HIGH TORQUE PRESSURE SLEEVE FOR EASILY DRILLABLE CASING EXITPORTS

An apparatus for providing a high torque pressure sleeve for easily drillab le casing exit ports. A joint of tubular casing with a pre-formed window in the wall thereof has a tubular sleeve fixedly attached to the exterior of the tubular casing covering the window. The interior surface of the sleeve is sealed to the exterior of the tubular casing on opposite sides of the window. In use, the joint of the tubular casing is run down to the depth of interest in the earth wellbore and the window is oriented with respect to the formation of interest at the depth. The joint of tubular casing is then cemented in place, after which a whipstock is lowered into the wellbore, oriented and anchored therein. The assembly automatically fixes the axial and circumferential orientation of th e whipstock within a surrounding casing joint and holds the assembly in place. A drillin g assembly is lowered into the casing and a lateral bore is drilled off the whipstock through the window and the pressure sleeve and into the surrounding formation.