Apparatus for setting bridge plugs

Claim 1

APPARATUS FOR FORMING A BRIDGE PLUG IN A WELLBORE CONTAINING A STRING OF TUBING WHICH COMPRISES: (A) AN ELONGATED HEATING ELEMENT; (B) MANS FOR LOWERING SAID HEATING ELEMENT INTO SAID WELLBORE THROUGH SAID TUBING AT THE END OF A CABLE AND ENERGIZING SAID ELEMENT FROM THE EARTH''S SURFACE; (C) A BASKET SUPPORTED AT THE LOWER END OF SAID HEATING ELEMENT, SAID BASKET INCLUDING EXPANSIBLE MEMBERS CAPBEL OF PASSING THROUGH SAID TUBING AND EXPANDING OUTWARDLY IN CONTACT WITH THE SURROUNDING WELLBORE WALL; (D) A FUSIBLE MATERIAL HAVING A MELTING POINT BETWEEN ABOUT 150*F. AND ABOUT 700*F. SUPPORTED ADJACENT SAID HEATING ELEMENT ABOVE SAID BASKET, SAID FUSIBLE MATERIAL BEING PRESENT IN SUFFICIENT QUANTITY TO FILL SAID BASKET AND FORM AN IMPERMEABLE PLUG ABOVE THE BASKET AFTER SAID MATERIAL HAS MELTED AND DROPPED INTO THE BASKET; AND (E) MEANS FOR DISCONNECTING SAID HEATING ELEMENT FROM SAID BASKET WITHIN SAID WELLBORE AFTER SAID IMPERMEABLE PLUG HAS BEEN FORMED.