Systems and methods for removing and replacing a first sealant in a subterranean well include a running sub located at an end of a running string. A helical guide port extends through the running sub. A port exit of the guide port is at a downhole end of the guide port and extends through a sidewall of the running sub. An inner assembly is extendable through the guide port. A head assembly is located at a drilling end of the inner assembly. The head assembly is sized to pass through the port exit and is oriented to drill a helical path within the first sealant radially exterior of the inner casing and form a void.