1. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Derivation of Ground Models and Characteristic
Geotechnical Profiles in Offshore Wind Farms at pre-
FID stage
V A Terente, M J Owen, D M Higgs & G Ellery

2. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
• Brief Introduction to Cathie Associates
• Background and Key Terminology
• Pre - FID
• Ground Risk and Ground Models
• Geotechnical Profiles
• The Challenge of Deriving Ground Models for Offshore Windfarm Investment Decisions
• Current Practise for Investigations and Modelling
• Proposed Implementation Approach for Integrated Ground Models
• Adequate Specification of Surveys
• Geotechnical Interpretation and Unitisation
• Geophysical Data interpretation & Integration
• Application of required design codes for UB, LB, BE
• Project Example
Contents

3. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Cathie Associates
• Offshore Geotechnical Engineers, Geophysicists,
GIS Specialists and Engineering Geologists
• Medium size firm; one of the few offshore
European specialists with worldwide experience
(~50 staff)
• Offices in the UK, Belgium, France, Italy and
Germany
• Trusted by leading developers, operators and
contractors for our integrity and expertise
• Pushing the frontiers of offshore technology
http://www.cathie-associates.com/

4. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Background and Key Terminology
Pre-FID: Pre – Funding Investment Decision for
Offshore Wind Farms
1.5 – 2.5 Million Euro/MW or >1Billion Euro for a typical 100no. 6MW Turbine
development
Pre – FID Ground Models
http://www.bizmdosw.org/
UK trade and Investment 2015

5. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Background and Key Terminology
Ground Risk = Investment Risk
• The costs of foundation and cable
installation is approximately 30% of a
typical Offshore Windfarm.
• Controlling Ground Risk at an early stage is
is key for:
• Defining the right foundation solution
• Assess cable installation
requirements
• Complete the preliminary design of
foundations
• Quantifying material and construction
costs, etc.
Pre – FID Ground Models
http://www.bizmdosw.org/us-offshore-wind-faq/

6. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Background and Key Terminology
Ground Models
Fookes (1997) : ‘A representation of the
geology of a particular location...’
Author (applied to offshore wind
farms):
‘A spatial model of geological formations,
sufficiently robust as to allow an
assessment of their variability’
Pre – FID Ground Models

7. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Background and Key
Terminology
Geotechnical Profiles
‘Extrapolated Geotechnical
property profiles at turbine
locations’
Must be sufficiently accurate
as to allow the preliminary
sizing of foundations, or the
assessment of geotechnical
risks’
Pre – FID Ground Models

8. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
The Challenge of Deriving Suitable Ground Models:
Scale and Geological Complexity of Offshore Wind farms
Pre – FID Ground Models

9. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Current Practise
Ground Models for
Offshore Windfarms
OSIG - Guidance notes for
the planning and execution of
geophysical and geotechnical
ground investigations for
offshore renewable energy
developments, 2014
Pre-FID
Desk study > Preliminary GI >
Detailed GI > Pre-FID Ground
Model
Pre – FID Ground Models
OSIG Guidance notes for the planning and execution of geophysical and geotechnical ground investigations for offshore renewable energy developments, 2014

10. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Proposed Implementation
Approach
• Adequate Specification of
Surveys
• Geotechnical Interpretation and
Unitisation
• Geophysical Data interpretation
& Integration
Key targets:
• Determine Geological Unit
Boundaries
• Assign Geotechnical Profiles to
Each Unit
Pre – FID Ground Models

11. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Proposed Approach for Integrated
Ground Models
Adequate specification of surveys
• Vessel capability (downtime/weather
sensitivity)
• GI standards
• Sampling strategy
• Drilling requirements
• In situ testing
• Laboratory tests
Pre – FID Ground Models

12. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Proposed Approach for Integrated Ground Models
Geotechnical Interpretation and Unitisation
http://offshorewind.rvo.nl/file/download/43061512
Pre – FID Ground Models

13. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Proposed Approach for Integrated Ground Models
Geotechnical Interpretation and Unitisation
Pre – FID Ground Models

14. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Proposed Approach for Integrated Ground
Models
Geophysical Data Interpretation and
Integration
Pre – FID Ground Models

15. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Pre – FID Ground Models
Application of required design codes for UB, LB, BE

16. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Pre – FID Ground Models
Pre-FID Geotechnical Profiles

17. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Pre – FID Ground Models
Example Project – Hornsea OWF

18. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Pre – FID Ground Models
Example Project – Hornsea OWF

19. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Pre – FID Ground Models
Conclusions
• Implementation Method for the derivation of
Ground profiles based on:
1. Robust desk based ground model
2. Adequate specification of surveys
3. Integration of interpreted geophysical
and geotechnical data
4. Robust statistical assessment
5. Application of specific design codes
Key Outputs:
• Geological unit boundaries
• Extrapolated geotechnical profiles at each
turbine location

20. ISOPE, Rhodes 2016 Derivation of Ground Models and Characteristic Geotechnical Profiles in Offshore Wind Farms at pre-FID stage
Pre – FID Ground Models
Thanks
Victor Terente
victor.terente@cathie-associates.com
www.Cathie-associates.com