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

Abstract

A zone isolating and testing apparatus comprising an isolation tool and a downhole flow control means and a method of using such apparatus is disclosed. The zone isolating and testing apparatus is particularly useful for testing zones during reverse circulation drilling using concentric drill string such as concentric drill pipe or concentric coiled tubing. The isolation tool of the zone isolating and testing apparatus comprises an expandable packer means and is adapted to connect to concentric drill string near the drilling means. The downhole flow control means of the zone isolating and testing apparatus comprises two valves, one for closing off the annulus between the inner tube and outer tube of the concentric drill string and the other for closing off the inner space of the inner tube. The downhole flow control means is also adapted to connect to concentric drill string near the drilling means. During testing, the isolation tool seals off the annulus between the concentric drill string and the walls of the wellbore and the downhole flow control means seals off either the annulus between the inner tube and outer tube of the concentric drill string or the inner space of the inner tube of the concentric drill string.

1 . An apparatus for isolating a zone in a hydrocarbon formation for testing flow of hydrocarbons, formation fluids and/or drill cuttings during vertical, horizontal or directional reverse circulation drilling of a wellbore using concentric drill string, said concentric drill string comprising an inner tube situated inside an outer tube and forming an annulus therebetween, comprising: 
 (a) an isolation tool having an expandable and contractible packer means and adapted to be operably connected to said concentric drill string; and    (b) a downhole flow control means having a plurality of valve means for controlling the flow of hydrocarbons, formation fluids and drill cuttings through the annulus, the inner tube or both and adapted to be operably connected to said concentric drill string.    
   
   
       2 . The apparatus of  claim 1  wherein said concentric drill string comprises joints of concentric drill pipe.  
   
   
       3 . The apparatus of  claim 1  wherein said concentric drill string comprises concentric coiled tubing.  
   
   
       4 . The apparatus of  claim 1  wherein said downhole flow control means is operably connected to said concentric drill string below said isolation tool.  
   
   
       5 . The apparatus of  claim 1  wherein said downhole flow control means is operably connected to said concentric drill string above said isolation tool.  
   
   
       6 . The apparatus of  claim 2  wherein said isolation tool and said downhole flow control means are separated from each other by one or more joints of concentric drill pipe.  
   
   
       7 . The apparatus of  claim 1  wherein said inner tube is made of a rubber material, rubber and steel, fiberglass or other composite material and comprises electrical wires and said packer means of said isolation tool expands or contracts by means of an electric current delivered by the electrical wires of the inner tube.  
   
   
       8 . The apparatus of  claim 1  wherein said packer means comprises an inflatable ring.  
   
   
       9 . The apparatus of  claim 8  wherein said inflatable ring expands or contracts by pumping fluids into or out of the inflatable ring.  
   
   
       10 . The apparatus of  claim 1  wherein said isolation tool and said downhole flow control means are further adapted to be connected to each other.  
   
   
       11 . A method for isolating a zone in a hydrocarbon formation for testing flow of hydrocarbons, formation fluids and/or drill cuttings during vertical, horizontal or directional reverse circulation drilling of a wellbore using concentric drill string, said concentric drill string comprising an inner tube situated inside an outer tube and forming an annulus therebetween, comprising: 
 (a) sealing off an outside annulus formed between a wall of said wellbore and an outer surface of said concentric drill string to form an isolated testing zone;    (b) sealing off one of said annulus between the outer tube and the inner tube of the concentric drill string or said inner space of the inner tube of the concentric drill string;    (c) allowing hydrocarbons, formation fluids and/or drill cuttings present in said isolated testing zone to flow through the other of said annulus between the outer tube and the inner tube of the concentric drill string or said inner space of the inner tube of the concentric drill string to the surface of said wellbore; and    (d) measuring the amount of hydrocarbons, formation fluids and/or drill cuttings present in said isolated testing zone.    
   
   
       12 . The method of  claim 11  wherein the outside annulus is sealed off by means of an isolation tool comprising an expandable and contractible packer means.  
   
   
       13 . The method of  claim 12  wherein said packer means is expanded and contracted by means of an electrical current.  
   
   
       14 . The method of  claim 12  wherein said packer means is expanded and contracted by means of addition of fluid into or removal of fluid from the packer means.  
   
   
       15 . The method of  claim 11  wherein the annulus between the outer tube and the inner tube of the concentric drill string or the inner space of the inner tube of the concentric drill string is sealed off by means of a downhole flow control means comprising a plurality of valve means.  
   
   
       16 . The method of claim  111  wherein said concentric drill string comprises joints of concentric drill pipe.  
   
   
       17 . The method of  claim 11  wherein said concentric drill string comprises concentric coiled tubing.