Search Documents

Illustrated guidebooks treating in a popular descriptive way of the geology and other features of the Western United States have been issued by the U. S. Geological Survey. They will be of much interest to mem¬bers in connection with the Arizona Meeting of the Institute and espe¬cially the guidebook of the Santa Fe Route, with side trips to the Grand Canyon, containing as it does relief maps, topographical and geological maps, covering the entire route of the railroad, illustrations from photo¬graphs and other interesting descriptions of this great country. The method of treatment is adapted to the lay-reader, although it includes much valuable and interesting technical information concerning the geographical and other features. The books are well indexed. These volumes sell for 50 c. each and may be obtained from the Superintendent of Documents, Washington, D. C. These guidebooks originally sold for $1 each, but the reprint edition has been reduced to 50 c. A list of the different guidebooks follows: Bulletin 611. Guidebook of the Western United States, Part A, The Northern Pacific Route, with a Side Trip to Yellowstone Park, by M. R. Campbell, and others. 1915. 212 pages, 27 route maps, 27 plates, 39 text figures.

Jan 6, 1916

By George W. Orton

i\- number of investigations have established that tungsten monocarbide (WC) forms throughout a wide range of temperatures (800° to 2200°C), but the di-tungsten carbide (W2C) forms only at the high end of this temperature range.1"7 In addition the decomposition of WC into WzC and C at elevated temperatures has been observed.8"10

Jan 1, 1964

By W. B. Mather

R. G. Wuerker (University of Illinois, Urbana)—Mr. Mather is to be congratulated for stressing the most urgent need for a program of testing the physical properties of rocks, as they are encountered by the petroleum engineers on their drilling jobs and by the miners on their excavating, roof control and mineral preparation tasks. Another valuable source of information is the Handbook of Physical Constants.22 It stresses the physicist's approach rather than the engineer's procedure. The study of hardness, and rock hardness in particular, is beset with many difficulties. There is no satisfactory definition of hardness yet, and the term hardness is used to describe a number of quite dif- ferent properties. Hardness tests are grouped into static and dynamic determinations. They should be expressed with reference to the mechanical action of the applied force, like indentation hardness, scratch hardness, abrasion hardness, rebound hardness. A discussion of all these various hardness tests and of the special difficulties encountered in hardness testing of such heterogeneous material as rocks is given in the U. S. Bureau of Mines' standard proposal. The more critical student may be referred to the book by D. Landau: Hardness, which is in my opinion the best existing treatise on this subject.

Jan 1, 1952

By David B. Reger

The year 1935 was mostly quiet in West Virginia, and devoted to routine drilling in old pools and extensions. A notable exception to this general rule, however, was the further development and proving of a field of gas discovered in 1930 in the deep Oriskany sand (L. Dev.) in Kanawha County, as later discussed. No new pools of oil were found and little or no attempt was made to search for them. No new pools of gas were recorded but various extensions of old pools were made. There were no new pipe line extensions of consequence, either for oil or gas. Operating technology was much the same as in recent years, there having been some further advances in repressuring oil wells and in the use of acid for treating small wells in calcareous formations, and some change in the technique of shooting gas wells. Financially, there has been a full market for all crude oil produced and a fair market for gas. There have been occasional transfers of producing oil or gas properties, mainly between established companies. Most of the attempts made to finance mergers and new developments have failed largely because of difficulties encountered under the Federal securities act. This situation has prevented the normal turnover of properties by small operators who frequently desire to sell partly developed interests and then step out into new ventures. New Development In 1935 the State issued 569 permits for drilling and records the same number of completions. One trade journal records 533 completions and another 483. A running record kept by the writer accounts for 713 completions, with 156 oil wells, 417 gas wells and 140 dry holes (Table 3). Some of these completions may be old wells drilled to deeper sands. Some, apparently, have been drilled without legal permit. Extensions of Producing Areas Ritchie County has again led all others in new drilling, with 137 completions as compared to 74 in Calhoun and 61 in Cabell. This Ritchie County drilling was done mainly to extend or further develop old pools

Jan 1, 1936

By David B. Reger

The year 1935 was mostly quiet in West Virginia, and devoted to routine drilling in old pools and extensions. A notable exception to this general rule, however, was the further development and proving of a field of gas discovered in 1930 in the deep Oriskany sand (L. Dev.) in Kanawha County, as later discussed. No new pools of oil were found and little or no attempt was made to search for them. No new pools of gas were recorded but various extensions of old pools were made. There were no new pipe line extensions of consequence, either for oil or gas. Operating technology was much the same as in recent years, there having been some further advances in repressuring oil wells and in the use of acid for treating small wells in calcareous formations, and some change in the technique of shooting gas wells. Financially, there has been a full market for all crude oil produced and a fair market for gas. There have been occasional transfers of producing oil or gas properties, mainly between established companies. Most of the attempts made to finance mergers and new developments have failed largely because of difficulties encountered under the Federal securities act. This situation has prevented the normal turnover of properties by small operators who frequently desire to sell partly developed interests and then step out into new ventures. New Development In 1935 the State issued 569 permits for drilling and records the same number of completions. One trade journal records 533 completions and another 483. A running record kept by the writer accounts for 713 completions, with 156 oil wells, 417 gas wells and 140 dry holes (Table 3). Some of these completions may be old wells drilled to deeper sands. Some, apparently, have been drilled without legal permit. Extensions of Producing Areas Ritchie County has again led all others in new drilling, with 137 completions as compared to 74 in Calhoun and 61 in Cabell. This Ritchie County drilling was done mainly to extend or further develop old pools

Jan 1, 1936

By S. N. Dixon

Sampling and assaying procedures were developed to obtain unbiased and reasonably accurate Au grade estimates in drill samples fm a coarse gold deposit. Gold grade comparisons were made by assaying 3 (1 assay ton) splits from each drill interval, then processing the entire reject thru a pilot plant for a blocked out zone. The result comparing the assay splits to the pilot plant results gave a ratio of 1 to 1.07. Another technique was developed to detect drill samples which has a coarse gold content by monitoring the varience. Testwork could be done on a 1 kg sample to improve the accuracy of the grade estimation if the variance was high for a drill interval.

Jan 1, 1984

By Thomas R. Couzens

This chapter covers certain aspects of open pit production planning based on experience, pointing out approaches to planning that may help produce a realistic picture for evaluation and operation The subjects discussed are roads, preproduction stripping, dump planning, dewatering, the relationship of production planning to equipment selection, and computer methods for the short-range or operational pit planning process Actual determination of ore limits, pit design, and production schedules are covered in other chapters This discussion is somewhat general. Specific problems that occur in mine planning are extremely varied, and it is not possible to cover many of them in a chapter, therefore, only some of the principles that are important in the approach to open pit production planning problems will be discussed.

Jan 1, 1979

By H. W. Young

Development of high-tension outdoor substations during the past few years has been due primarily to economic reasons. The demand for power in small communities could not be met with the conventional and Fig. 1.—33,000-VOLT step-up outdoor air-break switch and substation installation outside of a powerhouse generating at 2300 volts stepping up to 33,000. Twenty-one coal mines are supplied from lines leading from this installation. comparatively expensive indoor types unless the rate for service was materially increased. To prove that the problems lncident to development have been solved successfully, it is only necessary to point to the wide adoption of outdoor substations by utility companies. Passing at once to the question as to whether outdoor substations are applicable to

Jan 1, 1920

By John V. Beall

TOO early spring may be the explanation for the poor turnout of mining and metallurgical engineer candidates at a large New York guidance conference, but it would be wiser to take a more serious view of this occurrence. Held a few weeks ago, the meeting was preceded by weeks of preparation and publicity in which many engineering societies participated. The meeting was the First Greater New York University downtown campus for splitting up anticipated to draw about 20,000 high school students from the New York area and environs. Seven of the theatres in the Paramount chain were avail- able to hold the audience for a panel program on career opportunities which was to be televised and piped into the theatres. Following the morning theatre session, students were to adjourn to the New York University downtown campus for splitting up into workshop sessions devoted to seventeen different branches-of the profession.

Jan 5, 1953

By S. A. Braley

DRAINAGE water from coal mines is probably the most serious water pollution problem today, varying in importance according to location of the mines and geological structure. Drainage may be either acid or alkaline in character. Acid discharge, the most severely detrimental to a stream, is caused by natural oxidation of the sulfuritic material (FeS2) in the strata associated with the coal seam. Since the acid is the result of a natural reaction the acid water differs because it does not cease with abandonment of the mining operations. There is no known economical method of neutralizing acid mine water or any practical method to prevent oxidation of exposed pyrite. Since production of acid from a mine does not stop when mining stops, the total quantity produced depends entirely upon the excavated areas. The increasing volume of acid water in many mines has greatly increased operating costs. Pumping is expensive and acid mine waters are destructive of all equipment, especially metals in pumps and piping, and necessitate the use of corrosion-resistant materials. Discharge of the acid mine drainage into streams neutralizes their normal alkalinity, causes them to become acid, and produces an environment unfavorable for aquatic life and unsuited for industrial or domestic use without costly treatment.

Jan 1, 1957

W. P. PUTNAM,. Detroit, Mich.-There is one company that is heating these tubes in an upright position by passing electrical energy directly through the tube itself. The lower connection is attached to an indicator, which shows the point at which the steel passes through the critical range At that point the clamps are released and the tube is dropped into a well of oil. This method simplifies the heat treatment of tubes in long lengths. H. J. FRENCH.-I am not entirely familiar with. the method outlined, but it appears to have one serious disadvantage; that is, the length of tubing that is directly connected with the electrical contacts is wasted and must be cut off due to either heavy oxidation or burning. That is a serious difficulty, if true in all cases, and cannot be overcome, inas-much as it is very difficult to draw long tubes of thin wall. Having once obtained a lot of tubes, to cut, say 14 ft. in length, there is often little excess metal available to discard. Am I correct concerning the burning or heavy oxidation of the metal where it comes in contact with the tube.

Jan 12, 1919

THE CHAIRMAN (J. W. RICHARDS, South Bethlehem, Pa.)-The first point on which I wish to speak is that sufficient attention has not been given to the quality of the ores, in estimating the reserves. I made this same criticism of the work on the iron-ore resources of the world issued by

Jan 12, 1918

By R. Maddin, S. K. Tung

SUCCESS of the dislocation theory in formulating the transitional lattice theory proposed by Har-greaves and Hill in 1929' is well established for low angle grain boundaries. The theoretical work of Burgersa and Read and Shockley,3 together with the experimental observations of Aust and Chalmers4 and Parker and colleagues,6 leaves little doubt as to the structure of grain boundaries with differences of orientations up to between 15" and 20". Beyond these angles, the structure of the boundary is not so clear, and is still a matter for conjecture. There have been notable experiments devised from which the data could be used to calculate energetics for possible arrangements of atoms in forming a large angle boundary.6 Most of these experiments deal with diffusion through and along the grain boundary. The recent work of Rhines and Cochart7 and Rhines, Bond, and Kissel18 was concerned with the relative movement of grains in aluminum bicrystals under constant tensile loads with their boundaries aligned at 45 " to the tension axis. The gliding along the grain boundary was cyclic and began after an incubation period. The velocity of gliding increased with the sum of the angular difference, 8, between the operative slip direction in the conjugate crystals and the angular difference between the active slip planes as measured between their traces upon the grain boundary. The initial gliding rate varied with temperature, and the logarithm of the average gliding taken over a considerable period was a linear function of the reciprocal of the absolute temperature: the slope gave an activation energy of 11,000 ±1,000 cal per mole. Since the rate of grain boundary shear is sensitive to the misorientation of the grains themselves, as shown by several workers,7,8 it is suggested that further work of this type might be fruitful in adding information regarding the behavior of boundaries under stress. The techniques devised by Chalmers" added impetus to the facility for observing grain boundary behavior, in that they provided a simple means for producing bicrystals of predetermined orientation so that the angle of the boundary could be controlled,

Jan 1, 1958

By Henry Howe

W. E. RUDER, Schenectady, N. Y.-In 1913 I presented a paper before this society on Grain Growth, and at that time it seemed to me that the only explanation for grain growth was that of critical strain. I do not think I published the photographs at the time, but I made some experiments on the effect of stretching sheets of metal. This allowed for fairly accurate determinations of the amount of cold deformation, At the time I worked-with silicon steel because one could see the change in grain growth with the naked eye. I stretched about 10-samples from 0.5 per cent. to 10 per cent., and, after heating to 1,050° C., I found that the maximum grain growth occurred at about 2 ½ per cent. cold deformation. This I designated "the critical strain" for maximum grain growth. About a year ago I talked with Prof. Jeffries, who explained to me his ideas of grain growth. It occurred to me that it would be a very easy thing to check the strain hypothesis against the strain and temperature hypothesis, if we took a certain number of these strips, strained exactly alike and heated to different temperatures; in that case the maximum grain growth ought to appear at a different percentage of deformation for each temperature. These experiments showed that there was, as Mr. Jeffries shows in his present paper, a decrease in germinative temperature with increased cold deformation. The samples were stretched from ½ to 8 per cent. and heated for 10 hr. in hydrogen. Samples were introduced into a furnace previously heated to temperature. A maximum grain growth was obtained at 5 per cent. deformation, when heated to 750° C.; at 2 ½ per cent. when heated to 800' C.; at 1 1/4 per cent., if heated at 950°C.; and at 5/8 per cent.. when heated at 1,100° C. This shows very clearly that the germinative temperature decreases with the increase in cold deformation. The growth was very much more marked, however, at the high temperature, i.e., the grain grew more rapidly and attained a much larger size than at lower temperature. In considering the photographs (Fig. A) those along the lateral edges should be ignored because.

Jan 4, 1917

By A. U. Seybolt, V. A. Phillips

Binary iron alloys containing 1 pct of Al, Cr, Mn, Mo, Si, Ti, or V, and 0.4 pct C, 1 pct Cr steels with and without 1.2 pct A1 or 2.0 pct Ti additions, were ion-nilrided at 550° to 600° in N-H mixtures. Nitriding increased the inicrohardne ss of all the binary alloys except those containing manganese or molybdenutn, and also hardened the heat-treated steels if aluminum or titanium urns present. Transmission electron microscopy revealed particle formation in all casts where hardening occurred. Electron diffraction gare positive identifications for ALN, CrN, and a, Si3N4 in the binary alloys, and AlN and CrN in the aluminum- cold chromium-bearing steels, respectil&apos;uly. Cubic VN with a, = 4.13A was tentatively identified. Particles, apparently of CrN, also formed in the base steel but did not increase the hardness very much. Chromium and vanadium formed nitride platelets on {001}° matrix planes, while titanium gave clusters <15A diam. Aluminum nitride precipitated at grain and subgrain boundaries, and within the grains. Silicon gave profuse precipitates of several Morphologies at grain boundaries and cubical particles within the grains. No effect of the alloy carbides on nitride precipitation was observed in the heat-treated steels. THE nitriding of steel has been a well-established commercial process for about 40 years, but in spite of this comparatively long period of use there have been few studies aimed at understanding the process. Most studies, like the early but very competent work of Jones and organ&apos; and nones.&apos; were concerned with establishing the pertinent engineering variables of steel composition, gas composition, temperature, and time. As far as the present authors are aware, there have been no studies of the composition, size, shape, or distribution of the nitrides formed in the nitriding of steel. Noren and Kindbom3 did, however, examine a few nitrided steels by surface replica electron microscopy, and were able to show the presence of car-bonitrides and AlN and TiN nitrides. pitsch4,5 and Hrivnak6 examined nitrided pure iron by transmission electron microscopy. Baird7 found manganese nitrides in Fe-1.6 pct Mn when nitrided at 650°C, using the same technique. In the present work, emphasis was placed on transmission electron microscopy because of its inherently better resolution, using principally binary alloys of iron containing 1 pct of alloying element. In addition, a few simple 0.4 pct C steel compositions were examined to investigate possible carbonitride formation. It was not anticipated that all of the added elements would form nitrides under the conditions used, but it was considered desirable to obtain direct experimental evidence on this point. It would be considerably easier to ascertain the presence of alloy nitrides by examining appropriate binary alloys in preference to relatively complex steels. The work reported here could have been done using orthodox ammonia-nitriding procedures, but an operating ion-nitriding equipment was available, and was therefore used for specimen preparation. EXPERIMENTAL DETAILS 1) Materials. Binary alloys were made up from vacuum-melted electrolytic iron with 1 wt pct additions of Cr, Ti, V, Al, Mn, Mo, and Si of about 99.9 pct purity. In addition, three steels were similarly made up—a basis steel with 1 wt pct Cr and 0.4 wt pct C and two steels with further additions of 1.2 wt pct A1 or 2.0 wt pct Ti, respectively. The materials were vacuum-melted and cast as 11-lb heats into tapered square molds of about 2 by 2 in. average cross section. The castings were forged and hot-rolled to 11/4 in. rounds. Discs of 4 in. thickness by about 1 in. diam were machined from the rods. Some of these discs were hot-forged and hot-rolled to about 0.020 in. thick, sand-blasted, and then cold-rolled to about 0.003 in. thick. At this point, the surface was cleaned by light etching with HC1, then washed, dried, and vapor-degreased prior to nitriding. 2) Ion-Nitriding Procedure. The type of ion-nitriding equipment used here is similar to that described by Jones and Martin.8 Briefly, a mixture of nitrogen and hydrogen at 5 mm total pressure is placed in a vacuum chamber with a dc potential of 450 to 500 v applied between the work (cathode) and the grounded metal vacuum enclosure (anode). Nitrogen ions are accelerated to the work where a thin layer of Fe4N forms on the surface and thus sets up a nitrogen concentration gradient. This causes nitrogen atoms to diffuse into the surface layers of the alloy forming a finely divided dispersion of alloy nitrides, causing hardening of the surface. In the work to be reported here. the nitriding was carried out at 550° to 600°C to be consistent with commercial nitriding practice. The temperatures cited are those measured by a thermocouple located under a platform on which the work was sitting. Except where otherwise stated, the mixture used in nitriding the binary alloys contained -2.0 pct N, balance hydrogen. The nitrogen concentration in the nitriding gas mixture used for the binary alloys was purposely kept lower than normally used in nitriding steels. 10 to 20 pct, in order to minimize Fe4N formation. In this way only the alloy nitrides would be present as a second phase. However, in the case of steels which would contain a- carbide phase along with as

Jan 1, 1969

By A. F. Bertuzzi, M. R. Tek, F. H. Poettmann

A method is presented for predicting pressure drop for two-phase fluid flow in horizontal pipes. A set of 267 experimental measurements randomly sampled from approximately 1,000 measurements from various literature sources was used. Pressure gradients calculated by the procedure developed and compared with the experimental values showed a bias of +0.82 per cent and a standard deviation of 20.8 per cent. The advantatges of this method over other available methods of predicting two-phase flow pressure drop are (a) its comparative simplicity of application, (b) its relative independence of flow patterns, (c) its accuracy, which on the basis of a statistical evaluation predicts pressure drop closer than other available methods, and, (d) its ability to satisfactorily correlate laboratory data from various sources while the correlations from these sources do not appear to agree with one another. The method has been reduced to a simplified graphical procedure, suitable for field use. A two-phase f factor is defined and correlated with parameters involving the flowing gas-liquid mass ratio, a Reynolds number for the gas phase, and a Reynolds number for the liquid phase. The choice of parameters allows the correlation to reduce to the usual f factor plot for the limiting conditions of (111 gas or all liquid. INTRODUCTION The mechanics and characteristics of two-phase flow systems have been of interest throughout the industry for some time. In numerous engineering installations such as pipe lines, chemical reactors, and heat exchangers, two-phase flow conditions are of every day occurrence. In oil production operations it has been desirable, in some cases, to consider transporting gas and oil together in a common pipe from oil field to process plant. The trend toward centrally located stock tank batteries in oil fields has resulted in longer gathering pipelines in which more than one fluid phase is flowing. The increase in the producing capacity of oil wells due to new production tech- niques has created the need for review and re-design of many surface gathering lines for properly handling the increased production. Optimum pipe size for the situations described above has become an important factor. The problem which is of interest here involves the ability to predict the relationship between pressure drop, fluid properties, fluid rates, pipe diameter, and pipe length. Although the literature1,5,10,13,18,19 contains various articles dealing with specific cases of the problem, Lock-hart and Martinelli17 proposed the most general solution. Their method has been later modified by Baker:1 Alves2 demonstrated that different flow patterns are possible for a flow mechanism defined by Martinelli such as gas turbulent, liquid turbulent. Baker explained deviations experienced with Martinelli&apos;s correlations on the basis that different flow patterns could exist for the same flow mechanism. Using Martinelli&apos;s method of correlatioil, Baker correlated data for each flow pattern for the turbulent-turbulent flow mechanism. Bergelin and Gazley6,7 presented a correlation for predicting gas phase

Jan 1, 1957

By Walter Remmers

THE fact that gray iron increases in volume, cracks and distorts upon repeated heating and cooling is rather common knowledge. In ingot molds, Diesel engine pistons, carburizing boxes, continuous furnace parts, grate bars, stoker parts, and all castings that are subjected repeatedly to high and low temperatures, the phenomenon of growth presents a vital problem. Ingot molds distort and produce cracks which result in seams or laps and later appear as defects in the finished product. The heads of Diesel pistons frequently fail by cracking in a stellar shape. This is attributed usually to the result of permanent growth. Distortion and change of dimension of furnace parts frequently renders them entirely unusuable. In chain grate stokers, mechanical difficulties frequently are caused by the growth of the links. In proper operation these links should never attain a temperature sufficiently high to start growth; nevertheless, some have grown 1/8 in. on an 8-in. length when improperly operated. Even though the phenomenon is generally known there still exists a deficiency in the explanation of the mechanism of this growth. The field of investigators of this subject has a decided variation in opinion concerning the causes. The problem is of sufficient importance therefore to warrant further consideration.

Jan 1, 1930

By R. M. Stewart, C. W. MacQueen

Anaconda&apos;s Berkeley pit at Butte produces 34,000 tpd of ore averaging 0.8 pct copper. Two-and-one-half tons of waste is stripped per ton of ore, approximately 40,000 tpd by the company and an added 45,000 tons by the F&S Contracting Co. The company truck fleet consists of 24 Euclid and 18 Mack 34-ton, rear-dump diesel trucks.

Jan 7, 1961

Recent start-up of a new 3450 t/d (3800 stpd) copper-zinc concentrator complex in northern Manitoba, Canada, is expected to open new reserves and dramatically cut transportation costs for Hudson Bay Mining and Smelting Co.&apos;s Snow Lake operations. The new $C33-million mill is located in Stall Lake, Manitoba, and includes a new crushing and grinding facility and two flotation circuits for the production of 23-25% copper and 55% zinc concentrates. A small amount of lead concentrate will also be recovered. The plant will produce some 145 000 t/y (160,000 stpy) of concentrates, to be shipped by rail to the firm&apos;s Flin Flon copper smelter and zinc refinery complex, located 177 km (110 miles) to the west on the Saskatchewan-Manitoba border.

Jan 9, 1979

By J. M. De La Garza Cárdenas

The total production of oil in Mexico in 1942 was 34,715,547 bbl.; that is, 8,179,254 bbl. less than the amount produced in 1941. The daily average for 1942 was 95,111 bbl., while that for 1941 was I17,520 barrels. The reduction of 22,409 bbl. per day in production was due to a decrease in exports because of the scarcity of tankers. This reduction has affected principally the Northern and Southern districts of the Tampico area; in December the Northern district (Panuco) was producing less than zoo0 bbl. per day with 445 wells shut down and the Southern district (GolJen Lane) less than $000 bbl. per day with 140 wells shut down. Drilling.—During the year 14 wells were drilled in Mexico, of which five were productive. Seven dry holes were drilled in Ebano, Tampico Northern district, in search for new producing fractures; plans are being made to explore this area by means of resistivity measurements. Three producing wells were completed in Poza Rica. Drilling in this important field will continue during 1943 to determine its extension to the west. In the Isthmus of Tehuantepec no wells were completed. Two gas wells were completed in northeastern Mexico. Wildcats.-—Two wildcat wells were completed during the year, to test the extension of the Golden Lane to the south; both were unproductive. In the Isthmus a deeper sand was found in the El Plan field* This discovery has made an important increase in the reserves in this field and will allow an increase in the production of the area during 1943. In December, three exploration wells were being drilled, two in the Tampico area and one in the Isthmus. Operating Technology.— Satisfactory progress has been made in Mexico in the application of petroleum engineering to the development and operation of the oil fields. Mud control is now an established practice and has lessened the number of fishing jobs and has allowed more open hole to be carried than formerly was possible. During 1942 the first effective use was made of determinations of bottom-hole pressure, and other modern production practices such as gun-perforating and squeeze-cementing are being introduced. Plans for 1943 The oil production during 1943 is expected to be slightly larger than that of 1942, especially if tankers are available for exporting crude and refined products. The Government proposes to increase exploration and drilling activities to increase the reserves and potential production of the country; about 50 wells will be drilled during the year, including wildcat wells in northeastern Mexico, Tampico and Isthmus areas and exploitation wells in the Ebano-Panuco, Poza Rica, El Plan and Cuichapa fields. Acknowledgment Mr. A. Barnetche, of the Production Department, "Petr6leos Mexicanos," assisted the writer in the preparation of the statistical data.

Jan 1, 1943