For long gas subsea tie-back applications, removing liquids and condensable components from gas prior to its export allows to extend field lifetime and improve operability of export line(s).
Indeed, for subsea gas fields located far from shore and/or at high water depths, the main reasons of premature stop of production are the lack of available pressure and the operability issues due to liquid accumulation. By removing liquid and components that can condensate in the export line(s) prior to the export, the gas production is improved (reduction of pressure drops, no risk of hydrate or wax formation, no liquid accumulation).
For this purpose, SAIPEM has developed a subsea station performing gas dewpointing to remove as much as possible liquids and condensables from the production gas coming from wells. The gas coming out of the station is exported alone in the export line(s) while the liquids and condensable components are exported to shore via a dedicated line.
This station is mainly based on mature and very low power consuming components. The station can be implemented on greenfield cases to simplify the pipeline architecture in suitable cases (reduction of export lines number, easier operability, etc…) or advantageously in brownfield configurations to extend field life (by reducing the pressure drops and liquid accumulation issue). This paper presents several case studies showing how the solution can improve production in case of brownfields applications. This solution could be one of the keys to maximize gas fields production in the future.