Systems and methods of using subsea frames as a heat exchanger in subsea boosting systems

A method of cooling a motor of an electrical submersible pump employed in an electrical submersible subsea booster pumping system, the method comprising the steps of:

• providing an electrical submersible pump assembly in a vicinity of a sea floor, the electrical submersible pump assembly including a motor and at least one pump housed within a containment vessel, the motor being filled with a dielectric lubricant and having a motor dielectric lubricant inlet port and a motor dielectric lubricant outlet port spaced apart from the motor dielectric lubricant inlet port, the containment vessel also having a dielectric lubricant inlet port and a dielectric lubricant outlet port, the electrical submersible pump assembly further including a first conduit segment extending between the motor dielectric lubricant outlet port and the dielectric lubricant outlet port in the containment vessel and a second conduit segment extending between the dielectric lubricant inlet port in the containment vessel and the motor dielectric lubricant inlet port;
• providing a subsea supporting frame structure adjacent the electrical submersible pump assembly, the subsea supporting frame structure comprising a mounting skid framing at least major portions of the electrical submersible pump assembly and comprising a plurality of elongate main structural members, each of the plurality of elongate main structural members having a fluid conduit extending along a longitudinal axis thereof and interconnected so that the fluid conduits collectively form a manifold structure, at least one of the plurality of elongate main structural members including a fluid inlet port in fluid communication with the dielectric lubricant outlet port in the containment vessel of the electrical submersible pump assembly defining a supporting frame structure fluid inlet, at least one of the plurality of elongate main structural members including a fluid outlet port in fluid communication with the dielectric lubricant inlet port in the containment vessel of the electrical submersible pump assembly defining a supporting frame structure fluid outlet, portions of the dielectric lubricant flowing along a plurality of different pathways between the fluid inlet and the fluid outlet of the supporting frame structure formed by the plurality of elongate main structural members;
• circulating dielectric lubricant from the motor dielectric lubricant outlet port to the fluid inlet of the supporting frame structure;
• removing heat from the dielectric lubricant circulating through the plurality of elongate main structural members flowing through the plurality of different pathways between the fluid inlet and the fluid outlet of the supporting frame structure, by transferring heat energy in the dielectric lubricant to seawater flowing through the subsea supporting frame structure and across outer surfaces of the plurality of elongate main structural members to thereby reduce the temperature of the dielectric lubricant;
• and
• circulating the dielectric lubricant from the outlet port of the supporting frame structure to the motor dielectric lubricant inlet port.

A system for cooling a motor of an electrical submersible pump assembly employed in an electrical submersible subsea booster pumping system, the system comprising:

• an electrical submersible pump assembly including a subsea electrical submersible pump having a motor filled with dielectric lubricant, a motor dielectric lubricant outlet port, and a motor dielectric lubricant inlet port, the motor dielectric lubricant outlet port spaced apart from the motor dielectric lubricant inlet port;
• a subsea supporting frame structure having a plurality of elongate main structural members, each of the plurality of elongate main structural members having an exterior surface substantially exposed to seawater in a subsea environment and having a main body having a fluid conduit formed at least partially therethrough along a longitudinal axis thereof, the plurality of fluid conduits and corresponding plurality of elongate main structural members connected to form a plurality of different dielectric lubricant pathways between a supporting frame structure fluid inlet and a supporting frame structure fluid outlet;
• at least one fluid conduit extending from the motor dielectric lubricant outlet port to the supporting frame structure fluid inlet to thereby form a heated dielectric lubricant discharge pathway therebetween;
• at least one other fluid conduit extending from the supporting frame structure fluid outlet to the motor dielectric lubricant inlet port to thereby form a cooled dielectric lubricant return pathway therebetween;
• a fluid moving device positioned to circulate the dielectric lubricant from the motor through the heated dielectric lubricant discharge pathway, the plurality of different dielectric lubricant pathways through the supporting frame structure, and the cooled dielectric lubricant return pathway;
• and
• wherein the electrical submersible subsea booster pumping system is deployed such that the dielectric lubricant that circulates through the supporting frame structure is cooled by the surrounding seawater.

A system for cooling a motor of an electrical submersible pump assembly employed in an electrical submersible subsea booster pumping system, the system comprising:

• an electrical submersible pump assembly including a subsea electrical submersible pump having a motor filled with dielectric lubricant, a motor dielectric lubricant outlet port, and a motor dielectric lubricant inlet port, the motor dielectric lubricant outlet port spaced apart from the motor dielectric lubricant inlet port;
• a containment vessel positioned to contain at least major portions of the electrical submersible pump assembly and having a dielectric lubricant outlet port and a dielectric lubricant inlet port;
• a subsea supporting frame structure having a plurality of elongate main structural members, each of the plurality of elongate main structural members having an exterior surface substantially exposed to seawater in a subsea environment and having a main body having a fluid conduit formed at least partially therethrough along a longitudinal axis thereof, each fluid conduit positioned in fluid communication with at least one other of a plurality of fluid conduits corresponding to the plurality of elongate main structural members, at least one of the plurality of elongate main structural members including a fluid inlet port in fluid communication with the dielectric lubricant outlet port in the containment vessel of the electrical submersible pump assembly defining a supporting frame structure fluid inlet, at least one of the plurality of elongate main structural members including a fluid outlet port in fluid communication with the dielectric lubricant inlet port in the containment vessel of the electrical submersible pump assembly defining a supporting frame structure fluid outlet, a plurality of different dielectric lubricant pathways extending between the fluid inlet and the fluid outlet of the supporting frame structure and through a corresponding different set of one or more of the plurality of fluid conduits, the plurality of different dielectric lubricant pathways configured to facilitate a transfer of heat energy in dielectric lubricant circulating through the plurality of different dielectric lubricant pathways to seawater flowing through the subsea supporting frame structure and across outer surfaces of the plurality of elongate main structural members to thereby reduce temperature of the dielectric lubricant;
• at least one fluid conduit extending between the motor dielectric lubricant outlet port and the supporting frame structure fluid inlet to thereby form a heated dielectric lubricant discharge pathway therebetween;
• at least one fluid conduit extending between the supporting frame structure fluid outlet and the motor dielectric lubricant inlet port to thereby form a cooled dielectric lubricant return pathway therebetween;
• and
• a fluid moving device positioned to circulate dielectric lubricant for the motor through the heated dielectric lubricant discharge pathway, the plurality of different dielectric lubricant pathways through the supporting frame structure to be cooled by seawater when deployed therein, and the cooled dielectric lubricant return pathway.