Wheatstone/Iago

Location and Geology

The Wheatstone and Iago gas fields are situated in the Northern Carnarvon Basin, approximately 100km north of Barrow Island and 225km north of Onslow. The fields are located within the exploration permits WA-253-P, WA-17-R, and WA-16-R.

Project Overview

The Wheatstone Project is operated by Chevron and is one of Australia's largest resource developments. It is designed to process gas from the Wheatstone, Iago, Julimar, and Brunello fields. The project involves the development of these fields through a subsea gas gathering system tied back to the Wheatstone Platform, which is connected to an onshore LNG facility via a trunkline.

Ownership and Partners

The project is a joint venture between several companies:

• Chevron (operator) - 64.1%
• Kuwait Foreign Petroleum Exploration Company (KUFPEC) - 13.4%
• Woodside Energy Group Ltd - 13%
• Kyushu Electric Power Company - 1.46%
• PE Wheatstone Pty Ltd, part-owned by JERA (formerly TEPCO) - 8%.

Infrastructure

Offshore Platform

The offshore processing platform is located in approximately 70 meters of water, about 225km from the coast. It is one of Australia's largest offshore facilities, with the topsides weighing around 36,000 to 37,000 tonnes. The platform receives gas and condensate from the various fields, which are then dehydrated, compressed, and transferred via a 225km subsea trunkline to the onshore gas plant.

Subsea System

The subsea manifolds are located at depths ranging between 100m and 260m, with subsea trees clustered around them. The development wells are drilled from these subsea trees to a depth of about 3km. The wells are tied back to the processing platform using a network of corrosion-resistant subsea pipelines.

Trunkline

The 225km-long trunkline, which is the largest diameter gas pipeline in Australia (1,120mm), transports gas from the offshore platform to the onshore facilities. It crosses the shore using a micro-tunnelling technique to minimize environmental impact.

Onshore Facilities

The onshore gas plant is located 12km west of Onslow at the Ashburton North Strategic Industrial Area. The plant includes two LNG trains with a combined capacity of 8.9 million tonnes per annum (Mtpa) and a domestic gas plant. The domestic gas plant has a capacity of 200 terajoules per day and supplies gas to the Dampier Bunbury Natural Gas Pipeline.

Development and Production

• Discovery and Development: The Iago field was discovered in 2000, with an extension discovered in 2008. Chevron discovered the Wheatstone offshore gas resource in 2004.
• Final Investment Decision: The decision to proceed with the project was made in September 2011, with construction starting in December 2011.
• First Production: The first shipment of LNG was announced in October 2017. LNG Train 1 and Train 2 commenced production in October 2017 and June 2018, respectively. Commercial production of domestic gas began in March 2019.

Technical Details

• Drilling Campaigns: The fields will be developed through four drilling campaigns over 15 years, with the first phase including nine wells drilled from three subsea manifolds. A total of 23 production wells will be drilled, with the Wheatstone field having four manifolds and the Iago field having two manifolds.
• Platform and Trunkline: The platform's topsides have a total deck area of 20,000m², including primary processing equipment and facilities. The trunkline weighs approximately 200,000 tonnes.

Economic and Community Impact

The Wheatstone Project has significant economic and social benefits:

• Contracts and Local Spending: Billions of dollars in contracts have been awarded to Australian companies, with over $455 million spent with local Onslow businesses and organizations since construction began.
• Community Investments: Chevron and the joint venture participants have invested more than $250 million in social and critical infrastructure projects in Onslow, including upgrades to the airport, health services, roads, recreation facilities, and utilities.
• Employment and Revenue: The project provides employment opportunities, government revenue, and local business opportunities, contributing to the economic development of the region.

Environmental Considerations

The project incorporates several measures to minimize environmental impact, such as using micro-tunnelling techniques for the trunkline to cross the shore and careful planning for the installation of subsea infrastructure.