ConocoPhillips Australia SH1 Pty Ltd is planning to undertake the Sequoia 3D Marine Seismic Survey (the ‘survey’) in Exploration Permit T/49P, in Commonwealth waters. At its nearest points, the survey area is located 23.5 km from the west coast of King Island and 26 km from the Victorian coast. Water depths in in this area range from 70 m to 1,000 m, with approximately 90% of the survey area being in water depths of less than 150 m.
The survey is scheduled to take place during the window of 10th August to 31st October 2021. This window of time is considered most suitable for survey acquisition because:
• Displacement of commercial fishing vessels is kept to a minimum;
• The Victorian and Tasmanian southern rock lobster and giant crab fisheries are partially closed;
• There is a low likelihood of presence of the pygmy blue whale and humpback whales in the survey area, with southern right whales present on the Australian coastline expected to migrate south towards the end of the survey window.
ConocoPhillips has worked with key stakeholders to ensure the protection of important species by excising giant crab habitat in the south-west corner of the acquisition area and southern rock lobster habitat in the Zeehan Australian Marine Park. There will be no full-power acquisition in these areas or within the 750m buffers applied to each. ConocoPhillips have also implemented a comprehensive southern right whale surveillance program to ensure the survey can be adaptively managed to protect this species.
ConocoPhillips has also developed a practical, evidence-based process to provide reasonable monetary adjustment to commercial fishers who experience a reduction of catch, displacement of fishing activity or fishing gear loss or damage during the survey.
The survey is expected to take approximately 60 days, though the vessel may be present on location for longer than this (but not acquire outside the months of August and October) depending on factors such as sea state, whale-instigated shutdowns and technical issues. The actual number of days of active seismic acquisition will be approximately 30 days.
The survey vessel will sail back and forth across the acquisition area along 42 sail lines between 500 m to 900 m apart, acquiring seismic data. Seismic sound will be generated from three acoustic source sub-arrays operating alternatively, one discharging as the others recompress, with a maximum source volume of 3,480 cubic inches (cui) and an operating pressure of 2,000 pounds per square inch (psi). The vessel will tow 16 hydrophone ‘streamer’ cables approximately 6,100 m long, which contain the sound sensors that detect the pressure and velocity of sound levels reflected from the geophysical structures being targeted.
The survey will use ConocoPhillips’ Compressive Seismic Imaging (CSI) technology, which means that while the overall width of the streamer configuration remains consistent, the survey can sail fewer line kilometres and use fewer streamers and acquire seismic data quicker than a conventional seismic survey.
