Drilling Guidelines for Water Well Drill Pipes and Diamond Bits

In hard formations, water well drill pipe with diamond drill bits are the only effective option. Proper drilling techniques are essential to ensure efficiency, safety, and tool longevity.

1. Follow the “Five Prohibitions” and “Three Mandatory Lifts”

• Five Prohibitions: Do not use diamond bits to ream the hole, remove residual core, clear fallen core, clean collapsed fragments, or probe obstructions.
• Three Mandatory Lifts: Immediately pull out of the hole when:
  
  • • Resistance is encountered and light rotation is ineffective,
  • • Core blockage occurs,
  • • Penetration rate drops sharply.

2. Avoid Forcing the Bit
If the drill bit begins to slip, do not increase weight on bit or attempt forced drilling, and never allow dry drilling. Stop operations and pull out immediately to inspect.

3. Controlled Start-Up and Reduced-Load Drilling
Drill under reduced pressure. Straighten the drill string using a wire rope before adding rods. Then slightly lift the bit off the bottom using the hydraulic system before restarting, to avoid sudden rotation under heavy load that may damage the bit.

4. Do Not Add Rods Off Bottom
Before running in hole, ensure the proper remaining rod length is prepared. During a drilling run, do not lift the bit off bottom to add drill rods.

5. Maintain Circulation in Complex Formations
In unstable or complex formations, avoid rapid hoisting. Continuously pump drilling fluid to prevent borehole collapse caused by the swabbing effect.

6. Perform “Break-In” (Initial Grinding) for New Bits
A new diamond bit must undergo a proper break-in process to:

• Evaluate formation compatibility,
• Seat the cutting face against the bottom,
• Remove irregular edges and false sizing,
• Expose impregnated diamonds.

Break-in Procedure:
Start with light weight on bit (about one-third of normal), low rotary speed (approximately 100 rpm), and drill 0.2–0.3 m. Gradually increase to normal operating parameters. Keep the first run short and pull out in time to inspect the wear pattern of the bit.