Apparatus and system for sealing submersible pump assemblies

1. A seal section for an electric submersible pump assembly comprising:

a rotatable shaft extending axially through a seal section;

a head tubularly encasing a top portion of the seal section and threadedly coupled to a centrifugal pump intake;

wherein the head further comprises:

at least one well-fluid entrance aperture proximate to a hydrodynamic bearing set, the entrance aperture extending radially through a wall of the head; and

at least one well-fluid exit aperture proximate to a mechanical seal and extending radially through the wall of the head;

a stationary sand barrier downstream of the mechanical seal, the sand barrier sealedly coupled to the rotatable shaft on an inner diameter and the head on an outer diameter;

the hydrodynamic bearing set located in the top portion of the seal section between the sand barrier and the mechanical seal, the hydrodynamic bearing set comprising a thrust bearing fixedly attached to the head and a thrust runner keyed to the rotatable shaft; and

a motor-oil vent port located upstream of the mechanical seal and extending radially through the wall of the head from a communication port.

2. The seal section of claim 1 , wherein the thrust bearing and thrust runner each comprise a plurality of diamond-coated pads circumferentially disposed about a locking plate.

3. The seal section of claim 1 , wherein the sand barrier further comprises an o-ring on an outer diameter of the sand barrier and a lip seal on an inner diameter of the sand barrier.

4. The seal section of claim 1 , further comprising an adapter pressed against the head, the adapter configured to secure the sand barrier in place.

5. The seal section of claim 1 , further comprising a tungsten carbide bushing set keyed to the shaft upstream of the mechanical seal.

6. The seal section of claim 1 , wherein the entrance and exit apertures are disposed circumferentially about the head.

7. The seal section of claim 1 , wherein a space between the thrust bearing and thrust runner is between about 0.00001 and 0.005 inches thick.

8. A electric submersible pump (ESP) system for pumping solid-laden fluid comprising:

a thrust chamber of an ESP seal section, the thrust chamber sealed from well fluid on a downstream side by a stationary sand barrier and on an upstream side by a mechanical seal, the thrust chamber further comprising:

a rotatable shaft extending axially through the chamber;

a head tubularly encasing the thrust chamber, the head threadedly coupled to a centrifugal pump intake; and

a diamond-coated hydrodynamic bearing set inside the thrust chamber;

wherein well fluid enters and exits the thrust chamber through cross-drilled apertures in the head, and wherein the well fluid forms a hydrodynamic film between the bearing set.

9. The system of claim 8 , further comprising a check valve located upstream of the thrust chamber and extending radially through a wall of the head, the check valve fluidly coupled to a communication port and configured to vent expanding motor oil.

10. The system of claim 8 , wherein the bearing set comprises a pad, the pad comprising leached diamond.

11. The system of claim 8 , wherein the bearing set comprises a bearing pad, the bearing pad further comprising a facing table of polycrystalline diamond integrally bonded to a substrate.

12. An apparatus for absorbing a thrust of an electric submersible pump (ESP) comprising:

an ESP configured to pump a well fluid;

an electric motor operatively coupled to the ESP, the motor operating to rotate a shaft of the ESP; and

a seal section located between the ESP and the motor, the seal section comprising:

a stationary thrust bearing comprising a first plurality of diamond coated pads arranged circumferentially about a thrust bearing locking plate;

a thrust runner paired with the stationary thrust bearing to form a hydrodynamic bearing set, the thrust runner configured to rotate with the shaft and, comprising a second plurality of diamond coated pads arranged circumferentially about a thrust runner locking plate;

wherein the well fluid forms a hydrodynamic film between the first plurality of diamond coated pads and the second plurality of diamond coated pads during operation of the motor; and

wherein the hydrodynamic bearing set is located between a stationary sand barrier and a mechanical seal of the seal section.

13. The apparatus of claim 12 , wherein the hydrodynamic bearing set is located in a thrust chamber in a head of the seal section.