Rotary Drill Pipe

The working principle of the ​​​​Rotary Drill Pipe is as follows:

Drill bit revolution: The drill rig applies a certain axial pressure (drilling pressure) and rotary torque to the drill bit through the drill pipe, so that the drill bit rotates clockwise around the axis, which is called the revolution of the drill bit. The speed of the drill bit revolution is the rotation speed of the turntable or downhole power drilling tool. When the drill bit revolves, the cone rotates around the axis of the drill bit. The linear speeds of the rows of teeth on the cone are different around the axis of the drill bit, and the linear speed of the outer row of teeth is the largest.

Drill bit self-rotation: When the drill bit rotates, the counterclockwise rotation of the cone around its own axis from the bottom plane of the cone to the tip of the cone is called self-rotation. The rotation of the cone is the result of the reaction of the rock to the crushing action of the teeth. The factors affecting the self-rotation speed of the cone include the revolution speed, the drill bit structure, the tooth surface structure, the drilling parameters and the rock properties. Under normal circumstances, the self-rotation speed of the cone is faster than the revolution speed of the drill bit. The ratio of the self-rotation speed of the cone to the revolution speed of the drill bit is called the wheel head ratio, and the value of the wheel head ratio is generally between 1 and 1.5.

Crushing rocks: When the drill bit rotates into the rock formation, the teeth on the cone impact and press into the formation in turn. This action can crush part of the bottom rock, and at the same time, the shearing action brought by the sliding of the cone cuts off the other part of the rock remaining between the teeth, so that the bottom rock is completely crushed and the wellbore can be extended.

Drilling fluid flushing: The drilling fluid is injected into the Rotary Drill Pipe, and then enters the drill bit through the Rotary Drill Pipe to lubricate and cool the drill bit. The drilling fluid also has impact force, which can flush the broken rock particles and take them away from the bottom of the hole.

Longitudinal vibration (axial vibration): When the drill bit is working, for a cone, the contact between the teeth and the bottom of the well is alternating between single teeth and double teeth. When a single tooth touches the ground, the drill bit will produce axial vibration, which helps the teeth to crush rocks more effectively.