Operational Scour Management for Safe Jack-Up Operations

Scour is an imminent threat for jack-up operations in shallow waters with sandy seabed conditions, strong tidal currents and/or a harsh wave climate, such as the North Sea. Jack-up operations in scour-sensitive areas require jack-up operators to evaluate the risk of scour and to adapt a scour management strategy in order to safeguard against foundation failure. Jack-up deployments are characteristically short term operations. This can be in the range of one day (construction project jack-ups) to several months (drilling units). Often, the strategy is to monitor scour and take remedial measures if and when required. An operational scour forecast and hindcast system was developed in order to assist jack-up operators with their management of scour. The system is based on automated importing and processing of metocean data (water levels, waves and currents) from operational metocean models or measurement stations and calculating forecasts for the temporal scour development with semi-empirical relations, derived from physical model tests for various types of foundations. During an operation, the results provide the basis for a periodic assessment whether, how much and where scour protection is required and when surveys should be performed. After an operation, the hindcast results serve as calibration for the scour prediction model and as evaluation of the scour management strategy.