Necessary for directional well-screw drill tool
Screw drilling tool (PDM dri) is a kind of volume-type downhole power drilling tool powered by drilling fluid to convert the liquid pressure energy into mechanical energy. When the mud pumped by the mud pump flows through the bypass valve into the motor, a certain pressure difference is formed at the inlet and outlet of the motor, and the rotor is pushed to rotate around the axis of the stator, and the speed and torque are transmitted to the drill bit through the universal axis and transmission shaft, so as to realize drilling and operation.
constituent part
The screw drill is mainly composed of four major assembly: bypass valve, liquid motor, universal shaft and drive shaft. Screw motor is the main component of drilling tool. Many practical and theoretical analysis results show that if the motor is to work normally and effectively, the pressure drop of each motor can be no more than 0.8 Mpa, otherwise the motor will be lost. The speed decreases quickly, but in severe cases, it completely stops turning, and the motor is damaged.
A guide range of the motor is level 1, and the mud flow used on site should be within the recommended use range, otherwise it will affect the motor efficiency or even increase the wear. The performance parameters of screw motor are the main performance parameters of screw drill tool. The theoretical output torque of the motor is proportional to the pressure drop of the motor, and the output turn is proportional to the input mud flow. With the increase of the load, the turn of the drill decreases, so as long as the reading of the pressure gauge on the ground and the flow of the pump, the torque and speed of the drilling tool can be controlled and controlled.
Bypass valve part
The bypass valve is composed of valve body, valve sleeve, valve cartridge and other components, under the action of pressure, the valve core slides in the valve sleeve. The movement of the valve core changes the flow of the liquid, causing the bypass valve to bypass and close, in the process, the valve sleeve and the valve body are in the bypass state, make the mud bypasses the motor and when the mud flow and pressure reaches the standard set hole, close the bypass valve hole, and the mud flows through the motor and turns the pressure into mechanical energy.motor
The motor consists of a stator and a rotor. The stator is made by pressing a rubber liner on the inner wall of the steel pipe. Its inner hole is a spiral with certain geometric parameters, and the rotor is a screw with a hard layer. The rotor and the stator engage each other, and the conduction difference is used to form a helical sealing cavity to complete the energy conversion. The spiral of the motor rotor has a single head and a long head. The less the head of the rotor, the higher the speed, the less the torque; the more the head, the lower the speed, the greater the torque, the mud flow value is too small or stop the pump, the spring lifts the valve core, the bypass valve hole is in the open position- -in the bypass state.
cardan shaft
The function of the universal axis is to change the planetary movement of the motor into the fixed shaft rotation of the transmission shaft, transfer the torque and speed generated by the motor to the transmission shaft to the drill bit, the universal axis adopts flexible shaft type,
transmission shaft
The function of the drive shaft is to transfer the rotating power of the motor to the drill bit, while bearing the axial and radial load generated by the drill pressure. Therefore, the drive shaft cloud to be high hardness, wear resistance and service life. At this time, the quenching heat treatment can greatly improve the service life of the transmission shaft;