3D Oil Limited propose to undertake the Dorrigo three-dimensional (3D) marine seismic survey (MSS) in the Commonwealth waters of the Otway Basin within Exploration Permit T/49P which lies adjacent to Tasmania. The Dorrigo MSS is located entirely within Commonwealth waters, approximately 18 km west of King Island (Tas) and 56 km south of Cape Otway (Vic). Water depths in the survey area are between 80 – 1420 m with seismic data acquisition undertaken in water depths between 100-840m.
 
The Dorrigo MSS operational area is 4350 km2. The full-fold acquisition area where seismic airguns will be operational covers an area of 1580 km2 within this larger area. Airguns will not operate outside the operational area. The operational area incorporates necessary space for vessel manoeuvring such as line run-ins, run-outs, line-turns, refuelling and resupply by support vessels. Two additional vessels are planned to support the Dorrigo MSS activities.
 
The proposed seismic source will have a total capacity of not more than 3260 cubic inches and will be towed at approximately 4.5 knots a short distance behind the seismic vessel at a depth of approximately 7 m. Ten solid hydrophone streamers measuring approximately 6000 m in length and spaced up to 125 m apart will be towed at a depth of 8-25 m below the surface behind the survey vessel. The seismic source will be discharged every 12.5 m along a series of parallel north-south lines spaced between 500-720 m apart.
 
The Dorrigo MSS is expected to take up to 35 days between 1 September and 31 October 2019.  This period avoids the Bonney upwelling period, the associated presence of marine megafauna in the survey area and other marine users.