1) Wellsite workovers, drilling technicians and drillers must understand the structural principles and operating parameters of the drilling tool. Use drilling tools reasonably according to the requirements of the instruction manual.
2) Requirements for drilling fluid: The motor of the screw drilling tool is a positive displacement type, and the factor determining the performance of the drilling tool is the input flow rate of the motor and the pressure drop acting on both ends, not the type of drilling fluid. The physical and chemical properties of the drilling fluid generally do not affect the performance of the drilling tool except for individual damage to the life of the drilling tool. However, the various hard particles contained in the drilling fluid must be restricted, because it will accelerate the wear of the bearings and the stator motor and reduce the service life of the drilling tool. Therefore, the sand content in the mud must be controlled below 0.5%.
Mud viscosity and specific gravity have little effect on the drilling tool, but have a direct impact on the pressure of the entire system. If the pressure under the recommended displacement is greater than the rated pump pressure, the mud displacement must be reduced, or it is necessary to reduce the flow The pressure drop of the drill bit. Each type of drilling tool has its own input flow range. Only in this range can drilling tools have higher efficiency. Generally, the middle value of the input flow range should be taken as the best input flow value.
3) Mud pressure requirements:
When the drilling tool is suspended and the displacement remains the same, the mud pressure drop through the drilling tool is also unchanged. As the drilling pressure increases when the drill bit contacts the bottom hole, the mud circulation pressure increases and the pump pressure increases. The driller can use the following formula to control operating:
Drilling pump pressure = circulating pump pressure + drilling tool load pressure drop
The circulating pump pressure is the pump pressure when the drilling tool does not touch the bottom of the well, also called the off-bottom pump pressure. When the drilling tool increases the torque, the pump pressure will rise, and the reading of the pressure gauge is called the drilling pump pressure. The off-bottom pump pressure is not a constant, it changes with the well depth and the characteristics of the mud, but in actual operation, it is not necessary to measure the accuracy of the circulating pump pressure at any time. Generally, the off-bottom pump pressure after each contact is taken as an approximate value. This can fully meet the accuracy requirements of the formula.
When the drilling tool is working, when the drilling pump pressure reaches the maximum recommended pressure, the drilling tool produces the best torque. Continue to increase the WOB. When the maximum design pressure is exceeded, the motor may brake. At this time, the WOB should be reduced immediately to prevent internal damage to the drill tool.
The torque of the drilling tool is proportional to the pressure drop generated by the mud flowing through the motor, and the speed is proportional to the input displacement. When the displacement is constant, the torque increases while the speed remains basically unchanged, and the speed reduction of the drilling tool from no-load to full-load generally does not exceed about 10%.
Post time: Jul-27-2020