Archer 3D Marine Seismic Survey
Santos WA Northwest Pty Ltd (Santos), who are wholly owned by Santos Energy Limited, propose to undertake a 3D seismic marine survey (the ‘survey’) over a portion of exploration permit areas WA-437-P and WA-541-P and surrounding waters in the Bedout Sub-basin in Commonwealth waters off the coast of Western Australia. At its closest point, the survey Operational Area is located approximately 49 kilometres (km) from the nearest land (Bedout Island), 87 km from the nearest mainland coastline (Larrey Point, near the De Grey rivermouth), and 102 km from the nearest regional town Port Hedland.
The survey data is required to develop regional geologic models to inform the exploration permit retention strategy, and the potential location of future drilling of exploration and development wells.
Seismic acquisition will be via methods and procedures similar to other seismic surveys conducted in Australian waters. The seismic survey vessel will travel along a series of pre-determined lines towing cables (known as streamers or acoustic receivers) which contain microphones (known as hydrophones). As the survey vessel travels along the lines, sound waves will be directed down through the water and into the geology below the seabed. The sound that reflects back is measured by the hydrophones and is later processed to provide information about the structure and composition of geological formations below the seabed.
Santos intends to acquire the full survey in 2021. However, should this not be achievable, the full survey may be acquired in 2022. The survey will only be acquired in one of these years. It will not be acquired in both years. The timing of the survey is dependent upon vessel availability, weather conditions, stakeholder consultation feedback, the receipt of the required statutory approvals and the control measures within this EP. .
In order to avoid sensitive fish spawning and whale migration periods, acquisition of the survey will only be undertaken between 1 February to 31 July in either 2021 or 2022.
The survey will take at least 38 days to complete, with operations occurring on a 24-hour basis. An additional 5 days of contingency time within the operational area has been provided as part of the environmental assessment.
The survey Operational Area defines the area within which the seismic survey and support vessels will operate and is approximately 4,752 km2. Water depths across the Operational Area range from ~63 m to 106 m.
The Survey Area is comprised of the Active Source Zone and Full-fold Acquisition Area. The Full-fold Acquisition Area is the area within which the seismic source will be operated in full acquisition mode to achieve the geophysical objectives of the survey. This zone is approximately 1,600 km2, with water depths ranging from 70 m to 96 m. The Active Source Zone surrounds the Full-fold Acquisition Area and typically, this zone will be used to incrementally build the power of the seismic source from non-operation to full capacity, for soft starts. This zone is approximately 2,114 km2, with water depths ranging from ~67 m to 99 m.