Site Surveys for Offshore Windfarms: How to Spend your Money Wisely in an Age of Austerity

Transcription

1 Site Surveys for Offshore Windfarms: How to Spend your Money Wisely in an Age of Austerity Richard Orren, Global Technical Head, Director Mark Finch, Geotechnical Director Senergy Survey and GeoEngineering

2 Setting the scene Big, new, engineering in an age of austerity Investment money tight Many alternative investment options Political uncertainties Tariff and revenue uncertainties Risks Bigger sites, big scale effects of small decisions Still lessons to be learned- from the earlier developmentsand O&G 2

3 Key factors to spend money wisely Spend money on the right things Spend money at the right time Spend money on the right area Spend money to answer only those questions you need to Buying cheap can work out very expensive Spend money wisely- get more risk reduction for your site investigation 3

4 Look before you leap Too many projects rush offshore let s get going- we need to get a survey Stop and do the desk studiesthe right ones- but you should have started them yesterday Scope them right- ask the right questions 4

5 Lessons learned Those old oil and gas chaps may be worth listening to after all... Wind farms are moving further offshore: into proper oil and gas territory Cheapest headline cost may well not deliver lowest cost results suitable results Weather risks are big both cost and schedule risks 5

6 The site desk studies Synthesise all available data for site into a single, integrated, seabed, soils and geohazard ground model Available data - sources Client supplied Public domain Senergy database/experience Available data - types Survey data Academic and public agencies Construction records O&G activity reports Metocean & environmental Output informs survey strategy Risk management early assessment 6

7 The surveys- reconnaissance vs detail 7

8 New generation bigger sites Sites are getting bigger, further offshore Beware of scale assumptions Even more geology and geological variability Foundation risks and cable risks 40 km 8

9 Bigger sites- but choose the right area Big sites= multi phase development Classify the site from a recce survey, to find the best area for Phase 1 development A model wind farm licence area 9

10 Recce survey informs strategy Recce survey results- informs foundation risks and cable risks Best seabed and soils Difficult seabed and soils Classify the site Find the best area for Phase 1 Do a detail survey over Phase 1 Phase 1 development area OK seabed and soils 10

11 Spend money on the right survey vessels Cheapest can work out expensive! Day running Craft Bigger vessels have benefits re: Safety Operational working limit Onboard data processing capabilities Coastal Craft Offshore Site Survey Vessel 11

12 Spend money on the right tools Murphys Law: Foundation depth of interest will always be approx where the first seabed multiple appears All sub bottom profilers are not the same- Each site and soil type will suit a particular system best Different tools for foundation and cable issues Multi-channel seismic gives the optimum image of the deeper foundation zone 12

13 Spend survey money at the right time Don t EVER survey in winter- or late autumn Use the right vessels and equipment to maximise efficiency Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1.0m 1.5m Percentage of time that is unworkable for survey- for a vessel and instrument suite that can work in 1.0m sig waves vs one that can work in 1.5m 13

14 % Unworkability Weather risk issues Summer season is short- consider multiple vessels in summer Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Weather windows are short- don t miss them Long endurance vessels improve the odds 14

15 Geophysical survey summary Do the right desk studies and use them Use reconnaissance surveys to classify the site and select the right area optimise and minimise the Detailed survey requirements Use the right boats and tools, at the right time of year Now we need to calibrate the geophysical datageotechnical investigations 15

16 Geotechnical campaigns Reconnaissance phase - after geophysics interpretation indicates soil provinces etc Detailed phase - after integration and concept selection Management of foundation risk 16

17 Geotechnical issues You don t save money by not spending it You will pay for a site investigation whether you do it or not and maybe several times over Plan the right amount of work at the right time Plan ahead geotechnical drillships are rare beasts Squeeze all the value out of the geophysical and the recce geotechnical surveys 17

18 Now spend money and time - integrating the data Integration means: Iteration Re-interpretation Revision Integrated interpretation Be prepared for change! Watch for innovations for better integration 18

19 Use this knowledge to make the right engineering decisions Foundation concept Economies of scale Turbine layouts Cable arrays and protection issues 19

20 Foundation Concept What are the right foundation concepts for your turbines? Not all detailed geotechnical surveys are the same Environmental restrictions? Significant design and construction risks can be locked in at this stage Look for innovation in design, construction & installation There should be no such thing as unforeseen ground conditions 20

21 How to spend money wisely Get good advice Do the right desk studies they re cheap Do a recce survey Do recce geotech + integrate Choose the right part of your licence area to develop Do detailed survey- not in the winter! Integrate again! Do detailed geotech + integrate again Choose the right foundation concepts to take to FEED Design - with risks greatly reduced! Did we mention get good advice? 21

22 Thank You 22