Tri-cone bits for horizontal and hard formation drilling applications

摘要

The present invention discloses a tri-cone drill bit comprising: three head sections with upper parts thereof jointed together to form a bit body, three cones rotatably mounted to lower ends of the head sections respectively, nozzle sockets designed on the bit body between respective head sections and each having a hole in which a nozzle is mounted, wherein gage cutters are mounted to an upper trailing side of each head O.D. surface to form a gage holding surface thereon, and a leading side of each head section is backwardly slanted as a whole. The design of gage surface at trailing sides of head sections increases the bit's stability, reduces lateral vibration and also reduces tendency of bit deflection in horizontal drilling applications and effective working life of the bit is improved. Backward slant of leading sides of head sections facilitates upward carrying of drilling cuttings and improves drilling efficiency. Jets from the nozzles are respectively directed to the leading side of each following cone, which enhances bottom hole cleaning and cooling of cutting elements and leads to a longer working life and higher ROP of the bit.