Subsea Infrastructure Removal of Bains Well Head Protection Structure (WHPS)

Client: Spirit Energy

Contractor: Oceanic Vessel

Service Provider: NMC Energy

Project: Subsea Infrastructure Removal of Bains Well Head Protection Structure (WHPS)

Location: Offshore, Shallow Water Area

NMC Energy was tasked with the management of the subsea infrastructure removal, specifically focusing on the Bains Well Head Protection Structure (WHPS), weighing approximately 115 tons (with a 47-ton contingency). The removal process involved a reverse installation method, utilizing suction cans to lift the structure out of the seabed in a controlled manner. NMC Energy managed all aspects of the project, from engineering checks and factory acceptance tests (FATs) to offshore operational readiness, including oversight of the 500m safety zone and client representation offshore.

NMC Energy’s involvement in the Bains WHPS removal covered various critical aspects:

Package Management and Engineering Checks:

• NMC Energy provided comprehensive package management, ensuring that all engineering and operational readiness activities were completed to the highest standards.
• The team conducted detailed engineering checks to assess the structural integrity of the WHPS and subsea infrastructure, preparing for the removal phase.

Operational Readiness and FATs:

• Before offshore execution, NMC Energy supervised Factory Acceptance Tests (FATs) to ensure that all equipment and procedures were fully operational and compliant with the project’s requirements.
• Operational readiness was a priority, with NMC Energy ensuring that all stakeholders, including contractors and subcontractors, were aligned on the removal strategy and prepared for any contingencies.

Management of 500m Offshore Safety Zone:

• NMC Energy managed the 500-meter safety zone around the removal site to ensure the safety of personnel and equipment during the subsea removal operations. This included securing the zone from unauthorized vessels and managing navigational hazards.

Client Representation Offshore:

• NMC Energy provided client representatives onboard the Oceanic vessel to oversee the removal of the WHPS and subsea infrastructure. This ensured real-time oversight, problem-solving, and communication with onshore teams.

Controlled Removal via Reverse Installation Method:

• The WHPS removal used a reverse installation method for a controlled and safe extraction. Four suction cans were pumped out of the soil before the structure was lifted from the seabed by the Oceanic vessel.
• This method minimized risk and maintained stability throughout the process, ensuring no damage to surrounding infrastructure or the marine environment.

Removal of Additional Subsea Infrastructure:

• NMC Energy also managed the removal of associated subsea infrastructure, including pipeline sections, mattresses, umbilicals, and grout bags. Each component required careful planning to prevent environmental impact and ensure compliance with regulatory standards.

High Current:

• The removal area experienced strong underwater currents, posing a challenge to both the stability of the WHPS and the safe operation of lifting equipment. NMC Energy developed strategies to mitigate these risks, including precise timing of operations to avoid peak current periods and utilizing specialized equipment to secure the WHPS during lifting.

Shallow Water:

• The shallow water environment added complexity to the removal operation, requiring careful planning to ensure that vessels and lifting equipment could operate effectively without risking damage to the infrastructure or marine ecosystems.

Poor Visibility:

• Limited underwater visibility was another challenge during the removal of the WHPS and subsea infrastructure. NMC Energy employed advanced sonar and remote-operated vehicles (ROVs) to provide accurate positioning and ensure safe and controlled operations despite the visibility constraints.

• Safe and Controlled Removal: Despite the challenges of high currents, shallow waters, and poor visibility, NMC Energy successfully managed the safe removal of the Bains Well Head Protection Structure. The reverse installation method allowed for a controlled lifting process, ensuring minimal disturbance to the seabed and surrounding environment.
• Effective Offshore Coordination: NMC Energy’s client representatives aboard the Oceanic vessel ensured effective communication and coordination with both offshore and onshore teams. This real-time oversight allowed for swift decision-making and risk mitigation during operations.
• Successful Removal of Subsea Infrastructure: In addition to the WHPS, NMC Energy successfully managed the removal of pipeline sections, mattresses, umbilicals, and grout bags, ensuring that all subsea infrastructure was safely extracted and prepared for disposal.
• Management of Safety and Environmental Risks: NMC Energy’s management of the 500m safety zone, coupled with its emphasis on HSE standards, ensured that the project was completed without safety incidents or environmental damage. The use of ROVs and sonar systems mitigated risks associated with poor visibility, further enhancing operational safety.

NMC Energy’s management of the subsea infrastructure removal, including the Bains Well Head Protection Structure, demonstrates its ability to handle complex offshore projects in challenging conditions. Through comprehensive package management, effective safety zone oversight, and innovative removal techniques, NMC Energy delivered a successful project while maintaining strict adherence to safety and environmental standards. This case study highlights NMC Energy’s expertise in subsea decommissioning and its capacity to deliver results under challenging conditions.