Casing exit joint with easily milled, low density barrier

Abstract

A casing exit joint with an easily milled and low density barrier. A casing exit joint for use in drilling a lateral wellbore outwardly from a parent wellbore includes a generally tubular window structure having a window formed through a sidewall of the structure. An outer sleeve is disposed external to the window structure, so that the sleeve overlies the window. A hardenable substance supports the sleeve against deflection toward the window. A method of drilling a lateral wellbore extending outwardly from a parent wellbore includes the steps of: providing a casing exit joint including a hardenable substance positioned in a sidewall of the casing exit joint; then installing the casing exit joint in the parent wellbore; and then cutting through the hardenable substance in order to provide access for drilling the lateral wellbore.

Dependencies are inferred from the claim text.