Abstract: A back-off sub apparatus is disclosed. The apparatus includes a connection connecting a rotational section and a non-rotational section. The rotational section is designed to be rotated via a ball dropped into the well under sufficient pressure to cause the rotational section to rotate relative to the non-rotational section supplying a controlled and sufficient torque to the connection to break the connection. The connection then is unthreaded by normal surface action. The disconnected or upper section of the apparatus and the drill string section associated with it can be withdrawn from the well leaving the lower portion and the drill string section associated with it in the well.

Abstract: A drill bit for removing a surface subject to a subsurface pressure and an environmental surface pressure at least equal to the subsurface pressure, which comprises jetting fluid through a nozzle facing and located a predetermined distance from said surface, said nozzle being shaped to eject the fluid in a steam having a higher core pressure than said environmental pressure, said higher pressure stream having adjacent thereto at least one zone of pressure negative relative to said subsurface pressure, said distance being predetermined to expose said surface to said zone of negative pressure, whereby said surface is caused to explode into said zone of negative pressure from the force of said subsurface pressure.

Abstract: A method and abstract of removing a surface subject to a subsurface pressure and an environmental surface pressure at least equal to the subsurface pressure, which comprises jetting fluid through a nozzle facing and located a predetermined distance from said surface, said nozzle being shaped to eject the fluid in a steam having a higher core pressure than said environmental pressure, said higher pressure stream having adjacent thereto at least one zone of pressure negative relative to said subsurface pressure, said distance being predetermined to expose said surface to said zone of negative pressure, whereby said surface is caused to explode into said zone of negative pressure from the force of said subsurface pressure.