DOWNHOLE ADJUSTABLE BENT MOTOR

A bent sub for use in a bottom hole assembly, between the power section of a mud motor and the drill bit, which can have its bend angle altered from the surface while remaining downhole, and a method for adjusting the bend of a bent sub. A biasing mechanism includes a number of linear actuators radially positioned about the tool centerline and oriented for axial motion. The linear actuators are connected to travelling blocks, which engage the upper end of the inner race a pivoting bearing assembly. The lower end of the inner race is connected to the mud motor bearing assembly. The linear actuators and can be actuated in coordination to tilt the inner race, and hence, the mud motor bearing assembly, to various selectable angles in any radial direction for control of tool face. In an embodiment, the actuators are battery-powered motor-driven lead screws.