Search Documents

By J. P. Smith

DURING the winter of 1946 to 1947 potash operations in Germany, France and Spain were visited by the author. The U. S. Department of Commerce, through its Field Intelligence Agency Technical, sponsored the inspection of German properties by representatives of the American Potash Industry. Vast deposits of potash salts occur in the above-mentioned countries, and the production and marketing of these salts are important in their respective economies. Germany An area of some ten thousand square miles of north central Germany is underlain by lenses of potash salts interbedded with greater thicknesses of sodium chloride or common salt. These salt measures are relict deposits from the evaporation of an arm of the Zechstein (Permian) Sea which formerly covered northern Europe. During the peak year of 1940, Germany produced salts containing 1,860,000 tons of K,O and, next to coal, potash is its most important mineral raw material. The German deposits are found in the synclinal areas flanking the Flechtingen, Hartz Mountain and Thuringian uplifts, and, to the north they lie beneath the plains of Hannover. The regional dip of the salt measures is to the north, hence, lenses of potash found at depths of 500 to 1000 m* in the Two general depositional provinces of potash concentrations are recognized: (1) the main basin, and (2) the subsidiary basin. The main basin embraces the producing districts of Stassfurt, Sud Hartz, Halle, and Hannover-Braunschweig. From J. P. SMITH, Member AIME, is Clzief Geologist, U. S. Potash Co., Carlsbad, New Mexico. New York Meeting, February 1948. TP 2621 H. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received May 26, 1948. 40 to 45 pct of the German production comes from this basin. The Werra-Fulda district, producer of 50 pct or more of the German potash, lies in the subsidiary basin. Salt Stratigraphy: Five commercial potash zones or beds are recognized. The three beds present in the main basin are: The Stassfurt bed that occurs near the top of the older salt, and the Ronnenberg and Riedel beds in the younger salt occurring 200 to 300 m, respectively, above the Stassfurt bed. The Stassfurt bed is found over the entire main basin, while the Ronnenberg and Riedel are restricted to the Hannover area. Two potash beds occur in the Werra basin. These are the Thuringian, or lower bed and the Hessen or upper potash bed that occurs 60 m above. These beds lie 210 and 150 m, respectively, below the position of the Stassfurt bed, and are restricted to the Werra basin. The upper bed is 2.5 to 11.5 m in thickness, and the principal ores are hartsalz with varying thicknesses of carnallite. The lower bed averages 3 m in thickness, and contains hartsalz. The upper bed is presently being mined, and the

Jan 1, 1951

By J. P. Smith

DURING the winter of 1946 to 1947 potash operations in Germany, France and Spain were visited by the author. The U. S. Department of Commerce, through its Field Intelligence Agency Technical, sponsored the inspection of German properties by representatives of the American Potash Industry. Vast deposits of potash salts occur in the above-mentioned countries, and the production and marketing of these salts are important in their respective economies. Germany An area of some ten thousand square miles of north central Germany is underlain by lenses of potash salts interbedded with greater thicknesses of sodium chloride or common salt. These salt measures are relict deposits from the evaporation of an arm of the Zechstein (Permian) Sea which formerly covered northern Europe. During the peak year of 1940, Germany produced salts containing 1,860,000 tons of K,O and, next to coal, potash is its most important mineral raw material. The German deposits are found in the synclinal areas flanking the Flechtingen, Hartz Mountain and Thuringian uplifts, and, to the north they lie beneath the plains of Hannover. The regional dip of the salt measures is to the north, hence, lenses of potash found at depths of 500 to 1000 m* in the Two general depositional provinces of potash concentrations are recognized: (1) the main basin, and (2) the subsidiary basin. The main basin embraces the producing districts of Stassfurt, Sud Hartz, Halle, and Hannover-Braunschweig. From J. P. SMITH, Member AIME, is Clzief Geologist, U. S. Potash Co., Carlsbad, New Mexico. New York Meeting, February 1948. TP 2621 H. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received May 26, 1948. 40 to 45 pct of the German production comes from this basin. The Werra-Fulda district, producer of 50 pct or more of the German potash, lies in the subsidiary basin. Salt Stratigraphy: Five commercial potash zones or beds are recognized. The three beds present in the main basin are: The Stassfurt bed that occurs near the top of the older salt, and the Ronnenberg and Riedel beds in the younger salt occurring 200 to 300 m, respectively, above the Stassfurt bed. The Stassfurt bed is found over the entire main basin, while the Ronnenberg and Riedel are restricted to the Hannover area. Two potash beds occur in the Werra basin. These are the Thuringian, or lower bed and the Hessen or upper potash bed that occurs 60 m above. These beds lie 210 and 150 m, respectively, below the position of the Stassfurt bed, and are restricted to the Werra basin. The upper bed is 2.5 to 11.5 m in thickness, and the principal ores are hartsalz with varying thicknesses of carnallite. The lower bed averages 3 m in thickness, and contains hartsalz. The upper bed is presently being mined, and the

Jan 1, 1951

By Harvey S. Mudd

WHEN talking about Europe it is well to endeavor to keep politics and economics apart but they have become so intermingled in recent years that the discussion of one topic inevitably leads to the other. Economic influences formerly prevailed over politics but today national and international economies are governed by political forces. Commerce in raw materials, food, and manufactured products is now so restricted by governmental controls that the capacity of the world to produce and to consume, to exchange goods and to pay for them, cannot be gauged by the past or predicted by a multitude of experts. In prewar days there were some yardsticks but today there are none. Thus it is hazardous to make forecasts, for in all fields of human effort the world has been cast upon an uncharted sea.

Jan 1, 1947

By Y. C. Liu, G. A. Alers

The anisotropy of Young's modules has been measured in a series of Cu-Zn alloys containing from 1 to 28 wt pct Zn and cold-rolled to 97.5 pct reduction in thickness. These modulus data show a transition in texture as a function of zinc content. In alloys containing 3 pct Zn or less, the texture is essentially that of copper. A transition is clearly seen to develop in 5 and 8 pct Zn alloys, and to have been completed in a 12 pct Zn alloy. Increasing the proportion of zinc to 28 pct does not produce any further changes in texture. The ease and clarity with which this texture transition can be seen in the modulus data is in great contrast with the inccertainty in the visual detertiination of the range of texture transition from a series of pole figures. It is also shown that the rolling texture of the high zinc content alloys cannot be a one-COIIIponenl texture, characterized by the (110)(112) ideal orientations, as usually assumed. A second, quite important component must also be present. Furthermore, the present data are inconsistent with matrix orientations on which the "oriented growth" hypothesis of the Formation of recrystallization textures is based. THE rolling textures of binary fcc alloy systems have generally been considered to lie between two terminal textures. One of these terminal textures is the copper type and the other is the 70:30 brass type. Alloys of intermediate solute content exhibit a texture which is said to be a transition between the two terminal textures. On the basis of efforts to correlate rolling and recrystallization textures, two concepts have been advanced in the literature on the nature of these transition textures. One school1 suggests that the addition of alloying elements, e.g., zinc, causes a gradual rotation about one of the (111) poles from the (358)( 523) ideal orientation of the copper-type rolling texture to the terminal {1 10)( 112) ideal orientation used to describe the rolling texture of 70:30 brass. This concept is depicted in Fig. 1 with the angle of rotation corresponding approximately to the zinc content and is designated here as the "rotational concept", since the ideal orientation of the transition textures varies continuously with alloy content. The other concept,' the "mixture concept", suggests that the copper-type rolling texture is a two-component texture. {358) (523) and {110)(112). The addition of alloying elements affects only quantitatively the relative amounts of these two components—a decrease in the amount of material in the {385}(523) orientation and an increase of that in the {110)(112) orientation with increasing solute content. An experimental distinction between these two concepts is essential to a better understanding of both the mechanism of formation of rolling textures and the subsequent formation of recrystailization textures in fcc metals. Because of the lack of resolution inherent in pole figures, it has not been possible to differentiate between the two concepts on the basis of this data. Both concepts, in fact, make use of the same set of pole figures but interpret them in a manner acco-rding to the view held.'" Experimental results obtained from inverse pole figures or selected-area electron diffraction3j4 simply -yield more refined pole figures but do not eliminate the ambiguity of interpretation. Quantitative measurement of an entirely different, orientation-dependent property must thus be considered

Jan 1, 1967

By Jasper L. Stuckey

PYROPHYLLITE, first identified as soapstone,1 later as agalmatolite,2 and finally as pyrophyllite,3 has been known to occur in North Carolina for more than 130 years and has been produced intermittently in commercial amounts for the past 100 years. Pyrophyllite mining, however, has become a major industry in North Carolina only during the past 25 years. North Carolina and California are the chief producing states. Current annual production averages 125,000 tons, of which slightly more than 90 pct comes from North Carolina. Distribution and Geologic Setting: All known pyrophyllite deposits in North Carolina are associated with rocks of the Carolina Slate Belt,4 which is composed of a vast series of metamorphosed volcanic and sedimentary materials, occurring as two zones extending in a northeast-southwest direction across the state. The larger of these zones, lying in the central Piedmont region, varies from 8 to 50 miles wide. The smaller zone lies along the eastern edge of the Piedmont region and is partly covered by coastal plain sediments.

Jan 1, 1958

By F. W. Jessen, C. C. Patton

Adsorbed films were formed on polished stainless steel specimens from dilute benzene solutions of two crude oil distillation residua. Although the two residua were extremely dissimilar in composition, contact angle measurements showed that the two films increased the wettability of the steel specimens to oil by equal amounts. Furthermore, the wettability of the films was essentially unaffected by the desorption techniques used. Paraffin deposits were formed from heptane-wax solutions on the same stainless steel specimens. These deposits definitely adhered to the surface. Presence of an adsorbed crude oil film on the metal surface increased its free surface energy and resulted in increased deposition of paraffin. The addition to the heptane - wax solution of small amounts of the same distillation residua that were used to form the adsorbed films resulted in decreased cohesive strength in the deposits formed, which resulted in decreased deposition. The presence of a crude oil fraction both in the solution and as a preadsorbed film eliminated the adherence of a deposit of any kind. A mechanism of deposition is proposed which explains the results obtained. INTRODUCTION The natural formation of any predominantly organic accumulation in oilwell tubing, surface flow lines or other production and storage facilities is called a paraffin deposit. These deposits restrict the production of crude oil, causing a substantial increase in production costs because of decreased flow capacity, expense for periodic deposit removal and unproductive downtime. The conditions under which such deposits form, their physical characteristics and the nature and severity of the problem created are extremely varied. Over the past several years, much progress has been made in developing and utilizing methods to remove accumulated paraffin deposition. However, like so many other problems, the basic stumbling block appears to be a lack of understanding of the fundamental mechanism involved in the formation of such deposits. Crude petroleum is known to contain considerable quantities of polar, surface active substances which Doddl has shown to be present at the oil-water interface. Denekas, Mattax and Davis2 observed that the wettability of reservoir rocks was drastically altered by exposure to crude oil fractions; and Zisman, et a1.3 showed that the nature of the compounds adsorbed on a surface would determine its wettability characteristics. Cole and Jessen4 and Ehrig5showed that surface wettability can have a profound effect on the magnitude of paraffin deposition, and Parks6 demonstrated chat the presence of certain adsorbed films on a metal surface would reduce the adherence of paraffin to that surface. Zisman7 has since advanced the theory that the conditions for adhesion are the same as for wetting. Therefore, it was felt that there was adequate evidence to support the supposition that adsorption of compounds from a crude oil might play an important part in paraffin deposition. ADSORPTION-WETTABILITY EXPERIMENTS Initial experiments were conducted to determine the effects of adsorption from solution of crude oil residua on the wettability of a polished stainless steel surface. Distillation residua with initial atmospheric boiling points of 700F were used in preference to the whole crudes in order to concentrate on the molecular weight range of interest, and to eliminate the possibility of composition change due to evaporation of the light ends. Also, these high boiling materials would be expected to be adsorbed from the whole oil in preference to similar compounds of lower molecular weight.

Jan 1, 1966

By Carel Robinson

THE little coal mine at Otsego, in the Winding Gulf field of southern West Virginia was dying. In the history of coal mining thousands of mines have been successful at first, but usually a change occurred and profits ceased. Often be change was so gradual and extended over such a length of time that the fundamental causes did not stand out in sharp relief and their significance was not realized. Studies often reveal that the cause for failure was in the arteries that connect the producing places with the mine entrance. Profits continued so long as the working places were close to the tipple and while the thrill of newness aid ease of access resulted in effective supervision from day to day. The air- way and haulageway, the wire line and manway, may have been sufficient when the distance from the entrance was a few hundred feet, but were inadequate when this was extended for thousands of feet.

Jan 1, 1937

By Edward H. Robie

SEPTEMBER usually being a fine month for motoring, we set out with our better half at the end of August in our Studebaker for points West. A combined business trip and vacation. The first night found us 392 miles away, at the Statler Hotel in Buffalo, and the next morning we revisited Niagara Falls for the first time in some forty years. The cataracts were as impressive as ever and certainly worth a day of any vacationist's time, instead of the half hour we could spare before going on to Chicago. The Centennial of Engineering, the hundredth anniversary of the founding of the ASCE, no doubt attracted the greatest gathering of engineers in history but still the attendance was disappointing to most of the forty or fifty societies that participated. Perhaps the time-the two weeks following Labor Day-was unfavorable. Few could afford to spend ten days away from home and business at that time of the year. Fall meetings of the AIME normally attract far more than the 300 that registered in Chicago. The technical program, however, was excellent, especially that arranged by the Minerals Beneficiation and Industrial Minerals Divs. The mineral industry papers of a more general nature that were presented as a part of the Centennial program on Monday and Tuesday of the following week were of high quality and offered by top names but had a meager audience. Undoubtedly the celebration brought engineers and engineering to the attention of millions of people. The pageant at the Museum of Science and Industry proved continuously interesting, showing the progress of engineering following the first use of fire. The show continued for many weeks. A special stamp was issued by the Government, which engineers might well use on their Christmas cards or other mail this year. After six days in Chicago we set out north, first visiting Fairbanks Morse in Beloit and Allis-Chalmers in Milwaukee. Will Mitchell's Basic Industries Research Laboratory is doing interesting work and being installed in more comfortable quarters. The next day at Ishpeming, C. W. Allen arranged for luncheon with a local group of AIME members and we then looked over the new surface plant of the Mather B mine, a model of modern functional design. Then on to a small dinner meeting at Calumet following cocktails at Endicott Lovell's attractive summer home on the lake at Point Mills. The new Memorial Union Bldg. at Houghton, where we were domiciled for the night through the courtesy of Roy Drier, is a beautiful modern addition to the college, a model of its kind.

Jan 1, 1952

Willet G. Miller, Toronto, Canada (communication to the Secretary): In his interesting paper Mr. Lindgren says: " As to ultimate results, it would seem as if we should be justified in concluding, with Prof. Suess, that the gold-supply of the world will gradually decrease if no further important improvements are made in the processes for the extraction of this metal; but regarding events so far distant no predictions may safely be made." It seems to the writer that no very important improvements require to be made in order at least to keep up the present production for many years to come. In many parts of the world there are large deposits of auriferous material which can be worked if present conditions are slightly changed. In the territory occupied by the Archean protaxis of the Province of

Jan 1, 1903

By C. E. Melbye

A serious problem confronted the city of Gunnison early in 1958 in that, for a few months during each spring runoff, the water supply derived from the Gunnison River became polluted to an unsafe point. The city management had the choice of building a new filter plant to replace the old unworkable one or drilling wells to develop a ground water supply. The cost of a new filter plant was estimated at $180,000 compared to $50,000 for 6 wells, pumps, and additional water lines, hence their decision to attempt the development of sufficient ground water. Six wells at 300 gpm per well were estimated as necessary to handle the peak usage of 1800 gpm, compared to only 600 gpm winter usage. Although the water table is only about 7 feet below the surface, existing private wells drilled at random locations were producing much less than 300 gpm. The problem was to find sufficient quantities from about 6 wells. Since the presence of an ancient bedrock channel was suspected, which would be expected to localize greater quantities of water, the city of Gunnison authorized a resistivity survey to investigate bedrock topography below unconsolidated gravels. Survey results were highly satisfactory and led to the preparation of a fairly detailed bedrock contour map, Fig. 1. This map was used in selection of all well sites. The city of Gunnison is situated in a flat, broad, Quaternary gravel-filled valley (terrain dips south at 20 feet per mile) at the junction of the Gunnison River and Tomichi Creek. The valley, about 2-4 miles wide, is bordered by hills of Tertiary volcanics to the northwest, Cretaceous and Jurassic sediments to the north and northeast, and pre-Cambrian granite and gneiss to the south. One previous deep test well at the west end of the city hit pre-Cambrian granite at 496 feet, which, allowing for 40 feet of surface gravels, makes the older sedimentary section 456 feet thick. This section is probably all Jurassic Morrison formation, consisting of the Saltwash sandstone overlain by the much thicker section of Brushy Basin shales and mudstones. According to the driller's logs, each well was bottomed in what is believed to be Brushy Basin shale. FIELD PROCEDURE A standard Gish-Rooney type of resistivity apparatus was employed, which used 45-volt dry batteries as a direct-current power source. Applied voltages could be selected from 45 volts to a 270-volt maximum. Copper-coated steel stakes were employed as current electrodes and porous porcelain pots as potential electrodes to avoid possible polarization effects with direct current. The expanding Wenner electrode configuration was utilized for this investigation and measurements were made at 20 40, 60, 80, and 100-foot spacings,

Jan 1, 1961

By Murray F. Hawkins

One problem of reservoir engineering is the early estimation of the size of newly discovered reservoirs. Often these reservoirs are the expansion type in which sizeable pressure drops occur incident to the production of small fractions of the oil reserve, above the bubble point, and a material balance equation may be solved to find the reserve. The early form of this equation' considered only the compressibility of the oil. Later Hall2 showed that the compressible nature of the formation rock is a significant factor in production above the bubble point, and he presented a new equation which includes a formation (rock) compressibility term. This note presents a further extension of the material balance equation as applied to volumetric, unsat-urated reservoirs above the bubble point by including a term for the presence and compressible nature of the interstitial water. DERIVATION OF EQUATION During a decline in average reservoir pressure, ?p ?p, — p1 the initial reservoir volume V,, will decrease to some value V, due to the reduction in pore volume as a result of a decline in the hydrostatic pressure within the formation, and v, = V,, [l — cr ?p]......(1) The formation compressibility c, is expressed in terms of change in pore volume per unit pore volume per psi. Simultaneously the connate water within the formation expands from an original volume V,, = S,V,, to a new volume V,, V, = s,v,, [I + c,npl.....(2) The difference [Vp — V,] is the hydrocarbon pore volume at pressure p and may be equated to the volume of the remaining oil, or [N — N,] B, = V,,, [I - C~A;] - S,.Vpi [l + cwnjl.........(3) But the initial oil in place in terms of the initial reservoir volume, connate water, and formation volume factor is Ilividing Equation 3 by Equation 4 eliminates V,, to give,

Jan 1, 1956

By Arthur L. Crawford

PLAGER gold is perhaps the most difficult of the common mineral deposits to evaluate. Not only are the erratic pay streaks a source of never-ending uncertainty, but the spotty distribution of the gold in iso¬lated nuggets is a perpetual source of error and disappointment to the sampler. Experienced engineers have long realized this difficulty and have been wary in predicting assay values except in the most general terms, and then only after extensive and usually expensive sampling. During the past year I have had the opportunity of checking a number of gold placers, and from the results obtained I believe that the microscope may be employed to advantage in placer sampling.

Jan 1, 1933

Discussion of the paper of E: D. Gardner, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 91, July, 1914, pp. 1467 to 1471. H. V. WINCHELL, Minneapolis, Minn.-There are two questions I should like to ask: First, does the Department still adhere to the decision made in the East Tintic case? Second, does the Department require placer ground to he of such value that, in the opinion of the Forest Service employees, it will pay to work, before admitting the location to be valid? T. C. HOYT,* Ogden, Utah.-With reference to the first question: the Department does not hold to that decision, as it was reconsidered by the Secretary Of the Interior, and the Department is governed by the decision of the Secretary Of the Interior, on those points always. The Department of Agriculture makes no decision as to what constitutes a sufficient discovery. The mineral examiners simply report their findings and Opinions. These are transmitted to the chief of the field division of the General Land Office, who in turn transmits the reports to the Commissioner Of the General Land Office, who decides whether the report raises an issue requiring a hearing. If a hearing is ordered, expert testimony is given on the question of the discovery, as well as the evidence of practical people who operate in the vicinity of the claim in question. As to the extent of placer values considered sufficient to justify a location, my answer will need a little amplification. I couldn't answer it directly for the reason that sometimes people resort to placer claim location as a means of acquiring land for Other purposes than placer mining, which makes it absolutely necessary that the government give close attention to the question of whether good faith has been shown, as it is the evidences of good faith that largely determine whether a report adverse to a claim shall be made. That is a difficult point to cover sometimes. For instance, in the region I have recently visited there are some 17 miles of a valley, from ¼ to ¾ mile in width, all covered by placer locations. It is valuable stock-grazing land, and is stocked at the present time. It also contains a stand of timber, and is on the watershed of an important stream-important from the fact that it furnishes the water supply to government storage reservoirs, and to pending reclamation and Carey Act projects. In this case the placer claims will not be disturbed as mere locations. They will simply remain there, and there will be no action with reference to them until the claimant asks for patent or, before patent, begins to denude that watershed and remove that timber. Then the government would direct that the mineral experts go on to the ground, examine it, prospect it, and submit their report, with a view to seeing if

Jan 11, 1914

Jan 1, 1971

By AIME AIME

COAL preparation will be the main topic discussed at the first fall meeting of the Coal Division at Pittsburgh, Sept. 11, 12 and 13, though valuation, mergers, safety, stream pollution and other topics will not' be neglected. It is particularly appropriate that the great changes taking place in preparing coal for the market should be discussed at length where in the plants of the Pittsburgh Coal Co. and others the opportunity is afforded to see on a large scale just what is being accomplished. In wartime, the United States broke all records in coal production, but, as the late Franklin K. Lane pointed out, every fifth car shipped consisted of dirt. Obviously that constituted a big bur- den on industry and, in the remaking of the business which is now taking place both in the anthracite and bituminous fields, clean coal has properly enough be- come a watchward. Central coal-cleaning plants are being erected as a part answer to the puzzled inquiry of those familiar with metal mining as to why miners of coal have so long been content with what are relatively small units of production. Gradually big collieries comparable in tonnage output to the biggest copper mines are being built, and excellent examples are to be seen near Pittsburgh. Even the age-long tradition of the coal operator in favor of the single shift is

Jan 1, 1930

By L. R. Raymond

With the trend toward deeper and consequently hotter holes, measurements of drilling mud properties at atmospheric temperatures are becoming increasingly inadequate.' Both the prediction and control of down-hole mud properties depend in part upon our knowledge of temperatures in the wellbore. Consequently, a better understanding of factors that affect temperatures during circulation and trips could improve drilling operations. It was toward the goal of obtaining this understanding that this study was directed. Other investigators2 have studied the response of fluid temperature in the borehole during trips. However, all of these studies have used an assumed formation temperature profile at the conclusion of circulation and have provided no means to calculate this profile directly. In this study, the formation profile during circulation was calculated. Other investiga-tors3-5 have also studied bottom-hole temperature during circulation. However, they have developed neither general techniques for calculating the entire temperature profile in the system nor generalized methods for predicting bottom-hole fluid temperatures during circulation. Such techniques and methods have been developed and are discussed briefly in the following pages. Temperature Behavior During Circulation Circulation of fluid during the drilling operation is represented schematically in Fig. 1. The process of circulation has three distinct phases: (1) fluid enters the drill pipe at the surface and passes down the drill pipe; (2) fluid exits the drill pipe through the bit and enters the annulus at the bottom; and (3) fluid passes up the annulus and exits the annulus at the surface. To simulate the thermal behavior of the fluid in the system, each of the phases of circulation must be described mathematically. In Phase 1, the fluid enters the drill pipe at a specified temperature, TDo. As the fluid passes down the pipe, its temperature is determined by the rate of heat convection down the drill pipe, the rate of heat exchange between the drill pipe and the annulus, and time. Phase 2 of the circulating process merely requires that the fluid temperature at the exit of the drill pipe be the same as the fluid temperature at the entrance of the annulus; i.e., TD(L,t) = TA(L,l). Thus in Phase 3, the fluid enters the annulus at TD(L, t). As the fluid flows up the annulus, its temperature is determined by the rate of heat convection up the annulus, the rate of heat exchange between the annulus and the drill pipe, the rate of heat exchange between the formation adjacent to the annulus and the fluid in the annulus, and time. These rates of heat exchange and the time dependency of mud temperature are described by well known heat-flow equation.6 Consequently, as shown in the Appendix, the temperature profiles in the drill pipe, annulus, and formation can be obtained by solving Eqs. 1 through

Jan 1, 1970

By H. H. Pentz

This paper gives the derivation of a practical formula for the calculation of slopes in seismic reflection prospecting. The derived formula is an approximation and can be used where the slope of the reflecting horizon is less than 250 ft. per 1000 and the depth to the reflecting horizon is greater than 2500 ft. The slope of sediments in oil regions is generally considerably less than 250 ft. per 1000. This is particularly true of the Gulf Coast, with the exception of the salt domes, which usually have the sediments at a greater slope than 260 ft. per 1000. Derivation In Fig. 1, o represents the image of the shot point a. Then the length of the path acb is equal to ob and ae'd is equal to od. In the triangle aob, p is equal to ob, x is equal to , and c is equal to ao. The angle u is the apparent dip of the reflecting horizon. Angle oab is equal to (90" - u). The quantity m is the slope of a line tangent to the curve, defined by equation 1, at the point (p, x). The quantity m' is the slope of the line tangent to the curve at the point (p', 2').

Jan 1, 1940

By H. H. Pentz

This paper gives the derivation of a practical formula for the calculation of slopes in seismic reflection prospecting. The derived formula is an approximation and can be used where the slope of the reflecting horizon is less than 250 ft. per 1000 and the depth to the reflecting horizon is greater than 2500 ft. The slope of sediments in oil regions is generally considerably less than 250 ft. per 1000. This is particularly true of the Gulf Coast, with the exception of the salt domes, which usually have the sediments at a greater slope than 260 ft. per 1000. Derivation In Fig. 1, o represents the image of the shot point a. Then the length of the path acb is equal to ob and ae'd is equal to od. In the triangle aob, p is equal to ob, x is equal to , and c is equal to ao. The angle u is the apparent dip of the reflecting horizon. Angle oab is equal to (90" - u). The quantity m is the slope of a line tangent to the curve, defined by equation 1, at the point (p, x). The quantity m' is the slope of the line tangent to the curve at the point (p', 2').

Jan 1, 1940

Alexander N. Winchell, Butte, Mont. (communication to the Secretary): Mr. Spurr calls attention to the fact that an ore-deposit may be due to a succession of concentrations at different geological epochs. He cites an example of such a condition on Napoleon creek, a branch of Forty-Mile creek, Alaska. It will perhaps be of interest to call attention to another example of the same general character, not so remotely situated. The example referred to is located on Pole creek, a tributary of Cherry creek, in the extreme northeastern part of Madison county, Montana. An excellent geological map of this region is to be found in the Three Forks folio (No. 24) of the United States Geological Survey. According to this map, Pole creek, in its upper course, occupies the contact between the " Flathead " formation, which Peale correlates with the Middle and Lower Cambrian, and an area of gneisses and schists supposed

Jan 1, 1903

The Library of the above-named Societies is open from 9 A.M. to 9 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M.. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information-will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining-maps, and to furnish general information as to the geology and mineral resources of all countries: All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute. can be of service to the Library by forwarding copies of mining-reports, maps privately issued, and similar material, which will he classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will be welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 5, 1913