Directional cased hole side track method applying rotary closed loop system and casing mill

摘要

A bottomhole assembly (BHA) for single trip sidetracking operations has a mill for forming an open hole section in a cased wellbore and a steering unit for controlling drill bit orientation. During use, the drilling system is assembled at the surface and tripped into the wellbore. The mill is positioned adjacent a kick-off point and operated to form an open hole section. Thereafter, the drill bit is positioned adjacent the open hole section. An exemplary steering unit includes one or more force application members that, when energized, displace the drill bit such that the bit is pointed in a specified direction into the open hole section. The steering unit also includes one or more force application members that facilitate directional drilling through the open hole section. Other suitable steering units can employ devices that alter the BHA centerline geometry.