Coil tubing injector for injecting tubings of various diameters

Abstract

A multi coil tubing injector includes a frame structure and a pair of gripper chain drives mounted to the frame structure. The pair of gripper chain drives are disposed in a common plane and spaced apart from each other, and have gripping blocks adapted to engage one or more of at least three differently-sized coil tubing strings to inject the coil tubing strings into, or extract them from, a subterranean well. The coil tubing injector assembly reduces a time required to perform many downhole operations, and therefore reduces a cost of well completion, stimulation and re-completion.

1 . A coil tubing injector assembly comprising: 
 a frame structure for mounting above a wellhead; and    at least one gripper chain drive system mounted to the frame structure and having a plurality of opposed gripping blocks adapted to grip at least one of at least three differently-sized coil tubing strings for injecting the coil tubing strings into and extracting the coil tubing strings from a subterranean well.    
   
   
       2 . The assembly as claimed in  claim 1  wherein each gripping block comprises at least one gripping surface adapted to grip one of the plurality of coil tubing strings.  
   
   
       3 . The assembly as claimed in  claim 2  wherein the gripping surface is concave.  
   
   
       4 . The assembly as claimed in  claim 3  comprising a single gripper chain drive system having a pair of opposed gripper chain drives, each gripper chain drive including a plurality of substantially identical gripping blocks.  
   
   
       5 . The assembly as claimed in  claim 4  wherein the gripping blocks have at least three gripping surfaces.  
   
   
       6 . The assembly as claimed in  claim 5  wherein each gripping block has three differently-sized gripping surfaces for gripping at least one of three differently sized coil tubing strings.  
   
   
       7 . The assembly as claimed in  claim 5  wherein each gripping block has four differently-sized gripping surfaces for gripping at least one of four differently-sized coil tubing strings.  
   
   
       8 . The assembly as claimed in  claim 5  wherein each gripping block has five differently-sized gripping surfaces for gripping at least one of five differently-sized coil tubing strings.  
   
   
       9 . The assembly as claimed in  claim 3  comprising at least three independently drivable gripper chain drive systems, each gripper chain drive system having a pair of opposed gripper chain drives, each gripper chain drive system having a plurality of substantially identical gripping blocks.  
   
   
       10 . The assembly as claimed in  claim 9  wherein each gripping block has a single gripping surface.  
   
   
       11 . The assembly as claimed in  claim 10  comprising three gripper chain drive systems each having a differently-sized gripping surface.  
   
   
       12 . The assembly as claimed in  claim 10  comprising four gripper chain drive systems each having a differently-sized gripping surfaces.  
   
   
       13 . The assembly as claimed in  claim 10  comprising five gripper chain drive systems each having a differently-sized gripping surface.  
   
   
       14 . The assembly as claimed in  claim 1  wherein the at least one gripper chain drive system comprises a pair of opposed gripper chain drives, each gripper chain drive having a drive sprocket mounted to a drive shaft, each drive shaft being coupled to a motor whereby the drive shafts of the opposed gripper chain drives are rotated at a same angular velocity but in opposite rotational directions.  
   
   
       15 . The assembly as claimed in  claim 14  wherein each gripper chain drive further comprises: 
 an idle sprocket mounted to an idle shaft; and    a gripper chain engaged with the drive sprocket and the idle sprocket, the gripper chain having the gripping blocks attached around an outer periphery of the gripper chain.    
   
   
       16 . The assembly as claimed in  claim 15  wherein each gripper chain drive further comprises a pressure beam supported by the frame structure and movable with respect to the frame structure, the pressure beam being adapted to support the gripper chains while the gripper chains grip the coil tubing string.  
   
   
       17 . The assembly as claimed in  claim 16  further comprising a roller chain system operatively mounted to the pressure beam for reducing friction between the pressure beam and the gripper chain.  
   
   
       18 . The assembly as claimed in  claim 17  wherein the pressure beam is connected to an actuator mounted to the frame structure for moving the pressure beam.  
   
   
       19 . A method of injecting or extracting one of at least three differently-sized coil tubing strings into or from a subterranean well using a single coil tubing injector, comprising the steps of: 
 gripping at least one of the at least three differently-sized coil tubing strings with at least one of at least three differently-sized gripping surfaces formed on gripping blocks attached to opposed gripper chains; and    driving the opposed gripper chains at substantially the same angular velocity in opposite rotational directions to inject or extract the at least one of the at least three coil tubing strings into or from the well.    
   
   
       20 . The method as claimed in  claim 19  further comprising a step of actuating pressure beams to force the gripping surfaces of the gripper chains against the at least one of the at least three coil tubing strings.