Method of and apparatus for releasing stuck pipe

Claim 1

IN APPARATUS FOR RELEASING A PIPE STRING STUCK IN A WELL BORE THE COMBINATION WITH MEANS FORMING AN INTERNAL SEAT IN THE STRING THROUGH WHICH FLUID MAY FLOW DOWNWARDLY THROUGH THE STRING THROUGH WHICH FLUID MAY FLOW POSED ION THE STRIONG FOR MOVEMENT INTO AND OUT OF CLOSING RELATION TO THE SEAT, OF MEANS ADAPTED TO BE LOWERED INTO THE STRING AND SHAPED FOR COACTION WITH SAID SEAT FORMING MEANS AND SAID MOVABLE MEANS TO LOCK SAID MOVABLE MEANS OUT OF CLOSING RELATION TO THE SEAT.

Claim 2

THE METHOD OF RELEASING A PIPE STRINK STUCK IN A WELL BORE, WHICH STRING IS PROVIDED WITH AN INSIDE SEAT THROUGH WHICH FLUID IS CIRCULATED DOWNWARDLY THROUGH THE STRING AND UPWARDLY IN THE BORE ABOUT THE EXTERIOR OF THE STRING, A VALVE ASSEMBLY MOVABLY DISPOSED IN THE STRING AND INCLUDING A HOUSING SHAPED FOR ENGAGEMENT WITH SAID INSIDE SEAT AND HAVING A PASSAGEWAY THERETHROUGH AND FORMED WITH A VALVE SEAT IN THE PASSAGEWAY THROUGH WHICH FLUID MAY FLOW THROUGH THE STRING, A VALVE MOVABLY DISPOSED IN THE HOUSING FOR MOVEMENT INTO AND OUT OF CLOSING ENGAGEMENT WITH THE VALVE SEAT AND YIELDABLE MEANS POSITIONED FOR COACTION WITH THE STRING AND SAID VALVE TO YIELDINGLY RESIST CLOSING MOVEMENT OF THE VALVE, WHICH METHOD COMPRISES INCREASING THE PRESSURE OF THE FLUID IN THE STRING TO CAUSE THE VALVE TO CLOSE AGAINST THE RESISTANCE OF SAID YIELDABLE MEANS TO CAUSE THE FLUID IN THE STRING ABOVE THE SEAT TO EXERT A DOWNWARD FORCE ON THE STRING AND THEREAFTER REDUCING THE PRESSURE OF THE FLUID IN THE STRING ABOVE SAID SEAT TO ALLOW THE VALVE TO OPEN.