PGS proposes to acquire multi-client (MC) three-dimensional (3D) marine seismic surveys (MSS) within the North Carnarvon Basin and Beagle operational areas in waters offshore from Western Australia (WA). The recent EP resubmission is in response to NOPSEMA’s Request for Further Written Information.
Significant reductions to previous EP submissions have been implemented in this revision, including;
Size: the size of the proposed acquisition area has been reduced by approximately 86%.
3D only: the option for conducting any 2D seismic activity or CESM has been removed. Only 3D activity is to occur within the EP acquisition area.
Individual survey size: the maximum allowable survey size has been reduced by 30% to no more than 25,000 km2 of 3D acquisition.
These variations further reduce potential environmental impacts while ensuring greater efficiency in the management of uncertainties in future seismic surveys.
The operational areas are limited to the Commonwealth waters off the Pilbara coast only and are more than 180 km off Port Hedland and 75 km off Barrow Island
PGS do not intend to conduct survey operations over the entire operational area. Restrictions within the EP allow for a maximum of 25,000 km2 of seismic acquisition per year for 5 years. Further temporal and spatial restrictions also define when/where these surveys can take place.
Surveys will be undertaken with a purpose-built vessel. At-sea refuelling may occur but will only take place during daylight hours and not within a minimum distance of 30 km of Eighty Mile Beach Marine Park. A support vessel will always accompany the survey vessel.
Operational Details
The proposed 3D marine seismic survey(s) will be like previous surveys conducted in Australian waters, with no unique or unusual equipment or operations proposed. The largest sound source that PGS will use for any survey within the operational area will have a capacity no greater than 3,260 cui.
During the proposed survey activities, the survey vessel will traverse a series of pre-determined sail lines within the operational area at a speed of ~4.5 knots. The operating pressure for the seismic acoustic source will be ~2,000 psi, with the 3D acoustic source deployed in two arrays. Independent Marine Fauna Observers will be deployed, ensuring compliance with EPBC Act Policy Statement 2.1 and the mitigation measures identified within the EP.
Timing of the Activity
Specific commencement dates and durations of individual surveys within the operational area have not yet been determined.