past the annular seal.

The instrument sub may have a housing having a bolt pattern on at least one end for bolting to the pump. A shaft is mounted within the housing with radial bearings for coupling to a shaft assembly extending from the  motor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1is a schematic side view of a well pump assembly in accordance with this disclosure.

FIG. 2 is a sectional view of one of the instrument subs of the pump assembly of FIG. 1, taken along the line 2-2 of FIG. 1 and with the instrument pump  stages not  shown.

FIG. 3 is a sectional view similar to FIG. 2, but showing an alternate embodiment of a housing for the instrument sub.

FIG. 4 is a partially schematic axial sectional view of the instrument  sub shown in FIGS. 1 and 2.

FIG. 5 is a partially schematic enlarged axial sectional view of a portion of the instrument  sub shown in FIG.   4.

DETAILED  DESCRIPTION   OF THE

DISCLOSURE

Referring to FIG. 1, a cased well 11 has a conventional production tree 13 at its upper end. A string of tubing 15 is suspended by tree 13 and extends into the well. Tubing 15 may be sections of tubing secured together with threaded ends, or if may comprise continuous coiled tubing. Tubing 15 supports an electrical submersible pump assembly (ESP) 17.

ESP 17 includes a motor 19, illustrated at its lower end. Motor 19 is normally a three-phase electrical motor, but it could be a DC motor or a hydraulic or gas powered motor. A seal section 21 is secured to the upper end of motor 19. Seal section 21 is a conventional device that has means within, such as a bladder or bellows, for reducing pressure differential between the lubricant in motor 19 and well fluid in well 11. Seal section 21 could be formed as a part of motor 19, and may include a thrust  bearing.

In this embodiment, a lower instrument sub 23 is coupled above an intake member 25, which in turn, is coupled to the upper end of seal section 21. The upper end of lower instrument sub 23 connects to a primary pump 27. Lower instrument sub 23 has at least one pump stage, thus could be considered to be a secondary pump. Primary pump 27 has a

sub; several hundred pump stages 29 could be employed in primary pump 27. Primary pump 27 could comprise tandem pumps connected together. Primary pump 27 is preferably a centrifugal pump, with each pump stage 29 comprising an impeller and a dillliser.

Primary pump 27 includes a discharge adapter 31 on its upper end. In this example, an upper instrument sub 33, which may be identical to lower instrument sub 23, connects to discharge adapter 31. The upper end of upper instrument sub 33 connects to tubing  15.

A motor lead 35 has a connector 37 on its lower end that connects to the upper end of motor 19. Motor lead 35 has an upper end that connects via a connector or splice 41 to power cable 39. Splice 41 is normally located above ESP 17. Power cable 39 extends alongside tubing 15 to production tree 13, and from production tree 13 to a controller 42 adjacent production tree 13. Clamps or straps (not shown) connect power cable 39 to tubing 15 at various distances to transfer the weight of power cable 39 to tubing 15. Controller 42 supplies power down power down power cable 39 and motor lead 35 to motor 19. If the power is hydraulic or gas, it will be supplied down a power conduit to motor 19. Controller 42 may also have a variable speed drive system for varying the frequency of the power supplied and thus the rotational speed of motor 19. In addition, controller 42 has circuitry for receiving sensed information from instrument subs 23, 33 concerning operating parameters of ESP 17. That informa- tion may be displayed and/or transmitted to remote loca- tions.

In this example, a sensor line 43 connects lower instru- ment sub 23 to controller 42 to communicate information sensed. Similarly, a sensor line 45 connects upper instrument sub 33 to controller 42. Sensor lines 43, 45 may comprise separate instrument wires from motor lead 35 and power cable 39 and extend continuously along with power cable 39 to controller 42. Sensor lines 43, 45 may join each other at or below splice 41 and comprise a single sensor line extend-