Firm Foundations: Geophysical Data for Ground Modeling

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To build robust models it is generally advisable to draw from a diverse set of input sources. Geophysical data complements geotechnical data in subsurface investigations, UHR3D seismic data in particular offers a richer source material with denser measurements, that can be acquired faster and at lower cost.

Moving from the seismic to the geological and geotechnical domain with confidence with ultra-high-resolution 3D seismic (quantitative interpretation data, imaged by PGS).

Geophysical data provides subsurface physical properties, such as density and velocity of materials. On the other hand, geotechnical data involves direct sampling and testing of soil and rock, and provides ground truth for calibration of geophysical data.  Understandably, many geotechnical engineers are most comfortable with geotechnical data, as it is what they are most familiar with. PGS works with end users to help them understand the link between geophysical and geotechnical data.

PGS cut its teeth in the oil and gas industry, revolutionizing the efficiency and effectiveness of subsurface mapping and imaging. Now it aims to move the offshore wind site characterization business forward by introducing 3D seismic more rountinely, and specifically UHR3D. Widespread adoption of 3D surveys has the same potential to significantly reduce subsurface uncertainty in offshore wind as it did for the oil and gas industry.

Once acquired, processed and interpreted, the next step for using the UHR3D data is to develop a ground model combining geophysical and geotechnical data to enable an integrated understanding, in 3D, of the stratigraphy, properties and hazards of the chosen site. This in turn will allow teams to evaluate the optimal turbine locations. 

Efficient project planning requires understanding and mitigation of potential risks   in the shallow subsurface. The earlier you know about the specific challenges, the better chance you have of staying on track with the development plan and producing an optimized layout that does not require re-working later and, importantly, does not change other project decisions and procurement and construction activities.

Building a Living Ground Model

The consolidation of all data and interpretation within a living ground model can provide actionable insight built on contiguous data rather than interpolated estimates.

The promise of 3D is its ability to efficiently sample a far larger area with a richer and denser array of data points. By reducing reliance on interpolation, the geotechnical program can be better optimized to sample all indicated facies and features, instead of oversampling some and overlooking others. 

Densely sampled 2D provides some insights but it takes 3D data to understand the full picture.  

With high-quality seismic data, it should also be possible to refine the quality of synthetic CPTs (cone penetration tests), further reducing the time spent on geotechnical sampling.  Currently geotechnical sampling represents roughly 80% of costs, compared to 20% spend on UHR3D, signaling that there is significant money to be saved by delivering on the promise of 3D and its ability to confidently predict quantitative ground properties.  

The true value of 3D thus has three benefits: site risk reduction, the overall cost of the program, and reduced turnaround time. It is the ability to accelerate delivery of first power from a new site that holds the most significant potential and is the true value of 3D seismic for offshore wind.

PGS geoscientists are working with academia and industry partners on proof of concept projects demonstrating the uses of UHR3D data to derisk site characterization. 

Compress the Site Characterization Timeline Using 3D Data

PGS recognizes the value of detailed subsurface characterization and can deliver efficient and scalable acquisition and imaging solutions to serve the fast-growing offshore wind industry. We can enable you to reduce risk and time to operation with our optimized solutions for site characterization, ground model generation and geohazard identification.

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