Gas on the North West Shelf

Western Australia, as Australia’s number one petroleum producer relies heavily on gas fields in the North West Shelf for both its domestic and export industries.

While Western Australia already relies heavily on the North West Shelf (NWS) for its gas needs through gas produced from the North West Shelf Venture (NWSV), a number of further gas developments in the region have been planned for the resource rich area, such as Woodside Petroleum’s Pluto Gas Project, Chevron’s Gorgon and Wheatstone developments and Apache Energy’s Reindeer and Julimar fields.

These additional projects will strive to meet the ever increasing demand of the state.

Demand for domestic gas in Western Australia is predicted to increase by 1,125 terra joules per day (TJ/d) by 2014, a DomGas Alliance report has said. The average rate of increase in gas consumption in the state since 1984 has been recorded at 8.5 per cent per year.

NWSV: the gas powerhouse

The NWSV project, after almost 25 years of pipeline gas production, remains Australia’s largest natural resource development. Nor is there any sign of slowing with only 11 trillion cubic feet (Tcf) of the NWSV’s vast 33 Tcf total gas reserves produced to date.

The NWSV supplies gas for Western Australia’s domestic market, providing approximately 65 per cent of the state’s total production. It also supplies gas for export sourced from its offshore gas fields.

Since delivering its first LNG cargoes to Japan in 1989, the $25 billion NWS project now ships more than 200 cargoes a year to countries such as China, Japan and South Korea.

NWSV natural gas, LNG, liquid petroleum gas and condensate is processed at the Woodside-operated onshore Karratha Gas Plant, located 1,260 kilometres north of Perth. The plant has now produced more than 1,000 cargoes of condensate.

Last year the NWSV celebrated the completion of its $2.6 billion Phase V LNG Expansion Project. The expansion included a fifth LNG processing train – capable of producing up to 4.4 million tonnes per annum (MMt/a) – a jetty extension and second LNG loading berth, two additional power generation units, a third fractionation unit, a new fuel gas compressor, an acid gas removal unit and a third boil-off gas compressor.

NWSV: North Rankin

When commissioned in 1984, North Rankin A was the largest gas production platform in the world, capable of producing 1,815 million cubic feet of gas per day (MMcf/d) and up to 47,400 barrels per day (bbl/d) of condensate. Subsequent modifications have increased this capacity by 50 per cent.

In 2008, the NWSV announced the North Ranking redevelopment project, which will provide additional compression to unlock low pressure reserves from the North Rankin and Perseus gas and condensate fields.

The platform will be connected by a 100 metre bridge to the existing North Rankin A platform. Known as the NR2 Project, it will also include necessary tie-ins and refurbishment of North Rankin A. Upon completion, both platforms will be operated as a single integrated facility.

NWSV: Angel Gas Field

The NWSV’s Angel Platform became operational in October 2008, producing gas for processing at the venture’s Karratha Gas Plant.

The $1.6 billion development involved the installation of a new platform and associated infrastructure, including a 50 km subsea pipeline tied back to the existing North Rankin A platform. The Angel Platform is powered and remotely controlled from the North Rankin A Platform via a subsea cable.

Located approximately 120 km northwest of Karratha, the Angel Platform stands in about 80 metres of water and is supplied by three subsea production wells. With a production capacity of 800 MMcf of raw gas and up to 50,000 bbl/d of condensate, hydrocarbons from the Angel platform will be processed through the NWSV’s integrated system.

Reindeer Gas Field

The Reindeer field was discovered in 1997 and has a gross recoverable resource range of 410–640 PJ.

Apache Energy and Santos are progressing the development of the field, located in WA-209-P, approximately 80 km off the Port of Dampier. Gas and liquids from the field will be exported from an unmanned wellhead platform to the proposed $260 million Devil Creek Gas Plant via a 105 km pipeline.

The Devil Creek Gas Plant will connect into the Dampier to Bunbury Natural Gas Pipeline. The proposed production capacity is approximately 110 TJ/d of sales gas with first gas targeted for mid-2010. The Reindeer field is set to supply CITIC Pacific’s Sino Iron project in Western Australia.

Pluto Gas Project

The Pluto Gas Project, located approximately 190 km northwest of Karratha, has a dry recoverable volume estimate of 5 Tcf and will be developed via two LNG trains. 

The project, which is being undertaken by a joint venture between Woodside, the Kansai Electric Power Company and Tokyo Gas Company, involves developing gas from the Pluto and Xena fields and transporting it through a sub-sea 180 km, 36 inch diameter pipeline to an LNG plant where it will be used for domestic gas supply as well as being liquefied and shipped to customers in Japan.

The first 14 modules and supporting structures for the first LNG train have arrived on site. Jumbo was contracted to ship a total of 143 pre-assembled modules from Laem Chabang, Thailand, to the onshore LNG production system in Dampier over the course of 26 voyages.

Gorgon and Wheatstone developments

The Gorgon LNG Development is a joint venture between Chevron, Shell, and ExxonMobil, and is located approximately 130 km off the northwest coast of Western Australia.

The development involves the installation of a subsea gathering system and pipelines from the Gorgon and Jansz fields to Barrow Island. A 300 TJ/d gas processing facility, located on the central-east coast of Barrow Island, will then process the gas and reservoir carbon dioxide will be removed and re-injected into deep saline reservoirs beneath the island. The LNG will then be shipped to international markets while the compressed domestic gas will be delivered to the Western Australian mainland via subsea pipeline.

In September 2008 the joint venture extended the front-end engineering and design contract to a joint venture comprising KBR, JGC Corporation, Clough Projects Australia and Hatch Associates Group to incorporate a third 5 MMt/a LNG train to be developed in conjunction with the first two trains.

Chevron has also announced plans to develop an LNG project, based on its Wheatstone natural gas discovery, located 145 km offshore in the Carnarvon Basin.

The facility will be located on the Pilbara coast and will have an initial capacity of at least two 5 MMt/a LNG production trains with expansion capacity for an additional three production trains. The development will also include a 250 MMcf/d domestic gas plant that will form part of the development and a 220 km pipeline.

Karratha Power Station

In November 2008, Horizon Power entered into an agreement with Canadian energy company ATCO Power to build a gas-fired power station at Karratha to link into the North West Interconnected System (NWIS).

The 86 MW power station, to be situated adjacent to Horizon Power’s 132 kilovolt (kV) Karratha substation, could be expanded to a total generation capacity of 150 MW. The project is due to be completed by March 2010.

The plant will initially comprise two high-efficiency gas turbines and could grow to include a heat recovery steam generator that will produce electricity from waste heat.

Getting connected

The Dampier to Bunbury Natural Gas Pipeline (DBNGP) supplies 90 per cent of the southwest’s gas needs. The pipeline is a key piece of infrastructure linking the NWS with industrial, commercial and residential customers in Perth and the surrounding region.

The State Energy Commission of Western Australia commenced construction in 1983 with more than 1,500 km completed by 1984. In order to satisfy Western Australia’s growing energy needs the pipeline has continued to expand through looping and compression. The pipeline, now owned by Dampier Bunbury Pipeline (DBP), extends from the Burrup Peninsula near Dampier, to Bunbury in the southwest of the state.

In addition, a 104 km subsea pipeline was constructed in tandem with the DBNGP as part of the North West Shelf development to connect the North Rankin A platform to Dampier. Complete in 1983, the pipeline transports North West Shelf gas to shore.

Currently, the pipeline is being expanded through the $700 million Stage 5B looping project The bulk of the Stage 5B expansion work involves laying an additional eleven sections of pipeline looping totalling 440 km, which, when completed, will result in the DBNGP system over 75 per cent duplicated. The expansion will add approximately 112 TJ/d to the existing full haul capacity of the DBNGP.

Gas projects in the pipeline

Looking to the future of gas infrastructure, Western Australian Premier Colin Barnett has put his support behind the development of a trans-continental pipeline, to run from the NSW to eastern Australia.

The proposal for the pipeline, which would stretch across Australia, linking the nation’s gas infrastructure by connecting the NWS gas hub to the Moomba gas hub in South Australia, has been explored at various times in the past.

However it is uncertain whether this project will go ahead. Western Australia is known to be a large consumer of gas due to general economic expansion, as well as exporting large quantities of gas overseas. Because of this, the Chamber of Minerals and Energy Western Australia has noted that, in the longer term, the state must find a balance between ensuring security of energy supply to meet the ongoing needs of the state’s economy, while also facilitating growth in energy exports.

Whether or not the pipeline goes ahead, with the gas-rich NWS, it is clear that the projects currently under development in the area will serve to aid the state’s gas supply and export capability.

The NWSV is a joint venture project between Woodside Petroleum, BHP Billiton, BP Developments Australia, Chevron Australia, Japan Australia LNG and Shell Development.

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