Ariserless coil tubing (CT) technique applied in open water could lower the cost of subsea well interventions. Developer Island Offshore (Island) has proven the system during two campaigns offshore Norway, one involving a test for shallow gas. The company is currently working to extend applications to various types of intervention, including P&A operations, following interest from various North Sea operators. The equipment spread has so far been deployed from two of the company's monohull light well intervention vessels. There is no requirement for a rigid workover riser: instead, the coil tubing is kept in tension between the vessel and the system's subsea injector via a second injector onboard the vessel. Pressurized drilling fluid pumped into the coil tubing drives the mud motor, causing the bit to rotate. The ROV-operated subsea injector pushes the coil tubing into the well forming weight on bit, and pulls the coil tubing out once drilling has been completed.
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