In the well drilling work, the drilling pressure problem will inevitably be encountered, which directly affects the drilling speed and the damage form of the drill bit, and also affects the progress of the whole project. Under normal circumstances, as the drilling depth of the small drilling machinery increases, the drilling The pressure will inevitably increase accordingly. As the drilling pressure increases, the drilling speed of small drilling machines will continue to increase, and the bearings and cutting teeth of the drill bit will accelerate the wear. This paper introduces the work in the small drilling machinery. Different impacts of drilling pressure on drilling in different construction stages.
There are three different stages in the relationship between the weight-on-bit and the drilling speed of a small drilling machine.
Volume crushing stage: When the drilling pressure is increased above the rock pressing hardness, the cutting teeth are cut into the rock to produce volumetric breakage, and the drilling effect can be obvious, which is normal drilling. Therefore, the weight of the bite applied to the roller bit must be such that the cutting teeth can be pressed into the rock to cause the rock to break.
Fatigue fracture stage: When the drilling pressure is close to the rock pressing hardness, although the cutting teeth are not cut into the rock, many cracks are generated on the rock surface, and the volume is broken by the repeated action of the cutting teeth;
Surface crushing stage: When the drilling pressure is less than the rock pressing hardness, the cutting teeth can not cut into the rock, and the rock can only be broken in the friction form on the rock surface, which has a large wear on the cutting teeth, although the drilling speed of the small drilling machine is also increased with the drilling pressure. Large and proportional increase, but the drilling speed of small drilling machines is very low.
Drilling pressure is a necessary condition for rock breaking at the bottom of the well. The size of the drilling pressure determines the way and characteristics of rock breaking. During the drilling, the drill bit is affected by the axial pressure and the rotating force. The cutting teeth are worn, dull or damaged during the process of pressing in and cutting the rock. Affect the drilling speed. By increasing the boring pressure, the test cone bit drilled into different grades of rock. The results show that different rockes have different drilling rig speeds for increasing the drilling pressure. Among them, medium-hard rock layers (rock grades 6-7) have a higher rate of drilling speed, while softer (rock grades 4-5) and harder (rock grades 8-9) are relatively The growth is not big. When drilling into cohesive soft rock, it is easy to produce water blocking paste, and the drilling pressure should be selected to be smaller.