Sub-sea pumping system and an associated method including pressure compensating arrangement for cooling and lubricating fluid

A sub-sea pumping system connected to a wellhead for pumping an effluent comprising:

• a sub-sea module comprising:
• a submerged pump connected to said wellhead for said pumping of said effluent at a predetermined pump pressure,
• a submerged electrical canned motor unit including a housing connected to said pump for operating said pump,
• single medium means for delivering a single medium fluid to said submerged pump and said submerged electrical canned motor unit for cooling and lubricating said pump and said motor unit,
• a submerged pressure compensator means located adjacent to at least said pump and said canned motor outside the housing of the submerged electrical canned motor, in fluid flow communication with the submerged pump and the submerged electrical canned motor, including a bellows assembly responsive to said pump pressure, and including means for pressurizing said single medium fluid at a pressure above said pump pressure for conveying said single medium fluid through said submerged pump and said submerged electrical canned motor, and
• a submerged heat exchanger means associated with said bellows assembly of said submerged pressure compensator means for removing the heat from said single medium fluid and transferring said heat into the surrounding sea water,
• a topside module comprising:
• a power supply means and control system for supplying electrical power to said sub-sea module, and
• a single medium supply source for supplying said single medium fluid to said single medium means, and
• umbilical feed connection means for connecting said topside module to said sub-sea module for delivering said electrical power to said submerged electrical canned motor and for delivering said single medium fluid to said sub-sea module,
• said single medium being compatible with said effluent.

In a method of pumping an effluent from a seabed well, the steps comprising:

• providing a submerged pump connected to said wellhead for pumping said effluent at a predetermined pump pressure,
• providing a submerged electrical canned motor unit including a housing for operating said pump unit,
• supplying a single medium fluid through said submerged pump and said submerged electrical canned motor for cooling and lubricating said pump and said electrical canned motor,
• providing a submerged compensator means outside the housing of the submerged electrical canned motor, in fluid flow communication with the submerged pump and the submerged electrical canned motor, and responsive to said pump pressure for pressurizing said single medium fluid at a pressure above said pump pressure for conveying said single medium fluid through said submerged pump and said submerged electrical canned motor, and selecting said single medium fluid to be compatible with said effluent.