The present disclosure relates to downhole pumping systems submersible in well bore fluids. More specifically, the present disclosure concerns improved pump motors to drive the submersible pumping systems that can be used in bottom hole temperatures of above about 180° C. (356° F.).
Submersible pumping systems are often used in hydrocarbon producing wells for pumping fluids from within the well bore to the surface. These fluids are generally liquids and include produced liquid hydrocarbon as well as water. One type of system used in this application employs a electrical submersible pump (ESP). ESP's are typically disposed at the end of a length of production tubing and have an electrically powered motor. Often, electrical power may be supplied to the pump motor via an electrical power cable from the surface that is strapped alongside the tubing.
A motor lead is secured to the lower end of the power cable, the motor lead terminating in a connector that plugs into a receptacle of the motor. This connector is typically known as a pothead connector.
ESP motors have stators with slots. Insulated magnet wire is wound through the slots in a selected pattern. A sheet of an insulation material may be wrapped around each bundle of magnet wires within each of the slots. The magnet wires extend below a lower end of the stator in loops spaced around a longitudinal axis of the motor. An end bell insulation sheet is formed as a cylinder and extends around all of the loops. The loops are arranged in phases spaced longitudinally from the longitudinal axis. Phase-to-phase insulation sheets are rolled into cylindrical shapes and between the different phase groups. The magnet wires may be bonded in the slots with an epoxy. In one technique, magnet wire leads are spliced to upper ends of three of the magnet wires. The magnet wire leads extend from the upper end of the stator to internal contacts in the motor electrical plug-in receptacle.
Typically, the pumping unit is disposed within the well bore just above where perforations are made into a hydrocarbon producing zone. This placement thereby allows the produced fluids to flow past the outer surface of the pumping motor and provide a cooling effect.
In spite of the heat transfer between the fluid and the motor, over a period of time the motor may become overheated. Overheating may a problem when the fluid has a high viscosity, a low specific heat, and a low thermal conductivity. This is typical of highly viscous crude oils. Also, the motor may be forced to operate at an elevated temperature, past its normal operating temperature, in steam injection wells. Elevated well temperatures can reduce motor life.
In view of the foregoing, electric submersible pumping systems that are capable of operating in bottom hole temperatures of above about 180° C. (356° F.) are provided as embodiments of the present disclosure. The electric submersible pumping system includes an electric motor coupled to a pump. A power lead receptacle is mounted to a housing of the motor. A power cable having a motor lead with a pothead connector on its lower end plugs into the receptacle. The motor has a stator with a plurality of slots, each of the slots having a bundle of magnet wires.
Magnet wires are threaded within various ones of the slots for each phase of the motor. Each of the magnet wires has at least one insulation layer. Each of the magnet wires has a lead portion protruding from the stator with an upper end configured as an electrical terminal that releasably attaches to an internal electrical contact of the receptacle. Each of the magnet wires is a continuous wire without splices from within the stator to the electrical terminal.
At least one tube formed of an insulation material surrounds but is not bonded to the insulation layer on each of the motor leads. The tube has a lower end at an upper end of the stator and an upper end at the electrical terminal.
Also, the magnet wires and the conductors in the motor lead may be insulated with a high temperature electrical insulation. In one of the embodiments, an e-base polyimide film is adhered to an electrical conductor by a polyimide adhesive. In another embodiment, the E-base polyimide film is adhered to the conductor by a fluoropolymer adhesive. In a third embodiment a perfluoropolymer is extruded over the conductor. Similar insulation may be employed at a Y-point connection that connects the three magnet wires below the stator.
In one embodiment, the insulation comprises a tape of a polyimide film having inner and outer adhesive layers. The tape has a first wrap wrapped helically around each conductor in a first direction. A second wrap wraps helically around the first wrap in a second direction. The outer adhesive layer of the first wrap bonds to the inner adhesive layer of the second wrap. The outer insulation of the second wrap remains free of any bonding engagement to any other insulation materials.
A slot insulation surrounds at least a portion of each of the bundles of magnet wires in the slots. The slot insulation comprises a sheet of E-base polyimide film in one of the embodiments. The sheet of E-base polyimide film may be sandwiched between sheets of other polymers, such as polyether ether ketone (PEEK) and polytetrafluoroethylene (PTFE).
An end bell on a lower end of the stator is surrounded by loops of magnet wire protruding past the lower end of the stator. The loops of magnet wire are grouped into three phases. An end bell insulation comprising a sheet of E-base polyimide extends around all of the loops of magnet wire. Sheets of phase-to-phase insulation extend around the end bell between each of the phases, the phase-to-phase insulation also comprising sheets of E-base polyimide. The end bell insulation and phase-to-phase insulation may include sheets of other polymers, such as PTFE, that sandwich the E-base polyimide sheets between them.
The motor contains a PAO dielectric lubricant that has additives designed to dissipate amino acid. The acid is created by reactions with the epoxy in the slots of the stator.
Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:
Power cable 20 extends alongside production tubing 14, terminating in a splice or connector 21 that electrically couples cable 20 to a motor lead 23. On its lower end, motor lead 23 connects to a pothead connector 22 that electrically connects and secures motor lead 23 to motor housing 24 of electric motor 16. In another embodiment, cable 20 can extend all the way from the surface to pothead connector 22, thereby eliminating the need for motor lead 23. Also, in another embodiment, ESP could be supported on coiled tubing, rather than production tubing 14. The power cable would be located inside the coiled tubing.
ESP system 11 has many electrical wires, including those in motor lead 23 and internal wires in motor 16. At least some of the wires and other components are insulated for high temperature applications.
Referring to
In the preferred embodiment, inner and outer adhesive layers 30 and 31 differ from each other and also differ from the material forming adhesive layers 26 and 28 in
In
Power cable 20 may be conventional or it may have insulation in accordance with a selected one of the systems of
Female terminals 46 stab into engagement with mating male terminals 46 mounted within an I-block 58 formed of an electrical insulation material. I-block 58 is secured within a receptacle in motor housing 24. This arrangement could be reversed, with female connectors mounted in I-block 58. Male terminals 48 may be secured within I-block 58 as variety of ways. In this example, each male terminal 48 has a lower end that abuts a shoulder 50 within each hole 52 in I-block 58.
Each male terminal 48 is secured to a magnet wire 60 to supply power to the motor. Magnet wire 60 has an electrical conductor 62 surrounded by one or more layers of insulation 63 (
Referring to
Referring to
A slot insulation 74 extends around the periphery of each slot 70, wrapping around the bundle of magnet wires 60. Slot insulation 74 is made up of one or more layers of electrical insulation. In this embodiment, slot insulation 74 has an inner layer 76, an intermediate layer 78, and an outer layer 80. During installation, slot insulation 74 is folded into a tube and inserted through slots 70 of stator 65 before inserting magnet wires 60. Preferably slot insulation 74 does not bond to disks 68 or to magnet wires 60 but the layers 76, 78 and 80 could bond to each other. The slot insulation 74 within each slot 70 extends a full length of stator 65.
Referring again to
In one embodiment, each phase-to-phase insulation sleeve 108 is of the same material and layers as end bell insulation 100. That is, each insulation sleeve 108 comprises three layers 110, 112 and 114. Timer layer 110 and outer layer 114 comprise sheets of PTFE. Intermediate layer 112 comprises an E-base polyimide sheet or a sheet formed of the perfluoropolymer discussed in connection with
Referring to
Referring to
As discussed above, many embodiments of the present invention include the use of very high temperature E-base polyimide film, layered E-base polyimide film layered with a perfluoropolymer adhesive, perfluoropolymer TE, or combinations thereof. These insulation materials can be susceptible to chemical attack during operation at elevated temperatures. An amino acid can be generated at high temperatures by the epoxy 71 that bonds magnet wires 60 within slots 70 of stator 65 (
A particularly suitable enhanced motor oil that can be used in embodiments of the present invention is commercially available as CL-7VHT oil from Industrial Oils Unlimited. Another suitable commercially available enhanced oil is CL-5VHT oil from Industrial Oils Unlimited. It is also believed that any of the “CL” class of oil having the “VHT” additive from Industrial Oils Unlimited can be used in embodiments of the present invention. In an aspect, any PAO oil having comparable additives as to those used in the “CL” class of oil can be used.
In view of the foregoing, electric submersible pumping systems that are capable of operating in bottom hole temperatures of above about 180° C. (356° F.) are provided as embodiments of the present invention. The elevated temperatures are tolerated by the ESP system by using as insulation either a layered E-base polyimide film layered with a polyimide adhesive, a layered E-base polyimide film layered with a perfluoropolymer adhesive, a perfluoropolymer TE extrusion, or combinations thereof.
This application claims the benefit of provisional application with the U.S. Ser. No. 61/382,355, titled “High Temperature Electric Submersible Pump (ESP) Motor” filed on Sep. 13, 2010, which hereby is incorporated by reference in its entirety.
Number | Name | Date | Kind |
---|---|---|---|
3328512 | Lembke et al. | Jun 1967 | A |
3425865 | Shelton, Jr. | Feb 1969 | A |
5089200 | Chapman et al. | Feb 1992 | A |
5387119 | Wood | Feb 1995 | A |
5426264 | Livingston et al. | Jun 1995 | A |
5477011 | Singles et al. | Dec 1995 | A |
5626907 | Hagiwara et al. | May 1997 | A |
5770779 | Nappa et al. | Jun 1998 | A |
5782301 | Neuroth et al. | Jul 1998 | A |
5859171 | Sawasaki et al. | Jan 1999 | A |
5874171 | Wagner | Feb 1999 | A |
6191208 | Takahashi | Feb 2001 | B1 |
6221970 | Morken et al. | Apr 2001 | B1 |
6281296 | MacLachlan et al. | Aug 2001 | B1 |
6328316 | Fukuhara et al. | Dec 2001 | B1 |
6398585 | Fukuda | Jun 2002 | B1 |
6503972 | Rai et al. | Jan 2003 | B1 |
6548179 | Uhara et al. | Apr 2003 | B2 |
6555238 | Uhara et al. | Apr 2003 | B2 |
6585046 | Neuroth et al. | Jul 2003 | B2 |
6638999 | Bish et al. | Oct 2003 | B2 |
6761544 | McCartney | Jul 2004 | B2 |
6908685 | Uhara et al. | Jun 2005 | B2 |
6969940 | Dalrymple et al. | Nov 2005 | B2 |
6992143 | Wang | Jan 2006 | B2 |
7015396 | Wada et al. | Mar 2006 | B2 |
7354974 | Takahashi et al. | Apr 2008 | B2 |
7439200 | Lee et al. | Oct 2008 | B2 |
7579134 | Dueber et al. | Aug 2009 | B2 |
7611339 | Tetzlaff et al. | Nov 2009 | B2 |
7714231 | Varkey et al. | May 2010 | B2 |
7758781 | Schmeckpeper et al. | Jul 2010 | B2 |
7789689 | Frey et al. | Sep 2010 | B2 |
7854629 | Albers et al. | Dec 2010 | B1 |
20070046115 | Tetzlaff et al. | Mar 2007 | A1 |
20090091202 | Parmeter et al. | Apr 2009 | A1 |
20090317264 | Manke et al. | Dec 2009 | A1 |
20100147505 | Manke et al. | Jun 2010 | A1 |
Entry |
---|
International Search Report and Written Opinion (PCT/US2011/049284), dated Apr. 25, 2012. |
U.S. Appl. No. 12/907,519, filed Oct. 19, 2010. |
DuPont Teflon TE7258 Perfluoropolymer, Resin Extrusion and Molding Resin, 3 pp. |
DuPont Kapton KJ Thermoplastic Polyimide Film, Technical Information, 2 pp. |
DuPont Circleville Research Laboratory, Circleville, Ohio, “Advances in Adhesiveless Substrate Technology for Electronic Packaging”, by Rajan K. Kanakarajan, 3 pp. |
DuPont Kapton EKJ Self-Adhering Polyimide Composite Film, Technical Information, 2 pp. |
DuPont Circleville Research Laboratory, Circleville, Ohio, “New Adhesiveless Substrates for FPC and MCM-L”, by Rajan K. Kanakarajan, EXPO dated Apr. 25, 26, 27, 1994—4 pp. |
DuPont Circleville Research Laboratory, Circleville, Ohio, “Ceramic-Polyimide Systems for Electronic Packaging”, by Rajan K. Kanakarajan and Garry D. Osborn, 7 pp. |
Number | Date | Country | |
---|---|---|---|
20120063933 A1 | Mar 2012 | US |
Number | Date | Country | |
---|---|---|---|
61382355 | Sep 2010 | US |