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EXPLORING BEYOND THE BARRIER
Dr Bob Oram, Technical Director, Balmoral Offshore Engineering, discusses advanced deepwater ROV buoyancy systems
The rapid pace of subsea development sees operations in water depths beyond the traditional 10,000ft/3000msw barrier becoming commonplace. The discovery of commercially-viable reservoirs in these extreme water depths has driven parallel development programmes in all areas of equipment associated with deepwater activity. The availability of ROVs and AUVs with matching deepwater capabilities is therefore an essential requirement. Whilst new-build deepwater ROVs have traditionally been specified with a 3000msw operating depth rating, the growing trend is to specify 5000msw capability. For those businesses where ROVs may be required to work in non-oilfield markets, depth ratings of 6000-7000msw are increasingly specified.
Alongside this requirement to operate in extreme depths has come the demand to handle progressively more complex and heavy tooling packages.
Whilst operating depth and payload capabilities have increased, the traditional requirement for ROVs to be as compact and manoeuvrable as possible has remained unchanged. This requirement has necessitated the development of lower density buoyancy foams to negate the standard trend of increasing foam density, and therefore buoyancy block dimension, with increasing depth rating and payload requirement. As future tooling requirements are rarely obvious at the time of initial design, ROV contractors have recognised the advantage of having ROV buoyancy systems which are readily suitable for field modification. So-called ‘pure syntactic foams’, i.e., syntactic foams which do not contain large macrospheres, are particularly suitable for such activities.
Composite foam systems
Balmoral Offshore Engineering is an established developer of advanced composite syntactic foams and has introduced a portfolio of flotation systems which have established the new benchmark for syntactic buoyancy.
A ‘composite’ buoyancy system refers to a syntactic foam comprising glass microspheres and macrospheres held together within an epoxy resin system to create a homogenous matrix. Please refer to Table 1.
These systems are cast using dedicated mould tooling providing repeatable consistent production and are therefore ideally suited in applications such as work class ROVs - particularly on a multi-build requirement. Composite ROV buoyancy blocks comprise an
integrated shell to ensure maximum protection of the core material in the event of accidental impact.
Pure foam systems
In parallel to the development of composite, ie, macrosphere- containing syntactic foams, Balmoral has developed a family of pure syntactic materials to cover all requirements from the ‘commodity’ end of the market through to the lowest density, highest performance, deepest depth rating systems. Please refer to Table 2. Balmoral’s pure foam system (PFS) offers many advantages over macrosphere composite foams including very low water ingress characteristics, robustness, ease of repair and modification in the
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