SBS Energy Services (SBS), in partnership with Helix Energy Solutions and with the help of a special tool named the ‘Crab Claw’, have successfully completed a multi-phase project to decommission approximately 29,000 ft of 10 inches by 6 inches insulated pipeline in the Gulf of Mexico setting a new offshore snubbing unit/hydraulic workover world record.
The project was carried at on the Ozona Garden Banks 515 location and consisted of retrieving and removing a Pipeline End Termination (PLET) to surface of a DP3 drilling intervention vessel. The second objective was to use a 340k snubbing unit to rig up and intervene inside the pipeline with an optimised drill pipe string to perform washing and flushing operations until reaching the second PLET. A cap was then installed on the first end of the pipeline and placed back in the original trench on the seafloor with the deployment rigging and drill string for permanent abandonment in-situ. The final task was to record the final pipeline position on the seafloor. The entire project took just 22 days.
Part of the operation was to clean out the flowline rather than cutting it into sections. This approach significantly reduced the number of critical subsea lifts and overall timeline for the cleanout and lay down. Performing the full cleanout in a single lift also required minimal onshore disposal of flowline components.
This deepwater pipeline cleanout utilised the Helix Q4000, an intervention and construction vessel, working in 3,287 ft of water. “To our knowledge, this has never been done before, especially considering the total cleanout depth of almost 29,000 ft with over 25,000 ft of that being lateral length on the ocean floor,” said Bobby Bray, President of SBS.
The highlight of the operation was to successfully trip in one time and trip out the drill string to the 28,789 ft actual drill pipe measurement (28,763 ft per procedure); 3,281 ft water depth, 25,069 ft lateral and flush the pipeline. Another characteristic that makes the project unique is that the pipeline lay on the sea floor is shallow (3,281 ft vertical) compared to a conventional well profile (est. 10,000 ft vertical).
The job also incorporated the special ‘Crab Claw’ tool that was designed, engineered, and manufactured to store torque energy, while washing and rotating operations were ongoing. “This was both a safety and an operational efficiency design. We stored the residual torque of pipe rotations while making up or breaking out subsequent joints. This saved measurable time and created a safer work environment,” commented Charles Overstreet, President of Omicron Project Consulting who provided the engineering design on the project.
“The pre-job planning, institutional knowledge and crew experience was critical to our success,” said Bray. “Kudos to our customer who gave us the time to prepare for the job. Our customers now know they have an environmentally safe and cost-efficient option for flowline cleanout compared to recovering the flowline and disposing of it onshore.”
The previous snubbing record depth of 23,800 ft was set in 2006 by Helix (then Cal Dive) on the Q4000 during the Mariner Energy Pluto pipeline clean out, making the SBS and Helix project the longest subsea flowline cleanout conducted via this method to date – a fantastic achievement for all the organisations and people involved.