A UK North Sea operator presented a challenging opportunity for the development of a contingency recovery system to be designed for deployment from an intervention vessel. The main requirement of the contingency tool was that it be capable of recovering coiled tubing that is subsequently left in a subsea well after previously operating an emergency shutdown (ESD) system and securing the well.
Typically, when an ESD operation must be performed, requirements demand that the vessel be unlatched from the subsea wellhead within 60 seconds. When the vessel returns, the operator has to recover the coiled tubing that was left in the well. Unlike conventional operations, for this vessel-deployed endeavor, the injector head is located over the moonpool, a large opening in the middle of the vessel that gives the operator subsea access. Unfortunately, the moonpool poses an inherent human risk; thus there exists the desire to limit human interaction in this type of operation.
To reduce the human risk involved, a spoolable spear system that eliminates the need to break out the lubricator/riser multiple times was engineered. The system was designed to enable retrieval of the sheared coiled tubing and recovery of the coiled tubing and connected tools to the work reel without breaking a lubricator/riser connection. Specifically, after a dressing run is completed, the spoolable coiled tubing spear is able to stab into the dressed open end of the coiled tubing and recover the coiled tubing string back through the injector head and back onto the work reel.
With an ever increasing focus on safety, particularly offshore safety, this spoolable spear system presents an opportunity to reduce human intervention in work locations and to significantly reduce the risk of injury. A reliability feature of the contingency system is that all components stressed during operation are to be replaced after each run, making it a one-run system. Multiple sizes of this coiled tubing recovery system have been developed for efficient and effective interventions while encouraging footprint minimization. Field-testing details will be reviewed and discussed during the associated presentation.