Average service life of 750 m/bit in f=6-10 roof sandstone mixed with coal gangue and mudstone

This case comes from a vertical-shaft high-level roof borehole project. The 120 flat-top four-wing drill bit was used in roof sandstone mixed with coal gangue and mudstone on a VLD-1000 directional kilometer drilling rig, completing 7,500 m of total drilling with an average service life of 750 m per bit.

Working Conditions

Formation and Drilling Parameters

Performance After Field Use

• Long service life: The bit achieved an average life of 750 m/bit in f=6-10 mixed formations, supporting long-distance continuous drilling.
• Stable structural integrity: After field use, the bit body, four-wing profile, and threaded connection area remained stable and reliable.
• Firmly bonded PDC cutters: The PDC cutters remained tightly bonded to the bit body, with no obvious loosening, detachment, or delamination.
• Outstanding wear and impact resistance: In alternating sandstone, coal gangue, and mudstone conditions, cutting-area wear remained controlled and predictable.
• Efficient cuttings removal: The flat-top four-wing structure supports efficient rock breaking and stable cuttings discharge, reducing the risk of sticking or bit balling.
• Solves a key field challenge: It helps improve drilling efficiency and service life in coal seam roof high-level borehole operations.

Image Captions

Before Use	After Field Use
Unused 120 flat-top four-wing drill bit, showing the complete cutting structure, PDC cutter layout, cuttings channels, and threaded connection area.	Our product after drilling in f=6-10 roof sandstone mixed with coal gangue and mudstone, showing firmly bonded PDC cutters, stable bit body, and controlled wear for long-hole drilling.

Key Advantages

• Extended wear life: Average service life of 750 m/bit for underground roof borehole and directional long-hole drilling.
• PDC cutter advantage: High-hardness PDC cutters offer strong wear resistance and remain firmly bonded to the bit body, reducing cutter-loss and abnormal failure risks.
• High-efficiency rock breaking: The four-wing flat-top design provides stable cutting coverage and balanced bottom-hole loading.
• Wide formation adaptability: Suitable for roof sandstone, coal gangue, mudstone, and f=6-10 medium-hard to hard mixed formations.
• Reliable drilling continuity: Stable water-cooled performance helps reduce bit replacement frequency and downtime.

Summary

In f=6-10 roof sandstone mixed with coal gangue and mudstone, our 120 flat-top four-wing drill bit completed 7,500 m of total drilling with an average service life of 750 m/bit, demonstrating high-efficiency drilling, extended wear life, and firmly bonded PDC cutter performance.