Downhole blowout preventor

Abstract

The downhole flow control means or downhole blowout preventor (downhole BOP) of the present invention is adapted for use during reverse circulation drilling with both concentric drill pipe and concentric coiled tubing. The downhole BOP comprises an inner tube member having an inner passage therethrough and an outer casing forming an annular passage between the inner tube member and the outer casing. The inner passage and the annular passage of the downhole BOP is in fluid communication with the inner passage and annular passage, respectively, of the concentric drill pipe or concentric coiled tubing. The downhole BOP further comprises two valve means, preferably a check valve and a ball valve, for closing off the annular passage and the inner passage of the downhole BOP, respectively. In a preferred embodiment, the downhole BOP further comprises an electric actuator for opening and closing the ball valve.

1 . A downhole flow control means for use during reverse circulation drilling with a concentric drill string, said concentric drill string comprising an inner pipe or tube having an inner passage therethrough, and an outer pipe or tube surrounding said inner pipe or tube and forming an annular passage therebetween, comprising: 
 (a) an inner tube member, said inner tube member having an inner passage therethrough, and an outer casing surrounding said inner tube member and forming an annular passage therebetween;    (b) a first valve means located in the annular passage adapted to be moved from a closed position to an open position; and    (c) a second valve means located in the inner passage adapted to be moved from a closed position to an open position,    wherein said inner passage of said downhole flow control means is in fluid communication with said inner passage of the concentric drill string and said annular passage of said downhole flow control means is in fluid communication with said annular passage of said concentric drill string.    
   
   
       2 . The downhole flow control means of  claim 1  wherein said first valve means comprises a check valve.  
   
   
       3 . The downhole flow control means of  claim 2  wherein said check valve is moved from the closed position to the open position by means of pressure exerted on said valve by pumping air or fluid through the annular passage of the concentric drill string and the annular passage of the downhole flow control means.  
   
   
       4 . The downhole flow control means of  claim 1  wherein said second valve means comprises a ball valve.  
   
   
       5 . The downhole flow control means of  claim 4  wherein said downhole flow control means further comprises an actuating means for moving the ball valve from the closed position to the open position.  
   
   
       6 . The downhole flow control means of  claim 5  wherein said actuating means comprises a pneumatic actuator.  
   
   
       7 . The downhole flow control means of  claim 5  wherein said actuating means comprises a hydraulic actuator.  
   
   
       8 . The downhole flow control means of  claim 5  wherein actuating means comprises an electric actuator.  
   
   
       9 . The downhole flow control means of  claim 8  wherein said inner tube member of said downhole flow control means is made of steel and said inner pipe or tube of said concentric drill string is made from a conductive material selected from the group consisting of rubber, rubber and steel, fiberglass or composite material.  
   
   
       10 . The downhole flow control means of  claim 9  wherein said inner tube member of said downhole flow control means further comprises an electrically conductive wire wrapped around the entire length of said inner tube member and said inner pipe or tube of said concentric drill string further comprises an electrically conductive wire wrapped around the entire length of said inner pipe or tube.  
   
   
       11 . The downhole flow control means of  claim 4  wherein said ball valve is moved from the closed position to the open position by physically applying pressure to the concentric drill string and turning said concentric drill string either clockwise or counter-clockwise.