Tool for drilling curved sections of well holes

摘要

A drilling tool for deep wells having a motor-driven drill bit which can be turned at an angle to the axis of the primary well hole to produce lateral holes branching from the primary hole. The bit is rotatably-mounted in the last in a series of pivotally articulated links at the downhole end of the drill pipe string. The deviation of the drill bit from the well axis is controlled by pivoting the last link with respect to the penultimate link. The last link includes a sliding surface which bears against the wall of the well hole to effect the pivoting. In another form of the invention a spring effects the pivoting. Preferably stops are provided between the last and penultimate link to limit the angle of pivoting.