The Eureka 3D MSS is a typical 3D survey using methods and procedures similar to others conducted in Australian waters.
The Active Source Area (ASA) comprises the area within which 3D seismic acquisition will be undertaken and covers approximately 946 km2. The ASA is surrounded by a larger Operational Area (OA) (approximately 1,575 km2), for the purpose of vessel approach, line turns, and necessary maintenance operations. The Seismic Source will not be discharged within the OA. The OA at its closest is approximately 6 km west of Dongara and 54 km south of Geraldton. The seismic survey will be undertaken in water depths between approximately 10 and 60m.
The survey will involve a single seismic survey vessel towing a seismic source array with a total volume of 2,495 cubic inches (in3), at a water depth of approximately 6-7m. The seismic source will use compressed air to emit regular pulses of sound that reflect off the seabed and underlying rock formations. The reflected sound wave will be received by a minimum of 6 hydrophone streamers. Each streamer will be up to 6,150 m in length, spaced 100m apart and towed at a depth of approximately 7m. During the survey, the seismic survey vessel will travel at a speed of approximately 4.5 knots, discharging the seismic source approximately every 5 seconds. The survey vessel will typically acquire seismic data along a series of adjacent and parallel lines in a “racetrack” pattern with north-south sail lines. When the vessel completes the line, it will turn again to follow another line offset several kilometres from the previous line. This pattern is repeated until the required coverage is completed.
The shallow waters within the survey area present a potential technical and safety challenge for the survey vessel. The vessel master at the time may decide that the shallower areas are better acquired using an Ocean Bottom Node technology rather than towed streamers. This will require deployment of the small and light weight nodes, via diver or autonomous vehicle, in a square grid of approximately 250m x 250m in the required areas.
The Eureka 3D MSS will take a maximum of 40 days to acquire and will be undertaken within the acquisition window of February to March (inclusive) during either 2025 or 2026. The precise timing of the survey is subject to vessel availability, weather conditions and other operational considerations, and will consider the seasonality of environmental sensitivities, where practicable.
