The Woodside North Rankin Alpha platform illustrating the derrick structure being decommissioned by Vertech rope access tradesman

North Rankin Derrick Decommissioning

Vertech was engaged in decommissioning the North Rankin Derrick, a drilling derrick on an offshore production platform whilst the platform was operational. Vertech provided planning, engineering and technical services, completed onshore mock-up trials, and managed multi-disciplinary rope access personnel to complete this challenging project successfully.

Project Planning

The Vertech project management team worked closely with engineers and management teams from Transfield Worley and Alliance Engineering (AEC) to review every phase of the project execution.  Site team deployed to complete NDT inspections, electrical inspections, UAV surveys as well as visual and dimensional surveys.  Over a 6-month period this careful and meticulous planning and collaboration between each contractor reaped significant benefits as we identified areas of challenge that we could engineer out, identify areas where specialist tooling or specialist access systems would add for greater efficiency and safety performance and ultimately model and sequence each lift.

On completion of the project planning phase a comprehensive mock up trial with all IRATA supervisors, rope access tradesmen who would mobilise was conducted using the HIAB mounted crane to familiarise the teams with each piece of equipment and to simulate the scenario offshore. This level of pre planning and training was a significant factor in the safe and successful completion of this project.

Solution and Results

The North Rankin Alpha (NRA) Platform derrick being decommissioned by vertech rope access tradesmen. This image illustrates the dual crane lift.

In the practical delivery, Vertech provided technical rigging solutions utilising a Hi-Ab crane mounted on the derrick guide rails, as well as welding and cutting, fitting, and electrical trade services. The engagement of a multi-skilled and highly motivated team was crucial in the successful deconstruction of the derrick allowing for 20 multi-skilled personnel to replace the proposed 41-man implementation crew.

We worked closely with key contractors such as alliance engineering and Transfield Worley to plan and sequence every component of the project from the initial deconstruction and removal of all tertiary steel, electrical cabling and ancillary equipment moving onto stick deconstruct using a custom Hi-Ab crane and finally to modular lifts and dual crane lifts all while the facility was still in full production

The project was completed with a perfect safety record and included many innovations to allow effective delivery.

Woodside Energy - North Rankin Drill Derick Decommissioning

The top portion of the derrick being removed by 2 cranes.

Vertech Group - North Rankin Derrick Decommissioning

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Vertech technicians work on decommissioning a derrick.
NRA Derrick Destruct Case Study