Coil Tubing Services, a Schlumberger company, proposed CT riserless operations in P&A wells after the zonal and casing packer isolation had been successfully set and tested. Engineering and operational evaluations were performed to address CT string integrity, bottomhole assembly, surface CT stack rig-up, remote operating vehicle use to string the CT into the wellbore, CT depth correlation, cement slurry design, and proper fluid placement.
A total of 14 subsea CT riserless interventions have been completed as part of this campaign without HSE incidents or CT string failures, saving 40% in operational time and complying with federal safety regulations.