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By John R. Bogert

The title of this session is "Wall Street Looks at the Mining Industry," and I am going to attempt to answer the question: Shouldn't Mining Stocks Sell at Higher Price Levels? Or, What Does Wall Street See When Looking at the Mining Industry? Well, it sees a capital intensive business, a technical industry, and a growing industry becoming more vertically integrated. But, at the same time, Wall Street sees a cyclical industry, a fragmented industry of erratic earnings, spotty public relations, a feast-or-famine business where the public usually does not differentiate between coal mining or metal mining, and does not appreciate either the risks or the rewards. As a result, mining stocks generally sell at relatively low price learnings ratios in comparison to other industrial groups. This PIE ratio, the current market price of the capital stock divided by annual earnings per share, is probably the most popular index of a stock's value. The average of the price/ earnings ratios of the 30 stocks comprising the Dow Jones Industrial Average is over 14. This diverse group of stocks is widely regarded as being a cross-section and representative of the industrial companies listed on the New York Stock Exchange. However, in comparison to 14, Asarco and Kennecott shares are currently available for about 8 times annual earnings. Even discounting earnings from South America, the stock of these two companies sells at only 10 times earnings. Of course, Peruvian politics is currently preventing Cerro shares from selling above 6 times earnings, and Chilean politics keeps Anaconda shares at a PIE multiple of 7. However, even in better times, these companies rarely sell above 10 times earnings. American Metal Climax and Newmont sell at only 11 times earnings as does Phelps Dodge and St. Joseph Lead. Few mining companies then have what can be considered a high PIE ratio-a figure higher than

Jan 1, 1970

By C. T. Wallace

Evans Industries, Inc., a management coal consultant and company was assigned to evaluate National Steel Company's coal properties in Knott and Floyd Counties, Kentucky. The results of evaluation showed large reserves of good quality, high volatile metallurgical coal contained in the Elkhorn coal beds and resulted in the formation of Beaver Creek Consolidated Coal Company. Based on results of the exploration and feasibility work, the decision was to install a coal nine, preparation plant and related facilities having a production capacity of one' and three quarter million tons per year with Evans Industries acting as Beaver Creek's management company. The recoverable tonnage assigned to the Stinson Mine is approximately forty-five million tons. This paper discusses the general arrangement of storage, conveying, loading, refuse disposal facilities and the flow sheet of the preparation plant developed by engineers of Heyl & Patterson, Inc., and Evans Industries, Inc., with emphasis on practical flexibility, sulfur reduction in all circuits, and high product yield with the minimum amount of selective mining, Three and one-half miles of railroad have been built by the Chesepeake & Ohio Railroad to service this mine.

Jan 1, 1970

By V. Niemitz

Approximately 30 miles east of Chicago on the southern shores of Lake Michigan stands Bethlehem Steels newest fully integrated steelmaking facility-the billion dollar Burns Harbor plant. The first phase of what will ultimately be the most completely integrated and flexible materials handling system for a steel mill in the western hemisphere is now complete.

Jan 1, 1970

By M. J. Marcinkowski, K. S. Raghavan, A. S. Sastri

A detailed transmission electron microscopy investigation was carried out in connection with a manganese Hadfield Steel. At small plastic strains, numerous individual intrinsic stacking faults are observed. With increased plastic deformation, the stacking faults thicken into twin lamellae which in turn subdivide the original austenite matrix into smaller domains. The twin boundaries act as strong barriers to subsequent dislocation motion and is in a sense equivalent to grain refinement. It is this "grain refinement" which is believed to be the cause of the very high work hardening rates in the Hadfield Steels. In many cases, especially where an hcp phase is the stable one at low temperatures, the stacking fault energy in fcc metals and alloys decreases with decreasing temperature.' Since stacking faults of the intrinsic type are precursors of both twins as well as the hexagonal close packed structure, both of these entities should become more frequent as the temperature of a fcc crystal is lowered. In the case of the twin, there is no chemical driving force for its formation and it is generally necessary to provide the required driving force by an applied stress, i.e., strain energy. In the case of the hcp structure the transformation from the fcc modification can occur spontaneously (marten-sitically) since a decrease in chemical energy does in fact occur; however, an applied stress will provide an even greater driving force toward complete transformation. Since the transformation products mentioned above occur in an inhomogeneous manner throughout the crystal and since these can act as potential barriers to further plastic deformation2 marked strengthening effects can be anticipated. Also because metal and alloy strenghening is in general proportional to the shear modulus, these effects should be greatest in steels of the austenitic type (y), i.e., the fcc types. Perhaps the two most important steels in this category are the austenitic stainless steels and the Hadfield manganese steels. Both may be quenched from elevated temperatures so as to retain the austenitic states characteristic of those temperatures. The effect of subsequent deformation at lower tem- peratures has a profound effect on the stress-strain curves of these alloys. In particular Fig. 1 shows the compressive stress-strain curves obtained with an 18-8 stainless steel which was quenched from 1850°C after annealing for 1 hr so as to produce all y. As the temperature is lowered, the work hardening rate increases markedly. Although some hcp or c mar-tensite can be generated by plastic deformation as the temperature is lowered,~ it is believed to be a transition phase4 and most of the martensite produced is of the bcc or a variety.3 It is this stress induced martensite which gives rise to the very low initial work hardening at 77°K as can be seen in the stress-strain curve in Fig. 1. Similar low initial work hardening rates have been observed in the stress induced Ni-Ti martensites.5 Fig. 2 shows that an even more rapid rate of work hardening occurs in the Hadfield steels treated in the same way as that described for the 18-8 stainless steels a; the temperature is lowered. It is this ability to work harden to such high stress levels that makes the Hadfield steels particularly suitable for armor plate and heavy construction equipment. However, unlike the case of Fig. 1, no initial low rate of work hardening is observed in any of the curves in Fig. 2. Thus the stress induced formation of any low energy martensite phase in any significant quantity must be ruled out. This observation is in accord with the X-ray findings of Otte.~ On the other hand, small quantities of the E phase have been observed by other investigators using transmission electron microscopy (TEM) above Even more significant was the fact that large numbers of deformation twins were observed in the deformed Hadfield steels,678 which were postulated to be one of the reasons for the high work hardening ability of this class of steels.8 It is the purpose in what follows to discuss a series of experimental observations pertaining to the stress induced transformation in a Hadfield steel and to formulate a dislocation mechanism which adequately accounts for the observed results. EXPERIMENTAL PROCEDURE The stainless steel used to obtain the curves shown in Fig. 1 was of the AISI Type 303 containing approximately 18.0 pct Cr and 8 pct Ni. On the other hand, the Hadfield manganese steel used to obtain the curves shown in Fig. 2 contained between 1.00 to 1.25 pct and 11.5 to 13.5 pct Mn. In all cases the samples were in the form of compression cylinders 0.220 in. in diam and 0.370 in. long. Prior to testing the samples were annealed for a hr at 1050°C and rapidly quenched into a brine solution. This treatment was sufficient to preserve the y phase for subsequent testing at lower temperatures. All samples were compressed in an Instron testing machine using a cross head speed of 0.02 in.

Jan 1, 1970

By Freeman Bishop

Having obviously cleared the way for fast confirmation by the Senate Interior Committee, the Administration recently named Elburt F. Osborn, vice president of Penn State University, as director of the Bureau of Mines. Interior Committee Chairman Henry M. Jackson (D of Wash.) has moved hearings on the nomination right along, forecasting that they will end in a confirmation. Dr. Osborn not only made a good impression on the Committee, he also made it amply clear that he would be the boss of his job and have right-hand aides to help straighten out conflicts stemming from recently enacted health and safety regulations for miners. Mining engineers in the field hope this clarification can come soon. They are frankly fed up with local, state, regional and national overlapping of restrictions.

Jan 1, 1970

By Richard J. Robbins

Mechanical moles have developed through a tedious process of evolution. At times it has seemed that tunnel borers have been subject to the same Darwinian rules of evolution as their zoological namesakes who, despite their efficiency, are highly specialized and still restricted to soft soil conditions near the surface of the ground. HISTORICAL HIGHLIGHTS The Robbins Co. began its work in this field in 1947 with the development of a twin-bore continuous coal miner. Although these machines were used primarily in coal, two of the early prototypes were used to bore tunnels through shale. Disk cutters were first used on these machines and showed promising results as core breakers between drag-bit kerfs. In 1953, James S. Robbins and Assocs. undertook the development of a 25-ft 9-in.-diam circular tunnel borer for Mittry Construction Co. to be used at Oahe Dam in South Dakota (Fig. 1). This is believed to be the first rock tunnel-boring machine built since the end of the 19th century when short sections of the Channel tunnel were successfully bored in chalk from both the English and French shores. Another Oahe Dam machine was built in 1955, and then a series of three small-diameter machines for the company's first real experience with medium-hard and hard rock (Fig. 2) None of these three could be considered a success, although they laid the groundwork for the success that followed. Interbedded shale and limestone in Pittsburgh and hard limestone in Chicago quickly pointed up the weaknesses in these machines which were used by Perini, Dravo, and Healey. Among the problems were the high breakage rate of tungsten-carbide drag bits, too much flexibility in the drive shafts, failure of high-pressure hydraulic systems, chain-conveyor failure, and general lack of rigidity and strength. In 1956 another attempt at medium-hard and hard rock-boring proved this time to be a success and a significant turning point in the development

Jan 1, 1970

By Walter E. Lewis

Myriad problems face all of us in the next decade. Vietnam, poverty, and pollution are perhaps the most pres- sing. A lesser one but still vital to us as a Nation is the slow hut apparently relentless extinction of the mining, metallurgical. geological and petroleum engineer. Are we doomed to take our place in the crossword puzzle with the moa. to be defined like it as an "extinct bird"? Or can we reverse the trend perhaps, in the next decade? The plain fact is we are an endangered species, and must resign ourselves to virtual extinction in the 1970's unless the trend is reversed. Probably, many of us have felt the problem will solve itself if left in the in-basket long enough, believing, that the trend will reverse solely on the basis of demand for these disciplines. This approach has not worked up to now, it gives no promise of working in the future, and furthermore, the problem has been in the in-basket much too long. The point is simply this: What can each of us do as an individual, or as part of a company, a State agency, a Federal agency, a university, or an organization such as AIME?

Jan 1, 1970

By A. D. LeClaire

This paper claims to provide a description of diffusion processes in solids which is said to be a reformulation of Fick's Laws and therefore, presumably, is supposed to be as general as those laws. In fact, it appears to provide no more than an atomic model of a rather restricted type leading even to results in conflict with experiment. The restriction lies in the assumption, carried throughout the paper, that even in a chemical gradient the jump frequency i of an atom of species i is a function only of the composition on the plane from which it jumps, i.e., ?i = ?i(cl, c2 ...). This means that atom jumps in opposite directions from a site would occur with equal probability. There would then be no tendency for atoms to migrate preferentially in one direction along the gradient, so the model is incapable of accommodating the well established phenomenon of atom drift in a chemical gradient.10-" A more general model that does not suffer this difficulty was discussed in a paper13 I wrote in 1958, and the results therein already contain as a special case those given by Dr. DeHoff. The simplest sufficiently general assumption is to suppose that ?i is a function ?i(a1 a2,...; wl, w2, ..-) of the concentration aj and ? ?j at the site from which and to which, respectively, a jump is made. Any such function can always be expressed as a function of the sum and difference of its arguments. Thus d is the jump distance and g a geometrical constant. Obviously this is zero, i.e., no drift, if ??ri/??j = 0. X is written in this form, revealing two components of the total drift, because it can be shown that only the second component, depending on ??'i/???(?j -aj), actually contributes to the net diffusion flux Ji. This component can be shown,13 by a straightforward ther-modynamic transcription, to be responsible for the so called "thermodynamic factor" in the Darken approximation for a chemical diffusion coefficient is the activity coefficient of i. Because the jump rate ?i in DeHoff's approximation has no dependence on the concentration gradient it does not seem possible to derive the Darken equation from his Eq. [6] without the further rather arbitrary assumption that ?i = const ri. It is to be noted too that the author's derivation of Eq. [12] is only valid when ?i is in fact a function only of the cj at the plane from which the atom jumps—for only then is ci?i a unique function of position and therefore of A. Author's Reply R. T. DeHoff I am indebted to Dr. LeClaire for his penetrating discussion of my paper, "A Reformulation of Fick's First Law". I concede that it does appear initially that the relationship presented in my paper could be derived from the detail atomic model of random walk and atom drift presented in Dr. LeClaire's approach. However, there are some important differences in concept and viewpoint which deserve further amplification. Dr. LeClaire's description is penetrating, detailed, and fundamental. His approach describes an extremely complex phenomenon, the displacement of atoms in a multicomponent gradient, at a sophisticated level. For precisely these reasons, his analysis has not proved to be useful for experimental studies that have practical objectives. For example, in order to obtain the information required to complete the analysis of the jump frequency distribution in a ternary system, the following series of experiments would, I believe, be required: 1) chemical (gradient) experiments, covering the composition range;

Jan 1, 1970

By Lawrence F. Rooney

One of Edgar Allan Poe's stories that haunts my subconscious is the Masque of the Red Death. These days, whenever I join a group like this, especially during the cocktail parties, I see myself and others as those mythical swingers seemingly isolated from the plague. The world, but this country especially, has had a ball plundering, spending, and wasting its natural resources for 100 years. And, as in days of yore, it is fitting that we end this ball with spectacular fireworks: trips to the moon, so that our grandchildren, huddled in their caves along the Ohio, will better understand how it all began.

Jan 1, 1970

By Philip C. Tully

This bibliography contains 3,062 different citations to technical and scientific literature about helium and alpha-particles abstracted by 13 abstract service publications during 1963. Multiple subject classification has increased the total number of entries to almost 5,000. Helium citations are listed by 23 major classifications. The number of subclassifications has been greatly increased to minimize the time required for literature search. The use of automatic data processing has been extended in compiling the bibliography.

Jan 1, 1970

By Warren E. Morrison

The first major evaluation of the nation's raw materials prospects after World War II was completed by the President's Materials Policy Commission (Paley Commission) in 1952 and submitted to the President in June of that year, as a five-volume study entitled Resources for Freedom. The bulk of the report was devoted to an analysis of the past, present, and probable future of the Nation's mineral supply industries. The Commission's evaluation of the future situation regarding minerals was derived from its forecasts of the probable domestic demand for the major minerals in the 1970's. This demand analysis was made in the context of probable worldwide demand. Several crucial assumptions were made by the Commission's fore-casters. It was assumed in 1950 that the next 20 to 30 years would see no major wars and be a period of sustained economic growth. Another assumption was that the anticipated demand for raw materials must be supplied at essentially no increase in real cost in order to avoid crucial supply problems. The Commission's forecasts were derived within the context of the country's expected future rate of economic activity. The gross national product (GNP) growth to 1975 was derived from projections of the number of people in the labor force, hours of work, and an index of probable production measured per unit of labor input. It was believed labor hours would decrease and labor productivity would increase. The result was a forecast GNP growth rate of 3 percent.

Jan 1, 1970

By Philip C. Tully

[This bibliography contains 3,655 different citations to technical and scienfic literature on helium and alpha-particles, abstracted by 13 abstract service iblicatlons during 1964. Multiple subject classification increases the total number of entries to more than 5,800. Helium citations are listed by 22 major assifications, alpha-particles by 12]

Jan 1, 1970

By Jesse H. Auvil

In January of 1966, during the annual session of Georgia's General Assembly, Representative Paul E. Nessmith of Statesboro, Georgia, walked into my office and asked me what I thought of the advisability and feasibility of a law which would require the mining operators to reclaim their mined out lands. My answer to him was, as a one time mine superintendent and operator, that I probably would not think very highly of the added cost which reclamation would impose on the operation; but that since assuming the job of Chief Geologist and Assistant Director of the Georgia Department of Mines, Mining and Geology, and in retrospect, I could recommend it very highly, particularly in view of the increased pressure being applied by the Federal government along these lines. I stated then and still emphatically state that this sort of administration should be done on the State level rather than the Federal level. He asked me if I would conduct him on a tour through some of the mining country in which I had worked and to this I readily agreed. The result of this trip was that he was adversely impressed by the devastation which the mining operations had wreaked on that area of middle Georgia along the fall line known as the kaolin belt. Very little except talk was done for the remainder of 1966.

Jan 1, 1970

By J. C. Martin

A theoretical analysis of steam stimulation is presented for single sands. The analysis includes the effect of steam production and most of the effects of heat conduction. The results show the effects of a number of important variables on the performance of an idealized well under steam stimulation. Calculated responses are presented which indicate the effects of steam production, amount of steam injected, water production, formation thickness and formation damage. Results indicate that steam production can cause large reductions in the heat contained in the formation. This effect can be eliminated by drawdown control. Water production reduces the amount of oil produced during stimulation. The optimum amount of steam to inject depends on economic factors as well as the well response. In many cases, the increased temperature resulting from stimulation reduces oil viscosity near the well sufficiently to overcome the effects of formation damage even if the damage is not removed during steam injection. Calculated responses for thin sands are more favorable than anticipated. INTRODUCTION Little has been published on the theory of steam stimulation'-' despite the interest it has created and the wide variation in well responses. The results of the present analysis provide an insight into steam stimulation, and the methods employed provide a foundation for future work. Analyses presented in Refs. 1 and 2 are very limited and apply to gravity drainage conditions. Ref. 3 contains an analysis similar to the one presented here. The idealized models used and the assumptions made in Ref. 3 are different from those used in this paper. The analysis assumes that after steam injection has heated a small portion of the volume within the radius of drainage of a single uniform sand, a shut-in soaking period is allowed before returning the well to production. The effects of gravity, capillarity, transient pressure and water-sensitive sands are neglected. The injection and soaking times are assumed short compared to the stimulated production time. The initial temperature is assumed uniform; thus, the results apply primarily to first-cycle stimulation. The effects of gas production other than steam are neglected, and the water-oil ratio during production is assumed constant. Steam stimulation involves the simultaneous variation of the temperature, pressure and saturations. General mathematical equations for these variations are complicated and can be very difficult to solve. Simplified equations based on idealized models are used to reduce the mathematics sufficiently to allow approximate solutions to be obtained. DISCUSSION INJECTION An idealized model for which heat conduction is neglected is used to represent the behavior of a well during steam injection. The mathematics for this model is presented in Appendix A which also contains an approximate solution for the behavior of the no-conduction model. SOAKING During soaking, the well is shut in. Only the temperature, pressure and saturation distributions at the end of soaking are needed in the analysis. During soaking the heat is considered to be conducted in a uniform medium from an initially uniformly-heated circular cylinder confined to the producing interval. At the end of soaking the saturations and pressures are assumed to correspond to the cold zone. Analysis of the heat flow during soaking is included in the next section. The radius of the heated cylinder is calculated from the following heat balance (for constant quality steam injection). At the end of the soaking period it is assumed that little or no free gas is present near the well, and that the soaking period has been sufficiently long that the steam zone has had time to expand and the steam has condensed. The condition where there is no soaking is considered in the next section. PRODUCTION In this section, an approximate method is presented for solving the equations of heat and fluid flow associated with the production of oil and water during steam stimulation. Where initial pressure drawdowns are sufficient to cause steam to flow into the wellbore, steam production is assumed to occur within a short initial adjustment period (Appendix B). The production practices followed soon after the well is returned to production can have a large influence on the amount of oil produced during the stimulation cycle. Under most conditions, there is a period of time in which some or all of the water in the heated zone is converted into steam and produced. This flashing of hot water is caused by the pressure in the heated zone dropping below

By R. K. Zipf

A method is presented for creating realistic numerical models for practical coal mine ground control. The method includes procedures to collect the necessary mechanical input parameters from a geologic core log, procedures to set up a model and procedures to interpret calculation results. The input parameters come from a detailed geologic core log and extensive point load tests of estimate rock layer strength. A suite of material property input parameters is proposed which allow the user to go from core log to numerical model inputs. Rock bolt anchorage properties are also linked to the material properties of each geologic layer in the model. Following this procedure leads to very realistic calculations of the rock failure process and rock support system behavior. These calculations in turn enable realistic comparison of the effectiveness of alternative rock support systems.

By P. F. Gnirk, J. B. Cheatham

An experimental investigation has been made to study the effects of tooth angle and confining pressure on the force required for indentation of dry rock samples under confining pressure. In these experiments static single-tooth indentations were made on two standstones, a limestone, a schist and a slate under confining pressures of 5,000 to 15,000 psi. Sharp wedge-shaped teeth with included angles ranging from 30°to 105°were used. In all cases the force-displarenzent curves are approxinlately linear for rocks tested under confining pressure, as contrmted with the discontinuous curves obtained for silnilar rocks at atmospheric conditions. Photonzicrographs of thin sections through the craters indicate very little evidence of chip formation during indentation. In general the experimental data lie between calculated values for perfectly rough and perfectly smooth tooth-rock interfaces. INTRODUCTION The variables associated with ctrilling at depth are numerous and, in many instances, are not easity isolated and controlled. Also, many of these variables are interdependent; however, if the variables which are sufficiently independent of each other are held constant and are appropriately introduced, the dependent variables can be more easily studied and evaluated. It is the purpose of the present investigation to study experimentally the simplest case of bit tooth-rock interaction. In essence, the experiments have involved the static loading of sharp wedge-shaped tools on the surfaces of effectively semi-infinite dry rock samples subjected to confining pressures. During this investigation the following quantities have been maintained constant: 1. Pore pressure: atmospheric (i.e., the rock is dry). 2. permeability: although the rocks may be permeable, they are "jacketed" in such a manner that the fluid is not permitted to flow through them. 3. Temperature: 75F. 4. Rate of loading: essentially static (approximately 0.002 in./second). 5. Bit tooth: a sharp wedge-shaped tooth loaded normal to the rock surface. 6. Rock surface: smooth and flat. 7. Drilling fluid: hydraulic oil. In addition to the above conditions, the rock surface was free of a layer of cuttings. There was no indexing to previously indented surfaces, and the influence of corners of the borehole was neglected because the rock samples were effectively semi-infinite. The following quantities have been varied, and the resulting effects have been studied: 1. Rock a) Type (e.g., limestone, sandstone, etc.). b) Mechanical properties ) Necessarily dependent c) Porosity on type of rock. 2. Bit tooth (included angle of wedge-shaped tooth). 3. Depth of penetration. 4. cobfining pressure. On the basis of laboratory experiments which have shown that many rocks exhibit ductile behavior at confining pressures corresponding to depths usually reached during drilling,'.' a theory has previously been advanced which predicts the force required for penetration by a single sharp wedge tooth into a ductile* material.' The material is assumed to be isotropic, homogeneous and rigidly plastic (no elastic deformation) and to obey the Coubomb yield criterion (Figs. 1 and 2). Equations governing the force required for penelration are given for two extreme cases:** 1. A smooth, perfectly lubricated tooth-rock interface (fridionless boundary), in which the solution gives a minimum value for the penetrating force: in which F = force of the tooth, b = length of tooth edge,

By Amanda Azman, Richard Hi Danie/son

Ultimately, the most important product of a hearing conservation program is the prevention of hearing loss, not the amount of hearing protection that has been purchased or whether employees are attending their annual training sessions. Audiometric testing directly reveals whether hearing losses are actually occurring in a plant. With audiometric data, we can assess overall program effectiveness, alert workers of impending hearing loss, and reveal potential employer liabilities for compensable hearing loss. Without the ability to efficiently analyze audiometric data or produce effective reports, our programs become fruitless and unproductive. Consequently, ifaudiometric data are such vital end-products, then effective audiometric technologies serve as the prime architect and generator of these fundamental data. These technologies, consisting ofaudiometers, associated peripheral hardware, and database/reporting software, deserve our consideration.

By J. R. Elenbaas, J. A. Vary, D. L. Katz

The development of gas fields, oil fields and aquifers for storing natural gas is treated from two main vieu.-points: (I) the volumetric storage capacity for gas in a given situation and (2) the prediction of the number of wells required for the delivery of gas. Other experiences in the design and operation of storagc fields are incluclerl INTRODUC TION Storage of natural gas in underground reservoirs near the terminus of long distance pipelines has been the prime factor in opening the space heating market to the natural gas industry. Storagc has permitted a major. increase in both the load and the load factor of pipe-lines; some are now operating at steady load throughout the year. Thus, underground storage has been responsible for the rapid increase in demand for natural gas in recent years. Three types of reservoirs have been used for gas storage: natural gas reservoirs, oil reservoirs, and waterbearing sands or aquifers. This paper presents the factors to be considered when developing gas storage reservoirs of these three categories. There are two prime considerations tor any storage reservoir: (1) the volume of gas which a given reservoir will store advantageously and (2) the number 01 wells needed to provide the required peak deliverability. These two problems will be considered for the three types of reservoirs just noted STORAGE IN PARTIALLY DEPLETED GAS FIELDS Early storage operations consisted of replenishing the natural gas in a depleted gas field situated adjacent to the market. Today, newly discovered fields near the market may be considered for storage, and this discussion applies equally to both types of reservoirs. For reservoirs originally containing gas or oil, the question of the impermeability of the cap rock nor-mally does not arise. However, such fields are likely to have many wells drilled either to or through the reservoir under consideration. Positive assurance must be obtained that such wells are or can be made mechanically tight. Corroded casings may need to be lined or permanently plugged. Abandoned wells should bc reopened and properly cemented. The volumetric capacity for gas storage depends upon space available in the porous rock as well as pressure and temperature of the gas in the reservoir. The production-pressure decline data on partially depleted gas reservoirs without water drive permit calculation of the reservoir space for gas. Isopachous maps of sand volume and porosity data for the reservoir rock provide an alternate method of calculating the pore volume for water-drive reservoirs. The pressure range selected for the storage cycle depends upon ()) the safe upper limit of pressure. 2) the flow capacity of wells and (3) compression requirements when injecting gas into the reservoir or delivering to market. Normally, gas and oil fields have pressures at discovery in the range of 0.43 to 0.52 psi/ft of depth. Pressures of around 1.0 to 1.2 psi/ft of depth appear to lift the overburden1-3 and invite uncontrolled movement of fluids in the porous rock. Some top pressure is normally selected for a storage reservoir ranging from below discovery pressure for deeper reservoirs to 0.65 psi/ft of depth for shallower reservoirs. Pressures to 0.66 psi/ft have been experienced without difficulty. The lower pressure limit is set by water intrusion accompanying low pressures, reduced flow capacity for wells at lower pressures and compression requirements. Depletion-type gas reservoirs often encounter water problems in the later stages of gas production. Such water intrusion may be due to movement from the surrounding aquifer. Accordingly, displacement of this water back into the aquifer by gas pressure and subsequent surges of water corresponding to the gas storage pressure cycle must be considered. Storage fields often produce in four months a volume of gas equal to its initial content. Rapid decreases in reservoir pressure occur, such as 20 psi/day. Accordingly, closed-in pressure observation wells which reflect the pressure in the bulk of the reservoir are required for following the operation of the reservoir. It has been found that a plot of observation wellhead pressures against gas content, Fig. 1, is very useful in observing operation of the field, checking the inventory and predicting future behavior. The plot is based on a given quantity of base or cushion gas in place. The injection and withdrawal curves may spread depending upon the homogeneity of the reservoir rock. permeability of the rock, well spacing and flow rates.

By Jom Gentry

Acrylamide chemical grout (C3H2NO) has been successfully used for over 50 years to control groundwater and stop infiltration. This paper will address three unique projects involving the control of groundwater with each study providing special circumstances and geological conditions: encapsulation of radioactive hazardous waste in the United States, a tailings dam for a large copper/gold mine in Argentina and 27 miles of leaking subway in Canada. The primary reasons for selecting acrylamide grout were based on the following characteristics: thinnest chemical grout on the market, a true solution grout which contains no suspended solids in the blended product, flexible gel set times, and a 362 year half-life in soil as determined by the U.S. Department of Energy.