Biofouling or ‘biological fouling’ is the accumulation of microorganisms, plants, algae, or animals on wetted surfaces.
The offshore oil and gas industry are responsible for a multitude of different assets underwater which these organisms grow on, but why do they become an issue and how does the industry solve this? Emma Learmonth, Director of AQUASIGN, highlights why this serious issue causes problems and tells SOS Magazine how by mimicking fish skin, they are combatting this problem for their clients:
Biofouling causes a raft of significant issues for companies working in subsea environments. Being a subsea marker provider, we look at this issue from a visibility and safety perspective – safety and asset identification should be just as important subsea as is common practice on the surface. Marine organisms attach and grow on substrates, making it very difficult and sometimes impossible to locate and operate equipment, therefore a divers job becomes much more onerous.
Other serious issues caused by biofouling include:
1. Additional weight load and drag:
FPSO or similar vessel hulls can become covered in marine growth making them heavier to power and consequently use more fuel, which has both financial and environmental impacts. For large static structures, such as fixed platforms biofouling impacts hydrodynamic loading, increasing the stress placed upon the structure over its predicted life span. These will require regular maintenance and inspection to evaluate the integrity of the structure to ensure it is not impaired.
2. Safety of personnel:
Biofouling makes it difficult to identify specific equipment or locations. Marine growth will always find a way to attach to substrates, with the process accelerated in shallow warm water where settlement can occur in just a few weeks. When divers carry out work in such a safety critical environment they need to be able to identify assets and complete their assignments as quickly and safely as possible. A safety critical example being, identifying the correct valve and knowing if it is in ‘open’ or closed’ position.
Barnacles and other hard animal type fouling organisms can become wide spread over time and erode the equipment surface. Barnacles develop their own ‘glue’ that can stick to almost anything requiring intrusive cleaning methods to remove, which can damage the surface providing the perfect substrate for other marine life to grow.
4. Non-identification of damaged areas:
When conducting scheduled operations or condition monitoring, maintenance issues may not be reported as they could be hidden under a thick fouling layer. External cracks and damaged constructive elements become difficult to identify.
The above reasons impact the safety of subsea operations and the environment at large: biofouling, even at its lowest level, impacts the identification of assets. The rate and volume of marine growth will fluctuate geographically depending on water depths and temperatures, therefore every offshore oil and gas project will be affected in some way.
What can stop biofouling?
The old school approach was to kill off marine growth, however, regulations have become far more stringent over the years banning the use of harmful biocides and toxins to protect the marine environment.
Historic methods may have been effective when equipment was initially deployed however biofouling starts its life as bacteria which adapts to its environment and will return. Operators of long term developments know that fouling needs addressed regularly.
There are various mechanical methods for removing fouling, however this is a costly exercise and has no sustainable or eco-friendly attributes. It can be extremely tough to remove hard fouling without causing damage to equipment.
Our flagship product Aquasign was originally developed by Shell Thornton Research as a unique solution that mimicked fish skin. Have you ever seen a fish covered in coral, seaweed or mussels?
There are two key elements to the antifouling properties; primarily creating a hydrophobic surface to which marine growth cannot attach – basically the wettability of the surface means the organisms simply cannot attach as opposed to being killed off by use of copper nickel, toxins or biocides. The second element to our smart silicone technology is the controlled non-toxic oil release, basically selfrenewing the slippery surface ensuring damaged areas remain marine growth free even in static conditions.
Our continued research and development programs guarantee our products provide an anti-fouling solution for all marine environments and can be attached to every type of subsea equipment. Our 3rd party testing include programmes that are designed to mimic both the forces of impact from deployment as well as the long-term pressures of deep water.
For further information on Aquasign please visit: www.aquasign.com/subsea-markers
Or call: (01224) 897060