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By Oliver B. Hopkins

Peru produced approximately 17,466,620 bbl., of oil during 1937, or slightly less than the record high of 17,593,700 bbl. established during 1936. As in 1936, the entire output of the country was derived from the La Brea-Parinas, Lobitos-Restin and Zorritos fields in the northwestern part of the country. Outside of the proven areas, drilling was 'continued by the Peruvian Government in the northern province of Tumbes on the reserved zone at Zorritos. Drilling was carried out on three locations, two of which are understood to have been abandoned during the year. In southern Peru, further attention was given by Government engineers to the Pusi and Saman districts and plans are being worked out for the commencement of drilling operations in the near future in the vicinity of Pirin. Activities in the montaiia region in eastern Peru were continued by the Compafiia Petrolera El Ganso Azul. This company acquired the interest of the Selden Breck Co., and holds some 90,000 acres along the Pachitea River a few miles above its confluence with the Ucayali. During the year, the preparation of a landing place, the cutting of a 12-km. (71/2-mile) road from the river to the drill site, and the construction of a camp were undertaken. Equipment for drilling on this company's concessions has already arrived in South America. La Brea-Parinas Estate.—Production of crude oil on the La Brea-Parinas Estate of the International Petroleum Company Limited amounted to 14,722,754 bbl. during 1937, a decrease of 403,736 bbl. from the all-time high reached during 1936. The total production from 1890 to Dec. 31,1937, was 178,390,767 bbl. During 1937, a total of 141,653 ft. was drilled, 129,516 ft. in new wells and 12,137 in deepening existing wells. In all, 57 wells were completed, 47 of which produced oil, 2 were gas wells and 8 dry. holes. Twenty-nine wells were cleaned out or deepened during the year. The average depth of new wells completed during 1937 was 2367 ft. compared with 1984 ft. for the new wells completed during 1936. There was an increased use of rotary tools during the year and this method is now used to a greater extent than the cable-tool method, which formerly predominated. Of the 57 wells completed during the year, 31 were

Jan 1, 1938

By Hamilton Bell, E. W. Webb

RepressuRIng, or gas drive, was first tried in the Seal Beach oil field during the fall of 1927, and was carried on until the spring of 1928. This experiment in the Upper or Bixby zone was highly successful in proving the feasibility of compressing gas to high pressures and also showed great increases in production. The project was discontinued because there were not enough wells to protect the property lines. In the development of the second or Selover zone, many more wells were drilled and after 2½ years of production the gas was depleted so that all producing wells in the zone were either pumping or on gas-lift. Edge-wat'er encroachment and the deepening of wells on neighboring properties to a third zone practically isolated the lease, so that during the spring of 1929 it was considered feasible to repressure the Selover zone on the Bixby lease of the Continental Oil Co. (Marland). As shown on Fig. 1, the main Seal Beach structure is an elongated dome with a northwest-southeast trend, and the north flank is cut by a fault nearly parallel to the axis of the structure. Bixby well No. 24 was chosen for the injection well on account of its location, as it is backed up by the fault and is surrounded by wells that protect the property lines. The results of the test made in the Bixby zone indicated that an injection well on the flanks of the structure would drive oil quickly to up-structure wells but would have a tendency to cause by-passing, while the drive to down-structure wells would be slower but more evenly distributed. Preferably the injection well would have been located on top of the dome but property divisions made this inadvisable. Well 24 had been completed in November, 1928, but on account of gas depletion the well failed to flow naturally. On gas-lift the well had an initial production of 1000 bbl. of oil with 30 per cent. emulsion. This well is 4825 ft, deep, penetrating 200 ft. of oil-bearing formation. At the time the well was prepared

Jan 1, 1930

By Herbert Hoover

DURING the year, the' Institute has made the most remarkable growth in its history. Our actual increase in membership was 1816 and therefore was 80 per cent. larger than any previous year. Even without expectation of any abnormal growth, we should pass in the year 1921 the 10;000 mark. The causes of this increased growth are not far to seek.. They lie in the widening vision of the Institute's work, not only in its relation to' the profession but as an avenue of service to the nation as a whole. The Institute is today in the first rank of influence among public institutions in the country. During this year we have, for the first time in many years, had a ?deficit of some $3000 in our finances. The sum is not important, but it- does indicate the tendency of the times, and that is the high cost of living:' The increase in our expenses lay, to the largest degree, on the publishing side of the Institute's work. If we compare the year 1918, as a fairly repre¬sentative year, with that of 1920, we find that the costs of issuing the' Institute's publications, after deducting the income received from these publications, shows a .net increase of about $33,000. for the year. This has been to some degree due to the enlarged membership but to a large degree due to the cost of the paper and printing.

Jan 1, 1921

By M. D. Hassialis, C. G. Myer

THE nature of a collector-coated mineral surface has been the subject of some experimentation and much speculation. Various aspects of the problem have been isolated and studied; it is probable, however, that there exist aspects as yet unrecognized, which are needed for a complete description of the system. The recognized elements of the problem are: 1—The nature of the chemical units comprising the film and the nature of the forces holding these chemical units to the mineral surface; 2—The orientation of the chemical units at the surface; and 3—The disposition of the collector units at the mineral surface. This report touches upon all three aspects of the broad problem; it deals, however, with a new and heretofore unrecognized element—the mobility of the collector units in the two dimensions of the solid-liquid interface. Regardless of the viewpoint adopted as to whether the chemical units comprising the collector film are collector ions or molecules, held either by chemical or physical forces, the writers on flotation theory are in apparent agreement as to the orientation of the chemical units at the mineral surface. Wark and Cox' showed that the contact angle at a stable collector-coated surface in a constant chemical environment is independent of the nature of the mineral and of any resurfacing agent; it depends solely upon the collector used. They showed further that the value of the contact angle increases with the number of carbon atoms in a homologous series of compounds. Taggart, Taylor, and Knoll2 postulated that the collector ion is oriented with the chemically reactive, polar end toward the mineral surface and the non-polar, hydrocarbon-like end toward the liquid phase. In support thereof they cited the abstraction of p-p1 dihydroxydiphenylthiourea and of glycol xanthate8 by galena without a concomitant increase in the contact angle above that of clean galena. It was argued that in these cases the water-repellent layer which normally would be presented to the liquid phase owing to the orientation of the collector ions is overlain by a layer of water-avid groups, the hydroxyl groups. Implicit is the analogous orientation exhibited by a monomolecular layer of an insoluble substance at an air-water interface. It should be pointed out that these facts also are consistent with the concept that the collector units be flat on the surface of the mineral and that the response of the surface to an air bubble is determined by the ratio of the area covered by water-avid groups to the area covered by water-repellent groups; the areas being weighted according to the relative watef-avidity or water-repellency of the groups involved. The disposition of the chemical units of the collector film at the mineral surface has not received the attention it merits. Taggart4 concluded from the observed stoichiometry of the ions entering and leaving a surface that the stoichiometry is obeyed in detail at the surface of the mineral. Thus, in the case of xanthate-coated galena, pairs of xanthate ions are attached to surface lead ions. In the case of chemisorption, Gaudin and Preller postulated an agreement between the atoms or ions of the substratum (the mineral surface) with those of the superstratum (collector film); in the case of the physical adsorption their position is not clear. In one place they state "the first type (physical adsorption) does not require any agreement between the atoms or ions of the substratum with that of the superstratum" and in another place that "It seems, in fact, as though some slight influence of the substratum is formed even in physical adsorption." The present work shows that in some cases of chemisorption the chemical units of the collector film are in constant surface-bound motion and may not be assigned to any site of the surface, hence there is no permanent association between the chemical units of the film and the atoms or ions of the solid. The physical property of the collector film that is of paramount importance is its surface energy. Although this property is not susceptible to direct experimental determination, the related contact angle is. Much of the knowledge of the properties of a collector film derives (by deductive and inductive reasoning) from the behavior of an air bubble thereat

Jan 1, 1952

By Renato G. Bautista, Gary A. Beetner, Anthony L. Frey

The flow of material in a pump mixer-settler extractor was studied photographically and visually by injecting dye into the equipment and following its advance through the various sections of the equipment. Volumetric measure of the flow was obtained from analysis of the photographs. The organic portion of the settling chamber, the fluid surrounding the pump mixer, and the pump mixer itself were found to be operating in plug flow. The aqueous portion of the settling chamber was found to be partially mixed. Significant dynamic effect was noted due to density changes in the feed streams. The quantitative and qualitative observations made of the flow within a single stage should be of value in predicting the flow patterns in all similar equipment, including opaque and liquid metal solvent extraction systems.

Jan 1, 1973

By AIME AIME

ENGINEERS in the past have been largely associated with private enterprise and there has been a considerable tendency on the part of some members of our profession to depreciate government service for engineers. We engineers must change our mental attitude about employment in government service, particularly in view of the present most friendly attitude of the U. S. Civil Service Commission toward engineers for major posts in our Government. We must also take a much more active interest in public affairs. It must be realized that the national-defense program, which we are now organizing, will require for its effectiveness large numbers of engineers skilled in a wide range of technical and administrative services. In fact, the success of this undertaking will depend largely upon the extent to which our Government can command expert engineering talent to serve during the emergency. There is an acute shortage of technical and supervisory engineering personnel not only in the industries concerned with national defense but also in the Army, Navy, and other defense agencies of the Government. By an Act of Congress, approved on Oct. 9. 1940. $9,000.- 000 was turned over to the U. S. Office of Education, the regular defense agency of the Government which has co-operated with higher education for

Jan 1, 1941

By Thomas R. Couzens

Jan 1, 1985

By H. E. Wrigley

The boundaries of the oil region in Pennsylvania and New York, as determined by the drill, embrace a much larger extent of territory than is generally supposed, being nearly 200 miles in length from north to south, with an average width of 25 miles, covering an area, within somewhat irregular lines, of about 4250 square miles. After twenty years of development we find these lines practically the same as those laid down by McClure in his geological map of the United States, published in 1817, and denominated and colored by him as the "line of salt," which was found in quantity long before petroleum. The eastern line of the entire oil region lies in a northeast and southwest direction, parallel to and some distance west of the Allegheny Mountains; the south line is substantially one drawn between the western boundary of Butler County and the town of Kittanning in Armstrong County; the west line passes just outside of Butler County, cutting off a small corner of Mercer, west of the towns of Franklin, Titusville, and Warren, into New York State, where it rounds off the end of this long strip in the counties of Allegheny and Cattarangus, and joins the eastern line, near Olean, New York, north of the city of Bradford. (See map.) The eastern line, starting from Kittanning, passes through the northeast corner of Clarion County, the southeast corner of Warren, cutting Forest County through the centre, and reaching the beforementioned extreme northeastern developments near Olean. These lines have been taken broadly to include all territory that could ever possibly come into the question as oil-producing. These lines having been proved by the drill may be considered

Jan 1, 1882

By Bernard H. Coyle, Robert N. Anderson, Judith A. Koperski

Between 6 and 8 million cars are shredded annually in the U.S. This shredded material is magnetically separated leaving a mixture of nonmetallics and nonferrous metals which can be further separated into its metallic and nonmetallic constituents. The metallic portion is a mixture of metalr; and alloys containing predominately zinc, and some aluminum, copper, and residual iron. Hydrometallurgical strategies are proposed for recovering the aluminum, copper, and zinc. The thermodynamic and kinetic behavior of the most promising alternatives to separation are discussed.

Jan 1, 1978

By Eugene R. Rice

(Canal Zone Meeting, November, 1910.) THERE are many methods for determining the meridian, but all of those in common use involve at least two separate observations, one for latitude and one for azimuth. Such observations made upon a south star at any hour are open to the objection of possible inaccuracy due to ignorance of the absolute refraction, and also to slow change in the altitude of the star when near the meridian. The method of observing a circumpolar star at elongation, besides requiring a separate observation for latitude, is open to the serious objection that clouds may obscure the star at the critical moment. Moreover, a tedious wait for the star to come to elongation is sometimes necessary. Many of us can recall long, cold, weary vigils, waiting for Polaris to reach elongation. For observing a circumpolar star at any hour, not only the latitude, but also the true time, must be known. This it is practically impossible to obtain, except in regions reached by the telegraph, and usually then one has to know the longitude also, in order to reduce "standard time" to "local time." The results obtained by this method, when the star is at culmination, are not very good, unless the true local time is absolutely known. The methods of obtaining the meridian from the sun, by means of a solar attachment, or by direct observation, while good, are not absolute, by reason of refraction, change in declination of the sun, and small change in vertical angle, when the sun is near the meridian. For these two methods, latitude, time, and approximate longitude have to be known. In the method here described, only one observation is needed, and from it azimuth, latitude, and sidereal time are computed. In other words, one can observe a circumpolar star-Polaris

Nov 1, 1910

Oceanographers are tooling up. Back of the build-up is Navy defense work and private business. Business is dipping toes in the ocean gingerly and not sure whether the motivation is based on logic or intuition. The problem is that new business opportunities in the oceans could explode rather than evolve. The question is when. At stake for earthlings are food supplies, mineral resources, oil and gas, weather forecasting, navigational systems, shore erosion control and sewage disposal, as primary targets. "Twenty years ago, offshore oil seemed a remote possibility for economic exploitation but today it is a reality. It became a reality largely because of the development of practical ocean seismic equipment and drilling platforms. Today the oil industry is looking at submerged-type drilling rigs. Mineral exploration in the sea is more expensive than on land now primarily because familiar land tools are being modified for sub- marine work." These were the ideas expressed by C. G. Welling of Lockheed Missiles & Space Co., at one of the many meetings that have taken place so far this year on development of marine resources. Welling's views indicate the rationale of companies that have already invested in the sea. Many companies, including those in mining, have observers who caution, "go slow." The continental shelfs and even the deep ocean floor represent to the mineral industries the age-old, enigmatic confrontation-is this the time to move? To no other industry, except Defense, are the results of correct timing so vital.

Jan 8, 1967

By O. M. TUPPER

REQUIRING a finer ground clay than that obtainable with a dry pan or hammer mill, the Clay Corporation of California installed a five-roller, low- side Raymond impact mill at its Lincoln plant in 1925 and since then has been economically grinding fire clay with a moisture content as high as 15 per cent. This was one of the first, if not the first, of this type of mill to be used in the grinding of clay on the Pacific coast. The pulverizer consists of a die-ring, lying in a horizontal plane, enclosed in a sheet-iron housing. A vertical shaft supports a spider from which five rolls are suspended in such a way as to always have them bearing on the die-ring. The vertical mill shaft is driven by means of beveled gear and pinion from a horizontal shaft which is connected by belt with a 60-hp. motor with suitable pulleys to give a speed of 175 r.p.m. A large fan which has a speed of 1100 r.p.m. and is belt connected to a 40-hp. motor is connected to the mill housing. The discharge end of the fan is in turn connected to a cyclone dust collector.

Jan 1, 1929

By Phillip Philbin, Frank E. Senftle

A field neutron activation analysis technique suitable for determining uranium in ores has been tested. The method is based on the measurement of the 74.7 keV gamma ray from 'U. When the thorium/uranium ratio is greater than one or the vanadium is greater than 1%, a low uranium analysis is obtained. No satisfactory correction for thorium has been found, but a correction for vanadium can be deter¬mined. For ore containing greater than 0.01% uranium, the uranium can be deter¬mined with an accuracy of about 10% which is quite adequate for a field exploration technique.

Jan 1, 1972

By Allan D. Taylor, Robert S. Shoemaker

Adopting as a principle the phrase "the mill of yesterday should not be built with the high cost money of today," the authors have designed a hypothetical concentrator which could be built for a typical southwestern United States (or other similar area) copper ore. Many of the design features could also be used for other ores in other climates. Functional design, large equipment, and outdoor type of construction have been combined in a concentrator (which includes all ancilliary facilities such as truck and maintenance shops, offices, warehouse, nominal tailings disposal, and water supply) which could be built today for substantially less than the cost of comparable but conventional plants.

Jan 1, 1973

By Richard A. Mullins, James J. Merle

Systematic sampling and analysis in coal-washing plants results in product control and economical operation. A well-organized laboratory system reduces operating costs and increases sales if the operating and sales companies make full use of information it supplies. The operating cost of a control laboratory is less than 1 pct per ton of coal produced. THE system of laboratory control as practiced by the Ayrshire group of mines was begun with the construction and organization of the first laboratory in conjunction with the completion of its first wash-ery in 1941. The primary purpose of this laboratory was to maintain a check on the quality of the coal produced from the washing plant. The laboratory was equipped to determine proximate analyses, float-and-sink tests, and screen analyses, and was staffed by a chemist. an assistant. and a technician. Members AIME, are Assistant Preparation Manager and Chief Chemist, respectively, Ayrshire Collieries Corp. and Subsidiaries, Danville, Ill. Joint AIME-ASME Fuels Conference. French Lick. October 1949. TP 2855 F. Discussion (2 copies) may be sent to Transactions AIME before June 30, 1950. Manuscript received Aug. 22, 1949. Soon it became apparent (1) that product control could be accomplished, (2) that a substantial reduction in operating costs could be effected by close control of coal losses in the rejects, and (3) that information furnished by the laboratory was of continuous value to the operating and sales companies. Consequently the laboratory function was expanded to supply them with additional data as required. As the parent company expanded and new mines were added, control laboratories were established at each mine equipped with washeries, and a central laboratory was maintained at one of the mines that was located equally convenient to all of them. A well-planned control laboratory assures production of a uniform, high-quality product. Whenever coal of substandard grade is loaded inadvertently, the sales company can be informed and the proper channel of distribution made. Conversely only constant and strict laboratory supervision can insure proper production of the various grades. Knowing the product, the producer can keep out of many customers' arguments that may be both awkward and expensive. Double checking between customers and mine laboratories have solved many disputes' Some nager insist On buying coal On the analysis basis only, with penalties for substandard coal and premiums for coal above normal quality. A substantial percentage of the coal sold by the Ayrshire group is of this nature. The usual procedure is for the customer to sample and analyze the coal as it is unloaded at the plant, and the mine laboratory samples it as it is loaded at the mine for subsequent analysis by the central laboratory. Only the unloaded moisture is considered, rather than the average of mine and plant moisture, and the buyer sends duplicate samples to the central mine laboratory for this determination. The average of the two analyses determines the price of coal at the mine. In this particular case, the laboratory plays an important part in increasing realization for two reasons: (1) every attempt is made to maintain plant efficiency and product quality as high as possible, (2) check on analyses and sampling by the buyer or seller.

Jan 1, 1951

By Richard A. Mullins, James J. Merle

Systematic sampling and analysis in coal-washing plants results in product control and economical operation. A well-organized laboratory system reduces operating costs and increases sales if the operating and sales companies make full use of information it supplies. The operating cost of a control laboratory is less than 1 pct per ton of coal produced. THE system of laboratory control as practiced by the Ayrshire group of mines was begun with the construction and organization of the first laboratory in conjunction with the completion of its first wash-ery in 1941. The primary purpose of this laboratory was to maintain a check on the quality of the coal produced from the washing plant. The laboratory was equipped to determine proximate analyses, float-and-sink tests, and screen analyses, and was staffed by a chemist. an assistant. and a technician. Members AIME, are Assistant Preparation Manager and Chief Chemist, respectively, Ayrshire Collieries Corp. and Subsidiaries, Danville, Ill. Joint AIME-ASME Fuels Conference. French Lick. October 1949. TP 2855 F. Discussion (2 copies) may be sent to Transactions AIME before June 30, 1950. Manuscript received Aug. 22, 1949. Soon it became apparent (1) that product control could be accomplished, (2) that a substantial reduction in operating costs could be effected by close control of coal losses in the rejects, and (3) that information furnished by the laboratory was of continuous value to the operating and sales companies. Consequently the laboratory function was expanded to supply them with additional data as required. As the parent company expanded and new mines were added, control laboratories were established at each mine equipped with washeries, and a central laboratory was maintained at one of the mines that was located equally convenient to all of them. A well-planned control laboratory assures production of a uniform, high-quality product. Whenever coal of substandard grade is loaded inadvertently, the sales company can be informed and the proper channel of distribution made. Conversely only constant and strict laboratory supervision can insure proper production of the various grades. Knowing the product, the producer can keep out of many customers' arguments that may be both awkward and expensive. Double checking between customers and mine laboratories have solved many disputes' Some nager insist On buying coal On the analysis basis only, with penalties for substandard coal and premiums for coal above normal quality. A substantial percentage of the coal sold by the Ayrshire group is of this nature. The usual procedure is for the customer to sample and analyze the coal as it is unloaded at the plant, and the mine laboratory samples it as it is loaded at the mine for subsequent analysis by the central laboratory. Only the unloaded moisture is considered, rather than the average of mine and plant moisture, and the buyer sends duplicate samples to the central mine laboratory for this determination. The average of the two analyses determines the price of coal at the mine. In this particular case, the laboratory plays an important part in increasing realization for two reasons: (1) every attempt is made to maintain plant efficiency and product quality as high as possible, (2) check on analyses and sampling by the buyer or seller.

Jan 1, 1951

By John P. Huger

me phase diagram for the system Ag-Si has been established by thermal analysis. The diagram is a simple eutectic type with a eutectic at 3.0 pct Si and 840°C. From the liquidus curve and with the aid of regular solution theory, the thermodynamic properties of the liquid Ag-Si system at 1420 °C have been determined. Silicon exhibits positive deviations from Raoultain behavior at all compositions, while silver exhibits both positive and negative deviations. MEASUREMENTS of silicon activities in liquid iron alloys by means of distribution studies between the immiscible liquids silver and iron have been reported by Chipman, Fulton, Gokcen, and caskey.' The applicability of this technique is dependent, however, on the accuracy of the silicon activity values in the Ag-Si alloys, particularly in the dilute silicon region. Darken and Gurry2 have shown that log ?si/(1-xSi)2 is approximately linear with composition, but uncertainty exists in the extrapolation to dilute solutions. Their calculations are based on the old Ag-Si phase diagram of Arrivaut3 and any variation in the position of the liquidus curves will strongly influence the extrapolation. The purpose of this study is to redetermine the Ag-Si phase diagram and calculate the associated thermodynamic properties. EXPERIMENTAL The Ag-Si phase diagram was determined by thermal analysis of liquid alloys. The alloys were contained in a 35 mm alumina crucible under a protective stream of purified argon. The crucible was placed inside a 64 mm alumina tube fitted with a gas-tight, water-cooled, copper head. The tube and assembly were heated in a manually controlled globar furnace. The temperature was measured with a Pt, Pt + 10 pct Rh thermocouple in a high-temperature porcelain protection tube. The thermocouple calibration4 was checked against the melting point of pure silver at the start and during the course of the experiments, and against both gold and silver at the completion of the experiments. The alloys were prepared from granular silver analyzing 99.95 pct Ag and powdered silicon analyzing 99.88 pct Si and 0.026 pct Fe. Approximately 150 g of alloy were used for each run. The composition of the alloy was determined by withdrawing samples of the liquid alloy with a vycor tube-aspirator bulb device. Analysis of solidified samples agreed, for alloys containing less than 23 pct Si, within ±0.3 pct Si of the calculated composition. Duplicate samples showed a variance within 50.05 pct Si of the mean analysis. The alloy was heated to 100' to 20pC above the estimated liquidus temperature and then the furnace was adjusted to give an average cooling rate of 2" to 7°C per min. A cooling curve was obtained by taking potentiometer readings at 15-sec intervals. Several analyses were made by recording the thermocouple output on a high-speed, Stip-chart recorder, with the exception of run NO. 11, a minimum of two thermal analyses were made for each alloy and the cooling curves then obtained duplicated the liquidus and eutectic temperatures to about 1°C. RESULTS The results of the thermal analysis are given in Table 1, and are represented as the Ag-Si phase dlagram, Fig. 1. The eutectic composition was found

Jan 1, 1963

By John C. F. Randolph

Although China is believed to contain an enormous coal-area, but few memoranda have been published as to the character of its coals. Our belief as to the extent of its coal-fields rests mainly on the statements of travellers of all classes, religious, scientific, etc.,

Jan 1, 1887

By Victor E. Saouma

Chip formation in rock under a line load and in front of a drag bit cutter is numerically investigated. Analysis is accomplished by a special purpose interactive graphics finite element code, SICRAP, written for the simulation of mixed mode crack propagation under 1inear elastic fracture mechanics assumptions. The first study provides some interesting qualitative results, and in the second study, correlation with experimental tests on chip formation by drag bit cutter in Berea sandstone is found to be very satisfactory. This indicates that elastic analysis, coupled with fracture mechanics, is capable of modeling rock cutting.

Jan 1, 1984

By J. L. Martin, W. M. Campbell

A new electric logging method, called displacement logging, often gives a direct indication of the presence of mobile hydrocarbons in hydrocarbon-bearing formations. This method is based on the detection of a bank of connate water which is formed between the invading mud filtrate and virgin formation fluids in these cases. The existence of this phenomenon has beer, verified by laboratory studies and by actual field logs taken in known oil sands. INTRODUCTION During the past decade increasing use has been made of conventional electric logs to determine the amount of oil or gas in formations traversed by a borehole. This determination requires knowledge of several factors, such as true resistivity of the formation, formation factor, and water resistivity. Sometimes all of the factors necessary to make a reliable saturation calculation are not available. Also, the computations and corrections which are necessary in such a study often require the services of an experienced log analyst. It has long been the desire of exploration people to have a logging device which will locate hydrocarbon-bearing formations directly without requiring complex interpretation methods. The displacement log, while not completely fulfilling this desire, appears to be a Step in that direction. Basis for the Device The basis for this device stems from a phenomenon which occurs when mud filtrate invades a formation which contains displaceable hydrocarbons. As the mud filtrate invades the formation, most of the oil or gas is pushed out of the invaded zone, leaving residual oil. However, in addition to displacing most of the oil or gas, the connate water is also swept out, since the originally irreducible water is mobile in the presence of a water phase.1,2,3 Tonsequently, this irreducible water piles up as a bank between the virgin oil zone and the invading filtrate. If the mud filtrate is of higher resistivity than the formation water— as is commonly the case—the resulting annular zone, containing the bank of formation water, will be of lower resistivity than either the virgin oil-bearing formation resistivity or the invaded zone resistivity. This resistivity configuration, going from high to low to high again as the distance from the borehole increases, is found only in those zones which contain displaceable hydrocarbons. A device which would reliably detect this low resistivity zone would give a direct indication of mobile hydrocarbons. Illustrations This phenomenon is illustrated in Fig. 1 and 2. Fig. 1 shows a sketch of a zone containing salty connate water plus displaceable hydrocarbons, along with graphs showing fluid content and electrical resistivity vs distance from the borehole, before invasion occurs. Fig. 2 shows this zone, together with fluid content and resistivity graphs. after invasion by a fresh water mud. The resistivity pattern on moving away from the borehole is high: low: high. The absence of the low zone phenomenon in water zones is illustrated in Fig. 3 and 4. Fig. 3 shows a sketch of a zone containing salty formation water and residual oil, along with graphs showing fluid content and electrical resistivity vs distance from the borehole, before invasion occurs. Fig. 4 shows this water zone, together with fluid content and resistivity graphs, after invasion bv a fresh water mud. In this case the resistivity pattern on moving away from the borehole is high: low since there is no change in water saturation at the head ol

Jan 1, 1956