ONGC wanted to increase ROP, improve cost efficiency, and avoid bit damage and NPT while drilling through interbedded weathered and basaltic formations.
The challenging application caused premature impact damage to conventional roller cone and PDC bits in the offset well. Junk recovery runs increased NPT, and unstable bit and BHA configurations caused high shock and vibration, increasing drilling time and costs. Drilling the section to TD required nine to 15 roller cone bits at an average ROP of 0.5 to 1 m/h and an average meterage between 60 and 100 m.
Combined with two stabilizers in the BHA configuration, a new design of 16-mm hybrid AxeBlade bits with Stinger elements created for the application would improve stability compared to baseline configurations used in offset wells.
Using the hybrid AxeBlade bit enhanced with Stinger elements on an optimized rotary BHA, ONGC drilled 952 m at an average ROP of 1.9 m/h. A second bit drilled 960 m at an average ROP of 1.83 m/h. Both bits completed the 12¼-in section in the same formation that required 15 bit trips to drill in an offset well. ONGC met the objectives of the run, as the hybrid bit lowered the cost per meter of the section. The customer saved nearly 36 offshore rig days, improved ROP compared to the offset average, and achieved nine times improvement in meters per bit. The run resulted in a 40% reduction in cost per meter.
