Rigless Repair of Subsea Tubing Leaks Using Pressure-Activated Sealant

Abstract

Abstract BP policy specifies requirements for well barrier management throughout the life cycle of a well. Well barriers are specifically required to isolate energy sources within the earth from each other, the surface environment, and people. Annulus pressure management is fundamental to maintaining healthy well barriers and active monitoring assures the barriers are in place. In subsea wells, the only annulus that can be monitored in real time is between the tubing and production casing (aka A-annulus). When an anomaly is detected in the A-annulus, then a diagnostics and intervention program must be implemented to repair the suspected well integrity issue. In deepwater environments, repairing a well integrity issue with a rig can be costly and the traditional tools for well diagnostics and repair, such as wireline and coil tubing, are complex to deploy into subsea completions. Alternatives such as pressure-activated sealants have a proven track record repairing well integrity issues in dry tree wells. This technology is now being deployed to repair well integrity issues in subsea wells. This paper presents two case studies where pressure-activated sealants were used to successfully repair tubing by A-annulus (T × A) communication in a subsea wells. BP had utilized this technology with great success in its Alaska fields (SPE Papers10895 and 120978) and saw an opportunity to extend those learnings to subsea wells. These operations utilized innovative delivery techniques to enable sealant injection, placement, and activation downhole. Rigorous testing, simulation, and planning prior to starting the job increased confidence in the operational technique and reduced safety risks to the environment and the wells. Both efforts resulted in a successful repair of the well integrity issue. There were several benefits for using a pressure-activated sealant for these two interventions. The less complex non-rig interventions presented fewer safety and environmental risks and were completed with no HSE incidents. The non-rig repairs were completed for a small fraction of the cost of a conventional rig repair and rig time was kept available for drilling and completing new wells. Given its effectiveness and these benefits, the application of this technology may be especially useful for subsea wells with marginal remaining reserves where the relatively lower cost may help to optimize productive life and ultimate recovery. The integrity of a sealant repair can be monitored during the life of the well just like a conventional rig repair and a sealant repair does not preclude the ability to perform a conventional rig repair in the future.