Whilst the coiled tubing technology continues to emerge as a versatile solution in the industry, it is often perceived as an expensive option by many operators. Offshore coiled tubing operations are usually more challenging than land CT operations due to involvement of several additional issues like requirement of Support Vessel, tighter equipment lay-out, higher lifting capacity requirements on site, sensitivity to weather/sea conditions etc. which may also have significant cost implications. With the expanding drilling limits in respect of operating depths, well trajectories, down hole pressures, hole sizes and other operating environment, the resulting wellbores are becoming increasingly challenging to down-hole service operations. The inability of the conventional ways of down-hole intervention like slick-line and e-lines to service such wellbores is opening up newer dimensions for coiled tubing applications. To cater to these increasingly challenging expectations, the coiled tubing size is gradually expanding and the length is extending, both demanding higher lifting capacities and bigger space on location.

There are various ways offshore coiled tubing operations can be managed, in some cases, even without a support vessel. However more often a support vessel is required for running smooth operation. There are various types of support vessels available in market from tiny little workboats to highly sophisticated service vessels. The economics of any support vessel strategy are often mistaken; a low cost vessel may not necessarily be an optimized solution in terms of the overall economics of operations. In continuous operations, it is also common to see that sometimes the rate of coiled tubing servicing over takes the rate of generation of work-load, thereby creating the situation of resource idling.

The present work demonstrates an analytical approach in formulating the right strategy on support vessel for offshore coiled tubing operations. It compares and evaluates various alternative modus operandi of running offshore coiled tubing operations and work its way up to identify the most appropriate strategy in terms of overall economics and safety considerations. The work also evaluates the sensitivity of this strategy on several technical, operational, organizational and environmental parameters, which commonly surround the actual working environment.

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