The number of new subsea-completed wells is increasing rapidly. At the same time, existing subsea field developments are entering more challenging phases of production with wells demanding a higher intervention frequency in order to maintain production and/or increase recoverable reserves. Consequently the demand for performing coiled tubing (CT) interventions in such wells is increasing. As an indication of this trend, one operator in Norway has seen a doubling of CT interventions in subsea wells in 2003 compared to previous years.

Today the most common installations available to perform CT interventions on subsea wells are semisubmersible rigs that are primarily designed for drilling and completion activities. The challenges of interfacing with and performing CT operations from these "semisubmersibles" are well documented (1 ). Such challenges relate mainly to restricted access and space around the hoisting systems and, even more importantly, to the relative motion (primarily heave) that exists between the "fixed" wellhead/riser and the moving installation.

This paper describes newly introduced equipment and techniques that are now considered field tested to improve coiled tubing, semisubmersible operations by

  • Reducing personnel exposure to safety hazards

  • Reducing equipment exposure to damage hazards

  • Increasing efficiency and the operational window with respect to heave conditions

Items to be described and discussed in this regard are:

  • A latest generation lifting frame with integrated stripper crash frame and stabbing guide

  • Revolutionary use of a new slip joint system that effectively cancels out the effect of heave during critical phases of the operations

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