Shaped charge assembly, explosive units, and methods for selectively expanding wall of a tubular

1. A method of reducing a leak in a sealant in an annulus adjacent an outer surface of a tubular in a wellbore, the sealant comprising voids and/or open channels, the method comprising:

inserting a plug into the tubular;

positioning an expansion tool within the tubular at a location uphole of the plug, wherein the expansion tool contains an amount of explosive material based at least in part on a hydrostatic pressure bearing on a wall of the tubular so that the amount of explosive material produces an explosive force sufficient to expand, without puncturing, the wall of the tubular and to compress the voids and/or collapse the open channels in the sealant; and

actuating the expansion tool to expand the wall of the tubular radially outward, without perforating or cutting through the wall of the tubular, to form a protrusion that extends into the annulus adjacent the outer surface of the wall of the tubular, wherein the protrusion seals the leak in the sealant by compressing the voids and/or collapsing the open channels in the sealant.

2. The method according to claim 1 , further comprising:

actuating one or more puncher charges of a puncher charge tool in the tubular to punch holes in the wall of the tubular at a location uphole of the plug; and

providing additional sealant into the annulus through the holes in the wall of the tubular.

3. A method of selectively expanding walls of two concentric tubulars comprising an inner tubular and an outer tubular, wherein a sealant comprising a porosity is provided in an annulus between the two concentric tubulars, the method comprising:

positioning an expansion tool within the inner tubular, wherein the expansion tool contains an amount of explosive material based at least in part on a hydrostatic pressure bearing on at least the inner tubular and the outer tubular so that the amount of explosive material produces an explosive force sufficient to expand, without puncturing, a wall of the inner tubular and a wall of the outer tubular and to reduce the porosity of the sealant; and

actuating the expansion tool once to expand both the wall of the inner tubular and the wall of the outer tubular radially outward, without perforating or cutting through the wall of the inner tubular and the wall of the outer tubular, to form a protrusion of the wall of the inner tubular that extends into an annulus between the inner tubular and the outer tubular and reduces the porosity of the sealant, and to form a concentric protrusion of the wall of the outer tubular into an annulus adjacent the outer surface of the wall of the outer tubular.