“It is estimated that the Arctic holds around 30% of the world’s undiscovered natural gas and 13% of its yet-to-find oil. This amounts to around 400 billion barrels of oil equivalent, 10 times the total oil and gas produced to date in the North Sea.”
Developing the Arctic could be essential to securing energy supplies for the future, but it will mean balancing economic, environmental and social challenges,” according to Shell.
The search for oil and gas by exploration companies is becoming ever bigger and no corner of our planet is out of reach (or is it?).
Exploration focuses on areas where extreme temperatures are the norm. The Arctic for example has many untapped resources but working in this type of climate poses new challenges to owners and operators with ambient temperatures as low as -60° Celsius.
Manufacturers of equipment for use in these areas have to find solutions which will operate effectively and reliably in such cold weather climates.
Winterisation measures are those which ensure an offshore vessel is prepared for operation in cold climates focusing on the adverse effects and the control of icing, freezing and wind chill. This article has been written as an informative piece about winterisation of offshore platforms, FPSO and FSUs but also focuses on managing onshore process plant through severe weather.
We highlight some of the issues faced by owners and operators when working in cold climates and look at the new DNV Guidelines : DNV-OS-A201 (Winterization for Cold Climate Operations).
DNV GL developed this new offshore standard which came into effect in April 2014 and covers the technical requirements to control the adverse effects of freezing, icing and wind chill on offshore equipment and systems.
T&D are experts in Electrical & Process Heating solutions and our article goes on to focus on how heat tracing cables can be used for some winterisation applications in cold climates.
This introductory article will be a forerunner to a future series of “products and solutions” focused posts.
We shall cover space heating, immersion heaters and anti-condensation heaters. Active measures are those which primarily rely on energy to address adverse effects of icing, freezing or wind chill e.g., heat, physical force and circulation of liquids.
The risks posed by extreme temperatures vary but are very real. Obviously humans will be a little “chilly” if temperatures fall to -60°C. Perhaps not so obvious is the fact that the structural integrity of an offshore platform can be compromised with as little as 50mm of ice build up.
Whilst operators and owners are more than aware of the problems and risks, they are not necessarily fully conversant with the complexities involved in designing and specifying solutions for winterisation.
One major design consideration which can easily be overlooked is the amount of energy consumed by the active measures specified.
Although winterisation of mobile units and offshore installations is not a new objective for any oil and gas company, for cold climates, some companies still rely on standards which have been prepared for ships operating in such conditions.
However, a winterisation strategy for ships will not necessarily suit offshore oil and gas platforms. DNV GL standard DNV-OS-A201 defines its objective as :-
“ Ensuring that a vessel is capable of and suitably prepared for operations in cold climates. This is provided for by setting functional requirements to functions, systems and equipment considered important to safety and which are intended to be in operation in cold-climate conditions.”
The standard provides three levels of winterisation requirements: basic, cold and polar. This enables owners to select the correct winterisation strategy based on climate conditions. It should be noted that it is the end users responsibility to specify the correct level.DNV
The guidelines set out provisions for anti icing, anti freezing and de-icing of equipment, plant and exposed areas, explanations of which are below and taken directly from DNV-OS-A201.
Anti-icing : Measures to prevent ice from forming on surfaces, structures or equipment. The intent of anti-icing is that the surfaces, structures or equipment are immediately available.
Anti-freezing : Measures to prevent fluids freezing within systems, structures or equipment. The intent of anti-freezing is that the systems, structures or equipment remain functional and are not damaged as a consequence of fluids freezing.
De-icing : Measures to remove snow and ice from surfaces, structures or equipment. The intent of de-icing is that the surfaces, structures or equipment can be made functionally available within a reasonable time period.
For further reading please click the link below
To discuss any of the points raised above or to obtain assistance with your sites winterisation plan please do not hesitate to contact Thorne & Derrick
HAZARDOUS AREA ELECTRICAL & PROCESS HEATING EQUIPMENT
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By Thorne & Derrick International