Investing in Subsea Decommissioning Pays Off, Decom Engineering Finds

Decom Engineering has completed the first deployment of its largest subsea Chopsaw to date, achieving substantial time savings of almost 300% on a decommissioning job in the North Sea.

Following the $1.2 million (£1 million) investment to develop its largest subsea Chopsaw yet – the C1-46 – the Northern Ireland-based offshore decommissioning technology firm said the investment paid off following ‘impressive results’ on its first deployment.

Namely, the C1-46 Chopsaw was employed on a subsea infrastructure decommissioning project on behalf of DeepOcean in the Northern North Sea basin.

The project involved the removal of pipelines, control umbilicals, and various subsea structures from the seabed in water depths of up to 180 meters, each requiring precise and efficient cutting.

According to Decom Engineering, the C1-46 exceeded all expectations, averaging 15 cuts before requiring a blade change, therefore significantly reducing the need for recovery to the surface.

The Chopsaw, designed for operation in water depths of up to 2,000 meters and capable of cutting tubulars and other materials up to 46” diameter, completed 79 cuts on its first deployment, showcasing a 100% success rate.

Powered from topside and ROV using a Hydraulic Power Unit (HPU), reeler, hot stabs and control panel, the C1-46 was joined by a smaller C1-24 unit to complete the task.

Substantial time savings of almost 300% were achieved compared to using traditional diamond wire saws which typically have longer cut times and carry more risks, Decom Engineering said.

The C1-46 completed some cuts in as little as 20 minutes, while the C1-24 saw excelled in cutting super duplex and flexible risers – materials that traditional shears cannot handle.

Furthermore, Decom’s innovative approach to reducing seabed dredging time by modifying the saw’s clamps reduced dredge time from 3.5 hours to just 30 minutes, the company claims.

 “The C1-46 Chopsaw is a remarkable piece of subsea engineering which was designed, developed, and deployed in under six months, specifically for this North Sea decommissioning campaign.

“This project underlined our commitment to engineering innovation and underlined our credentials for pushing the limits of what’s achievable in subsea decommissioning. To efficiently cut through a submerged 1,042 mm reinforced concrete coated pipe is not without its challenges, but the C1-46 was more than up to this difficult task.

“It’s been a valuable learning experience and the performance of the C1-46 Chopsaw sets the benchmark for going on to roll out our technologies which offer multiple benefits to contractors and operators engaged in complex subsea decommissioning projects,” said Sean Conway, Decom Engineering’s Managing Director.