Method and Apparatus For Treating A Well

Abstract

A tool for forming a valve seat within a well that is capable of catching an obstruction will prevent flow of fluid downstream of the seat. According to one embodiment of the invention, the seat is formed by expanding a sleeve with a ring positioned around its periphery or as a subsequent step in the process. As the sleeve is expanded over the ring, the seat is formed. Once the seat is formed, an obstruction in the form of a ball or dart is dropped down to the seat. In another embodiment, the sleeve acts as a stop for a secondary valve seat which catches the obstruction. In yet another embodiment, only a portion of the sleeve is expanded and an inlet portion of the sleeve includes a valve seat.

I claim: 
     
         1 . A tool for forming a valve seat within the casing of an oil and/or gas well capable of capturing an obstruction to thereby prevent flow of fluids downhole of the valve seat comprising:
 a. a sleeve formed of expansible material, said sleeve adapted to engage an inner surface of the casing;   b. a valve seat formed as part of the sleeve; and   c. a seal surrounding a portion of the sleeve.   
     
     
         2 . The tool for forming a valve seat as claimed in  claim 1  further including a thin strip of no-slip metallic material impregnated on an outer surface of the sleeve. 
     
     
         3 . The tool for forming a valve seat as claimed in  claim 1  further including a cap closing a downhole portion of the sleeve so that the tool can be pumped down into the well to a predetermined location. 
     
     
         4 . The tool as claimed in  claim 1  wherein the seal is positioned around the sleeve approximately at an inlet of the sleeve. 
     
     
         5 . The tool as claimed in  claim 1  wherein the valve seat is formed on an inlet portion of the sleeve. 
     
     
         6 . The tool as claimed in  claim 1  wherein the seal is swellable. 
     
     
         7 . The tool of  claim 1  wherein the seal surrounds an inlet portion of the sleeve, the valve seat being located at the inlet of the sleeve. 
     
     
         8 . The tool of  claim 1  wherein the sleeve includes an axially extending inlet portion which is surrounded by the seal, the inlet portion remaining unexpanded when a remaining portion of the sleeve is expanded during setting of the tool.