Patent ID: 8881845
Filing Date: 2014-11-11
Classification: E21B

Abstract:
1. A method of milling a window through a casing in a primary well bore and drilling a sidetracked well bore into a formation comprising: running a drilling assembly including a body having an axis defined therethrough and a track formed thereon, a piston that is movable within a cavity formed in the body, a stationary cutting structure coupled to the body, and a movable cutting structure coupled to the body, wherein the movable cutting structure is coupled to the piston via a link and is slidingly engaged with the track formed on the body and is movable along the track between a collapsed position and an expanded position; milling a window through the casing in a first trip into the primary well bore; drilling the sidetracked well bore in the first trip into the primary well bore; applying a differential pressure across a lower end of the piston; retracting the movable piston disposed in the cavity formed in the body of the drilling assembly from a downstream position to an upstream position; and moving the movable cutting structure along the track from the collapsed position to the expanded position via the link during the retracting of the movable piston.