Electrical submersible pump discharge head

A discharge head for an electrical submersible pump allows the pump assembly to be supported on coiled tubing. The discharge head has a cable passage through which the power cable passes. A motor lead extends from the motor alongside the pump and to the discharge head. The discharge head has flow passages that are offset relative to the longitudinal axis of the discharge head. An annulus seal mounted to the discharge head seals the annulus surrounding the discharge head. A power cable extends through the coiled tubing in one embodiment and is strapped to the coiled tubing in another embodiment.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates in general to electrical submersible pumps for 
wells, and in particular to a discharge head for use with an electrical 
submersible pump suspended on coiled tubing within the well. 
2. Description of the Prior Art 
A conventional electrical submersible pump installation for oil wells 
supports the downhole pump assembly on production tubing. The production 
tubing is made up of sections of metal pipe secured together by threaded 
couplings. The submersible pump assembly includes at least one electrical 
motor, and at least one centrifugal pump. The pump normally locates above 
the motor and has a discharge head that secures to the production tubing. 
The production tubing supports the weight of the pump assembly as it is 
lowered into the well. The well fluid drawn into the intake of the 
submersible pump will be pumped through the tubing to the surface. 
The electrical submersible pump must be maintained from time to time. This 
requires a workover rig which can pull the sections of tubing from the 
well to retrieve the pump, then lower a repaired or replaced pump back 
into the well. This is time consuming and expensive. 
One proposal has been to support the pump on the power cable that extends 
to the electrical motor. This would eliminate the need for tubing and the 
need for a workover rig to pull the tubing for pump maintenance. 
Conventional power cable, however, does not have sufficient strength to 
support the weight of the pump assembly in the well. Consequently, a 
special cable must be utilized that has sufficient strength to support the 
weight of the pump in the well. While some of these units have been 
installed, the expense of the cable has been too high to make this type of 
assembly common. 
It has also been proposed to support an electrical submersible pump on 
coiled tubing. Coiled tubing is a continuous metal pipe of smaller 
diameter than typical production tubing. Coiled tubing will coil onto a 
large reel and can be unrolled into the well. The coiled tubing would have 
the strength to support the pump assembly in the well. While it requires a 
unit to uncoil and coil the tubing, the pulling and running back in 
procedure should be less time consuming than the process of pulling 
conventional production tubing from the well with a workover rig. Also, 
coiled tubing would allow the pump to be installed in a live well through 
a stripper. While the concept of a coiled tubing suspended pump is 
feasible, this assembly is not commercially available at this time. 
SUMMARY OF THE INVENTION 
A discharge head for a coiled tubing supported electrical submersible pump 
assembly includes a body. The body has a neck on its upper end which 
secures to a coupling of the coiled tubing. A cable passage extends 
downward through the body and terminates at a lower end that is laterally 
offset relative to the longitudinal axis of the body. The cable extends 
through this cable passage and couples to a motor lead extending alongside 
the pump down to the motor. 
A flow passage also extends through the body, however it is completely 
separate from the cable passage. The flow passage has a lower end that is 
located on the longitudinal axis. The lower end of the body connects to 
the pump. The upper end of the flow passage is offset from the 
longitudinal axis and terminates in an outlet for discharging well fluid 
into the casing surrounding the coiled tubing. In the preferred 
embodiment, the upper portion comprises a plurality of passages, each 
spaced circumferetially from each other. 
In the preferred embodiment, an annulus seal surrounds the discharge head 
and seals to the casing. The annulus seal serves as a packer for isolating 
the casing above the discharge head from the pump intake below. The 
annulus seal secures to the discharge head and is run in with the pump 
assembly. 
In one embodiment, the power cable extends through the coiled tubing. The 
cable passage extends through the neck. In another embodiment, the power 
cable is strapped to the exterior of the coiled tubing. The upper end of 
the cable passage extends to a shoulder at the base of the neck.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to Figure the well has casing 11 installed. Casing 11 may also be 
a liner installed within larger diameter casing, with the term "casing" as 
used herein referring both to a liner and to casing. The electrical 
submersible pump assembly will be suspended within the casing 11. The 
electrical submersible pump assembly includes a motor 13, which is an 
alternating current motor. Motor 13 drives a shaft that extends through a 
seal section (not shown) for driving a centrifugal pump 15. Pump 15 is 
conventional and comprises a large number of stages of impellers and 
diffusers. 
A discharge head 17 mounts to the upper end of pump 15. Seal means, 
comprising an annular seal 18 in the embodiment shown, is carried by 
discharge head 17 for sealing discharge head 17 to casing 11. As shown in 
FIG. 2, seal 18 may be a generally cup shaped flexible elastomeric seal 18 
which slides down casing 11 as the pump assembly is lowered into the well. 
Seal 18 prevents well fluid from flowing downward past seal 18 when pump 
15 is operating. Seal 18 may be secured to discharge head 17 by various 
means. 
Discharge head 17 secures to coiled tubing 19 which extends to the surface 
and supports the weight of the electrical submersible pump assembly. 
Coiled tubing 19 is metal tubing that is continuous and shipped and stored 
on a large reel (not shown) at the surface. A three-phase electrical power 
cable 21 extends through coiled tubing 19. Power cable 21 extends through 
discharge head 17 and has a lower end which connects to a conventional 
motor lead 23. Motor lead 23 extends alongside pump 15 and into electrical 
engagement with motor 13. 
Referring to FIG. 2, discharge head 17 is supported on coiled tubing 19 by 
a coupling 25 located on the lower end of coiled tubing 19. Coupling 25 
secures to a neck 27 of discharge head 17, the neck 27 having external 
threads 29 (FIG. 4). 
Discharge head 17 has a tubular body 31 that extends downward from neck 27. 
Body 31 and neck 27 comprise a single integral member. Body 31 is a metal 
member, having an upward facing conical shoulder 33 located at the base of 
neck 27. Neck 27 has a lesser outer diameter than the outer diameter of 
body 31, defining the shoulder 33. Body 31 has a cylindrical exterior 
below shoulder 33. Seal 18 secures to the cylindrical exterior of body 31. 
At the lower end of body 31, a flange 35 serves as means for securing 
discharge head 17 to the upper end of pump 15. Threaded fasteners 39 
extend through holes 37 (FIG. 4) in flange 35 and into threaded 
receptacles in pump 15. 
Referring to FIG. 4, body 31 has a longitudinal axis 41 that coincides with 
the longitudinal axis extending through motor 13 and pump 15 (FIG. 1). A 
cable passage 43 extends through body 31. Cable passage 43 has an upper 
portion 43a that is cylindrical and coaxial with longitudinal axis 41. An 
intermediate portion 43b joins upper portion 43a. Intermediate portion 43b 
begins an angled portion which terminates at a lower portion 43c, located 
on a downward and outward facing shoulder 47. Shoulder 47 is located in a 
notch or recess 49 formed in the lower portion of body 31. Lower passage 
portion 43c has an axis that is laterally offset from longitudinal axis 
41. Also, it inclines at an angle 45 that is approximately 15 degrees 
relative to longitudinal axis 41 in the embodiment shown. As shown in 
FIGS. 5-8, intermediate portion 43b is elongated initially, resulting in 
an oblong cross section. This oblong cross section becomes less pronounced 
in FIGS. 6 and 7, and in FIG. 8 it is substantially circular. The cross 
section in the lower portion 43c is circular. The power cable 21 will 
extend through cable passage 43 and terminates in lower portion 43c for 
connecting to motor lead 23. Shoulder 47 is spaced a considerable distance 
above the flange 35. 
A plurality of upper flow passages 51a, b, c have outlets at upper shoulder 
33 of body 31. Upper flow passages 51a, b, c, shown in FIG. 5, are 
generally arcuate in cross section. Also, they are circumferentially 
spaced apart from each other. Upper flow passages 51a, b, c surround three 
sides of cable passage 43. 
Upper flow passages 51a, b, c incline and converge downward relative to 
each other and join an intermediate flow passage 53 at a common junction 
as illustrated in FIG. 7. Intermediate flow passage 53 extends downward at 
an angle 55 relative to longitudinal axis 41. Angle 55 is also 
approximately 15 degrees in the embodiment shown. Intermediate flow 
passage 53 terminates in a lower flow passage 57 at the lower end. Lower 
flow passage 57 is circular in cross section. Preferably the 
cross-sectional area of the lower flow passage 57 is approximately the 
same as the cross-sectional area of intermediate flow passage 53. Also, 
preferably the sum of the cross-sectional areas of the upper flow passages 
51a, b, c is approximately equal to the cross-sectional area of the 
intermediate flow passage 53. Consequently, the flow area remains 
generally constant throughout the discharge head 17. 
In the embodiment shown in FIGS. 1-8, the power cable 21 extends downward 
and terminates in an electrical connector 59. Electrical connector 59 fits 
sealingly in passage lower portion 43c. Electrical connector 59 has three 
pins 61, each of which is soldered to one of the conductors of power cable 
21. Pins 61 are supported in an electrical insulator 63. A mating 
electrical connector (not shown) on the upper end of motor lead 23 (FIG. 
2) releasably connects to electrical connector 59. A seal means including 
seals 65 in the upper cable passage 43a seals power cable 21, preventing 
leakage of well fluid into the cable passage 43a, b, c. 
In operation, the operator will assemble the motor 13 to the pump 15 
through a seal section (not shown). The operator solders the conductors at 
the lower end of power cable 21 to electrical connector 59 and connects 
the upper end of motor lead 23 to electrical connector 59. The operator 
will extend motor lead 23 alongside pump 15. Annulus seal 18 will be 
mounted to discharge head 17. The operator secures coiled tubing coupling 
25 to threads 29 (FIG. 4) of discharge head 17. 
The operator then lowers the entire assembly into the well on coiled tubing 
19. The operator handles this by utilizing a conventional coiled tubing 
deployment (not shown) at the surface. The annulus seal 18 slides downward 
through casing 11 until the assembly reaches the desired depth. 
To produce well fluid, the operator supplies electrical power to power 
cable 21. The power energizes motor 13, which will drive the pump 15. 
Fluid will be produced out pump 15 upward through the flow passages 57, 
53, and 51a, b, and c. The fluid flows up casing 11 in the annulus 
surrounding coiled tubing 19. Annulus seal 18 isolates the intake of pump 
15, which is at the lower end of pump 15. 
FIGS. 9 and 10 illustrate an alternate embodiment of discharge head 17'. In 
this embodiment, the power cable 21' is strapped to the exterior of the 
coiled tubing 19', rather than extending through the coiled tubing. The 
cable passage 43' has an upper end at shoulder 33' rather than in neck 
27'. A plug 67 is secured in neck 27'. An upper electrical connector 69 of 
the same type as lower electrical connector 59' sealingly locates in the 
upper end of cable passage 43'. Power cable 21, has a mating electrical 
connector on its lower end that couples to upper electrical connector 69. 
A short feed through cable 71 extends within cable passage 43' between 
upper electrical connector 69 and lower electrical connector 59'. 
In the alternate embodiment, the well fluid is discharged in the same 
manner through fluid passages 51', 53', and 57' as in the first 
embodiment. The cable passage 43' provides a bypass for the cable 21' for 
the annulus seal 18'. 
The invention has significant advantages. The discharge head supports the 
electrical submersible pump assembly on the coiled tubing, and allows 
discharge into the casing. The discharge head provides an effective means 
for coupling the cable extending through the coiled tubing to the motor 
lead. The annulus seal eliminates the need for installing a packer in the 
well prior to lowering the pump assembly. The discharge head provides an 
effective means of bypassing the power cable past the annulus seal around 
the discharge head. 
While the invention has been shown in only one of its forms, it should be 
apparent to those skilled in the art that it is not so limited, but is 
susceptible to various changes without departing from the scope of the 
invention.