Method and apparatus for isolating and testing zones during reverse circulation drilling

Abstract

An isolation tool for use with a concentric drill string for isolating a zone in a wellbore for testing is provided comprising a center tube and an outer casing forming an annular conduit therebetween and an expandable and contractible packer for sealing off an outside annular passage formed between a wall of the wellbore and an outer surface of the concentric drill string, whereby the isolation tool is adapted to be operably connected to the concentric drill string such that the isolation tool is in fluid communication with the concentric drill string.

1 . An isolation tool for use with a concentric drill string for isolating a zone in a wellbore for testing, comprising: 
 (a) a center tube and an outer casing, said center tube and outer casing forming an annular conduit therebetween; and    (b) an expandable and contractible packer means for sealing off an outside annular passage formed between a wall of said wellbore and an outer surface of said concentric drill string; whereby the isolation tool is adapted to be operably connected to the concentric drill string such that the isolation tool is in fluid communication with the concentric drill string.    
   
   
       2 . The isolation tool as claimed in  claim 1 , wherein said packer means expands or contracts by means of an electric current.  
   
   
       3 . The isolation tool as claimed in  claim 1  wherein said packer means comprises an inflatable ring.  
   
   
       4 . The isolation tool as claimed in  claim 3  wherein said inflatable ring expands or contracts by pumping fluids into or out of the inflatable ring.