Cementing tool

Claim 1

A FORMATION PACKER SHOE COMPRISING: A MANDREL, MEANS FOR ATTACHING THE MANDREL TO A CASING STRING, A VALVE BODY MOUNTED WITHIN THE MANDREL HAVING A PORT AND AN ORIFICE THEREABOVE, VALVE MEANS IN THE VALVE BODY ADJACENT THE PORT, MEANS BIASING THE VALVE MEANS INTO CLOSING POSITION ACROSS THE PORT, OBSTRUCTION MEANS IN THE PORT HAVING A CONDUIT THERETHROUGH AND PREVENTING CLOSURE OF THE VALVE MEANS, AN EXPANDABLE PACKER MOUNTED ON THE MANDREL, MEANS ON THE MANDREL FOR EXPANDING THE PACKER, MEANS CONNECTING THE VALVE BODY AND EXPANDING MEANS FOR AXIAL MOVEMENT THEREBY, FRANGIBLE MEANS FOR SECURING THE OBSTRUCTION MEANS IN THE PORT UNTIL A FIRST PREDETERMINED PRESSURE IS APPLIED TO THE OBSTRUCTION MEANS, SHOULDER MEANS IN THE CONDUIT FOR COOPERATION WITH A PLUG FOR APPLYING THE FIRST PREDETERMINED PRESSURE TO THE OBSTRUCTION MEANS TO REMOVE THE OBSTRUCTION MEANS THEREBY PERMITTING THE VALVE MEANS TO CLOSE, AND FRANGIBLE HOLDING MEANS FOR PREVENTING RELATIVE MOVEMENT BETWEEN THE VALVE BODY AND THE MANDREL UNTIL A SECOND PREDETERMINED PRESSURE IS APPLIED TO THE VALVE BODY, WHEREBY WHEN A SECOND PLUG IS INSERTED IN THE MANDREL TO LODGE IN THE ORIFICE AND A SECOND PREDETERMINED PRESSURE IS THEREBY IMPOSED ON THE VALVE BODY TO BREAK THE HOLDING MEANS, THE EXPANDING MEANS IS MOVED TO EXPAND THE PACKER.