The Reactive Flex-Joint (RFJ) is a nitrogen gas torsion springfully integrated in the LMRP-BOP stack. Its purpose is to reduce the dynamic loads and the fatigue damage applied to wellheads during drilling operations. The system achieves the reduction by applying a bending moment opposing and inverting the bending moment at the Lower Flex-Joint (LFJ). The RFJ is continuously monitored by the WAMS measurement system.
The second generation RFJ has been extensively tested in a full scale workshop test rig before being shipped offshore for a year of operations on two semi-submersible rigs operating in the North Sea/Barents Sea. This paper demonstrates by calculation and measurement that the RFJ is capable of reducing wellhead loads by more than 50% and the wellhead fatigue by more than 95%. The accuracy of the measurement system is discussed.