Abstract
The Eni Nikaitchuq field development on the North Slope of Alaska consists of the Spy Island Drillsite (SID) artificial island, tied back to shore at the Oliktok Point Pad (OPP) production facility via a 3.6-mile-long buried offshore flowline bundle which contains a 14x18-in pipe-in-pipe (PIP) production flowline. In late 2017, the presence of internal corrosion was detected in the 14-in production flowline, and a repair of the line was performed. This paper presents the work performed to complete the repair, and the engineering and construction challenges overcome by the project team to ensure a timely and reliable repair was executed.
The engineering work was initiated in early 2018 and included initial integrity checks of the 14-in flowline, followed by an evaluation of feasible repair options, and the selection of the preferred repair option, which was to install a 10-in steel linepipe inside of the original 14-in flowline to create a pipe-in-pipe-in-pipe (PIPIP).
The selected repair methodology allowed the total repair project to be undertaken in six months, from the time of repair concept definition to restart of production. Actual production downtime was limited to only seven weeks, with the insertion of the 10-in repair pipe itself taking only ten days. Production has been successfully ongoing since completion of the repair and resumption of operations at Nikaitchuq.
It is believed that this is the first time such a repair has been successfully undertaken, where a steel flowline several miles long has been installed inside of an existing flowline and serves as a good example of how innovative engineering and construction methodologies can be reliably implemented in the Arctic.
