High Penetration Rates and Extended Bit Life Through Revolutionary Hydraulic and Mechanical Design in PDC Drill Bit Development

Abstract

Summary PDC drill bit developments have been made to achieve higher penetration rates and longer life, involving a compromise between open, light set, bits for speed, and heavy set ones for durability. Developments are described which provided the benefits of both in a revolutionary hydraulic and mechanical design. The hydraulic design causes mud to flow first towards the bit center and then outwards. It was extensively flow tested using high-speed photography to ensure that bit balling was prevented. It includes features to address bit whirl which were demonstrated in full scale laboratory testing to reduce the bit's vibration level. The mechanical design maximizes open-face volume, known to benefit penetration rate, by using very high blades. However, the heights attainable can be limited by the bit body's mechanical strength. Steel was chosen to maximize blade strength and was coated with a newly developed hardfacing to improve erosion resistance. A program of fatigue testing assured adequate strength.