Patent ID: 8978782
Filing Date: 2015-03-17
Classification: E21B

Abstract:
1. A rotary drilling assembly for drilling a borehole penetrating a geological formation, the drilling assembly comprising: a drill bit positioned on a forward end of the drilling assembly to rotatably engage the formation; a bias unit coupled to the drill bit and configured to control a direction of drilling by the drill bit, wherein the bias unit comprises a tool body; a pad having a leading edge and a trailing edge, the pad being pivotally affixed to the tool body at the leading edge; and a linear actuator formed in the tool body and comprising a linear spring and a push rod, wherein the linear spring and the push rod are configured to engage and apply a linear force to the trailing edge of the pad that urges the pad radially outward from the tool body to contact a wall of the borehole during rotation of the drilling assembly, wherein the linear force applied to the trailing edge of the pad is substantially parallel to a longitudinal axis of the linear spring.