A North sea case study is discussed about a platform deployed 8" Tethered Tecno Plug that cut decommissioning costs. This marks the first known application of its kind and the longest Tethered Tecno Plug deployment to date at approximately 80 metres.
At the end of a platform’s productive life, it is essential that the asset be safely disconnected from neighbouring infrastructure so that decommissioning can proceed. Where a platform remains tied to another Operator’s field via live or potentially pressurised pipelines, this dependency can delay decommissioning and lead to unnecessary maintenance and management of non-operational assets.
In 2022, a southern North Sea platform faced this challenge. The associated well, owned by another Operator, had no near-term plug and abandonment plans, preventing the platform Operator from progressing. A STATS 8” Tethered Isolation Plug was therefore deployed from the platform to a subsea isolation point, marking the first known application of its kind and the longest tethered plug deployment to date at approximately 80 metres. Once set and a leak-tight isolation had been verified, the control umbilical and riser were cut, permanently abandoning the line and enabling topside and jacket removal activities to proceed.
By applying proven technology in a novel way and leveraging a large existing fleet, this solution provided a cost-effective method for platform-to-pipeline abandonment isolation during decommissioning, with zero vessel involvement otherwise required for remotely controlled isolation plugs.
Author: Neil Mackay