The Gorgon Project’s subsea gas gathering system is the largest ever installed in Australia. Operated from the Central Control Room on Barrow Island through subsea umbilicals, the production system is located on the ocean floor at the Gorgon and Jansz-Io gas fields.
The Jansz-Io field is located approximately 130 kilometres northwest of Barrow Island in 1,350 metres of water and will be brought onstream first. The initial subsea development is a ten well, two manifold system. The Gorgon field is located approximately 65 kilometres to the west of Barrow Island in 200 metres of water. The initial subsea development is an eight well, three manifold system. The produced gas from the wells will be gathered at several manifolds installed at each field, then transported via pipelines to Barrow Island.
All 20 main structures have been installed - some weighing in excess of 1,000 tonnes and with footprints the size of a city office building. The structures were positioned within a five metre target circle, some in water depths up to 1,350 metres using specifically developed deep water lowering system.
The structures and pipelines are connected by 63 tie-in spool pieces. Once measurements were taken between the structures and the pipelines subsea, fabrication of the spools occured onshore. The subsea measurements were critical, with an accuracy of within a mere 50 millimetres which was a challenging task given some of the spools were in excess of 100 metres long. Due to the size and complex configuration of these spools, truss-tope spreader frames were specially built to ensure the integrity of the spool piece during lifting onshore and deployment offshore.
Subsea trees, installed at each of the fields, contain and control the production wells.
All subsea connections are completed by remote operated vehicles eliminating all diver operations.