Safe decontamination and disposal of FPSO subsea infrastructure and produced water
Decommissioning offshore assets is complex and strictly regulated. For their UK decommissioning programme, the operator required the safe receipt, decontamination and disposal of subsea infrastructure and large volumes of produced water from an FPSO and associated fields.
The scope covered the decommissioning and processing of contaminated produced water, flushing fluids and more than 2,000 tonnes of subsea materials - including risers, umbilicals, concrete mattresses, hydrocarbons and debris - distributed across multiple UK ports. Our client required delivery of a compliant, cost-effective and fully coordinated solution across multiple locations, without compromising safety or schedule.
Client
Major upstream oil and gas operator
Scope
Decommissioning, Environmental Services, NORM Management
Location
UK
Duration
Multi-phase, nationwide programme
At a glance
- Delivered a fully compliant, end-to-end decommissioning solution for FPSO subsea infrastructure and produced water across multiple UK ports, safely managing over 2,000 tonnes of materials and 2,400 tonnes of produced water.
- Coordinated a complex, multi-location programme through a single project management point, integrating logistics, quayside operations, industrial cleaning, waste and specialist NORM management with a UK-wide supply chain.
- Completed the project on time, within budget and with zero HSSEQ incidents, reducing operational complexity, minimising waste and maximising material recovery in line with regulatory and circular economy requirements.
Approach
We developed a turnkey, end-to-end solution by combining in-house environmental expertise, logistics capability and materials management with a collaborative UK-wide supply chain. A dedicated ASCO Project Manager acted as the single point of contact, coordinating all stakeholders and work scopes.
Six onshore work scope packages were delivered across several UK locations, from the Port of Tees in Northern England through to the Port of Cromarty Firth in Northern Scotland. We took an integrated approach across our solutions, including ships agency, quayside receipt and handling from our base in Peterhead, industrial cleaning, waste management and specialist NORM management.
Produced water operations were executed from the Port of Teesside, with 2,400 tonnes of produced water and flushings safely received and managed in line with environmental regulations. Subsea materials were received at the Port of Blyth, where 1,675 tonnes were handled across three vessel calls into a dedicated decommissioning area.
Working closely with partners, materials were segregated, downsized and cut, including NORM-contaminated risers and umbilicals. We provided a Radiation Protection Supervisor to oversee all on-site NORM activities. Contaminated materials were transported to our NORM processing facility in Aberdeen for decontamination prior to recycling, while NORM-free materials were recycled directly from the port.
Impact
The project was delivered safely, on time and within budget, meeting all client and regulatory requirements. Through planning, coordination and partnership, we reduced operational complexity, cut vessel sailing times, minimised waste and maximised material recovery in line with circular economy principles.
With zero HSSEQ incidents reported, we managed this large-scale, multi-location decommissioning project while maintaining clear communication, strong governance and consistent standards nationwide.
- 1,700 tonnes of subsea materials received over the quayside
- 878 metres of risers decontaminated
- 135 tonnes of containerised waste processed
- 2,400 tonnes of produced water and flushings safely managed
- 0 HSSEQ incidents
This decommissioning project brought together integrated services, experienced project management and a collaborative UK supply chain to deliver safe, responsible and cost-effective outcomes at scale.