Pelican 3D Marine Seismic Survey

The CarbonNet Project conducted a marine seismic survey in Bass Strait in February 2018.

The purpose of the survey was to gain deeper knowledge of the underlying geology of the area to help confirm the potential for geological carbon dioxide (CO₂) storage. Preparation for the survey involved stakeholder consultation and regulatory and environmental approvals.

Survey method and equipment

Seismic surveying is commonly used in the resources industry to gain a better understanding of subsurface geology.

Marine seismic surveys are carried out by a specialised vessel towing a sound wave source that produces sound pulses in a controlled frequency range at set intervals.

The sound signals are reflected back by underground rock formations and are captured by hydrophones (acoustic receivers) in 'streamers' that are also towed by the vessel. The data collected by the hydrophones is recorded on board the vessel for later analysis and interpretation.

Image used with permission from FishSAFE Information Project 2017 – FishSAFE.org.

Location

The survey covered approximately 166km² offshore from Golden Beach (between Loch Sport and Seaspray), Gippsland.

The survey took place within the greenhouse gas assessment permits:

VIC-GIP-002 (in Commonwealth waters)
GGAP006386(V) (in Victorian waters) managed by CarbonNet.

Map showing the survey area which covers approximately 166 square kilometres offshore from Golden Beach (between Loch Sport and Seaspray), Gippsland.

Timeframe

The seismic survey was completed in February 2018.

Survey Completion

The survey was acquired during February 2018, using the Polarcus Naila a purpose-built seismic vessel towing eight recording cables (‘streamers’), each 4km long. The survey vessel was escorted by two scout vessels to check that the water depth was as previously mapped, and that no sandbanks had shifted to pose a risk to the environment, the vessel, or its equipment.

The survey was completed safely with no environmental incidents or disturbance of marine animals or plants, as confirmed by pre- and post-survey environmental assessments.

Highly detailed geological mapping of reservoirs in the subsurface

Modelling of CO2 storage

Once the full seismic interpretation was completed, geological modelling took place in order to determine the optimal location for the Gular-1 offshore appraisal well.

This geomodel (Figure 4) represents the 3D distribution of reservoirs and seals, their structural conformation within the overall Pelican anticline, and the detailed distribution of rock properties such as porosity (the space between rock grains that is filled by aquifer fluids), and permeability (the ease with which these fluids can flow through the reservoir rocks).

Geomodel used to optimise the Gular-1 appraisal well location