Patent ID: 8505621

Claim:
A casing string capable of being disposed in a bore, the casing string having a central longitudinal axis and comprising: a first portion in an inner wall, the first portion having a smaller cross-sectional thickness than at least one other portion of the casing string; and a second portion in part of a circumferential portion of an outer wall of the casing string, the second portion having a smaller cross-sectional thickness than a portion of the casing string located opposite to the second portion in a cross section that is perpendicular to the central longitudinal axis of the casing string, wherein the second portion comprises a plurality of openings in which a plurality of plugs are positioned, the plurality of plugs being made from a different material than a material from which the second portion is made, wherein the casing string is capable of providing a pressure seal between an inner region defined by the casing string and an environment exterior to the casing string until at least part of the second portion is drilled or milled, and wherein the second portion is capable of providing a channel for a cutting tool to traverse toward a formation adjacent to the casing string.