As facilities in the Dutch North Sea are approaching the end of their production life, the focus shifts from the developing to the decommissioning of facilities. The legislation on offshore pipeline decommissioning in the Dutch North Sea is currently unclear. The Minister can dec
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As facilities in the Dutch North Sea are approaching the end of their production life, the focus shifts from the developing to the decommissioning of facilities. The legislation on offshore pipeline decommissioning in the Dutch North Sea is currently unclear. The Minister can decide whether pipelines are to be removed or are allowed in situ. In situ decommissioning is considered unwanted by major external stakeholders. Besides, the pipeline owner holds an extensive liability for the pipeline after decommissioning. Full removal options, on the other hand, are accompanied with large environmental, technical and financial impact. This graduation thesis Accelerated pipeline degradation aims to investigate how accelerated degradation of steel can contribute to offshore pipeline decommissioning. By accelerated degradation it is aspired to limit the environmental impact and seabed disturbance. Furthermore, the costs and technical impact can be reduced. After evaluating the current decommissioning methods, a series of alternative options is assessed. The assessment has resulted in a further investigation of galvanic corrosion for steel degradation. With this investigation, it is aspired to evaluate the mechanism of galvanic corrosion to accelerate the corrosion of the steel pipeline. By doing so, the liability period at the sea bottom would decrease dramatically with respect to in situ decommissioning. The materials that could be applicable for galvanic coupling were considered. Due to its high standard potential and low costs, the use of graphite (carbon) is determined to be most suitable. Subsequently, several small-scale tests on low carbon steel. In a laboratory setting the galvanic corrosion of steel was investigated by coupling steel samples to carbon electrodes. Coupling with platinum electrodes is also tested to provide reference scenarios. The results of the tests show an increase of corrosion current with addition of a galvanic couple. However, with increasing cathodic surface the steel dissolution is limited by corrosion kinetics and diffusion limitations. A preliminary schematisation for implementation is designed. Accordingly, the main challenges are identified. The test results and identified challenges are the motivation for a field test. This field test is to be designed to investigate the potential feasibility issues that arise in the practical situation. Furthermore, the operational challenges can be addressed on the test site.