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Energy & Utilities

Consideration of seabed condition and risk on lease area selection – A follow up Q&A with Gareth Ellery

22 Nov 2022, by

Our energy sector is at the precipice of a ‘gold rush’ as the offshore wind market takes off in Australia.

As this new industry expands, it is vital that developers choose the location of their projects wisely. This is a point Gareth Ellery from Global Maritime emphasised at the Australian Offshore Wind Conference when discussing the importance of considering seabed condition and risk on lease area section.

Speaking with us post event, Gareth answers key questions from our delegation on this important issue.

How do we encourage an open data sharing environment so that the additional value of data can be harnessed for non-competing applications?

First of all, Federal and State governments have to resolve conflicting polygons and export cable easements. Up until this point, collaboration will be difficult. Thereafter, we should convene working groups for developers in areas such as Gippsland, as has been done in the UK (e.g. Firth and Tay Developers Group – FATDOG). This can facilitate developer data sharing and also ensure that cumulative impacts are properly assessed and coordinated. The lack of coordination on cumulative impacts caused major issues in the UK.

Given the need for a license before doing any geotechnical surveys, how much certainty can we really gain from pre license geophysics?

A huge amount of data and value can be gained from pre-license geophysics surveys, if they are properly designed. The key issue is that these surveys will be cost constrained and so we need to do enough to inform early concept and downselection, which will in turn make for informed conversations with stakeholders and Traditional Owners, whilst being mindful of budget. In reality, this probably means full-coverage MBES and SSS data, to help inform early environmental studies and discussions around submerged cultural heritage, as a minimum. It is really important at the same time to get some seismic data, to investigate the sub-seabed conditions and to constrain preliminary ground models. Being pragmatic, this is probably going to comprise quite coarse grids of seismic lines, which can be infilled with post-license detailed survey. This data should be sufficient to create fence diagram type prelim ground models which can then be ground-truthed with geotechnical survey, after the feasibility license is granted.

There has been a lot of discussion about carbonate soils and how this presents challenges for OSW in Australia. Comments?

Australia has an advantage here in that the domestic O&G sector has been addressing carbonate soil challenges for some time. The first step has already been taken at this event, in that the risk is recognised. Next, we need to leverage the WA O&G sector experience in dealing with these issues, and make sure that appropriate characterisation of carbonate soils is factored into geophysical and geotechnical surveys. Essentially, carbonate soils are crushable, collapsible and exhibit high sensitivity (strength loss) when disturbed, so the post-installation strength and any possible strength regain needs to be quantified. They can be difficult to adequately sample with geotechnical survey equipment. They are not uniformly present in Australia and so many OWF developments will not encounter them.

Is there a risk that ground conditions change between the original survey and when construction starts?

Yes, the easiest example being sediment mobility. Some aspects of seabed change, such as mobility, can be predicted with successive surveys. Importantly, it is important to recognise that project seabed risk management is an iterative process with successive phases of survey increasing in detail, right up to construction start. Therefore, changes in seabed condition can be investigated and accounted for in design. It is also important to acknowledge that seabed conditions can change after construction and so seabed risk management should be considered right up until decommissioning.

I’d imagine accurate seabed data around a country is a national security matter from a geopolitical point of view. Won’t the government be reluctant to have such critical data made public?

We see a variety of approaches in different countries. In South Korea, data can only be provided to researchers using a South Korean phone and email address. In the UK, data is freely available, including data from constructed OWF, and those which have been abandoned. In Ireland, there is a treasure trove of very detailed seabed data available to the OWF developer. AusSeabed already provides direct and open access to a number of quite detailed seabed data themes, including site-specific survey which they have acquired proactively for activities such as CCS.

Have you given any consideration to submerged indigenous cultural heritage and how this might be impacted?

Yes, indeed. During the last glacial maxima, sea levels were up to 120m lower than today and so much of the shallow water shelf was inhabited in the past. In the UK, and other countries around the world, there are clear requirements to investigate the presence of any heritage features – from past inhabitation to shipwrecks – to avoid disturbance. There is a valuable opportunity for disciplines outside of engineering and OWF development to gain knowledge and insight from the data that we need to obtain. Requirements around cultural heritage must be developed with Traditional Owners and as an industry we need to be sensitive to this. The requirements must also be pragmatic and deliverable.

It would be great to have this sector as active contributors to AusSeabed, not just deriving from

100% agreed. As stated in my presentation, Australia is in many cases a frontier offshore development and so Geoscience Australia can greatly benefit from the data obtained to better understand the geological evolution of Australia. There has been great collaboration between the OWF industry in the UK and the British Geological Survey in a similar vein, particularly on projects such as Dogger Bank. I think it would be great if Geoscience Australia could designate a ‘lead’ to liaise with the Australian offshore wind industry to drive collaboration and contribution.

How easy has been in the UK to access existing private datasets? O&G data? What are the learnings for Australia?

A lot of historic data is held by the BGS in the UK, and widely available of their WebGIS platform. This has been incredibly valuable in early project de-risking and survey design. Outside of this, private data is still very difficult to access. In Australia, where in many sea areas data is sparse, the importance of getting access to proprietary and private data is even more important and this may be facilitated through non-competing projects in regional developer groups. The concept of centralised preliminary survey coordinated by Geoscience Australia could also be considered.

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