Abstract

This paper discusses an offshore coiled tubing (CT) application to address a complex well situation and well control issue. Multi-engineering designs and 100% yard testing were used successfully during this campaign.

Parted production tubing was identified some 50 m from the surface. The control line of the downhole safety valve failed and one barrier was lost in the well. This paper describes efforts to regain pressure integrity for a plug and abandonment (P&A) procedure in this live gas well. CT was inserted through the parted production tubing in an attempt to regain pressure integrity.

A carefully planned cement placement strategy was critical to operational success. Key challenges and solutions included the following:

  • Wellhead pressure (WHP), friction, and a highly deviated trajectory affected CT pulling capabilities. Therefore, extra-lightweight cement was used to reduce weight inside the CT.

  • The downhole safety valve failed to close, so the downhole tool was redesigned to help ensure that the tool would not stick.

100% Yard testing for the application was performed to simulate onsite, downhole operations.

Well pressure integrity is a primary priority for global operators. An option to regain pressure integrity was introduced and involved running CT and placing cement into the live well. A combination of multi-engineering designs aided this successful CT campaign. The CT was run through the parted production tubing and the failed downhole safety valve. The well was killed and extra-lightweight cement was successfully placed. The operator was able to regain pressure integrity and perform a P&A procedure. The success of this case study indicated that this procedure could be used for future downhole equipment and tubing failures in live gas wells.

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