Santos GLNG has achieved another milestone, with the final section of its gas transmission pipeline successfully pushed through a tunnel beneath the Gladstone Harbour to the LNG plant on Curtis Island.
The 120 pipeline segments, each measuring 36 metres in length, were welded and pushed gradually through the 4.3-kilometre tunnel over the past month using a large hydraulic jack. The tunnel was filled with seawater to buoy the 42-inch diameter pipeline as it was pushed through.
Santos Vice President Downstream GLNG Rod Duke said the delivery of the first under-sea crossing for Queensland’s CSG-to-LNG industry “brings our pipeline to its final stages of completion and demonstrates our ability to deliver world-class projects and operations.”
“This year is about delivering milestones across Santos GLNG, and we’re particularly proud of this achievement given the innovation and expertise required to achieve a marine crossing like this one,” Mr Duke said.
“Our under-sea tunnel has allowed us to cross The Narrows without disturbing the local marine environment and with minimal impact to the surrounding coastal environments.
“In the coming weeks the marine crossing pipe will be connected to the rest of Santos GLNG’s 420-kilometre pipeline already buried on the mainland and Curtis Island.”
Pipeline pre-commissioning works are well underway, with clean and gauge activities nearing completion and about half of the required hydrotesting completed. The pipeline route will be fully rehabilitated with initial reinstatement works now more than 90 percent complete.
The gas transmission pipeline is being built by Santos GLNG’s contractor Saipem Australia, while the tunnel was constructed by subcontractor Thiess.
The 3.45-metre internal diameter under-sea tunnel was a feat in itself, running approximately eight metres below the sea bed and constructed using a 100-metre long, 277-tonne tunnel boring machine. Santos GLNG is a pioneering joint venture between Santos, Petronas, Total and Kogas to supply liquefied natural gas to global markets.
Press Release, May 14, 2014; Image: Santos GLNG