Method and apparatus for lengthening a pipe string and installing a pipe string in a borehole

Abstract

The present invention generally relates to a method and an apparatus for connecting an add-on pipe segment to a pipe string to lengthen the pipe string using friction stir welding. The pipe string is suspended in a borehole using a spider or some other pipe suspending device, and the lower end of the pipe segment is brought into an abutting or nearly abutting relationship with the proximal end of the pipe string positioned above the pipe suspending device and above the rig floor. The friction stir welding machine is brought to well center to weld the abutment or gap between the pipe segment and the pipe string and join the pipe segment to the pipe string to lengthen the pipe string. In one aspect, the method includes friction stir welding an expandable pipe segment to an expandable pipe string to form a lengthened expandable pipe string. The pipe segment may be comprised of two or more pipe segments that have been friction stir welded or conventionally welded to form a pipe stand. After friction stir welding to lengthen the pipe string, the lengthened pipe string is lowered into the borehole and the proximal end of the lengthened pipe string is favorably positioned to abut or nearly abut a new add-on pipe segment for friction stir welding at the resulting abutment or gap. The friction stir welding process provides a highly reliable pipe joint for expansion.

1 . A method of lengthening a pipe string comprising the steps of:
 suspending a pipe string from a rig using a pipe suspending device;   positioning a pipe segment having an upper end and a lower end to be generally aligned with and in close proximity to or abutting the proximal end of the pipe siring at its lower end;   securing the lower end of the pipe segment in close proximity to or abutting the proximal end of the pipe string; and   friction stir welding the pipe segment to the pipe string to lengthen the pipe string.   
   
   
       2 . The method of  claim 1  further comprising the step of installing the lengthened pipe string in a borehole and radially expanding at least a portion of the pipe string within the borehole. 
   
   
       3 . The method of  claim 1  further comprising the step of securing the pipe segment in its position in close proximity to or abutting the proximal end of the pipe string by disposing an alignment clamp to radially expand within a portion of the bore of the pipe segment and a portion of the bore of the pipe string to grip the adjacent ends of the pipe segment and the pipe string. 
   
   
       4 . The method of  claim 1  further comprising the step of securing the pipe segment in its position in close proximity to or abutting the proximal end of the pipe string by disposing a first external clamp to close on and grip the lower end of the pipe segment and disposing a second external clamp to close on and grip the proximal end of the pipe string. 
   
   
       5 . The method of  claim 3  further comprising the step of axially adducting a first gripping portion of the alignment clamp toward a second portion of the alignment clamp to apply a preload to the abutment between the pipe segment and the pipe string before friction stir welding the pipe segment to the pipe string. 
   
   
       6 . The method of  claim 4  further comprising the step of axially adducting a the first external clamp toward the second external clamp to apply a preload to the abutment between the pipe segment and the pipe string before friction stir welding the pipe segment to the pipe string. 
   
   
       7 . The method of  claim 2  further comprising forcing an expansion mandrel having a diameter greater than the interior bore of the pipe string through the bore of the pipe string to radially expand the pipe string within the borehole. 
   
   
       8 . The method of  claim 2  further comprising rotating a rotary expansion tool within the pipe string to expand the pipe string over a substantial portion of its length after the pipe string has been substantially installed within the borehole. 
   
   
       9 . The method of  claim 1  further comprising the step of forming the proximal end of the pipe string for mating engagement with the lower end of the pipe segment to resist radial movement of one relative to the other during friction stir welding. 
   
   
       10 . The method of  claim 1  further comprising the step of powering a friction stir welding machine using pressurized fluid. 
   
   
       11 . The method of  claim 1  further comprising the step of powering a friction stir welding machine using electricity. 
   
   
       12 . The method of  claim 1  further comprising the step of pre-assembling the pipe segment to be joined to the pipe string from a plurality of shorter pipe segments joined by a process selected from the group of consisting of conventionally welding the segments, friction stir welding the segments, or a combination of one or more of these processes. 
   
   
       13 . The method of  claim 1  wherein the pipe suspending device is selected from a group consisting of a spider, a set of landing tables, a collar load support device, a dual elevator system used in conjunction with landing tables, or some combination of these. 
   
   
       14 . The method of  claim 1  further comprising the step of repeating the first four steps until the pipe string achieves the desired length, installing the pipe string in a borehole, and securing the pipe string in place by circulating a cement slurry or a cement substitute into the annulus between the exterior surface of the pipe string and the wall of the borehole. 
   
   
       15 . The method of  claim 1  further comprising the step of introducing a volume of fluid into the lengthened pipe string to prevent collapse or damage to the lengthened pipe string as it is lowered into a borehole. 
   
   
       16 . The method of  claim 1  further comprising the step of providing a mating interface to the abutting ends of the pipe segment and the pipe string to resist radial movement of one relative to the other after an abutment is formed. 
   
   
       17 . The method of  claim 15  further comprising the step of circulating the introduced fluid through the borehole by imposing a seal between the fluid conduit and the interior wall of the lengthened pipe string. 
   
   
       18 . An apparatus for joining a pipe segment to a pipe string comprising:
 a clamping assembly having a first clamp for gripping a pipe segment and a second clamp for gripping a pipe string, the first clamp being generally aligned with the second clamp;   a friction stir welding machine coupled generally intermediate the first clamp and the second clamp for radially disposing a rotatable probe into an abutment or a gap between a lower end of the pipe segment and a proximal end of the pipe string; and   an orbital movement assembly for moving the rotatable friction stir welding probe in a generally orbital path through the abutment or gap to create a joint between the pipe string and the pipe segment to lengthen the pipe string.   
   
   
       19 . The apparatus of  claim 18  wherein the friction stir welding machine is movably suspended within a frame that can be moved to the pipe string and supported on a rig floor. 
   
   
       20 . The apparatus of  claim 19  wherein the friction stir welding machine is powered by a motor operated with pressurized fluid. 
   
   
       21 . A method of joining a pipe segment to a pipe string on a rig comprising the steps of:
 suspending a pipe string from the rig using a pipe suspending device, a proximal end of the pipe string protruding generally upwardly from the pipe suspending device;   positioning an add-on pipe segment into alignment with the pipe string;   abutting a lower end of the pipe segment against the proximal end of the pipe string;   clamping the pipe string and the pipe segment to restrain the pipe string and the pipe segment in the abutting position; and   friction stir welding the abutment formed between the pipe string and the pipe segment to lengthen the pipe string.   
   
   
       22 . The method of  claim 21  further comprising the steps of:
 lifting the lengthened pipe string to unload the pipe suspending device;   lowering the lengthened pipe string from the rig; and   suspending the lengthened pipe string from the rig by reengaging the pipe suspending device.