MUltiphase Flow-induced Fluid-flexible structure InteractioN in Subsea applications (MUFFINS)

The MUFFINS project assembles a multidisciplinary team from Newcastle University, Imperial College London, University of Glasgow, industrial partners including BP, Chevron, TOTAL and Forsys Subsea, who are members of the Transient Multiphase Flow and Flow Assurance Consortium, Wood Group, Xodus Group, Orcina and TNO in the Netherlands, and an academic partner, the National University of Singapore, to develop the next generation of pioneering technologies and cost-efficient tools for the safe, reliable and real-life designs of subsea systems (pipelines, risers, jumpers and manifolds) transporting multiphase hydrocarbon liquid-gas flows. This world-leading academia-industry collaboration will be the first of its kind to strengthen the UK international competitiveness in multiphase flow designs for offshore oil and gas applications.

The proposed framework will specifically address fundamental and practical challenges in areas of internal multiphase flow-induced vibration (MFIV), in combination with external flow vortex-induced vibration (VIV), whose fatigue damage effects due to complicated fluid-structure interaction mechanisms can be catastrophic and result in costly production downtime. From a practical viewpoint, liquid-gas slug flows induced by the pipe geometry, seabed topography or thermo-physic-hydrodynamic instability, are common and problematical. Such flows have a highly complex hydrodynamic nature as the different mechanical properties of the deformable and compressible phases cause spatial and temporal variability in the combination and interaction of the interfaces. Subsea layout architecture, operational lifetime and environmental conditions can all affect the flow-pipe interaction patterns. Nevertheless, reliable practical guidelines and systematic frameworks for the response, stress and fatigue assessment of subsea structures undergoing MFIV are lacking. Greater complexities and unknowns arise when designing these structures subject to combined MFIV-VIV. Through an integrated programme combining modelling, simulation and experiment, high-fidelity three-dimensional computational fluid dynamics will be performed and a hierarchy of innovative and cost-efficient reduced-order models will be developed to capture vital multiple MFIV and VIV effects, providing significant insights into detailed flow features and fluid-structure coupling phenomena. Validation, verification, uncertainty and reliability analyses will be carried out by comparing numerical results with experimental tests and industrial data to improve confidence in identifying the likelihood of fatigue failure and safety risks. Computationally-efficient tools and open-source codes will be advanced and utilised by industry and worldwide researchers. The project will minimise uncertainties in MFIV-VIV predictions associated with multi-scale multi-physics fluid-elastic solid interactions, ultimately delivering improved design optimisation and control of the most efficient multiphase flow features.

The UK oil and gas industry has been at the heart of the UK prosperity for five decades but has faced significant challenges recently. In October 2016, the UK Government founded the Oil & Gas Authority to safeguard collaboration, maximise resource recovery from the UK Continental Shelf, and maintain the UK competitiveness with future investments. In alignment with these strategies, the MUFFINS project will deliver the maximum benefits to and security of global oil and gas energy by means of cutting-edge technologies, cost-efficient tools and recommended guidelines to significantly improve the integrity, reliability and safety of subsea systems transporting multiphase flows. The project will upskill the next-generation engineers and scientists in the oil and gas sector. The technical know-how and deliverables will lead to a transformative improvement in structural designs and reduction of environmental impacts, operational and maintenance costs.

The impact of this research will be significant on a global scale. Numerous oil and gas fields are being identified, operated and developed across deep-water oceans, and in the 21st century, subsea tieback technologies connecting new fields to existing facilities through long-distance pipelines to extend the life of production infrastructure are also becoming increasingly viable, both technically and economically. These technologies pose technical difficulties associated with liquid-gas slug flow occurrences and potential multiphase flow-induced vibrations (MFIV). The UK Health and Safety Executive reported that up to 21% of the topside piping networks on oil and gas production platforms have been affected by internal flow-induced vibrations, making it the second largest cause of fatigue failure. For subsea systems, issues around multiphase flows have also recently come to light for subsea jumpers, pipelines and risers. This project will allow a better understanding of MFIV phenomena and their potential effects in addition to and in combination with other environmental factors.

Subsea and flow assurance engineers, consultants and operators who are involved in analysis, design, manufacture, decision-making and operation of subsea systems transporting multiphase flows will significantly benefit from our game-changing technologies which will enable them to perform a smarter, environmentally safer, more reliable and cost-efficient design. With anticipated flow rates, forces and pressure drops, accurate pipe sizing will be sufficient to transport the mixture and accommodate future production change as oil and gas fields mature. With realistic flow regime identification in an oscillating pipe, precise estimation of temperature/pressure variations at different locations will allow the prevention of hydrate and paraffin formations, enhance the flow assurance and help operators decide whether expensive insulations or chemical inhibitors are needed. With improved assessments of dynamic loads, structural engineers can elucidate MFIV-induced fatigue, enabling them to decide whether a time-consuming detailed analysis is required. Costs for developing a subsea separation technology presently expensive for implementation in deep waters could be significantly reduced with an enhanced understanding of multiphase flows and MFIV. Better prediction accuracy of transient flows will allow the improved designs of longer pipelines, hence reducing the amount of processing required offshore and increasing operational safety.

This project will produce upskilled UK-based experts in subsea, mechanical, civil and chemical engineering who will benefit from working with the interdisciplinary research teams. All researchers will receive training in mathematical modelling, numerical techniques, managing data, public engagement and knowledge exchange. In addition, they will engage in teaching activities including tutorials, software tool demonstrations and co-supervisions of theses. These opportunities will enable effective professional competencies towards future long-term employability aspects. New numerical-experimental results will serve as invaluable benchmarks for other modellers and code developers. The experimental setup will inspire other experimental campaigns, and multidisciplinary skills of staff and lab technicians will be enhanced. Private and public sector researchers will be able to carry out related proof-of-concept tests which will improve the project public visibility.

The involvement of industry will ensure that our objectives and commitments remain focused on aspects of practical importance, whilst still answering fundamental questions and discovering new multiphase fluid dynamic phenomena. The UK economic competitiveness stands to be enhanced through this collaborative project, with the potential to attract more international consultancy jobs and investment from other companies leading to new joint industrial projects.