2D Seismic Survey WA-532-P, WA-533-P and WA-50-L

Overview

INPEX is proposing to undertake a two-dimensional (2D) seismic survey of Exploration Permits WA-532-P and WA-533-P in the Browse and Offshore Canning Basins. The 2D seismic survey will also include the acquisition of seismic data in Production Licence WA-50-L, also within the Browse Basin

The permit areas are located wholly within Commonwealth waters. At the closest point, the survey activity will be undertaken over 87 km west of Broome and 42 km offshore from the Dampier Peninsula. Seismic data acquisition will mainly take place in water depths between approximately 50 m and 600 m below mean sea level. However, some seismic data acquisition may occur in shallower areas located at Lynher Bank in the southern part of WA-532-P where the shallowest water depth is approximately 30 m, and east of WA-533-P where the shallowest water depth is approximately 37 m.

The survey will be undertaken by a seismic survey vessel towing an underwater seismic source and a single streamer behind it. The seismic source will be towed behind the vessel at water depths of approximately 5-10 m. The seismic source will use compressed air to emit regular pulses of sound which reflect off the seabed and underlying geological rock formations and structure boundary. The reflected sound will be received by the streamer, which may be up to 6-10 km in length and will be towed behind the survey vessel at a water depth of approximately 5-15 m.

During the survey, the seismic survey vessel will sail along the pre-determined acquisition lines at a speed of approximately 4.5 knots (approximately 8 km/hr), discharging the seismic source approximately every 18.75 m (approximately every 8 seconds). Data will be acquired along a grid of broadly-spaced, approximately orthogonal lines (spaced approximately three to six kilometres apart) within the ‘Acquisition Area’ with associated vessel movements and support activities undertaken within the ‘Operational Area’.

Based on the environmental risk assessments presented in the Environment Plan (EP), an acceptable window of opportunity was determined to be from 1 November to 31 May in any calendar year that the EP applies.

In the event that seismic acquisition is unable to commence on 1 November 2021 due to prolonged COVID-19 restrictions, further provision to commence the activity in November 2022 or November 2023 has been allowed for in the resubmission, as follows:
• 1 November 2021 – 31 May 2022 (planned acquisition)
• 1 November 2022 – 31 May 2023 (contingency only)
• 1 November 2023 – 31 December 2023 (contingency only).

The duration of the survey activity will comprise approximately 140 days of seismic data acquisition. To allow for potential adverse weather and operational downtime, the survey may occur over a longer period, and so the survey vessel may be present in the Operational Area for up to 210 days.

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