Project Profile - Wandoo B Concrete Gravity Structure, GHD & Vermilion Oil and Gas Australia
Project Profile - Wandoo B Concrete Gravity Structure, GHD & Vermilion Oil and Gas Australia14 Nov 2017

This year we received a range of technology and innovation projects entered into our Awards for Excellence Program, each pushing the boundaries of concrete. The 13 project entries that were entered demonstrated innovation in its finest form - exploring theory, materials, processes, systems and technology that has the capability to transform the industry.














There could only be one Medallion for Excellence Winner of this category, and the Institute was very pleased to award this to GHD and Vermilion Oil and Gas Australia for their innovative project - Condition Investigation, Remaining Life Assessment and Inspection Maintenance and Repair Plan for Wandoo B Concrete Gravity Structure.















Vermilion Oil & Gas oil production in the Western Australian North west shelf, 75 kms offshore from Karratha, relies on the Wandoo B Concrete Gravity Structure (CGS) to structurally support its oil facilities and provide oil storage.















The CGS original operational life was 20 years (from 1997) and an extension of 20 years was required. The exposure condition is aggressive offshore marine. Inspection and testing of concrete was challenging and key constraints for an operational offshore oil platform above water included limited accessibility to surfaces, maintaining site operations during survey works, working at heights and over water with safety as a priority. Inspections below water were conducted using Remotely Operated Vehicles (ROV), where sea level tides and currents provided significant challenges during inspection.













GHD was engaged as the concrete engineering consultant to complete the CGS condition investigation and remaining life assessment including provision of an inspection, maintenance and repair (IMR) plan. Third party verification was by Lloyds Register. The CGS has seabed oil storage caissons 115 m long, 70 m wide and 17 m high and four shafts 10 m internal diameter to 69 m high. Design uses reinforcement and prestress tendons. Concrete was grade 50 MPa with 65% blast furnace slag.















The remaining life assessment determined a 20 year life extension can be achieved. A service life of 60+ years can reasonably be achieved with specific life primarily dependent on atmospheric concrete chloride ingress risk and following the IMR Plan first-time developed for the Wandoo B CGS. The judges noted that this innovation and technology was ground-breaking, and could have massive implications worldwide for the industry.

The Institute is already looking forward to the technology and innovation projects entered in our 2019 program!