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Drilling tool (also called downhole drill string) is the general term for drilling tools from the drilling faucet to the drill bit. It is mainly composed of a square drill pipe (or hexagonal drill pipe), a number of circular drill pipes, weighted drill pipes, drill collars, stabilizers, shock absorbers and a series of matching joints.
The drill pipe of drilling tools is the basic part of the downhole drill string. A drill pipe is like a circular hollow steel string. These drill pipes are connected to the position below the square drill pipe and above the drill collar. The main function is to transmit torque and transport drilling fluid, and use the method of continuously connecting drill pipes to achieve the purpose of deepening the borehole.
Below the drill pipe is a weighted drill pipe. The weighted drill pipe is similar to an oil well drill pipe and is also a hollow steel string drilling tool. The weighted drill pipe is connected between the drill pipe and the drill collar to prevent fatigue failure due to variation of drilling tool section. It can also replace part of the drill collar, but it is convenient for tripping and thus saves time.
The drill collar is located below the drill pipe and above the drill bit, and is also hollow. Its function is to provide the drill bit with pressure when drilling, and at the same time make the lower assembly of the drilling tool have great rigidity, and maintain the stability of bottom drill bit when it is working, which is good for preventing and overcoming drilling deviation.
In addition, there are stabilizers, shock absorbers, jars, borehole expanders and various matching joints in the drilling tools to meet the needs of drilling operations.
