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.
