On the performance of a repurposed oil and gas platform for offshore wind energy generation

In an ongoing offshore energy transition period underway, fossil fuel extraction and associated carbon emission are expected to gradually be replaced by cleaner wind and wave energy generation alternatives. Many oil and gas platforms have reached or are nearing their end of useful life. In an earlier study, we addressed the feasibility of sustainable reuse of such platforms for wind energy generation instead of dismantling them. Such a re-purposing was evaluated using a fatigue reliability-based framework, along with cost considerations. In the present study, we further examine short-term fatigue across different environmental conditions using OpenFAST time-domain simulations. Axial stresses at four different locations of the platform during the repurposed phase (with a wind turbine) platform are simulated for nine representative sea states, with a focus on fatigue damage estimates in these sea states. Additionally, this work is focusing on assessing the feasibility of repurposed platform under extreme sea states. From our studies, we find that a location low in the leg of the platform is most critical when evaluating fatigue as well as ultimate limit states. Sea states associated with high wind speeds contribute to greater fatigue damage because of fluctuations in the wind loading and resonance response characteristics. These insights will be valuable for structural retrofit strategies and reuse planning.