Reducing offshore drilling and construction risks with Metocean data
Mark Calverley R&D manager – Fugro Metocean Business Line
Society of Petroleum Engineers(SPE) London Evening Programme Meeting 26th April 2016
1 SPE Evening Programme Meeting 26 April 2016 www.fugro.com Outline
• Metocean – what, why? • Drilling • Metocean Considerations • When to measure? • Construction • Weather risk • Understanding forecasts
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Winds
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Waves
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Courtesy of NASA's Goddard Space Flight Center 5 SPE Evening Programme Meeting 26 April 2016 www.fugro.com
Physical Oceanography
• Temperature • Flow assurance • Conductivity • Density • Member weights • Sound Profile • Survey
6 www.fugro.com Engineering / Metocean Interactions
Engineering Marine Warranty Engineering Operations Schedule / Legislation
Metocean Regional Metocean Data Metocean Data Oceanography Requirements Analysis
Model Spatio-temporal Installation Modelling Choice Grid size
Instrument Sampling Installation Measurements Choice Strategy
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Structural / Budget Challenges
Exploration
Metocean Metocean Strategy Drilling Contractors
Engineering design
8 www.fugro.com Metocean Strategy across the life cycle
Risk Cost
9 www.fugro.com Metocean for Drilling – Operational Planning / Engineering
• Selection of drilling platform • Jackup
• Generally wave dominated forces • Water levels also important • Current / wind loading of less importance • Jacking operations most vulnerable
• Reliable wave criteria • Reliable water level criteria • Joint probability of wave/water levels • Knowledge of temporal variability to optimise jacking operations
10 www.fugro.com Metocean for Drilling – Operational Planning / Engineering
Selection of drilling platform • Drillship • Semi-sub (DP) • Semi-sub (anchored)
• Wave directionality of importance to drillships • Directional differences between loading important • Wave period critical
• Currents important to station keeping and riser analysis • Wind loading important in areas of squalls
11 www.fugro.com Metocean for Drilling – Operational Planning / Engineering
Areas of Uncertainty • Hindcast Model reliability (atmospheric, waves, currents) • Analysis Methods • Response modelling • Metocean processes not represented in models (temporal or spatially)
DNV Guidance note: For meteorological and oceanographic data a minimum of three to four years of data collection is recommended.
Planning generally based on hindcast data:
• Temporal and spatial resolution • Validation / verification
12 SPE Evening Programme Meeting 26 April 2016 www.fugro.com Atmospheric Model reliability
Atmospheric Models Assimilation data – helps to define current state of the atmospheric – informed by satellites, observations (>8,000 Metar/Synop)
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Wave Models Assimilation data – helps to define current state of the wave field – informed by satellites (altimeter / SAR / GNSS*), observations (order of magnitude fewer than meteorological stations)
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Current Models Assimilation data – helps to define current state of the ocean circulation– informed by satellites (altimeter / SST), observations (3000 Argo floats)
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Limitations of models recognised • Certainly in forecasting, lead to the implementation of ensemble forecasting • Needs end user to understand
Standard deviation of a Probability map for temperature temperature ensemble forecast
16 www.fugro.com Temporal Considerations
What is the temporal resolution of the model data?
• 1-hourly • 3-hourly • 6-hourly
What is the lead time for an operation? What is the duration of an operation?
What are the time scales of the Metocean processes? Some processes not well represented in models include:
• Squalls • Solitons • Polar lows
Use of complementary data, e.g. satellite data.
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Spatial Considerations
Model resolution
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Spatial Considerations
Model resolution
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Spatial Considerations
Can the models capture the spatial scales of the Metocean processes. For example polar lows.
During planning can you rely on the geographic registration of frontal features?
Do the models domains extend, at appropriate resolution, to topography / coastlines that might drive
the wind forcing?
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Is the environment severe?
Can the requirements be addressed by a desk study? • Are metocean processes that impact drilling considerations properly represented? • Early commission of a desk study might help to understand risks.
Prospectivity – could site specific measurements add value to fast tracking development?
Are data needed in region for other assets?
Cost constraints – typically measurements prior to discovery are increasingly rare outside frontier regions such as Barents Sea.
Typical year long metocean measurement campaign equivalent to 4 or 5 days downtime!
21 www.fugro.com Metocean for Drilling – Real time support
• Forecast reliability informed by site specific measurements
• Operational decision making
• Legislative requirements (e.g. CAA CAP437, NTL)
• Informing future development through site specific data collection
22 www.fugro.com Forecast reliability
Does not provide information of timing of frontal systems.
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24 www.fugro.com Soliton Early Warning System
Soliton generation Andaman Sea zone
2 x Real-time SEWS moorings Malacca Strait SEWS#1 Sumatra SEWS#2
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Warning Level Current Speed Actions (knots) Record the solitons in daily 24-hour LOW < 1.5 summary, but no warning required or action to be taken by the rig
MEDIUM 1.5 to 2.0 Issue soliton warning by email, but the rig will probably not take action
Issue soliton warning by email and follow HIGH 2.0 to 3.0 up by calling OIM. The rig will tighten anchor wires and standby
Issue soliton warning by email and follow VERY HIGH > 3.0 by calling OIM. Rig will prepare for possible disconnect
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27 www.fugro.com Data to support Development
Drilling platforms offer a relatively cheap measurement opportunity.
Leverage to collect data to understand reliability of hindcast models supporting engineering, particularly valuable for current models.
Provide measurement of processes beyond model capabilities, e.g. squalls. DNV requirement to engineer against measured winds.
28 www.fugro.com Where do the uncertainties /risks lie?
Hindcast Model reliability (atmospheric, Forecast Model reliability (atmospheric, waves, currents) waves, currents)
Analysis Methods Metocean Awareness
Response modelling Measurement QA
Metocean processes not represented in models (temporal or spatially)
29 SPE Evening Programme Meeting 26 April 2016 www.fugro.com Metocean within construction
Planning Transport / Execution Analysis Data to support operational Ways to forecast / measure Quantification of downtime, planning. Metocean conditions for Accuracy of forecasts, etc. Ways to characterise Metocean operational planning. conditions for operational planning. Forecast considerations.
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Assume an operation west of Shetland with £250k day rate.
1. Joint frequency distribution based on 4m threshold on significant wave height.
2. Joint frequency distribution based on 4m threshold on significant wave height and peak period below 10s
3. Persistence based on significant wave height and 18 hour duration.
4. Weather windows analysis based on: • 18-hour duration • Operational threshold = 4m, Tp > 10s; 2.5m, Tp < 2.5s
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32 SPE Evening Programme Meeting 26 April 2016 www.fugro.com Weather Cost Exposure August September Analysis Hs =4m Hs=4m, Hs=4, Tp<10s Durn>18hr Downtime days August 0.45 8.2 0.10 September 3.47 18.62 4.13 Downtime cost August 112,375 2,056,452 24,800 September 868,500 4,656,458 1,031,250 Sep-Aug 756,125 2,600,006 1,006,450
WOW (hours) Weather cost (£) August September Average 1.9 8.0 20,060 83,177 Maximum 54.0 96.0 562,500 1,000,000 P10 6.0 30.0 62,500 312,500 P20 0.0 12.0 - 125,000 P30 0.0 0.0 - -
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Fatigue potential is high. Compare Metocean design conditions of transport to those experienced. Directly measure fatigue. Identify potential issues for inspection prior to installation.
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Forecast Reliability
Measurements
Response Modelling
Metocean Awareness
35 SPE Evening Programme Meeting 26 April 2016 www.fugro.com Forecast (Model) Reliability
Weather Forecast Meteorologist rqd. Independent WF Maximum WF Level on site source interval A Yes (1) 2(2) 12 hours(3) B No(4) 2(5) 12 hours C No 1 12 hours
1. There should be a dedicated meteorologist, but it may be acceptable that he/she is not physically present at site. The meteorologist opinion regarding his preferable location should be duly considered. It is anyhow mandatory that the dedicated meteorologist has continuous access to weather information from the site and that he/she is familiar with any local phenomena that may influence the weather conditions. 2. It is assumed that the dedicated meteorologist (and other involved key personnel) will consider weather information/forecasts from several (all available) sources. 3. Based on sensitivity with regards to weather conditions smaller intervals may be required. 4. Meteorologist shall be conferred if the weather situation is unstable and/or close to the defined limit. 5. The most severe weather forecast to be used.
DNV-OS-H101- Marine Operations, General
How is the forecast generated?
36 SPE Evening Programme Meeting 26 April 2016 www.fugro.com Are all forecasts equal?
• How is the forecast generated? • Which models support the forecast? • What other ‘guidance data’ supports the forecast? • Does the forecaster have regional experience? • Are observations available to the forecaster? • Are the synoptic difficult / easy to forecast?
37 SPE Evening Programme Meeting 26 April 2016 www.fugro.com Alpha Factors WF Operation WF WF WF starts
Estimated time for the operation Contingency
TPOP (Basis for selecting α-factor) TC
TR
Required weather window with
OPWF = α x OPLIM
α Design Hs = 2m Design Hs = 4m
TPOP A B C A B C ≤12 0.76 0.80 0.95 0.83 0.87 1.00 ≤24 0.73 0.77 0.84 0.80 0.84 0.87 DNV-OS-H101- Marine ≤36 0.71 0.75 0.77 0.77 0.80 0.80 Operations, General
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Alpha Factors Reliability
• No requirement for 2nd forecast to be forecaster driven, many companies use model driven forecasts to reduce cost.
• Potential for underlying models to be similar, e.g. public domain models such as WW3 or ECMWF.
• No consideration of ensemble forecasting
• Reliability of site specific forecasts not addressed.
• No consideration of reliability of models and forecasting under different synoptic conditions.
• No consideration of personnel competency
39 SPE Evening Programme Meeting 26 April 2016 www.fugro.com Forecast Reliability – Dichotomous Approach
Result Forecast
Hit event forecast to occur, and did occur
Miss event forecast not to occur, but did occur
False Alarm event forecast to occur, but did not occur
Correct negative event forecast not to occur, and did not occur
Observed
yes No Total yes hits false alarms forecast yes Analysis no misses correct negatives forecast no
Total observed yes observed no total
Requires investment in measurement and forecasting prior to construction. Potential to use exploration phase to build this.
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Measurements - Site specific
Measurements provide:
• Confidence in forecast model (does T+0 match reality) • Potential to reduce DNV α factor • Confidence in data during operation and for contractual purposes (weather claims) post execution. • Potential to offer early warning systems
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Measurements - Spatial Technologies
Measurements can provide a spatial picture.
• Vessel Mounted Acoustic Doppler Current Profilers (4 knot limit) • Airborne current measurement systems (ROCIS uses optical imagery to provide surface current data)
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Response Modelling
Joe Bloggs
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Structural Monitoring
Measuring Environmental Forces provides one half of the equation.
The other half is the motion response and structural response
Consideration should also be given to measuring structural responses during construction.
Examples include:
• Motion sensors • Not a single sensor but at critical locations, e.g. crane tip, launch points, etc • Strain measurements
Likely driven by critical components/operations.
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Metocean Awareness
The data consumer!
Convert data into decisions!
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Metocean Awareness
The data consumer!
Convert data into decisions!
Parameter (s) Operating Status limit
Hs
Tp
Ws
Cs
WL
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Execution Summary
Understand forecast provenance / reliability.
Complement forecasts with measurements to reduce risk.
Consider use of spatial measurement techniques to identify frontal features.
Consider use of remote measurements to provide early warning..
Help to drive new technology adoption – operators/contractors often very conservative.
Move to decision making systems rather than Metocean data systems.
Incentivise risk management!
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Analysis
Contractors Plan
Lessons Execution Learned
Operational Forecast Performance performance
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Technology Helping Hands
Marine Autonomous Systems offer a low cost way to collect spatial measurements • Market movement • Regulatory framework being established (MAS RWG) • Cost driven market (analagous to diver to ROV) • System includes analysis and delivery of relevant information to end user. • Low power sensor / increasing power capability
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Technology Helping Hands
Designing Monitoring for data and generation evaluation and capture
Data driven Data decision generation making and under capture uncertainty
Big Data Wheel
Data Data driven storage, insights access
Visualising Big data big data, modelling models and and analysis analytics
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Summary
• Create an open dialogue with Metocean experts. • Evaluate Metocean based risks with respect to operations / engineering design through workshops rather than just reports. • Consider cost benefit of different Metocean strategies (model versus measured, etc) with full cognisance of risks. • Ensure timely consideration is provided.
• Provide Metocean awareness training to staff (for example IMarEST Metocean Awareness Course)
• Include Metocean in project stage gates.
Remember Chaos Theory was introduced by a Meteorologist (Edward Lorenz) in his 1972 paper entitled "Predictability: Does the Flap of a Butterfly's Wings in Brazil Set Off a Tornado in Texas?"
51 www.fugro.com Thank you.
Questions?
Mark Calverley [email protected] 01491 820546