Study on the stress variation in the components of offshore rig legs in various collision situations

Résumé

The offshore rigs are designed for oil and gas drilling and extraction in the seabed. Generally speaking, an offshore structure consists of its body and support elements (legs). As a result of the interaction of the legs with the environment, or the collision with various floating objects, some damage may affect the components. In this case, a methodology should be found, in order to determine the strains occurring in such situations. The paper studies the behavior of offshore rig legs’ elements in various cases of damage to the components. The Finite Element Method is used to determine the strain state in various damage scenarios. As offshore structures operate in the marine environment, which displays a dynamic behavior, calculations were performed to detect the alterations of the rig’s own pulsations. It is important for the operators of the drilling installations as it avoids the overlap of the rig’s own vibration modes.