Since the Bureau of Safety and Environmental Enforcement (BSSE) released and implemented the updated version of the Code of Federal Regulations (CFR) in recent years, operators now have the need to reenter wells that had been deemed as abandoned in the 1980’s, and perform operations to comply with the updated regulations.

All of these wells have surface plugs (either cement plugs or cast iron bridge plugs) that require milling in order to access the wellbores to be abandoned. The use of a pulling unit is generally the method used for these abandonment operations. However, the risks of having pressure trapped below those surface plugs, and the ability to maintain well control during milling operations with the pulling units poses a great concern to the Operators. Upon evaluation, Shell decided to use large outside diameter (OD) coiled tubing (CT) to mill the surface cement plugs and the cast iron bridge plugs. The use of CT enabled several operational advantages, such as the ability to handle potentially live well situations safely and efficiently, faster operations to mobilize (mob) from well to well, the use of larger bottom hole assemblies (BHA) with mills manufactured to drift the different casings 7-, 9 5/8- and 10 3/4-in inner diameter (ID), ensure optimal downhole motor (DHM) performance and to provide efficient removal of solids from the wellbore back to surface.

This paper describes the CT operations performed on two shallow waters platforms projects in the GoM for Shell, where a total of 9 wells were intervened using 2 3/8- and 2 7/8-in OD CT. The challenges encountered together with the developed solutions, equipment used, lessons learned are also discussed. Full compliance with BSSE regulations for well abandonment was the final result.