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Andes Copper has an old camp and a new camp, both isolated until recent road improvements. The old camp is at Potrerillos and the new one at El Salvador, 25 road ,miles away. The company was incorporated in 1916 and the first mine, concentrator, leaching plant, smelter and town were built in the succeeding twelve years. The first blister copper was poured on January 24, 1927. Economic conditions determined the long development period but the end result was the design and construction of a mining complex that was all of a piece, unlike the piecemeal additions to El Teniente and Chuqui. The mining episode at Potrerillos came to an end in 1960 when the ore at La Mina became exhausted and the new mine, El Salvador was brought in. Both of these ore deposits come within four hpundred feet of the surface and had they been developed within the last five years might reasonably have been brought in as open pit mines. However, that is conjecture, and as it stands the operation at La Mina was so ideal for the mining method selected, blockcaving, it became a classic for the textbooks. On the other hand, El Salvador has turned out to be a blockcaving mine to test an engineer's skill. In mining the copper deposit at Indio Muerto mountain, there are ground conditions of every conceivable type. Tunneling in one section, the back can cave like sized pea gravel and only spiling can hold it; in another heading only the lifters are shot but often the rest of the round will sit down in one piece; elsewhere the bottom squeezes up and closes the drifts; and contrary to all other locations, there are sections where the block can be undercut without support. Today the scope of operations at Andes extends from mining to electrolytic copper. Ore is mined at El Salvador and the concentrator is also situated there. Concentrates pipelined 14 miles to Llanth, the water decanted, and then it is hauled by rail 40 miles and 5500 ft higher to the Potrerillos smelter and refinery. Potrerillos and El Salvador are respectively 90 and 70 miles from the port of

Jan 11, 1969

By William Metcalf

IT is the object of this paper to oppose unnecessary changes, and the introduction of new and confusing terms. From the earliest times of which we have any record on the subject, iron has been divided into general classes. Whether iron was first known in the form of wrought iron or of steel, is a matter of no importance; but at the time when cast iron first became a prominent article of commerce, wrought iron and steel were old products¬steel, at that time, being generally made from wrought iron by the process of cementation. As steel was then properly defined as iron containing more carbon than wrought iron, so cast iron was appropriately defined as iron containing more carbon than steel. Until the year 1776, when Huntsman first began the manufacture of a new kind of iron by melting wrought iron and steel in crucibles, the above definitions were all that could be desired. At first, probably, owing to imperfect appliances, only a highly carburized iron was melted in crucibles, and this led to its being called cast steel. If our ancestors had found a name for this material not involving the use of the word steel, we would have been saved the trouble of the present discussion. As the arts developed, new uses were found for steel, and the products of the crucible were varied, until at the present day it is quite common to find steel containing no more carbon than average wrought iron, and other steel containing nearly or quite as much carbon as some cast iron. All of these various products of the crucible have retained, or received, the name cast steel, usually abbreviated to the simple word steel, without causing any confusion among producers or consumers in regard to terms or their meaning. In 1855, twenty-one years ago, the Bessemer process was introduced ; this was followed in a few years by the Siemens-Martin process, and the products of both were at once, and have ever since been, called steel, from the fact that they were identical in chemical and physical properties with crucible cast steel. At the present time, then, we have three subdivisions of cast steel, viz.: Crucible cast steel, Bessemer cast steel, and Siemens-Martin,

Jan 1, 1877

By Robert D. Coale, Reinhart P. Ehrlich, Terry L. Thompson

The copper concentrate slurry pipeline and pumping system of the Bougainville Copper Ltd. facilities on Bougainville Island in Papua New Guinea, is discussed. Development work necessary for the pipeline design is dealt with including a description of the 17-mile by 6-in. pipeline and pumping system as it was installed. The commissioning of the pipeline is reviewed as well as current operating performance, including data on corrosion, pump parts life, and manpower requirements.

Jan 1, 1977

By Norman Weiss

The need for more efficient utilization of labor in the metal-mining industry has been the subject of several recent editorials in the mining press, and one attractive possibility for such improvement lies in the designing of future milling plants particularly with economy of manpower in mind. We are accustomed to think of mill design as the selection and coordinated arrangement of process equipment, but if labor is to be efficiently utilized it must be given early consideration in planning the new mill. There are three good reasons for economizing in labor: (I) to reduce costs, not only in the form of wages but also in housing, hospital, welfare, and other obligations that a company accepts when a new man is added to the payroll; (2) to prepare for recurrent periods of manpower shortage, during which a well-designed plant can manage to get along with skeleton crews; (3) because a milling plant that must depend upon an inordinately large labor force for its operation and maintenance is certain to be inefficient in other respects, for many of the shortcomings in design that make necessary the excessive use of labor are generally not corrected merely by having too many men. A simple example of this is a poorly designed ore-feeding system : if this is inadequate to the extent that one man must be constantly unclogging feed chutes, it may help the situation to put two men or three at this task instead of one, but the feed rate will still be inconstant. First of the factors that affect labor saving is the location of the mill. This is often determined by transportation costs alone, and as a result the mill may be placed close to the mine regardless of the nature of the terrain. The designer must then adapt his layout to the conditions, favorable or not. This happens often at small properties, where capital investment may seem more important than operating expense. In most instances, however, a mill site carefully selected for the advantages it gives the designer in laying out the plant is the most economical in the long run, even if it involves a slight increase in cost of ore haulage. Given some freedom of choice, the design engineer may be able to find just the piece of ground that provides the proper gradient for the needs of the flowsheet, permits installation of essential yards and trackage, and perhaps supplies an excellent site for a tailing dam. Further justification for having placed the mill not too close to the mine sometimes emerges only years later as an opportunity to treat ores from other properties. When it is known from the beginning that the new mill will serve a number of scattered mines, a free choice of mill site is naturally stimulated. The most important single factor in limiting the labor requirements of a mill is its materials-handling system for bring-

Jan 1, 1947

By Norman Weiss

The need for more efficient utilization of labor in the metal-mining industry has been the subject of several recent editorials in the mining press, and one attractive possibility for such improvement lies in the designing of future milling plants particularly with economy of manpower in mind. We are accustomed to think of mill design as the selection and coordinated arrangement of process equipment, but if labor is to be efficiently utilized it must be given early consideration in planning the new mill. There are three good reasons for economizing in labor: (I) to reduce costs, not only in the form of wages but also in housing, hospital, welfare, and other obligations that a company accepts when a new man is added to the payroll; (2) to prepare for recurrent periods of manpower shortage, during which a well-designed plant can manage to get along with skeleton crews; (3) because a milling plant that must depend upon an inordinately large labor force for its operation and maintenance is certain to be inefficient in other respects, for many of the shortcomings in design that make necessary the excessive use of labor are generally not corrected merely by having too many men. A simple example of this is a poorly designed ore-feeding system : if this is inadequate to the extent that one man must be constantly unclogging feed chutes, it may help the situation to put two men or three at this task instead of one, but the feed rate will still be inconstant. First of the factors that affect labor saving is the location of the mill. This is often determined by transportation costs alone, and as a result the mill may be placed close to the mine regardless of the nature of the terrain. The designer must then adapt his layout to the conditions, favorable or not. This happens often at small properties, where capital investment may seem more important than operating expense. In most instances, however, a mill site carefully selected for the advantages it gives the designer in laying out the plant is the most economical in the long run, even if it involves a slight increase in cost of ore haulage. Given some freedom of choice, the design engineer may be able to find just the piece of ground that provides the proper gradient for the needs of the flowsheet, permits installation of essential yards and trackage, and perhaps supplies an excellent site for a tailing dam. Further justification for having placed the mill not too close to the mine sometimes emerges only years later as an opportunity to treat ores from other properties. When it is known from the beginning that the new mill will serve a number of scattered mines, a free choice of mill site is naturally stimulated. The most important single factor in limiting the labor requirements of a mill is its materials-handling system for bring-

Jan 1, 1947

By Anthony G. Reid

INTRODUCTION At the time of the death of Mao Tse-tung in 1976, China was a major oil producing country with a daily oil flow in the order of 1.735 million barrels. This position had been achieved with minimal assistance from the outside world. Further, only some fifteen years had elapsed since the country's daily oil production capacity had hovered at the barely significant level of one hundred thousand barrels. Why then did the new leaders of China, after this very creditable record of success, suddenly change the direction of the country's drive for future hydrocarbon production? First, by switching much of the emphasis of exploration from onshore to the offshore continental shelf basins, and further by apparently abandoning the philosophy of self reliance calling upon the world's oil industry to share in the task of locating and developing these potential offshore energy reserves. The answer is probably only partly understood by those of us outside China, However, a number of factors exerting an important influence on this decision can be identified. THE MOVE OFFSHORE The new leadership was anxious to rapidly move China into her rightful place amongst the powerful and technologically advanced nations of the world. Modernization became the slogan, specifically modernization on four fronts, agriculture, industry, technology and military with the goal to "catch the west by the year 2000". But how to generate the capital to finance this massive modernization program? The rapid escalation of the price of crude oil following the 1973 Oil Embargo and the continuing apparently insatiable world demand for this now extremely precious primary resource was very clear to all. China, as a major producer, could export crude to help finance the ambitious development programs of the government. To do this, however, would require a very significant in¬crease in present production capacity, as the domestic demand even for China with her relatively low per capita energy consumption, is essentially equal to the current production. Trying to rapidly move the new regime's programs into actions, one can only assume that the planners looked at the success of the petroleum industry over the preceding fifteen years and quickly concluded that this well established curve could be maintained and indeed steepened with an increase in effort. The rapid discovery of a few more Daqing's (China's premier oil field, producing one million barrels a day) would have the country's ambitious modernization goals within reach. Petroleum would At the time of the death of Mao Tse-tung in 1976, China was a major oil producing country with a daily oil flow in the order of 1.735 million barrels. This position had been achieved with minimal assistance from the outside world. Further, only some fifteen years had elapsed since the country's daily oil production capacity had hovered at the barely significant level of one hundred thousand barrels. Why then did the new leaders of China, after this very creditable record of success, suddenly change the direction of the country's drive for future hydrocarbon production? First, by switching much of the emphasis of exploration from onshore to the offshore continental shelf basins, and further by apparently abandoning the philosophy of self reliance calling upon the world's oil industry to share in the task of locating and developing these potential offshore energy reserves. The answer is probably only partly understood by those of us outside China, However, a number of factors exerting an important influence on this decision can be identified. THE MOVE OFFSHORE The new leadership was anxious to rapidly move China into her rightful place amongst the powerful and technologically advanced nations of the world. Modernization became the slogan, specifically modernization on four fronts, agriculture, industry, technology and military with the goal to "catch the west by the year 2000", But how to generate the capital to finance this massive modernization program? The rapid escalation of the price of crude oil following the 1973 Oil Embargo and the continuing apparently insatiable world demand for this now extremely precious primary resource was very clear to all. China, as a major producer, could export crude to help finance the ambitious development programs of the government. To do this, however, would require a very significant increase in present production capacity, as the domestic demand even for China with her relatively low per capita energy consumption, is essentially equal to the current production. Trying to rapidly move the new regime's programs into actions, one can only assume that the planners looked at the success of the petroleum industry over the preceding fifteen years and quickly concluded that this well established curve could be maintained and indeed steepened with an increase in effort. The rapid discovery of a few more Daqing's (China's premier oil field, producing one million barrels a day) would have the country's ambitious modernization goals within reach. Petroleum would be the principal bridge to the bright future. The next decision involved the question of where to look for these vast new reserves. Chinese exploration teams had already looked at most of the onshore sedimentary basins and, while they were the first to admit that there was much yet to do, it was fairly clear to them that the potential for large new accumulations was confined to two areas: the little explored, remote, inhospitable regions of western China, principally Xinkiang Province and the equally unexplored offshore basins of the continental shelf and slope. In both cases China faced a very serious problem. The inhospitable environments were severely straining her petroleum industry's current technological ability to cope, particularly as the government needed rapid results. Thus the pragmatic and, to the foreign oil industry, unexpected decision to invite cooperation with the outside world. The reasons for the initial emphasis on the exploration of the offshore basins with the cooperation of foreign oil companies are again supposition on my part, but probably involved considerations of technical merit, ease of development and delivery to markets together with more sensitive issues such as controling the influence of foreign philosophies and values on the Chinese population by containing most foreign activity to the offshore. So within three years of the death of the great helmsman, China had developed a plan to involve foreign oil companies, both state and private, in a grand plan to rapidly increase the nations oil production. In fact, by this time, the first round of talks had been concluded and the first phase begun, and what a beginning. Some forty eight companies from thirteen countries had signed documents to participate formally in this world scale event. It was far easier to list those companies which did not participate than to list those which did. FOREIGN COMPANY INTEREST Why the rush by the world's oil industry to be involved in China? What was China offering which made everyone so anxious to join in? Again the answer is complex in detail, but principally involved a combination of factors which together caused this virtual stampede. Timing was a major element. Oil Companies, despite an ever increasing take by governments, were beginning to benefit. from the' rapid escalation of crude prices induced by OPEC and were looking for suitable areas to reinvest these funds. Producers

Jan 1, 1982

Richard Moldenke, New Pork, N. P. (communication to the Secretary*):—Iu following the discussion of the specifications for cast-iron and finished castings, I mas strongly impressed with two points which might be ventilated to advantage more fully from the view of the practical foundry-man. First, the reasons why only silicon and sulphur were specified and not phosphorus, manganese and carbon; and second, why but little was said concerning the presence of iron oxide in the material.

Jan 1, 1905

By C. A. Allen

FOR over three years we have been endeavoring to reduce the number of fatalities and minor accidents in Utah. The physical condition of the o? Represents the average of 4 States mentioned excluding the catastrophes indicated. FIG. 1.-NUMBER KILLED PER MILLION SHORT TONS OF COAL PRODUCED IN COLO¬RADO, NEW MEXICO, UTAH, WYOMING, AND BITUMINOUS MINES OF THE UNITED STATES, 1914 TO 1920. mines, concentrators, and smelters is good, yet the number of accidents,

Jan 5, 1922

By W. Julian Parton

General Crushed Stone Co. operates a dozen quarries in such rock types as gabbro, basalt, granite and limestone. Drilling characteristics and problems vary from one operation to another so that a variety of equipment and methods must be employed. In addition, it has been found that equipment improvements make it advisable to continuously look for and experiment with new machines and accessories. This article discusses drilling progress at some of the Company's more interesting operations.

Jan 1, 1963

By S. FROES ABRUE

No new oil fields were discovered in Brazil during 1945. Production for the year reached a total of 79.329 bbl., all coming from the four fields in the Baia basin; the Lobato-Joanes field produced 6728 bbl.; Aratu, 6717 bbl.; Candeias, 36,663 bbl. and Itaparica, 29,211 bbl. The total cumulative production from the Baia basin from 1939 to 1945 inclusive amounts to 210,000 bbl., all of which is utilized locally.

Jan 1, 1946

By John M. Rayburn

When plans were made for the new mine of the Allegheny-Pittsburgh Coal Co., Springdale, Pa., it was decided to operate on the room and pillar system, but not to have any extensive room development, the pillar work being done altogether on the retreat. On each room heading five rooms were to he driven advancing, while five pillars were being removed, so timed as to form a continuous pillar line, with all approaching

Jan 1, 1930

By D. J. Spottiswood, C. N. Robinson, D. E. Spiller, E. G. Kelly

This paper describes the performance of a new design of spiral that is optimized for fine coal cleaning. Reduced Performance (Tromp) curves are presented to compare this spiral with the older design, as well as with other commonly used coal cleaning equipment. As an aid to equipment selection and circuit design, data are also presented to show how variables, such as flow rate, pulp density, and particle size, affect efficiency and the separation specific gravity.

Jan 1, 1985

The work of Americanism is getting under way slowly but surely. The purpose of the Auxiliary is to build for all time and it therefore wishes to lay its foundations securely, feeling that the true understanding and adoption of the ideals of Americanism are the safeguards of our country from the perils of anarchy, and the bond of union between labor, brains, and capital. We hope to have reports from several directors to print next month and here append the report of the Director for the New York Section, Mrs. W. Y. Westervelt.

Jan 5, 1919

ARTHUR F. BRAID,* New. York, N. Y. (written discussion ?). -I have read Mr. Cain's paper with a very great deal of interest. The subject is one that is worth a great deal of thought and research at this time. It is a well-known fact that the strong affinity of steel or, iron for oxygen is perhaps the main detriment to sound production, and, as the author states, it is-indeed remarkable that today there are no analytical methods in general use in steel works for determining the gaseous con-stituents of steel.

Jan 10, 1919

By John Gillie

Prior to the year 1902 electricity was used in the Butte district only for lighting, for the tramming of ores on the surface, and for the electrolytic refining of copper. In that year the Canyon Ferry hydro-electric plant on the Missouri river, with a transmission line to Butte and Anaconda, was completed, and enabled the mining operators to purchase electric current in large quantities at reasonable rates, and its application and use in the various mining operations and reduction works proceeded rapidly. The principal applications. of electric current in metal mining may be listed as follows: Compressing air for hoisting. Compressing air for rock drills and pneumatic tools. Pumping. Ventilating. Lighting. Tramming. Compressing air for blast furnaces and converters Running shop and miscellaneous motors.

Jan 9, 1913

By AIME AIME

AT a recent meeting of the Utah Section. A.I.M.E., P. D. Nielson, general plant superintendent of the new Geneva steel plant at Provo, Utah, spoke on "General Operations of the Geneva Plant." Mr. Nielson explained that the plant was located at Provo, Utah, on account of railroad facilities, the proximity of coal, iron, and limestone, and the nearness of water for operating the plant. Water probably was the most important item in making the decision.

Jan 1, 1944

By Wilbur C. Helt, Joseph J. Yancik

Throughout the history of mankind, the principal use of coal has been to produce heat through combustion. The heat is used in many ways: to warm air space for our comfort; to provide heat or energy to power industrial processes, such as cement and steel production ; and to produce electricity. Because it is our nation's most abundant fossil energy fuel, coal in the late 20th century is on the threshold of becoming a significant source for synthetic liquids and gas energy fuels for this country. This is made possible by conversion processes which can change solid coal into various synthetic gases and liquids. These coal-derived fuels are nearly identical to the processed fuels and chemicals provided by natural gas and crude oils, which presently provide almost all the petrochemical feedstocks and energy fuels needed for the residential, light commercial, and transportation markets. A revolution is beginning to take place, not only in the United States, but in many other countries with a return to a coal-based energy economy. Also, new combustion and conversion technologies which are compatible with national health and environmental goals are rapidly emerging. These technologies will allow coal's use to be expanded not only in its traditional markets, but also to supply markets held by natural gas and crude oil. With the worldwide decline in natural gas and crude oil reserves, coal is being looked upon to meet the energy demand. Because of these new coal conversion technologies, coal will no longer be only a combustion fuel, but a valuable raw material for production of a variety of clean fuels and chemicals. MARKETS FOR COAL: PAST AND FUTURE A simplified diagram of the marketing network for coal is shown in Fig. 1. As shown in this figure, coal is transported to its traditional

Jan 1, 1981

By David B. Scott

The Mogollon mining district, New Mexico, has received little public attention, although for 15 years it has been the leading silver producer of the state; it is situated in a region remote from the principal lines of travel, and its activities have usually been limited to the operations of two or three companies. The value of the total production of the district in the 44 years of its history has been estimated at $15,000,000. For the years 1904 to 1917, inclusive, the output was: gold, $4,370,000; silver, 10,042,000 oz.; copper, 874,862 lb.; total value, approximately $10,500,000. In 1913 the district contributed 80 per cent. of the total silver production of New Mexico, but in 1917 only 41 per cent., due to serious interruption in the operations of the leading producer. Since 1914 the silver output has diminished one-half, and the present high value of silver is nearly offset by the increase in cost of production. The output of gold has rarely exceeded 35 per cent. of the total for New Mexico. The ratio of silver to gold, by weight, has averaged 46:1 based on the whole output of the district. Location and Topography The town of Mogollon is 75 mi. (121 km.) by a poorly located highway ,. from the nearest railroad terminals, at Silver City and Tyrone. All supplies are transported by motor trucks and teams. The area, sometimes called the Cooney Mining District, lies on the western flank of the Mogollon Mountains, which occupy the western part of Socorro County. The elevations drop steeply on the west to the valley of the San Francisco River, adjacent to the Arizona boundary. The topography is very rugged, the whole area being sharply dissected; deep canyons with steep gradients and rugged walls are characteristic of the whole western slope of the Mogollon Range. The main canyons i run east and west, and usually maintain a flow of water during the entire year. As would be expected in a region of such deep dissection, the mines are generally dry. The mountain ridges between the canyons have altitudes varying from 7000 to 10,000 ft. (2130 to 3050 m.) and drop sharply, on their western face, to the floor of the San Francisco Valley at an elevation of 5000 ft. (1525 m.). Erosion has been rapid, and the

Jan 1, 1920

By Kenneth A. Moon

Kenneth A. Moon (U.S. Army Materials Research Agency)—The authors are to be congratulated for a very interesting and valuable paper. Their discussion of the structural implications of the results shown in their Fig. 5, however, requires a small correction. The model of Speiser and Spretnak with 0 = 1 and z' = 2 is perfectly reasonable for the Ti-O a phase, but Eq. [3] is valid only for solutions sufficiently dilute that the number of empty sites excluded by more than one filled site is negligible. The composition at which intrinsic saturation occurs therefore cannot be deduced from Eq. [3], but but must be decided by consideration of the structural details of the phase in question. In this case, intrinsic saturation is expected not at the composition Ti3O but at Ti2O, because Ti2O has the anti-Cd structurel4 for which each filled octahedral site has two nearby empty sites, one in the hexagonal plane immediately above it, and one in the similar plane below it. The other two models, with ?=1/3 and 1/2, imply a distinction between octahedral sites in pure titanium which is not easy to justify. The problem of extending Speiser's and Spretnak's treatment in a general way to more concentrated solutions will be the subject of a forthcoming publication by the writer. M. T. Hepworth and R. Schuhmann, Jr. (authors' reply)—The authors wish to thank Dr. Moon for calling to their attention the paper by Holmberg which presents the results of X-ray studies of Ti-O solutions ranging from 0 to 33 at. pct 0 and quenched from various annealing temperatures between 400" and 1800°C. Within these ranges, Holmberg found three types of phases: 1) At high oxygen contents (above 25 at. pct) and low annealing temperatures, he found the anti-Cd(OH)2 structure referred to by Dr. Moon. In this structure each titanium atom is in contact with 3 oxygens and each oxygen is in contact with 6 titaniums, the "available" oxygen sites corresponding to every other layer of octahedral sites in the titanium matrix. The limiting composition is Ti2O. However, this anti-Cd(OH)2 structure was not observed for samples containing 25 at. pct 0 or less. 2) For the specimen containing 25 at. pct 0 annealed at 400°C an ordered Ti3O structure was observed. This structure is related to the anti-Cd(OH)2 structure but differs from it by providing only two oxygens adjacent to each titanium atom and thus is consistent with the model represented by Eq. [5] in our paper, with 6 = 1/3, z' = 0. 3) For dilute solutions and for more concentrated solutions annealed at higher temperatures, the structure corresponds to that of the metal with random distribution of oxygens among all the octahedral sites. Thus, it is interesting to observe that the thermo-dynamic indications of ordering in the vicinity of Ti3O can now be supported qualitatively at least by Holmberg's X-ray evidence of the existence of an ordered phase of the composition Ti3O. That is, for solutions with oxygen contents close to that of Ti3O, both the thermodynamic data and the X-ray data are more consistent with models based on the ordered structure of Ti3O than they are with the model which Dr. Moon suggests corresponding to "intrinsic saturation" at Ti2O.

Jan 1, 1963

By Wayne E. Glenn

The San Miguelito Field of Ventura County, California, lies along the coast approximately five miles northwest of the city of Ventura. The structure is one of several in the Ventura anticline, a series of anticlinal folds trending northwest-southeast through the San Miguelito Field. The Ventura Avenue Field lies to the southeast along the anticline, and Padre Canyon and Rin-con Fields lie to the northwest; the series then extends beneath the Pacific Ocean. Production is obtained from the Lower Pico and Repetto formations of Pliocene age, and oil accumulation is controlled by faulting, lithology and structure. The first well in the First Grubb Pool was completed in November, 1931, and to date 48 producing wells have been drilled on the 276 productive acres. Approximately 685 ft of net pay are contained in the eight sand bodies grossing 1,220 ft of section. Production of oil to date has been 15,-600,000 bbl. A gas injection project was instigated in April, 1940, but was discontinued in September, 1949. This paper is confined to a discussion of the development and performance history of the First Grubb Pool of the San Miguelito Field. LOCATION AND GEOLOGY The San Miguelito Oil Field is located in Ventura County about five miles northwest of the city of Ventura along the coastal highway to Santa Barbara. It is located within sections 23, 24, 25, and 30 of Township 3 North, Range 24 West, San Bernardino Base and Meridian. Surface elevation in the field ranges from sea level to plus 1,200 ft, and the terrain is extremely rugged. The structure is well defined on the surface and on the wall of the Amphitheatre Canyon where appears a so-called "text book" anticlinal section. The San Miguelito structure is an asymmetrical, elongated anticline about two miles long and three-fourths of a mile wide. The trend of the axis of the anticline is northwest-southeast. Fig. 9 illustrates the contours and major faults of this structure. Dips on the southwesterly flank average about 40 degrees, whereas the northeasterly flank ranges from 60 to 75 degrees. There are several faults striking generally east and west. These faults do not appear to affect materially the area of accumulation or performance behavior. It is believed that accumulation was affected by steeply dipping beds and extremely low permeability of the northeast flank of the structure. As shown by the typical log, Fig. 1. the San Miguelito Field is divided into two stratigraphic producing intervals. The First Grubb Pool comprises the interval from the "G" to "L" markers; the Second Grubb Pool from the "L" to "M" markers. The First Grubb Pool, ranging in thickness from 1,105 to 1,680 ft, with an average of 1,220 ft, includes approximately 685 ft of oil-bearing sands. The First Grubb zone consists of eight sand intervals separated by shales. The shale bodies separating the eight sand intervals within the First Grubb Pool are continuous throughout the major part of the structure and serve as an effective barrier. Many of the thin, irregular shale or siltstone streaks within these sand bodies are discontinuous and do not affect well performance appreciably. The productive horizons in the First Grubb Pool are siltstones and sandstones of the Lower Pico and Repetto formations of Pliocene age. It is apparent from inspection of the typical log that the "G" to "L" interval might have been separated into at least six producing zones and selectively pro. duced. Unfortunately the electric log and some of our modern tools were not available or were in their infancy dur. ing the period 1931 through 1937. Not until 1937 when eight wells had been completed were there sufficient geological data to permit definition of the sand bodies. Then the problem of reservoir control in this multiple-sand field, where all sands are open to a common

Jan 1, 1950