Barrier fluidless subsea pump for subsea seawater desulphation process
Within the industrialisation program of Springs, an innovative, all electric, subsea seawater desulphation & injection technology, the requirement for using Barrier Fluidless subsea pump was identified.
In conventional subsea pumping technology, barrier fluid is used to lubricate, cool and provide an insulation barrier to the electric motor. There are two negative aspects of using barrier fluids:
1 – A continuous supply of barrier fluid must be ensured through the umbilical from topside: this substantially increases the cost of the umbilical
2 – Leakage of barrier fluid into the process water can be detrimental to the downstream process
Saipem and Curtiss Wright have qualified a subsea pumping system lubricated and cooled using only the pumped fluid, allowing to eliminate the need for barrier fluid. The system leverages on the seal-less canned motor pump technology, which has been successfully deployed for more than 70 years in various critical applications where reliability is paramount.
A full-scale, 3.0 MW prototype was designed, manufactured and wet-pit-tested to demonstrate a Technology Readiness Level (TRL) of 4 per API 17Q.
In addition to verification of basic pump performance across the entire operating speed range, numerous other system testing was performed. The testing campaign included operation at reduced, normal, and over-speed conditions, emergency shutdown, coast-down, and endurance runs at full-load.
Canned motor technology is significantly scalable and flexible, with demonstrated reliability in topside applications up to 5.5 MW in operation, multi-phase fluid pumping, fluids with highly abrasive solids, and design life measured in decades.
Subsea Gas dewpointing: a solution to improve production of subsea gas fields.
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.
Riccardo Giolo
Riccardo is a Mechanical Engineer graduated at university of Padua with more than 15 years’ experience in offshore oil & gas. Currently managing projects within the Sonsub Subsea Factory division in Saipem, he began his career on the pipeline inspection and remote repair projects as technical coordinator, project manager and finally department manager. Before moving to the Subsea Factory, he also held the position of Tendering Manager for all Sonsub Initiatives.
