A method, system and plug for providing a cross-sectional seal in a subterranean well

A method, system and plug for providing a cross-sectional seal (40´´) in a well (2) comprising a pipe body (4) and an annulus (6), the method comprising: (A) lowering a pipe expansion device (14, 20) into the pipe body (4) to a selected location; (B) with the pipe expansion device (14, 20), expanding a section (L) of the pipe body (4) until contact with a wellbore wall (8), thus forming an expanded pipe section (18) closing the annulus (6); (C) lowering a fusible solid material (40) into the expanded pipe section (18); (D) lowering a heating tool (32) into the expanded pipe section (18); (E) activating the heating tool (32) and melting the fusible solid material (40) and allowing a molten mass (40´) thereof to fill a cross-sectional portion of the expanded pipe section (18); and (F) deactivating the heating tool (32) and allowing the molten mass (40´) to solidify and form the cross-sectional seal (40´´). (Figure 9)