Awareness of the challenge with lower available Wellhead fatigue life has increased as the Oil and gas industry has gained more knowledge through advanced analysis and tests. Loads on Wellhead are influenced by movements from drilling rig transferred through Marine Riser and BOP. These loads cause cyclical bending moments and Wellhead fatigue degradation. The intention of Reactive Flex-Joint (RFJ) is to lower the fatigue damage by reducing cyclical bending moment, which is a main contributor for Wellhead fatigue.
It's was built a technology demonstrator (scale 1:25) in 2006 and patent of the system was approved. Later a full-scale workshop test model was constructed including a Flex-Joint (FJ) for simulation of environmental conditions. In addition there were preformed thousands of transient dynamic simulations with irregular sea conditions. An independent company duplicated these analyses and all results are verified by 3rd party. The 3rd party company also approved product qualification and use before offshore deployment. An environmental test through a complete drilling campaign of a new well was preformed spring 2016, verified the technology and efficiency covering a wide variety of environmental conditions. The BOP was instrumented to monitor live bending moments and inclination with and without the RFJ. More than 50 subsea tests proved 55 - 65% reduction of cyclical bending moment meaning 10 - 15 times extension of the remaining Wellhead fatigue life. The conclusion is that a modified FJ can reduce dynamic bending moments transferred from Riser to Wellhead during drilling and Work-Over operations. Reduced fatigue exposure gives increased Well access, improved Well Integrity and significant extended Wellhead fatigue life. The reduction of cyclical bending moments on Wellhead give extension of available days for connection, enabling additional Workover and/or side track drilling resulting in Increased Oil Recovery.
