Gas contributes up to 50 per cent of Western Australia’s primary energy use and fuels up to 60per cent of the state’s electricity generation capacity. The DBNGP is the only natural gas pipeline connecting the Carnarvon Basin on Western Australia’s North West Shelf with Perth and the surrounding region, supplying 90 per cent of the demand for gas in the south west of Western Australia.

It comes as no surprise then that pipeline owner Dampier Bunbury Pipeline (DBP) has expanded the pipeline’s capacity twice since it acquired the pipeline in 2004 and has recently obtained necessary financing and equity commitments for an additional expansion.

DBP bought the pipeline from Epic Energy in October 2004, who had previously purchased the pipeline from the state government in 1998. Since taking ownership, DBP has made expansion of the DBNGP a key focus of the company, committing a total of $1.8 billion to expanding the pipeline’s gas haulage capacity to meet Western Australia’s growing demand. This equates to 125 per cent of the regulated value of the pipeline as at 2005.

Successful construction for Stage 5A

In May 2005, the DBP board approved a $430 million expansion program – known as the Stage 4 Expansion – comprising eight new compressors and over 200 km of looping. This expansion increased the pipeline’s capacity by over 100 terajoules per day (TJ/d) and was completed on time and within budget in February 2007.

Before the Stage 4 Expansion was complete, DBP announced plans for a further expansion known as Stage 5, which includes an additional 1,150 km of new pipeline looping and the installation of one 7 megawatt (MW) and a further four 10 MW compressors.

The first component, Stage 5A, commenced construction in late February 2007. It comprised 10 loops constructed by Saipem, with a total length of 570 km, adding approximately 90 TJ/d of full haul capacity to the DBNGP. A total of 700 people worked on the expansion, with 650 located on site. Major contractors for the project included Saipem and Enerflex for the construction of compressor stations. WorleyParsons provided engineering, design and project services personnel, OSD Pipelines provided key pipeline expertise and PCT supplied project regulation and engineering expertise.

All contractors adhered to a Zero Harm approach to both safety and the environment, which saw operations comply with, and often exceed, the requirements of all relevant regulations and standards.

DBP Executive Chairman Stuart Hohnen said “The Stage 5A Expansion was delivered on time and on budget in a climate where many projects of this scale suffer delays and cost over runs.”

He added that the completion of Stage 5A was a considerable achievement on the part of all concerned, including project manager WestNet Energy, a division of Alinta Asset Management.

The project also required major community and stakeholder consultation, with over 300 individuals or representative bodies engaged in the consultation process to ensure the project’s success. In total, the project required liaising with 280 landowners, 16 Shires, 3 Regional Divisions of Main Roads WA, 6 Regional Divisions of DPI, 10 other Government Departments, State Ministers and local members of parliament.

The pipeline’s proximity to homes, parks and playgrounds also meant a great deal of engineering analysis was required to ensure community safety.

The Stage 5A expansion also involved negotiating some key challenges. These included major river crossings – including the Robe, Yannarie, Minilya and the Murchison – dune crossings, and confirming that the pipeline route was safe for construction and trenching through historical military ranges. An investigation was conducted that confirmed that over 60 km of pipeline easement was free from unexploded bombs and devices left over from 40-plus years of military target practice.

Stage 5B in the pipeline

The second Stage 5 component – Stage 5B – will involve a further 440 km of looping and some additional compressor station modifications, with an estimated cost of $690 million. Construction is expected to commence in early 2009, with commissioning of the final tranche of the additional capacity due to occur in the second half of 2010.

Stage 5B represents further capacity requirements of approximately 110 TJ/d of firm full haul capacity and 140 TJ/d of part haul capacity in addition to the recently completed Stage 5A expansion.

Currently, work is well advanced on project engineering, approvals and procurement for Stage 5B. Line pipe is expected to be delivered in December. Final pipelaying tenders are being assessed, with a final decision to be made during the first half of September.

All necessary financing has been obtained for the project and contracts with shippers for the additional capacity to be delivered from 2010 have been executed.

DBP Executive Chairman Stuart Hohnen said that the decision to increase the Stage 5B expansion came after receiving additional firm capacity requests from existing and prospective shippers.

DBNGP: best option for WA

Following a pipeline rupture that occurred at Apache Energy’s Varanus Island facilities in June 2008 and cut Western Australia’s gas supply by 30 per cent, there was speculation about the need for a second major gas pipeline in the state. However, arguments against this take into account the production challenges that Western Australia faces in regards to the supply of natural gas, as well as the ability for the DBNGP system to continue to expand through the progressive addition of further looping and compression.

The Stage 4 and 5 expansions will effectively duplicate approximately 90 per cent of the length of the DBNGP. DBP said that this is a much faster and more cost effective approach to the delivery of new capacity than the construction of a second pipeline system, which the company said would be heavily underutilised for many years – at high cost to users.

The completed DBNGP expansion programs suggest that it is possible to engineer, finance and build new capacity in a shorter period of time than it takes to build new processing plants or power stations.

“It could be said that the pipeline is the backbone of the booming Western Australian economy, the key to ongoing prosperity in this state. However, we are functioning in a gas constrained environment and new supply is critical,” Mr Hohnen said.