Buried drilling and hole collapse are the most common and troublesome problems in many complicated geological drilling construction projects. It is difficult to guarantee the quality and efficiency of drilling by conventional drilling technology.
However, the appearance of the following pipe perfectly solves this problem. It protects the borehole wall with the casing while drilling efficiently, and restrishes the borehole bending with the rigid guiding effect of the casing. At present, eccentric and concentric pipe drilling tools are widely used in China. Due to the thicker wall of the outer bit, the impact power transmission effect of concentric drilling tool is not as good as that of eccentric drilling tool for the same aperture construction. Only when the diameter of drilling tool is larger and the impactor with high wind pressure is selected, the effect is better, but the manufacturing cost is much higher than that of eccentric drilling tool. Eccentric pipe drilling tool not only has large hole diameter, but also has simple structure, low manufacturing cost and easy to use, so it has been widely used.
The working principle of eccentric bit is:
1, the DTH hammer eccentric with pipe drilling system, whatever the eccentric with pipe drilling tools are with tube when the drill drilling drilled by eccentric is greater than the casing diameter hole, and when drilling to the predetermined ground, convergence, and pipe drilling tools can be made with the largest outer diameter of the pipe drilling tool less than the inner diameter of tube boots, casing, to remove with pipe drilling tools, casing may remain in formation protecting hole wall.
2. When drilling normally, the compressed air provided by the air compressor enters the DTH impactor through the drill and drill pipe to make it work. The piston of the impactor impacts the normalizer of the drilling tool with the tube, and the normalizer transmits the shock wave and bit pressure to the eccentric bit and the central bit to break the rock at the bottom of the hole.
3. When the gravity of the casing is greater than the friction resistance of the formation to the casing wall, the casing will follow up with its own weight.
4. The hole drilled by the eccentric bit is larger than the maximum outer diameter of the casing, so that the casing is not hindered by the rock at the bottom of the hole and follows up.
Post time: Jan-04-2022