Seabed scour often occurs at the bottom of jacket legs and as such, the mudmats are no longer sitting on the seabed and providing support. This is especially true for welded crown shim connections. Hydrodynamic loading can cause the jacket to move about the driven piles, and is felt in the steel platform and topside. This movement can lead to a reduced life expectancy of the jacket if it is not rectified.
FoundOcean has stabilised many North Sea jackets with a two-stage grouted solution. A donut-shaped fabric formwork is installed and grouted under and around each mudmat. The grout bag acts as a support for the mudmat and as a grout seal for the leg pile annulus. After the grout in the formwork has cured, the remaining void is filled with grout to ensure even weight distribution. Next, grout is injected into the leg pile annuli to strengthen the welded connection and eliminate jacket movement.