Electric Submersible Pump (ESP) Gas Slug Processor and Mitigation System

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 motor drive shaft, a seal section having a seal drive shaft coupled to the motor drive shaft, a gas separator assembly having a separator drive shaft coupled to the seal drive shaft,
• a fluid reservoir concentrically disposed around the separator drive shaft, wherein an inside surface of the fluid reservoir and an outside surface of the separator drive shaft define a first annulus within a portion of the fluid reservoir that does not enclose a radial support of the drive shaft, 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;
• wherein 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;
• wherein 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 wherein 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,
• a first fluid mover having a second fluid inlet and a second fluid outlet, wherein the first fluid mover is located downstream of the fluid reservoir, and
• wherein the second fluid inlet is fluidically coupled to the first annulus, a separation chamber concentrically disposed around the separator drive shaft and located downstream of the first fluid mover, wherein an inside surface of the separation chamber and the outside surface of the separator drive shaft define a second annulus that is fluidically coupled to the second fluid outlet, and
• a crossover defining a gas flow path and liquid flow path separator having a gas phase discharge port open to an exterior of the assembly and a liquid phase discharge port, wherein the crossover has a third fluid inlet that is fluidically coupled to the second annulus,
• and a centrifugal pump assembly having a pump drive shaft coupled to the separator drive shaft and a fourth fluid inlet fluidically coupled to the liquid discharge port of the crossover of the gas separator assembly;
• turning the separator drive shaft by the electric motor of the ESP assembly;
• drawing reservoir fluid from the wellbore into the gas separator assembly;
• filling the first annulus with the reservoir fluid;
• flowing the reservoir fluid from the first annulus to the first fluid mover moving the reservoir fluid downstream by the first fluid mover to the crossover;
• discharging at least some of the gas phase fluid portion of the reservoir fluid via the gas phase discharge port of the crossover to an exterior of the gas separator assembly;
• discharging at least some of the liquid phase portion of the reservoir fluid via the liquid phase discharge port of the crossover to the centrifugal pump assembly;
• pumping the portion of the reservoir fluid discharged via the liquid phase discharge port by the centrifugal pump assembly;
• and
• flowing the portion of the reservoir fluid discharged via the liquid phase discharge port out a discharge of the centrifugal pump assembly via a production tubing to a surface location.

A method of assembling an electric submersible pump (ESP) assembly at a wellbore location, comprising:

• coupling a downstream end of an electric motor to an upstream end of a seal unit;
• lowering the electric motor, and seal unit partially into the wellbore;
• coupling a downstream end of the seal unit to an upstream end of a gas separator assembly, wherein the gas separator assembly comprises
• a drive shaft,
• a fluid reservoir concentrically disposed around the drive shaft, wherein an inside surface of the fluid reservoir and an outside surface of the drive shaft define a first annulus within a portion of the fluid reservoir that does not enclose a radial support of the drive shaft, 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;
• wherein 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;
• wherein 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 wherein 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;
• a first fluid mover having a fluid inlet and a fluid outlet, wherein the first fluid mover is located downstream of the fluid reservoir, and wherein the fluid inlet of the first fluid mover is fluidically coupled to the first annulus;
• a separation chamber concentrically disposed around the drive shaft and located downstream of the first fluid mover, wherein an inside surface of the separation chamber and the outside surface of the drive shaft define a second annulus that is fluidically coupled to the fluid outlet of the first fluid mover;
• and
• a crossover defining a gas flow path and liquid flow path separator having a gas phase discharge port open to an exterior of the assembly and a liquid phase discharge port, wherein the gas flow path and liquid flow path separator has a fluid inlet that is fluidically coupled to the second annulus;
• lowering the electric motor, seal unit, and gas separator assembly partially into the wellbore;
• coupling a downstream end of the gas separator assembly to an upstream end of a centrifugal pump assembly;
• and
• lowering the electric motor, seal unit, gas separator assembly, and centrifugal pump assembly partially into the wellbore.