Hydrate management strategy of most of the latest deepwater developments relies mainly on prevention because of the inherent difficulty to deploy remediation procedures. For subsea developments relying on passive insulation, Christmas trees, manifolds, flowlines and risers are designed with thermal insulation which provides sufficient time to implement on adequate operational procedure (depressurisation / methanol flushing or crude oil displacement with dead oil). The later strategy aims at eliminating the hydrate formation risk in the production network for extended shut-down periods and facilitating production restart procedures. During the commissioning activity on the field, the thermal performance of the production system can be tested and compared to the thermal performance specification through specific procedures and measurements. Components with degraded insulation performance have measurable effects even when they have a limited surface area. When it is feasible, corrective actions can be implemented on the system to improve their insulation performance, the main difficulty being to locate the cold spots with accuracy. This paper presents the application of Computational Fluid Dynamics (CFD) as a tool to evaluate the impact of cold spots and convection heat transfers on the thermal performance of typical deepwater field of West Africa. The thermal modelling approach during the detailed design, the results of the thermal tests during the commissioning and investigation of potential cold spots through thermal modelling are developed.
展开▼
