Patent ID: 11946472
Assignee: HALLIBURTON ENERGY SERVICES, INC.
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  E | IPC E  F

Claim 9:
10. A method of lifting liquid in a wellbore, comprising:
running an electric submersible pump (ESP) assembly into a wellbore, wherein the ESP assembly comprises
an electric motor having a first drive shaft,
a seal section coupled at an upstream end to a downstream end of the electric motor having a second drive shaft coupled to the first drive shaft,
a charge pump assembly disposed downstream of the seal section, wherein the charge pump assembly comprises
a third drive shaft coupled to the second drive shaft,
a first fluid mover mechanically coupled to the third drive shaft and having a fluid inlet and a fluid outlet,
a fluid reservoir concentrically disposed around the third drive shaft and located downstream of the first fluid mover, wherein an inside surface of the fluid reservoir and an outside surface of the third drive shaft define a first annulus that is fluidically coupled to the fluid outlet of the first fluid mover, wherein the third drive shaft is not radially supported within the first annulus, wherein when the separator drive shaft is about 0.6875 inches in diameter, the first annulus has a volume of at least 70 cubic inches and less than 100 cubic inches, when the separator drive shaft is about 0.875 inches in diameter, the first annulus has a volume of at least 85 cubic inches and less than 120 cubic inches, when the separator drive shaft is about 1.0 inches in diameter, the first annulus has a volume of at least 180 cubic inches and less than 250 cubic inches, and when the separator drive shaft is about 1.1875 inches in diameter, the first annulus has a volume of at least 220 cubic inches and less than 300 cubic inches, and
a second fluid mover mechanically coupled to the third drive shaft and having a fluid inlet and a fluid outlet, wherein the second fluid mover is located downstream of the fluid reservoir, and wherein the fluid inlet of the second fluid mover is fluidically coupled to the first annulus,

a gas separator assembly coupled at an upstream end to a downstream end of the charge pump assembly, having a fourth drive shaft coupled directly or indirectly to the third drive shaft and having an inlet in fluid communication with an outlet of the charge pump assembly, having a gas flow path and liquid flow path separator having a gas phase discharge port open to an exterior of the gas separator assembly and a liquid phase discharge port,
an inverted shroud coupled at an uphole end to the gas separator assembly or to the charge pump assembly and coupled at a downhole end to the ESP assembly downhole of the charge pump assembly, and
a production pump assembly coupled at an upstream end to a downstream end of the gas separator assembly and having an inlet in fluid communication with the liquid phase discharge port of the gas flow path and liquid flow path separator;

turning the third drive shaft of the charge pump assembly by the electric motor;
drawing reservoir fluid from the wellbore into the charge pump assembly by the first fluid mover;
moving the reservoir fluid downstream by the first fluid mover within the charge pump assembly;
filling the first annulus within the charge pump assembly with the reservoir fluid;
flowing the reservoir fluid from the first annulus to the fluid inlet of the gas separator assembly;
discharging a first portion of the reservoir fluid via the gas phase discharge port to an exterior of the gas separator assembly;
discharging a second portion of the reservoir fluid via the liquid phase discharge port to the inlet of the production pump assembly;
pumping the second portion of the reservoir fluid by the production pump assembly, and
flowing the second portion of the reservoir fluid out of a discharge of the production pump assembly and via a production tubing to a surface location.