TGS-NOPEC Geophysical Company Pty Ltd (TGS) propose to undertake a three-dimensional multi-client marine seismic survey (3D MC MSS) in the Otway Basin, in Commonwealth waters offshore from Victoria, and Tasmania (referred to as the Otway Basin 3D MC MSS). The survey will provide 3D data coverage and improved subsurface imaging to provide an improved understanding of the subsurface, which to-date has been limited to sparse 2D coverage.
The Operational Area (OA) represents where all activities managed under the EP will occur and includes the Acquisition Area (AA). The OA is located ~38 km from land at the closest point.
The AA lies within the OA and is where seismic acquisition will occur. Smaller discrete surveys will be acquired within the AA which covers ~45,000 km2; however, this entire area will not be surveyed. Water depths within the AA range from 115 m to 5,650 m.
The Otway Basin 3D MC MSS will also include a ‘tie-in’ to existing geophysical data from previously drilled wells. The 2D tie-line will overlap with 3D data acquisition in the AA; however, it will also extend onto the Continental Shelf and represents a few hours of active source time in shallower waters. At the shallowest point, the tie-line is in a water depth of approximately 115 m and additional control measures will be implemented for this.
A single Seismic Vessel will tow up to 14 seismic streamers 8 – 10 km long. The Seismic Vessel will travel at ~4.5 knots. The acoustic source will either be a ‘dual source’ (comprising two source arrays discharged alternately) or a ‘triple source’ (comprising three source arrays discharged alternately). Each acoustic array will have an effective volume of up to 3,480 in3.
The Otway Basin 3D MC MSS may commence as early as 1 October 2023 (pending regulatory approval) and will be completed by 30 September 2027. The maximum acquisition time during any calendar year is 200 days with a maximum of 400 days over the duration of the EP; however, due to temporal controls for managing impacts to various environmental sensitivities, the duration is likely less. Based on an analysis of weather and sea state, acquisition is likely to occur from October to March. However, the EP does not prescribe a specific timing for activities for the entire AA, as the precise timing is subject to NOPSEMA’s acceptance of the EP, weather conditions, vessel availability and other operational considerations, as well as the seasonality of environmental and socio-economic sensitivities.
This EP details the processes involved in assessing the potential risks and impacts to the different receptors within the receiving environment and relevant persons that utilise the area. Included within this assessment are the proposed control measures and operational procedures that will be implemented in order to reduce the potential adverse environmental impacts from the planned operational activities, and risks from unplanned events, to As Low As Reasonably Practicable and to Acceptable Levels. Environmental performance standards have been developed to measure the performance of the control measures and operational procedures that will be implemented throughout the Seismic Survey.
NOPTA Title application: NEATS Ref: 6265X5
