Preparatory work before the use of a bit:
First of all, we should carefully check the use of the previous bit, understand the wear state of the drill diameter, check whether there is a loss of damage on the bit body (the missing part, such as the tooth drop, will cause damage to the drilling bit that is coming to the well).
The working stability of the bit plays an important role in preventing the well deviation and maximizing the performance of the bit. Therefore, the drill is recommended to drill in a stable working state when PDC bit is used. However, due to the specific drilling process and the particularity of borehole conditions, it is not necessary to pursue this stability at times. All stabilizers and reamers should check their outer diameter to ensure that the outer diameter is large.
The new drill is first drilling:
1. when the drill is near the bottom of the well, the pump will be discharged to the maximum and then start up, and the speed will be controlled at 30 ~ 60rpm. Slow down until the drill is in contact with the bottom of the well.
2. in order to form a new well bottom, drilling pressure should be applied in accordance with the recommended initial drilling pressure during drilling of the original 1m deep hole. The starting bit pressure of various sizes of drill bits of different sizes is provided in the table. The initial working parameters of drill bit (bit pressure and speed) should at least maintain the length of a drill bit.
3. after the new bottom hole is formed, the drilling pressure can be increased evenly and evenly until drilling pressure is reached. For extremely soft strata, the drilling pressure is very close to the initial drilling pressure. For hard formations, the formation of new bottom hole will take longer time and the final normal drilling pressure will be higher. The best drill pressure should be: when the drill pressure reaches this value, the bit's mechanical drilling speed ROP no longer increases with the new increase of the drill pressure, or the bit torque has reached the limit torque value.
In addition to not running in the process of forming new bottomhole, follow the same rules as the first drill for new drill.
1. when drilling the end of the drill pipe, reduce the speed to 30 ~ 60rpm.
2. brake brakes, no more drilling, so that part of the drill bit pressure can be released in a few minutes.
3. remove the bit from the bottom of the well and stop the bit rotation.
4. after the single root is finished, the bit is re entered into the well. When the drill bit is near the bottom of the well, the drilling pump discharge is fully opened, so that the bottom hole mud is fully circulated. Open (or top drive), speed 30 ~ 60rpm.
5. when the drill reaches the bottom of the well, increase the bit pressure first and then increase the speed.
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