Deep Drilling Tools

In the majority of methods of drilling of small deep holes (many of them were elaborated by the engineers of General Electric), a tube through which an electrolyte is pumped under pressure serves as the tool. The tube can be made of metal (Fig. 20a) in this case, the tube itself is a cathode. It should be somewhat smaller in diameter than the required hole. The metal tube is coated externally (except for a tip area) with a film of insulation... 

Deep mixing is an in situ soil treatment which enhances the engineering properties of existing soil strata in well defined zones such as columns and panels. Virtually all soil deposits can be treated, except for those which contain rocks or boulders, or other debris which prohibit penetration by the drilling and mixing tools. Materials commonly mixed with the soil include cement, lime, flyash, and bentonite. Different equipment permits the additives to be placed as a slurry (wet), or as dry powders. Compared to the early work, currently achieved mixed-in-place piles are much larger, more uniform, and placed with much greater accuracy. 

The most complete and reliable data about the chemical composition of the Venusian surface comes from three Soviet missions, the Venera 13, Venera 14, and Vega 2 probes. These spacecraft actually reached the planet s surface and conducted studies of elements and compounds present on the planet s surface. In atypical experiment, one of the lander s tools would drill a hole into the planet s surface about 1.2 inches (3 cm) deep and extract a sample about 1 cm3 in volume. The chart on page 110 summarizes data obtained from these three missions and gives the composition of Earth s continental crust for purposes of comparison. Notice that the major differences in crustal composition between the two planets appears to be in the relative abundance of Si02 (45.6 percent on Venus compared with 60.2 percent on Earth) and of MgO (about 11.5 percent on Venus compared with 3.1 percent on Earth). Otherwise, the two planets do indeed appear to be almost "sister planets," at least with regard to the composition of their outer crusts. 

Formation pressure data were obtained from repeat formation tester (RFT) or modular dynamic tester (MDT) measurements of numerous deep wells in the Central North Sea. These data were used as the primary pressure dataset as they are the most accurate pressure measurements possible down-hole. The MDT/RFT wireline tool takes a pressure reading within a permeable formation, by setting a seal at a precise depth determined by using an accompanying gamma ray tool for depth correlation. Drill stem test (DST), mudweight data and kick (influxes of pore fluids into the wellbore) information was also used where RFT or MDT data were not available or of very poor quality. A summary of the various approaches used to derive formation pressures is provided by Holm (1998). 

Mix, A. C., W. Rugh, N. G. Pisias, S. Viers, T. Hagelberg, S. Hovan, A. E. S. Kemp, M. Leinen, M. Levitan C. Ravelo, 1992. Color reflectance spectroscopy a tool for the rapid characterization of deep-sea sediments. Proc. ODP, Init. Repts, 138. College Station, TX. (Ocean Drilling Program) 67-77. 

Example. The hole to be drilled is 3 in. deep. The machine and operator rate is 40/hr. The tool cost is 10 each. What is the production cost of the hole ... 

In mechanical deep hole drilUng processes with gun drills featuring a tool diameter smaller than d = 2 mm, challenges occur which are similar to the conditions in imcroniachining. The strictly limited tool rigidity of gun drills with small diameters restricts the adjustment of feed rates to just... 

Deep Hole Drilling with Small Diameters, Fig. 3 General tool design of single-lip gun drills (VDI3208)... 

Long shanked tools for deep hole drilling - challenges and Solutions). Dissertation, Universitat Stuttgart VDI-Richtlinie 3208-Entwurf (2009) Tiefbohren mit Einlippenbohrem (Deep hole drilling with gun drills). Beuth, Berlin... 

Zabel A, Heilmann M (2012) Deep hole drilling using tools with small diameters - process analysis and process design. CIRP Ann Manuf Technol 61 111-114... 

Easy - can be excavated by hand tools or light power equipment. Some large boulders may require drilling and blasting for their removal. Dewatering and bracing of deep excavation walls may be required... 

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