METHOD AND APPARATUS FOR A COMBINED EXIT GUIDE AND SECTIONAL MILL FOR SIDETRACKING

摘要

A casing mill (82) is positioned below a whipstock (80) or other exit guide in a drill string assembly used to mill a section of steel casing below the whipstock (80) and which as the section mill (82) moves down and mills along the section of casing, causes the whipstock (80) to be lowered down adjacent the milled-out casing and allows the drill bit and drill string to be run along the surface of the whipstock (80) and into the earth formation. In an altemative embodiment, the combination of having the section mill (82) below the whipstock (80) is used in open hole operations having no casing.