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By John Dean Smith

In order to discuss problem solving techniques for the future. we must first review the past. This paper will discuss the drilling and blasting problems and techniques that were used by .Imax Coal in the past few years, tn those of today.

Jan 1, 1991

By Mattos J. L. C

Drilling and blasting with explosives in mining operations near communities require careful planning to mitigate socio-environmental impacts. Ground vibration, noise emission, flyrock, and dust dispersion are factors that may trigger conflicts with local populations. However, large-scale operations demand high productivity and intense material handling, making it essential to balance operational performance with impact control. The adoption of best practices, combined with advanced monitoring and mitigation technologies, enables sustainable mining even in proximity to inhabited areas. This study proposes the use of double and triple-deck blasting techniques with large-diameter boreholes (12 ¼” – 311 mm), addressing the sizing of charges and decks, as well as measures aimed at reducing noise perceived by nearby communities. The approach seeks to maintain the use of large drilling rigs already present in the operation, avoiding costs related to premature equipment replacement or expensive alternatives, while minimizing environmental and social impacts and promoting a more balanced and responsible mining model.

Jan 26, 2026

By Joel Moskowitz

In 1990, the United States General Services Administration (GSA) issued a contract for design and construction of a new federal court building in New York City. Mueser Rutledge Consulting Engineers (MRCE) served as Project Geotechnical Engineers. The project site is in the historic government district at Foley Square. It is surrounded by the New York County Courthouse to the west, an existing federal prison building and federal courthouse across Pearl Street to the south and southwest, an office structure to the north, and a residential tower to the east. The interior of the site was crossed by streets which have now been demapped. As with many urban sites, this site was previously occupied by tenement buildings or industrial structures demolished near the turn of the century. Remains of old building foundations were exposed during construction excavation. In addition, buried fuel oil tanks servicing the adjacent courthouse were removed and the usual assortment of urban utilities had to be relocated for the new building foundations. Ground surface elevations vary from about 4.5 to 6 m above the local Mean High Water Datum Plane.

Jan 1, 1996

By B. E. Morgan, C. K. Dumbauld

The need for a low-strength cementing composition for use in well cementing is reviewed and results are presented of laboratory and experimental field tests of a modified cement having a controlled ultimate tensile strength of approximately 200 psi. The modified cementing composition may he prepared from either high early strength or normal portland cements by the addition of bentonite clay and a suitable agent for dispersing and controlling the set of the slurry. Substitution of the modified cement for conventional slow-set cements may give better completion results in many wells because the modified cementing composition has lower set strength, lower slurry density, and greater slurry stability than conventional cement slurrieh. The lower ultimate strength allows greater penetration with less shattering of the set cement when perforating casing and cement. The lower elurry density allows the placement of longer columns of cement slurry, and the greater slurry stability reduces the possibility of having an uncemented section caused by the settling of cement particles before the cement set.. INTRODUCTION High strength lias always been one of the accepted criteria of a good cement. During the early use of portland cement in well cementing. emphasis was placed upon securing cements with higher strengths. In 1931, Barkis' reported that, "Normal oil well cements have been improved to develop greater strengths and uniformity of product, which has aided in producing successful jobs in cementing the deeper strings." As long as most wells were completed by the open-hole method. the use of cements having high strengths seemed desirable, and there was no objection raised against high-strength cementing compositions. For a number of years. how-ever, the industry has been completing a large numher of wells by setting and cementing casing through productive horizons and then obtaining production by gun-perforating the section of casing opposite the desired interval. Although this method has been generally successful, difficulties have been experienced in some cases in completing or recompleting wells because of apparent lack of adequate penetration by the bullets through the casing and surrounding sheath of cement and into producing formation. In addition to the penetration trouble: there have been indications that fracturing and shattering of the set cement by perforating might he a contributing factor in causing the failure of some jobs to exclude water or gas from oil producing zones. The possibility that cements having high set strengths were contributing to til difficully ill obtaining satihfartory perforating results has re. ceived attention during recent years. Gun perforating tests conducted in 1944 showed that the depth of bullet penetration into set cement varied with the hardness of the cement, the greater the strength of the cement the less being the penetration. In 1946, Farris2 pointed out that high strength cements were not needed in well cementing, and in 1947, data published by Oliphant and Farris3 showed that set cement was perforated without shattering at approximately 150 psi tensile strength. whereas at approximately 300 psi tensile strength severe cracking and shattering occurred. Oliphant and Farris suggested that wells be perforated at the proper time interval after placement of the cement so that the set cement would have the desired strength. Several difficulties may he encountered in trying to perforate a cement job at the correct time to catch the tensile strength near 150 psi. The rate of strength development of different cements varies considerably. This fact is illustrated by results of tensile strength measurements presented in Fig. 1. These data show that at 175°F the tensile strengths of three conventional slow-set cements varied from 75 to 235 psi at the end of 12 hours. After 24 hours, the tensile strengths varied from 200 to 455 psi. The rate of strength development is affected. also. by the temperature of the forniation, and this adds to the uncertainty of perforating at the rorrect time, since accurate well cementing temperatures may not he known in many cases. Furthermore, in the recomple-tion of wells it is sometimes necessary to perforate cement which has set for a long period and has developed maximum or final strength. In view of the apparent need for a cementing composition having a controlled ultimate strength, an investigation was

Jan 1, 1951

By C. K. Dumbauld, B. E. Morgan

The need for a low-strength cementing composition for use in well cementing is reviewed and results are presented of laboratory and experimental field tests of a modified cement having a controlled ultimate tensile strength of approximately 200 psi. The modified cementing composition may he prepared from either high early strength or normal portland cements by the addition of bentonite clay and a suitable agent for dispersing and controlling the set of the slurry. Substitution of the modified cement for conventional slow-set cements may give better completion results in many wells because the modified cementing composition has lower set strength, lower slurry density, and greater slurry stability than conventional cement slurrieh. The lower ultimate strength allows greater penetration with less shattering of the set cement when perforating casing and cement. The lower elurry density allows the placement of longer columns of cement slurry, and the greater slurry stability reduces the possibility of having an uncemented section caused by the settling of cement particles before the cement set.. INTRODUCTION High strength lias always been one of the accepted criteria of a good cement. During the early use of portland cement in well cementing. emphasis was placed upon securing cements with higher strengths. In 1931, Barkis' reported that, "Normal oil well cements have been improved to develop greater strengths and uniformity of product, which has aided in producing successful jobs in cementing the deeper strings." As long as most wells were completed by the open-hole method. the use of cements having high strengths seemed desirable, and there was no objection raised against high-strength cementing compositions. For a number of years. how-ever, the industry has been completing a large numher of wells by setting and cementing casing through productive horizons and then obtaining production by gun-perforating the section of casing opposite the desired interval. Although this method has been generally successful, difficulties have been experienced in some cases in completing or recompleting wells because of apparent lack of adequate penetration by the bullets through the casing and surrounding sheath of cement and into producing formation. In addition to the penetration trouble: there have been indications that fracturing and shattering of the set cement by perforating might he a contributing factor in causing the failure of some jobs to exclude water or gas from oil producing zones. The possibility that cements having high set strengths were contributing to til difficully ill obtaining satihfartory perforating results has re. ceived attention during recent years. Gun perforating tests conducted in 1944 showed that the depth of bullet penetration into set cement varied with the hardness of the cement, the greater the strength of the cement the less being the penetration. In 1946, Farris2 pointed out that high strength cements were not needed in well cementing, and in 1947, data published by Oliphant and Farris3 showed that set cement was perforated without shattering at approximately 150 psi tensile strength. whereas at approximately 300 psi tensile strength severe cracking and shattering occurred. Oliphant and Farris suggested that wells be perforated at the proper time interval after placement of the cement so that the set cement would have the desired strength. Several difficulties may he encountered in trying to perforate a cement job at the correct time to catch the tensile strength near 150 psi. The rate of strength development of different cements varies considerably. This fact is illustrated by results of tensile strength measurements presented in Fig. 1. These data show that at 175°F the tensile strengths of three conventional slow-set cements varied from 75 to 235 psi at the end of 12 hours. After 24 hours, the tensile strengths varied from 200 to 455 psi. The rate of strength development is affected. also. by the temperature of the forniation, and this adds to the uncertainty of perforating at the rorrect time, since accurate well cementing temperatures may not he known in many cases. Furthermore, in the recomple-tion of wells it is sometimes necessary to perforate cement which has set for a long period and has developed maximum or final strength. In view of the apparent need for a cementing composition having a controlled ultimate strength, an investigation was

Jan 1, 1951

By W. B. Lilienthal, J. C. Melrose

The application of Bingham's law to the behavior of drilling fluids in a rotational viscometer permits the expression of viscometric data in terms of plastic viscosity and yield value, the flow properties of a plastic fluid. A commercially available rotational viscometer is described, and when modified to a multispeed type viscometer, is shown to provide a simple and convenient instrument for the measurement of these properties both in the laboratory and in the field. The data obtained are shown to be useful in defining and understanding mud control problems relating to chemical treatment and to the hydro-dynamic behavior of muds. INTRODUCTION The highly complex drilling fluids which are required for deep drilling often give rise to new and unusual mud control problems. Rapid and economic solutions to these problems may require, on the one hand, better understanding of the changes which contaminants and chemical treating agents produce in the colloidal and inert solids of the mud, or, on the other hand, closer control of the hydrodynamic behavior of the mud. The latter objective obviously can be achieved only if a correct rheological analysis of the flow behavior of drilling muds is available and if this is accompanied by the appropriate rheological measurements. The purpose of this paper is to describe such measurements in the field, and to show how the resulting data can be of value in solving difficult mud control problems. It is now generally recognized that Bingham's law of plastic flow can be utilized in describing the hydrodynamic behavior of drilling fluids in the non-turbulent flow range. Beck, Nuss, and Dunn' have recently applied this law to the flow of mud in small pipes, and Rogers2 has reviewed the rather extensive literature on this subject. So far, however, the use of Bingham's law has been restricted to the analysis of mud flow in pipes or capillary tubes, and it has not been directly applied to the flow in rotational viscometers. In the work to be reprted, the Reiner-Riwlin3 equation for the flow of a plastic fluid in a rotational viscometer has been utilized to permit the expression of multispeed viscometric data in terms of plastic viscosity and yield value. the two absolute flow properties of a plastic fluid. With regard to the application of these measurements, the calculation of the relationship between pumping rate and pressure drop, both in the drill pipe and annular space, has long been a subject of interest. Beck, Nuss, and Dunn,' following Caldwell and Babbitt: base their calculations for non-turbulent flow on Buckingham's integration of Bingham's law for pipe flow and measurements of the plastic viscosity (rigidity in their terminology) and yield value. In the case of turbulent flow, Fanning's equation is employed, and the pressure drop is relatively insensitive to the flow properties of the mud. Since flow in the drill pipe is likely to be turbulent at usual circulation rates, the plastic flow properties will chiefly influence the pressure drop in the annular space. As pointed out by Beck,' the control of this component of the total pressure drop may be of special importance where lost circulation problems are encountered. Other hydrodynamic problems to which it should be possible to apply measurements of the plastic flow properties include predictions of the velocity distribution in non-turbulent flow and the critical velocity for transition to turbulence. Plastic viscosity and yield value. as abmlute flow propertie.;, will reflect the colloidal or surface-active behavior of the solids present in drilling fluids. Measurements of these properties should therefore find application in developing a better understanding of such behavior and in characterizing the type and condition of these solids. Garrison and ten Brink have utilized multispeed viscometric data in this manner. although their measurements were not expressed in terms of the absolute flow properties. In connection with the application of these measurements, it should be recognized that the presently used one-point viscosity measurements are relative in nature. The API Stormer 600-rpm measurement, for example. is a function of both plastic viscosity and yield value, as well as mud weight, and will often be misleading when its application to mud control problems is attempted. NOMENCLATURE, UNITS, AND DEFINITIONS In Fig. 1 an idealized plot is given of the flow variables involved in any viscometric measurement. It is seen that the flow behavior of plastic fluids is characterized by two constants — plastic viscosity, µp, and yield value, F. Other workers hate used the term rigidity for plastic viscosity or the term mobility for its reciprocal. The term plastic viscosity, however, emphasizes the close relation this property bears to the viscosity of a true fluid and is expressed in the familiar viscosity units of centipoises. The yield value is expressed in lbs/100 sq ft, the units adopted for gel strength measurements with the APT shearometer. Definitions of these properties based on rheological or macrc)scopic flow considerations follow from Fig. 1. The plastic viscosity of a substance obeying Bingham's equation is defined

Jan 1, 1951

By J. C. Melrose, W. B. Lilienthal

The application of Bingham's law to the behavior of drilling fluids in a rotational viscometer permits the expression of viscometric data in terms of plastic viscosity and yield value, the flow properties of a plastic fluid. A commercially available rotational viscometer is described, and when modified to a multispeed type viscometer, is shown to provide a simple and convenient instrument for the measurement of these properties both in the laboratory and in the field. The data obtained are shown to be useful in defining and understanding mud control problems relating to chemical treatment and to the hydro-dynamic behavior of muds. INTRODUCTION The highly complex drilling fluids which are required for deep drilling often give rise to new and unusual mud control problems. Rapid and economic solutions to these problems may require, on the one hand, better understanding of the changes which contaminants and chemical treating agents produce in the colloidal and inert solids of the mud, or, on the other hand, closer control of the hydrodynamic behavior of the mud. The latter objective obviously can be achieved only if a correct rheological analysis of the flow behavior of drilling muds is available and if this is accompanied by the appropriate rheological measurements. The purpose of this paper is to describe such measurements in the field, and to show how the resulting data can be of value in solving difficult mud control problems. It is now generally recognized that Bingham's law of plastic flow can be utilized in describing the hydrodynamic behavior of drilling fluids in the non-turbulent flow range. Beck, Nuss, and Dunn' have recently applied this law to the flow of mud in small pipes, and Rogers2 has reviewed the rather extensive literature on this subject. So far, however, the use of Bingham's law has been restricted to the analysis of mud flow in pipes or capillary tubes, and it has not been directly applied to the flow in rotational viscometers. In the work to be reprted, the Reiner-Riwlin3 equation for the flow of a plastic fluid in a rotational viscometer has been utilized to permit the expression of multispeed viscometric data in terms of plastic viscosity and yield value. the two absolute flow properties of a plastic fluid. With regard to the application of these measurements, the calculation of the relationship between pumping rate and pressure drop, both in the drill pipe and annular space, has long been a subject of interest. Beck, Nuss, and Dunn,' following Caldwell and Babbitt: base their calculations for non-turbulent flow on Buckingham's integration of Bingham's law for pipe flow and measurements of the plastic viscosity (rigidity in their terminology) and yield value. In the case of turbulent flow, Fanning's equation is employed, and the pressure drop is relatively insensitive to the flow properties of the mud. Since flow in the drill pipe is likely to be turbulent at usual circulation rates, the plastic flow properties will chiefly influence the pressure drop in the annular space. As pointed out by Beck,' the control of this component of the total pressure drop may be of special importance where lost circulation problems are encountered. Other hydrodynamic problems to which it should be possible to apply measurements of the plastic flow properties include predictions of the velocity distribution in non-turbulent flow and the critical velocity for transition to turbulence. Plastic viscosity and yield value. as abmlute flow propertie.;, will reflect the colloidal or surface-active behavior of the solids present in drilling fluids. Measurements of these properties should therefore find application in developing a better understanding of such behavior and in characterizing the type and condition of these solids. Garrison and ten Brink have utilized multispeed viscometric data in this manner. although their measurements were not expressed in terms of the absolute flow properties. In connection with the application of these measurements, it should be recognized that the presently used one-point viscosity measurements are relative in nature. The API Stormer 600-rpm measurement, for example. is a function of both plastic viscosity and yield value, as well as mud weight, and will often be misleading when its application to mud control problems is attempted. NOMENCLATURE, UNITS, AND DEFINITIONS In Fig. 1 an idealized plot is given of the flow variables involved in any viscometric measurement. It is seen that the flow behavior of plastic fluids is characterized by two constants — plastic viscosity, µp, and yield value, F. Other workers hate used the term rigidity for plastic viscosity or the term mobility for its reciprocal. The term plastic viscosity, however, emphasizes the close relation this property bears to the viscosity of a true fluid and is expressed in the familiar viscosity units of centipoises. The yield value is expressed in lbs/100 sq ft, the units adopted for gel strength measurements with the APT shearometer. Definitions of these properties based on rheological or macrc)scopic flow considerations follow from Fig. 1. The plastic viscosity of a substance obeying Bingham's equation is defined

Jan 1, 1951

By Ronald E. Walkington

The U.S. Department of Energy (DOE) is building the world's newest accelerator-based, pulsed-neutron system, called Spallation Neutron Source (SNS). The facility, located in Oak Ridge, Tennessee, is a partnership of six DOE national laboratories - Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. Oak Ridge has the responsibility for managing the partnership and ultimately operating SNS. SNS will provide opportunities for up to 2,000 researchers each year from universities, national laboratories and industry from around the world for basic and applied research and technology development in the fields of materials science, magnetic materials, polymers and complex fluids, chemistry and biology. When completed, this state-of-the-art research facility will provide neutron beams that are 12 times more intense than any other such source in the world. Most of the world's neutron sources were built decades ago. Therefore, it is easy to understand how SNS will provide new research opportunities unavailable elsewhere, and at the same time restore United States leadership in neutron sciences. Neutron scattering research provides valuable information about materials that cannot be obtained through microscopy, X-rays, spectroscopes, or other techniques. The information gained from neutron scattering research leads to improved materials that are used in high-temperature superconductors, powerful lightweight magnets, aluminum bridge decks, jet aircraft, compact and computer discs, magnetic recording tapes, shatter-proof windshields, and many other applications. SNS is like a flashing strobe light providing high-speed illumination of an object and will record the structure of physical and biological materials from plastics to proteins. Because neutrons have no charge, they can penetrate more deeply into materials than do X-rays, light, or electrons and thus reveal bulk structure and properties of materials. SNS will help to understand and "engineer" better materials and the manufacture of better products at the atomic level. Our high-technology society demands new materials that are stronger, lighter, and cheaper yet perform well under severe conditions. SNS, which is designed with the future in mind, will be the leading neutron research facility for many years to come.

Jan 1, 2001

By Raffaella Granata, Daniele Vanni

"This paper presents the drilling and grouting program performed at two abandoned landfills located into former calcarenite rock quarries in Manfredonia, Italy. Tests performed after the abandonment of the landfills detected leachate infiltration into the groundwater, which required the implementation of a remedial program. In order to seal the rock fissures and create an impervious basin at the base of the two landfills, sub-horizontal boreholes were drilled and grouted into the rock under the waste deposits. At the same time, sub-vertical boreholes were drilled and grouted along the perimeter, to laterally confine the landfills. Finally, the landfills were properly capped with an HDPE membrane, geogrid, geotextile and topsoil. The methodology implemented to create a watertight barrier under the two landfills was innovative and cost-effective. Moreover, the drilling and grouting minimized the environmental impact of the remedial work, since the waste remained in their original location and were not affected by the remedial process.IntroductionThe two landfills, “Pariti-1 RSU” and “Conte di Troia”, are located approximately 6 km (4 miles) southwest of Manfredonia, a small town close to Foggia, Italy (Fig. 1). These landfills are located into two rock quarries, formerly used for the extraction of calcarenite (i.e., a weak calcareous sandstone, in tuff facies), and were abandoned in the early 90s. The two landfills cover a total area of about 45,000 m2 (11.2 acres), and mainly include urban solid waste with a depth of up to 25 m (82 ft). The main characteristics of the two waste landfills are listed in Table 1."

Jan 1, 2016

By B. J. Dave, Ashok J. Desai, Allen J. Hulshizer

This paper presents various design and construction considerations involved in developing an underwater installation of lined, large diameter shafts not known to have been previously accomplished for the diameter size, depth or ground conditions identified with the Seabrook Power Station. Outlined approach provides for driving tunnels independent of shaft sinking operation, permits the use of prefabricated shaft lining and incorporates a safe dry tap method for connecting the shafts to the tunnels. INTRODUCTION The Seabrook Power Station, located two miles inland from the Atlantic Ocean, at Seabrook, New Hampshire, is a two unit, nuclear powered, electric generating plant, each unit having a capacity of 1150 megawatts (electric). Typical to all steam driven generators is the requirement for large quantities of water. Requirements for the Seabrook Plant will be met by intaking and discharging approximately 850,000 gpm of ocean water at a considerable distance from the shore line in water depths that render the environmental impact inconsequential. Obtaining, conveying and discharging such large quantities of water represents a major undertaking, particularly under today's environmental controls. Tunnels are well suited to reducing the environmental impact at the Seabrook site by conveying the water about 250 feet deep under the salt marsh (a valuable ecological feature) and under the beach well out into the ocean without any noticeable ground surface disturbance. An alternate approach utilizing trenched piping would have created some disturbances and was environmentally less desirable. The tunnels connect to intake and discharge

Jan 1, 1976

By G. H. Tausch, T. A. Huber

Very encouraging progress has been made ill the develop-ment of the permanent-type well completion which decreases considerable the cost of completions and workovers and aid-in the acquisition of reliable reservoir information at low cost. Completion and remedial operations are performed with tool,; which pass through the well tubing. Perforating and plug-hack operations can be done with the tubing in place and do not require pipe-handling equipment. Because of the many advantages afforded by this method, development work is going forward in anticipation of ultimately being able 10 use it to perform all usual well completion and workover operations. Effort is also being directed to the development of a more permanent type of lift equipment suitable for use with the permanent-type well completion. INTRODUCTION The permanent-type well completion in one in which the tubing and well-head are set in place only once in the life of the well and the completion or remedial work is performed through the tubing with a tubing-type perforator. a retrievable tubing extension. and other wire-line tools. This new type completion has made possible the saving of one to two days' rig time in the completion of each of several hundred wells During the last two years, and use of equipment developed for this type of completion has resulted in a 75 per cent reduction in cost. of certain types of workovers. In addition. the more reliable indication of the commercial value of a reservoir and the more accurate general reservoir information made Possible promise to be of even greater value in oil recovery than the reduction of costs for completions and workovers Recently. several well.. were worked over by using the retrievable tubing extension suspended on a swab line to plug back with cement and then perforating a higher producing interval with the tubing-type perforator, thus opening the way for complete through-the-tubing workovers which may be performed without pipe-handling equipment or mud. Those items attendant to the use of pipe-handling equipment and mud. such as hoard matting rig substructure. and pits. were also eliminated. There are indications that the elimination of drilling mud during completion and workover operations will frequently give increased well productivity, as plugging of the perforation. will not occur. It ii now possible to perforate selectively small sections of the producing interval and to test a well through these sections prior to perforating more interval. The perforating of additional interval will not entail the costly operations of killing the well and pulling tubing, nor will the old or the new perforations be plugged. The productivity of .mall sections of a reservoir and the actual gas-oil or oil-water contacts may now be determined economically under flowing condition.. Selective completions can be made in this manner to delay gas and water problems and bring about maximum oil recovery. At the present time, gas lift appears to offer the greatest potentialities for artificial lift in the permanent-type well com"letion since it can provide full-open tubing to accommodate the through-the-tubing tools and it may be ultimately developed into a fairly permanent type of lift. With precent-day pas-lift equipment. valve or mandrel failure necessitates occacio11al removal of the tubing. thereby reducing to some extent the permanence of the completion. New gas-lift valves are now

Jan 1, 1953

By E. D. McMurry

INTRODUCTION Before discussing the use of the free piston; it may be well to explain briefly the type of gas lift valves with which the loo] is designed to function. The gas lift valve ii nothing more or less than a small back pressure regulator. It; construction consists of an outer hous ing covering a seamless metallic bellows in such a way as in form a sealed pressure vessel or pressure dome. To the bellow* in attached a stem and to this stem is attached a .rating member. When the valve is run into the hole, a pre-delermined pressure charge is placed in the pressure dome. As shown in Fig. 1. the valve is furnished in four different major assem-blies. to accomplish good results in different types of wells. The valve is mounted on a pup joint (Fig. 2a) : the eoin-plele assembly is entered into the tubing siring at the desired location. Each valve is furnished with a revere flow check valve (Fig. 2-b) to eliminate any back wash through the mechanism. Valve action is as follows: At any time the casing pressure is allowed to exceed the pressure forces within the pressure dome of the valve, the valve simply opens and passes gas from the rasing annulus into the tubing. When the casing pressure forces arc allowed to bleed to a force less than the pressure force within the dome, of the valve. the valve closes. With this type of construction. it is possible to open and close the valve or valves at will from the surface, the medium of the gas pressure in the rasing annnlus. The cycle of operation is governed by a tine cycle motor valve, commonly referred to as a gas lift interutitter or gas life surfacr controller (Fig. 3). In actual practice. after the well is unloaded only one valve is in operation . . . all other valve.: remain in the closed position. On pre-determined time cycles, it is possible to open and close this operating valve at will, and to pass the desired amount of gas through this valve wheneler needed. This method of gas lift is widelv used and has been found In be very efficient. However, it has long been known that even greater efficiency would be obtained if it were possible to place Piston between the injected gas and the fluid head. The free piston which will be discussed here was designed to accomplish this end and has been found to do so with very satisfactory results. DESIGN AND OPERATION OF THE FREE PISTON Basically. the free piston consist- of a telescoping assembly in which are incorporated the various control and operating parts (Fig. A set of sleeve valves which are opened and closed by movement of the telescoping section is contained in the. tool. A cross section of the free piston is shown in Fig. 4-11, 'rile main body cotain- a seamless monel bellows of the same type as that generally used in pressure charged gas lift valves (Fig. 4-c), and a valve core to permit placing a pressure charge in the bellows before the free piston is placed in service. The bellows is the main control unit of the free piston and performs two function: 1. It governs the opening and closing of the sleeve valves. a.: dictated by the producing activities of the well in which the piston is operating. 2. In its normal position, it holds a rubber packer in an elongated position to permit passage of fluid between the packer and the tubing walls. The lower section of the free piston contains a hydraulic shock absorber which cushions the return of the tool to its

Jan 1, 1953

By G. W. Binkley, G. K. Dumbauld, F. A. Brooks, B. E. Morgan

In recent years, oil well cementing compositions have been developed with low densities, controlled set strengths, and satisfactory thickening times. With the introduction of the permanent-type well completion method for cementing wells, another property—that of rate of filtration or water loss to permeable formations— has become important. Laboratory data show that cement slurries prepared with oil, water, bentonite, and calcium lignosulfonate possess satisfactory thickening times, strengths, and filtration properties for primary cementing of casing and for squeeze cementing with the permanent-type well completion technique. Cementing compositions have been prepared with oil-in-water emulsions varying in composition from 60 cc water and 20 cc oil per 100 gm cement to 90 cc water and 45 cc oil per 100 gm cement. These compositions have contained from 0.4 to 5.0 per cent calcium lignosulfonate by weight of dry cement. Slurries prepared from these compositions weigh 11.4 to 13.1 lb/ga1 and have filtration rates of from 10 cc to approximately 100 cc in 30-min API tests at room temperature. The unfiltered emulsion cements develop one-day tensile strengths of 60 to 220 psi; and the filtered mass sets to tensile strengths of 60 to 150 psi in 12 hours and develops strengths of 320 to 515 psi in seven days when cured at 125° F. Field experience gained from 13 field mixing jobs demonstrates the utility of the emulsion cement for permanent-type squeeze cementing operations. INTRODUCTION In recent years, research in oil well cementing composition has been directed toward the development of cements having low densities, controlled set strengths, satisfactory thickening times, and low rates of water loss by filtration. Two well cementing compositions that have been developed with these properties are the modified cements containing, respectively, 12 and 25 per cent bentonite clay and various concentrations of calcium lignosulfonate1,2 In a search for other ways to incorporate these characteristics in a cementing composition, consideration was given to the rheological properties of oil-emulsion drilling fluids. Many of the desirable properties observed in oil-emulsion drilling fluids are equally advantageous in a cementing composition. For example, low water loss by filtration and low density, which are inherent characteristics of these oil-in-water emulsions, are desirable for many oil well cementing operations. Furthermore, oil-emulsion slurries have lubricating properties similar to those of oil-emulsion muds, a factor which should provide ease of rotation of casing during primary cementing operations. The properties of lubrication and low filtration may be of special value in both primary and squeeze cementing operations encountered in slim-hole drilling. Studies in the preparation of oil emulsion systems have pointed out the need for violent agitation in order to disperse the oil into the water phase. It was thought, therefore,

Jan 1, 1957

By R. H. Jacoby, V. J. Berry

Future depletion performance and ultimate oil recovery from reservoirs producing under volumetric control are often predicted with the aid of a material balance equation. When the reservoir fluid is very volatile, however, certain assumptions implicit in the use of the conventional methods are no longer valid. This is became laboratory differential vaporization test procedures do not adequately represent the reservoir depletion process and the performance of surface separation facilities. In such cases recovery of stock tank oil per unit of pressure decline can be predicted only from a detailed knowledge of the separator conditions and the over-all composition of the fluid entering the wellbore at each stage of depletion. Surface recovery is not simply related to the total quantity of liquid flowing into the well under reservoir conditions. In order to improve predictions for reservoirs which produce volatile oils, a step wise method of calculation has been developed. This method uses relative permeability data and multicomponent flash calculations to predict oil and gas production as a function of reservoir pressure. Calculations are presented for a reservoir containing a volatile crude oil, and predicted tank oil recovery by primary depletion is more than twice that predicted by conventional methods which are known to be adequate for ordinary black crude oils. Calculated maximum produced gas-oil ratio is less than one-fourth of the conventional prediction. Wellstream compositions have also been used to determine variation in stock tank oil composition and liquid content of the separator gas. This information is of particular importance for crude stabilization calculations and for design of gasoline plant facilities to recover LPG and natural gasoline. INTRODUCTION The estimation of oil reserves and the prediction of future recovery performance of petroleum reservoirs is a frequent task of the petroleum engineer. If the reservoir produces under volumetric control, performance calculations for primary depletion are made by combining oil and gas material balances with the gas-oil flow characteristics of the reservoir rock. For black oil reservoirs, the Schilthuis1 type material balance is commonly employed. For gas or gas-condensate reservoirs, where only one phase is flowing under bottom-hole conditions, a more simplified material balance is used. In the period in which these material balance methods were conceived and put into practice, it was common to classify reservoirs according to the type of fluid produced as (1) black oil reservoirs, or (2) gas or gas-condensate reservoirs. Recently, however, deeper drilling and more extensive studies of reservoir fluid properties have led to the recognition of reservoir fluids with phase characteristics between those of ordinary black oils, and gases or gas-condensate fluids. These intermediate fluids contain relatively large amounts of the hydrocarbons ethane through decane and are found in deep, high temperature (250°F) reservoirs. Such fluids are often referred to as high shrinkage crudes or "volatile oils." They are usually characterized by tank oil gravities above 45° API. high solution gas/oil ratios,

Jan 1, 1958

By Dwight K. Smith

A new pozzolanic composition has been developed for cementing oil wells where moderate to high temperatures prevail. This material is an entirely different concept to other oil well cementing materials, such as portland cements, cements containing additives, or liquid resins. Its characteristics are such that it is not, at present, recommended for use at temperatures less than 140º F. It can he either accelerated or retarded across a wide range of well conditions. This new cement is composed of a pozzolanic material, hydrated lime, and a chemical activator to give it early initial strength. This material can be used in wells from 6,000 to 18,000 or more feet where temperature conditions are similar to those along the Gulf Coast. This cement, when set, has no soluble portion subject to leaching or any compounds that should be attacked by sulfate waters or brines. For this reason, it should be permanent when placed adjacent to formations carrying any type of fluid. The compressive strengths in 24 hours are more than adequate for wells where temperatures are 140°F and higher. These values ore in excess of many other types of cementing composition presently in use in the field. This pozzolanic composition does not retrogress in strength at high temperatures as do some other types of cementing materials. The slurry weights of this material will vary slightly according to the specific gravity and water requirements of the pozzolnn itself. The materials covered herein will mix from 13.5 to 14.3 lb/gal, and will have a waiting-on-cement time comparable to other materials used under the same conditions. Economically speaking, this composition is less expensive than either portland cements or retarded cements presently being used under deep well conditions. INTRODUCTION Pozzolans are siliceous material which, though not cementitious in themselves, contain constituents which at ordinary temperatures will combine with lime in the presence of water to form compounds which have a low solubility and possess cementing properties. The use of pozzolanic materials dates back many hundreds of years and both the ancient Greeks and Romans were aware that certain volcanic deposits, if finely ground and mixed with lime and sand, yielded a mortar which possessed special properties. Generally, the early strengths of such materials were rather weak and were considered insufficient for modern commercial usages. Pozzolanic materials have been used extensively with portland cement in mass concrete to obtain special properties. In recent years, large quantities of certain pozzolanic materials have been used successfully admixed into portland cements for oil well cementing. Pozzolans, being reactive silicates, will combine with the free lime that is an inherent component of set portland cements and thereby. becomes cementitious themselves. POZZOLANS FOR OIL WELL CEMENTING There are many types of pozzolans, some of which are more reactive than others. The quality of the pozzoIan depends on the degree of reactivity, chemical composition, fineness, and other less well understood factors. Some of the more widely accepted pozzolans are those classified as fly ashes, while others are certain materials of volcanic origin. pozzolans which require large vol-

Jan 1, 1957

By Arthur Lubinski, K. A. Blenkarn

It is explained why the bottom portion of freely suspended tubing in a pumping well buckles and straightens in succession during the pumping cycle. Field evidence of resulting rod-on-tubing wear, excessive polished rod load, and excessive horsepower are given. The possibility that buckling hastens pump wear is strongly suggested. Means for either prevention of buckling or for mini-mizing its effects are explained, their relative merits compared, and field results of their use given. These means are: tension anchors, tail pipe, sucker rod guides, and corrosion inhibitors. Charts and formulas for best use of tension anchors, tail pipe, and guides are given. Use of tension anchors, or compression anchors with a heavy tail pipe, prevents both buckling and breathing, thus improving volumetric efficiency. Without tail pipe, buckling above compression anchors precludes such improvement. INTRODUCTION It is well known that a column must be subjected to some compression in order to buckle; and also that a structural member does not buckle if subjected to a tension. When consideration is given to a tubular column, the question may be asked, "How is the buckling phenomenon affected by inside or outside pressure?' At first, it seemingly should not be affected. However, this is not so. In order to arrive at a correct deduction one should first understand the basic reasons for buckling of a column under loading*. Then he should add to the effect of that loading the effect of pressure. Following this procedure, one may discover quite unexpected phenomena. In some cases, when subjected to more pressure inside than outside, a pipe may buckle under tension. In other cases, a pipe may remain straight, although subjected to a very large compression. In 1950 and 1951 it was explained why the bottom portion of a string of pipe freely suspended in a well does not buckle even when subjected to a large compression due to buoy- ancy.2,3 It was shown that the com-monly used concept of a neutral point, as being a point in the string with neither compression nor tension, is inadequate, and a more relevant definition of the neutral point was introduced. The findings were also generalized to cases of different pressures inside and outside a pipe.3a Later, in a further generalization, allowance was made for variations of stress and pressure with depth.' The findings were applied to the new technique of hydrostatic high pressure testing of lengths of pipe in the mill.5 In 1952 it was observed that previous theoretical findings apply to tubing in pumping wells. The lower part of freely suspended tubing buckles during the upstroke portion of the pumping cycle. Later, it was ascertained that this phenomenon is responsible for wear and malfunctioning of the equipment. Various remedial measures were devised and successful field trials conducted. Only brief mentions on the subject have been published.6,7 In this paper, the phenomenon of tubing buckling is explained, field

Jan 1, 1958

By G. G. Priest, B. E. Morgan

The production of oil and gas from wells is often seriously hindered by the compaction of solids in the perforations during the perforating process. To realize the full productive capacity of a well, it is necessary either to remove the plugging material from the perforations or to perforate in a manner which does not cause plugging of the perforations. The latter method can be accomplished by having a non-plugging fluid in the casing at the time the well is perforated. This paper describes the results of laboratory tests, perforating tests, and experimental field tests which demonstrate that certain emulsions serve effectively as non-plugging perforating fluids. The principal components of these emulsions are two liquids: an aqueous phase consisting of a solution of either sodium chloride or calcium chloride, and an oil phase consisting of diesel oil, tetrachloroethylene, or a combination of both. Small amounts of other agents which serve to stubilize the emulsions, to reduce the fluid loss, and to inhibit corrosion are also present. The density of the emulsions is controllable within the range of 7.5 to 12.5 lb/gal; no insoluble solids are present, the filtration rate is low, and the thermal stability is satisfactory at temperatures as high as 200°F. The corrosion of steel by these emulsions is negligible. Tests conducted under conditions which simulate the temperature and the pressure in an actual well demonstrate that these emulsions fulfill the requirements of a non-plugging perforating fluid. In addition, lirnited field experience furnishes evidence that these emulsions remain in position after they are spotted, that they are retained in the casing after the perforations are made, and that they are easily removed from the perforations when the well is opened for production. When the pressure in the borehole is greater than the formation pressure at the time a well is perforated, plugging of the perforations can be avoided by spotting an emulsion adjacent the interval to be perforated. This procedure should eliminate low well productivity caused by plugging the perforations. INTRODUCTION Nature of Problem The most widely used method for the completion of oil and gas wells is to set and cement casing through productive horizons, and then to obtain production by gun-perforating the section of casing opposite the desired interval. This method is gen- erally successful and it was thought at one time that those failures which did occur were due to insufficient penetration by the perforator. Despite recent improvements in perforators which assure ample penetration, unsatisfactory fluid production continues to be a problem. Evidently, the trouble comes from some other source. Recent results obtained by Allen and Worzel1 demonstrated that low fluid productivity may be caused by the perforating process and/or by the fluid in the wellbore at the time of shooting. They found that perforations are often completely plugged by debris from the perforator, pulverized sand from the formation, and compacted solids from the drilling mud when the pressure in the wellbore is greater than the pressure in the formation at the time of perforation. In some cases a differential pressure in excess of 400 psi was required to initiate flow into the well through these plugged perforations. The plugging of perforations by solids not only causes low productivity from wells, but it creates simultaneously other problems in the production of oil and gas. For example, when most of the perforations are plugged, high rates of flow must occur through the few perforations that are open. The resulting high pressure drop may cause production

Jan 1, 1958

By P. R. PaeIay, A. Slibar

Using three-dimensional, stress-deformation rate equations for a Bingham plastic, an approximate solution for the laminar flow of drilling mud between the drill pipe and casing is given for the case when the velocity gradients due to axial flow are large compared to velocity gradients due to rotation. INTRODUCTION The fact that drilling mud can be treated, to a first approximation, as a Bingham plastic has been established by several investigators12,3,4,5. A Bingham plastic is a material that is rigid until a certain combination of stresses exceeds a critical value. When the stresses are sufficiently high to initiate flow, the reduced stresses have a constant ratio to the corresponding deformation rates at each point. Prediction of pressure and torque requirements to produce the desired flow of the material have been made by analytical solutions due to Bingham6, Reiner7, and Buckingham8. One part of the present means of calculation that requires clarification is the flow between the drill pipe and casing. Present methods treat the flow resulting from the rotation of the drill pipe separate from the flow produced by the axial pressure gradient. Since the non-linear behavior of a Bingham plastic implies that solutions cannot be superposed, the present analytical investigation was undertaken to obtain a solution to the problem of combined axial and tangential flow. Equations have been proposed for the three-dimensional flow of a Bingham plastic9,10,11 and it has been shown that the proposed equations lead to the usual solutions from the one-dimensional theory". Applying these equations to the flow between two concentric cylinders the problem of axial flow only13 and tangential flow only12 have been solved. In addition to the separate problems of axial and tangential flow between concentric cylinders, the authors have determined the relationship between external torque on the inside cylinder and axial pressure gradient necessary to initiate flow". The solution given in Ref. 14 points out the complexity of the present problem. The problem considered here is the case of simultaneous axial and tangential flow. The axial flow, necessary to keep the drill bit free of removed material, results from the axial pressure gradient. Tangential flow is present since the drill pipe rotates in the hole. The solution given here is valid when the shear stresses in the drilling mud due to rotation are small compared to the shear stresses resulting from the axial flow. This case for laminar flow can be encountered in oilfield drilling. STRESS-DEFORMATION RATE EQUATIONS A detailed derivation of the equations governing the behavior of a Bingham plastic is given in Ref. 10. This section briefly outlines the physical reasoning leading to this three-dimensional formulation of the stress-deforma-tion rate law. Experiments on a certain class of materials have demonstrated the following properties: (1) when a certain combination of the stresses is below a critical value no deformation of the material occurs, (2) to a first approximation this combination of stresses is independent of the hydrostatic pressure (negative average normal stress), (3) if flow occurs the ratio of the reduced stress to the corresponding deformation rate is constant at each point of the flowing material, and (4) incom-pressibility. For the one dimensional case of shear deformation, Bingham6 formulated the governing equation as dxx, = 0 for sxx < to and µdxx = s xx = to for sxx to , . where dxx is the shear deformation rate, sxx the shear stress, to the critical shear stress, and p the slope of the sxx vs dxx curve for dxx > 0. Fig. 1 shows the behavior for pure shear between two parallel plates. Taking into account the physical properties given above and assuming the critical combination of stresses to be measured by the octahedral shear stress, the fol-lowing three-dimensional equations have been proposed.

Jan 1, 1958

By A. J. Teplitz, T. Bardeen

In the course of an investigation of lost circulation, a new tool has been developed which gives a qualitative measure of the relative velocity between the fluid column in the borehole and the tool. The position of a diaphragm in the side wall of the instrument depends on the flow through the device. This position is established by using the conductive borehole fluid in a potentiometric circuit. The instrument has high sensitivity and can detect changes in velocity as low as. 5 ft/min. Lost circulation mud additives do not interfere with the satisfactory performance of the tool. In a number of circulation losses of the pressure induced type, the instrument has shown that the losses were confined to extremely narrow zones (less than I ft), indicating that such ruptures occur in a more or less horizontal rather than vertical plane as has often been assumed. This pinpointing of the zone of loss is important in remedial procedures since it allows the treatment to be applied directly to the point of loss rather than to the entire open hole. The device can also be employed for indicating points of entry of water in producing wells. INTRODUCTION The need for an improved means of locating the positions of lost returns zones became evident during an investigation of lost circulation difficulties in the Gulf Coast area.1 With instrumentation available at the time, it had been learned that, contrary to common belief, the position of the thief zone responsible for a given loss seldom coincided with the point of bit penetration at the time the loss was encountered. In the majority of cases, the losses were found to be occurring at some distance removed from the bottom of the hole —sometimes as much as a few thousand feet. This information, along with other observations made during the investigation, led to improved techniques&apos; for dealing with lost circulation problems. Highlighted, however, among the results of this work and of similar studies subsequently conducted in drilling operations in other parts of the country, was the indication that a considerable portion of the difficulty and expense involved in treating prolonged circulation losses is due to the unsystematic application of remedial measures to one or more apertures of unknown position. Basis of Tests It is worth considering that if the troublesome formation could somehow be transported to the surface where it could be directly observed, there would likely be little difficulty in readily effecting a seal. Although this is a decided oversimplification of the situation, it does appear that the chief obstacles to similar ease of handling of a lost circulation zone in a well are lack of visibility and of ready accessibility. The latter handicap is overcome to a considerable extent by placement techniques already in use, and other procedures now in the process of development are expected to offer further improvement. But in the matter of visual observation, the technique to be presently described appears to afford a quite satisfactory substitute.

Jan 1, 1957

By Blake M. Caldwell, Thomas C. Poulter

A new approach to an old problem has made it possible to do in a a tively short period what has not been accomplished in the past three quarters of a century using strictly experimental methods. A theoretical study was made of the underlying principles whereby a jet is formed by a shaped charge and of the mechanism of the penetration of the target by that jet. It was found that there are more than 10, and perhaps as many as 15 variables affectin!? the performance of the shaped charge. Only a few calculations are necessary to show that it is physically impossible to investigate all of these variables experimentally. The shaped charge theory has been extended to include a previously little-understood mechanism in high explosive phenomena; namely, low order detonation. By superimposing a high order detonation on a zone already undergoing low order detonation, all appreciable improvement in performance is accomplished. The development of a design wherehy these phenomena are coordinated in such a way as to develop a jet which is tailored to meet the specific target requirement will be described in detail. The shortcomings or even impossibility of strictly experimental techniques will be illustrated by a discussion of the development of a special-purpose explosive charge. INTRODUCTION In an article appearing in the May, 1888 issue of Scribner&apos;s Magazine, Charles E. Monroe described his early experiments with gun cotton (Fig. 1) which led to his name being most fre-quently connected with our present-day shaped charge. Although the sunken letters or "cavities" in Mon- roe&apos;s gun cotton were not lined, they produced some penetration of an iron plate. The credit for the lined shaped charge, however, should rightfully go to Dr. R. W. Wood of the Physics Dept. of Johns Hopkins University, who was responsible for first discovering the fact that a metal liner in a cavity of explosive gave high velocity fragments and/or jets of metal. This discovery was made by Dr. Wood inadvertently while investigating an accidental death resulting from an electric blasting cap. He discovered that a jet of high velocity copper particles was ejected from the dimple

Jan 1, 1958