Large Diameter Coiled Tubing Becomes Available Safely Offshore Through a Newly Developed Spoolable Connector: Case Histories and Field Implementation

摘要

Coiled Tubing operations in the North Sea are regularly challenged by crane lift capacity limitations when attempting to bring coiled tubing reels onboard. Very often the crane capacity or weather conditions determine the CT size to be used for the application, leading to operations conducted with less then the optimum CT size. The Norwegian sector generally has larger capacity cranes but most operations regularly involve the use of large OD coiled tubing (2.375" or 2.875"). The lengths required can cause logistical problems due to the lifting weights of the CT reels used. Current methods utilised for keeping weights as low as possible involve using so called split reel systems and thin-walled high strength parallel CT strings (i.e. constant wall thickness). While these weight reducing measures have proven themselves for many years now in the Norwegian sector, they can not resolve equipment weight issues in all cases. The joining of 2 or more separate strings together offshore by installing butt welds has been standard practice in the UK sector for many years now, mainly involving CT sizes of up to 1.75". In the Norwegian sector, butt-weld failures have occurred when using larger CT sizes and operators have been seeking a viable option to butt-welding, especially for larger OD CT.In response to a direct request by the BJ Services North Sea operations departments, BJ Services Coiled Tubing Research & Engineering group in Calgary, Canada have developed and commercialised a LCF (Low Cycle Fatigue) Spoolable Connector to replace offshore butt-welding and resolve weight issues associated with heavy CT reels.