Overview
AGIG signed an agreement with Chevron to build, own and operate the domestic The Wheatstone Ashburton West Pipeline (WAWP) in September 2013. The 110km long WAWP links the Wheatstone domestic gas plant to the Dampier Bunbury Natural Gas Pipeline (DBNGP). The main 16-inch pipeline is named as two parts – the Wheatstone Lateral and the Ashburton West Loop. Connecting and running parallel to the Ashburton West Loop is the 10-inch, 87 km long Ashburton West Lateral.
The project included:
• Refurbishment of AGIG’s existing 87 kilometres 10-inch pipeline from Ashburton West to Compressor Station 2 on the DBNGP
• Construction of an 87km, 16-inch pipeline (loop) alongside the existing 10-inch pipeline
• Construction of a new 22km, 16-inch pipeline, connecting Ashburton West to the Wheatstone domestic gas plant
• An initial 30-year 100% take-or-pay gas transportation contract between AGIG and Chevron – the project will provide an initial forward haul gas transmission capacity of 337 TJ per day with future expansion capacity of up to 600TJ per day.
Project Overview
In September 2017, we began commercial operations of Tubridgi for Citic. This is located 25km west of Onslow in very close proximity to the Chevron operated Wheatstone gas plant and BHP operated Macedon gas plant, and adjacent to the Ashburton West facilities. Tubridgi is 100% owned and operated by AGIG, and serves all the state’s major gas consumers and producers via a pipeline network that connects Tubridgi to the Dampier Bunbury Natural Gas Pipeline (DBNGP).
Survey of pipeline route
Part of the project Front End Engineering Design (FEED) studies included walking the pipeline route to de-risk the construction process. The survey was completed in consultation with traditional owners and pastoral land owners in a constructive manner to minimise disruption and impact. The line pipe was sourced from Japan, supplied by Metal One Corporation and delivered to Dampier Port in early April in line with the construction schedule.
Technical approvals
The pipeline licence application process was managed with the Department of Mines, Industry Regulation and Safety using in-house expertise. Subsequent approval stages involved consent to construct, operate and commission, also managed through the same technical approvals team. Other key approvals included the development of a Safety Case acceptable to the regulators.
Operation
Post construction, the commissioning team mobilised. The same process was followed as the Fortescue River Gas Pipeline, including all mechanical and electrical checks of safety valves, metering systems and the Supervisory Control And Data Acquisition (SCADA) remote communications. Once signed off and regulatory approval granted, the pipeline was purged with nitrogen to remove the air in the line before introducing natural gas. The system pressure was incrementally increased with system checks at each megapascal (MPa) of pressure.
Once the pipeline passed all commissioning checks, the system was handed over to operations in the electronic asset management system. This ensured the Asset Management Plan and associated processes developed by the in-house technical and operations teams were functional for operations. Based on these processes, the operations team will undertake preventative and corrective maintenance for the entire life of the pipeline.
Practical completion
In December 2014, AGIG reached practical completion of the Wheatstone Ashburton West Pipeline, and in March 2019, Wheatstone domestic gas deliveries began operations.
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