Patent Publication Number: US-6659174-B2

Title: System and method of tracking use time for electric motors and other components used in a subterranean environment

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The following is based on and claims the priority of provisional application No. 60/275,771 filed Mar. 14, 2001. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to components used in subterranean environments, and by way of example to submersible electric motors that are reused and/or serviced based at least on length of service. 
     BACKGROUND OF THE INVENTION 
     This section is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Electric motors and other components are used in a variety of subterranean applications, such as electric submersible pumping systems. In one example, the submersible motor, along with the rest of the submersible pumping system, may be inserted into a wellbore and lowered until submerged in the desired oil and/or other fluids. The desired fluids collect in the wellbore, and are raised to a point above the earth&#39;s surface via the submersible pumping system powered by the submersible motor. 
     A typical submersible motor, used to pump production fluids from beneath the earth&#39;s surface, has an outer housing substantially sealed from the production fluid environment and sized to fit within standard wellbore casings. An exemplary submersible motor is a three-phase induction-type motor, having a shaft rotatably mounted within the housing such that it is in general alignment with the axis of the wellbore when residing in the wellbore. 
     Power may be supplied to the submersible electric motor via a power cable that runs along the deployment system. Typically, the power cable is banded or supported along either the outside or the inside of the deployment system. Generally, the power cable is routed to the electric motor to supply electric power thereto, and the submersible pump is powered by the motor by way of an appropriate drive shaft. 
     Periodically, the submersible motor, along with the rest of the submersible pumping system, must be removed from the well for movement to another well, for servicing, for replacement, etc. When servicing is required, the submersible motor is disconnected from the remainder of the submersible pumping system and shipped back to the factory or a servicing location. Disassembly of conventional motors sometimes requires the breaking or removal of weldments, making servicing difficult in a field environment. Of course, the cost and delay associated with shipping motors to a servicing center are undesirable. Servicing also can lead to downtime at the well which interrupts production of the petroleum or other wellbore fluid. 
     Attempts have been made to reduce downtime by providing accurate data regarding the service time of the motor. Such data can be useful in estimating remaining life of the motor, need for servicing, the parts that may be required for servicing, etc. 
     In some applications, external recording devices monitor the length of time a given system, e.g. a submersible pumping system, has been in service. However, the data does not apply to individual components, such as motors, once those components have been separated from the system or combined with another system. Additionally, external recording devices cannot capture previous component use. The external recording device only tracks time of use for the overall system once assembled. 
     SUMMARY OF THE INVENTION 
     Certain aspects commensurate in scope with the originally claimed invention are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below. 
     The present invention provides an innovative approach to evaluating and servicing subterranean systems and components, such as electric motors. While the approach may be utilized in a variety of different fields and with different components and systems, an exemplary use is with electric motors used in, for example, submersible pumping systems. The technique incorporates a cyclic event monitor and recorder within the circuitry of a device, such as an electric motor. 
     The addition of a recording device within an electric motor limits service-reporting errors and decreases down time of the motor. Therefore, with an internal cyclic event monitor and recorder, the time to failure estimates and quality considerations stay within the confines of the product. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other advantages and features of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
     FIG. 1 is a front, elevational view of a submersible pumping system, according to an exemplary embodiment of the present invention; 
     FIG. 2 is a schematic view of an electric submersible motor, according to an exemplary embodiment of the present invention; 
     FIG. 3 is a block diagram representing an electric submersible motor illustrated in FIG. 2; and 
     FIG. 4 is a block diagram illustrating the coupling of a power supply to the recording device, according to an exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     One or more embodiments of the present invention are described below. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. The descriptions following are by way of example only illustrating embodiments of the present invention. The method and apparatus of the present invention may be applied in a similar manner in other embodiments, without departing from the spirit of the invention. 
     Referring generally to FIG. 1, an exemplary pumping system  10 , such as an electric submersible pumping system, is illustrated. Pumping system  10  may comprise a variety of components depending on the particular application or environment in which it is used. Typically, system  10  includes at least a pump  12 , such as a centrifugal pump, a motor  14  and a motor protector  16 . 
     In the illustrated example, pumping system  10  is designed for deployment in a well  18  within a geological formation  20  containing desirable production fluids, such as petroleum. In an exemplary application, a wellbore  22  is drilled into geological formation  20  and lined with a wellbore casing  24 . Wellbore casing  24  may include a plurality of openings  26  through which production fluids may flow into wellbore  22 . 
     Pumping system  10  is deployed in wellbore  22  by a deployment system  28  that may have a variety of forms and configurations. For example, deployment system  28  may comprise tubing  30  connected to pump  12  by an appropriate connector  32 . Power is provided to submergible motor  14  via a power cable  34 . Motor  14 , in turn, powers centrifugal pump  12  which draws production fluid in through a pump intake  36  and pumps the production fluid to the surface or other location via tubing  30 . 
     It should be noted that the illustrated submersible pumping system is merely an exemplary embodiment. Other components can be added to this system, and other deployment systems may be implemented. Additionally, a variety of motors  14  can be used to power to downhole pumping system or other type of downhole system. In any of these configurations, it may be desirable to track the uselife of a component, such as motor  14 . 
     Components of submersible pumping system  10  are particularly well suited for a data recording system  40  utilizing a cyclic event monitor  42 . It will be appreciated by those skilled in the art that the unique features of a system component, e.g. motor  14 , in combination with recorder  40  and cyclic event monitor  42  may be adapted for use in any system for tracking the uselife of the component. Tracking of uselife can be beneficial for a variety of components, but it is particularly amendable for tracking uselife of submersible motors. 
     As illustrated in FIG. 2, an exemplary submersible motor  14  is the 562 series motor manufactured under the tradename REDA for Schlumberger Corporation. The 562 series motor is a three-phase, induction-type motor, but the present invention can be adapted to a variety of submersible motors of various sizes, diameters, and designs. FIG. 2 generally illustrates a submersible electric motor  14  having an external housing  44  through which power cable  34  extends. The electric motor  14  generally comprises a stator  46 , a rotor  48 , and recording device  40 . 
     Recording device  40  may have a variety of forms, but typically is coupled to cyclic event monitor  42  which, in one embodiment, comprises a timing circuit. The cyclic event monitor  42  tracks the uselife of electric motor  14  regardless of whether motor  14  is combined into a different system and/or application. The recording device  40  may comprise, for example, a memory chip to store data from cyclic event monitor  42 . The cyclic event monitor  42  may have a variety of forms, as would be recognized by one of ordinary skill in the art. For example, cyclic event monitor  42  may comprise a chip having a timing circuit activated upon activation of motor  14  to provide an output to recording device  40  which records the actual time of use of motor  14 . 
     Alternatively, the timing circuit/cyclic event monitor  42  can be designed to count the revolutions of the rotor  48  by sensing, for example, a magnet affixed to rotor  48 . The cyclic event monitor can take the form of a chip, a hardwired circuit, a mechanical counter or a variety of other forms depending on the specific design of electric motor  14 . Additionally, cyclic event monitor  42  can be mounted in other types of components, e.g. pumps, motor protectors, etc., to track the total time of use of the individual component. 
     In one embodiment, recording device  40  and cyclic event monitor  42  comprise a mechanical counter and recorder able to count and record, for example, the shaft revolutions of the component. The mechanical counter can be designed similar to an odometer that is mechanically or otherwise connected to the rotatable portion of the component. Such mechanical counters and recorders are amenable to use with components that do not receive electrical power, e.g. pumps, motor protectors, etc. 
     As illustrated in the block diagram of FIG. 3, recording device  40  may be designed to transmit data via a transmitter  50  to a control unit  52 . The control unit  52  may be any type of system whereby data can be stored and analyzed. The control unit  52  may be coupled to the transmitter  50  through a conduit or it can be wireless. In this embodiment, a recording device  40  is shown internal to the electric motor. In another embodiment the recording device  40  may be coupled to the electric motor  12  through a wireless system. 
     Referring generally to FIG. 4, a block diagram of a power system  60  of an exemplary of a submersible pumping system  10  is illustrated. A power circuit  62  external of the submersible motor  14  is couplable to a direct current bus  64 . The direct current bus  64  allows the power circuit  62  to provide power to the electric motor  14  and the recording device  40 . Recording device  40 , in turn, is coupled to transmitter  50 , which transmits data to control unit  52 . 
     The cyclic event monitor  42  also may be disposed within the recording device  40  or separate from recording device  40 . In this embodiment, power is supplied through the power cable  34  to submersible motor  14  and serves to activate recording device  40  and cyclic event monitor  42 . Current passes through the circuitry of the electric motor  14  activating device  40  and cyclic event monitor  42 . When the monitor  42  is activated, recording device  40  maintains total time of use data concerning the use of the electric motor  14 . As described above, this data is sent through transmitter  50  to control unit  52 , where the data may be stored and analyzed. 
     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.