On the Oceanography of Brazil’s Equatorial Margin: Hazardous Offshore Currents and Strategies for...

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

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•  Brazil’s  Equatorial  Margin  has  both  extraordinary  development  opportuni;es  and  significant  opera;onal  challenges.  

•  Strong  and  variable  ocean  currents  are  a  primary  concern.  

•  Exchange  between  blue-­‐water  and  coastal  regimes  is  poorly  understood.  

•  A  regional  ocean  observing  and  predic;on  system  can  provide    improved  situa;onal  awareness  to  mi;gate  the  impact  of  strong  currents  on  offshore  opera;ons,  enhance  safety,  and  protect  the  environment.  

Conclusions

Outline

•  Geographic  Context  and  Opera;onal  Challenges    •  Oceanographic  Environment  

•  Strategies  for  Mi;ga;on  

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Geographic Context

BEM  poten;al  may  be  similar  to  West  Africa    Zaedyus  find  in  French  Guiana  is  encouraging    Coastline  is  extensive,  sensi;ve  

Total  Quieroz  Galvao  BP  BHP  Billiton  

Quieroz  Galvao  

BG  BP  OGP  BHP  Billiton  

ExxonMobil  Chevron  BP  OGP  BHP  Billiton  

OGP  Ecopetrol  ExxonMobil  Petrobras  

•  Tides  and  ;dal  currents  •  River  ouQlow  

Intense,  persistent,  and  ver;cally-­‐complex  boundary  current  

Sensi;ve  habitats  

•  Tides  and  ;dal  currents  •  River  ouQlow  

Intense,  persistent,  and  ver;cally-­‐complex  boundary  current  

Sensi;ve  habitats  

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Operational Challenges ENSCO  8503  Tullow  French  Guiana  

•  Remote  loca;on  

•  Extensive  coastline  with  sensi;ve  ecosystems  

•  Strong  and  variable  ocean  currents  

•  Poorly  understood  connec;ons  between  offshore  and  coastal  regimes  

Holding  sta;on  with  90%  thrust  

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Oceanographic Environment

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SeaWiFS  Ocean  Color  

Satellite  observa;ons  are  descrip;ve  –  but  not  always  quan;ta;ve.  

12  years  of  surface  dri/er  trajectories  (n=450)    

Color  =  Current  Speed  

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•  Direct  measure  of  surface  velocity,  exchange  processes  

•  Analog  for  anything  dri]ing  at  the  ocean  surface  

•  Excellent  for  model  valida;on  

•  Easy  to  deploy  from  a  variety  of  plaQorms  

•  Inexpensive  à  robust  sta;s;cs  

Why  surface  dri/ers?  

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Histogram  of  all  dri]er-­‐derived  current  measurements  in  each  BEM  region  

Average  measured  current  speed  as  a  func;on  of  WATER  DEPTH    Gray  dots  are  all  measurements  

Average  measured  current  speed  as  a  func;on  of  WATER  DEPTH    Gray  dots  are  all  measurements  1000  m  

1/3-­‐deg  Gridded  log(NDATA)  

Number  of  hourly  velocity  esAmates  from  dri/er  posiAon  record  

1/3-­‐deg  Gridded  Current  Velocity  

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Numerical  Ocean  Model    VELOCITY  (kts)  

Models  are  ALWAYS  wrong  

Models  are  ALWAYS  wrong  

Models  are  ALWAYS  wrong    Models  can  be  useful  if  constrained  and  validated  by  observa;ons    We  must  know  HOW  the  model  is  wrong,  and  WHEN  it  can  be  trusted  

Strategies for Mitigation

To  mi;gate  the  impact  of  strong  ocean  currents  and  operate  successfully  in  the  equatorial  margin  we  require  enhanced  situaAonal  awareness,  specifically:    •  Accurate  measurement  of  currents  TODAY  

•  Accurate  forecast  of  currents  TOMORROW  

Observa;ons   Forecast  Model  

A regional observation and prediction system

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•  In-­‐situ  measurements  of  ocean  currents  •  Inexpensive  •  Sustainable  •  Spa;ally  diverse  

•  Family  of  appropriate  numerical  models  •  Global  and  regional  blue-­‐water  ocean  models  •  Coastal  models  with  accurate  ;dal  and  river  forcing  •  Local  oil  spill  models  for  incident  response  

A regional observation and prediction system

•  Seismic  Survey  •  Engineering  Design  •  Installa;on  •  Diving  •  ROV  Opera;ons  •  Pipelaying  •  Incident  Response  

A regional observation and prediction system

ObservaAon  System  Status:    18  Sep  2014    

ObservaAon  System  Status:    18  Sep  2014    

•  Surface  dri]ers  have  been  deployed  in  the  BEM  about  every  two  weeks  since  July  2014  

•  Surveys  u;lizing  expendables  (CTD,  SV,  CP)  expected  to  begin  in  early  2015  

•  Regional  1/32o  model  run  daily  –  working  on  dri]er  data  assimila;on  

•  Interpre;ve  reports  generated  weekly  

Observing System Summary

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•  Brazil’s  Equatorial  Margin  has  both  extraordinary  development  opportuni;es  and  significant  opera;onal  challenges.  

•  Strong  and  variable  ocean  currents  are  a  primary  concern.  

•  Exchange  between  blue-­‐water  and  coastal  regimes  is  poorly  understood.  

•  A  regional  ocean  observing  and  predic;on  system  can  provide    improved  situa;onal  awareness  to  mi;gate  the  impact  of  strong  currents  on  offshore  opera;ons,  enhance  safety,  and  protect  the  environment.  

•  A  prototype  observing  and  predicAon  system  is  operaAonal  TODAY  

Conclusions

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Thank you

Dr.  David  M.  Fratantoni  Horizon  Marine,  Inc.  Massachusejs,  USA  dave@horizonmarine.com  

Mr.  Andre  Gellers  Horizon  Marine  do  Brasil  Rio  de  Janeiro,  Brasil  andre@horizonmarine.com