An effective long distance deepwater subsea tieback development requires thorough consideration of the flow assurance challenges which could potentially arise due to the extreme distance and depth. In most cases, this effort encompasses thermo-hydraulic design of the whole production system for each phase in the life of the development. The approach adopted in this paper focuses on assessing the minimum slug free rate in flowlines. Slugging in flowlines mounted on sleepers has the potential to impact integrity as a result of fatigue. Therefore, slug free rate assessment is a critical step for the development of a safe, effective and economical operating philosophy for a long distance deepwater tie-back. This paper highlights the application of various simulation techniques used in the determination of the minimum slug free rate for a gas condensate system, accounting for relevant uncertainties that could impact slugging, systems stabilities and pipeline fatigue issues. High resolution modeling of the bathymetry, particularly at the sleeper positions, together with a systematic and novel simulation approach using steady state analysis, transient simulation and slug tracking analysis were used to determine a realistic minimum slug free rate of the production system over field life. In depth and systematic evaluation was carried out using flow regime indicator and rigorous transient simulation techniques; i.e. assessment of flow and pressure instabilities at key locations along the production system and tracking the development and movement of a liquid slug along the subsea flowline.
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