Patent Application
20090041597
This invention relates in general to electrical submersible well pumps, and in particular to connections between the seal section of the pump assembly and the pump.
Electrical submersible well pumps are commonly used for hydrocarbon well production. A typical pump assembly has an electrical motor with a seal section or protector on its upper end. The motor is filled with a dielectric lubricant. The seal section has an equalizer in communication with that lubricant. The equalizer is also in fluid communication with the well bore fluid for equalizing the pressure of the lubricant to that of the well bore fluid. Typically the seal section will also have a thrust bearing for absorbing downward thrust from the pump.
The pumping assembly may comprise one or more pumps and optionally a gas separator. The pumps are rotary pumps driven by a shaft of the motor. They may be either progressing cavity pumps or they may be centrifugal pumps having a large number of stages, each stage having an impeller and a diffuser. If a gas separator is employed, typically it has a rotary gas separating component for separating gas from the well fluid prior to the well fluid entering the pump.
A different connector is required on the lower end of the pump depending upon whether the pump is to connect directly to a seal section or to another component of the pumping assembly, such as a gas separator or another pump. The connectors are not readily interchangeable between pumps, thus the manufacturer may be required to keep both types. The reason for having both types of pumps has to do with whether the connector has intake ports or not. If the pump is connecting to an upstream component such as another pump or a gas separator, its connector would not have intake ports in it. If connecting directly to the seal section, the connector would need intake ports.
As further explanation of the prior art and referring to
If the manufacturer wishes to use pump 31 without connecting it to an upstream component, such as another pump or gas separator, he can do so by connecting it to a separate intake housing 47. Intake housing 47 is a separate sub that has intake ports 49 for well fluid to pass inward and up to pump 31. Intake housing 47 has its own short shaft 51 mounted therein and which connects to pump shaft 53 by a coupling 55. A radial bearing 57 supports intale shaft 51 in housing 47. Radial bearing 57 does not form a seal. A coupling on the lower end of intake housing shaft 51 will connect it to a seal section shaft (not shown). Intake housing 47 has a radial flange 61 for bolting to the seal section (not shown). While combining pump 31 with intake housing 47 allows a manufacturer to use pump 31 either as a tandem pump or as a single pump without a gas separator, it requires extra expense because of intake housing 47.
Pump 63 is operable only by connecting it directly to the seal section. It cannot be used as a tandem pump because of its intake ports 71. In addition, connectors 67 and 37 (
In this invention, the seal section between the motor and the pumping assembly has a head on its end with an intake. The intake draws well bore fluid into the pump. The pump assembly, whether it includes is a gas separator, multiple pumps, or a single pump, has a simple connector on its lower end without intake ports. Placing the intake in the head of the seal section allows a standard connector to be utilized on all of the pumps regardless of whether the pump is to be connected directly to the seal section or to an upstream component of the pumping assembly.
Referring to
Seal section 17 has a head 19 on its upper end. Head 19 forms a part of seal section 17 and has intake ports 21 for drawing well fluid into head 19. ESP 11 may include an optional gas separator 23, which connects to the upper end of seal section head 19. Gas separator 23 separates gas from the well fluid flowing into intake 21 and discharges the gas out the gas outlet 25. The liquid components flow upward to a pump 27 that connects to the upper end of gas separator 23. Pump 27 may be a centrifugal pump or another type of rotary pump, such as a progressing cavity pump. Pump 27 is suspended by a string of tubing 29 through which the pump discharges. Gas separator 23 is employed only if conditions merit; in many instances pump 27 would connect directly to seal section head 19. Another pump could optionally be connected to the upper end of pump 27 in a tandem arrangement.
Referring to
Seal section head 19 has a flange 87 on its upper end that has a bolt pattern 89 that mates with bolt pattern 85. Connector 79 thus attaches directly to seal section head 19, if desired. A lower portion of connector 79 inserts into seal section head 19 and is sealed to seal section head 19 by a seal 90. Seal section 17 has a cylindrical housing 91 with internal threads 93 at its upper end. Seal section head 19 has external threads 95 on a lower interior portion that extend into housing 91. Threads 95 mate with threads 93 to secure head 19 to seal section housing 91. A seal 97 seals head 19 to the interior of seal section housing 91.
Seal section head 19 has an axial passage 99 extending through it. Seal section 17 has a shaft 101 that extends through it. Shaft 101 extends upward through axial passage 99. A bushing 103 in passage 99 radially stabilizes shaft 101, but does not seal. A seal assembly 105 is located above bushing 103 for sealing shaft 101 to passage 99. Seal assembly 105 may be a variety of types and combinations of seals. In this type, it includes a rotating member that rotates with shaft 101 and is urged by a spring against a stationary member. Seal assembly 105 seals a cavity 107 in head 19 from a cavity 109 in the interior of seal section 17. Seal head cavity 107 is in fluid communication with well bore fluid because of intake ports 21. Cavity 109 is in fluid communication with lubricant of motor 15 (
Pump 27 has a pump shaft 111 that extends downward a short distance below connector 79. A coupling 113 connects pump shaft 111 to seal section shaft 101. Coupling 113 is located within seal head cavity 107.
Seal section 17 (
Equalizer bag 115 has well fluid on its exterior so that it will equalize or at least greatly reduce any pressure difference between the motor lubricant and the well bore fluid. In this embodiment, a port 121 extends downward from the exterior of head 19 to the interior of seal section housing 91 to deliver well fluid to the exterior of bag 115, as illustrated by the dotted lines in
In the operation of ESP 11, in one mode, pump 27 is connected directly to seal section head 19. When motor 15 is energized, well fluid will be drawn through intake ports 21 for being acted on by pump 27. Seal section 17 protects the lubricant in the motor from contamination by the well bore fluid. Seal section 17 also equalizes the pressure of the lubricant to that of the well bore fluid.
In another mode, as shown in
The invention has significant advantages. By placing the intake in the head of the seal section, connectors for the pumping assemblies may be standardized. The same pump could be used as a single, stand-alone pump, or one connected to a gas separator, or one connected to a lower tandem pump.
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.
