METHOD AND APPARATUS FOR HYDRAULIC STEERING OF DOWNHOLE ROTARY DRILLING SYSTEMS

摘要

A method for hydraulically controlling the direction of a drill bit or bottom hole assembly containing a drill contains lateral orifices (40) which can be selectively opened and closed to move a portion of drilling fluid from the drill string out into a narrow gap between the lateral orifices and a lateral bore hole face or wall, which produces a lateral hydraulic force to thereby push the drill bit or bottom hole assembly in an opposite direction of the fluid flow through the lateral orifices. The apparatus for accomplishing this hydraulic steering can provide for the movement of the tip of the orifice into close proximity with the bore hole face to thereby increase the lateral hydraulic force created. This method can also be adapted to push- the -bit bore hole pads to minimize their contact with the bore hole while increasing the lateral force obtained by their engagement.