Drill bit for horizontal directional drilling of rock formations

摘要

The method includes the step of causing a specially-configured drill bit (102) at one end of a drill string (104) to intermittently rotate as it digs in, stops rotation until the rock fractures, and then moves after fracture in a random, orbital intermittent motion. Preferably the drill string (104) is rotated under pressure at a substantially constant rotational velocity at the other end of the drill string by a conventional directional drilling machine. A fluid (not shown) may be pumped into the drill string (104) and out the drill bit (102) to lubricate the hole and disperse cuttings. IMAGE