Separation string for the separation of hydrocarbon from contaminants in a wellbore and method of assembling same

Abstract

A separation string includes an outer pre-drilled liner and an inner assembly disposed within the outer pre-drilled liner. The inner assembly includes a shear-out member and a filter assembly for separating hydrocarbons from contaminants. A swivel slack joint is connected to an upper end of the inner assembly to facilitate mounting of a top sub to the inner assembly and to the outer pre-drilled liner without producing rotation of the inner assembly. The swivel slack joint includes an outer sleeve connected to the inner assembly, and a tube connected to the top sub. The tube is freely rotatable and vertically slidable relative to the sleeve. The shear-out member is designed to shear at a load less than a load which would cause other components of the inner assembly to shear, and to present, upon shearing, a portion configured to be grasped by a retrieval tool.

What is claimed is:  
     
         1 . A separation string for separating hydrocarbons from contaminants in a wellbore, comprising: 
 an outer pre-drilled liner including bottom and top ends spaced apart along a vertical axis of the casing;    an inner assembly disposed inside of the pre-drilled liner and comprising a filter assembly including at least one membrane unit adapted to separate at least one hydrocarbon from at least one contaminant;    a top sub threadedly attached to the top end of the outer pre-drilled liner; and    a swivel slack joint interconnecting the top sub and the inner assembly, the swivel slack joint including first and second telescopingly arranged elements, a bottom and of the first element attached to a top end of the inner assembly, and a top end of the second element threadedly attached to the top sub, the second element being mounted to the first element for vertical sliding movement relative thereto, and being rotatable relative to the first element about the longitudinal axis, to permit the top sub to be screwed to the outer pre-drilled liner without rotating the inner assembly.    
     
     
         2 . The separation string according to  claim 1  wherein the first element of the swivel slack joint comprises a sleeve having a screw thread at its bottom end; the second element comprising a tube slidably mounted inside the sleeve and having a screw thread at its top rear end.  
     
     
         3 . The separation string according to  claim 2  wherein the swivel slack joint further includes an insert attached to a top end of the sleeve and defining a shoulder for limiting rearward movement of the tube relative to the sleeve.  
     
     
         4 . The separation string according to  claim 3  wherein the insert is threadedly secured to the top end of the sleeve and further attached thereto by set screws for preventing unscrewing of the insert.  
     
     
         5 . The separation string according to  claim 3  wherein one of the sleeve and the tube carries seals bearing against the other of the sleeve and the tube.  
     
     
         6 . The separation string according to  claim 5  wherein the seals comprise O-rings mounted on an outer periphery of a front portion of the tube.  
     
     
         7 . The separation string according to  claim 1  wherein the inner assembly further includes a shear-out member having a shearing portion which shears at a predetermined load less than a load at which other components of the inner assembly would shear, the shear-out member including a portion which is exposed in response to a shearing of the shearing portion and which is configured to be grasped by a retrieval tool.  
     
     
         8 . The separation string according to  claim 1  wherein the membrane unit comprises an outer pre-drilled tube, and a pair of end caps screwed to opposite ends of the tube to retain a membrane inside of the tube.  
     
     
         9 . The separation string according to  claim 8  wherein the membrane unit further comprises an inner pre-drilled tube disposed inside of the membrane.  
     
     
         10 . The separation string according to  claim 1  wherein the inner assembly further includes a latch assembly for latching the inner assembly to the outer pre-drilled liner.  
     
     
         11 . A separation string for separating hydrocarbons from contaminants in a wellbore, comprising: 
 an outer pre-drilled liner including bottom and top ends spaced apart along a vertical axis of the pre-drilled liner;    an inner assembly disposed inside of the casing and comprising: 
 a latch member for latching the inner assembly to the outer pre-drilled liner casing;  
 a filter assembly comprising at least one membrane adapted to separate at least one hydrocarbon from at least one contaminant, and  
 a shear-out member for shearing at a predetermined load less than a load which would fracture the other components of the inner assembly and including a portion which becomes exposed in response to a shearing of the shear-out member and configured for being grasped by a retrieval tool; and  
   a swivel slack joint interconnecting the top sub and the inner assembly, the swivel slack joint including first and second telescopingly arranged elements, a bottom end of the first element attached to a top end of the inner assembly, and a top end of the second element threadedly attached to the top sub, the second element being mounted to the first element for vertical sliding movement relative thereto, and being rotatable relative to the first element about the longitudinal axis, to permit the top sub to be screwed to the outer casing without rotating the inner assembly.    
     
     
         12 . A method of assembling a separation string, the separation string including an outer pre-drilled liner and an inner assembly disposed within the outer pre-drilled liner, the pre-drilled liner including bottom and top ends spaced apart along a longitudinal axis of the pre-drilled liner, the inner assembly comprising a filter assembly including at least one membrane unit for separating at least one hydrocarbon from at least one contaminant, the method comprising the steps of: 
 A. providing a swivel slack joint in the casing at a top end of the inner assembly, the swivel slack joint including first and second telescopingly arranged elements, the second element being slidable relative to the first element along the vertical axis, and rotatable relative to the first element about that axis;    B. attaching a bottom end of the first element to a top end of the inner assembly;    C. screwing a top sub to a top end of the second element; and    D. screwing the top sub to a top end of the outer pre-drilled liner while causing the first sub to rotate the second element relative to both the first element and the inner assembly about the longitudinal axis, to prevent rotation of the inner assembly.