Drilling hook

Figure 4-23. Drilling hook [10]. Figure 4-23. Drilling hook [10].
Velocity. The velocity of the drilling fluid is a major problem in air and gas drilling operations (see section titled Air and Gas Drilling ). High gas velocity (i.e., 8,000 ft/min) is maintained during dry gas drilling. The high annular velocities are necessary for dry-gas drilling fluid to function properly. Therefore, alternative drilling fluids should be considered if corrosion problems are severe. Stable foam can perform effectively at reduced annular velocity such as 2,000 ft/min or lower.  [c.1326]

On a rock bit, the three cones are rotated and the attached teeth break the rock underneath into small chips ( cuttings ). The cutting action is supported by powerful jets of drilling fluid which are discharged under high pressure through nozzles located at the side of the bit. After some hours of drilling (between 5 and 25 hours depending on the formation and bit type), the teeth will become dull and the bearings wear out. Later on we will see how a new bit can be fitted to the drill string. The PDC bit is fitted with industrial diamond cutters instead of hardened metal teeth. This type of bit is becoming increasingly popular because of its better rate of penetration, longer life time and suitability for drilling with high revolutions per minute (rpm) which makes it the preferred choice for turbine drilling. The bit type selection depends on the composition and hardness of the formation to be drilled and the planned drilling parameters.  [c.37]

Until downhole motors became available a whipstock (Fig. 3.15) which is a slightly asymmetric steel joint, was inserted in the drill string. The assembly is oriented downhole and a rathole is drilled which is then enlarged to full bore hole size. The technique is still used in wells where hole conditions e.g. high temperatures, are unsuitable for downhole motors (see below).  [c.46]

Mud motors in general have several advantages over the rotational directional drilling methods. They provide a full gauge hole, dog legs are more likely to be smooth and the penetration rate is usually high. Torque is transmitted more effectively to the bit since the whole drill string is not rotated. This is particularly advantageous In long reach, highly deviated wells. Downhole motors may cause problems if losses occur and lost circulation material needs to be pumped, as this may plug up the motor.  [c.48]

High deviation angles (above 60°) may cause excessive drag or torque while drilling, and will also make it difficult to later service the well with standard wireline tools.  [c.49]

A special version of slim hole drilling currently emerging as a viable alternative is co//ed tubing drilling (CTD). Whilst standard drilling operations are carried out using joints of drill pipe, coiled tubing drilling employs a seamless tubular made of high-grade steel. The diameter varies between 1 3/4" and 3 1/2". Rather than being segmented the drill string is reeled onto a large diameter drum.  [c.53]

Carbonate rocks are more frequently fractured than sandstones. In many cases open fractures in carbonate reservoirs provide high porosity / high permeability path ways for hydrocarbon production. The fractures will be continuously re-charged from the tight (low permeable) rock matrix. During field development, wells need to be planned to intersect as many natural fractures as possible, e.g. by drilling horizontal wells.  [c.85]

The main cost factor ot coring is usually the rig time spent on the total operation and the follow up investigations in the laboratory. Core analysis is complex and may involve different laboratories. It may therefore take months before final results are available. As a result of the relatively high costs and a long lead time of core evaluations the technique is only used in selected intervals in a number of wells drilled.  [c.129]

The skin term represents a pressure drop which most commonly arises due to formation damage around the wellbore. The damage is caused by the invasion of solids from the drilling mud or from the cementing of the casing. The solid particles partially block the pore space and cause a resistance to flow, giving rise to an undesirable pressure drop near the wellbore. This so called damage skin may be removed by backflushing the well at high rates, or by pumping a limited amount of acid into the well acidising) to dissolve the solids. Another common cause of skin is partial perforation of the casing across the reservoir which causes the fluid to converge as it approaches the wellbore, again giving rise to increased pressure drop near the wellbore. This component of skin is called geometric skin, and can be reduced by adding more perforations. At very high flowrates, the flow regime may switch from laminar to turbulent flow, giving rise to an extra pressure drop, due to turbulent skim, this is more common in gas wells, where the velocities are considerably higher than in oil wells.  [c.216]

The efficiency of gas turbines is limited by the maximum allowable turbine inlet temperature (TIT). The TIT may be increased by cooling of the blades and vanes of the high pressure turbine. Cooling channels can be casted into the components or may be drilled afterwards. Non-conventional processes like EDM, ECD or Laser are used for drilling. Radiographic examination of the drilled components is part of the inspection procedure. Traditional X-Ray film technique has been used. The consumable costs, the waste disposal and the limited capacity of the two film units lead to the decision to investigate the alternative of Real-Time X-Ray.  [c.453]

The first example refers to the detection of a 1mm side drilled hole at a depth of 45 mm in a polyethylene plastic material. Due to the high sound absorption in plastics, a low operating frequency is chosen. A probe having a 1 MHz element of 24 mm diameter was selected for this example. The echo pattern of a conventional probe with a PZT transducer is pre-  [c.709]

Procedures investigated for removal of explosives and propellants from munitions include the use of steam (qv), low pressure hot water jets, high pressure hot or cold water jets, and high pressure water at supercritical temperature and autoclave melting. Organic solvents have been used for extraction and reclamation of soluble components from polymeric explosives and propellants. Similarly, supercritical fluid extraction uses high pressure to convert compounds that are gases at atmospheric pressure and ambient temperatures, eg, carbon dioxide and ammonia, to Hquids. The fluids are then used at elevated temperatures and pressure to extract stabilizers, plasticizers (qv), and acetate esters from nitrocellulose propellants or ammonium perchlorate from composite propellant. After extraction, the pressure and temperature are reduced and the Hquid reverts to its gaseous state. These procedures may be supplemented with mechanical methods such as saws, presses, and drills to faciUtate the recovery process, particularly for large rocket motors  [c.8]

The halogen fluorides offer an advantage over fluorine in that the former can be stored as Hquids in steel containers and, unlike fluorine, high pressure is not requited. Bromine trifluoride is used as an oxidising agent in cutting tools used in deep od-weU drilling, whereas chlorine trifluoride is used to convert uranium to UF in nuclear fuel processing (see Nuclear reactors Petroleum).  [c.184]

The development of diagnostic tools coupled with high speed computers is increa sing the probabiUty of locating specific gas-rich formations. Drilling technology such as directional drilling affords the opportunity to place a weU-bore strategically with respect to either naturally occurring or iaduced fractures. More sophisticated representations of reservoirs and rock mechanics should improve well stimulations, and more cost-effective recovery of a specific resource. The continued development of coal seams as a source of natural gas is an example.  [c.176]

Drilling and Field Development. The techniques for drilling hydrothermal weUs have been adapted from those in use in the oil and gas industry (7) (see Gas,natural Petroleum). Rotary drilling rigs are normally employed along with conventional drilling equipment such as steel casing, drilling lubricants, and casing cements. Drilling conditions encountered in geothermal areas are often more severe than those in oil fields, although, in some instances, soft sedimentary rock of the type common in oil and gas basins is encountered. Usually it is necessary to bore through extremely hard metamorphic or igneous rock, resulting in a slower drilling rate. Penetration rates of 5—13 cm/s (10—25 ft/h) are common, but frequently problems such as loss of circulation, caving, twist-off, and high pressure flow zones related to the rock formation cause intermptions. In addition, the temperatures encountered in drilling into hydrothermal reservoirs are usually considerably higher than those for oil and gas well drilling. Thus extra cooling procedures and special lubricant formulations must be employed. Moreover, geothermal drilling is subject to more stringent regulations than oil and gas drilling. The costs of drilling geothermal wells are from 2—4 times greater than those for oil and gas wells.  [c.264]

Hydrothermal drilling fluid, or mud, typically consists of a suspension of coUoidal bentonite clay in water. It is circulated through the wellbore to lubricate and cool the drill bit as well as to carry the cuttings to the surface. Because drilling mud is relatively expensive, it is continually treated and reused to minimize the total volume of fluid consumed. Commonly, the mud is stable to about 150°C, but it tends to gel at higher temperatures as the clay particles flocculate. Boiling of the mud as it comes to the surface can also be a problem. The incorporation of air to increase the surface area of the mud (aeration), active cooling at the surface, pressure control so that any flashing to steam can be confined to a specially designed separator, or combinations of these techniques may be used to alleviate problems related to high wellbore temperatures. Sometimes special high temperature sepioHte clays or synthetic polymers may be substituted for bentonite, but these significantly increase the unit cost of drilling muds. In steam-dominated hydrothermal reservoirs, it is desirable to substitute air for the water-based drilling fluid in the region of the steam production in order to prevent the fluid from plugging fractures through which the steam issues. Not only is the air a poorer lubricant, but the cuttings can cause rapid abrasive degradation of drill string components as they are brought to the surface in the high velocity air stream. Therefore, air drilling is avoided except in special circumstances.  [c.264]

Logging operations, in which drilling is temporarily suspended while instmments are lowered into the weUbore to make measurements, are very important in geothermal weU drilling operations. The temperature, flow rate, and pressure of any fluid located can be deterrnined and used as the basis for further drilling decisions. Hydrothermal drilling is often carried out in rough mountainous areas, and the terrain alone presents special problems in weU and field development. Considerable costs can be incurred in preparing flat drilling pads therefore, several weUs may be directionally drilled from a single pad to reach different parts of the hydrothermal resource. Geothermal fluids have a low unit value relative to oil and gas thus a geothermal weU must be operated at a much higher flow rate to be profitable. This means that either the weUs must be of greater diameter or flow rates must be considerably higher. Larger diameter weUs become ever more expensive to drill, and high flow rates can lead to increased rates of abrasion and more rapid deterioration of piping. In addition, hydrothermal fluids that contain significant amounts of dissolved soHds or corrosive gases can rapidly degrade piping. These effects can be  [c.264]

The geothermal drilling industry is much smaller than that of oil and gas drilling and the active geothermal rig count is generally less than 10. Thus, there is not a commercial basis for the development of specialized materials and equipment for geothermal drilling. For a number of years, the U.S. Department of Energy has sponsored the development of high temperature drilling fluids and cements especially designed for geothermal operations (9). Efforts have been concentrated on lightweight, carbon dioxide-resistant cements, thermally conductive and scale-resistant protective liners, improved materials to control lost circulation, and bonding agents.  [c.265]

Economics. The cost of energy from the Pleasant Bayou plant, at 12—180/kWh, was not competitive with the 4—60/kWh power produced from higher quaUty fossil fuels which are abundant in the Gulf Coast area (33). The high costs can be related to a number of factors. The multiple energy forms, each effectively requiring its own generating plant, result in higher capital costs. Additionally, the salinity of the fluid leads to problems in corrosion and scaling as well as in disposal. EinaHy, the depth at which the resource exists means that drilling costs are high. These factors are fundamental characteristics of the technology which, except for corrosion and scaling, are not readily amenable to solutions that are economical with the technology available today. Commercial utilization of geopressured resources for electricity production is not expected in the foreseeable future.  [c.269]

Economics. The costs of developing HDR resources are closely tied to the depth at which sufficiently hot rock is found. This is most readily expressed in terms of the geothermal gradient shown in Figure 9. High gradient resources are located primarily west of the Mississippi River. In the eastern United States, it is generally necessary to drill much deeper to reach hot rock. Because drilling is the most expensive single factor in HDR development, the first HDR electric plants are expected to be built in the western United States.  [c.272]

High power laser beams can vaporize material, leading to appHcations such as hole drilling and cutting. Higher power densities are used for these appHcations than for hardening and welding. Hole drilling in ceramic materials has become common. There is a need for small (less than 0.5-mm) holes in the alumina substrates used in many electronic appHcations (see Integrated circuits). Holes drilled before the ceramic is fired, tend to change dimension during firing. After firing, the material is very hard, brittle, and difficult to drill by conventional techniques. Laser drilling offers an improved technique for producing holes in the fired ceramic, and has become an important appHcation for lasers in the electronics industry.  [c.13]

Applications. The high heat tolerance and good salt compatibiUty of welan gum indicate its potential for use as an additive in several aspects of oil and natural gas recovery. Welan also has suspension properties superior to xanthan gum, which is desirable in oil-field drilling operations and hydraulic fracturing projects. It is compatible with ethylene glycol, and a welan—ethylene glycol composition that forms a viscous material useful in the formulation of insulating materials has been described (244).  [c.299]

An early appHcation of molybdenum was its substitution for tungsten in the high speed steels popular before World War I. The red hardness of a steel containing 9% molybdenum is as high as that of a steel containing 18% tungsten. Subsequentiy, a series of high speed steels containing 3.75—9.5% molybdenum was developed. Substantially all hacksaws and twist drills made in the United States are manufactured from molybdenum-containing high speed steels.  [c.467]

Operating companies and regulatory agencies (qv) have a vital responsibiUty for specifying and managing the use of nondestmctive testing during erection and service of costiy faciUties and systems such as chemical plants, petroleum refineries, off-shore drilling platforms, nuclear power plants, and transport systems where failures during services are potentially disastrous. Effective in-service nondestmctive tests of materials and additional nondestmctive tests made during maintenance (qv) shutdown periods can permit eady detection and subsequent correction of hidden damage or deterioration (see also Materials reliability Materials standards and specifications). Such test programs provide protection for the pubhc, as well as for corporations and management from failure costs and penalties, which can include high litigation and insurance costs (7—10).  [c.123]

Important sources, e.g. in South Africa, are the basic igneous rock known as kimberlite and also alluvials. The valuable diamond may be colourless or faintly coloured, but must be transparent. The heavily coloured forms, known as carbonado or bort, are of no value as gems, but are used for rock drills, for lathe tools, and when powdered for cutting and polishing clear diamonds. In cutting, the natural crystalline form is obliterated and an artificial shape, which gives rise to a large amount of internal reflection producing the fire of the stone, produced. The diamond is extremely hard, and stands highest in Mohs s scale of hardness. It possesses a high refractive index, and dispersive power. It is relatively much more transparent to X-rays than are its imitations. World production 1979 48 MKT, 62-5% southern Africa including Zaire.  [c.132]

The amount of time needed for planning, acguiring, processing and interpreting seismic data should not be under-estimated. Cycle times of 2 years are not untypical for 3D surveys in the North Sea (i.e. from conception to final interpretation), but major efforts are underway to improve on the time reguired. More sophisticated efforts, such as prestack migrations, and complex seismic inversion, reguire longer cycle times, sometimes doubling these. The cost of seismic depends on the complexity of the survey, but typically varies from 10,000 (simple, marine) - 40,000 (complex, land) per square km for 3D acquisition and 5,000 - 15,000 for processing. 3D surveys can be any size from 100 to 2,000 square kilometres or more. However, the determining economic factor is often the ratio to well cost. Marine wells can be extremely expensive, (North Sea wells, typical cost of the order of 16 million) but on land drilling is much cheaper. For this reason huge 3D surveys are general offshore and engineers are more inclined to use seismic as a substitute for drilling if possible (e.g. in appraisal).  [c.23]

Figure 2.14 shows an example of a basic mudlog, including information about the drilling rate, cuttings and hydrocarbon shows . The sands clearly show up on both the drilling rate and the cuttings description. Oil stains were observed in the cuttings, and the gas detector gives high readings and indicates the presence of heavy components in the gas. This example illustrates that the value of a mudlog lies in the combination of the information received from the various sources.  [c.27]

After the drilling has progressed for some time, a new piece of drill pipe will have to be added to the drill string (see below). Alternatively, the bit may need to be replaced or the drill string has to be removed for logging. In order to pull out of hole , hoisting equipment is required. On a rotary rig this consists of the hook which is connected to the travelling block. The latter is moved up and down via a steel cable block Und ) which is spooled through the crown blockon to a drum draw workd ). The draw works, fitted with a large brake, move the whole drill string up and down as needed. The derrick or mast provides the overall structural support to the operations described.  [c.38]

Most reservoirs are characterised by marked lateral changes in reservoir guality corresponding to variations in lithology. Computing tools now becoming commercially available allow the modelling of expected formation responses ahead of the bit . This is possible In areas where a data set of the formations to be drilled has been acquired in previous wells. The expected gamma ray (GR) and density response is then simulated and compared to the corresponding signature picked up by the tool. Thus, in theory, it is possible to direct the bit towards the high quality parts of the reservoir. Resistivity measurements enable the driller to steer the bit above a hydrocarbon water contact, a technique used, for example to produce thin oil rims. These techniques, known as geosteering, are rapidly developing and are increasingly being applied to field development optimisation. Geo-steering also relies on the availability of high quality seismic and possibly detailed palaeontological sampling.  [c.50]

Introduction and Commercial Application-. This section introduces the main methods used to convert raw well data into useful information information with which to characterise the reservoir. A huge volume of data is generated by drilling and logging a typical well. Collecting and storing data requires substantial investment but unless it is processed and presented appropriately much of the potential value is not realised. Describing a reservoir can be a simple task if it has been laid down as a thick blanket of sand, but becomes increasingly complex where hydrocarbons are found in, for example, ancient estuarine or reef deposits. In all cases however there are two main issues which need to be resolved firstly how much oil does the reservoir contain (the hydrocarbons initially in place - HCIIP), and secondly how much can be recovered (the ultimate recovery - UR). There are a number of ways to determine these volumes (which will be explained in Section 7.0) but the basic physical parameters for describing the reservoir remain the same  [c.136]

From this expectation curve, //there are hydrocarbons present (30% probability), then the low medium and high estimates of reserves are 20,48 and 100 MMstb. The NPV for the prospect for the low, medium and high reserves can be determined by estimating engineering costs and production forecasts for three cases. This should not be performed simply by scaling, but by tailoring an engineering solution to each case assuming that we would know the size of reserves before developing the field. For example, the low case reserves may be developed as a satellite development tied into existing facilities, whereas the high case reserves might be more economic to develop using a dedicated drilling and production facility.  [c.328]

In the case of attic/cellar oil, and isolated fault blocks or layers it is clearJhat hydrocarbon reserves will not be recovered unless accessed by a well. The economics of the incremental infill well may be very straightforward a simple comparison of well costs (including maintenance) against income from the incremental reserves. Reserves which have been bypassed by a flood front are more difficult to recover. Water will take the easiest route it can find through a reservoir. In an inhomogeneous sand, injected water or gas may reach producing wells via high permeability layers without sweeping poorer sections. In time, a proportion of the oil in the bypassed sections may be recovered, though inefficiently in terms of barrels produced per barrel injected. Drilling an infill well to recover bypassed oil will usually generate extra reserves as well as some accelerated production (of reserves that would eventually have been recovered anyway). To decide whether to drill additional wells it is necessary to estimate both the extra reserves recovered, as well as the value of accelerating existing reserves (Fig. 15.2).  [c.352]

In Fig. 2 an additional comparison with Lakestani (1992) is performed. This is a more difficult case because the centre depth of the crack is only 8 mm. It is still the pulse echo response from the lower edge of a 10 mm vertical strip-like crack that is shown. The probe has the size 20 mm by 22 mm, is of SV type with angle 60 and has centre frequency 2.04 MHz and an assumed bandwidth of 2 MHz. The calibration is by a side-drilled hole of diameter 9.5 mm and eentre depth 13 ram (the depth of the diffracting edge). The effects of the far field approximation for the probe is illustrated in the figure by giving curves for one, four and ten element probes. A single element probe is clearly insufficient although the peak location is correct and the peak value is only 6 dB too high. The difference between four and ten elements is for practical purposes negligible (the near field length of each element is less then 5 mm for the four element probe so this is not surprising). The agreement between UTDefect and the experiment is satisfactory, having in mind that the depth to the edge is about half the probe side so that the exact pressure distribution beneath the probe could be important.  [c.159]

These Systems were built for Westinghouse Hanford Company (WHC) for use in high level waste tank sampling operations performed by the Tank Waste Remediation Systems (TWRS) Project. A total of four, highly specialized Systems, designated as XRI-001 through XRI-004 by WHC are referred to on-site as the x-ray hot-dog carts. The systems are used to remotely image the inner contents of specially designed, 26-inch length, one and one-half inch diameter, stainless steel core sample tubes and the high level radioactive waste contents following the remote sample segments removal from underground waste storage tanks. A real time radiographic view (x-ray) of the sampler and it s contents are displayed on live video monitors, is video taped, and selected freeze-frame image views can be immediately printed in the field. These images allow the field operations personnel to directly monitor sample recovery volume and the waste s physical characteristics, e g., sludge, solid or liquid. This data provides a technical basis which allows the engineers to adjust the drilling/sampling platform operating parameters to optimize sample recovery efforts. Electrical power for x-ray systems (and all the associated sampling equipment) is provided by separate, portable diesel generators.  [c.610]

Polyacrylamides are used in many other oilfield appUcations. These include cement additives for fluid loss control in well cementing operations (127), viscosity control additives for drilling muds (128), and fracturing fluids (129). Copolymers [40623-73-2] of acrylamide and acrylamidomethylpropanesulfonic acid do not degrade with the high concentrations of acids used in acid fracturing.  [c.144]

Economics. In the early 1990s, the cost of electricity generated from geothermal energy varied from about 3.5—100/kWh (22). The cheapest electricity came from The Geysers, where steam can be deflvered to the power plant for less than 20/kWh of electricity generating potential (23). Electricity costs from hot-water resources using flashed steam and binary plants, respectively, are progressively higher. In addition to the usual power plant costs, other significant up-front capital costs, including resource exploration, drilling, and field development, must be covered before a geothermal plant can begin producing revenue. Accordingly, capital financing carries an added risk in geothermal projects because continued supply of fuel is not assured until considerable capital has been expended. Environmental concerns may also add to the capital costs of a hydrothermal plant. Hydrogen sulfide abatement systems can mn several million dollars. The exact costs vary with the composition of the gas to be treated. Liquid-dominated resources which are high in dissolved soflds incur added capital and operating costs to pay for the collection and disposal of the spent brine and any precipitated soHd residues.  [c.267]

The Technology. The basic technique for extracting energy from HDR was conceived and patented in the early 1970s (35). It is based on drilling and hydraulic fracturing technologies developed in the petroleum and geothermal industries. Eigure 10 shows an idealized HDR heat mine. The first step in constmcting a heat mine is to drill a well into sufficiently hot and impervious rock, with the exact depth of the well to be determined by local heat-flow and thermal conditions. Wells drilled for HDR appHcations are similar in many aspects to hydrothermal wells except that these wells are deeper and sometimes penetrate into a much greater depth of hard, crystalline rock. Eor this reason, specialized drilling and logging equipment which can withstand extended exposure to high temperatures is required. After the well has been completed, a segment of the bottom portion of the well is blocked off using a packer which provides pressure isolation. Water under high pressure is pumped through the packer and forced into joints in the surrounding rock body to form a reservoir consisting of a relatively small amount of water in a very large volume of rock. The extent of the reservoir region may be controlled by the pressure appHed via the injected fluid and the length of time the process is continued. The shape and orientation of the reservoir are functions of the natural jointing features of the host rock.  [c.270]

The project at Long Valley has been designed to proceed in four phases. Work on the first two stages of the project, which entailed drilling to 2313 m to reach rock at temperatures of 104°C, was completed in late 1991 (44). These depths and temperatures are typical of those seen in conventional hydrothermal drilling operations and the problems encountered by the project were not unlike those of other geothermal operations. The third phase of the work should extend the hole to a depth of 4267 m and temperatures of 300°C. Again, this drilling will not push beyond the frontiers of geothermal drilling technology. Phase four, however, is planned to complete the well at 6096 m into rock at 500°C, a temperature which is beyond the capacity of present technology. Drilling fluid additives are not stable at high temperatures, nor are casing cements. In addition, high temperatures cause more severe corrosion and available logging tools are expected to be limited. Insulated drill pipe, however, could allow water to be kept relatively cool as it is pumped to the bottom of a deep, hot magma well, and the development of insulated drill pipe has become a focus in the magma effort. The pipe envisioned would need to be double-waEed. The mechanical strength of such a pipe should not be a problem, but fabrication at reasonable costs and the development of an efficient insulated tool joint to connect the pipe segments present formidable development problems (see High temperature alloys).  [c.274]

Welan has similar properties to xanthan gum except that it has increased viscosity at low shear rates and improved thermal stabiUty and compatibihty with calcium at alkaline pH (90). The increased thermal stabiUty has led to its use as a drilling mud viscosifter especially for high temperature weUs. The excellent compatibihty with calcium at high pH has resulted in its use in a variety of specialized cement and concrete appHcations.  [c.437]

The limestone industry has achieved a high degree of mechanization since the 1960s, counteracting to some extent the general cost of inflation. The principal factors behind the productivity gains and cost saving have been use of larger earth-moving equipment in stripping operations improvement in speed, diameter, and depth of drilling with large rotary- and percussion-type drilling rigs equipped for inclined drilling expanded use of delayed action blasting widespread substitution of ANFO for dynamite in blasting use of mechanical or hydrauHc breakage in place of secondary blasting use of large shovels or buckets for quarry loading greater use of front-end loaders for quarry loading instead of shovels large capacity primary cmshers increasing use and efficiency of conveying systems, reducing tmck hauling in quarries vibratory screens replacing revolving screens increased diesel conversion of the electric power generation for the whole plant individual hoisting, earth-moving, and tmck equipment use of portable stone plants, providing greater production flexibility and increased use of computerized control systems in stone processing.  [c.170]

Accuracy and Dimensional Control. Electrolyte selection plays an important role. Sodium chloride, for example, yields much less accurate components than sodium nitrate. The latter electrolyte has far better dimensional control owing to its current efficiency/current density characteristics. Using sodium nitrate electrolyte, the current efficiency is greatest at the highest current densities. In hole drilling these high current densities occur between the leading edge of the drilling tool and the workpiece. In the side gap there is no direct movement between the tool and workpiece surface, so the gap widens and the current densities are lower. The current efficiencies are consequently lower in the side gap and much less metal than predicted from Earaday s law is removed. Thus the overcut in the side gap is reduced with this type of electrolyte. If another electrolyte such as sodium chloride solution were used instead, then the overcut could be much greater. Using soldium chloride solutions, its current efficiency remains steady at almost 100% for a wide range of current densities. Thus, even in the side gap, metal removal proceeds at a rate which is mainly determined only by current density, in accordance with Earaday s law. A wider overcut then ensues.  [c.309]

Large quantities of xanthan gum are used by the oil and natural gas industry in several aspects of hydrocarbon production (230,349) (see Gas, natural Hydrocarbons Petroleum). The high viscosity achievable at low concentration and the high suspending power efficientiy remove bit cuttings while reducing friction substantially throughout the drill string. Xanthan is compatible with many additives frequendy used to prepare drilling duids, and drilling duids can be made up of fresh, brackish, or salt water and stiU maintain viscosity. It can effectively thicken hydraulic fracture duids that are employed to improve porosity in subterranean formations, where viscosity is required to suspend a propping additive such as sand which is then pumped underground into newly formed fissures. The excellent heat stabiUty and salt compatibiUty frequendy result in its selection over lower cost viscosifiers. Xanthan is also added to solutions pumped underground that are used to displace oil toward a collection well. It improves the sweeping efficiency of these dooding duids enough to make them cost effective.  [c.303]

High Level Waste. Many studies have been made of possible modes of disposal for high level waste including spent fuel. Some of the techniques considered are a very deep hole, a remote island, mountainside, subseabed, the Antarctic ice sheet, and deUvery to space. As of this writing (ca 1995) the preferred method is deep underground burial in the floor of a mined cavity. Several types of rock have been considered as potential hosts to the waste, including granite, salt, basalt, and tuff. A history of high level waste disposal prior to 1987 is available (23). In the 1970s an investigation of the use of salt as disposal medium was undertaken, but terrninated when it was found that there had been extensive drilling in the region.  [c.230]

About half of the annual production of walnut-sheU and pecan-sheU flour, >1000 t/yr, is used in the plastics industry alone. Special machinery is required for grinding and transmitting the ground material because the dust from grinding is subject to spontaneous explosion. However, this ha2ard has largely been overcome by applying a fine spray of water to the shell flour as it leaves the grinder. Waste material from the pecan-shelling iadustry has shown commercial possibiUties for the recovery and production of oil and tannin shell flour as well as activated charcoal (45). Tannic acid produced from pecan shells is used by the tanning iadustry and by the oil industry to control the viscosity of drilling muds (see Petroleum). Because the United States has to import two-thirds of the tannin used in the leather industry, the extraction of this material from nutshells is of vital importance. After the extraction of tannin, the spent shells are used for making activated charcoal. Pecan shell, for instance, is an excellent material for the production of activated charcoal (147). Charcoal produced from pecan shells not only proves more effective for odor removal than commercial carbons used in water treatment, but also has comparable decolorizing power as charcoals made from oat hulls and com cobs (148). In addition, activated charcoal made by treating the pecan shell charcoal with concentrated hydrochloric acid, washing it free of acid, and heating it in an electric furnace for four hours at 800—1000°C in an atmosphere of carbon dioxide, has the same decolorizing effect on aqueous solutions of azo dyes as activated charcoal sold for water treatment. Much of the walnut shell charcoal is sold to poultry producers some is used as a filtrant for high grade vinegar.  [c.279]

See pages that mention the term Drilling hook : [c.40]    [c.55]    [c.755]    [c.310]    [c.289]   
Standard Handbook of Petroleum and Natural Gas Engineering Volume 1 (1996) -- [ c.530 ]