WesternGeco has completed a land and transition-zone 3D survey in Australia’s Barrow Island. The survey will be used as a baseline for the Gorgon carbon dioxide (CO2) sequestration project.
The baseline survey was designed to image the CO2 storage reservoir preinjection, and to optimize future CO2 injection well locations. Once injection begins, subsequent time-lapse surveys will monitor the CO2 plume migration.
The Gorgon gas project is the world’s largest land CO2 injection initiative. It is the first commercial energy project in Australia to significantly reduce greenhouse gas emissions with the underground injection of carbon dioxide.
Barrow Island is a class A nature reserve as designated by the Commonwealth of Australia, and is home to hundreds of unique and protected flora and fauna. An innovative approach was required for the baseline seismic survey that would set new guidelines for health and safety, regulatory land use, and environmental compliance requirements. Strict environmental requirements were met and in-depth management plans were put in place before the project could commence.
The survey was acquired over an area of 135 km2 (13,500 ha) of challenging terrain. Due to environmental legislation the project was restricted to 25 ha of land usage. This is a sizeable challenge for geophysical contractors as a typical unrestricted 3D survey of this size would normally require a minimum of 250 ha of land use for vehicular and seismic source access.
Three different energy sources were used for optimal results and minimal environmental impact. Much of the equipment was carried by hand with the line crews walking a combined distance of 25,000 km and carrying more than 880 t of equipment over some very hostile and uneven terrain. All of these efforts were to minimize the environmental impact and to keep the footprint of the baseline 3D survey under the allocated 25 ha. Part of the survey was acquired offshore where the vessel operated flawlessly around the delicate marine reserve.
The Gorgon survey was deemed a success technically, operationally, and environmentally.