Method and apparatus for cementing a well using concentric tubing or drill pipe

Abstract

An apparatus and method for cementing a well using concentric drill string, e.g., concentric drill pipe, concentric coiled tubing and the like is disclosed. Concentric drill string comprises an inner string and an outer string, forming an annular conduit therebetween. Cementing apparatus comprises an isolation cementing tool and a cementing flow control means. The isolation cementing tool has a center tube and an outer casing forming an annular conduit therebetween, and an expandable packer means surrounding the outer casing. The cementing flow control means has a center tube and an outer casing forming an annular conduit therebetween, and a plurality of check valves positioned in either the center tube, within the annular conduit between the inner tube and the outer casing, or both.

1 . An apparatus for cementing a zone in a wellbore formation with cement, comprising: 
 (a) a first concentric drill string comprising an inner string having an inner conduit and situated within an outer string to form an annular conduit therebetween;    (b) an isolation cementing tool having an expandable and contractible packer means therearound, and adapted to be operably connected to said concentric drill string such that the isolation cementing tool is in fluid communication with both said conduits; and    (c) a cementing flow control means having a plurality of valve means for controlling the flow through the annular conduit or the inner conduit, or both, and adapted to be operably connected to said concentric drill string such that the cementing flow control means is in fluid communication with both said conduits.    
   
   
       2 . The apparatus of  claim 1  wherein said first concentric drill string comprises joints of concentric drill pipe.  
   
   
       3 . The apparatus of  claim 1  wherein said first concentric drill string comprises concentric coiled tubing.  
   
   
       4 . The apparatus of  claim 1  wherein said cementing flow control means is operably connected to said first concentric drill string by being operably connected to the cementing isolation tool.  
   
   
       5 . The apparatus of  claim 1  further comprising a second concentric drilling string wherein said second concentric drilling string is operably connected to both said isolation cementing tool and said cementing flow control means.  
   
   
       6 . The apparatus of  claim 1  wherein said inner string is made of a rubber material, a mixture of rubber and steel, fiberglass or other composite material and comprises electrical wires, and said packer means of said isolation cementing tool expands or contracts by means of an electric current delivered to the isolation cementing tool by the electrical wires of the inner string.  
   
   
       7 . The apparatus of  claim 1  wherein said packer means comprises an inflatable ring.  
   
   
       8 . The apparatus of  claim 7  wherein said inflatable ring expands or contracts by pumping fluids into or out of the inflatable ring.  
   
   
       9 . The apparatus of  claim 1  wherein said cementing flow control means comprises a center tube and an outer casing, and wherein the inner diameter of said center tube is reduced at some point.  
   
   
       10 . The apparatus of  claim 1  further comprising a surface flow control means positioned at or near the surface of the wellbore for preventing the flow of hydrocarbons from the wellbore.  
   
   
       11 . The apparatus of  claim 1  further comprising a downhole flow control means positioned at or near the bottom of the concentric drill string for preventing the flow of hydrocarbons from the inner conduit, the annular conduit or both to the surface of the wellbore.  
   
   
       12 . A method for cementing a zone in a wellbore formation with cement, comprising: 
 (a) providing a concentric drill string comprising an inner string having an inner conduit and situated within an outer string to form an annular conduit therebetween;    (b) pumping cement down one of the inner or annular conduits of the concentric drill string to the zone to be cemented;    (c) sealing off an outside annulus formed between a wall of said wellbore and an outer surface of said concentric drill string at a position above the zone desired to be cemented to prevent the flow of cement therethrough from the zone; and    (d) sealing off the other of the inner or annular conduits of the concentric drill string to prevent the flow of cement therethrough from the zone.    
   
   
       13 . The method of  claim 12  further comprising adding a cementing plug to the unsealed conduit after all the cement has been pumped therein.  
   
   
       14 . The method of  claim 13  further comprising pumping a first fluid through the unsealed conduit after the addition of the cementing plug to assist in pushing the cement through the unsealed conduit and into the zone in the wellbore formation.  
   
   
       15 . The method of  claim 14  further comprising preventing the cementing plug from exiting into the wellbore.  
   
   
       16 . The method of  claim 15  further comprising opening the sealed conduit and pumping a second fluid therethrough such that the second fluid is reverse circulated back up the unsealed conduit thereby removing the cementing plug and first fluid from the unsealed conduit to the surface of the wellbore.  
   
   
       17 . The method of  claim 12  wherein the outside annulus is sealed off by means of an isolation cementing tool comprising an expandable and contractible packer means.  
   
   
       18 . The method of  claim 17  wherein said packer means is expanded and contracted by means of an electrical current.  
   
   
       19 . The method of  claim 18  wherein said packer means is expanded and contracted by the addition of fluid into or the removal of fluid out of the packer means.  
   
   
       20 . The method of  claim 12  wherein the other of the inner or annular conduits of the concentric drill string are sealed off by means of a cementing flow control means comprising a plurality of valve means.  
   
   
       21 . The method of  claim 12  wherein said concentric drill string comprises joints of concentric drill pipe.  
   
   
       22 . The method of  claim 12  wherein said concentric drill string comprises concentric coiled tubing.  
   
   
       23 . The method of  claim 12  further comprising providing a downhole flow control means positioned at or near the bottom of the concentric drill string for preventing flow of hydrocarbons from the inner conduit, the annular conduit or both to the surface of the wellbore.  
   
   
       24 . The method of  claim 12  further comprising providing a surface flow control means positioned at or near the surface of the wellbore for preventing flow of hydrocarbons from the outside annulus.