Structural characteristics
- It consists of drill bit body, PDC cutting teeth and nozzle.
- According to the structure, it can be divided into two series: steel body and carcass. This structure significantly improves the wear resistance and service life of the drill bits.
- No moving parts, simple overall structure.
- It consists of drill body, scraper blade, distributor cap and nozzle.
- The scraper blade is welded to the bit body, usually made of tungsten carbide.
- Simple structure, low processing requirements.
Principle of operation
PDC drill bit
Breaking rock by cutting action, PDC cutting teeth cut into the formation under drilling pressure and shear the rock under torque.
- It is suitable for continuous and uniform stratum with high drilling efficiency.
drag Drill Bit
Breaking rock by cutting, the blade eats into the formation under drilling pressure and causes plastic flow or shear breakage of rock by torsion force.
- It performs well in soft and plastic formations, but is less efficient in hard formations.
Applicable formations
PDC drill bit
Suitable for soft to medium-hard formations, especially performs best in homogeneous formations.
- Not suitable for gravelly formations and hard-soft formations.
drag Drill Bit
Mainly used in soft and cohesive formations such as mudstone and shale.
- In hard formations they are inefficient and prone to wear.
Performance characteristics
- PDC drill bit:
- High abrasion resistance, strong impact resistance, long service life.
- Fast drilling speed, suitable for high speed drilling.
- No moving parts, high reliability.
- drag Drill Bit:
- Simple structure, low cost, easy to process.
- High drilling speed in soft formations, but fast wear, easy to form cone-shaped wear.
- Requires high volume drilling to clean the bottom of the well and cool the bit.
Recommendations for use
- Suitable for large sections of homogeneous stratum, low drilling pressure, high rotation speed and large displacement drilling are recommended.
- The bottom of the well should be cleaned before the drill bit is lowered into the well to avoid metal fallout.
- drag Drill Bit:
- Suitable for soft formations. It is necessary to control the drilling pressure and rotating speed to prevent the cutter flank from breaking.
- Pay attention to anti-slope and prevent well diameter reduction when drilling.
PDC and scraper bits have their own advantages, and should be matched according to the specific formation conditions and drilling requirements. PDC bits are more suitable for hard formations and high drilling efficiency, while scraper bits perform better in soft formations.
