T/30P Geophysical and Geotechnical Seabed

Overview

Lattice Energy Limited (Lattice), who are wholly owned by Beach Energy Limited (Beach), propose to undertake a geophysical and geotechnical survey (site survey) over a portion of their T/30P permit and open acreage in the Otway Basin in Commonwealth waters. At its closest point, the site survey is approximately 76.5 km from the township of Port Campbell, Victoria.

The site survey is required to inform the location of future drilling of an exploration well and identify potential hazards.

The geophysical survey is required to obtain detailed bathymetry measurements and detect hazards on or below the seabed. Geophysical data will be acquired from the same vessel in two parts:

Geophysical survey to collect bathymetry data and detect hazards using the following: Multibeam echo sounder; Side-scan sonar; Sub-bottom profiler; Magnetometer; Ultra-Short Baseline Positioning System; and Sound Velocity Profiler and Conductivity, Temperature and Depth profiler.

High resolution two-dimensional shallow reflective imaging (2D survey) to inform shallow gas hazards. Equipment for this survey will consist of a sound source of up to 160 in3 and one 1.2 km streamer towed by a vessel at a speed of approximately 8-9 km/hr (4 – 5 knots).

The geotechnical survey is required to collect detailed information on the properties of the seabed and the underlying shallow sediments to build a picture of the local geology of the area and support geophysical data collected. The geotechnical survey, which may be undertaken from the same vessel as the geophysical and 2D survey or from a separate vessel, consists of: Coring; Cone Penetrometer Test; and Grab samples.

The site survey will take up to 28 days based on 21 days of survey time and 7 days for transits and setting up of equipment. Timings for each survey component is detailed below.

The site survey is proposed to be undertaken between 1 February 2020 to 30 April 2020 or 1 October 2020 to 31 December 2020. Timings of the survey is contingent on the availability of suitable vessels, weather and the receipt of required environmental approvals. The site survey will be undertaken in the following order, with only one vessel undertaking each component at a time:

• Geophysical survey – 7 days
• Geotechnical survey – 6 days
• 2D survey – 8 days

The survey area refers to the area where data acquisition will occur. This is a 6 km x 6 km area totalling 36 km2. The operational area refers to the area encompassing the survey area. It is where the geophysical and 2D survey vessel will run in and out to ensure there is a full coverage of the survey area and where the vessels will turn for the next survey line. This is a 10 km x 10 km area totalling 100 km2. Water depths across the operational area range from 150 m to 1,110 m.

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