On the Oceanography of Brazil’s Equatorial Margin: Hazardous Offshore Currents and Strategies for Mitigation
1. On the Oceanography of
Brazil’s Equatorial Margin:
Hazardous Offshore Currents
and Strategies for Mitigation
Dave Fratantoni, Andre Gellers, and Neha Sharma
Horizon Marine, Inc.
Massachusetts, USA
2. Conclusions
• Brazil’s Equatorial Margin has both extraordinary development
opportunities and significant operational challenges.
• Strong and variable ocean currents are a primary concern.
• Exchange between blue-water and coastal regimes is poorly
Image Image
understood.
• A regional ocean observing and prediction system can provide
improved situational awareness to mitigate the impact of strong
currents on offshore operations, enhance safety, and protect the
environment.
3. Outline
• Geographic Context and Operational Challenges
• Oceanographic Environment
• Strategies for Mitigation
4. Image
Geographic Context
BEM potential may be
similar to West Africa
Zaedyus find in
French Guiana is
encouraging
Coastline is extensive,
sensitive
5.
6. Total
Quieroz Galvao
BP
BHP Billiton
Quieroz Galvao
BG
BP
OGP
BHP Billiton
ExxonMobil
Chevron
BP
OGP
BHP Billiton
OGP
Ecopetrol
ExxonMobil
Petrobras
7.
8.
9.
10. • Tides and tidal currents
• River outflow
Intense, persistent, and
vertically-complex
boundary current
Sensitive habitats
11. • Tides and tidal currents
• River outflow
Intense, persistent, and
vertically-complex
boundary current
Sensitive habitats
12. Operational Challenges
Image
ENSCO 8503
Tullow
French Guiana
• Remote location
• Extensive coastline with
sensitive ecosystems
• Strong and variable ocean
currents
• Poorly understood
connections between
offshore and coastal
regimes
Holding station
with 90% thrust
14. SeaWiFS Ocean Color
Image
Satellite observations are descriptive – but not always quantitative.
15. 12 years of surface drifter trajectories (n=450)
Color = Current Speed
16. Image
Why surface drifters?
• Direct measure of surface
velocity, exchange processes
• Analog for anything drifting at
the ocean surface
• Excellent for model validation
• Easy to deploy from a variety of
platforms
• Inexpensive robust statistics
17. Image
Histogram of all drifter-derived current
measurements in each BEM region
25. Models are ALWAYS wrong
Models can be useful if constrained
and validated by observations
We must know HOW the model is
wrong, and WHEN it can be trusted
26. Strategies for Mitigation
To mitigate the impact of strong ocean currents and
operate successfully in the equatorial margin we
require enhanced situational awareness, specifically:
• Accurate measurement of currents TODAY
• Accurate forecast of currents TOMORROW
28. A regional observation and prediction system
Image
• In-situ measurements of ocean currents
• Inexpensive
• Sustainable
• Spatially diverse
• Family of appropriate numerical models
• Global and regional blue-water ocean models
• Coastal models with accurate tidal and river forcing
• Local oil spill models for incident response
29. A regional observation and prediction system
• Seismic Survey
• Engineering Design
• Installation
• Diving
• ROV Operations
• Pipelaying
• Incident Response
32. Observing System Summary
• Surface drifters have been deployed
in the BEM about every two weeks
since July 2014
• Surveys utilizing expendables (CTD,
SV, CP) expected to begin in early
2015
• Regional 1/32o model run daily –
working on drifter data assimilation
• Interpretive reports generated weekly
33. Conclusions
• Brazil’s Equatorial Margin has both extraordinary development
opportunities and significant operational challenges.
• Strong and variable ocean currents are a primary concern.
• Exchange between blue-water and coastal regimes is poorly
Image Image
understood.
• A regional ocean observing and prediction system can provide
improved situational awareness to mitigate the impact of strong
currents on offshore operations, enhance safety, and protect the
environment.
• A prototype observing and prediction system is operational TODAY
34. Image
Thank you
Dr. David M. Fratantoni
Horizon Marine, Inc.
Massachusetts, USA
dave@horizonmarine.com
Mr. Andre Gellers
Horizon Marine do Brasil
Rio de Janeiro, Brasil
andre@horizonmarine.com