System and method for multiphase pump lubrication
A subsea system includes a multiphase pump, configured to transfer a multiphase fluid and a multiphase separator, configured to separate the multiphase fluid into solid, liquid, and gaseous phases. The multiphase separator includes a solid-liquid separation device, which is configured to facilitate separation of the solid phase and the liquid phase from the multiphase fluid. The multiphase separator includes a gas-liquid separation device, which is configured to facilitate separation of the gaseous phase and the liquid phase from the multiphase fluid. The multiphase separator includes a liquid reservoir, which is configured to contain a volume of the liquid phase to be used as a lubricant for the multiphase pump. Finally, the multiphase separator includes a liquid outlet, which is configured to transfer the liquid phase from the liquid reservoir to the multiphase pump.
1. A subsea system, comprising:
a multiphase pump, configured to transfer a multiphase fluid; and
a multiphase separator, configured to separate the multiphase fluid into solid, liquid, and gaseous phases, comprising:
a multiphase fluid inlet coupled to a shell, wherein the multiphase fluid inlet is configured to receive the multiphase fluid from the multiphase pump;
a solid-liquid separation device disposed in the shell, wherein the solid-liquid separation device is configured to facilitate separation of the solid phase and the liquid phase from the multiphase fluid;
a gas-liquid separation device disposed in the shell, wherein the gas-liquid separation device is configured to facilitate separation of the gaseous phase and the liquid phase from the multiphase fluid;
a liquid reservoir disposed in the shell, wherein the liquid reservoir is configured to hold a volume of the liquid phase to be used as a lubricant for the multiphase pump; and
a liquid outlet coupled to the shell, wherein the liquid outlet is configured to transfer the liquid phase from the liquid reservoir to the multiphase pump.
2. The system of claim 1 , wherein the shell of the multiphase separator is configured with a height greater than a width.
3. The system of claim 1 , wherein the solid-liquid separation device comprises a baffle oriented at an angle from a longitudinal axis of the multiphase separator.
4. The system of claim 3 , wherein the angle between the baffle and the longitudinal axis of the multiphase separator is less than approximately 45 degrees.
5. The system of claim 3 , comprising a gas vent coupled to the baffle, configured to enable the gas phase to vent from under the baffle.
6. The system of claim 1 , wherein the solid-liquid separation device comprises a vortex breaker.
7. The system of claim 1 , wherein the gas-liquid separation device comprises an upwardly-facing outlet nozzle.
8. The system of claim 1 , wherein the shell is configured to operate at a subsea pressure.
9. The system of claim 1 , comprising,
a solid outlet coupled to the shell, wherein the solid outlet is configured to remove the solid phase from the multiphase separator; and
a gaseous outlet coupled to the shell, wherein the gaseous outlet is configured to remove the gaseous phase from the multiphase separator.
10. The system of claim 9 , comprising an eductor coupled to the solid outlet and the gaseous outlet, configured to aspirate the solid phase using the gaseous phase.
11. A subsea system, comprising:
a multiphase separator, configured to separate a multiphase fluid into solid, liquid, and gaseous phases, comprising:
a multiphase fluid inlet coupled to a shell, wherein the multiphase fluid inlet is configured to receive the multiphase fluid;
a solid-liquid separation device disposed in the shell, wherein the solid-liquid separation device is configured to facilitate separation of the solid phase and the liquid phase from the multiphase fluid;
a gas-liquid separation device disposed in the shell, wherein the gas-liquid separation device is configured to facilitate separation of the gaseous phase and the liquid phase from the multiphase fluid;
a liquid reservoir disposed in the shell, wherein the liquid reservoir is configured to contain a volume of the liquid phase to be used as a lubricant for a pump; and
a liquid outlet coupled to the shell, wherein the liquid outlet is configured to transfer the liquid phase from the liquid reservoir to the pump.
12. The system of claim 11 , wherein the solid-liquid separation device comprises a baffle oriented at an angle from a longitudinal axis of the multiphase separator.
13. The system of claim 11 , wherein the liquid outlet is configured to couple with bearings or timing gears of the pump.
14. A method of operating a subsea system, comprising:
transferring a multiphase fluid from an outlet of a multiphase pump to an inlet of a multiphase separator;
facilitating separation of a solid phase and a liquid phase from the multiphase fluid using a solid-liquid separation device disposed in a shell of the multiphase separator;
facilitating separation of a gas phase and the liquid phase from the multiphase fluid using a gas-liquid separation device disposed in the shell of the multiphase separator;
maintaining a volume of the liquid phase in a liquid reservoir disposed in the shell of the multiphase separator;
transferring the liquid phase from the liquid reservoir to lubricated components of the multiphase pump; and
lubricating the lubricated components of the multiphase pump with the liquid phase.
15. The method of claim 14 , wherein the volume of the liquid phase maintained in the liquid reservoir enables the multiphase pump to operate for a time period during which the multiphase fluid has no liquid phase by supplying the liquid phase to the lubricated components of the multiphase pump.
16. The method of claim 14 , wherein the separation of the solid phase, the liquid phase, and the gaseous phase from the multiphase fluid is performed passively with no moving parts in the solid-liquid separation device or the gas-liquid separation device.