Abstract:
A positive displacement pump is provided that includes a pump housing having a pump chamber; a plunger mounted in the pump housing for reciprocating motion in the pump chamber; a suction valve positioned to allow a fluid to enter the pump chamber upon movement of the plunger in a first direction; a discharge valve positioned to discharge the fluid from the pump chamber upon movement of the plunger in a second direction; and at least one sensor enclosed by the pump housing for measuring at least one pump condition parameter.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and is a Continuation-In-Part of U.S. patent application Ser. No. 11/312,124, filed on Dec. 20, 2005, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to a sensor system for use in a positive displacement pump, and more particularly to such a sensor system mounted within the positive displacement pump. 
       BACKGROUND 
       [0003]    Generally, positive displacement pumps, sometimes referred to as reciprocating pumps, are used to pump fluids in a variety of well applications. For example, a reciprocating pump may be deployed to pump fluid into a wellbore and the surrounding reservoir. The reciprocating pump is powered by a rotating crankshaft which imparts reciprocating motion to the pump. This reciprocating motion is converted to a pumping action for producing the desired fluid. 
         [0004]    A given reciprocating pump may include one or more pump chambers that each receive a reciprocating plunger. As the plunger is moved in one direction by the rotating crankshaft, fluid is drawn into the pump chamber through a one-way suction valve. Upon reversal of the plunger motion, the suction valve is closed and the fluid is forced outwardly through a discharge valve. The continued reciprocation of the plunger continues the process of drawing fluid into the pump and discharging fluid from the pump. The discharged fluid can be routed through tubing to a desired location, such as into a wellbore. 
         [0005]    As is often the case with large systems and industrial equipment, regular monitoring and maintenance of positive displacement pumps may be sought to help ensure uptime and increase efficiency. Accordingly, a need exist for an improved monitoring system for a positive displacement pump. 
       SUMMARY 
       [0006]    In one embodiment, the present invention is a positive displacement pump that includes a pump housing having a pump chamber; a plunger mounted in the pump housing for reciprocating motion in the pump chamber; a suction valve positioned to allow a fluid to enter the pump chamber upon movement of the plunger in a first direction; a discharge valve positioned to discharge the fluid from the pump chamber upon movement of the plunger in a second direction; and at least one sensor enclosed by the pump housing for measuring at least one pump condition parameter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
           [0008]      FIG. 1  is a schematic illustration of a pumping system for use in a well operation according to one embodiment of the present invention; 
           [0009]      FIG. 2  is a schematic illustration of a various sensors coupled to a control system for use in the pumping system of  FIG. 1 ; 
           [0010]      FIG. 3  is a cross-sectional view of a positive displacement pump that can be used in the system illustrated in  FIG. 1 , according to an embodiment of the present invention; 
           [0011]      FIG. 4  is close up view taken from detail  4  of  FIG. 3 , showing the interaction of a valve with a valve seat; and 
           [0012]      FIG. 5  is close up view of the valve and valve seat of  FIG. 4  shown with degradation of both the valve and the valve seat. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. 
         [0014]    As such in  FIGS. 1-5  embodiments of the present invention relate to a system and methodology for providing optimal use of a positive displacement pump deployed, for example, in a well related system. In one aspect, a sensor system is located within the positive displacement pump to detect vital pump condition parameters. These parameters can be transferred to a control system at the surface of the well, which can interpret the parameters and determine the pump&#39;s condition. This control system can also predict when maintenance or part replacements are needed. 
         [0015]    In one embodiment, the sensor system includes one or more sensors that are self powered using the pump motion, the pump vibration, or another appropriate energy source from the pump, as a power source. As used herein, a self-powered device is a device powered by a means other than a battery or an external power cord. For example, a self powering mechanism of a sensor according to the present invention may include a magnet-coil assembly or a piezoelectric material, among other appropriate self powering mechanisms. 
         [0016]    In one embodiment described herein, the sensor system is used to obtain data on pump condition parameters that indicate abnormal events during pumping or degradation of suction valves and/or discharge valves within the pump. The determination of valve wear can be indicative of a failure mode, and the data can be used in predicting failure of the component. Examples of abnormal events that occur during pumping include pump cavitation, loss of prime, valves stuck in an open or closed position, and debris interfering with valve closure. 
         [0017]    Referring generally to  FIG. 1 , a system  20  is illustrated for use in a well application, according to one embodiment of the present invention. It should be noted that the present system and method can be used in a variety of applications. As such, the illustrated well application is merely used as an example to facilitate explanation. In the illustrated embodiment, the system  20  includes, for example, a positive displacement pump, i.e. a reciprocating pump  22 , deployed for pumping a fluid into a well  24  having a wellbore  26  drilled into a reservoir  28  containing desirable fluids, such as hydrocarbon based fluids. 
         [0018]    In many applications, the wellbore  26  is lined with a wellbore casing  30  having perforations  32  through which fluids can flow between the wellbore  26  and the reservoir  28 . The reciprocating pump  22  may be located at a surface location  34 , such as on a truck or other vehicle  35 , to pump fluid into the wellbore  26  through the tubing  36  and out into the reservoir  28  through the perforations  32 . By way of example, the well application may include pumping a well stimulation fluid into the reservoir  28  during a well stimulation operation, e.g. pumping a fracturing fluid into the well. 
         [0019]    In the embodiment illustrated in  FIG. 1 , the positive displacement pump  22  is coupled to a control system  40  by one or more communication lines  42 . The communication line(s)  42  can be used to carry signals between the positive displacement pump  22  and the control system  40 . For example, data from sensors located within the pump  22  can be output through communication lines  42  for processing by control system  40 . The form of communication lines  42  may vary depending on the design of the communication system. For example, the communication system may be formed as a hardwired system in which communication lines  42  are electrical and/or fiber-optic lines. 
         [0020]    Alternatively, the communication system may include a wireless system in which communication lines  42  are wireless and able to provide wireless communication of signals between the pump sensors and the control system  40 . An advantage of the wireless communication system is that it lacks wires, which if present could be inadvertently moved and/or dislodged from a desired location due to human interaction or due to movements or vibrations caused by the mere operation of the pump. 
         [0021]    Referring to  FIG. 2 , the control system  40  may be a processor based control system able to process data received from a sensor system  44  deployed within the pump  22 . By way of example, the control system  40  may be a computer-based system having a central processing unit (CPU)  46 . In one embodiment, the CPU  46  is operatively coupled to a memory device  48 , as well as an input device and an output device  52 . The input device  50  may include a variety of devices, such as a keyboard, a mouse, a voice-recognition unit, a touch-screen, among other input devices, or combinations of such devices. The output device  52  may include a visual and/or audio output device, such as a monitor having a graphical user interface. Additionally, the processing may be done on a single device or multiple devices at the well location, away from the well location, or with some devices located at the well and other devices located remotely. 
         [0022]    The sensor system  44  is designed to detect specific parameters associated with the operation of the positive displacement pump  22 . Data related to the specific parameters is output by the sensor system  44  through communication line or lines  42  to the control system  40  for processing and evaluation (note again that in one embodiment this communication is wireless.) The pump parameter data is used to determine possible failure modes through indications of pump malfunctions, such as pump component degradations, e.g. pump valve or valve seat degradation. 
         [0023]    The control system  40  also can be used to evaluate and predict an estimated time to failure using techniques, such as data regression. As will be explained more fully below, the sensor system  44  may include one or more sensors located within the positive displacement pump  22 . Examples of such sensors include a pump chamber sensor  54 , a plunger sensor  55 , a pump housing sensor  56 , a valve insert sensor  57 , and a valve seat sensor  58 . 
         [0024]    A positive displacement pump  22  according to one embodiment of the present invention is illustrated in  FIG. 3 . As illustrated, the pump  22  includes a pump housing  62  having a pump chamber  64 . A plunger  66  is slidably mounted within pump housing  62  for reciprocating motion within the pump chamber  64 . The reciprocating motion of the plunger  66  acts to change the volume of the pump chamber  64 . The pump  22  further includes check valves, such as a suction valve  68  and a discharge valve  70 , that control the flow of fluid into and out of the pump chamber  64  as the plunger  66  reciprocates. 
         [0025]    The reciprocating motion of the plunger  66  may be generated by a rotating crankshaft (not shown), as known to those of ordinary skill in the art. It should also be noted that a single plunger and a single pump chamber are illustrated to facilitate explanation. However, the illustrated single plunger and single pump chamber also are representative of potential additional plungers and pump chambers along with their associated check valves. For example, the illustrated single plunger and single pump chamber may form a portion of a three chamber, triplex pump. With a triplex pump or other multiple chamber pumps, the motion of the plungers can be staggered to achieve a more uniform flow of pumped fluids, making such pumps desirable in a number of pumping applications. 
         [0026]    The suction valve  68  and the discharge valve  70  are actuated by fluid and spring forces. The suction valve  68 , for example, is biased toward a suction valve seat  72 , i.e. toward a closed position, by a spring  74  positioned between the suction valve  68  and a spring stop  76 . Similarly, the discharge valve  70  is biased toward a discharge valve seat  78 , i.e. toward a closed position, by a discharge valve spring  80  positioned between the discharge valve  70  and a spring stop  82 . 
         [0027]    As shown, the suction valve  68  further includes a sealing surface  84  oriented for sealing engagement with the valve seat  72 . The sealing surface  84  of the valve  68  includes a strike face  86 , that may be formed of a metal, and a flexible portion that may be formed as a flexible valve insert  88 . The flexible valve insert  88  may be slightly raised relative to the strike face  86 . 
         [0028]    Similarly, the discharge valve  70  includes a sealing surface  90  oriented for sealing engagement with the valve seat  78 . The sealing surface  90  of the valve  70  includes a strike face  92 , that may be formed of a metal, and a flexible portion that may be formed as a flexible valve insert  94 . The flexible valve insert  94  may be slightly raised relative to strike face  92 . 
         [0029]    When the plunger  66  moves outwardly (to the left in  FIG. 3 ), a drop in pressure is created within the pump chamber  64 . This drop in pressure causes the suction valve to move against the bias of spring  74  to an open position and causes fluid to flow into pump chamber  64  through the suction valve  68 . This phase can be referred to as the “suction stroke.” When the plunger  66  moves in a reverse direction (to the right in  FIG. 3 ), the suction valve  68  is closed by the spring  74 , and pressure is increased in the pump chamber  64 . The increase in pressure causes the discharge valve  70  to open and forces fluid from the pump chamber  64  outwardly through discharge valve  70 . The discharge valve  70  remains open while the plunger  66  continues to apply pressure to the fluid in the pump chamber  64 . The high-pressure phase in which fluid is discharged through the discharge valve  70  is known as the “discharge stroke.” 
         [0030]    As each valve  68 , 70  is closed, its valve insert  88 , 94  contacts its corresponding seat  72 , 78  and is compressed until the strike face  86 , 92  of the valve  68 , 70  also makes contact with the seat  72 , 78 . With the suction valve  68 , for example, the valve insert  88  is compressed against the valve seat  72  until the strike face  86  contacts the valve seat  72 . This normally occurs shortly after initiation of the discharge stroke. With the discharge valve  70 , the valve insert  94  is compressed against the valve seat  78  until the strike face  92  contacts the valve seat  78 . This normally occurs shortly after initiation of the suction stroke. 
         [0031]    The flexible valve inserts  88 , 94  are beneficial for environments in which fluid containing an abrasive material, such as sand, or other particulates is pumped. Typically, the valve inserts  88 , 94  are composed of urethane or some other conventional deformable polymer. The deformation of the flexible valve inserts  88 , 94  enables the valves  68 , 70  to seal even when fluids containing particles, for example cement particles, sand or proppant, are moved through the pump  22 . However, the abrasive action of such particulates during extended use of the valves  68 , 70  causes the flexible valve inserts  88 , 94  to degrade, which reduces the ability of the valves  68 , 70  to form a seal and ultimately leads to valve failure and pump malfunction. In one embodiment, the valve inserts  88 , 94  are made of urethane or another conventional polymers. 
         [0032]    However, the valve inserts  88 , 94  may not be necessary in applications involving the pumping of relatively “clean” or “non-abrasive” fluids. In such applications, the sealing surfaces  84 , 90  of the valves  68 , 70  can be formed without the valve inserts  88 , 94  such that sealing is accomplished only between the metal strike face  86 , 92  of the valves  68 , 70  and the valve seats  72 , 78 . In embodiments where the valves  68 , 70  are designed without the flexible valve inserts  88 , 94 , the metal strike faces  86 , 92  of the valves  68 , 70  may still degrade with repeated use, although typically not as quickly. 
         [0033]    As such, the sensor system  44  is incorporated into the pump  22  to detect pump condition parameters which can be used to determine component wear or degradation, and/or other pump malfunctions. In one embodiment, the sensor system  44  is used to detect wear on the suction and/or discharge valves  68 , 70  through the use of sensors positioned at various locations within the positive displacement pump  22 . 
         [0034]    For example, in one embodiment the sensor system  44  includes a pump chamber sensor  54  mounted on a face of the plunger  66  at a position adjacent to the pump chamber  64  to allow for continued exposure of the sensor  54  to the pump chamber  64  and the fluid disposed therein. At such a position, the sensor  54  may measure the pump chamber pressure, temperature and/or vibration, among other desired parameters. Such a sensor  54  may be self powered using energy from the motion of the plunger  66 . The pump chamber sensor  54  may include any appropriate sensor, such as a pressure sensor, a temperature sensor, or an accelerometer, among other appropriate sensors. 
         [0035]    The sensor system  44  may include a plunger sensor  55  mounted on or inside the plunger  66 . At such a position, the plunger sensor  55  may measure the position of the plunger  66 , among other desired parameters. Such a plunger sensor  55  may be self powered using energy from the motion of the plunger  66 . The plunger sensor  55  may include any appropriate sensor, such as an accelerometer or a proximity switch, among other appropriate sensors. 
         [0036]    The sensor system  44  may include a pump housing sensor mounted on or within an interior wall of the pump housing  62 . Although  FIG. 3  shows two possible locations of the pump housing sensor  56 , in one embodiment the pump housing sensor  56  may be mounted at any position along the interior wall of the pump housing  62  as long as it is adjacent to the pump chamber  64 . The pump housing sensor may measure the pump chamber pressure, temperature and/or vibration, among other desired parameters. 
         [0037]    Note that in order to measure the pump chamber pressure, it is advantageous for the pump housing sensor  56  to be positioned such that it may contact fluid within the pump chamber  64 . The pump housing sensor  56  may be self powered using stress from the energized fluid within the pump chamber  60 . The pump housing sensor  56  may include any appropriate sensor, such as a pressure sensor, a temperature sensor, or an accelerometer among other appropriate sensors. 
         [0038]    As shown in  FIGS. 4 and 5 , the sensor system  44  may include a valve insert sensor  57  mounted on or within the flexible valve inserts  88 , 94  of either or both of the valves  68 , 70 . The valve insert sensor  57  measures a degradation  25  (see  FIG. 5 ) or a wearing away of the valve insert  88 , 94  to which it is attached. 
         [0039]    Typically, the valve insert  88 , 94  is composed of an insulator, and the valve seat  72 , 78  is composed of a conductor. In such an embodiment, the valve insert sensor may be a sensor that measures conductivity between itself and another conductor, such as an electrical resistivity sensor or a voltage sensor, among other appropriate sensors. 
         [0040]    As such, in this embodiment, the valve insert sensor  57  is embedded in the valve insert  88 , 94  at a position such that when the valve insert  88 , 94  is not degraded (as shown in  FIG. 4 ) or at least when the valve insert  88 , 94  is degraded to an acceptable level, the valve insert sensor  57  does not contact the valve seat  72 , 78  and therefore cannot measure a conductivity therebetween; and when the valve insert  88 , 94  is degraded to an undesirable level (as shown in  FIG. 5  and indicated by degraded section  25 ), the valve insert sensor  57  contacts the valve seat  72 , 78  and measures a conductivity therebetween. At such a time, the valve insert sensor  57  may send a signal to the control system  40  indicating an undesirably worn valve insert  88 , 94 . 
         [0041]    Additionally or in the alternative, the valve insert sensor  57  may be configured to measure a conductivity between itself and the fluid being pumped. Such a situation occurs when the end of the sensor  57  is exposed and in contact with the fluid being pumped, but not yet exposed to the extend allowing the sensor  57  to contact the valve seat  72 , 78 . 
         [0042]    In another embodiment, the valve insert sensor  57  measures the integrity of itself. When the integrity is damaged to a predetermined condition, then the control system  40  determines that the valve insert  88 , 94  is undesirably worn. In either embodiment, the valve insert sensor  57  can be self powered by the stress from the valve insert  88 , 94  deformation. 
         [0043]    As is also shown in  FIGS. 4 and 5 , the sensor system  44  may include a valve seat sensor  58  mounted on or within the valves seat  72 , 78 . The valve seat sensor  58  measures a degradation  27  (see  FIG. 5 ) or a wearing away of the valve seat  72 , 78  to which it is attached. 
         [0044]    Typically, the valve seat  72 , 78  is composed of a conductor, and the strike face  86 , 92  of the valve  68 , 70  is composed of a conductor. In such an embodiment, the valve seat sensor  58  may be a sensor that measures conductivity between itself and another conductor, such as an electrical resistivity sensor or a voltage sensor, among other appropriate sensors. 
         [0045]    As such, in this embodiment, the valve seat sensor  58  is encased, at least partially, in an insulator  59 ; and the sensor  58  and the insulator  59  are embedded in the valve seat  72 , 78  at a position such that when the valve seat  72 , 78  is not degraded (as shown in  FIG. 4 ) or at least when the valve seat  72 , 78  is degraded to an acceptable level, the valve seat sensor  58  does not contact the strike face  86 , 92  of the valve  68 , 70  and therefore cannot measure a conductivity therebetween; and when the valve seat  72 , 78  is degraded to an undesirable level (as shown in  FIG. 5  and indicated by degraded section  27 ), which is quickly followed by a degradation of the insulator  59 , the valve seat sensor  58  contacts the valve seat  72 , 78  and measures a conductivity therebetween. At such time, the valve seat sensor  58  may send a signal to the control system  40  indicating an undesirably worn valve seat  72 , 78 . 
         [0046]    Additionally or in the alternative, the valve seat sensor  58  may be configured to measure a conductivity between itself and the fluid being pumped. Such a situation occurs when the end of the sensor  58  is exposed and in contact with the fluid being pumped, but not yet exposed to the extend allowing the sensor  58  to contact the strike face  86 , 92  of the valve  68 , 70 . 
         [0047]    In another embodiment, the valve seat sensor  58  measures the integrity of itself. When the integrity is damaged to a predetermined condition, then the control system  40  determines that the valve insert  88 , 94  is undesirably worn. In either embodiment, the valve seat sensor  58  can be self powered by the stress from the valve seat  72 , 78  deformation, or the valve seat sensor  58  can be battery powered and operated in a low-bandwidth mode. 
         [0048]    Any one or all of the sensors  54 - 58  may be mounted within the pump housing  62  ( FIG. 3  shows each of the sensors  54 - 58  mounted within the pump housing  62 ) to protect the sensors  54 - 58  from the environment external to the pump housing  62  and to protect the sensors  54 - 58  from inadvertent movement or dislodgement of the sensors  54 - 58 , such as by inadvertent human contact. 
         [0049]    As eluded to above, any one or all of the sensors  54 - 58  may communicate with the control system  40  wirelessly. Wireless communication between the sensors  54 - 58  and the control system  40  lessens the likelihood of the sensors  54 - 58  being inadvertently moved and/or dislodged from a desired location due to inadvertently human contact or due to movements or vibrations caused by the mere operation of the pump  22 . 
         [0050]    As described above, a plurality of pump parameters detected within a positive displacement pump can be used individually or in combination to determine indications of pump component degradation. It should be noted that different types of sensors can be used in pump  22 , and those sensors can be located at a variety of locations within the pump depending on, for example, pump design, well environment and sensor capability. Additionally, the sensor or sensors may be deployed in pumps having a single pump chamber or in pumps having a plurality of pump chambers to provide data for determining degradation of valves associated with each pump chamber and/or other pump malfunctions. Note that the sensors  54 - 58  are shown schematically in  FIGS. 1-5  and are not necessarily drawn to scale. 
         [0051]    The preceding description has been presented with reference to presently preferred embodiments of the invention. Persons skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, and scope of this invention. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.