What is the effect of choosing a reasonable drill bit and rod size
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In the mining business, the large gap between the drill rod and the shaft wall is likely to cause severe vibration, especially in the vertical hole with weak resistance, which requires high rotation. The motor rotor has high inertia due to its high speed, and many systems are designed to be rigid and will not slow down when the required torque increases.
The drill rod system driven by the rotating table has a high rotational inertia, which greatly increases the cost and time. The traditional rotating table and drive system are used as a reflector for torsional vibration, which is used for longitudinal vibration, which is prone to failure. Side tracking in a long and thin hole is a very difficult operation, and many issues need to be considered.
The focus of the drilling strategy is to plan as low as possible. In the high level of vibration, it is difficult to see the peak torque on the drill bit surface, and the control of the weight on the drill bit is limited by string vibration. Small size drill bit bearings are small and relatively weak, have a short life, cannot withstand high weight or rotation speed, have low permeability, and lack flexibility. Only a few types of drill bit are available, reducing bit optimization. The drilling bit has a higher inner diameter, can be more flexible, and also has a high equivalent circulation density.
Many operations prefer to use bentonite as a tackifier and these slurries are often used to remove surface solids, which in turn leads to thick filter cakes and increases the possibility of differential adhesion. This results in a slow penetration rate caused by a low circulation rate and increases the possibility of bit sticking. The drill bit and the drill rod vibrate more, forming a bend under uncontrolled conditions.
These tools are used for workover operations and may not be available in all areas. In the planning process before drilling, the drilling specifications can be customized. For drilling in soft formations, scour sometimes occurs. Under these conditions, the problem tends to become more and more serious. It is necessary to choose a reasonable size drill bit and drill rod.
