The drill bit that makes the cutting edge is called a diamond core bit. The drill bit is an integrated drill bit. The entire drill bit has no moving parts. The structure is relatively simple, with high strength, high wear resistance and impact resistance. It is one of the three new technologies in the world in the 1980s.

This article contains the following:

What is a diamond core bit?

Diamond is the rock breaking mechanism of the drill bit

Diamond core bit classification

1.What is a diamond core bit?

The quality of the drill bit and whether the bit type is compatible with the lithology of the formation play an important role in accelerating the drilling speed and increasing the footage of a single bit. When drilling an oil and gas well, multiple drill bits of different sizes are generally used. When drilling the upper stratum, a drill bit with a larger diameter is used. Because the drill bit drills into a softer formation, a single drill bit has more footage and a shorter time. Several wells can be used repeatedly; while drilling a lower formation, a drill bit with a smaller diameter should be used. Because the formation is hard and the footage of a single drill bit is small, multiple drill bits are generally used. The drilling footage of a new drill bit depends mainly on the drill bit size, type, formation hardness and drilling parameters. In general, the smaller the drill bit size and the harder the formation, the less the footage; the larger the drill bit size and the softer the formation, the more the drill footage.

2.Diamond is the rock breaking mechanism of the drill bit

The rock breaking effect of the diamond core bit is completed by diamond particles. To know the rock breaking effect of the drill bit, we must understand the rock breaking effect of single diamond. In hard formations, single-grain diamond puts the rock under extremely high stress state (about 4200-5700MPa, some data think it can be up to 6300MPa) under the effect of drilling weight, which causes the rock to undergo lithological transformation from brittleness to plasticity. The single-grain diamonds are eaten into the formation, and the rock is cut under the action of torque. The cutting depth is basically equal to the depth of the diamond particles. This process is like "plowing the ground" so it is called the plow cutting effect of the diamond core bit.

In some brittle rocks (such as sandstone, limestone, etc.), the diamond particles on the bit under the effect of the weight-on-bit torque, the volume of broken rock is much larger than the volume of diamond particles eaten and rotated. When the pressure is not large, only small grooves can be formed along the direction of movement of the diamond. Increasing the pressure will break the deep groove of the small groove and the rocks on both sides, exceeding the cross-sectional size of the diamond particles.

The rock-breaking effect of the diamond bit is related to lithology and external factors (such as pressure, temperature, formation fluid properties, etc.) that affect lithology, and the weight of bit weight is an important influencing factor. Like rock cone bit, it has three methods of surface breaking, fatigue breaking and volume breaking when rock breaking. Only when the diamond particles have enough specific pressure to feed into the formation rock, and the volume of the rock is broken, can the ideal rock breaking effect be achieved.

3.Diamond core bit classification

diamond core bits are classified according to the inlay method of the cutting material. The inlay method refers to the distribution of diamond on the surface or inside of the drill carcass. According to this classification method, it can be divided into impregnated diamond core bits, surface mounted diamond core bits and inlaid diamond core bits.

diamond core bits are classified according to cutting materials as diamond core bits for drilling. There are many kinds of cutting materials, mainly including artificial diamond core bits, natural diamond core bits, diamond polycrystalline drill bits, diamond composite drill bits, single crystal and polycrystalline Drill bits, in-block diamond core bits and other new material drill bits.