PDC bits, i.e., polycrystalline diamond composite bits, have been widely used in oil drilling because of their fast penetration rate, long life and high footage. Since 1973, when General Electric introduced PDC cutting blocks and developed the first PDC drill bit, this technology has received widespread attention. Today, almost all drill bit manufacturers have adopted PDC technology to produce their own series of PDC drill bits.
1) Structural characteristics of PDC drill bits
PDC drill bits are mainly composed of drill bit body, PDC cutting teeth and nozzles and other components, and the differences in its structure and manufacturing process are mainly divided into two series: steel body and carcass. The steel body PDC drill bit is made of medium carbon steel material and uses mechanical manufacturing process to fix the PDC cutting teeth on the crown of the drill bit by pressing into a tight fit. This type of drill is relatively simple to manufacture, but the drill body is susceptible to erosion and the cutting tooth fastness is not high, so it is relatively rarely used.
On the other hand, the upper part of the drill bit body of the carcass PDC drill bit is a steel body, and the lower part is made of tungsten carbide wear-resistant alloy carcass, which is formed by powder metallurgy sintering process. Its PDC cutting teeth are welded with the carcass with a reserved groove through low-temperature solder. This design of tungsten carbide carcass has high hardness and erosion resistance, so it significantly extends the life of the drill bit and improves the footage efficiency, and is now widely used in oil drilling.
2) The working principle of PDC drill bits
PDC drill bits mainly rely on cutting methods to break rock. Its self-sharpening teeth cut easily into the ground under the action of drilling pressure and shear the rock forward under the action of torque. Multiple PDC cutting teeth work at the same time, which increases the free surface of the rock at the bottom of the well, making the rock more easily broken under the action of shear, thereby improving the rock breaking efficiency and drilling speed.
3) Correct use of PDC drill bits
PDC bits are best used in homogeneous soft to medium-hard formations, avoiding gravel formations and soft-hard alternating formations. It is recommended to drill with low drilling pressure, high speed and large displacement to ensure optimal use. In addition, before the drill bit goes down, it should be ensured that the bottom of the well is clean and free of metal falling objects, and when the drill bit is just going down, small drilling pressure and low speed should be used to run and close, and then resume normal drilling operations after the bottom of the well is formed.
Grace Ma
Post time: Apr-18-2025
