8.5 Inches

8.5 inch drill bits (215.9mm) are the workhorse of the oil and gas industry—this is the most common production hole size drilled worldwide. Whether you're running a 7" production casing string or completing a water well with 6" casing, the 8.5" bit handles the job. It's also the go-to size for geothermal drilling and large-diameter water well installations where flow capacity matters.

Core Advantages:

- Extensive range: PDC (4-8 blade), tricone TCI, and milled tooth configurations

- API 4-1/2 REG pin connection standard; optional 3-1/2 REG for lighter rigs

- Proven performance in shale, sandstone, limestone, and dolomite formations

- IADC codes available from 111 to 837 for complete formation coverage

- Hydraulic optimization for both water-based and oil-based mud systems

- Deep blade channels to prevent bit balling in sticky clay formations

Q: What's the expected ROP for an 8.5-inch PDC bit in shale?

A: In homogeneous shale at proper WOB (15,000-30,000 lbs) and 120+ RPM, an 8.5" PDC bit typically achieves 30-80 ft/hr. Harder or interbedded formations will reduce this rate significantly.

Planning a well with 8.5-inch hole sections? Send us your drilling parameters and formation data for a bit recommendation that maximizes your meters per bit run.