Sealing well casings

Abstract

An apparatus and method for sealing an inner wall of a portion of a casing positioned in a well employs an inflatable sleeve having an outer surface and a conformable composite sleeve of curable composition extending around the outer surface of the inflatable sleeve. The inflatable sleeve is inflated to compress the composite sleeve against the surface of the inner casing wall. A local, activatable energy source, positioned downhole to deliver heat to the composite sleeve, is activated to cure the composite sleeve to form a hardened sleeve. The hardened sleeve presses against the inner wall of the casing portion to create a fluid seal. The embodiments shown have a number of preferred features. The local energy source includes an exothermic heat energy source for generating heat energy to cure the composite sleeve. The composite sleeve includes a mixture of resin and a curing agent, and the exothermic heat source includes thermite. The thermite includes a composition having a metal oxide and a reductant. A starter mix is positioned adjacent the exothermic heat energy source, and the starter mix is ignited to start an exothermic reaction in the heat energy source. A conformable layer extends around the composite sleeve, with the layer serving to form a seal between the composite sleeve and the inner wall of the casing portion.

Dependencies are inferred from the claim text.