Where pipelines, cable and subsea structures are installed in fast running waters, and cohesionless soils make up the seabed, excessive scour can create serious structural or operational problems.
Seabed scour and has the potential to form sand waves, seabed erosion and deposition of material dependent on the near seabed changes in water particle velocity.
In the context of offshore structures scour can be caused when an installation interferes with the natural near seabed water particle velocities.
Pipelines can cause water to accelerate in front of the pipeline thus eroding the soil in front and in extreme cases creates a breakthrough under the pipeline to cause free-spans with the obvious undesirable consequences. Mono-piles cause the water to accelerate around them, creating a scour hole around the base.
Where our Scour Prediction Analysis indicates the need, we can supply a range of scour protection, scour remediation and free span correction products.
Scour can occur in a surprisingly short amount of time. In fast-running waters with granule solid, excessive scour can create serious structural voids, leading to excessive free spans, excessive pile exposure or other structural problems.
Pipeshield can supply bulk aggregates in special subsea rated bulk bags. A simple filling of scour holes, free-spans and supports can be carried out using sand and grout bags
Pipeshield design and manufacture a wide range of concrete mattresses to give your subsea installations the best possible protection.
Pipeshield’s Precise Rock Placement Units (PRP’s) are designed for easy handling via a single point lift, optimising handling and installation time.
The Geo-Mat geotextile mattress has been designed to provide extra benefits to those obtained from a normal concrete mattress. The highly durable, needle punch non-woven layer can be used as a preventative measure to avoid sinking in soft sea or river bed conditions or used as an anti-abrasive layer to provide a barrier between the concrete mattress and the asset.
A standard Geo-Mat comes in an oversized 6m x 3m size designed to be installed with our standard range of mattresses, although bespoke sizes and specifications are also available.
With easy fixing points at all loops, the pre-fixed Geo-Mat enables a single process installation of both concrete mattress and protective layer. The Geo-Mat can be fitted to the top, bottom or both sides of the concrete mattress.
Pipeshield has previously, in conjunction with HR Wallingford and Fugro Ltd, carried out in depth Scour Studies for Shell to establish scour potential and provide preventative measures on the Carrack and Cutter fields. Computer CFD models were created and tested against measured data to establish site specific scour benchmarks in order to predict and thus prevent scouring in the two southern North Sea locations using fronded concrete mattresses.