Powder drilling

The chemical compositions of the ancient Egyptian Blue samples (reported in the following section) were determined by atomic absorption spectrophotometry using the hydrofluoric acid digestion method together with the lithium metaborate fusion method for the silica determination (9). Some 20-30 mg of powder drilled from the objects was used for these analyses. Additionally, the arsenic concentrations were determined by x-ray fluorescence spectrometry. The precision of the analytical data was 1-2% for the major elements (>10% concentration) and deteriorated to 5-20% for the trace elements (<0.1% concentrations). However, due to the inhomogeneity of the material, variations in elemental concentrations (i.e., major, minor, and trace) of 10-15% can be expected within a single object. 

Chloride profile based on cores or powder drilling. The location of the cores to be taken should be based on a problem-oriented approach, e. g. on a half-cell potential map. For cores dry drilling is preferable, in any case excess of water should be avoided due to the risk of washing out chlorides. The cores shall be identified and stored in plastic bags until analysis in the laboratory. 

The location of powder drilling should be determined as for cores. Three to five 20 mm diameter holes should be drilled to the required depth (e. g. in steps of... 

Abrasive appHcations for industrial diamonds include thek use in rock drilling, as tools for dressing and tmeing abrasive wheels, in polishing and cutting operations (as a loose powder), and as abrasive grits in bonded wheels and coated abrasive products. 

Density. The density of the drilling fluid is adjusted using powdered high density soHds or dissolved salts to provide a hydrostatic pressure against exposed formations in excess of the pressure of the formation fluids. In addition, the hydrostatic pressure of the mud column prevents coUapse of weak formations into the borehole. Fluid densities may range from that of air to >2500 kg/m (20.8 Ib/gal). Most drilling fluids have densities >1000 kg/m (8.33 lb/gal), the density of water. The hydrostatic pressure imposed by a column of drilling fluid is expressed as follows ... 

Low molecular weight (1000—5000) polyacrylates and copolymers of acryflc acid and AMPS are used as dispersants for weighted water-base muds (64). These materials, 40—50% of which is the active polymer, are usually provided in a Hquid form. They are particularly useful where high temperatures are encountered or in muds, which derive most of their viscosity from fine drill soHds, and polymers such as xanthan gum and polyacrylamide. Another high temperature polymer, a sulfonated styrene maleic—anhydride copolymer, is provided in powdered form (65,66). AH of these materials are used in relatively low (ca 0.2—0.7 kg/m (0.5—2 lb /bbl)) concentrations in the mud. 

Carburization By Fusion. This method is used for the preparation of tungsten carbide for the mineral industry, ie, for coarse-grained powder or castings for welding (qv) onto oil drills and wear-resistant parts. 

Quality Control. The spectrometer is the most suitable instmment for determining most low level residual impurities. ASTM E414 is the standard method for the measurement of impurities in copper by the briquette dc-arc technique (65). In this method, the sample in the form of chips, drillings, or powder is briquetted and excited in a d-c arc opposite a high purity copper rod. Impurities in the ranges noted can be measured ... 

The calculations lor recommended makeup torque assume the use ol a thread compound containing 40% to 60% by weight of linety powdered metallic zinc, or 60% by weight of finely powdered metallic lead, applied thoroughly to all threads and shoulders the use of the modified jackscrew formula as shown in the lAOC Drilling Manual and the API Spec RP 7G (latest addition) and a unit stress of 62,500 psi in the box or whichever is weaker. 

A plugging slurry for oil and gas well drilling is given in Table 18-7 [1441]. It is formed by adding water to the Portland cement suspension containing the other three constituents. The bentonite clay powder is premixed with water... 

Figure 14.10 illustrates the method of seismic prospecting on land by what is known as reflection shooting. A hole usually 10 to 12 cm in diameter is drilled to a depth of 15 to 30 m. The charge of explosive is likely to be 5 to 12-5 kg and the stemming used is usually water. As the explosive must fire under a depth of water which may exceed 45 m, special varieties of gelatines are employed (see p. 53). Alternatively, a powder explosive can be sealed into pressure-resistant metal containers. Special detonators are also employed, not only to withstand the possible head of water, but also to have a specially short bursting time (see p. 113). 

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