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By C. A. Herbert

"Haulage accidents usually are responsible for about 17 or 18 percent of all coal-mine fatalities and about 21 percent of all non-fatal coal-mine accidents. When the relatively small number of employees continuously exposed to haulage hazards is considered, it would appear that haulage is more hazardous than any other phase of coal-mine operation.Haulage accidents have increased from year to year, doubtless due to the increase in electrical haulage, and particularly to the use of larger cars, heavier locomotives, longer hauls, and greater speed. Unless very definite steps are taken to eliminate the causes of these accidents, they will continue to increase rather than be reduced, as they can and should be.Underground haulage in many of the large modern mines of today is similar in many respects to railroad practice. In recent years the railroads have made wonderful strides in reducing accidents, and instead. of being one of the most hazardous occupations, as it once was, railroading is now one of the safest. Doubtless, if thought and action, similar to that given to reducing accidents among railroad passengers and employees, were given to safety in mine haulage, under¬ground haulage accidents could be reduced in about the same ratio.Haulage accidents may be classified, according to responsibility, into two groups - those for which management is largely responsible and those for which the employee is largely to blame; there is, however, an overlapping of responsibility from one group to the other. If, therefore, haulage accidents are to be reduced, it is absolutely essential that both management and employees cooperate to this end.In the first group, for which management is largely responsible, may be included accidents due to faulty equipment, moor track, a poorly arranged system of haulage, lack of clearance or of overhead protection, and dirty roadways; even in these features, however, the employee is not without a measure of responsibility, as failure of haulage equipment possibly may be due to lack of care on his part, failure to report when equipment is out of order, or failure to do a good workmanlike job of installing or repairing or operating.To the second group of accidents for which the employee may be largely responsible, belong those caused by such careless practices as jumping on and off fast-moving trips, coupling on the ""fly"", running at excessive speeds, failure to properly block cars, and similar hazardous and unnecessary acts of omission or commission. If, however, management condones such practices, or, as in some instances, insists upon them, it must accept its share of responsibility for the accidents that inevitably result.Some of the most prolific sources of haulage accidents will be discussed briefly, together with the steps that may be taken to minimize their occurrence."

Oct 1, 1939

By Oliver C. Ralston, and others

"INTRODUCTION Investigations of the Nonmetals Division are now conducted at College Park, Md.; Tuscaloosa. Ala.; Seattle, Wash.; and. Norris, Tenn. The last of these was acquired, this year by arrangement with the Tennessee Valley Authority and is engaged in electrothermel research, using power generated by the T.V.A. and. raw materials from that region. In general, the work of the division is concerned with dressing nonmetallic minerals end utilizing the products there-from. Coal, salts, and waters are investigated, and the suitability of apparatus and equipment is studied.As the Metallurgical. Division of the Bureau of Mines makes routine tests of certain nonmetallic ores under prescribed conditions for the public if they are of general interest, the published reports of that division should be read and thus, with the reports of tile Nonmetals Division, the whole field may be covered."

Oct 1, 1939

By E. W. COCHRANE, R. HOPKINS, G

The number of completed petroleum refineries in the United States continued to decline in 1938, but the total capacity to process crude oil increased materially. This information was obtained in connection with the Bureau's annual canvass of refinery capacity as of January 1, 1939. In spite of the addition of a half dozen plants in Illinois and the inclusion in this year's list of several more "pot-stills" in Montana, the total number of plants, and inactive, declined from 551 on January 1, 1938, to 538 on January 1, 1939. was entirely in shut-down plants, as the number of operating plants rose from both active The decline 431 to 435. Yost of the plants dismantled were situated in Wyoming and Texas, parts or several from the latter being transported to Illinois. About 10 more East Texas refineries were dismantled in 1938, leaving about 15 plants in the field, only 8 of which were operating on January 1, 1939. Although the total completed capacity increased from 4,351,151 barrels on January l, 1938, to 4,508,555 barrels on January l, 1939, the operating capacity declined, and the inactive capacity increased about 50 percent, or from 380,955 to 574,770 barrels. These shifts in capacities reflect the comparative slump in the refining industry in 1938 after the prosperous year 1937. Daily average crude runs in 1938 were 3,192,000 barrels, from which it may be figured that the operating ratio for the active units was about 81 percent of crude and for all completed equipment 74 percent. The highest daily throughput in 1938 was about 3,400,000 barrels, at which time the reserve capacity represented in the active equipment was at least 500,000 barrels, in addition to about that much capacity shutdown. In an emergency, much more reliance could be placed on the reserve capacity of the active equipment, as much of the shut-down capacity is obsolete at present specifications and prices. Regarding obsolescence, the refiners reported 418,165 barrels of their idle capacity in good condition on January l, 1939 and 156,605 barrels in poor condition. However, it is probable that the former reflects an optimistic viewpoint. Refinery activity, as represented by new construction and dismantling, declined materially in 1938. The new capacity added in 1938 was 378,350 barrels compared with 394,680 barrels in 1937. Probably 1939 will see a much larger decline, as the new capacity under construction on January 1, 1939, totaled only 142,250 barrels compared with 283,020 barrels the preceding year. The capacity represented by the new plants was negligible throughout

Oct 1, 1939

By H. H. Schrenk

"One phase of the Bureau of Mines' work in the field of health and safety is the promotion of the use of safe, satisfactory, and reliable respiratory protective devices. To promote the development of such devices the Bureau has established schedules of minimum requirements for oxygen breathing apparatus3/ gas masks/, supplied-air respirators5/ (hose masks, airline respirators, and abrasive blasting helmets, hoods, or masks), and mechanical-filter respirators6/.Manufacturers of respiratory protective devices may submit their equipment to the Bureau for approval under the requirements of these schedules.As a prerequisite to such submittal, the Bureau requires a statement that the device is completely developed and of the design and material the manufacturer believes suitable for a finished marketable device; that the device has been subjected to inspections and tests such as described in the schedules, and that it met those requirements when tested by the manufacturer or his testing agency; and a. statement regarding the nature, adequacy, and continuity of control of the quality of the respirator. If the manufacturer can satisfy these requirements, and if the device, when tested by the Bureau, meets its requirements, a certificate of approval is granted by the Bureau of Mines. The approved devices bear distinguishing marks that indicate that they have been approved, the purpose for which they are approved, and the limitations of their use. If it is found at any time that approved devices purchased in the oven market and tested do not meet the requirements of the schedule, the Bureau may rescind that approval. Lists7/ of approved devices are published periodically for the convenient information of the public.Respiratory equipment may be divided into two main groups: (1). Those that afford protection by removing atmospheric contaminants and (2) those by which a respirable atmosphere from an uncontaminated source is supplied to the wearer.The devices that protect by the removal of contaminants may be divided into two subgroups: (1) Those that protect against gaseous contaminants and (2) those that protect against particulate matter. There may, of course, be combinations of these two.The devices by which a respirable atmosphere is furnished to the wearer also may be divided into two subgroups: (1) The self-contained type, by which the supply of oxygen, or material from which the oxygen can be generated is carried by the wearer, and (2) the hose type, by which air is supplied to the wearer through a hose or tube."

Sep 1, 1939

By J. F. Barkley

"The fly-ash problem of the smoke-abatement engineer - who now might well be titled, ""Smoke and Fly-Ash Abatement Engineer"" - starts with the necessity for him to know what fly ash really is, what plants really create it, and how much is being created. Fly ash in this connection may be defined as all solid particles emitted to the atmosphere as a result of the combustion of fuel.COMPOSITION OF FLY ASHMuch can be learned about fly ash by studying samples with a strong magnifying glass or, preferably, a high-power microscope. As an example, figure 1 is a photomicrograph of an underfeed-stoker fly ash weighing 23.7 pounds per cubic foot, which passed a baffle-type cinder catcher and was caught by a Cottrell precipitator. Figure 2 shows a similar fly ash made at a higher stoker rating and weighing 36.2 pounds per cubic foot. The lighter ash contains more light, unconsolidated ash than the heavier. In both instances some of the ash has been fused to a glass, as is indicated by the spherical particles resembling marbles; however, the heavier dust contains more and larger spheres. With the faster burning and higher air pressures occurring at the higher burning rates, more of the larger fused spheres reached the precipitator.Such studies of fly ash frequently make possible correct determination of its source. For example, the Supreme Court Building, one of the finest of the Federal buildings in Washington, was having considerable difficulty with fly ash from some outside plant. It was thought to come from a nearby apartment house. A fly-ash trap was installed there, and care was taken in the operation of their underfeed stokers. The fly-ash nuisance continued. Microscopic examination of the fly ash found about the building compared with samples taken from the stack of the apartment house showed to the surprise of the accusing building superintendent that the present source was elsewhere. By the same means, the source was found to be a plant about ore-half mile away."

Sep 1, 1939

By J. E. Tiffany, Z. C. Gaugler

"In presenting this list of permissible explosives and blasting devices, the Bureau of Mines desires to call attention to pages 20 and 25 outlining the conditions in use under which, and only under which, the explosive or blasting device is permissible.In view of a recent publication recounting trade practice favoring the use of a blasting device without stemming, particular emphasis is placed upon condition 4 on page 20 and condition 2 on page 25. An explosive or a blasting device enumerated in the permissible lists of this Bureau is not permissible in use unless it is properly confined with clay or other incombustible stemming.PERMISSIBLE EXPLOSIVES TESTED UNDER SCHEDULE 17CAn active list of permissible explosives was published in October 1938 as part of Bureau of Mines Report of Investigations 3421, under the title ""Active List of Permissible Explosives and. Blasting Devices Approved Prior to June 30, 1938."" This list included 191 brand names.Changes in the list that have been authorized to June 30, 1939, placed 56 additional brands of permissible explosives on the active permissible list as a result of tests, changes in brand names, or transfer from the inactive list. Fifty-seven permissible explosives were transferred from the active to the inactive list. The brand names of four explosives were rescinded curing the year. The present list contains 18G brand names. The brand names of the Permissible explosives placed on the active list are as follows:"

Sep 1, 1939

By Bernard Lewis, Guenther von Elbe

"Explosive gas mixtures are characterized by their ability to undergo a self-accelerating reaction that may culminate in ignition. In the case of methane and air there are two interdependent causes of this acceleration. First, if a sufficiently fast reaction is induced, heat may be evolved faster than it is lost to the surroundings; consequently, the temperature rises and the reaction rate increases. Second, the reaction rate is determined not only by temperature but by the concentration of reactive intermediate products if the latter increases during the course of the reaction the rate will increase. To understand the role of these active intermediates, it should be realized that molecules of methane and oxygen, per se, show little tendency to react with each other even at high temperatures.(1) If, however, free radicals like OH and CH3, are present in the mixture, the methane and oxygen are attacked in the reactions(2):In these reactions the radicals are regenerated, and thus a chain of reactions is set up by an individual radical or chain carrier which is broken only if the latter is destroyed in some process. Not all collisions of a chain carrier with CH4 or 02 result in reaction, since one requirement for a successful collision is that the colliding particles have a certain minimum energy. The percentage of collisions in which this energy condition is fulfilled increases with temperature, so that for equal chain-breaking probabilities the length of the reaction chain increases with increasing temperature. Thus, there exists an interplay of temperature and concentration of chain carriers that determines the reaction rate. To carry the rate to the stage of self-acceleration, higher temperatures are required for lower than for higher chain-carrier concentrations, other conditions being equal."

Sep 1, 1939

By George T. Faust, S. R. B. Cooke

"The Southern Experiment Station of the Bureau of Mines, United States Department of the Interior, in cooperation with the University of Alabama, is investigating the preparation of pulverized coal for fuel. In this study the relative amount of surface in various products and samples had to be assessed. Because of the familiarity with screens and because of the simplicity of using the inverse ratio of the opening for ascertaining the amount of relative surface in the respective sizes, screens down to and including 270-mesh were used. This choice was made in full cognizance of the irregularity of screens, but it seemed that if the same screens were used throughout all the tests the relative values would be satisfactory.In dealing with the subsieve sizes, pneumatic elutriation was used to make several fractions to extend the sizing analysis into the range of hypothetical screens. This kind of a sizing analysis was thought necessary because it is familiar to all operators, and, furthermore, it is amenable to several ways of plotting curves that bring out the characteristics of various coals and various methods of grinding.The method of obtaining the data from which to set up the hypothetical screen scale is the subject of this paper. It consists in determining the average projected area of the particles in the respective elutriated products. By extending the ""area method"" to sieve sizes, a factor is found that may be applied to the subsieve sizes, and thus the scale is projected in a regular manner. This method avoids contentions about specific surface and steers clear of ""average diameter"" except as material sized on screens may be said to have an average diameter."

Aug 1, 1939

By Parry. V. F., John B. Goodman

"INTRODUCTION The Denver region coal field, covering an area of approximately 7,640 square miles, extends from the Wyoming State line to the middle of El Paso County, Colo. The coal in this region is subbituminous in rank. Much of it is used as domestic fuel. During the last decade the production of coal in this field has remained fairly constant at an average of 2,600,000 tons per year. This production has come from 50 to 60 mines, 88 to 90 percent of the production being from the section of the field north of Denver.According to the Standard Specifications for Classification of Coal by Bank of the American Society for Testing Materials 4/ the coals in this region are classified in the Subbituminous B and C group. On the as—mined basis, they contain about 22 percent moisture and average 9,600 B.t.u. per pound. They are noncoking and slack to a variable extent when exposed to the weather. This is characteristic of subbituminous coals."

Aug 1, 1939

By W. W. Adams, T. D. Lawrence

"The National Safety Competition of 1938, the fourteenth of its kind conducted by the Bureau of Mines in which bronze trophies known as Sentinels of Safety are awarded to winning companies, has just been completed and the results are presented here.With 345 mines and quarries competing, more than in any previous year except 1931, the contest revealed low accident rates at many of the enrolled plants and, which is even more remarkable, it revealed 113 mines and quarries at which no lost-time accidents occurred during the contest year.The Sentinels of Safety trophies, provided by The Explosives Engineer magazine, were awarded to four underground mines, one open-pit mine, and one quarry. Each employee of the winning plant was awarded a Certificate of Honor by the Bureau of Mines in recognition of the employee's part in helping his company to win the trophy. In addition to the award of trophies, a Certificate of Honorable Mention was awarded to each of the mines and quarries in second, third, fourth, and fifth places in their respective contest groups and also to each mine and quarry that worked 30,000 or more man-hours without a lost-time accident. Ninety-two such certificates were awarded for 1938. Twenty-three other mines and quarries also operated without an accident but worked less than 30,000 man-hours, the minimum required by the contest rules for award of Certificates of Honorable Mention.Previous to 1938, five trophies were awarded annually in the National Safety Competition. For the 1938 contest a sixth trophy was provided by The Explosives Engineer so that open-pit mines and quarries, two classes of operations that previously had been included in one group in the competition, might have separate awards."

Aug 1, 1939

By C. C. Anderson, H. H. Hinson, H. J. Snhroeder

"INTRODUCTION The Eunice field is one of a group in southeastern New Mexico producing oil and gas from so-called limestone-type reservoirs in which the productive strata are dolomite or dolomitic limestone ordinarily, wells in reservoirs of this type show wide differences in their productive characteristics, indicating erratic variations in porosity and permeability. Often there is a large difference in total footage of actual ""pay"" penetrated in neighboring wells and the vertical distribution of the ""pay"" within the productive strata varies. In the Eunice field there are few easily recognizable geologic markers to indicate true structural conditions of the oil-productive section, due to horizontal and vertical gradation in chemical compositions and lithologic characteristics of the strata. Geologic markers are found some distance above the oil-producing zones in this field and consequently they indicate only the general structure. Furthermore, no direct relation has been found between the general structure and the accumulation of oil within the reservoir.Many problems in well-completion and production practice have been met in the Eunice field because of erratic variations in porosity, permeability, in vertical distribution of ""pays,"" and the apparent departure from ordinarily accepted relations of oil accumulation to structure. A detailed study of the position and characteristics of the oil- and gas-producing zones aids production procedure. The methods employed in studying the Eunice field, discussed in this paper, may be applicable to other limestone-type reservoirs."

Jul 1, 1939

By B. W. Gandrud, G. D. Coe

"INTRODUCTION The Bureau of Mines, United States Department of the Interior, with the cooperation of the University of Alabama and coal producers of Alabama, is making a series of washability studies to obtain technically and commercially important data from the productive coal beds of the State. Based on the system followed in these studies, this report consists of screen-sizing and sink-and-float data on the America and Pratt beds at Gorgas, Ala.SAMPLING AT THE MINESAlthough operations were discontinued in 1929, the accessible openings of the old Gorgas mines of the Southeastern Fuel Co. made possible the taking of samples from the America bed at three openings and from the Pratt bed at two openings. A sample was taken from the America bed at the Klondyke opening; a second was taken about 1 rile south of the Klondyke at the Musgrove America opening, and a third sample was taken about 1-1/2 miles south of the Musgrove-America at the Cricket Lodge opening. A sample was taken from the Pratt bed at Musgrove-Pratt No. 1, which is about 3/4 mile east of Musgrove-America, and a second sample was taken at Musgrove-Pratt No. 2, which is about 3/4 mile west of Musgrove-America. The samples ranged in weight from 1/2 ton to 1 ton and were equivalent to approximately a 2-ton sample from each bed. Figure 1 shows sections of the beds at the places sampled.In addition to the samples for washability study, a seam sample for analysis was taken at each of the places sampled. So as to give a representative seam sample for each of the two beds, these samples were combined in the laboratory in proportion to the thickness of the bed at the places sampled."

Jul 1, 1939

By H. J. Hager, B. W. Gandrud, G. D. Coe

"INTRODUCTION The reduction of washery losses of marketable coal is a phase of coal preparation important to many of the Alabama coal producers. The problem has wide scope, and this report deals with but one of its several aspects. The investigation on which this report is based was made by the Southern Experiment Station of the Bureau of Mines with the cooperation of the Alabama By-products Corporation and the University of Alabama. The Alabama Byproducts Corporation provided samples of table middlings from its Colta washery on the Mary Lee bed at Flat Creek, Ala.PRACTICE AT THE COLTA WASHYAt Colta run-of-mine coal is crushed in a hammer mill in closed circuit with 5/16-inch square-mesh vibrating screens and tabled without classification on eight rectangular-deck wet tables. The coal is more friable than the bone normally present, and hence the bone is concentrated in the coarser sizes. An unclassified feed of this character can not be tabled with high efficiency to low ash content because of the sizing action of a concentrating table, which is such that when the tables are adjusted to exclude the coarse bone from the washed coal, a large amount of fine coal is lost in the middlings. At the time this investigation was undertaken there was no market outlet for middlings, with the result that middling products had to be discarded with the refuse."

May 1, 1939

By H. S. Auvil, J. T. McCartney, J. D. Davis

"INTRODUCTION It is now generally recognized that the small-scale laboratory dilatometer method of test does not give results of much utility in predicting the expansion (or contraction) of a coal in a coke oven. The carbonizing conditions in the laboratory test differ radically from those in the oven; in this test, the charge is heated through the coking range of temperature as a whole, whereas in the oven, coking proceeds by layers parallel to the oven walls as each succeeding portion of the charge goes through the plastic range of temperature and coke formation sets in. The paths of the gases and vapors and the pressures set up are different in the two methods. Furthermore, the rate of heating in the test usually is much more rapid than in the oven. H. Koppers 5/ was perhaps the first to adopt apparatus and procedure whereby the layer coking of the coke oven could be simulated closely however, the heating progressed from one side of the charge only; later he experimented with a small coke oven with a movable wall heated from both sides. It is not clear how well the results in the later oven correlated with those of the earlier small test oven, but in a comparatively recent Koppers publication a modification of the original small test oven heated from one side is recommended 6/ Altieri 7/ was perhaps the first to experiment with the Koppers type small test oven in the United States and Brown- has tested a large variety of coals in a rectangular test oven of his own design heated from the sole or floor. Subcommittee XV of American Society for Testing Materials Committee D-5 is now making a study of the various methods proposed for determination of expanding and plastic properties of coal with a view to standardization. 9/"

May 1, 1939

By C. E. Arrington, A. C. Rice

"Part 1. REDUCTION AND USE OF OXIDANTSSUMMARYA study has been made of the volumetric determination of molybdenum by reduction in the Jones reductor, receiving the reduced solution in a mixture of ferric alum and phosphoric acid, and titrating with standard oxidizing agents. In addition to potassium permanganate, which has long been utilized for this titration, potassium dichromate and ceric sulphate have been found to be applicable. The latter oxidants have been found to be especially useful in the form of dilute solutions for the determination of small amounts of molybdenum. The tests revealed that certain internal indicators give excellent results in these titrations.Reason for These ExperimentsThe following study was initiated with the hope of providing the mining and metallurgical industries with an accurate and rapid technical method for the determination of molybdenum in such low-grade materials as ores, rocks, tailings, steels, and alloys containing less than 0.3 percent molybdenum. Although the experimental work was designed with this purpose in mind, many of the results are applicable to material containing a higher percentage of molybdenum.While the Bureau of Mines had an experiment station in Colorado, considerable analytical work was done on what were then (up to about 1923) classed as rare metals. One of these was molybdenum; and in Bulletin 212, Bonardi's (1) 3/ 60-page chapter covered all methods for the analysis of molybdenum."

Apr 1, 1939

By R. G. Knickerbocker, A. L. Fox, J. Koster, P. R. Perry

"During the past several years, alunite from the Marysvale (Utah) region has been the subject of investigation by the Electrometallurgical Section of the Bureau of Mines. The nature and occurrence of this mineral, with considerable data on the Utah deposits, together with a number of results of preliminary experiments, have been given in a previous report. 6/ The geology of the Marysvale region has been reviewed recently. 7/The present paper reports the results obtained by a method involving the sintering of alunite with boric acid and subsequent treatment of the sinter to produce alumina and potassium sulphate.The preliminary work just mentioned had given indications of the separation of sulphate salts high in potassium from fusions of alunite with borax glass.During the course of further work along those lines, fusions of boric acid and alunite were tried. No separation of salts was obtained, but it was observed that rather complete removal of so3 from the alunite occurred and that the sinter could be leached with water to give a solution contain¬ing most of the potash and a residue containing most of the alumina. The reaction that takes place can probably be written 8/:"

Mar 1, 1939

By M. W. Strong

The technique of handling drilling muds varies somewhat, partly because of personal factors but mainly because of differences in formation, the type of problems, and the general drilling conditions in different localities. The much greater depths to which bore holes are now carried have made necessary closer attention to and great modifications of all aspects of drilling-mud technique. Increased depth means smaller hole, smaller drill pipe, smaller clearances, higher pumping pressures, higher differential pressures between shows and the mud column, less accurate control of the weight of the mud column, delayed receipt of formation data, and poorer samples. It means longer delays and greater hazards in rectifying mistakes or dealing with accidental occurrences. Equipment on a larger scale is necessary and more pains must be taken with layout. Lastly, the budget costs of raw materials have risen to high figures and economy of time and of direct monetary expenditure have come to mean much more than formerly. A mud laboratory is now part of the essential establishment of a modern oil field and to it current problems can be submitted for the most thorough investigation. The detailed chemical properties of all materials purchased or quarried have to be investigated. Detailed data on the physical properties have to be ascertained and research on improvement of material and its most efficient use has to be carried out. In this paper will be discussed the main mud problems of Iran, some of which are peculiar to local conditions while others are of the general type common to all workers in this subject. Underground Conditions In deep wells in Iran the normal overburden may consist of: (1) up to several thousand feet of marls with interbedded sandstones and limestones of varying porosity and permeability; (2) beneath this a chemical series of rock salt and anhydrites, containing various marls and thin limestones,

Jan 1, 1939

By E. V. Foran

Among the many newer disclosures that have accompanied the petroleum industry's progressively deeper exploratory drilling is the increased frequency with which the operators are encountering reservoirs of which the products at the time of discovery exist wholly or predominantly in the gas phase. The popular term "distillate pool" is most often used within the industry when referring to this type of reservoir, and in this paper the term is used in that sense. These pools have been observed in many different surroundings. In some places the entire reservoir is filled with the wet gas containing its water-white condensible products in the gas phase but apparently with no dark oil or other hydrocarbon liquids in the reservoir. The 8200-ft. horizon in the Big Lake field in West Texas is a good example of this type. At other places the wet, or distillate-bearing, gas may form a large gas cap directly overlying and in contact with an extensive reserve of dark oil. Oklahoma City, Kettleman Hills, the 8500-ft. horizon in the Big Lake field, and many others are examples of this type. There are also many places in which the wet distillate-bearing gas fills nearly the entire reservoir space, while the dark oil occupies only a narrow, bandlike zone, which marks the boundary of the reservoir along its lowest productive contour. The heavier components of these deep pool gases are generally water white in color, a large portion of which are condensible in a conventional oil and gas separator, when operated under pressures of the order of 400 to 800 Ib. per sq. in. Although the water-white products recovered in the separator sometimes have end points of 650" F. and higher on standard Engler distillation, they occur only in the gas phase in the reservoir. It is entirely possible that even some small amounts of dark colored reservoir components may occur in the gas phase when the temperature is 300" F. and pressures exceed 6000 Ib. per sq. in. Close approaches to these conditions have been encountered in the deepest producing wells. The condensible content of the deep reservoir gases of the many pools that have been tested or produced to date shows a wide variation in both condensible content, per 1000 cu. ft. of gas, and physical character.

Jan 1, 1939

By Howard C. Pyle, John E Sherborne

Core analysis is a recent development in the field of petroleum technology. The earliest work on this subject was done in connection with evaluating and planning secondary oil recovery by water-flooding. Present-day analysis of sands of flush fields requires new and independent interpretations of the data provided by cored material. Particular attention is being paid to the development of rapid, routine methods for measuring physical characteristics of sandstone, such as permeability, porosity and grain size, as well as the sand's fluid content. Permeability may be defined as the fluid-passing capacity of a rock. For a sandstone to be permeable it must be possible to pass a measurable quantity of fluid through the material in a finite period of time. The common unit of permeability is the darcy, which may be defined as the rate of viscous flow, in milliliters per second, of a fluid of one centipoise viscosity through a porous medium having a cross section of one square centimeter, under a pressure gradient of one atmosphere (76.0 cm. Hg) per centimeter.' For convenience the subunit millidarcy, or one-thousandth darcy, is often used. Porosity is defined as the fluid-containing capacity of a rock and is usually expressed as a percentage ratio of the total pore volume to the rock or bulk volume. Since measurement of only the effective or communicating pore volume is often made, porosities are distinguished as total or effective.2,3 Net effective porosity is defined as the net pore volume available for oil and gas. Oil and water content of sand is measured and expressed either as the percentage saturation of the total pores or of the bulk rock. The oil content may also be expressed as the percentage saturation of the net effective pores. In connection with water-flooding, methods of core analysis were developed to furnish data that could be used in determining the quantity of recoverable oil14-6 and the probable rates at which various sands or divisions of a sand open to the wells would take water or produce oil. In flush fields, the analytical data are used to predict the productivity of a cored interval. They indicate the presence of oil, gas and water and may

Jan 1, 1939

By J. J. Jakosky

The fundamental hydrodynamic principles governing the production of oil from wells have been carefully studied and evaluated by many investigators. These prior studies are quite complete and cover virtually the entire field of oil production and recovery.' One of the most important measurements in production studies is that of the bottom-hole pressure at various rates of production.2 It is the purpose of this paper to outline the technique and economics of fluid-level measurements as applied to pumping wells and to review briefly other methods for obtaining bottom-hole data. The applications of bottom-hole pressure or fluid-level measurements are based on simple hydrodynamic principles. Under equilibrium conditions, pbh = hd + pg + pch [1] when pbk = bottom-hole pressure, Ib. per sq. in. absolute, h = height of fluid in well, ft., d = average fluid density, Ib. per sq. in. per foot, p, = weight of section of gas column 1 in, square from fluid level to casinghead, Pch = casinghead pressure, Ib. per sq. in. absolute. In words, equation 1 states that the bottom-hole pressure is equal to the weight hd of the column of fluid plus the weight of the column of gas between the fluid and the casinghead plus the casinghead pressure. At moderate rates of flow, the rate of production is approximatcly proportional to the difference between the reservoir, or static bottom-hole. pressure and the flowing or producing pressure; i.e.: Q = c(pr - pbh) [2] pr = the reservoir pressure, c = the constant of proportionality. However, at production rates approaching zero and also at high rates the proportionality may break down. By combining equations 1 and 2 the

Jan 1, 1939