Mid-Water Flowline Integrity Monitoring Strategy

Mid-water flowlines are a more efficient way of product transfer between floating facilities in deepwater, with flow assurance benefits compared to traditional risers and seabed flowlines. However, the design process for mid-water flowlines is complex as these flowlines are subjected to both environment and vessel loading. During the operational phase, changes in vessel offsets, fluid composition or uncertainties in environmental data and vessel motion characteristics may lead to increased loads and escalated risk of failure. Various mid-water flowline configurations have been considered and the design issues such as strength and fatigue are discussed for each configuration. This paper also outlines an integrity monitoring strategy for mid-water flowlines to track system performance and manage the risk. A case study of such a monitoring system deployed on a mid-water flowline is also presented. This paper also discusses the methodology through which certain Key Performance Indicators (KPIs) are obtained to effectively manage the inspection intervals, and enable pre-cognition to trigger repair or remedial measures. The benefits of using a combined approach of monitoring and inspection to ensure integrity, improve operational efficiency, and develop cost-effective inspection regimes for mid-water flowlines are also presented.