Isolated pressure compensating electric motor connection and related methods

• US 8,905,727 B2
• Filed: 07/19/2012
• Issued: 12/09/2014
• Est. Priority Date: 08/11/2011
• Status: Active Grant

• Current Assignee: Baker Hughes Holdings LLC (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Frey, Jeffrey G., Semple, Ryan P.
• Primary Examiner(s): Kramer, Devon
• Assistant Examiner(s): BRUNJES, CHRISTOPHER J
• Application Number:
  US13/553,176
• Publication Number:
  US 20130040480A1
• Time in Patent Office: 873 Days
• Field of Search: 417/414, 417/423.3, 417/424.1, 417/424.2, 417/439, 310/71, 310/87, 439/289, 439/700, 439/824
• US Class Current: 417/414
• CPC Class Codes: E21B 43/128 Adaptation of pump systems with down-hole electric drives
• CPC Class Codes: F04B 47/06 having motor-pump units situated at great depth

Abstract

Isolated pressure compensating electrical motor connections and related methods are provided. According to an example of a sealed motor electrical connection, the connection incorporates a sealed female motor connection positioned to receive a male motor connector. The female motor connector has one or more independent dielectric oil chambers each pressure compensated by a bellow or similar device interfaced with the motorhead oil and/or well annulus fluid to thereby pressure compensate the chamber pressure of the female motor connection with that of the internal motor and/or well annulus. This configuration locates the electrical connection point of the motor lead extension with the motor lead wires to a separate area outside the motor to thereby prevent the occurrence of phase to phase or phase to ground shorts occurring in this critical area due to conductive element contamination that may reside in the motor oil or the well bore fluids.

Claims

1. A submersible well pump assembly, comprising:

a pump;

an electrical motor cooperatively connected with the pump for driving the pump, the motor having a motor housing that is filled with a dielectric motor lubricant, the motor having an internal motor lead immersed in the motor lubricant;

a seal/equalizer section mounted to the motor, the seal/equalizer section being in fluid pressure communication with the motor lubricant and with well fluid surrounding the motor for reducing a pressure difference between the motor lubricant and the well fluid surrounding the motor;

a female motor connector comprising a connector housing containing at least one chamber, the female motor connector being connected to an outer surface portion of the motor housing, the chamber being filled with a female motor connector dielectric fluid;

wherein said at least one chamber comprises an inner chamber and an outer chamber containing the inner chamber;

the female motor connector dielectric fluid comprises an inner dielectric fluid in the inner chamber and an outer dielectric fluid in the outer chamber;

the inner dielectric fluid is sealed from the outer dielectric fluid;

at least one female pressure compensation device mounted to the female motor connector and in fluid pressure communication with the at least one chamber for reducing a pressure difference between the female motor connector dielectric fluid and the well fluid surrounding the motor;

the internal motor lead extending from within the motor housing into the at least one chamber and having an electrical contact on an end within the at least one chamber;

a power cable having at least one conductor to supply electrical power to the motor;

a male motor lead connector on an end of the power cable, the male motor lead connector being releasably secured to the female motor connector;

at least one of the conductors of the power cable extending into the female motor connector housing and electrically mating with the electrical contact of the internal motor lead when the male motor lead connector is secured to the female motor connector; and

a seal around the internal motor lead that seals the motor lubricant from the dielectric fluid in the at least one chamber.

2. The assembly according to claim 1, further comprising:

a conduit extending from the pressure compensation device to an interior of the motor for communicating pressure of the motor lubricant to the pressure compensation device; and

wherein

the conduit bypasses the seal.

3. The assembly according to claim 1, wherein:

said at least one pressure compensation device comprises;

a inner pressure compensation device in fluid communication with the dielectric fluid in the inner chamber; and

a outer pressure compensation device in fluid communication with the dielectric fluid in the outer chamber.

4. The assembly according to claim 1, wherein said at least one pressure compensation device comprises:

a inner pressure compensation device in fluid communication with the dielectric fluid in the inner chamber;

a outer pressure compensation device in fluid communication with the dielectric fluid in the outer chamber; and

at least one conduit extending through the motor housing, bypassing the seal, and to the inner and the outer compensation devices, the conduit communicating motor lubricant from within the motor to the inner and outer compensation devices.

5. The assembly according to claim 1, further comprising:

a spring biased shuttle pin having an end located within the chamber prior to and following the connection of the male motor lead connector with the female motor connector, the shuttle pin electrically engaging the electrical contact on the internal motor lead with the conductor when the male motor lead connector is connected to the female motor connector housing.

6. The assembly according to claim 1, further comprising:

a shuttle pin positioned within the chamber and slidably mounted to the female motor connector between an engaged position having an inner end engaging the electrical contact of the internal motor lead, and a disengaged position with the inner end disengaged from the electrical contact of the internal motor lead, the inner end of the shuttle pin being located in the chamber before and after connection of the male motor lead connector to the female motor connector;

a spring urging the shuttle pin to the disengaged position; and

wherein

the conductor of the power cable engages and moves the shuttle pin to the engaged position in response to connecting the male motor lead connector to the female motor connector.

7. The assembly according to claim 6, further comprising:

a seal extending around the shuttle pin that seals the shuttle pin to the female motor connector and blocks entry of well fluid into the chamber.

8. An electrical submersible pump assembly, comprising:

a pump;

an electrical motor for driving the pump, the motor having a motor housing that is filled with a dielectric motor lubricant, the motor having an internal motor lead immersed in the motor lubricant;

a seal/equalizer section mounted to the motor, the seal/equalizer section being in fluid pressure communication with the motor lubricant and with well fluid surrounding the motor for reducing a pressure difference between the motor lubricant and the well fluid surrounding the motor;

a female motor connector comprising a housing containing an inner chamber located within an outer chamber, each of the chambers being filled with a female motor connector dielectric fluid, the female motor connector dielectric fluid in the inner chamber being isolated from the female motor connector dielectric fluid in the outer chamber and from the motor lubricant, the female motor connector being connected to an outer surface portion of the motor housing;

the motor lead extending sealingly through an aperture in the motor housing, sealingly through a portion of the outer chamber, and sealingly into the inner chamber, the motor lead terminating in an electrical contact within the inner chamber;

at least one pressure compensation device mounted to the female motor connector in fluid pressure communication with the female motor connector dielectric fluid contained in the inner and outer chambers, for reducing a pressure differential between the dielectric fluid contained in the inner and outer chambers and the well fluid surrounding the motor;

a power cable having at least one conductor to supply electrical power to the motor;

a male motor lead connector on an end of the power cable, the male motor lead connector being releasably secured to the female motor connector; and

at least one of the conductors of the power cable extending from the male motor lead connector into the female motor connector housing and into electrical engagement with the electrical contact on the end of the motor lead within the inner chamber when the male motor lead connector is secured to the female motor connector, the conductor being in electrical disengagement with the electrical contact on the end of the motor lead when the male motor lead connector is disengaged from the female motor connector.

9. The assembly according to claim 8, further comprising:

a conduit extending from the pressure compensation device to an interior of the motor for communicating pressure of the motor lubricant to the pressure compensation device.

10. The assembly according to claim 8, wherein:

said at least one pressure compensation device comprises;

a inner pressure compensation device in fluid communication with the dielectric fluid in the inner chamber; and

a outer pressure compensation device in fluid communication with the dielectric fluid in the outer chamber.

11. The assembly according to claim 8, wherein said at least one pressure compensation device comprises:

a inner pressure compensation device in fluid communication with the dielectric fluid in the inner chamber;

a outer pressure compensation device in fluid communication with the dielectric fluid in the outer chamber; and

at least one conduit extending through the motor housing to the inner and the outer compensation devices, the conduit communicating motor lubricant from within the motor to the inner and outer compensation devices.

12. The assembly according to claim 8, wherein said at least one pressure compensation device comprises:

a inner pressure compensation device in fluid communication with the dielectric fluid in the inner chamber;

a outer pressure compensation device in fluid communication with the dielectric fluid in the outer chamber; and

at least one well conduit communicating well fluid to the inner and the outer compensation devices.

13. The assembly according to claim 8, further comprising:

a spring biased shuttle pin having an inner end with an electrical contact in the inner chamber prior to and following connection of the male motor lead connector with the female motor connector, the inner end of the shuttle pin contacting the electrical contact of the internal motor lead while the male motor lead connector is connected to the female motor connector housing.

14. The assembly according to claim 8, further comprising:

a shuttle pin sealingly and slidably positioned within a shuttle pin passage in the female motor connector, the shuttle pin having an inner end within the inner chamber and an outer end recessed within the shuttle pin passage;

the shuttle pin having an engaged position with the inner end of the shuttle pin engaging the electrical contact of the internal motor lead;

the shuttle pin having a disengaged position with the inner end disengaged from the electrical contact of the internal motor lead;

a spring urging the shuttle pin to the disengaged position; and

wherein the conductor of the male motor lead connector engages the outer end of the shuttle pin to move the shuttle pin to the engaged position when the male motor lead connector is connected to the female motor connector.

15. The assembly according to claim 14, wherein the shuttle pin also extends sealingly through a portion of the outer chamber.

16. A method of connecting a power cable to a submersible well pump assembly comprising a pump, an electrical motor for driving the pump, the motor having a motor housing that is filled with a dielectric motor lubricant, the motor having an internal motor lead immersed in the motor lubricant, and a seal/equalizer section mounted to the motor, the method comprising:

providing a female motor connector comprising a connector housing containing at least one chamber, filling the chamber with a female motor connector dielectric fluid, and connecting the female motor connector to an outer surface portion of the motor housing;

providing the connector housing with at least one chamber comprises providing an outer chamber and an inner chamber located within the outer chamber;

filling the chamber with a female motor connector dielectric fluid comprises filling each of the chambers with a dielectric fluid and isolating the dielectric fluid of the inner chamber from the dielectric fluid in the outer chamber;

providing the female motor connector with at least one pressure compensation device and placing the pressure compensation device in fluid pressure communication with the dielectric fluid in the chamber;

providing the internal motor lead with an electrical contact on an end, extending the internal motor lead from within the motor housing into the chamber, positioning the electrical contact in the chamber, and sealing the motor lead to the motor housing to isolate the motor lubricant in the motor housing from the dielectric fluid in the chambers;

providing a power cable having at least one conductor and a male motor lead connector on an end of the power cable, and releasably securing the male motor lead connector to the female motor connector;

in response to securing the male motor lead connector to the female motor connector, electrically engaging one of the conductors of the power cable with the electrical contact of the internal motor lead within the chamber;

then

lowering the assembly into the well, communicating well fluid pressure to the seal/equalizer section, and reducing a pressure difference between the motor lubricant and the well fluid surrounding the motor; and

communicating well fluid pressure to the pressure compensation device and reducing a pressure difference between the dielectric fluid in the chamber and the well fluid surrounding the motor.

17. The method according to claim 16, wherein:

providing the female motor connector with at least one pressure compensation device comprises providing an inner pressure compensator for the inner chamber and an outer pressure compensator for the outer pressure compensator.

18. The method according to claim 16, wherein:

extending the internal motor lead from within the motor housing into the chamber comprises extending the internal motor lead sealingly through a portion of the outer chamber and sealingly into the inner chamber.

19. The method according to claim 16, wherein:

communicating well fluid pressure to the pressure compensation device comprises communicating motor lubricant from the motor housing to the pressure compensation device.

20. The method according to claim 16, wherein:

providing a female motor connector further comprises mounting a shuttle pin within the female motor connector, the shuttle pin having an inner end within the inner chamber and an outer end sealed from the inner and outer chambers; and

in response to securing the male motor lead connector to the female motor connector, engaging the outer end of the shuttle pin with the conductor and moving the shuttle pin inward, electrically engaging the inner end of the shuttle pin with the electrical contact on the internal motor lead.