Subterranean barriers, methods, and apparatuses for forming, inspecting, selectively heating, and repairing same

A method of forming a subterranean baffler adjacent a selected region of a subterranean formation, comprising:

• placing a plurality of casing strings within a subterranean formation, each casing string of the plurality of casing strings comprising a bore extending longitudinally through at least a portion thereof, each of the plurality of casing strings being laterally adjacent to at least one other casing string of the plurality of casing strings;
• interlocking each casing string of the plurality of casing strings to at least one adjacent casing string through an interlocking structure extending between at least one casing string of the plurality of casing strings and at least another adjacent casing string of the plurality of casing strings;
• joining at least two laterally adjacent casing strings of the plurality of casing strings to one another by forming at least one weld substantially longitudinally along the interlocking structure formed between two adjacent casing strings;
• and
• disposing baffler filler material at least partially within the interlocking structure.