Seeing Beneath the Seafloor: How Ultra-High Resolution Seismic is De-Risking Offshore Wind

As the offshore wind industry scales up to meet global renewable energy demands, safety and precision are non-negotiable. The complexity of engineering these massive projects involves many variables, but one of the most critical is understanding what lies beneath the waves. Identifying hidden geological hazards is essential for preventing accidents, reducing the risk of costly project delays, and securing the safety of personnel and equipment.

To address this challenge, research institutes like Fraunhofer IWES are applying ultra-high resolution multichannel seismic (UHR MCS) technology to deliver an unmatched level of clarity into sub seafloor conditions, which is crucial for the entire lifecycle of an offshore wind farm.

A New Focus for a Proven Technology

While multichannel seismic methods were originally developed for the oil and gas industry, their application in offshore wind requires a significant shift in focus. Unlike hydrocarbon exploration, which targets structures several kilometers deep, wind farm developers are primarily concerned with the top 100 to 200 meters of the seabed. In this shallow environment, they need to identify geological features at a meter and even sub-meter resolution to ensure the stability of turbine foundations.

UHR MCS has been specifically adapted for these conditions, using high-frequency acoustic sources and arrays of closely spaced receivers (hydrophones) to create exceptionally detailed 2D or 3D images of the subsurface.

From Sound Waves to a Digital Ground Model: The Fraunhofer IWES Process

Creating a reliable picture of the sub seafloor is a multi stage process that transforms raw acoustic data into actionable intelligence.

1. Customized Data Acquisition: An offshore survey campaign is carefully designed based on the client's needs and existing geological knowledge of the area. Fraunhofer IWES uses a customized, modular acquisition system that can be tailored to achieve the required depth and spatial resolution.
2. Advanced Onshore Processing: Once collected, the data undergoes thorough processing to filter out noise, remove artifacts, and improve the clarity of the seismic images.
3. Expert Geological Interpretation: Geologists meticulously interpret the processed data to identify key geological structures and layers.
4. Integrated Ground Model: Finally, the UHR MCS data is integrated with other datasets, such as hydroacoustic or geotechnical data, to build a comprehensive ground model.

The Power of Precision: How Ground Models Drive Safer, More Efficient Projects

This detailed ground model is the foundation for informed decision-making throughout a project's lifecycle, providing critical insights that help to:

• Identify Hidden Hazards: The model can reveal a wide range of potential hazards, including buried channels, unstable soils, obstructions like boulders or potential unexploded ordnance (PUXO), shallow gas pockets, and weak layers of organic material.
• Optimize Foundation Design: A comprehensive understanding of sediment composition (sand, clay, peat, etc.) is essential for designing foundations that can withstand environmental forces. Soft sediments may necessitate deeper foundations, while harder substrates can allow for more straightforward anchoring techniques.
• Mitigate Construction Risks: By detecting potential hazards early, engineers can modify construction methods to mitigate risks effectively. This proactive approach helps projects avoid delays, budget overruns, and equipment damage that can occur from unanticipated obstacles like pile refusal or soft zones.
• Plan Secure Cable Routes: In addition to turbine placement, the detailed geological data is invaluable for determining the most efficient and secure routes for inter-array and export cable installation.

A Lighter Touch: Minimizing Environmental Impact

Beyond safety and cost efficiency, UHR MCS technology also offers a significant environmental benefit. The high resolution of the seismic data enables more precise and targeted geotechnical sampling. This significantly reduces the need for extensive and intrusive seabed drilling, lessening the environmental footprint associated with site assessments while also conserving resources and time.

As the demand for renewable energy continues to grow, the importance of accurate geological characterization cannot be overstated. By integrating advanced geophysical data and innovative engineering solutions, the offshore wind industry can continue to expand safely and sustainably.

Learn more about Fraunhofer IWES's expertise in offshore site characterization: www.iwes.fraunhofer.de/en.html