Controllable downhole directional drilling tool

Abstract

A directional drilling tool permits the control of the angle of drilling of a drill bit through the repeated placement or removal of a ball within the mudstream. The ball activates a clutch mechanism within the directional drilling tool. The clutch mechanism, upon activiation, locks the exterior of the directional drilling sub to a fixed angular orientation. Simultaneously, there is activated a deflection mechanism to deflect a drive shaft which is normally fixed in an aligned straight position within the tube body, so as to shift the normally straight aligned shaft to a deflected position, causing the bit and the sub to angle for drilling at a controlled angle of offset from the vertical. The unit is aligned and located using wireline measuring equipment of known design. Since the sub may be controllably set in a straight line drilling or an angle drilling position, it may be left permanently in position in a drill string significantly reducing the requirement to trip out of the well bore during directional drilling and significantly increase the flexibility available to the driller to deflect the direction of drilling while drilling is in progress. There is further provided a mechanism for assisting in returning the tool to the straight aligned position for resumption of straight drilling. A second embodiment utilizes a deflection cam engaging the drive shaft directly to effect the deflection of the shaft.

Dependencies are inferred from the claim text.