A significant challenge with a simple goal: transport gas from the Ichthys Field in the Browse Basin to an LNG processing plant in Darwin. To complete the task, plans were put in place for an 882 km, 42 inch (1,067 mm) diameter subsea gas export pipeline laid on the seabed to the landfall and an 8 km, 42 inch diameter onshore pipeline to the LNG plant.
A job with an unprecedented level of moving parts, The Australian Pipeliner speaks to INPEX Offshore Facilities Completion Manager Jarrad Blinco to get a better understanding of how it all came together.
“I acted as Engineering and Construction Manager for the gas export pipeline,” he says.
“I was supported by a team of engineers and construction execution personnel and together we were responsible for all the detailed engineering, procurement, fabrication, construction and installation of the whole pipeline.”
Despite many years of experience in the industry and having worked for INPEX for a number of years prior to the Ichthys LNG Project, Mr Blinco says the size of the development made it stand out in comparison to previous jobs.
“It’s a completely different scale; massive and complex and very challenging. Everything is ten times
larger than most other projects in the industry.
“It’s certainly been very exciting. You get to see a lot of industry firsts and we were always doing things differently and larger.”
Pipes and coating
The project reached its final investment decision in 2012 leading to contracts being awarded for line pipe manufacturing and coating. Suppliers Europipe, Sumitomo Metals and Nippon Steel Corporation began manufacturing the pipes later that year, with coating managed by Bredero Shaw before the pipe was stockpiled at two coating yards in Kabil, Indonesia and Kuantan, Malaysia.
It took a year and a half to manufacture and coat the line pipe, which comprised 74,000 individual 12.2 m joints of pipe made of nearly 685,000 t of steel. Mr Blinco says this was an exceptional feat in itself.
“That was a significant quantity of pipe that we needed,” he says.
“It’s unique because it’s quite heavy wall pipe, about 30 mm thick. There are very few pipe mills in the world that can manufacture the pipe to the required specification and tolerances needed for offshore gas hydrocarbons.
“We eventually went to three different pipe mills and needed all three working concurrently to satisfy the schedule because we were so demanding on their capacity and their own resources.”
Construction commences
After the completion of the pipe manufacturing and coating, construction of the pipeline began in 2014 with dredging and landfall preparation in Darwin Harbour. As with the pipe manufacturing, preparation for the pipelaying campaign presented its own set of unique challenges.
“The main scope for Darwin was the landfall and the shore crossing,” says
Mr Blinco.
“We had to make the area ready to start to haul the pipeline up the shoreline; the overall shore pull was about 2.1 km long.
“One of the challenges we had at the landfall was the topography is quite gentle, which meant we couldn’t get a lay barge close enough to the landfall, or as close to the landfall as was desired. It meant we needed a large winch to pull the pipeline right up the landfall itself.”
It took about a week to winch the pipeline to its correct elevation, after which the shallow water pipelay through Darwin Harbour could begin.
“One of the early risk prevention measures for the pipeline, identified during the design, was to put the pipeline inside a trench with rock armouring over the top, inside Darwin Harbour. This helped to protect against dropped and dragged anchors from LNG vessels and other ships that regularly use the harbour.”
The rock used to protect the pipeline in Darwin Harbour was sourced from two Mount Bundy quarries in the Northern Territory, located about 100 km southeast of Darwin. Approximately 700,000 t of rock was transported from the quarries to the stockpile facility using quad road trains operating 12 hours a day, six days a week.
The shore pull and the 170 km shallow water pipelay was completed by the semi-submersible anchored pipelay barge SEMAC-1 in five months, after which the Saipem vessel Castorone picked up the pipeline end and continued to the field.
Unlike the SEMAC-1, which is a conventional shallow water pipelay barge with double joint technology, Saipem’s ship is equipped with triple joint technology and state-of-the-art pipelay parameter monitoring.
Mr Blinco says the Castorone was perfectly suited for the challenging pipelaying operation, which it eventually completed without issue.
“It was a smooth operation and we achieved some very good pipelay rates,” he says.
“The Castorone is unique because it’s a triple joint vessel, meaning crews can weld three joints of pipe together before they offer it up to the actual pipeline itself and weld it into the pipeline.
“Each joint of pipe is 12.2 m long and on board the vessel it’s welded into triple joints 36 m long, so as you’re laying pipe you’re offering up 36 m long strings. We averaged about 3.2–3.4 km per day, but at maximum we managed to get up to about 4.9 km per day, which was very good effort.”
Prioritising safety
Safety was the number one priority and challenge throughout the pipeline procurement and construction phase.
The were significant quantities of steel and concrete used and a high number of pipe movements. To mitigate manual handling risks, automated pipeline handling was implemented throughout the supply chain from pipe manufacture through to offshore installation.
“Overall, 2.3 million safe pipe lifts were achieved with no injuries to personnel or major incident events,” says Mr Blinco.
“You’re dealing with such large components and dealing with so much of it, many different people, contractors and areas of work, it’s very important to safely and effectively manage all facets. That was definitely the biggest challenge and it takes a lot of work to get through the construction and procurement phase.”
At the end of such an enormous, time-consuming and challenging task, with such an intense focus on safety, Mr Blinco said he was happy with the final result.
“You obviously feel very proud in the work you’ve done, because it’s such a large undertaking,” he says.
“There’s also a lot of satisfaction to get to the end of the project safely and get there having delivered a quality product.”
For more information visit the Inpex website.
This article was featured in the February 2019 edition of The Australian Pipeliner. To view the magazine on your PC, Mac, tablet, or mobile device, click here.
If you have a project you would like featured in The Australian Pipeliner contact Managing Editor David Convery at dconvery@gs-press.com.au
