The use and application of meteorological data in support of the offshore oil and gas can assist In all aspects of operations. From the use of climatological data for pre-operational planning or for design purposes through to real-time weather forecasts for ongoing and weather-sensitive operations, the application of reliable and accurate meteorological data can have a significant impact on safety and cost effectiveness.
Weather and climate have a major impact on many aspects of life, and perhaps more so in the harsh environment of the North Sea than in many other spheres.
Whilst "weather" is usually taken to refer to those conditions which may be expected over the next few days, "climate" is generally assumed to mean the average conditions which occur over a long number of years - and hence the conditions which are likely to be met in any succeeding year. This latter definition will only hold true if we assume that the climate is not undergoing a significant change, but even so, climate change is generally a gradual process and hence statistical data derived from past years of historical data are still likely to give an adequate indication of conditions which can be expected.
In determining, for example, the times of year when a specific offshore operation can be undertaken, or the optimum time for performing this operation, climatological data 1s frequently used. Various databases of marine operations are available based on observations taken by merchant ships, and often presented in the form of summarised monthly statistics for a particular area. It IS important to note that the data are not specific to a location but are gathered over sometimes quite a wide area and hence some care should be taken in their use.
A typical monthly summary might contain tables of average wave height against wave period, wind speed against direction, etc., and are certainly of use in the initial planning of an operation. Again, because we are dealing with ship data some caution is advised, since, when possible, ships will avoid areas of severe weather and consequently there is at least an implied bias towards fair weather conditions in the summarised data.
Many environmentally related problems require a time-continuous database for achieving an optimum solution. From a time-continuous database it is possible to determine such information as:-
The total amount of downtime to be expected for an activity or series of activity.
The probability of an operation being completed within a specified time period.
The optimuin sequence of activities to take advantage of likely weather conditions.
The persistence of environmental conditions such as wave height or wind speed to aid in fatigue/stress analysis.
Since long period wave records are rarely available, it is necessary to use a different approach to obtain a time-continuous database of wave parameters. A commonly used time-continuous database is the Global Spectral Ocean Wave Model (GSOWM) produced by the United States Navy.