METHOD AND APPARATUS FOR LENGTHENING A PIPE STRING AND INSTALLING A PIPE STRING IN A BOREHOLE
A method and an apparatus are provided to connect a pipe segment (22) to lengthen a pipe string (20) using friction stir welding. The pipe string is suspended in a borehole (6), and a lower end (22b) of the pipe segment (22) is brought into an abutting or nearly abutting relationship with a proximal end (20a) of the pipe string above the suspending device (16) and above a rig floor (14). A friction stir welding machine (40) welds the abutment or gap between the pipe segment and the pipe string to lengthen the pipe string. In one aspect, the method includes friction stir welding an expandable pipe segment to lengthen an expandable pipe string. The lengthened pipe string is lowered into the borehole and the new proximal end of the lengthened pipe string is positioned to abut or nearly abut a new pipe segment and friction stir welded.