Santos is undertaking a 3D seismic marine survey over three petroleum permit areas in the Bonaparte Basin off the Western Australia and Northern Territory coast. The survey data is required to develop regional geologic models to inform the exploration and development strategy for several petroleum permits, and the potential location of future drilling of exploration and development wells.
Revision 0 and Revision 1 of the EP sought acceptance from NOPSEMA for a survey area that included three Full-fold Acquisition Areas (Areas A, B and C). However, for Revision 2 of the EP, Santos has opted to remove Full-fold Acquisition Area C and has reduced the survey Operational Area and Active Source Zone commensurate with this change.
The decision to remove Full-fold Acquisition Area C was made as part of Santos’ ongoing efforts to continue to reduce impacts and risks to ALARP and in response to concerns raised by stakeholders. Acquisition of Full-fold Acquisition Area C is no longer a priority for the survey and Santos considers it practicable to reduce the total Operational Area and to reduce potential impacts from the survey. The Operational Area has been reduced by 3,187 km2 (25%). The Revision 3 of the EP includes additional adaptive management measures for marine fauna and clarification of ESD principles in response to an opportunity to modify and resubmit the EP for Acceptance to NOPSEMA.
During the seismic survey, a vessel will travel along a series of pre-determined lines towing cables (known as streamers or acoustic receivers) which contain microphones (known as hydrophones). As the survey vessel travels along the lines, sound waves will be directed down through the water and into the geology below the seabed. The sound that reflects back is measured by the hydrophones and is later processed to provide information about the structure and composition of geological formations below the seabed.
The survey is planned to be acquired over two Full-fold Acquisition Areas, Areas A and Area B, and are separate from one another, but sail lines may continue within the defined Active Source Zone, with the seismic source operating between the two Full-fold Acquisition Areas during line run-ins and run-outs.
Due to this approach and the resultant improvement in operational efficiently the total survey timing has been reduced from 100 days to 60 days, with operations occurring on a 24-hour basis. An additional five days of contingency time within the operational area has been provided as part of the environmental assessment.
The timing of the survey is dependent upon vessel availability, weather conditions, stakeholder consultation feedback, the receipt of the required statutory approvals and the control measures within the EP.
