The increase of CO2 content in produced fluids is an observed phenomenon due to natural occurrence of CO2 in the fluid composition and due to the (re)injection of CO2-rich gases for EOR purposes. Moreover, during the production in offshore fields using subsea tiebacks layouts, when low flow rates occur in a downward flowline-riser system, severe slugging is one of the most important flow assurance challenges that needs to be tackled. When severe slugging is expected to happen in a high CO2 content oil field, it is important to understand its main effects on the referred phenomenon. This work assesses how the increase of CO2 content in the reservoir fluid impacts the severe slugging behavior for a typical subsea tieback configuration. For that, 1D gas-liquid flow numerical simulations are carried out under several flow rates and GOR conditions. The general results (pressure drop, etc) are thoroughly analyzed, followed by discussions on the flow transient behavior, on the intermittence of key parameters and on the slugging frequency. Focus is given to the effects of an increasing CO2 content and interesting conclusions are drawn.

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