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By C. W. Binckley, F. R. Burgess, E. R. Haymaker

A method of establishing stabilized back-pressure curves for gas wells producing from formations of extremely low permeability is presented. Actual well performance under many different operating conditions is shown by the stabilized back-pressure curve. By use of the method. it is possible to conduct back-pressure tests with a critical-flow prover on wells that stabilize slowly, and save approximately 88% of the gas ordinarily vented to obtain satisfactory test data, with a great reduction in time required for testing. INTRODUCTION The reasons for establishing dependable back-pressure curves on gas wells have been pointed out by previous publications. The publication most referred to. of course, is the United States Bureau of Mines Monograph 7, titled "Back-Pressure Data on Natural Gas Wells and Their Application to Production Practices". The technique generally established therein has been accepted and used by many engineers; and, when proper tests are conducted, the results can be used for the analysis and solution of several practical problems concerning field operation and development. Even where formations of low specific permeability are encountered, the determination of a well's actual performance by the back-pressure test method permits the engineer to analyze many problems in individual well operation and also to predict necessary future field development. Such problems as the determination of the ability of a well to produce into a pipe line at a predetermined line pressure, the design of gas gathering systems and meter settings, and the determination of the time and the number of wells required to be drilled to meet future market obligations, can be solved, in part., by the use of a reliable back-~ressure curve. In addition, the computed well delivery rates determined by data from backpressure tests ordered by state regtilatory bodies, when compared with the true back-Pressure curve, permit the operator to ascertain whether such data represent unstable or relatively stabilized delivery rates for given pressure conditions of the well. The technique of back-pressure testing, as described in this report, was developed by Phillips Petroleum Company engineers from data obtained during a testing program that started in 1944 and has been continued to date. Three hundred and eleven back-pressure tests were conducted on 299 wells located in the southern part of the Hugoton Field. The gas-bearing zone is composed of several dolomitic formations of the Permian Age; the important ones are the Herington, Upper Krider, Lower Krider, and Winfield. The average bottom-hole temperature is approximately 91 °F.. and the initial wellhead shut-in pressures range from 400 to 440 psig. The spacing pattern is 640 acres per well with each well located near the center of the section. The range of back-pressure potentials on wells tested was from 500 to 23,000 Mcfd. All gas wells were acidized, and the quantity of acid used, expressed in 1574 hydrocloric acid, varied from 12,000 to 22,000 gallons per well. The quantity and concentration of each treatment depended on the stage, the formation being treated, and experience gained from previously completed wells. The gas in the Hugoton Feld is a "dry" gas. It has a gasoline content of approximately 0.25 gallons per thousand cubic feet, as determined by charcoal test, and its specific gravity averages about 0.71 as compared to air (air = 1.00 at 60°F.). Of the wells tested, 71 were completed with 7" casing, 3 with 9 5/8" casing, and 1 with 6%" casing set on top of the upper producing formation with the well bore through the gas bearing formations being open hole. Two hundred and twenty-four were completed with 5 1/2'' O.D. casing set through the gas bearing formations and perforated. For the purpose of establishing reliable back-pressure curves in the area, Phillips Petroleum Company personnel has computed data on the basis of 24-hour flows per point. Early in the program, many tests were actually permitted to flow 24 hours to obtain data for each plotting point, at great expense in man power and time. Presently, however, such tests have been replaced by tests of short duration flows which can be made to effect results that correspond to the tests obtained by flows of much longer duration. METHOD When a gas well producing from a reservoir of low permeability is opened for production through a constant size orifice, both the rate of flow and working pressure decline. first at a high rate and later at a lower rate until after several hours the decline becomes difficult to ascertain. In this paper the rae of flow and working pressure are considered to be stabilized when it becomes difficult to observe changes in working pressure during a period of three hours by the use of a deadweight pressure gage. Stalibization of pressure in the literal sense is never obtained in a producing gas well. In formations of low permeability. such as those in the Hugo-ton Field, most wellhead working pressures approach stabilization closely enough to be used satisfactorily in the determination of a back-Pressure potential curve after flow periods of 24 hours. We shall therefore describe the backpressure curve calculated from ohserved rates of flow and working pressure at the end of 24-hour flow periods.

Jan 1, 1949

By John Lamb

"The French Mine (formerly the Oregon) is 4 miles by road south of the Nickel Plate Mine. It lies on the steep eastern slope of the Similkameen River valley at elevation 4,000 feet, between Cahill and Winters Creeks.The property was discovered in .1901 and bought 4 years later by Messrs. French and Deardorf. It was developed in a modest way by the owners and by several companies until 1947, without success. The spectacular showings of bornite and chalcopyrite in the outcrop drew attention to its possibilities for copper rather than gold. Diamond drilling by the owners in 1947 yielded several high-grade gold intersections and created new interest. In 1949 the property was purchased by Kelowna Mines Hedley Limited. Exploration drilling and geological mapping outlined sufficient ore to commence production in 1950. Except for a few months each winter the operation has been continuous, and to the end of 1954 had produced almost 30,000 tons of high grade ore. The ore is crushed at the mine and hauled 8 miles by truck to the Company mill at Hedley, where it is treated together with the ore from Nickel Plate.Regional GeologyThe country rock consists of brown tuff, flows, limestone, and cherty formations belonging to the Nicola group (Rice 1947) of Triassic age. West of and just below the mine is a large mass of granodiorite which is part of the same body that underlies Nickel Plate Mountain. Bedding attitudes in the mine area are locally complicated, but dips are generally less than 45 degrees. To the south and below the mine the beds stand almost vertical, continuing downward with this attitude for 2,000 feet to Winters Creek. The main granodiorite contact is also steep, conforming to the sedimentary formations, whereas northward towards Nickel Plate it dips gently to the northwest, slightly flattter than the thick westerly dipping pile of sediments above it. The interpretation of this structure by Billingsley (1936) is that the French mine lies near the crest of the large northeasterly trending asymmetrical anticline which contains in its gently dipping western limb the Nickel Plate orebodies. The granodiorite body conforming roughly to this shape seems to occupy the core of the anticline. Sill-like prongs of granodiorite extend upward to the east from the main mass, outcropping over wide areas at the head of Winters Creek (Figure 1). There is a possibility that overthrusting from the west, similar to that on Nickel Plate Mountain, occurs not far below the French mine.An interesting feature of the granodiorite-sediment contact is that where it dips gently westward no alteration exists in the sediments, but where it has a steep front pronounced heat effects are indicated by the presence of a thousand-foot-wide zone of reddish garnet skarn."

Jan 1, 1949

By Albert E. Long

During the summer and fall of 1948 the Bureau of Mines, in cooperation with the U. S. Geological Survey, conducted 6xperiments in diamond core drilling in the Phosphoria formation in southeastern Idaho and southwestern Wyoming. Nearly all of the diamond core drilling in the Phosphoria formation has been done by mining companies interested in finding and developing phosphate-bearing beds amenable to stripping. The recovery of sludge; and enough core (usually 30 to 60 percent) to identify certain marker beds produced by current drilling practices meets both the primary requirement of mining companies in determining depth of overburden and their secondary need to determine the phosphate content of relatively thick minable units whose general composition and nature are already fairly well established.

Jan 1, 1949

By Thomas C. Denton

The fluorite, deposit discussed herein occurs on a property known as the Snowball and comprises five contiguous mining claims in Maricopa County, Ariz. Attention of the Bureau was first directed to this property early in 1944 through .a request by D. B. Powell, original locator; to investigate his property as a possible source of fluorite and one that might 'Warrant exploration by the Bureau. The property was examined by two Bureau engineers, Thomas C. Denton and Geo. W. Huseman. It was decided to investigate the occurrence further by trenching, sampling, and diamond drilling. Work began on May 15, 194. Preparatory work, trenching and surface sampling, was supervised by Geo. W. Huseman. Drilling was in charge of R. M. Grantham. The project was completed August 8, 1944.

Jan 1, 1949

By W. N. Lacey, R. H. Olds, B. H. Sage

The volumetric behavior of five mixtures of black oil and natural gas and of two mixtures of condensate and natural gas from a field in the San Joaquin Valley was experimentally established. This work was carried out at roo°, I9o° and 250°F in the pressure interval between 400 and 5000 psi. The viscosity of the liquid phase of four mixtures of black oil and natural gas was experimentally measured in the above-indicated temperature and pressure intervals. The effect of methane upon the precipitation of bitumen from the black oil was studied at 230°F. Introduction The solution of a number of the economical and technological problems which arise in connection with petroleum production is dependent upon the availability of the necessary quantitative information covering the materials involved. This requires data concerning physical properties of naturally occurring hydrocarbon mixtures at the pressures and temperatures characteristic of underground petroleum reservoirs. The experimental determination of the desired data for each situation encountered is relatively time-consuming. However, it is considered to yield results sufficiently more reliable than those obtained from correlations to justify the effort. For these reasons there was undertaken a laboratory investigation of the viscosity of the liquid phase and the volu- metric and phase behavior of mixtures of oil and gas samples obtained from wells in a field located in the San Joaquin Valley. Terminology The nomenclature of petroleum engineering is not at present entirely standardized. Many commonly used technical terms are not everywhere given the same meanings. For the purposes of this paper the following definitions will be adopted: Black oil refers to the dark-colored, hydrocarbon liquid obtained when the producing horizon of the well lies partly in the condensed hydrocarbon phase of the reservoir. Condensate is the term applied to the relatively volatile, pale yellow or amber-colored hydrocarbon liquid that is often obtained from the surface separator system when the producing horizon of the well lies in the gas cap of the reservoir. The gas obtained from the surface separator system is called natural gas regardless of whether the well is producing black oil or condensate. As might be expected from the multi-component character of naturally occurring hydrocarbon materials, the compositions of black oil, condensate and natural gas are subject to considerable variation depending upon the temperatures and pressures prevailing in the surface separator system as well as upon the overall composition of the material produced from the reservoir. In order to obtain samples capable of reproducing the total hydrocarbon material produced by the well, all oil and gas mixtures used in this investigation were com-

Jan 1, 1949

By W. R. Purcell

An apparatus is described whereby capillary pressure curves for porous media may be determined by a technique that involves forcing mercury under pressure into the evacuated pores of solids. The data so obtained are compared with capillary pressure curves determined by the porous diaphragm method, and the advantages of the mercury injection method are stated. Based upon a simplified working hypothesis, an equation is derived to show the relationship of the permeability of a porous medium to its porosity and capillary pressure curve, and experimental data are presented to support its validity. A procedure is outlined whereby an estimate of the permeability of drill cuttings may be made with sufficient acuracy to meet most engineering requirements. INTRODUCTION The nature of capillary pressures and the role they play in reservoir behavior have been lucidly discussed by Lev-rett', Hassler, Brunner, and Deah12, and others. As a result of these publications the value of determining capillary pressure curves for cores has come to be generally recognized within the oil industry. While considerable attention has been directed toward the subject in an effort to provide a reliable method of estimating percentages of connate water, it has been recognized that capillary pressure data may prove of value in other equally important applications. This paper describes a method and procedure for determining capillary pressure curves for porous media wherein mercury is forced under pressure into the evacuated pores of the solids. The pressure-volume relationships ob- tained are reasonably similar to capillary pressure curves determined by the generally accepted porous diaphragm method. The advantages of the method lie in the rapidity with which the experimental data can be obtained and in the fact that small, irregularly shaped samples, e.g., drill cuttings, can be handled in the same manner as larger pieces of regular shape such as cores or permeability plugs. Based upon a simplified working hypothesis, a theoretical equation will be derived which relates the capillary pressure curve to the porosity and permeability of a porous solid, and experimental data will be presented to support its validity. This relationship aplied to capillary pressure data obtained for drill cuttings by the procedure described provides a means for predicting the permeability of drill cuttings. METHODS FOR DETERMINING CAPILLARY PRESSURES Several techniques have so far been employed in determining capillary pressure curves and these fall into two principal categories: (1) Liquid is removed from, or imbibed by, the core through the medium of a high displacement pressure porous diaphragm (2) Liquid is removed from the core which is subjected to high centrifugal forces in a centrifuge4,'. There are? however, certain limitations inherent in both methods. The greatest capillary pressure which can be observed by method (I), above, is determined by the maximum displacement pressure procurable in a permeable diaphragm which at the present time appears to be less than 100 psi. An even more serious limitation of the diaphragm method is imposed hy the fact that several days may be required to reach saturation equilibrium at a given pressure; hence, the time re- quired to obtain a well-defined curve may be measured in terms of weeks. Furthermore, to date, no suitable technique for handling relatively small, irregularly shaped pieces of rock, such as drill cuttings, has been reported and, therefore, measurements must be made, in general, on cores, or portions thereof. The centrifuge method offers the distinct advantage over the porous diaphragm method of arriving at saturation equilibrium in a relatively short time by virtue of the elimination of the transfer medium for the liquid. The calculation of capillary pressures from centrifuge speeds is somewhat tediousa, however, and the equipment required is fairly elaborate. While there exists the possibility that this method might be adaptable to the determination of the capillary pressures of cuttings, this particular ramification has not been investigated, as far as is known. In view of the limitations of the two principal methods for determining capillary pressures, the apparatus described in the following sections has been devised in order that difficulties previously encountered might be circumvented. MERCURY INJECTION METHOD FOR DETERMINING CAPILLARY PRESSURES Theory The methods described above for determining capillary pressures are characterized by the fact that one of the fluids present within the pore spaces of the solid is a liquid which "wets" the solid, i.e., the contact angle which the liquid forms against the solid is less than 90" as measured through that phase. For these "wetting" liquids the action of surface forces is such that the fluid spontaneously fills the voids within the solid. These forces likewise oppose the withdrawal of the fluid from the pores of the solid.

Jan 1, 1949

By A. L. Peyton

Manganese-oxide minerals occur in irregular pockets distributed through the residual clays of the Cartersville district, which lies 45 miles north-west of Atlanta in Bartow County, Ga. The district produces, or has produced, limonite, barite, specular hematite, ochre, ferruginous manganese, manganiferous iron are, as well as manganese. Bureau of Mines engineers have visited the district on three occasions - in December 1939, February 1941, and October 1942. During the visit of February 1941, 80 tons of samples of manganese-bearing clays were taken from seven properties for ore-dressing tests, which were conducted at the Bureau of Mines laboratory at Rolla, Mo. The. October 1942 visit was for the purpose of reappraising the district in the light of knowledge gained from the ore-dressing studies and to prepare a plan for the district's development. Exploratory drilling was begun in March l943 and was continued until June 1945. Nine properties were explored that, roughly follow a line beginning near Cartersville and extend to a point 2 miles northeast of the village of White. The work consisted of bulldozer trenching, rotary bucket churn drilling, sampling, and analytical determinations. The manganese district is 18 miles long with a maximum width of 7 miles at Cartersville, which lies at the center of the district. The work of the Bureau was confined to the northern half of the district between Cartersville and Pine Log. The properties explored comprise but a small portion of the Potential producing area.

Jan 1, 1949

By Unknown

Diesel locomotives for underground haulage have been used in coal mines in Continental Europe for twenty-five years or more. In Great Britain, it was not until 1935 that permission was granted to use them in gassy coal mines, but since that time they have been employed in increasing numbers both in gassy and non-gassy coal mines and in metal mines. Their use underground in coal mines in the United States is still prohibited and the same was the case in Canada until 1946, when permission was granted to operate a Diesel underground in the Adanac mine of West Canadian Collieries, Limited, at Bellevue, Alberta. The locomotive used here is a 50 h.p. Hunslet Mark II. More recently, a 100 h.p. Diesel was placed in operation for underground haulage at No. 18 Colliery of the Dominion Steel and Coal Corporation, in the Sydney coalfield, N. S. Thus, on this continent, Canada has been a pioneer in the use of these locomotives underground in coal mines and there is no doubt that more and more of them will be employed as time goes on. We feel, therefore, that the following notes concerning their design and performance, which we have received from the High Commissioner for the United Kingdom, will be of interest to our members.

Jan 1, 1949

By H. Kenworthy

This report concerns cooperative milling investigations of the Central mill of the Eagle-Picher Mining &. Smelting Co, The work carried on at the Central mill and the Rolla, Station shows that: It is possible to reduce the Central mill heavy-medium plant tailings by 0.05 to .15 percent zinc; the 3/16-inch to 10-mesh fraction of the jig feed can be treated by sink-float to obtain a tailing containing only half as much zinc as the jig tailing; Humphreys spiral concentration of the flotation tailing does not recover enough zinc to be economically attractive; and crushing and wet grinding of ferrosilicon for heavy medium are commercially feasible. The Eagle-Picher Co. operates extensive mines in the Tri-State area of Missouri, Kansas, and Oklahoma. The ore is milled at its Central hill, which also accepts custom ores. During the recent war the mill handled about 12,-000 tong- of low-grade ore per day. The company milled about 50 percent of the district tonnage and purchased nearly 90 percent of the custom ore. About 50 percent of the mill feed was from company mines. Zinc is the chief value in the Tri-State ores,-with Varying quantities of lead and cadmium minerals, as well as small amounts of germanium and gallium.

Jan 1, 1949

By E. R. Brownscombe, Francis Collins

A study has been made of the material balance-fluid flow method of estimating reserves and degree of water drive from pressure and production history data. By considering the effect of random pressure errors it is shown that in a particular example a standard deviation of three and one-half pounds in each of ten pressure survey? permits the determination of the reserves with a standard deviation of 8 per cent and the water drive with a standard deviation of 15 per cent, assuming that certain basic geologic data are correct. It is believed that this method of estimating reserves and water drive is useful and reliable in a number of cases. The method is particularly valuable when reservoir pressure data are accurate within a very few pounds, but may also be applied with less accurate pressure data if a relatively large reservoir pressure decline occurs early in the life of the field, as for example in an under-saturated oil field. INTRODUCTION A knowledge of the magnitude of reserves and degree of water drive present in any newly discovered petroleum reservoir is necessary to early application of proper production practices. A number of investigators have contributed to methods of relating reserves, degree of water drive, and production and pressure history. 1-8 Three types of problems of increasing complexity may be mentioned. If a reservoir is known to have no water drive. and if the ratio of the volume of the reservoir occupied by gas to the volume of the reservoir occupied by oil (which ratio permits fixing the overall compressibility of the reservoir) is known, then only one further extensive reservoir property remains to be determined, namely the magnitude of the reserves. A straightforward application of material balance considerations will permit this determination. The problem becomes very much more difficult if we wish to determine not only the magnitude of the reserves but also the magnitude of water drive, if any, which is present. In principle, a combination of material balance and fluid flow considerations will permit this evaluation. Finally, if neither the magnitude of reserves, the degree of water drive, nor the ratio of oil to gas present in the reservoir is known and it is desired to determine all three of these variables, the problem could in principle be solved by a fluid flow-material balance analysis which determines the overall compressibility of the reservoir at various points in its history. The change in compressibility with pressure would provide a means of determining the ratio of gas to liquid present, since the compressibilities of gas and liquid vary differently with pressure variation. However, in practice this problem is probably so difficult as to defy solution in terms of basic data precision apt to be available.' It is the purpose of this discussion to illustrate the second case, which involves the determination of two unknown variables, single phase reserves and degree of water drive, from pressure and production history and fluid property data, and to study the precision with which these unknowns can be determined in this manner in a particular case. Although an electric analyzer developed by Bruce as used in making the calculations to be described, numerical methods necessary in carrying out the process have been devised and have been applied for this purpose. Schilthuis,' for example, developed a comprehensive equation for the material balance in a reservoir. He combined this with a simplified water drive equation, assuming that the ratio of free gas to oil was fixed by geological data and that a period of constant pressure operation at constant rate of production was available to determine the constant for his water drive equation. On this basis he was able to compute the reserves and predict the future pressure history of the reservoir. Hurst developed a generalized equation permitting the calculation of the water drive by unsteady state expansion from a finite aquifer. He showed in a specific case how the water influx calculated by his equation, using basic geologic and reservoir data to fix the constants, matched the water influx required by material balance considerations. Old3 illustrated the simultaneous use of Schilthuis' material balance equation and Hurst's fluid flow equation for the determination of the magnitude of reserves and a water drive parameter from pressure and production history. He used this method to calculate the future pressure history of the reservoir under assumed operating conditions. As a basis for determining reserves, Old assumed a value for his water drive parameter and calculated a set of values for the reserves, using the initial reservoir pressure and each successive measured pressure. The sum of the absolute values of the deviations of the resulting reserve numbers from their mean value was taken as a criterion of the closeness of fit to the experimental data possible with the water drive parameter assumed. New values of the water drive parameter were then assumed and new sets of the reserves calculated until a set of reserves numbers having a minimum deviation from the average was established. The average value of- the re-

Jan 1, 1949

By John E. Conley

The great demand for metallic aluminum for the prosecution of World War II caused the consumption of bauxite, the common ore of aluminum, to increase greatly. Prior to the war, the domestic deposits 'of bauxite, which occur chiefly in Arkansas and less extensively in Georgia, Alabama, and Mississippi, supplied only: about 30 ,percent of the ore required for aluminum-metal production and approximately 40 percent of alumina for all purposes. Enemy activities during the war seriously interfered with shipment of bauxite from the normal peacetime source in Surinam, Netherlands Guiana, South America, and focused attention on the necessity for increasing production from known domestic deposits. Even in peacetime, the production of aluminum ore in the United States could not satisfy requirements. Field drilling and exploration by Bureau of Mines engineers resulted in the discovery of important tonnages of high-grade bauxite suitable for treatment by the conventional Bayer process, Although an ore containing approximately 55 percent Al2O3 and only 2 to 4 percent SiO2 is preferable, it was necessary to use ores containing up to 8 or 10 percent SiO2. Because of the lower recoveries of aluminum with increased silica content, the Reconstruction Finance Corporation, through the Metals Reserve Company, established a base price of $4 for a 50-percent Al2O3 ore, containing 13-percent silica, with a premium or penalty of 14 cents for each percent of Al2O3 over or under 50; each percent of SiO2 under 13 was awarded a 20-cent premium, and each percent over 13 suffered a penalty of 43 cents; all prices were on the basis of 1 long ton of ore, dry basis.

Jan 1, 1949

By Paul Averitt

The coal-bearing rocks in Iowa occur in an arcuate belt across the central and southern parts of the State (fig. 1) at the northern end of the Western Interior coal field. Coal beds of minable thickness are sporadic throughout this area and are mined principally in the three districts indicated by dark shading on the index map, although coal occurs also in the areas indicated by light shading. The coal is mostly of high-volatile C bituminous rank in all parts of the State. SURFACE FEATURES The coal-bearing rocks in Iowa are concealed for the most part by a covering of glacial drift ranging in thickness from a few feet to several hundred feet. This covering has been dissected to form a gently rolling upland, rising from an elevation of 466 feet at the mouth of the Des Moines River to about 1,200 feet in Calhoun County in the central part of the State. The local relief, however, rarely exceeds 150 to 200 feet.

Jan 1, 1949

By Harold E. Heide

Although the United States has been the largest consumer of tin, only a small quantity of tin was produced or. the North American Continent during peace times, and thy deficiency was made UP by foreign imports. Because the most important sources of tin wore cut off by the war with Japan, it became necessary to increase imports from South America and Africa and, if possible, develop domestic tin reserves. Most of the tin produced in North America has come from the Seward Peninsula, Alaska, and a substantial portion of this was produced from the Potato Mountain area. Tin was first identified as occurring in the Seward Peninsula by A. H. Brooks in 1900, when a part of heavy concentrates from Anikovik River and Buhna Creek, one of its tributaries, proved to be stream tin. 4/ His report was given considerable publicity by the daily press, and the first steamers north in 1901 carried a number of prospectors bound for the Seward Peninsula to search for tin. The deposits of stream tin on Buck Creek in the Potato Mountain area were discovered in the fall of 1901. 2/

Jan 1, 1949

By S. Benedict Levin

The Big mine has been a source of mica and high-grade felspar from separate zones in the same pegmatite dike since 1914. In 1943 it became the outstanding producer of strategic mica in New England. The urgent need for sheet mica led to core-drilling by the Bureau of Mines from February to May 1914. Nine diamond-drill hob's aggregating 1,474 feet in length were drilled by the Bureau of Mines with the objective of developing extensions of the known mica shoots. The use of large-diameter bits made it feasible to obtain reasonably reliable results in diamond-drilling this type of deposit.

Jan 1, 1949

By Jr. Carmichael

"THE MAYO AREA was prospected as early as 1887. The first major activity started in 1898, when the Stewart River and its tributaries were examined for placer deposits, and in succeeding years the district became a small producer of placer gold. The first discovery of the lead-zinc-silver mineralization which has become the main interest of the district occurred in 1906, when a vein was found in the canyon of Galena Creek on the northwest slope of Galena Hill. This deposit was later known as the Silver King mine. In 1919 further discoveries were made on Keno Hill, approximately 15 miles east of the Silver King, the most important being the No.9 vein. Directly or indirectly, these finds are attributable to the search for placer gold, as galena was frequently found in the stream gravels.The 1919 Keno Hill discoveries were acquired by Yukon Gold Co. and operated through a subsidiary, Keno Hill Ltd., from 1920 to 1923. Most of the production came from No.9 vein. In 1921 Treadwell Yukon Corporation entered the field and acquired the Ladue mine. This company continued to operate for 21 years. It acquired in succession the Ladue, Sadie, Friendship, Lucky Queen, Elsa, Silver King, and Calumet mines. Its record of successful operations is very largely the achievement of the late Livingston Wernecke. Under his direction, the Treadwell Yukon Corp. produced metals with a gross value in excess of $21,000,000, in the face of greater transportation problems than exist today and with considerably lower metal prices.Treadwell Yukon ceased operations in 1942. Its entire assets were acquired in 1946 by United Keno Hill Mines Ltd., which has substantially increased the original holdings. It has drawn the bulk of its production from the Hector mine, adjacent to the Calumet. The Hector was not developed by Treadwell Yukon because of legal disputes among the vendors. It has proven to be the largest deposit yet discovered in the district."

Jan 1, 1949

By R. Vernon Helm

Four tables listing values for the various physical properties of those sulfur compounds most likely to occur in petroleum and petroleum products are given herein. The data necessary to bring the first compilation2/ in this subject up to date are given in table I -Revised and Additional Data, which includes boiling points, refractive indices, densities, and freezing points. Tables 11-, III, and IV are published for the first time and include refractive indices for the F, C, and G' lines of hydrogen and the helium D:3 line; surface tensions and viscosities, and refractivity intercepts, specific dispersions, specific refractions, and parachors. The need for information concerning the sulfur compounds in petroleum is becoming-more urgent because of the necessity of refining larger quantities of high-sulfur crude oil to meet the rising demand for petroleum products. For a number of years the Bureau of Mines has been engaged in research to make available more information concerning the properties of the sulfur compounds in petroleum. The petroleum industry has recognized the value of such studies, and as a result the American Petroleum Institute has established Research Project 48A to study sulfur compounds. The investigations under this Project are to be done in Bureau of Mines laboratories as a cooperative project in connection with the work already started.

Jan 1, 1949

By Jack A. Crichton, Henry J. Gruy

This paper discusses methods used in the estimation of natural gas reserves and the general conditions under which the various methods are applicable. The factors used in estimating natural gas reserves are reviewed. Errors which have been found to occur frequently are listed. Introduction The estimation of natural gas reserves has become of paramount interest because of the increasing importance of gas in the nation's economy. Gas is a most desirable fuel, a fact substantiated by the continued rise in the market demand. In addition, new uses for gas are being developed by the chemical, plastic, and associated industries, and plants are being built to make gasoline from natural gas. These are a few of the factors contributing to the importance of the nation's natural gas reserves. With the increased importance of gas there is an increase in the need for reliable estimates of the magnitude and availability of natural gas reserves. These estimates are being used currently: (I) to determine which fields contain sufficient available reserves to justify the construction of pipe-line outlets to serve particular markets; (2) to design pipe lines necessary to serve those fields adequately;] (3) to determine the location of industrial and chemical plants; (4) to finance the development of gas properties, and the construction of gas pipe lines; (5) to determine fair and adequate depletion allowances and depreciation rates; (6) to justify applications for gas pipe lines before various regulatory bodies; (7) to determine the number of wells required to exploit the reserves most economically; (8) to aid in establishing values for the purchase or sale of gas properties, and for purposes of inheritance taxes; (9) to determine equities under unitized operations; (10) to provide a basis for calculating the economics of gas-cycling operations. History or Estimation of Natural Gas Reserves The natural gas industry in the United States had its beginning during 1826 when natural gas was used for lighting the city of Fredonia, N. Y. The first natural gas pipe line was a 25-mi]le wooden line constructed from hollowed logs, connecting West Bloomfield and Rochester, N. Y. There is no record of an attempt to estimate the gas reserve at West Bloomfield but an attempt was made to determine the capacity of the well by measuring the time required to 611 a large balloon. One of the earlier publications concerning estimation of natural gas reserves is the "Manual for the Oil and Gas Industry," published by the Treasury Department, United States Internal Revenue, in i9i9. The following methods of computing "gas depletion" are listed: (I) production decline of the gas well or property; (2) decline in open-flow capacity; (3) comparison with the life history of similar wells or properties, particularly those exhausted Art

Jan 1, 1949

By John C. Lyons

"The Wabana iron ore deposits occur as flat-dipping beds of oolitic hematite and chamosite, of Lower Ordovician age, which outcrop for 3 miles along the northwest coast of Bell Island, Conception Bay, Newfound-land, about 16 miles from St. John's.The deposits occur in three zones, Upper, Middle, and Lower beds, separated respectively by 30 feet and 215 feet of shale and sandstone. They are primary sediments laid down in a shallow tidal basin by the precipitating action of a marine environment on iron-rich fresh waters flowing into the basin.The ore-bearing zones, while of wide areal extent, are not uniform beds of hematite that can be mined wholesale. The action of waves and currents during sedimentation; the delta pattern, velocity, and transporting power of streams flowing into the basin; the contours and oscillations of the sea bottom on which the sediments were laid have all been fundamental in the emplacement of richer and thicker mineable sections, and of lean zones so intercalated with shale as to be unmineable.The preservation of the deposits is due to their location in the Conception Bay syncline and to a considerable upthrust of the country east of the bay in post-Ordovician time.The hematite deposits were first recognized as such in 1892, and soon after were acquired by the Nova Scotia Steel and Coal Co. They are now being mined by Dominion Wabana Iron Ore, Limfred, a wholly owned subsidiary of the Dominion Steel and Coal Corporation, Limited. Production started in 1895, and up to the end of 1955 totaled 58,588,516 long tons of hematite ore, having an average dry analysis of about 51 5 per cent iron, 11 8 per cent silica, 0·9 per cent phosphorus, and l ·5 per cent moisture. About 40 per cent of the total tonnage mined has come from surface stripping and on-shore mines. These areas have now been almost completely depleted, and operations are confined to submarine mines extending for two miles off shore under the waters of Conception Bay. Three sub-marine slopes are currently in operation, Nos. 3 and 4 working in the Lower Bed and No. 6 in the Middle Bed. A general picture of the workings is shown in isometric projection in Figure 1. Submarine mining has been entirely by the room-and-pillar method, with an extraction of 60 per cent. The deepest workings, at a vertical depth of 1,850 feet below sea-level, have a rock cover of about 1,500 feet. No mining is done in areas where the rock cover is less than 200 feet. To date mining has explored six square miles of a potential area that may exceed 50 square miles."

Jan 1, 1949

The purpose of this paper is to list by tabulation and flow sheet, the operating equipment and installations in use at Rosebery, and to refer to particular items which may be of interest for purposes of comparison, or because they possess some unusual feature. The general perspective has been taken from the viewpoint of operating and maintenance experience.The sequence begins with ore breaking and transport and proceeds through milling operations. The paper is in two sections, first, mechanical equipment, second, electrical equipment. A brief outline of a scheme for using gravel wash for stope filling, which is in course of installation, has also been given.

Jan 1, 1949

By M. J. S. Innes

Abstract This paper is an account of an investigation made by the Dominion Observatory with a gravity meter and magnetometer over sulphide concentrations at East Sullivan, Val d'Or, Que., in June, 1947. The topographic relief over the area does not exceed 20 feet. The overburden varies from 0 co 50 feet. The west orebody had been outlined by extensive drilling. The average density contrast between the sulphide body and surrounding rocks is 0.5. Two hundred and sixty gravity and one hundred and ninety magnetic stations were observed. The results are shown on contour sketches. A derailed account is given of the methods employed to reduce the gravity observations. The survey shows that both gravimetric and magnetic methods are useful in delineating sulphide deposits under the conditions in which they occur at East Sullivan. The results indicate that the buried contact of the syenite intrusive southeast of the orebody could be traced with the gravimeter and chat the magnetometer was of little value for that purpose. Gravity anomalies due to the varying depths of overburden are negligible as compared to the magnitude of the total anomalies. Introduction The project was first suggested at a meeting of the Associate Committee on Geophysics of the National Research Council in September, 1946. At that time it was pointed out that the accuracy and speed of operation of the new gravity meters made them of special importance for geophysical prospecting and it was highly desirable to have an objective test of the performance of an instrument of this kind in delineating an orebody of known dimensions and density characteristics. Several years ago, a private company did some work with a gravimeter over the Amulet deposits, near Noranda. Unfortunately, the topography there is rather rugged, with hills and ravines exceeding 100 feet, so that the topographical effects rendered it impracticable to distinguish between anomalies due to the sulphides and those due to surface irregularities. An orebody of a typical nature, where the disturbing topographical corrections were not excessive, was therefore sought.

Jan 1, 1949