CNR Murchison Decommissioning

Location: CNR Murchison Platform, Offshore Northern sector of North Sea

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Aker Solutions/ CNRI

Scope of Work

NRC were awarded the Cleaning and Waste Management contract by Aker Solutions during the Engineering-Down phase of Decommissioning CNRI’s Murchison Platform and later were contracted direct to the operator for the final preparation for removal of topsides.

From the project commencement (Q1 2013) NRC provided project management services, working within the Client office as part of an integrated Aker Solutions team. From FEED Study phase NRC had been consulting on and providing key waste management and cleaning services and will continue to do so until offshore close-out.

During the Engineering-Down phase, NRC delivered essential descaling of pipework and vessels to remove hydrocarbon deposits as part of a phased decommissioning project.

Scopes then extended to include cold cutting, NORM management & descaling, waste treatment and also atmospheric monitoring to ensure required 10% lower explosive limits (LEL) were not exceeded.

NRC provided high-pressure water jetting services in order to meet the Client’s required cleanliness standard, removing the risk of an explosive atmosphere being formed, preventing hydrocarbon or chemical spills to sea and unnecessary exposure to personnel for the remainder of the decommissioning process.

Throughout the cleaning works, NRC utilised a closed-loop cleaning system in order to capture all washings, treat the derived waste in order to remove hydrocarbons and recycle the water for further cleaning. Over the course of the project, the unit (fitted with a flow meter) recycled just over 1,500,000 Litres of water, with less than 100,000 Litres of contaminated water being returned to shore for subsequent treatment and disposal.

Valves and other sections of pipework removed during the engineering-down process were often contaminated with NORM/ LSA Scale. As such NRC provided Radiation Protection Supervisors (RPS) to monitor and manage contaminated items, update the platforms storage log and also oversee NRC teams to decontaminate items on site. Removed scale could then be discharged to sea under the platform’s discharge permit, providing a saving against high onshore NORM disposal costs.

Prior to the removal of platform topsides, the Client requested that atmospheric testing was carried out on all systems to ensure that the 10% threshold of the LEL were not exceeded. NRC provided dedicated gas testing personnel to the platform, whose duties were to test all engineered-down systems and document any rises in detectable gases.

 

Technical Challenge

  • Timeline – critical path project
  • Project management, resourcing, planning and scheduling
  • SIMOPS
  • Hazardous waste – removal of NORM, oil and hazardous chemicals
  • Working at height and confined space working

 

Restrictions / Considerations:

  • Co-ordinating and scheduling of works to meet the requirements of the overall programme
  • No available storage facilities for waste washings, and limited supply of potable water
  • Hazardous environment – Vessel Entry Working, access and egress
  • Harsh weather conditions – 240km North-East of Shetland

 

Key Facts

  • Project Engineer worked as part of an integrated team within the Client’s office
  • Multi-skilled offshore workforce provided in order to maximise productivity
  • Use of closed-loop cleaning technology to reduce oily waste washings shipped to shore for treatment/ disposal by 1,400,000 Litres (Saving to the Client of approx. £210,000)
  • Zero uncontrolled discharges to sea
  • 38,000 man hours worked, Zero LTI’s and Zero equipment failures (NRC)
  • Project duration: 2 year 5 months
  • Project came in on time and under budget
  • Commendations received from the Client

Roy Aspden, CNR Decommissioning Manager and a Board Member for Decom North Sea, stated that “Whilst on board, I was very impressed with the NRC set-up. Not only with their equipment packages… but from interacting with their personnel on site, I was instantly reassured by their incredible knowledge of the equipment and walked-through how these cleaning scopes are to be carried out operationally.”

Donald Martin, CNR Contract Sponsor, “Thanks to you and the team for NRC’s contribution to the overall success!! Just goes to show that if you have the right companies working together in the right way you can still hit overall targets… even on massive projects which typically have a long history of cost and schedule overrun.”

Gerry Duffy, Murchison Production Supervisor, “I have worked with the NRC team throughout most of the entire EDC campaign and have found them to be a pleasure to work with. They are, to a man, hard-working, professional, flexible in their approach and very helpful when asked to vary their work-scopes to suit requirements. NRC, as a Company, should be happy to have the quality of work-force these guys have delivered and, on a personal note, they have made my job a lot easier than it could have been.”

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