DEVICE FOR DRILLING CURVED BORE-HOLE Russian patent published in 1997 - IPC

FIELD: underground drilling of curved hole by rotary drill string. SUBSTANCE: device has curve guide unit, rotary drill bit, unit for creating unbalanced force and supporting unit. Curve guide unit can be connected with drill string with possible deviation of drill string in direction towards outer radius of curved borehole. Unit for creating unbalanced force which is preferably built by selected location of cutting members of drill bit can be rotated together with drill string for building up resulted unbalanced force acting along vector which is actually perpendicular to longitudinal axis of bit during drilling. Supporting unit can be rotated together with drill string and it is located in curve drilling unit close to cutting members of bit for possible crossing with plane of action of force created by longitudinal axis of bit and vector of resulted unbalanced force and with possibility of continuous contact with borehole wall during drilling. Supporting unit has smooth wear-resistant sliding surface. Curve guide unit has mandrel which is rotatable in body. Mountable on rear or front end of mandrel is ring for contacting with borehole wall and taking radial component of force created due to deviation of drill string at end of mandrel. Flexible can be connected to end of mandrel near contact ring for drilling curved boreholes of small curvature radius. EFFECT: high efficiency. 19 cl, 26 dwg