Systems and Methods for Transmission of Electric Power to Downhole Equipment

• US 20120319474A1
• Filed: 06/14/2011
• Published: 12/20/2012
• Est. Priority Date: 06/14/2011
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Chung, Cameron K.
• Granted Patent: US 8,624,530 B2
• Time in Patent Office: Days
• US Class Current: 307/17
• CPC Class Codes: H02J 3/1878 using tap changing or phase shifting transformers
• CPC Class Codes: H02J 3/1892 the arrangements being an integral part of the load, e.g. a motor, or of its control circuit
• CPC Class Codes: Y02E 40/30 Reactive power compensation

Abstract

Systems and methods in which output power that would conventionally be provided by surface equipment to drive downhole equipment, is transformed to increase the voltage before transmitting the power over a power cable to downhole equipment. The downhole equipment includes a step-down transformer that receives power from the power cable at a voltage which is too high to drive the motor or other downhole equipment and reduces the voltage to a level that is suitable for use by the downhole equipment. The step-down transformer may utilize toroidal transformers that are positioned around other components of the system, such as the shaft that couples a motor to an electric submersible pump. The step-down transformer may be configured as a modular unit that can be inserted between components (e.g. motor and seal) that are manufactured using conventional designs.

Claims

1. A method for providing power to downhole equipment, the method comprising:

providing power at a surface location;

transforming the power at the first voltage to a second voltage which is greater than the first voltage;

applying the power at the second voltage to a power cable, thereby transmitting the power over the power cable from the surface location to a downhole location, wherein the power is received at the downhole location at a third voltage, wherein the third voltage is less than the second voltage and greater than the first voltage;

transforming the power received at the downhole location from the third voltage to a fourth voltage which is less than the third voltage; and

providing the power at the fourth voltage to the downhole equipment.

2. The method of claim 1, wherein the first and fourth voltages are less than 8 kV and the second and third voltages are greater than 8 kV.

3. The method of claim 1, wherein the second voltage is at least twice the first voltage.

4. The method of claim 1, wherein the downhole equipment comprises an electric submersible pump (ESP) system.

5. The method of claim 4, further comprising providing one or more toroidal transformers at the ESP system, wherein the toroidal transformers transform the power received at the downhole location from the third voltage to the fourth voltage.

6. A system comprising:

an electric submersible pump apparatus having

a pump,

an electric motor,

a shaft coupled between the motor and the pump, wherein the motor is configured to rotate the shaft and thereby drive the pump, and

a step-down transformer subsystem coupled to the motor, wherein the transformer subsystem is configured to receive power from a power cable at a first voltage, to transform the power to a second voltage which is less than the first voltage, and to provide the power at the second voltage to the motor.

7. The system of claim 6, wherein the transformer subsystem comprises one or more toroidal transformers, each toroidal transformer having an axial aperture therethrough, and each being positioned with the shaft extending through the axial aperture.

8. The system of claim 7, further comprising a seal, wherein the seal is coupled to the pump, and wherein the transformer subsystem is coupled between the motor and the seal.

9. The system of claim 8, wherein the transformer subsystem is configured to enable oil to flow therethrough between the motor and the seal.

10. The system of claim 7, wherein the power comprises three-phase power, wherein the transformer subsystem comprises three sets of the toroidal transformers, and where each of the three sets of the toroidal transformers is configured to transform a unique one of the phases of the three-phase power.

11. The system of claim 6, wherein each of the toroidal transformers includes a toroidal core formed from a material having a Curie temperature of at least 500°

F.

12. The system of claim 6, wherein the step-down transformer comprises a self-contained, modular unit.

13. The system of claim 6, further comprising:

surface equipment configured to produce power at a surface voltage; and

a power cable coupled to the surface equipment and configured to transmit the power produced by the surface equipment to the transformer subsystem.

14. The system of claim 13, wherein the surface equipment includes:

a drive unit configured to produce output power at a preliminary voltage; and

a step-up transformer configured to transform the output power at the preliminary voltage to the surface voltage.

15. A method for retrofitting an electric submersible pump (ESP) system comprising:

providing an ESP system, wherein the ESP system includes a drive subsystem configured to generate output power at a first voltage, and a motor which is coupled to the drive subsystem by a power cable, wherein the motor is configured to receive power from the cable at a second voltage and to operate using the received power at the second voltage;

inserting a step-up transformer between the drive subsystem and the power cable, wherein the step-up transformer transforms the output power to a third voltage which is greater than the first voltage and provides the output power at the third voltage to the power cable; and

inserting a step-down transformer between the power cable and the motor, wherein the step-down transformer receives power received from the power cable at a fourth voltage which is greater than the second voltage, transforms the power at the fourth voltage to the second voltage, and provides the power at the second voltage to the motor.

16. The method of claim 15, wherein the first and second voltages are less than 8 kV and the third and fourth voltages are greater than 8 kV.

17. The method of claim 15, wherein the third voltage is at least twice the first voltage and the fourth voltage is at least twice the second voltage.

18. The method of claim 15, wherein the step-down transformer comprises a self-contained, modular unit that is coupled to the motor without modification of the motor.

19. The method of claim 15, wherein the transformer subsystem comprises one or more toroidal transformers, each toroidal transformer having an axial aperture therethrough, and each being positioned with a shaft of the motor extending through the axial aperture.