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Performance requirements of through-cable drill pipe measured while drilling
Release time:
2021-12-16
Author:
Source:
The central cable drill pipe is the component with the most complex force and the worst working condition in the process of directional drilling. During the drilling process, the central cable drill pipe shall not only bear the pushing and pulling force exerted by the drilling rig and the counter torque of the screw drilling tool, but also serve as a medium channel to transport mud or other pressure medium to the bottom of the hole. At the same time, during the construction of near-horizontal long drilling and ultra-long drilling, drilling into the lower inclined hole or branch hole will produce additional bending stress, which can easily cause fatigue damage of the drill pipe. The central cable drill pipe is also the signal transmission device between the hole bottom inclinometer unit and the orifice inclinometer, which shall ensure real-time, safe and reduced signal transmission between the hole bottom inclinometer unit and the orifice inclinometer.
Through cabledrill pipeIt is a component with complex force and harsh working conditions in the process of directional drilling. During the drilling process, the central cable drill pipe must bear both the pushing and pulling forces exerted by the drilling rig.Screw drilling toolof the counter-torque,It is also used as a medium channel to transport mud or other pressure media to the bottom of the hole. At the same time, during the construction of near-horizontal long drilling and ultra-long drilling, drilling into the lower inclined hole or branch hole will produce additional bending stress, which can easily cause fatigue damage of the drill pipe. The central cable drill pipe is also the signal transmission device between the hole bottom inclinometer unit and the hole hole inclinometer. It should ensure real-time and safe signal transmission between the hole bottom inclinometer unit and the hole inclinometer, reduce the influence of complex force, vibration and pressure medium disturbance of the drill pipe on the signal transmission reliability during drilling, and ensure the accuracy and safety of directional drilling construction. It can be seen that the central cable drill pipe must have the characteristics of high strength and high signal transmission reliability.
Main technical parameters
Through the analysis of the working conditions of the central cable drill pipe, combined with the coal mine underground supporting equipment performance and use requirements, the main technical parameters of the central cable drill pipe:
① Drill pipe bodyΦ73mm, wall thickness 5.6mm, joint outer diameter 75mm;
② The length of the drill pipe is 3 m;
③The maximum tensile capacity of drill pipe is 800 kN; ④The maximum torsional capacity of drill pipe is 6 500 N · m;
⑤ The insulation resistance is greater than 10 MΩ; ⑥ The resistance of the central cable device is less than 0.5 Ω.
Overall structure design
The central cable drill pipe is divided into two parts: signal conduction device and drill pipe body. The drill pipe body is the carrier of other parts of the central cable drill pipe, and is also the primary condition to ensure directional drilling construction.safety of construction. The signal conduction device of the central cable drill pipe is composed of the central cable device, the insulation device and the supporting device.
The central cable device is composed of a male connector, a wire, a female connector and a reducing spring, and its function is to transmit a two-way communication signal between the bottom of the hole and the orifice device.
The insulation device is composed of a plastic male connector, a conduit and a plastic female connector. Its function is to isolate the central conduction device from mud or other pressure media, protect the communication safety of the central conduction device, and preventLoss of communication signals during conduction.
The supporting device is composed of a positioning retaining ring and a stabilizer. Its purpose is mainly to position the plastic male and female joints in the axial direction of the drill pipe, prevent the central conduction device and the insulation device from moving when the drill pipe is connected, and ensure the reliability of signal transmission. In addition, the stabilizer can reduce the disturbance of mud or other media to the pipeline, and avoid the conduction device and the drilling medium due to the fracture of the pipeline.
1) Structural design. In order to meet the needs of different construction processes, the main structure of the drill pipe is not much different from the structure of the ordinary geological drill pipe. The length of the drill pipe is 3 m to reduce the connection point of the drill pipe and shortenDrilling auxiliary time; pipe body usedΦ73mm, wall thickness 5.6mm high-strength seamless steel pipe, to reduce the quality of the drill pipe without affecting the strength of the drill pipe;
ConnectorΦ75 mm to improve the strength of the threaded part of the joint; the welding area of the inner hole of the drill pipe is machined to ensure a smooth transition between the joint and the rod body, so as to facilitate the installation and disassembly of the signal transmission cable and reduce the pipeline loss of liquid kinetic energy in the transmission process.
The central cable drill pipe is generally made of medium and low carbon chromium manganese molybdenum alloy structural steel with yield strength greater than 650 MPa and tensile strength greater than 800 MPa. In order to ensure the connection strength of the drill pipe, the male and female threaded joints of the drill pipe shall be made of better material than the drill pipe body. Considering comprehensively, it is required that the yield strength of the rod body is greater than 835 MPa, the tensile strength is greater than 980MPa, and the elongation is greater than 12%. The yield strength of the joint is greater than 925MPa, the tensile strength is greater than 1 070 MPa, and the elongation is greater than 14. 5%.
2) Drill pipe body thread design and check. The thread structure of the central cable drill pipe continues the conical trapezoidal thread structure of the ordinary rope coring drill pipe, which is characterized by increasing the cross-sectional area of the thread root, namely
The thread strength is increased; at the same time, the thread pitch is increased, that is, the contact area of the thread connection is increased, the centering accuracy and connection rigidity of the thread connection are improved, the thread force is uniform, the transmission torque is large, and the sealing performance is good. The tooth height is determined to be 1. 5mm, which is about 2 times of the tooth height of the general rope coring drill rod, which not only increases the thread strength, but also reduces the risk of drill rod tripping.
Key words:
Requirements, drill pipe, device, heart, thread, joint, signal, greater than, drilling, strength
