Search Documents

By R. G. Jones

Many novel projects suffer delays, cost overruns or failure because of inadequately qualified technologies. A new qualification to measure the quality of innovation is discussed.

Jul 1, 2015

By R. S. Hoch, Roy A. Bobo

Maintenance of desirable plastic flow properties of weighted drilling muds may be greatly simplified by use of centrifugal classification to control the drilled solids content. The new application of a decanting type centrifuge to separate and reject the low density solids from the weighting material results in a drilling mud of greatly improved quality with lower values of yield and rigidity. Its practicality and economy has been proven in field operation. The degree of separation of light and heavy solids is not limited by the machine, but by the particle size distribution of the solids in the mud. Removal of the low density component of drilling mud that makes chemical treatment necessary permits a marked reduction in chemicals. The main uses of the centrifugal process are the treatment of muds while drilling, the reclaiming of discorded muds, cleaning up of workover muds, and the reduction in lime content of mud for completion. INTRODUCTION Drilling mud in any circulatory system is made viscous and difficult to pump by gradual accumulation of drilled solids which pass through the shale shaker and are continually reground. In a weighted mud containing a large proportion of barite by volume, the amount of drilled solids that may be tolerated is greatly reduced. Much effort has been expended to control by chemical treatment the effects of such solids. Though chemical treatment is quite effective, the time eventually comes at deeper depths after enough drilled solids have entered the system when a portion of the mud must be discarded and replaced with water and more weighting material. Once begun, this process is generally continued at frequent intervals with resultant high maintenance costs. At the termination of drilling, mud highly contaminated with light solids and spent chemicals is poorly suited for completion operations.' It is likewise limited in utility for other drilling operations. This investigation was conducted for the primary purpose of determining an acceptable mechanical means of removing the lightweight solids from weighted drilling muds in order to maintain viscosity at a minimum. A decanting type of centrifuge was selected from the various possible methods of mechanical separation. The centrifugal process has been employed in this country for this purpose in central mud reclamation systems in California in earlier years. It also was used for treatment of weighted muds on the Gulf Coast.' In more recent years only sporadic attempts have been made to employ it in the field on weighted muds. DISCUSSION OF PROCESS Selection of Apparatus Two factors favor mechanical procedure for the separation and removal of drilled solids or clays from the mud circulatory system. First, the greater specific gravity, 4.1 to 4.3, of the barite would promote more rapid settling than the clays whose specific gravity range is from 2.5 to 2.7. Second, the relative coarseness of the barite particles also facilitate faster settling of this phase. A decanting type of centrifuge was preferred for this process over other possible methods for these reasons: 1. Requires no costly additives or excess dilution. 2. Centrifugal force affords greatly accelerated separation as compared to gravity.

Jan 1, 1955

By J. R. Cooper

Since man began beneficiating ores, a limited number of factors influenced the type of treatment. The ore itself has always been a factor. The first form of concentration was probably hand sorting, and the grade of concentrate and recovery had to be considered from the start. The cost of labor as a factor in mill design did not attain importance until the period following World War I. Power was one of the cheapest commodities available, and consequently power consumption was ignored. That no longer holds true. The present work does nothing to simplify the work of the metallurgist, or designer. On the contrary it adds another element to the design considerations. And while this report concentrates on power consumption, the mill designer must take the other factors into account as well. This study is based on a compilation of data supplied by a number of Western United States copper operations, as well as information from equipment manufacturers. Although its conclusiones apply to other minerals and geographic areas, the information is more precise, when applied to similar ores. The discussion has been divided into sections covering crushing, grinding, and flotation as these are the principal power consuming functions.

Jan 1, 1977

By R. Z. Pyrih

Uranium tailings at Cotter Corporation's Canon City, Colorado Mill were moved to a double-lined impoundment, but uranium and molybdenum salts remaining in the fractured bedrock underlying the old tailings ponds seeped into groundwater. Fluor Daniel GTI recommended an in situ geochemical fixation remedy, flushing Best Sulfur Products' calcium polysulfide reductant into the subsurface with clean water. Residual metals became immobile, trapped in the bedrock. Fluor Daniel GTI designed and implemented the process on ten acres with high metal concentrations. Cotter is operating and monitoring the system, which can be expanded to "hot spots." The original remediation time was estimated at less than five years.

Jan 1, 1998

By S. C. Sharma

The aluminium matrix composites with ceramic dispersoids can be separated by density difference concept. In the proposed work composite scrap is recycled using an oil fired furnace. The scrap is melted in the furnace and temperature is maintained below 740 degree centigrade. Because of the density difference the lighter dispersoids will float and heavier dispersoids will settle down. The clean melt is separated be removing the floating and settled disperssoils, and then filtering using ceramic filters.

Jan 1, 1995

By D. S. Parasnis

The early beginnings of mining geophysics in Sweden can be traced back to the reign of queen Kristina in the 17th century. The mine compass, consisting of a freely suspended magnetic needle in a casing, was in use certainly by 1640 and probably earlier for locating iron ore deposits. Whether the mine compass was a Swedish invention or not is an unsettled question since the possibility cannot be overlooked that the celebrated Nürnberg compass-makers of the 16th century may have constructed it for the first time(1). Be that as it may, the mine compass was very extensively employed in Sweden for more than two centuries and met with spectacular success in locating magnetic deposits under shallow overburden. Occasionally the diligent prospector would even be rewarded with a pyrrhotitebearing sulphide deposit, as witness many old sulphide-ore pits and some mines still in operation from the 17th and the 18th centuries. The mine compass measured only the orientation of the Earth's magnetic field and not its strength. Although it was improved in construction and sensitivity over the ages, no great strides were made in magnetic prospecting after the initial discovery of the use of the compass until Gauss, omnipresent in 19th century physics and mathematics, showed with the assistance of Weber how the strength of a magnetic field could be determined.

Jan 1, 1975

By J. F. Myers, R. J. Tower

"THERE is nothing new under the sun." All over the world, mineral-dressing engineers are working at their problems, no two of which are alike. Each encounters equipment and process problems. Many devise simple ways and means of overcoming their difficulties. Many of these problems are quite common in the industry, yet, since no one human being seems capable of thinking of everything, these problems at some plants often are looked upon as necessary evils. The purpose of this symposium is to gather together, from competent engineers, devices and practices that have been useful to them. Most of the ideas contributed are not new, yet there is no plant operator, old timer or youngster, who will not find some idea herein that will give him a suggestion for improving his operation. Space does not permit a complete elaboration on all of the contributions offered. Each item is summarized, but this will be ample for those skilled in the art of mineral dressing. A list of contributors appears at the end of the paper, and the superior number at the end of each item identifies its source. GENERAL EQUIPMENT A signal light to show that a steel bin, containing relatively fine, moist ore, is full, can be made by suspending a copper rod in the bin to a sufficient depth to ensure ample contact with the ore. One wire of a 32-volt circuit should be attached to the rod and one to the side of the bin. Sufficient current will flow to make the signal light burn. A 110-volt circuit could be used, but 32 volts ensures safety.10 Fig I shows a circular bin for crushed ore. It is a concrete structure footed on the ground, using no supporting columns. Tailing from the sink-float was used for aggregate. Cross conveyors for discharging ore are not required, nor is a tripper for filling. Segregation is minimized by drawing from different gates. An exhaust fan on top of the bin eliminates condensation due to temperature of the ore.21 A beam with an adjustable point of suspension near the center permits rigging rolls for removal in a very few minutes. This makes unnecessary the lacing of the cable through the hub bolts on one side, around the shaft on the other, and the trouble of balancing the load.8 The ratchet handle on a Symons crusher may be replaced by a drum with a cable wound on it. When the cable is pulled by a crane or hoist it causes the drum to revolve and thus screws or unscrews the bowl. This reduces handwork and materially shortens the time required for the job.3 To spread ore feed from an apron feeder over a belt conveyor, place a heavy steel bar about midway between the top

Jan 1, 1947

By Irving Lipkowitz

While the light metals are recognized generally as a distinct group in technical literature, economic classifications and data usually still treat them as part of the nonferrous group of metals. However, the economic characteristics of the light metals also differ markedly from those of other nonferrous metals. The distinctiveness of the light metals, as, a group and individually, becomes evident when their growth, since World War II is compared with that of other metals, as in Table 14.3.1. The growth of light-metals production has been much sharper than that of other metals. A weighted average for the light metals shows an increase of 112% during the 1958 to 1968 period. This compares with a 62% increase in the "All Primary Metals" component of the Federal Reserve Board Index of Industrial Production. The contrast was even sharper during the next six years (1968-1974), with light metals production up another 50% as against a 21 % increase in the FRB Primary Metals production index. The most important reason, however, for considering light metals separately is the trend and pace of technological change and not their distinctive statistics. Technology both creates and demands increasingly sophisticated materials. As technology advances and as all the world makes more extensive use of advanced technology, the importance of the light metals is likely to accelerate rapidly. There may be a profound clue to the future in the fact that light metals were predominant among the materials used in the construction of the Apollo 11 spacecraft. In determining what materials to use for the spacecraft and its equipment, the National Aeronautics and Space Administration (NASA) has explained that it did not look to "some of the more exotic metals" and relied instead on "generally proven materials." Accordingly, it apparently used a wide variety of metals, including precious metals, rare earths, special steels, copper, and light metals. What seems particularly significant is that, in seeking performance, NASA relied as heavily as it did on the light metals. Materials breakdown estimates show that aluminum accounted for over 75% of the materials used, titanium for another 5%, and magnesium was also used. Thus, light metals accounted for over 80%' of the materials used for the Apollo 11 spacecraft. The light metals are also unique in their availability. They rank high in abundance among the elements in the earth's crust. Aluminum is the third most abundant element, after oxygen and silicon, with magnesium ranking eighth, and titanium ninth. Among the structural metals, aluminum is the most abundant in the earth's crust, iron is second, magnesium third, and titanium fourth. This potential availability of light metals provides strong incentives for continuing improvements in process technology, because of two major national problems: (1) there is

Jan 1, 1976

By J. F. Myers, R. J. Tower

"There is nothing new under the sun." All over the world, mineral-dressing engineers are working at their problems, no two of which are alike. Each encounters equipment and process problems. Many devise simple ways and means of overcoming their difficulties. Many of these problems are quite common in the industry, yet, since no one human being seems capable of thinking of everything, these problems at some plants often are looked upon as necessary evils. The purpose of this symposium is to gather together, from competent engineers, devices and practices that have been useful to them. Most of the ideas contributed are not new, yet there is no plant operator, old timer or youngster, who will not find some idea herein that will give him a suggestion for improving his operation. Space does not permit a complete elaboration on all of the contributions offered. Each item is summarized, but this will be ample for those skilled in the art of mineral dressing. A list of contributors appears at the end of the paper, and the superior number at the end of each item identifies its source. General Equipment A signal light to show that a steel bin, containing relatively line, moist ore, is full, can be made by suspending a copper rod in the bin to a sufficient depth to ensure ample contact with the ore. One wire of a 32-volt circuit should be attached to the rod and one to the side of the bin. Sufficient current will flow to make the signal light burn. A 110-volt circuit could be used, but 32 volts ensures safety.10 Fig I shows a circular bin for crushed ore. It is a concrete structure footed on the ground, using no supporting columns. Tailing from the sink-float was used for aggregate. Cross conveyors for discharging ore are not required, nor is a tripper for filling. Segregation is minimized by drawing from different gates. An exhaust fan on top of the bin eliminates condensation due to temperature of the ore.21 A beam with an adjustable point of suspension near the center permits rigging rolls for removal in a very few minutes. This makes unnecessary the lacing of the cable through the hub bolts on one side, around the shaft on the other, and the trouble of balancing the load.8 The ratchet handle on a Symons crusher may be replaced by a drum with a cable wound on it. When the cable is pulled by a crane or hoist it causes the drum to revolve and thus screws or unscrews the bowl. This reduces handwork and materially shortens the time required for the job.' TO Spread ore feed from an apron feeder over a belt conveyor, place a heavy steel bar about midway between the top

Jan 1, 1949

By J Vann

The key functions of project evaluation are to assess potential profitability and to develop an effective operational design. For mining projects, design aspects include mining methodology, ore treatment methodology and production rates. All of these characteristics impact on project economics and overall value. Resource models, which form the ultimate basis of project evaluation, typically consist of tonnes above cut-off, grade above cut-off and the spatial distribution (connectivity) of tonnes/grade above cut-off, for one or more variables. Dilution, ore loss and metallurgical recovery are all modifying factors applied to the resource model during evaluation and determination of profitability. A key issue is: how is the value determined? In addition to traditional combination of in situ tonnes/grade, the following merit serious consideration: the concentration of deleterious elements, throughput rates, mining/processing costs and û importantly û metallurgical recovery. Geometallurgy is an emerging field targeted at integrating these issues by identifying either direct measures or proxies for throughput (hardness, grindability), recovery (liberation, mineral shape/texture, etc) and concentrate quality from easily collected macro-, meso- and microscopic data. These ægeometallurgical variablesÆ drive project costs and revenues in a fundamental way. For geometallurgical characterisation to have a real impact on business design, it must enable improved mine planning. When creating spatial estimates for such variables, it is preferable to find proxies that can be measured as close to the intact rock mass as possible. However, spatial estimation of proxies for geometallurgical properties and responses is complex and requires special consideration. Unlike grades, both proxies and absolute measures of geometallurgical variables are not necessarily linear or additive and therefore require very careful geostatistical consideration. In some cases, models must predict extreme values of geometallurgical attributes rather than averages. Incorrect characterisation of metallurgical recovery/throughput can (and has) led to misspecification of the scale of projects, and thus can be seriously value destructive. Aspects of geometallurgy have long been important in iron, bauxite, manganese and coal deposits and are increasingly on the radar for base and precious metal miners. However, as more metallurgically complex deposits are developed and mining of large-scale, low-grade deposits becomes more commonplace, the importance of characterising the metallurgical response in order to generate properly optimised projects will rapidly increase. It is possible that in many ætraditionalÆ (ie grades and tonnes) reserve models, the variables that drive the project are missing!

Jan 1, 2007

The key functions of project evaluation are to assess potential profitability and to develop an effective operational design. For mining projects, design aspects include mining methodology, ore treatment methodology and production rates. All of these characteristics impact on project economics and overall value. Resource models, which form the ultimate basis of project evaluation, typically consist of tonnes above cut-off, grade above cut-off and the spatial distribution (connectivity) of tonnes/grade above cut-off, for one or more variables. Dilution, ore loss and metallurgical recovery are all modifying factors applied to the resource model during evaluation and determination of profitability. A key issue is: how is the value determined? In addition to traditional combination of in situ tonnes/grade, the following merit serious consideration: the concentration of deleterious elements, throughput rates, mining/processing costs and - importantly - metallurgical recovery. Geometallurgy is an emerging field targeted at integrating these issues by identifying either direct measures or proxies for throughput (hardness, grindability), recovery (liberation, mineral shape/texture, etc) and concentrate quality from easily collected macro-, meso- and microscopic data. These 'geometallurgical variables' drive project costs and revenues in a fundamental way. For geometallurgical characterisation to have a real impact on business design, it must enable improved mine planning. When creating spatial estimates for such variables, it is preferable to find proxies that can be measured as close to the intact rock mass as possible. However, spatial estimation of proxies for geometallurgical properties and responses is complex and requires special consideration. Unlike grades, both proxies and absolute measures of geometallurgical variables are not necessarily linear or additive and therefore require very careful geostatistical consideration. In some cases, models must predict extreme values of geometallurgical attributes rather than averages. Incorrect characterisation of metallurgical recovery/throughput can (and has) led to misspecification of the scale of projects, and thus can be seriously value destructive. Aspects of geometallurgy have long been important in iron, bauxite, manganese and coal deposits and are increasingly on the radar for base and precious metal miners. However, as more metallurgically complex deposits are developed and mining of large-scale, low-grade deposits becomes more commonplace, the importance of characterising the metallurgical response in order to generate properly optimised projects will rapidly increase. It is possible that in many `traditional' (ie grades and tonnes) reserve models, the variables that drive the project are missing!

Jan 1, 2007

By H. P. Greenwald

IN the year just passed the Coal Division's Committee on Rock-Dusting reviewed the status of this safety measure in American coal mines and prepared a paper thereon which will be presented at the February meeting of the Institute. This paper supplements one appearing in Vol. 139 of the "Transactions," page 87 (1940). Because that paper will be issued soon, only a summary is given herein.

Jan 1, 1944

By Diler Katircioglu-Bayel

The effects of the operating parameters of media filling ratio, solid mass fraction, grinding media size and grinding time on the stirred media milling of talc were studied. The findings were assessed based on the product particle size (d50, d10), surface area (Sw) and energy consumption (Em). Furthermore, after determining the optimum grinding conditions, Box-Behnken statistical design was used to determine the effect of parameter interactions on the d50 size. The media filling ratio significantly affects d50 size decrease compared with solid mass fraction and grinding time. The minimum d50 size was also achieved under optimum grinding conditions.

By Glenn Davis

In the world of large scale open pit mining, the majority of a mines operating cost is tied to the removal and transportation of the overburden waste material. Typically, many large haul trucks are employed to transport this overburden from each excavating face. The trucks transfer the waste material from deep within the pit to waste dumps on the surface incurring significant costs in operators, road construction and maintenance, vehicle maintenance staff and support facilities, fuel, tires, and spare parts, as well as the capital cost of the truck fleet itself. In addition, the haulage of the actual mined material carries similar operational costs. In both cases, these costs grow as the mine face advances and pit haulage distances increase. Reducing truck haulage is one key to the success of the Dual Truck Mobile Sizer (DTMS). Being the world?s first fully mobile truck dump station, transportation costs can be significantly reduced as the mine face advances. Furthermore, when used in conjunction with a shiftable face conveyor and a mobile overland hopper, substantial cost savings can be achieved. The mobility of the system allows for the considerable reduction in the haul truck fleet. Overall mine site emissions levels are greatly reduced by the fleet elimination, as well as keeping the majority of the hauls on a flat grade within the pit. Emission levels on a typical truck will dramatically spike as the angle and the length of the haul are increased. Moreover, comparing diesel engines versus electric powered conveyors to move the material contributes to the realized savings.

May 1, 2010

By Gregory A. Knapp

Treatment of industrial wastewaters generally advances with specific chemical concentration and mass-flow targets, established by National Pollutant Discharge Elimination System (NPDES) permits. Treated discharges must also address toxicity to test and receiving water organisms. Various parameters might need consideration during treatment design and planning, such as the known toxicants, hardness, alkalinity, solids, nutrients, metals in both the dissolved and particulate state, and even flow. Since toxicity is used as a "catch all" regulatory monitoring tool, design of treatment systems should focus on the various factors contributing to toxicity.

Jan 1, 1996

By A S. Kurilko

For mines located in the cryolitic zone, thermal conditions are an important factor for all kinds of mining works, especially for ventilation of workings. In the present paper, some models of mine air heat transfer considering air distribution in a net of mine workings are developed. A combined solution is suggested for heat transfer and air distribution problems in mine workings and other underground structures located in the cryolitic zone. A software package is also presented for calculating temperature conditions in an underground refrigeration plant and for optimisation of ventilation conditions. This software uses a special 3D mathematical model to describe heat transfer in a freezing chamber between surrounding rock massif and stored product as well as between atmospheric air and the daylight surface of rock massif. A problem requiring strengthening of a backfill material and its thermal interaction with surrounding rocks during underground deposit mining by horizontal layers in conditions of the cryolitic zone is also discussed. The developed program takes into account cement consumption, geometrical dimensions of workings filled and a sequence of deposit mining.

Jan 1, 2005

By R. L. Keaton

Since the earliest days of mining, the job of digging coal out of the earth has been considered one of the world?s most dangerous occupations. From 1880 to 1910, mine explosions and other accidents claimed thousands of victims. In 1907 alone, over three thousand deaths occurred in U.S. coal mines. Public concern has prompted the passage of much needed safety legislation; from the creation of the U.S. Bureau of Mines in 1910, to the comprehensive laws of the Federal Mine Safety and Health Act of 1977. This type of legislation, along with the cooperation of industry, labor, and MSHA has contributed greatly in making mining safer and more healthful. Mining deaths and injuries have declined Significantly since those early days. However, even though this trend is positive, none of US can afford to look at the injury numbers and frequency rates and label them as acceptable.

Jan 1, 1988

By R. R. Hornor

Due mainly to conditions brought about by the war , the metal mining industry in this country is now passing through one of the most critical stages in its history , and is confronted by new problems upon the solution and adjustment of which depends , in a large measure , its future welfare and prosperity . The chief factors contributing to the cost of production are the cost of labor and supplies . It is conceded by our leading mine operators , managers , and engineers that any material reduction in the cost of labor or supplies , within possibly the next two or three years , cannot be anticipated , anl it is not thought likely that pre - war prices will ever again prevail . This being true , the mine operator must look in some cther direction to effect economies that will lower production costs . If this cannot be accomplished it will mean , in many instances , that mines and metallurgical works will have to be closed and abandoned , which will tend to disorganize the entire industry . How to lower production costs and still maintain the present high standard of wage , is the problem that is engaging the serious attention of mine operators and managers over the entire country . In As a solution to this problem it is thought that the most promising field of investigation lies in the direction of systematizing and standardizing mining practice , so as to effect economies in the use of both labor and materials . other words , to eliminate , in so far as possible , unproductive effort and waste and thereby secure a maximum of productive results , It is not the idea to speed up work or to demand a greater effort on the part of the workman , but rather so to systematize and standardize the various under ground operations that his energy will be directed into more useful and productive channels ,

Dec 1, 1919

By O. D. Gaither

This paper is an analytical study of the flow of fluids through small vertical conduits. Small conduits are defined as 11/4-in. nominal diameter tubing size and smaller, and approximately twice this area for annular conduits (i.e., 1- X 21/2-in. annulus and smaller). Experimental data are presented for the 1-X2-in. and 11/4- X 2%-in. annuli, and the I-in. and 11/4-in. tubing, since these represent the small conduit sizes and configurations generally encountered in oilfield applications. Data have been gathered for these conduits for single-phase water, single-phase gas and two-phase water-gas mixtures, with particular emphasis on high gas-liquid ratios. Water rates in excess of 2,000 BID and gas rates in excess of 2.5 MMcf/D, and two-phase flow ratios in between these two, represent the scope of the data gathered. Existing equations have been applied to predict flowing pressures and compared with experimental data. New correlations have been developed. INTRODUCTION The increased economic pressure on the domestic oil industry in the United States has constantly required the use of new techniques and equipment designed to reduce the cost of finding and producing oil and gas. Since tangible items are most readily apparent in economic analysis, the advent of lower-cost well completions was inevitable. One of the methods used to reduce costs which has received widespread attention is the slim-hole completion technique where tubing is used as the well casing and in which small conduits are used for tubing if necessary. Small conduits, defined by Kirkpatrick1 as "11/4-in. diameter nominal tubing and smaller for tubing flow and less than twice the 11/4-in. diameter nominal tubing internal flow area for annulus flow", have also found widespread usage as siphon strings for de-watering gas wells and as "kill" strings in deep high-pressure oil and gas wells. The growing use of small-diameter tubing has resulted in an increased need for development of improved methods to measure or predict flowing bottom-hole pressures since the physical dimensions generally preclude the use of subsurface-recording pressure gauges. Even in the cases where small bombs are available, the relatively high velocities encountered at nominal flow rates make it necessary to use excessive weight bars or special hold-down devices. Attempts to use recognized correlations to accurately predict flowing or gas-lift performance in wells equipped with small conduits have been generally unsuccessful. Insufficient field data were available to allow the development of a correlation on this basis, and an experimental approach was applied in an attempt to obtain a workable relation. The experimental approach used to obtain the data presented in this paper was actually a compromise between a field installation and a laboratory study. A test well 1,000 ft in length was used to obtain flow data on single-phase liquid, single-phase gas and two-phase water-gas flowing mixtures. Liquid rates up to 2,200 B/D and gas rates up to 3 MMcf/D were used in the single-phase flow studies. Two-phase flow rates from 100 to 600 B/D with gas-liquid ratios from 500 to 8,000 cu ft/bbl were recorded. Experimental data were obtained for single- and two-phase flow through 1-in and 11/4-in. nominal tubing, and through the annuli between 1- and 2-in. and 11/4- and 2%-in. nominal tubing strings. Experimental results for the two-phase flow are compared to the Poettmann-Carpenter correlation2 which is widely used as a comparative standard for development of multiphase flow predictions in flowing and gas-lift wells. Correlations developed by Tek,3 Baxendell and Thomas" were also investigated. The experimental data recorded herein fell in between the two flow regimes as defined by Ros," and this correlation also failed to yield satisfactory results. The fact that existing correlations failed to confirm the experimental data led to the need for development of a new correlation. Although a two-phase flow study was the primary objective of this investigation, data were also recorded for single-phase flow of water and gas, and constants were developed relating to pipe roughness and equivalent diameters for annular flow. These single-phase studies assisted materially in the development of certain of the two-phase flow results. Considerable previous work has been published which presented relationship of surface measurements to bottom-hole condition. The works of Buthod and Whiteley,6 Jones,' Poettmannb and the Texas Railroad Commission" are classic examples of the successful use of mathematical relationships which allow acceptable predictions of subsurface pressures, when gas is the flowing fluid. Darcy and others have derived relationships which may be used with minor modifications to predict subsurface flowing conditions in injection and water-supply wells. As previously stated, the application of the single-phase flow relationships

By H. L. Overton, J. B. Lipson

The concept of sodium single-ion equivalent activity as developed by Gondouin, Tixier and Simard,' was used to determine the filtrate resistivity-activity relationships for 150 laboratory and 49 field drilling muds. With the exception of the native and phosphate high-resistivity muds and the calcium-treated muds, the filtrate resistivity-activity relationships were found to be within 20 per cent of that for pure sodium-chloride solutions. Gondouin, et al,* previously suggested a method of treating the high-resistivity muds in quantitative electrical log analysis. A new treatment is presented which uses the P-alkalinity of the filtrate as a correlating parameter in handling the calcium-treated muds in quantitative electrical log analysis. INTRODUCTION Gondouin, Tixier, and Simard in 1957 introduced new interpretive procedures for analyzing the self-potential curve of electric logging. They re-emphasized the previous work of the Schlumberger brothers, Wyllie and others, and re-defined the activity concept in terms of a number which they termed the effective resistivity. Their procedures are particuarly effective when the connate-water resistivities are less than 0.08 ohm-m or greater than 0.3 ohm-m. For gyp muds where the calcium content is known, a procedure was presented which allows calculation of the connate-water resistivity with improved accuracy. These procedures assume that one of the fluids in the system is a pure sodium-chloride solution, but they are not limited by the assumptions. For the fresh and saline connate waters, for instance, it is assumed that the drilling mud filtrate is a pure sodium-chloride solution. For the gyp mud interpretive procedure, it is assumed that the connate water is a pure sodium-chloride solution. Brown,' on the other hand, has suggested that it would be extremely fortuitous if drilling mud filtrates could all be treated electrochemically as sodium-chloride solutions, and he cites some examples where discrepancies exist. A study has been made of the deviations of sodium single-ion equivalent activities, an of drilling mud filtrates from that of pure sodium-chloride solutions. Drilling fluids in common use on the Texas and Louisiana Gulf Coast and laboratory-controlled muds were investigated. Using a cell patterned after Gondouin, et al, (Fig. I), the equivalent activities were measured. It should be remembered here that the activity measured is merely an index which uses numbers that represent the sodium single-ion equivalent activity a,., of the mud filtrate. The membrane potential developed across the cell was determined with a null-type potentiometer. The resistivities of the solutions were measured by the four-electrode method. The resistivity system was calibrated by using saturated KC1 solution as a standard. Chemical properties of the drilling fluids studied were measured with standard API-approved equipment for the particular property in question. For the activity measurements, two shale discs were chosen to serve as cationic membranes. These two discs were both 1 1/4 in. in diameter and, respectively, 1/4 and 1/8 in. in thickness. The membrane potential, Em, was determined using the shale discs as cationic selective membranes separating two standard sodium-chloride solutions of known mean activity. Then by comparing the constant Km in the following equation, with the theoretical value of — 59 mv at 75OF, the perfection of the membrane was determined. The variation of Km for the two membranes used in this experimental work, as well as one of the many unsuitable membranes, is shown in Fig. 2. The measurement of the activity of mud filtrate involves the balancing of its combined individual activities against a standard solution of known mean activity. At the point where there exists zero potential across the membrane cell, the activity effects may be assumed equal for all practical purposes. The mechanics of making a null reading of this sort requires having a large number of different mean activity solutions. A more practical method involves