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Factors Affecting The Use Of Tapered Button Bits

Update:25-02-2021
Abstract:  Although tapered button bits are designed for wider drilling conditions, the following factors have a great influence ...

  Although tapered button bits are designed for wider drilling conditions, the following factors have a great influence on the normal operation of drill pipes.

  1. Drilling fluid

  The tapered button bits can be adapted to various types of drilling fluid, but the specific gravity and viscosity of the drilling fluid should be considered. Under the premise of satisfying well washing, the specific gravity and viscosity of drilling fluid should be reduced as much as possible, and the specific gravity of drilling fluid should not be greater than 1.50.

  2. Weight on bit

  In drilling operations, the weight of the drill bit should be gradually increased so that the pressure drop of the drill rod motor reaches the upper limit of the specified value as much as possible, to ensure that the drill rod motor provides the maximum output torque to meet the demand for rock-breaking drill bits. At the same time, the WOB should be controlled within the recommended maximum WOB. Excessive WOB will not only damage the thrust bearing of the driveshaft but also cause the motor pressure to drop to be too high and lagging. If the dead time is too long, the motor will be seriously damaged.

  3. Torque

  The characteristic of tapered button bits is that the output torque is proportional to the voltage drop of the motor. The actual output torque of the drill pipe during operation depends on the weight of the drill bit. Theoretically, the torque change does not affect the working speed. From no-load to the effective maximum working load area, the motor with better performance reduces the speed by no more than 10%, and the tapered button bits drive the drill bit to rotate clockwise, and at the same time generate a counteracting torque on the drill casing. The magnitude of reaction torque is the sum of output torque and friction loss torque. The reaction torque is transmitted to the drill string through the tapered button bits housing, which causes the upper part of the tapered button bits motor to be tightly connected, while the lower part of the tapered button bits motor releases the convex buckle. When the drill is stuck, the reaction torque reaches its maximum value. Since the reaction torque will affect the azimuth angle of the borehole, the existence of the reaction torque should be considered during directional operations.