Innovation with the Ichthys offshore pipeline

Once completed, the 889 km, 48 inch diameter pipeline will be the longest subsea pipeline in the southern hemisphere. It will transport gas from the Ichthys Gas Field, located in permit WA-37-R in the Browse Basin, approximately 200 km offshore northwest Australia, to an onshore LNG processing facility located at Blaydin Point, Darwin.

Before leaving the gas field, the gas will undergo preliminary processing at the offshore central processing facility (CPF) to remove water and raw liquids, including a large proportion of the condensate. This condensate will be pumped to a floating production, storage, and offloading (FPSO) facility anchored nearby, from which it will be transferred to tankers for export.

Estimated reserves for the project stand at over 12 Tcf of gas and around 500 MMbbl of condensate. The project is initially expected to produce 8.4 MMt/a of LNG from two trains, 1.6 MMt/a of LPG and 100,000 bbl/d of condensate at peak. The facilities will include two 165,000 cubic metre LNG storage tanks.

The Ichthys LNG Project equity interest is INPEX (operator, 66.070 per cent), Total (30 per cent), Tokyo Gas (1.575 per cent), Osaka Gas (1.2 per cent), Chubu Electric Power (0.735 per cent), and Toho Gas (0.42 per cent).

Saipem has been awarded the pipe-lay contract for the offshore pipeline, following-on from initial front-end engineering and design works undertaken by JP Kenny and AMEC. Boskalis is also subcontracted to Saipem to assist with associated pipeline works.

To catch up on the where the pipeline’s construction is at, Pipelines International spoke with INPEX General Manager External Affairs and Joint Venture Bill Townsend, who provided an update.

At what engineering phase is the subsea pipeline currently?

The entire linepipe has been produced and coated. Pipe laying is scheduled to begin in the middle of the year.

How many people does Saipem have currently working on the contract, and what is Saipem using to undertake the pipe lay?

Saipem has a team of approximately 50 people in its Perth office and has support for the engineering team from the Saipem offices in London, Fano (Italy), Singapore, and Rijeka (Croatia).

The newly-built Castorone fourth-generation pipe-lay vessel and the Semac-1 pipe-lay barge will be used for the shore pull and the shallow sections near Darwin, respectively.

Will INPEX be using any particular innovations for the installation?

The Castorone itself is a main innovation introduced to the Ichthys Project. Approximately 600 people will work on this vessel assembling on-board triple joints.

The Castorone is a unique vessel in that it will pre-assemble (weld) triple-joints inside the vessel before the triple-joint string is moved into the firing line for assembling into the main pipeline.

How will the offshore pipeline be stabilised?

Concrete coating is the primary means of stabilisation. Trenching and rock cover is also used within Darwin Harbour to protect the pipe.

Whereabouts is the pipe lay beginning and where will be the final stage of the pipe lay?

The installation starts at the Darwin end with pipe-lay progressing towards to Ichthys Field.

Firstly, a shore pull will be undertaken by the Semac-1 in Darwin Harbour, approximately 2 km north of Channel Island, to pull the pipeline on to land. The Semac-1 will then pull away and lay approximately 130 km of the pipeline.

The Castorone will then be used as the main pipe-lay vessel to lay the remaining 760 km of pipeline to the Ichthys Gas Field.

What other contractors are involved in the offshore pipe lay?

Boskalis is the main subcontractor to Saipem and is responsible for all pipeline dredging, shore crossing civil construction, rock quarrying, and rock installation onto the pipeline.

How are the onshore facilities progressing, and when does INPEX anticipate that the pipeline will reach the onshore facility?

Construction of the onshore facilities is progressing well. Site clearance is complete and civil works well advanced at the LNG facilities site at Blaydin Point, Darwin.

The Darwin Harbour dredging is nearly completed and the pipe lay is due to be completed in early 2016.

Will there be any tie-backs, spools, or additional flowlines associated with the offshore pipeline? And what onshore pipeline will there be, if any?

Yes. There are other pipelines associated with the Ichthys Project, including corrosion-resistant-alloy (CRA) flowlines and mono-ethylene glycol (MEG) pipelines which are located offshore at the Ichthys Gas-Condensate Field, as well as onshore pipelines.

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