An apparatus and method for preparing a casing of a subterranean well and injecting a sealing mixture therein. The apparatus comprises an elongate body extending between top and bottom ends connectable to a wireline at the top and having a plurality of nozzles extending therethrough proximate to the bottom. A plurality of scrapers within the body each have a first retracted position and a second radially extended position engageable with the casing. A cavity is operable to contain the sealing mixture and a piston is movable therein so to eject the sealing mixture through the nozzles. The method comprises positioning the body in the well at a location to be sealed, extending the scrapers to engage with the casing, displacing the body so to scrape against the casing and retracting the scrapers. The piston is displaced so to eject the sealing mixture through the nozzles.