more desirable economically than the slug process. The slug process has broad applicability in the shallower reservoirs and with reservoir fluids which contain a relatively low concentration of LPG and natural gasoline constituents. This paper deals with some new concepts of the high pressure gas injection process where it is proposed that flue gas can be substituted for hydrocarbon gas without sacrificing our goal of miscibility. MECHANISM Introduction Considerable effort has been devoted to study of the mechanics ot the high pressure gas injection proc-one generalization result-ing from some of these studies was that the composition of the injected gas is relatively unimportant in establishing the miscibility pressure* for a given reservoir fluid. This generalization is correct for the composition range of gases typically encountered in the field. Two such gases are a gasoline plant tail gas containing 85 per cent methane and 15 per cent ethane, and a field separator gas containing 70 per cent methane and 30 per cent heavier components. The most important factor which sets the miscibility pressure in the operation is the reservoir fluid composition, particularly the concentration of LPG-natural gasoline constituents. The injected gas is the agent by which the LPG-natural gasoline constituents are concentrated at the displacing front to create a miscible displacement. Based on these results, it appeared feasible that some inexpensive gas, such as flue gas, might be substituted for hydrocarbon gas for use in the high pressure gas process. A re-examination of the phase relations of the high pressure gas injection process should clarify the principle behind using flue gas (essentially nitrogen) as an injection gas. Three Component Diagram The phase relations of the high pressure gas injection process have been illustrated by the use of the three component diagrams.'," In Fig. 1 we have arbitrarily represented the multi-component reservoir system by three components; methane, ethane through hexane, and heptanes plus. The solid curve ABC is the phase boundary curve. It represents the locus of compositions which have fixed saturation pressure at a fixed temperature; the lower branch AB shows bubble point compositions, the upper branch BC, the dew point compositions. Point B is the coniposition of the critical mixture at this temperature and pressure. The dashed lines (tie lines) connect vapor and liquid compositions which are in equilibrium. Let us consider Reservoir Fluid D which we wish to displace in 21 miscible manner by gas injection. Let us further restrict the discussion to the case where miscibility between an injection gas and the reservoir fluid at the displacement front is developed by gas enrichment in the reservoir. For this case, any gas whose composition lies between Points C and E on the right side of the three component diagram can be used to give a miscible displacement of Reservoir Fluid D. This is true because the more mobile injected gas moves faster than the displaced oil and is in continuous contact with virgin oil at the displacement front. This leads to a continuing enrichment 01' the gas at the displacement front by evaporation of the C, - C,

By L. W. Saperstein, D. Yeung, L. B. Phelps

Introduction The success of preventive methods for the mitigation of coal mine drainage formation will require a marriage of the minimization of initial coal mine drainage formation, the minimization of toxic fluid formation after toxic material disposal, the minimization of the mobilization and transpor¬tation of formed toxic fluids, and the maximization of the rate of diultion and attenuation of the formed toxic fluids. This paper contributes to the understanding of factors af¬fecting mobilization and dilution and attenuation of formed toxic fluids. When water containing a salt content different from in situ pore water in the soil is passed through a body of soil, the concentration of salts in the outflow will gradually change composition in a manner that depends on the kinds of hydraulic processes that occur in the soil. These processes are molecular diffusion, lateral dispersion, longitudinal dispersion, chemical reactions or exchange, physical adsorp¬tion, and biological retardation. This note considers only the first three processes. These three microscopic processes can be analyzed statistically on a probability basis. Such results, confirmed experimentally, indicate that a tracer introduced instantaneously as a point source will tend to form a Gaussian normal distribution as it moves downstream (Todd, 1964). Dilution During Flow The closed-form soltuion for pulse or instantaneous injec¬tion of a tracer during confined flow in a homogeneous porous medium shows that the maximum tracer concen¬tration at a point in space, x, after the time interval, t*, is given by [ ] where Aa is the effective flow cross-sectional area; A is the column cross-sectional area; a is soil porosity; M is mass of the injected tracer; C is concentration of the tracer in the permeating fluid and is a function of x and t*; D is the longitudinal dispersion coefficient; and va is the interstitial fluid velocity (Klotz and Moser, 1974). Therefore, the following conclusion can be made: • For a medium with a constant longitudinal dispersion coefficient, D, a constant soil porosity, a, a constant cross¬sectional area, A, and a fixed mass of injected tracer, M, Cmax will decrease as the time of peak outflow concen¬tration t* increases. • For a medium with a constant longitudinal dispersion coefficient, D, a constant soil porosity, a, a constant cross¬sectional area, A, a fixed mass of injected tracer, M, and a constant interstitial fluid velocity, va Cmax will decrease as the distance of travel, x, increases. • For a medium of constant cross sectional area, A, con¬stant soil porosity, a, a constant mass of injected tracer, M, and a fixed distance of travel, x, Cmax will decrease as D/va increases. Klotz and Moser (1974) concluded that D is about proportional to no.3 where r) is the kinematic viscosity; D is about proportional to a-3 where a is soil porosity; D in¬creases with increasing grain size; D increases as grains become less spherical; D increases with greater grain rough¬ness and angularity; D increases with increasing uniformity coefficient; and D is significantly affected by grain size and uniformity coefficient. The remaining parameters are not significant. Numerical Simulation Studies Numerical simulation studies were used to investigate the nature of flow and the optimum length of a toxic package within a saturated porous medium of fixed dimensions and configuration (Fig. 1). The width and position of the package was maintained constant (Phelps et al., 1981). Results indicate that if the package extends throughout the length of the model, the flow is vertically downward and

Jan 1, 1984

NATURE produces iron ore abundantly in many regions of the world, especially in Italy where not only is there a great abundance of it but also there are various kinds. In these our Tuscan parts it is a very familiar thing, since we are situated close to the island of Elba which is so overflowing and rich in this ore that it surpasses every other place where it is found. Thus not only do the regions of Tuscany share its great quantity because of their proximity, but more than two-thirds of Italy as well as Sicily and Corsica are supplied, and perhaps some more distant place. In addition, this ore is of such perfection that it

Jan 1, 1942

By C. S. Allen

With increased coal production and mechanization of coal mines many transportation problems arise. The main objective is to bring the coal to the tipple or dump it as quickly as possible. Larger and faster haulage locomotives or two locomotives connected in tandem have been adopted to solve the problem. Motor equipment, gears and control systems of locomotives to be placed on these hauls are carefully studied to meet these requirements, by an analysis of motor characteristic curves with the corresponding tractive effort curves, in order to determine the correct load for maximum efficiency and to determine the approximate schedule. Control equipment is usually considered to be the controller and resistance. Sometimes accelerating curves are calculated in order to obtain smooth starting in the least possible time without slipping the wheels. Train control is very important, but why limit this to acceleration ? Deceleratien-or-retardation of the locomotive is a part of the train control and should be given as much consideration as the control for acceleration. Types or Braking Common braking systems for mine locomotives utilize screw-type mechanical brakes, dynamic braking and the air brake. For gathering and haulage locomotives, the srrew-type mechanical brake is regarded as standard. A brake of this kind cannot be applied without much effort and lapse of time. Motormen, like other people, follow the path of least resistance, and therefore have their brakes ready for instant application—which means that the shoes are virtually dragging. Even then, a motorman bucks and plugs the motors to gain time and avoid as much physical effort as possible. "Bucking of motors" consists in turning the reverse cylinder of the controller to parallel position corresponding to the opposite direction of travel while the locomotive is in motion, without applying power from an external source. When this occurs, both motors tend to act as series generators, because the armatures are revolving and there is residual magnetism in the field circuit. Owing to slight differences in motor manufacture, one of these will generate a slightly higher potential and will overcome the generated voltage of the second and tend to drive it as a motor in the reverse Direction.-This action retards the locomotive but is very severe on the segments of the reverse cylinder and on the motor commutators. "Plugging motors" is the application of power to the motors corresponding to the opposite direction of travel. In order to "plug" the motors it is necessary first to "buck,, them (which reverses the connections to the motors) and then to apply power. Theoretically, this should be done only in an emergency, but locomotives in mine service are frequently thus treated., Dynamic braking is retardation of the locomotive by the motors acting as generators, which take no power from the line.

Jan 1, 1942

By C. S. Allen

With increased coal production and mechanization of coal mines many transportation problems arise. The main objective is to bring the coal to the tipple or dump it as quickly as possible. Larger and faster haulage locomotives or two locomotives connected in tandem have been adopted to solve the problem. Motor equipment, gears and control systems of locomotives to be placed on these hauls are carefully studied to meet these requirements, by an analysis of motor characteristic curves with the corresponding tractive effort curves, in order to determine the correct load for maximum efficiency and to determine the approximate schedule. Control equipment is usually considered to be the controller and resistance. Sometimes accelerating curves are calculated in order to obtain smooth starting in the least possible time without slipping the wheels. Train control is very important, but why limit this to acceleration ? Deceleratien-or-retardation of the locomotive is a part of the train control and should be given as much consideration as the control for acceleration. Types or Braking Common braking systems for mine locomotives utilize screw-type mechanical brakes, dynamic braking and the air brake. For gathering and haulage locomotives, the srrew-type mechanical brake is regarded as standard. A brake of this kind cannot be applied without much effort and lapse of time. Motormen, like other people, follow the path of least resistance, and therefore have their brakes ready for instant application—which means that the shoes are virtually dragging. Even then, a motorman bucks and plugs the motors to gain time and avoid as much physical effort as possible. "Bucking of motors" consists in turning the reverse cylinder of the controller to parallel position corresponding to the opposite direction of travel while the locomotive is in motion, without applying power from an external source. When this occurs, both motors tend to act as series generators, because the armatures are revolving and there is residual magnetism in the field circuit. Owing to slight differences in motor manufacture, one of these will generate a slightly higher potential and will overcome the generated voltage of the second and tend to drive it as a motor in the reverse Direction.-This action retards the locomotive but is very severe on the segments of the reverse cylinder and on the motor commutators. "Plugging motors" is the application of power to the motors corresponding to the opposite direction of travel. In order to "plug" the motors it is necessary first to "buck,, them (which reverses the connections to the motors) and then to apply power. Theoretically, this should be done only in an emergency, but locomotives in mine service are frequently thus treated., Dynamic braking is retardation of the locomotive by the motors acting as generators, which take no power from the line.

Jan 1, 1942

By Allen J. Johnson

It is probable that the word "anthracite" was derived from the Greek preposition an, and the Greek word for Thrace, meaning, in combination, "toward or near Thrace." Aristotle, Theophrastus, Strabo and Pliny all mention Thrace, or Samothrace, in treatises upon stones and stone coals dating back to about 371 B.C. In 1769 Obadiah Gore, a blacksmith of Wilkes-Barre, successfully burned anthracite in his forge, the first of millions of consumers of Pennsylvania anthracite. The Anthracite Region While anthracite is found in widely scattered locations throughout the world, 99 per cent of the total production of the United States origintitles within an area of 3300 square miles in castern Pennsylvania, less than 500 square miles of which arc underlain by workable coal beds. Eminent authorities such as the United States Geological Survey agree that this Pennsylvania anthracite is the only true anthracite east of the Rocky Mountains. There is some graphitic anthracite in Rhode Island but it is not suitable for combustion; and coals from such states as Virginia and Arkansas, frequently sold as anthracite, are in reality semi-

Jan 1, 1934

By Edward Ernst, Richard Runvik

AT the U. S. Gypsum Co. mine in Oakfield, N. Y., a flat-lying vein of rock gypsum is mined by the room and pillar method. Averaging only 4 ft thick, this vein is 1200 to 6000 ft in mineable width and many miles in length. Overlying the vein throughout the mine is a 2-ft thickness of distintegrated gypseous shale and fractured limestone which parts easily, falling with little or no warning. This shale, known as ash, varies in thickness from less than an inch to more than a foot. Small veinlets of selenite cut this shaley material, which breaks around timber props. The 18-in. limestone over-lying the ash is fractured vertically into blocks of varying size and will fail if any but the shortest unsupported spans are permitted. Above these two members is a thick layer of competent limestone.

Jan 6, 1957

By Mark Sheppard

DuRing the winter of 1937, the writer visited a West Virginia stone quarry at which the overburden is stripped hydraulically. The quarry is in a bed of limestone, about 200 ft. thick, which outcrops on a hillside above a small river; the quarry face is 175 ft. high. The top of the stone is cut in all directions by erosion channels, which are filled with a tough, red clay. Some of the larger channels are 30 ft. deep and 8 ft. wide. The thickness of the clay overburden ranges from a few inches to 10 ft., the average being estimated as less than 3 feet. The topography of the district is rugged, and the hillside above the quarry face is not suited to the use of the usual mechanical methods of moving dirt. Until hydraulicking was started 10 years ago, the overburden was dug by hand labor, dumped to the quarry floor and transported to the dump in quarry cars. Cleaning deep channels was a slow and expensive process. When hydraulicking was started, the top of the quarry face was over 200 ft. above the level of the river. The pipe line was carried in a semicircle around the top of the quarry about 200 ft. from the face and about 50 ft. above it. As there is no adequate supply of water above the quarry, the water must be pumped from the river. As quarrying progressed the pipe line was moved until the discharge points are now over 300 ft. above the river. Water is pumped from the river by a four-stage centrifugal pump having a 5-in. intake and a 4-in. discharge. It is direct-connected to a 200-hp., 2300-volt, 1760-r.p.m. induction motor. At 1760 r.p.m. the rated capacity of the pump is 750 gal. per minute under a head of 600 ft. The pump is installed in a house of frame construction on the river bank, about 10 ft. above normal water level, which also houses the pump for the mill-water supply. Above the pumps are hoisting bays into which the motors are raised whenever the river reaches flood stage. An 8-in. suction line, equipped with a strainer and a foot valve, takes the water from a concrete sump at the edge of the river. The pipe line from the pump consists of 1750 ft. of 8-in. spiral steel flanged pipe and

Jan 1, 1938

By Mark Sheppard

DuRing the winter of 1937, the writer visited a West Virginia stone quarry at which the overburden is stripped hydraulically. The quarry is in a bed of limestone, about 200 ft. thick, which outcrops on a hillside above a small river; the quarry face is 175 ft. high. The top of the stone is cut in all directions by erosion channels, which are filled with a tough, red clay. Some of the larger channels are 30 ft. deep and 8 ft. wide. The thickness of the clay overburden ranges from a few inches to 10 ft., the average being estimated as less than 3 feet. The topography of the district is rugged, and the hillside above the quarry face is not suited to the use of the usual mechanical methods of moving dirt. Until hydraulicking was started 10 years ago, the overburden was dug by hand labor, dumped to the quarry floor and transported to the dump in quarry cars. Cleaning deep channels was a slow and expensive process. When hydraulicking was started, the top of the quarry face was over 200 ft. above the level of the river. The pipe line was carried in a semicircle around the top of the quarry about 200 ft. from the face and about 50 ft. above it. As there is no adequate supply of water above the quarry, the water must be pumped from the river. As quarrying progressed the pipe line was moved until the discharge points are now over 300 ft. above the river. Water is pumped from the river by a four-stage centrifugal pump having a 5-in. intake and a 4-in. discharge. It is direct-connected to a 200-hp., 2300-volt, 1760-r.p.m. induction motor. At 1760 r.p.m. the rated capacity of the pump is 750 gal. per minute under a head of 600 ft. The pump is installed in a house of frame construction on the river bank, about 10 ft. above normal water level, which also houses the pump for the mill-water supply. Above the pumps are hoisting bays into which the motors are raised whenever the river reaches flood stage. An 8-in. suction line, equipped with a strainer and a foot valve, takes the water from a concrete sump at the edge of the river. The pipe line from the pump consists of 1750 ft. of 8-in. spiral steel flanged pipe and

Jan 1, 1938

By J. C. Cordell, C. F. Weinaug

A study of the behavior of retrograde condensation from gas mixtures was made in the presence and absence of sand in order to determine if the condensed liquid would re-vaporize in the Presence of sand. Methane-butane and methane-pentane mixtures that would form liquids by retrograde condensation when produced from a constant volume cell were used. The methane-butane mixtures of similar composition were produced by three different methods. The first two were charged into an empty cell and were produced in one case within a period of 9 hr and in the other within a period of 3 days. The third mixture was charged to a sand-packed cell and produced within a period of 9 hr. The curves relating composition of the produced gas to pressure obtained from these experiments show that equilibrium was maintained as long as liquid was condensing. However, during the portion of the pressure decline where the condensed liquid should be revaporizing, equilibrium was maintained only when the mixture was produced from the sand-packed cell. The methane-pentane mixture is produced only in the presence of sand. The data obtained for this system also show that equilibrium is maintained at all times during the pressure decline. These results indicate that revaporization is aided rather than prevented by the fact that the condensate "wets the sand." The significance to the petroleum industry of the behavior of hydrocarbons in the retrograde region is becoming increasingly important because a large percentage of reservoirs being discovered today arc of the gas-condensate type. The important characteristic of a gas-condensate reservoir is the retrograde condensation of a liquid phase throughout the reservoir if the pressure is allowed to decline. In order to prevent the loss of this retrograde liquid in some of these reservoirs, they are "cycled"; that is, the material produced from the reservoir is processed to remove the heavier hydrocarbons and the light fractions are returned to the reservoir to maintain the reservoir pressure. Another method of producing these reservoirs is Pressure depletion. There are other methods but they are not in general use. Although a large number of factors are involved in determining the optimum method of producing a reservoir, only the problem of whether the retrograde condensate resulting from pressure depletion will revaporize from sand at equilibrium conditions is considered in this paper. Also the data are limited to the methane-n-butane and the methane-n-pentane systerns at loo°F and one type of sand. Three types of tests were run in order to compare the revaporization of retrograde liquid formed in a cell with that formed in a sand-packed cell, and to establish the effect of time. The results of tests presented in this paper indicate that both time and the presence of sand promote the revaporization of

Jan 1, 1949

By George E. Beavers

It is well to understand at once that converter gas is always mixed with copper blast-furnace gas at Copperhill before entering the Glover tower, and, at times, roaster gas is also added along with the converter and blast-furnace gas. Fig. 1 is introduced to show the variations in the sulfur dioxide content of the gas and the ability of the acid-plant operator to control the variations, resulting in a very even grade at the Gay-Lussac tower entrance. The sulfur dioxide content of the gas entering the Gay-Lussac tower must be low and regular to assure low niter consumption. The blast-furnace gas alone is rather uniform as regards sulfur dioxide content and the variations, as shown in Fig. 1, are chiefly caused by converter changes—out for charging, slag pouring, copper pouring, and, of course, the "finish." The combined gas during the converter finish is, at times, almost free of oxygen and the sulfur dioxide content reaches 13.0 per cent. At such times air is added at the Glover tower.

Jan 1, 1934

By Donald W. Scott

Generally speaking, there is nothing very difficult about taking good microgrztphs of photogenic thin sections or grains with a petrographic microscope-camera setup. However, sometimes it is desired to show some detail that cannot be illustrated satisfactorily by the usual micrographs taken with parallel polarized light, with crossed nicols, or even with two micrographs. A simple procedure giving good results has been used at Battelle Memorial Institute for subjects falling into this classification, and it is believed to be of interest, especially to research people who must sell a point to executives through the medium of well-illustrated reports. The following problem illustrates a typical application: It is desired to photograph a thin section of an iron ore to illustrate the character and association of the iron oxides and the individual quartz crystals. A magnification of 75 dia. is acceptable. A micrograph of the field in question (Fig. Ia) was taken with parallel polarized light. Due precaution was taken to provide critical illumination, correct exposure, a sharp focus, a good darkroom technique, and other essential conditions. It illustrates correctly the iron oxides, but it fails to show the individual quartz crystals. A micrograph of the identical field (Fig. Ib) was taken under the same precise conditions, but with crossed nicols. It gives a better idea of the character of the individual quartz crystals but is likely to be misinterpreted unless accompanied by a lengthy descriptive note. This micrograph suggests that the centrally located, large black area is composed entirely of iron oxides. That this' is an incorrect interpretation is evident by reexamining the micrograph of Fig. Ia. The correct interpretation is that the dark area contains quartz crystals oriented with their optical directions parallel to, or nearly parallel to, the vibration directions of the polarizer and analyzer of the microscope. Thus, the executive, or anyone who had not done the work personally, would get no more than a fair interpretation, even if two micrographs were included; and in the interests of both brevity and clarity, one micrograph usually is more desirable. Exactly how many quartz crystals occur in this region cannot be told from the two micrographs, and a printing of the two negatives in register would likewise not show the detail desired. Thus, it is evident that some subjects cannot be satisfactorily illustrated by the usual procedures. In photographing Fig. Ic the light was subdued and, during the entire exposure of 75 sec., the analyzer nicol was rotated uniformly in its mounting from a crossed position to 45° uncrossed position to introduce the desired amount of contrast in the various individual quartz crystals. The true reproduction of the character and association of the iron oxides, and the additional structure and detail in the quartz areas, is apparent. It might be

Jan 1, 1949

By Donald W. Scott

Generally speaking, there is nothing very difficult about taking good microgrztphs of photogenic thin sections or grains with a petrographic microscope-camera setup. However, sometimes it is desired to show some detail that cannot be illustrated satisfactorily by the usual micrographs taken with parallel polarized light, with crossed nicols, or even with two micrographs. A simple procedure giving good results has been used at Battelle Memorial Institute for subjects falling into this classification, and it is believed to be of interest, especially to research people who must sell a point to executives through the medium of well-illustrated reports. The following problem illustrates a typical application: It is desired to photograph a thin section of an iron ore to illustrate the character and association of the iron oxides and the individual quartz crystals. A magnification of 75 dia. is acceptable. A micrograph of the field in question (Fig. Ia) was taken with parallel polarized light. Due precaution was taken to provide critical illumination, correct exposure, a sharp focus, a good darkroom technique, and other essential conditions. It illustrates correctly the iron oxides, but it fails to show the individual quartz crystals. A micrograph of the identical field (Fig. Ib) was taken under the same precise conditions, but with crossed nicols. It gives a better idea of the character of the individual quartz crystals but is likely to be misinterpreted unless accompanied by a lengthy descriptive note. This micrograph suggests that the centrally located, large black area is composed entirely of iron oxides. That this' is an incorrect interpretation is evident by reexamining the micrograph of Fig. Ia. The correct interpretation is that the dark area contains quartz crystals oriented with their optical directions parallel to, or nearly parallel to, the vibration directions of the polarizer and analyzer of the microscope. Thus, the executive, or anyone who had not done the work personally, would get no more than a fair interpretation, even if two micrographs were included; and in the interests of both brevity and clarity, one micrograph usually is more desirable. Exactly how many quartz crystals occur in this region cannot be told from the two micrographs, and a printing of the two negatives in register would likewise not show the detail desired. Thus, it is evident that some subjects cannot be satisfactorily illustrated by the usual procedures. In photographing Fig. Ic the light was subdued and, during the entire exposure of 75 sec., the analyzer nicol was rotated uniformly in its mounting from a crossed position to 45° uncrossed position to introduce the desired amount of contrast in the various individual quartz crystals. The true reproduction of the character and association of the iron oxides, and the additional structure and detail in the quartz areas, is apparent. It might be

Jan 1, 1949

By E. A. Kilinski

THE mineral production of Dutch Guiana has been of little consequence. This is due to several rea-sons. Inaccessibility is probably the greatest factor, for the Guianas are off the main commercial route. More or less closely related causes are the tropi-cal climate and the temperament of the inhabitants. Small quantities of gold have come from Dutch Guiana for many years, and recently bauxite has entered the list of exports. It is likely that other minerals may be found in commercial quantities. The Colony is on the northeast coast of South Amer-ica. It is known by two names, that of Dutch Guiana, and that of Surinam. - British Guiana (Demerara) adjoins it on the west, French Guiana (Cayenne) on the east, and Brazil on the south. It covers an area of approximately 58,000 sq. miles. The population, in the. neighborhood of a hundred thousand,, is small, but the variety of races and the sub-sequent mixtures of these is almost incredible. This unusual and colorful population readily falls into three groups, (1) those of the bush, (2) those of the planta-tion, and (3) those of the towns. The bush people con-sist of two groups, the Indians and the bush-negro. The Indians, of whom there are but a little over two thousand, keep entirely to themselves, lead a. very primi-tive existence, and rarely come into the towns. The bush-negro gives the touch of human life to the thick jungles. A descendant of escaped slaves of by-gone days, he is at present a proud, stalwart, happy, clean, moral, carefree and ease-loving individual-a distinct personality. Work is not his pal, although he does cheerfully that which is necessary for his existence. He will transport passengers and goods in his dugout and guide the stranger through the jungles, but that is all. The plantations employ some negroes, but more Javanese, imported as contract labor from the East Indies. Paramaribo, the only large town in Dutch Guiana, is the center of all government, commercial, and social activities. It has a motley population of 40,000, in-cluding negroes native to Dutch Guiana and many from all parts of the West Indies. In addition, there are Javanese, Chinese, and some Hindus. The two latter groups control most of the retail trade. The Dutch and a few scattered Germans are the only Europeans. All of the higher government offices are held by the Dutch, the others are filled from the ranks of the natives. Marriages and intermarriages among these various groups have produced types that defy almost any effort to decipher an individual's forbears. Dutch is the official language, but among the people a jargon known as Tahki-Tahki holds sway. English is taught in the schools, consequently many speak it, and many more can make themselves understood in that language.

Jan 2, 1928

By W. R. Toeplitz

Probably a more descriptive title would be "Much Ado About Nothing." By "nothing," of course, I refer to the porosity which is the main feature of this type of bearing. Porosity has a decided effect on the manufacturing techniques, the structure and physical properties, the oil content, and on the installation and service of oil-retaining porous bronze bearings. A simple curve can be drawn by plotting specific gravity along the abscissa and percentage of porosity by volume on the ordinate. A bronze composition, analyzing 89 Per cent copper, 9.75 Per cent tin, and 1.25 per cent graphite, has an absolute solid specific gravity of 8.5. At this specific gravity, of course, occurs the point of zero porosity. Conversely, at loo per cent porosity, the specific gravity is zero. A similar curve can be drawn for bearings impregnated with oil; the only change being that the specific gravity at loo per cent oil will be 0.89 if we assume that that is the specific gravity of the lubricant. The curve is useful in determining the oil content by volume for any specific gravity. The normal range of oil content for porous bronze bearings of this composition is from 35 to 16 per cent, which is in the specific gravity range of from 5.8 to 7.3. In addition to the amount of porosity, the type of porosity is important. The first consideration here is that the porosity must be intercommunicating. This can be determined by a number of simple tests. The first method, which is very accurate, is to extract the oil in the bearing by cycling

Jan 1, 1945

By Ian J. Smalley

"Quickclay is an extreme case, it is by far the most mobile of all the common solid materials on the earth's surface. It has both a high water content and a mineral texture that allows it to flow with the utmost ease. A mass of quickclay that has lain undisturbed for thousands of years can be jarred into motion by any sudden shock." The quotation is from the paper by Kerr called, "Quickclay," which was published in Scientific American in 1963. This was probably the most widely read paper on quickclay ever published. It was reprinted by Fred Betz in his Benchmark collection on Environmental Geology (BM 25), A quickclay is an extremely sensitive soil. The sensitivity parameter is produced by dividing the undisturbed shear strength by the remoulded shear strength. If a value greater than 50 is obtained, then the soil can be classified as a quickclay. True quickclays are characterized by a very low remoulded strength of the order of 0.5 kPa. The classic quickclays are found in Scandinavia and Eastern Canada, but the 1964 Alaska earthquake revealed a considerable quick¬clay deposit underlying the town of Anchorage. This was discussed in a classic paper by Kerr and Drew in Engineering Geology in 1967. The Kerr views on quickclays were perhaps most clearly expressed in the paper with Liebling in Geol. Soc. Amer. Bull. in 1965. They suggested that the major critical conditions which contribute to quickclay movement are: substantial quantities of layer lattice silicates of colloidal size (about 40% or more by dry weight), sub¬stantial pore water (44%), a reduction in electrolyte concentration below 5 g/l of salt, and addition of a dispersant. There is still discussion and disagreement about the nature of quickclays and the mechanisms of quickclay slides; the "clay mineral"-based views favored by Kerr still find support, although an alternative "primary mineral" view suggests that it is the finely ground primary minerals

Jan 1, 1985

By C. R. Sandberg, C. A. Connally, N. Stein

This paper describes the results of volumetric efficiency tests on oil well pumps handling gas oil mixtures. The work was performed in a large scale, above ground unit wherein test conditions could be accurately controlled and measured. The main variables studied were gas/oil ratio (including gas from solution and free gas mixed with oil), pump compression ratio, pump stroke length, pump speed, and clearance volume between the valves at their closest approach. Results are presented for two different pumps and for oils of two viscosities. Relatively small amounts of gas entering the pump resulted in large decreases in volumetric efficiency. Under conditions where the pump was operating at reduced efficiency because of the presence of gas, it was found that variation in the clearance volume between the standing and traveling valves had a considerable effect on pump efficiency level. This effect of the valve clearance volume was found to be significantly altered by the viscosity of the oil used in the tests. The effects on pump efficiency of the other variables studied were found to be relatively small over the range of conditions utilized. INTRODUCTION The production of oil by pumping is often hampered by low volumetric efficiency. A direct increase in lifting costs results from low volumetric efficiency. An indirect increase in lifting costs, probably greater than the direct increase, results from additional wear and tear on pumping equipment and from the down-time necessary for the repairs which can be traced to low-efficiency operation. Both increases in lifting costs tend to reduce economically recoverable oil. A number of different factors can contribute to low pump efficiency. A known basic cause of low efficiency is the presence of free gas in the pumped fluid. Pump volumetric efficiency is calculated only on the basis of liquid pumped and because any free gas pumped is discounted, this volume of free gas would represent a loss of pump efficiency. However, gas also causes a reduction in pump efficiency because it is a highly compressible fluid. It is known that pumps some- times "gas lock" because of excessive gas-to-liquid ratios in the pump barrel. Little is known of the role of gas compressibility in the intermediate case where the pump is operating at low efficiency. The opinion exists, however, that oil-well pumps tend to operate at higher efficiency with long stroke lengths at low speeds, but no quantitative studies of these pumping variables have been reported. It was believed that a much better understanding of the variables which control pump volumetric efficiency could be obtained and that possibly some suggestions as to the methods for increasing efficiency might be found from a study of the operation of pumps handling gas under closely controlled conditions. Previous investigators have studied the effects on pump efficiency of such factors as oil viscosity, oil temperature, slippage of oil. past pump plungers, pump submergence, valve size and spacing, pressure above pump plunger and fluid vapor pressure. However, none of these published investigations were conducted with pumps being subjected to large amounts of gas such as might be the case in a pumping well, nor did any of the investigations study the effect of variation in stroke length or pump speed. A large-scale teat unit was therefore constructed for studying the operation of pumps handling gas and for evaluating effects of such variables as pump stroke length and pump speed. PROCEDURE AND EQUIPMENT A schematic diagram of the pump testing equipment is given in Fig. 1. A 45-ft length of 6-in. casing is mounted vertically in a 65-ft tower. Sight ports are mounted in the casing at intervals near the location of the pump intake and the liquid level in the casing. These sight ports are fitted with Lucite windows sealed by neoprene "0" rings. The Lucite windows are machined to conform to the I.D. of the casing so that no obstruction to flow is present along the casing wall. The casing is fitted with a tubing head and 2-in. tubing is hung inside the casing. Pumps are seated in a shoe attached to the 2-in. tubing. A 1-in. polish rod is attacked directly to the pump without any intervening sucker rods. The top of the polish rod is attached to the weight carrier, which contains a number of weights to be used to force the polish rod in against tubing pressure on the down-stroke. This is necessary because a long string of sucker

Jan 1, 1953

By R. B. Schluter, M. M. Fine

Development of a process for winning copper from pelletized chalcocite concentrate is underway at the Bureau of Mines, Twin Cities Metallurgy Research Center. The new route from concentrate to metal by which the Bureau seeks to eliminate matte smelting and converting includes a two-stage fluid bed treatment. In the first stage, pelletized concentrate containing 32%Cu and 7% S is first desulfurized to less than 1.0% S in an oxidizing atmosphere. In the second stage, the calcine is metallized by reduction with hydrogen. Thereafter, the reduced product plus 10% CaO is routed to a smelting furnace which separates metallic copper from the gangue. Recovery and Cu content at this point are in the 97-98% range. This product must be refined to remove sulfur and iron so the metal is suitable for making wirebar copper. An important feature of the process is fine concentrate pelletization prior to fluid-bed treatment. This permits a shorter reaction time, a decrease in dusting and easier subsequent processing. In a broad sense, sulfide copper pyrometallurgy is a batch sequence in three separate vessels, i.e., a reverberatory furnace to yield matte copper, a converter to produce blister copper and another reverberatory furnace to produce fire-refined copper. Matte-smelting has remained relatively unchanged since it became a universal practice some 50 to 60 years ago. It is now serving a wide range of smelter feed materials, but many concentrates are not immediately amenable to the process. There are abundant copper resources which lack sufficient sulfur and other elements lo sustain the full chemistry involved in matte-smelting. This necessitates adding sulfur to make the product fit the process, and usually none of the sulfur is recovered. From the standpoint of pollution alone, the development of a smelting technique for low-sulfur concentrates not requiring the addition of sulfur would be a significant gain.

Jan 1, 1970

. S. W. PARR, * Urbana, Ill. (written discussion ? ).-Multiplication of argument is unnecessary to establish the desirability of coking coals at low temperatures, that is to say, below 1200° F. The value of the semi-coke thus produced would doubtless go far toward solving the problem of smoke prevention, and suggests the possibility of the substitution of a smokeless fuel for anthracite and so-called smokeless coals. Whether such coke would have any value as metallurgical coke is a question which cannot be answered for lack of any experimental data in the use of such material. Of course interest is accentuated, at the present time, in the amount and character of the tars, which promise greatly to exceed in values the products obtainable from. the high-temperature process. The difficulties encountered in adapting the principles of low-temperature carbonization to industrial methods are well nigh insurmountable. Briefly stated, there is involved the heating of the center of a mass of non-conducting material by the external application of heat. It is a well established fact that the center of the mass of coal in a standard

Jan 11, 1918

By L. D. Mullins, E. B. Elfrink, W. L. Wahl

In the past few years several articles and papers presenting results of solution gas-drive depletion calculations have appeared in the lit-erature. Such calculations are of interest to the oil industry, for investment decisions must often be made before much is known about a reservoir. At other times, an estimate of the possible benefits to be realized from alternate production methods is desirable, and theoretical depletion calculations can serve as a floor or reference level from which to work. In any case, an estimate of ultimate oil recovery based upon engineering data is commonly required. An engineer confronted with the problem of obtaining, for a specific reservoir system, an estimate of ultimate oil recovery by solution gas-drive depletion usually will be forced to perform the calculations himself. This is despite the quantity of data in the literature. Rarely will either experience or the literature provide results from a reservoir system similar in all important respects to the one under consideration, and calculated results are not so plentiful that satisfactory interpolation procedures can be devised. Performing the calculations, however, is a tedious, time-consuming task unless an electronic computer is available, and, in practice, time and manpower are not always available for this purpose. A quick, simple, consistent method was needed for reducing the uncer- tainty in estimated oil recovery from solution gas-drive reservoirs when only minimum information about the reservoir system is available. PROCEDURE Method of Calculation The usual requisite assumptions were made so that the material balance equation could be used to calculate data for the charts. The following assumptions were made: (1) the reservoir is homogeneous and isotropic; (2) oil recovery is due entirely to solution gas drive and neither a gas cap nor a water drive nor gravity drainage is present; (3) the initial reservoir pressure is the bubble-point pressure of the reservoir fluid; (4) initial total liquid saturation is 100 per cent of pore space; (5) interstitial water saturation remains at the initial value as the reservoir pressure declines from the bubble-point pressure to atmospheric pressure; (6) equilibrium gas saturation is 5 per cent of pore space; and (7) oil and gas saturations are uniformly distributed throughout the reservoir at all times. There are no saturation gradients due to a wellbore, nor is the geometry of the reservoir system considered. The material balance equation was written in the form of a differential equation' which was integrated to determine the change in oil saturation for an assigned pressure drop. Formal integration was not possible, so recourse was made to the Runge-Kutta method' of numerical integration. All computations were performed on IBM equipment. Numerical integration yielded the change in oil saturation within the reservoir as the pressure. declined from the bubble-point pressure to atmospheric pressure. The initial oil saturation minus the change in oil saturation yielded the oil saturation at atmospheric pressure. The oil originally in place was obtained by dividing the initial oil saturation by the initial formation volume factor (differential liberation) while the oil in place at atmospheric pressure was obtained by dividing the final oil saturation by the formation volume factor at atmospheric pressure. U1timate oil recovery, expressed as a percentage of the initial oil in place, was obtained by dividing the difference between the oil initially in place and the oil in place at atmospheric pressure by the oil initially in place and multiplying by 100. PVT Data Charts were based upon 135 solutions to the material balance equation. PVT properties of the reservoir fluids were variables in this equation and had to be known as functions of pressure. The required PVT data might have been obtained from either actual reservoir fluid systems or correlated data. However, correlated PVT data were developed and employed in the calculations for the following reasons: (1) it is doubtful that 135 sets of PVT data could have been obtained for the values of variables investigated in this study, and (2) results of recovery calculations from randomly obtained PVT data could not be correlated as well as rssults from selected PVT data. The PVT data used to develop the