REAL TIME METOCEAN ASSISTANCE TO OFFSHORE OPERATIONS - PROVISION OF PRECISE SWELL FORECASTS CALIBRATED THROUGH WIND AND SEA-STATE SATELLITE MEASUREMENTS : COBO PLATFORM INSTALLATION CASE STUDY

Demonstration Case Study (Ref: 345135)

I Name:

REAL TIME METOCEAN ASSISTANCE TO OFFSHORE OPERATIONS - PROVISION OF PRECISE SWELL FORECASTS CALIBRATED THROUGH WIND AND SEA-STATE SATELLITE MEASUREMENTS : COBO PLATFORM INSTALLATION CASE STUDY

II Keywords:

Primary Keywords: Forecast, Marine operation, Oil

Secondary Keywords: Sea-state, Wind, Waves

III Summary:

Marine operators, like ELF and TPG, need to be provided with accurate swell forecasts in order to take operational decisions.
Elaborated in MétéoMer, this application make use of technologies which have been developed since 1991 in the frame of ESA pilot projects. This procedure use satellite wind and sea state as well as field measurements and lead to a permanent control of the meteo analyses so that forecast are 'a priori' reliable in a 0-24h interval or more.

IV Description:

1 Customer Need:

Prior to offshore platform installation in environments subject to long period swells (Guinea Gulf for example), sea operators need to be provided with the most accurate swell forecasts giving precisely predicted parameters: amplitude, period and direction respectively with 20cm, 1s and 5° accuracies. These values, further inputs to codes of installation procedures are calibrated through the use of satellite wind and sea state as well as of field measurements.
Relying upon these procedures, operational decision-taking must be irrevocable, be it for operation launching or postponing, thus requesting predicted events of the utmost precision.

2 Method:

Some years ago, one realized that forecasts were accepted as valid 'a posteriori' whereas operations managers have an 'a priori' need for 95% reliable forecasts up to and beyond 24h. The altimeter, scatterometer and SAR in wave mode satellite measurements now allow a different approach for swell forecasting, in particular for the Guinea Gulf.
Calculation results issued from MétéoMer ISFS model (Integrated Swell Forecasting System) are combined both with field and satellite measurements for a continuous validation at several steps :

  1. for the global analysis, particularly in swell generating areas for which analyses are refined and validated with measurements. Scatterometer and altimeter data are assimilated to wind fields from numerical models (ECMWF for example) to obtain accurate forecasts.

  2. for calculations nearby the operation area on available satellite measurements locations

These different calibrations lead to a permanent control of the meteo analyses and exactness of our ISFS calculations so that forecasts are 'a priori' reliable in a 0-24h interval or more.

3 Result:

This technology is undertaken in MétéoMer by two marine meteorologists, while one operator implements swell, current and tide measurement equipments linked to an Inmarsat communication system (Standard C) for data exchanges between the area and our office.
Satellite information is also available at MétéoMer through a direct link with ESRIN-Frascati for reception of LBR measurements in a 2-4 hours delay. Data are processed on a Sun station as well as meteo analyses and amendements and ISFS calculations.
Moreover, Meteosat pictures are also permanently received.
Final synthesis are continuously available and meteo reports are sent every 12 hours.

Jacket installation

Installation of platforms, as the use of very draught barges, on areas where swell have a determining impact on the feasibility of that kind of offshore operations, suppose a very specific ocean forecast assistance.
For the good achievements of these in-depht operations, operators require sea-state guaranteeing the highest accuracy (20cm, 1 second and 5°). The predicted events should be accurate enough to take decisions without any possible return.


Orthodromic lines converging to the point of intersest

Orthodromic lines converging to the point of intersest

These weather forecast are achieved by a set of method incuding :

These different comparisons enable to check the accuracy of meteorological analyses and correctness of our calculations and offer an a priori guarantee of the forecasts on a 24 hours period and more.

4 Deliverables:

MeteoMer supply forecast reports of wind and sea-state including wind-sea and swell (Hs with the associated periods and directions).

5 Customer opinion:

With this assistance, ELF and TPG benefited from metocean reliable information in operational conditions.
In case of platform installation, such procedures offer an increased guarantee on the metocean conditions and allow the coordination of companies actions for irrevocable operational decisions.

6 Cost / Benefit:

Cost for this service is around 450 Ecu per day, including data cost. On site, cost for MétéoMer operator implementing the measurement equipment is 400 Ecu per day whereas daily cost for the equipment is 600 Ecu. ( operations for platform installation range from 7 to 23 Mecu per day).

V References:

  1. Customer References

    Customer1 Customer2
    Name: Mr. Chasseguet Mr. Thomas
    Company: ELF Angola TPG
    Address: Tour ELF La Defense
    92078 Paris cedex 45 France     		Kupka C, 14 rue Hoche
    92902 Paris la Defense France

  2. Provider References

    Name: Mr Lasnier
    Company: MeteoMer
    Address: Quartier les Barestes - RN7 - 83480 Puget sur Argens - France
    Tel: +33 (0)4 94 45 66 11
    Fax: +33 (0)4 94 45 68 23
    E-mail: 4meteomer@meteomer.fr
    Web: www.meteomer.fr www.meteomer.com  

  3. Scientific References

    Name: Mr Lasnier
    Company: MeteoMer
    Address: Quartier les Barestes - RN7 - 83480 Puget sur Argens - France
    Tel: +33 (0)4 94 45 66 11
    Fax: +33 (0)4 94 45 68 23
    E-mail: 4meteomer@meteomer.fr
    Web: www.meteomer.fr www.meteomer.com