Abstract: This method comprises injecting a first primary plugging mass (4), mixed with a binder, having given composition and physico-chemical properties, and allowing this primary mass to thermically solidify; after a baking of this primary mass, drilling a hole (8) of a given length and thereby achieving a degassing, and injecting in this hole a second plugging mass, termed secondary mass, having suitable composition and physico-chemical properties which is mixed with a binder and is more fluid than the primary mass and has a hardening speed lower than the hardening speed of the primary mass, so that the secondary mass can diffuse into cracks in the primary mass before solidifying. The secondary mass reinforces the zones of the primary mass which have been rendered fragile by microcracking, and thereby again provides a suitable length of the tapping hole.