How Sea Conditions Impact Offshore Operations Around the World
Why is it important to understand specific Sea Conditions?
Offshore structures are at the mercy of their environment. Weather phenomenon (such as cyclones, tropical rain, sumatras, shamals, monsoons, earthquakes, and tsunamis) present unique safety and operational risks for offshore companies.
But each region has a diverse ecosystem. Understanding how to tackle the specific weather risks associated with an area is a vital part of offshore planning.
For example, certain combinations of weather and sea ice formations can make it difficult for vessels to travel through the Baltic. When the Sea of Bothnia is frozen, and the passage to the Gulf of Finland is open, it can lead to tricky ice navigation. When a low passes over Scandinavia, it brings strong N/NE winds over the Sea of Bothnia. These strong winds can cause breakaway ice moving into the path of vessels, causing navigation problems. If high pressure over Russia blocks the low, the situation can persist for some time.
However, knowledge of these specific conditions in the North Sea is not necessarily transferrable to other regions. Weather phenomenon around the world presents regionally specific challenges to offshore projects.
For offshore structures to withstand the impact from the weather, planners must factor in these specific environmental considerations in their designs. Rig selection, equipment handling, as well as riser design and mooring systems are also dependent on the predicted site-specific sea conditions.
Failure to consider the conditions typically result in unplanned downtime, operational disruption, and safety risks to the crew and equipment.
How do Sea Conditions Impact Offshore Operations?
Sea conditions can impact all aspects of an offshore project. Be it drilling, survey, salvage, construction or heavy lifting; unpredictable sea conditions may cause severe economic and operational stress on a project.
As a result, risk mitigation plans are an essential part of offshore projects in the planning and design phases. The objective is to maximize gains while minimizing typical operational interruptions, such as:
1) Installation is one of the most expensive stages in an offshore project cycle. When planning an installation activity, project planners need to consider having access to weather monitoring stations to obtain weather forecasting reports. These reports provide valuable information on the atmosphere, wind, waves, swells, and currents and allow the project planner to create response plans based on these predictions.
2) Specific operations, such as jack-up movement and positioning, may also be limited by sea conditions. Depending on the weather, work may have to stop, for example, in severe storm conditions. Therefore, weather forecasting is critical to keep the crew and equipment safe.
3) Semi-submersible support, such as flotel (floating hotel), tender assistance or utilities support, are not as sensitive to moderate sea conditions. However, they also require accurate forecasting, as severe weather will still impact these structures and approaching storms will halt operations. It is essential that severe weather is correctly identified and forecasted, to prevent safety risks to the crew and limit unplanned downtime.
The Guiding Mandate
The regulation requires offshore duty holders to collect information on sea conditions. The information needed is based on the foreseeable operating conditions (e.g., based on the operating limits set out in the safety case). The collected information includes: (a) wind speed and direction (b) the sea condition (c) air temperature (d) barometric pressure (e) visibility, cloud base and cover (HSE Report, 2019).
Site-specific sea conditions affect the safety of activities carried out or around the offshore installation (e.g., loading or unloading and, in particular, helicopter operations). In more extreme cases, they may affect the ability to implement emergency plans. Monitoring of sea conditions is therefore vital for offshore, to keep projects both safe and on track.
Want to learn more?
Download the Offshore Sea Conditions Guides. It's our six-part series, explaining the key characteristics of sea conditions around the world. Each edition explores how specific conditions affect offshore operations, and what you can do to minimize the impact of these conditions on your next project.
The areas covered in this series are:
● The North, Norwegian & Barents Sea
● Gulf of Guinea (West Africa)
● South African region
● Congo River Mouth - Angola
● South China Sea
● Middle East Region (Persian Gulf / Arabian Sea).