Not only is the Gorgon LNG Development, located offshore Western Australia, one of Australia’s largest natural gas projects – it has also come to represent industry best practice in environmental management. Gas Today takes a look at how the Gorgon joint venture partners have successfully mitigated the project’s impact on its surrounding environment.
Barrow Island, the site for the majority of activities and development associated with the Gorgon LNG Development, is an internationally significant nature reserve. The Gorgon joint venture partners have recognised the importance of Barrow Island’s conservation, and have taken considered steps toward its preservation.
The scope of the project
The Gorgon LNG Development involves a network of offshore gas drilling and subsea gathering pipelines, and onshore processing plants. Three 5 million tonne per annum (MMt/a) LNG trains, to be located on the centraleast coast of Barrow Island, will process natural gas from offshore wells. Reservoir CO2 will be removed and re-injected into deep saline reservoirs beneath the island. LNG will then be shipped to international markets, while compressed domestic gas will be delivered via a 90 km long, 508 mm diameter subsea pipeline to the WA mainland, interconnecting with the Dampier to Bunbury Natural Gas Pipeline.
Joint venture partners are Chevron Australia as operator, ExxonMobil, Shell, Osaka Gas, Tokyo Gas and Chubu Electric Power Company. Project construction began in December 2009, and first gas is due in 2014.
A smaller footprint
Chevron has worked to minimise the project’s footprint on the island itself. A conventional survey – consisting of clearing paths to accommodate heavy trucks that haul necessary equipment – would have disturbed almost 3 square km of land. Instead, it was arranged for a freight helicopter to do most of the heavy lifting for the Gorgon project.
Approximately 15,000 separate lifts were made, while lighter equipment was carried by foot. This resulted in the disturbance of an area less than 0.2 square km.
Greenhouse gas management
Chevron says that the project is a “world-class example of environmental management” proving that “conservation and development can successfully co-exist”.
Since 1988, Chevron has:
• Replaced the offshore gas processing platform with an all subsea development; • Changed LNG process technology, including the CO2 removal medium, use of a dry compressor and hydrocarbon pump seals, and recovering flash gas from the nitrogen removal column and re-using it as fuel gas; • Improved waste heat recovery on the gas turbines resulting in a significant reduction in the use of supplementary boilers and heaters; and, • Significantly reduced greenhouse gas emissions resulting from the injection and subsurface storage of reservoir CO2.
When completed, the CO2 storage project at Gorgon will be the first in Australia to reduce greenhouse gas emissions by the injection of CO2 into an underground reservoir.
The CO2 injection will be located on the central eastern coast of Barrow Island near the gas processing plant. The injection wells will be directionally drilled from discrete surface locations to minimise the area of land required for the well sites, surface facilities, pipelines and access roads. Monitoring wells will provide a sample point within the injection area.
Once the carbon dioxide is injected into the subsurface, it will continue to move through the host reservoir, driven by the injection pressure and natural buoyancy until it becomes trapped. Chevron has said that the proposed LNG facility on Barrow Island has the potential to be among the most greenhouse gas efficient of its kind in the world. Natural gas can help reduce net greenhouse gases worldwide by displacing other fossil fuels.
Gorgon LNG sold globally will result in about 45 MMt/a less global greenhouse emissions, compared to the use of coal.
Barrow Island is a Class A Nature Reserve, therefore the Gorgon project required an extensive and thorough environmental protection plan. It is the world’s largest non-government quarantine initiative.
It’s estimated that Barrow Island is currently home for up to 60,000 golden bandicoots, 5,000 boodies, 10,000 speckled hare wallabies, and 10,000 possums. Some of Barrow Island’s thriving mammal populations are being relocated on the mainland as part of a unique conservation and restoration program in partnership with the Department of Environment and Conservation. For more than 40 years, it has also been home to a turtle rookery. Sea turtles nest on Barrow Island beaches between October and March each year – peaking in December and January.
Chevron has conducted baseline studies of sea turtles nesting in the area. This involves turtle tagging, counting sand tracks of nesting adults and emerging hatchlings and nest success data. Sea turtles also are tracked on their migration paths via a fitted satellite-linked tracking device. Each tagged turtle can be monitored by the public via an independent website specifically designed to track the migration of various sea turtles.
- Chevron’s Wheatstone LNG project to generate 6500 jobs (jobcontax.wordpress.com)
- Gorgon LNG Project – Facts and Figures (jobcontax.wordpress.com)
- Australia aiming to be the 2nd largest global LNG supplier by 2015 (jobcontax.wordpress.com)