Drilling Hole-Diameter

Klein and co-workers [76, 77] investigated catalysts made by combinatorial hydrothermal synthesis directly in the reactor vials. The reactor for the catalyst syntheses shown Figure 3.46 consists of a silicon base-plate fixed in a circular housing. To generate the 37 vials, a PTFE disk of 4 mm thickness with drilled holes (diameter -1.4 mm) is placed directly on the silicon base-plate and press-fitted by an addition stainless-steel plate [76],... 

The type of blasthole stoping technique presented in this case study mine varies according to stope sequence and ore zone width. For each type of stope, blasting design practices have been standardized in terms of drilled hole diameter, range of powder factor, and the type and pattern of the explosives used. 

Minimum Hole Diameter Calculation. The relationships between pin displacement, pin diameter, plate thickness, and drilled hole diameters are trigonometric. We calculate Eq. 38.1 ... 

The 45° transducer was used to inspect side drilled holes, with their centres located 40 mm below the surface. Due to the coarse material structure the echoes from the holes were totally masked by clutter. An example of an ultrasonic response signal, emanating from a hole with a diameter of 8 mm, is shown in the left part of Figure 3. Scanning the surface above the 8 mm and 10 mm holes resulted in the B-scan image shown in the upper part of Figure 4. 

The calibration in UTDefect is perfomed by a side-drilled hole or a flat-bottomed hole. The flat-bottomed hole is approximated by an open circular crack with the probe s beam axis going normally through its centre. This approximation should be sufficiently accurate as long as the crack diameter is larger than about a wavelength. 

In Lakestani (10) modelling work performed within the PISC III project is validated against experiments. Figure 1 shows the pulse echo response from the lower edge of a 10 mm vertical strip-like crack at centre depth 55 mm. The probe has the size 20 mm by 22 ram, is of SV type with angle 45 and has centre frequency 2.2 MHz and an assumed bandwidth of 2 MHz. The calibration is perfomed by a side-drilled hole of diameter 9.5 mm and centre depth 60 mm (the... 

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-... 

The second example shows results obtained with an angle beam probe for transverse waves in coarse grained grey cast iron. Two commercially available probes are compared the composite design SWK 60-2 and the standard design SWB 60-2. The reflector in this example is a side-drilled hole of 5 mm diameter. The A-scans displayed below in Fig. 5 and 6 show that the composite probe has a higher sensitivity by 12 dB and that the signal to noise ratio is improved by more than 6 dB. 

Side drilled holes are widely used as reference reflectors, especially when angle beam probes are used (e.g. for weld testing). However, the distance law of side drilled holes is different to that of a flat bottomed hole. In the literature [2] a conversion formula is given which allows to convert the diameter of a side drilled hole into the diameter of a flat bottomed hole and vice versa, valid in the far field only, and for diameters greater than 1.5 times the wave length. In practical application this formula can be used down to approximately one nearfield length, without making big mistakes. Fig. 2 shows curves recorded from real flat bottomed holes, and the uncorrected and corrected DGS curves. 

Normally, based on hole diameter, the designer can select drill collar diameter and drill pipe diameter. Next, specific pipe is chosen the maximum length of that pipe must be determined based on condition 1. For this purpose, the following equation is used ... 

Borehole depth 10,000 ft, deviated hole Drill pipe rotation rate 10 rpm Mud heat capacity 0.77 cal/g Hole diameter 12 in. 

Clearance Space between the outer diameter of the tool in question and the side of the drilled hole the difference in the diameter of the hole and the tool. 

Mixed metal hydroxide drilling muds have been successfully used in horizontal wells in tunneling under rivers, roads, and bays for drilling in fluids for drilling large-diameter holes with coiled tubing and to ream out cemented pipe. 

Anhedral pyrrhotite, from <10-200 pm in diameter, occurs in the matrix and in veins in all but one of the analysed samples. Visually the pyrrhotite appears to be inclusion-free, but Rare Pb- and Zr+REE-rich inclusions were found during analysis and it was noted that pyrrhotite in contact with pyrite generally has lower Co contents than other grains (3 ppm vs 280ppm, respectively, in samples from one drill hole) and have not been used for Interpretation. 

Spudding is the actual start of drilling a well and is akin to the first shovel of dirt at groundbreaking. A large bit, frequently from 18 to 38 inches (46-97 cm) in diameter, is used to drill a hole to a depth of from 10 to 100 feet (3-30 meters). The hole is then lined with a conductor pipe ( casing ). The space between the casing and the drilled hole (the borehole ) is filled with cement. 

On the debit side, the plugging tendency increases exponentially as hole diameters diminish. Smaller holes are also more prone to corrosion. While 5-mm (j -in) holes easily plug even by scale and rust, 13-mm (-ill) holes are quite robust and are therefore very common. The small holes are only used in clean, noncorrosive services. Holes smaller than 5 mm are usually avoided because they require drilling (larger holes are punched), which is much more expensive. For highly fouling services, 19- to 25-mm (f- to 1-in) holes are preferred. 

---