Patent ID: 6978848

Claim:
Apparatus for penetrating a cavern at a lower end of a well bore in a subsurface formation wherein the diameter of the cavern is greater than that of the well bore, said apparatus comprising: means for penetrating said cavern, said means including an elongated projectile assembly having a projectile member disposed in said assembly and an explosive charge behind said projectile member, said projectile assembly being of a length greater than the diameter of said well bore but less than the diameter of said cavern; a suspension member including means for advancing said suspension member through said well bore, said projectile assembly pivotally mounted externally of said suspension member for extension alongside said suspension member; means for pivoting said projectile assembly between a first position extending substantially parallel to a longitudinal axis of the well bore and a second position substantially perpendicular to the longitudinal axis of the well bore; and means for detonating said explosive charge whereby to discharge said projectile member into a wall of said cavern.