As the exploration for oil and gas is shifting towards greater water depths, there is a market for subsea rock installation (SRI) at these large water depths as well. Boskalis is a key player in the rock installation market and installing rock material at water depths of approximately 3000 meters is still far from routine work. Therefore, Boskalis is researching accurate and cost-efficient systems for installing rocks in these ultra-deep waters.
Since this is a concept with operations that are not applied before by Boskalis, there are no structural test data available that could be used for research purposes. Therefore, it is decided to perform scaled model tests to obtain reliable production rates of the rock installation process. The basket and its corresponding release mechanisms is built on scale and forces are measured during the release process for different configurations, where the type of release mechanisms and the area of opening were varied. The production rates that followed from these force measurements are used as input parameter in the model that simulates the dynamic response of the envisaged concept.
In order to better understand the force and motion behaviour of this envisaged concept, a simplified one-dimensional cable model has been constructed in Matlab to simulate the dynamic response of the lifting wire and basket, and the force distribution in the lifting wire.