US20120020808A1 - Wireless Monitoring of Pump Jack Sucker Rod Loading and Position - Google Patents

Abstract

Forces on and respective positions of a pump jack sucker rod are determined in real time by load cells attached to the sucker rod and a position sensor, and are stored for further processing. A wireless transmitter transmits stored load and position values, calculated process parameters, and/or exception alerts to a wireless spread spectrum receiver that can be coupled to a motor speed controller used to set the rotational speed of the pump jack motor, and/or to monitoring systems, such as a central controller used to optimize total field production.

Description

RELATED PATENT APPLICATION
• This application claims priority to commonly owned U.S. Provisional Patent Application Ser. No. 61/165,628; filed Apr. 1, 2009; entitled “Wireless Monitoring Of Pump Jack Sucker Rod Loading And Position,” by Rick A. Lawson and Doneil Dorado; and is hereby incorporated by reference herein for all purposes.
TECHNICAL FIELD
• The present disclosure relates to oil well pump jacks and, more particularly, to monitoring and control of the pump jacks to optimize pumping operation of the pump jacks in producing production from the oil wells.
BACKGROUND
• Historically, oil wells which must produce by artificial lift have used horsehead-type pumping units such as those made by Lufkin Industries and others. To counterbalance the weight of the sucker rod string, counterweights are used, either mounted on the walking beam or a rotary-type mounted on the gear box Pittman arm. Another class of pumping unit (also made by Lufkin) uses an air cylinder in place of the metal counterweights. The effect is roughly the same. The sucker rod string reciprocates up and down in a sine wave motion caused by rotation of the Pittman arm by an electric motor.
• The electric motor drives the pumping jack sucker rod string on as to lift oil in discreet slugs or pulses from a pocket at the bottom of the well bore to the surface. Such a pumping system typically comprises a power driven jack or beam which reciprocates on a pivot to reciprocate a string of well (sucker) rod up and down in the well casing, and thereby provide a lifting or pumping action that delivers the crude oil and brine from the well pocket to the well head at the surface and thereafter storage.
• The rate at which the crude oil in an oil well migrates to the well bore and fills the well pocket may vary widely from one well to another depending upon specific geologic conditions in the oil bearing sands, and the age of the oil field in terms of the proportion of recoverable crude oil which has been removed from the geologic formations. In mature wells, commonly known as stripper wells, the maximum attainable production rate will depend entirely on how quickly the spontaneous migration of crude oil to the well pocket can fill the pocket. Typically, in such wells the pumping capacity of the pumping jack is far greater than the capacity of the field to refill well pocket with crude oil from the oil bearing formations. Even in newer, more productive wells the pumping capacity of the pumping jack may far exceed spontaneous well pocket refill rates.
• To accommodate these well pocket refill rates and other limitations of oil well production, the rotational speed of the electric motor is controlled so as to optimize fluid pumping action by the well sucker rod string of the pumping jack, so that pumping action is not too fast or too slow.
• A pump motor speed controller is used to control the pumping action of the pump jack from various parameters of the pump jack. For example, the well sucker rod string load (up and down) and rotational speed of the pump motor may be used in determining optimal pumping action, and/or to alert for undesirable conditions in the well.
• FIG. 1 illustrates a schematic elevational diagram of a prior technology pump jack system having hardwired sucker rod load and position sensors, and connected to a well sucker rod string. The pump jack system, represented by thenumeral100, comprises asucker rod string110, apolish rod120, ahorsehead122, arocker beam124, connectingrod132,counter weight134, Pittmanarm136, motor/gear drive138,frame128 andbase146. As the motor/gear drive138 rotates, the Pittmanarm136 causes the connectingrod132 to push up or pull down one end of therocker beam124. On the other end of therocker beam124 is thehorsehead122 connected to thepolish rod120. As thehorsehead122 moves up and down so does thepolish rod120 which in turn moves thesucker rod string110 in and out of the well borepipe118. The wellbore pipe118 is terminated at flange/fluid takeoff assembly116 that is adapted to allow fluid (or gas) being pumped out of the wellbore pipe118 to flow to a storage tank/pipeline (not shown). The flange/fluid takeoff assembly116 also is used to seal around a portion of thesucker rod string110 so that well fluid does not spill onto the ground.
• Axial forces on thesucker rod string110 may be measured by aload cell114 that determines the axial forces applied to thesucker rod string110 when being draw upwards and when being pushed downward. Theload cell114 accomplishes these measurements by being held in a fixed position on thesucker rod string110 between atop clamp collar112aand abottom clamp collar112b.
• The vertical position of thesucker rod string110 relative to the down hole well pocket may be determined by positional information from arotation position sensor140, e.g., Hall effect device, that indicates the rotational position of the Pittmanarm136. The vertical position of thesucker rod string110 may then be correlated with the rotational position of the Pittmanarm136. Once thesucker rod string110 axial forces and associated vertical positions are available, a determination can be made for a desired rotational speed(s) of the motor/gear drive138 to optimize well fluid pumping action. Note that the rotational speed can be varied during a pumping cycle (360 degree rotation of the Pittman arm136) to further optimize the well fluid pumping action.
• Theload cell114 may be electrically coupled to amotor speed controller144 through a flexible electrical cable126 that may be attached to theframe128 with a junction/strain relief box130. Therotation position sensor140 may be electrically coupled to themotor speed controller144 through an electrical conduit orcable142. The electrical cable126 may be routed over thehorsehead122 and across therocker beam124.
• Flexibility of the electrical cable126 is very important in that theload cell114 is constantly moving up and down. However this constant flexing of the electrical cable126 causes failures thereto that requires maintenance and replacement in the field. Also therotation position sensor140 is subject to failure and also requires periodic maintenance and/or replacement. Working in close proximity to the Pittmanarm136 when servicing therotation position sensor140 poses serious safety issues and careless field service technicians have been injured, some severely, by coming in contact with a Pittmanarm136 that accidentally starts to rotate while service/replacement of theposition sensor140 is being performed. Thus, service, reliability and safety problems exist in present technology load and position measurement installations and servicing of pump jack systems, specifically for fatigue of the connecting electrical cables and the hazards of accidental rotation of machinery while servicing sensors in close proximity thereto.
SUMMARY
• Therefore a need exists to overcome the above-identified problems as well as other shortcomings and deficiencies of existing technologies by providing wireless transmission of data from sucker rod load and position sensors, and then using that data to control the pump jack system operating parameters so as to optimize fluid lift from the well pocket.
• According to the teachings of this disclosure, a wireless sensor package is mechanically and electrically attached to theload cell114, and moves therewith. The wireless sensor package comprises an electrical interface for receiving electrical signals from theload cell114, and a position sensor, e.g., a tri-axial accelerometer, or device for measuring distance from a fixed point, e.g., ultrasonic, radio frequency, infrared, laser light, etc. In addition, a downhole temperature gradient may be determined by measurement of the elongation of the wellbore pipe118 projecting out of the ground (e.g., distance from ground level to the top of the well bore pipe118). Well pressure and flow rate may also be measured at the flange/fluid takeoff assembly116.
• The wireless sensor package is adapted to transmit the sucker rod load and position information over a radio frequency channel(s), e.g., short-range radio, for example but not limited to, frequencies at about 315 MHz, 433 MHz, 868 MHz, 902 to 928 MHZ, 2.4 to 2.5 GHz, 5.7 to 5.8 GHz, etc. In addition, any form of transmission and modulation techniques may be used, for example but not limited to, spread spectrum to a compatible receive, e.g., spread spectrum receiver, coupled to a motor speed controller. Computations for optimal motor speeds from the wireless load and position data may be performed in the wireless sensor package and/or the wireless motor speed controller. A central controller receiving load and position information and/or motor speeds from each of the plurality of pump jacks may further be used to control pump speeds of the plurality of jump jacks so as to optimize oil field production, e.g., flow rates of pumped product. The central controller may also determine optimal pumping parameters of each of the plurality of pump jacks so as to maximize oil field production.
• According to a specific example embodiment of this disclosure, a pump jack adapted for monitoring sucker rod load and position comprises: a sucker rod string in a well bore pipe; a polished rod coupled to the sucker rod string; a horsehead coupled to the polished rod; a rocker beam coupled to the horsehead; a connecting rod coupled to the rocker beam; a counter weight coupled to the connecting rod; a pittman arm coupled to the connecting rod and counter weight; a variable speed motor-gear drive assembly coupled to the pittman arm for rotational movement thereof; a frame pivotally coupled to the rocker beam; a base attached to the frame; first and second force sensors attached to a proximate end of the sucker rod string, wherein the first and second force sensors measure elongation and compression stresses, respectively, of the sucker rod string while the sucker rod string moves up and down in the well bore pipe; a position sensor attached toward the proximate end of the sucker rod string, wherein the position sensor determines positions of the sucker rod string; a sensor interface assembly having wireless transmitting capabilities, wherein the sensor interface assembly is attached to the sucker rod string, and is coupled to the first and second force measurement sensors and the position sensor, whereby the sucker rod string forces and position information are wirelessly transmitted therefrom; and a wireless receiver coupled to the variable speed motor-gear drive assembly, wherein the wireless receiver receives the force and position information transmitted from the interface assembly for determining control of rotational speed of the variable speed motor-gear drive assembly.
• According to another specific example embodiment of this disclosure, an apparatus for monitoring position and load of a sucker rod in a pump jack, comprises: first and second force sensors attached at a proximate end of a sucker rod string of a pump jack, wherein the first and second force sensors measure elongation and compression stresses, respectively, of the sucker rod string while the sucker rod string moves up and down in a well bore pipe; a position sensor attached toward the proximate end the sucker rod string, wherein the position sensor determines positions of the sucker rod string; and a sensor interface assembly having wireless transmitting capabilities, wherein the sensor interface assembly is attached to the sucker rod string, and is coupled to the first and second force measurement sensors and the position sensor, whereby the sucker rod string forces and position information are wirelessly transmitted therefrom.
• According to still another specific example embodiment of this disclosure, a pump jack adapted for monitoring sucker rod load and position comprises: a sucker rod string in a well bore pipe; a polished rod coupled to the sucker rod string; a horsehead coupled to the polished rod; a rocker beam coupled to the horsehead; a connecting rod coupled to the rocker beam; a counter weight coupled to the connecting rod; a pittman arm coupled to the connecting rod and counter weight; a variable speed motor-gear drive assembly coupled to the pittman arm for rotational movement thereof; a frame pivotally coupled to the rocker beam; abuse attached to the frame; first and second force sensors attached to a proximate end of the sucker rod string, wherein the first and second force sensors measure elongation and compression stresses, respectively, of the sucker rod string while the sucker rod string moves up and down in the well bore pipe; a sensor interface assembly having wireless transmitting capabilities, wherein the sensor interface assembly is attached to the sucker rod string, and is coupled to the first and second force measurement sensors, whereby the sucker rod string force information is wirelessly transmitted therefrom; a distance measuring device attached on a plan of the base and under the sensor interface assembly, wherein the position sensor determines positions of the sucker rod string by measuring distances between the distance measuring device and the sensor interface assembly; and a wireless receiver coupled to the variable speed motor-gear drive assembly, wherein the wireless receiver receives the force information transmitted from the sensor interface assembly, and wherein position information from the distance measuring device is coupled to the variable speed motor-gear drive assembly, whereby control of rotational speed of the variable speed motor-gear drive assembly is determined from the force and position information.
• According to yet another specific example embodiment of this disclosure, an apparatus for monitoring position and load of a sucker rod in a pump jack comprises: first and second force sensors attached at a proximate end of a sucker rod string of a pump jack, wherein the first and second force sensors measure elongation and compression stresses, respectively, of the sucker rod string while the sucker rod string moves up and down in a well bore pipe; a sensor interface assembly having wireless transmitting capabilities, wherein the sensor interface assembly is attached to the sucker rod string, and is coupled to the first and second force measurement sensors, whereby the sucker rod string force information is wirelessly transmitted therefrom; a distance measuring device attached on a plane of a base of the pump jack and under the sensor interface assembly, wherein the distance measuring device determines positions of the sucker rod string by measuring distances between the distance measuring device and the sensor interface assembly; and a wireless receiver coupled to the variable speed motor-gear drive assembly, wherein the wireless receiver receives the force information transmitted from the sensor interface assembly, and wherein position information from the distance measuring device is coupled to the variable speed motor-gear drive assembly, whereby control of rotational speed of the variable speed motor-gear drive assembly is determined from the force and position information.
BRIEF DESCRIPTION OF THE DRAWINGS
• A more complete understanding of the present disclosure thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings wherein:
• FIG. 1 illustrates a schematic elevational diagram of a prior technology pump jack system having hardwired sucker rod load and position sensors, and connected to a well sucker rod string;
• FIG. 2 illustrates a schematic elevational diagram of a pump jack system having wireless sucker rod load and position sensors coupled to a well sucker rod string, a distance measuring device for determining well bore pipe elongation, and a wireless data input motor speed controller, according to a specific example embodiment of this disclosure;
• FIG. 3 illustrates a more detailed schematic block diagram of the wireless sensor packages shown inFIG. 2;
• FIG. 4 illustrates a schematic elevational diagram of a pump jack system having wireless sucker rod load and distance measurement sensors coupled to a well sucker rod string, a distance measuring device for determining well bore pipe elongation, and a wireless data input motor speed controller, according to another specific example embodiment of this disclosure;
• FIG. 5 illustrates a more detailed schematic block diagram of the wireless sensor packages shown inFIG. 4;
• FIG. 6 illustrates a schematic elevational diagram of a pump jack system having wireless sucker rod load measurement sensors coupled to a well sucker rod string, distance measuring devices for determining well sucker rod string positions and well bore pipe elongation, and a wireless data input motor speed controller, according to still another specific example embodiment of this disclosure;
• FIG. 7 illustrates a more detailed schematic block diagram of the wireless sensor packages shown inFIG. 6; and
• FIG. 8 illustrates schematic diagrams of various power sources available for powering the wireless sensor packages shown inFIGS. 3,5 and7, according to specific example embodiments of this disclosure.
• While the present disclosure is susceptible to various modifications and alternative forms, specific example embodiments thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific example embodiments is not intended to limit the disclosure to the particular forms disclosed herein, but on the contrary, this disclosure is to cover all modifications and equivalents as defined by the appended claims.
DETAILED DESCRIPTION
• Referring now to the drawing, the details of specific example embodiments are schematically illustrated. Like elements in the drawings will be represented by like numbers, and similar elements will be represented by like numbers with a different lower case letter suffix.
• Referring toFIG. 2, depicted is a schematic elevational diagram of a pump jack system having wireless sucker rod load and position sensors coupled to a well sucker rod string, a distance measuring device for determining well bore pipe elongation, and a wireless motor speed controller, according to a specific example embodiment of this disclosure. The pump jack system, according to the teachings of this disclosure and generally represented by the numeral200, comprises asucker rod string110, apolish rod120, ahorsehead122, arocker beam124, connectingrod132,counter weight134.Pittman arm136, motor/gear drive138,frame128 andbase146. Awireless sensor package250 is mechanically and electrically attached to theload cell114, and moves therewith. In addition, anotherwireless sensor package254 attached at about the top of thewell bore pipe118, e.g., coupled to the flange/fluid takeoff assembly116. Thewireless sensor package254 comprises a distance measurement device that accurately measures a distance, d, from thewireless sensor package254 to areference point256, e.g., a target at ground level.
• As the motor/gear drive138 rotates, thePittman arm136 causes the connectingrod132 to push up or pull down one end of therocker beam124. On the other end of therocker beam124 is thehorsehead122 connected to thepolish rod120. As thehorsehead122 moves up and down so does thepolish rod120 which in turn moves thesucker rod string110 in and out of thewell bore pipe118. The well borepipe118 is terminated at the flange/fluid takeoff assembly116 that is adapted to allow fluid (or gas) being pumped out of thewell bore pipe118 to flow to a storage tank/pipeline (not shown). The flange/fluid takeoff assembly116 also is used to seal around a portion of thesucker rod string110 so that well fluid does not spill onto the ground. Pressure and flow rate sensors may also be incorporated into thewireless sensor package254. It is contemplated and within the scope of this disclosure that thesensor package254 may alternatively be hard wired to themotor speed controller258 since thesensor package254 is stationary with respect to thewell bore pipe118.
• Axial forces on thesucker rod string110 may be measured by aload cell114 that determines the axial forces applied to thesucker rod string110 when being draw upwards and when being pushed downward. Theload cell114 accomplishes these measurements by being held in a fixed position on thesucker rod string110 between atop clamp collar112aand abottom clamp collar112b. Theload cell114 may be, for example but is not limited to, a Lufkin Industries model 1923.
• Thewireless sensor package250 is mechanically and electrically coupled to theload cell114, and moves therewith. Aright angle coupling252 may be used for mounting thereof. Thewireless sensor package250 comprises an electrical interface for receiving electrical signals from theload cell114, and a position sensor, e.g., a tri-axial accelerometer (seeFIG. 3). Thewireless sensor package250 is adapted to transmit the sucker rod load and position information over a radio frequency channel(s), e.g., short-range radio, for example but not limited to, frequencies at about 315 MHz, 433 MHz, 868 MHz, 902 to 928 MHZ, 2.4 to 2.5 GHz, 5.7 to 5.8 GHz, etc. In addition, any form of transmission and modulation techniques may be used, for example but not limited to, spread spectrum to a compatible receive, e.g., spread spectrum receiver, coupled to amotor speed controller258. Computations for optimal motor speeds from the wireless load and position data may be performed in thewireless sensor package250 and/or the wirelessmotor speed controller258. A central controller receiving load and position information and/or motor speeds from each of the plurality of pump jacks may further be used to control pump speeds of the plurality of jump jacks so as to optimize oil field production, e.g., flow rates of pumped product. The central controller (not shown) may also determine optimal pumping parameters of each of the plurality of pump jacks so as to maximize oil field production.
• Once thesucker rod string110 axial forces and associated vertical positions thereof are available, a determination(s) can be made for a desired rotational speed(s) of the motor/gear drive138 to optimize well fluid pumping action. Note that the rotational speed can be varied during a pumping cycle (360 degree rotation of the Pittman arm136) to further optimize the well fluid pumping action.
• Referring toFIG. 3, depicted is a more detailed schematic block diagram of the wireless sensor packages shown inFIG. 2. Thewireless sensor package250 may comprise aposition sensor360, aposition sensor interface362, top and bottom load cell interfaces364, data processing logic andmemory storage368, awireless transmitter370a, and apower source366. Theposition sensor360 may be a tri-axial accelerometer, for example but not limited to, Analog Devices ADXL330.
• As thesucker rod string110 moves up and down, represented schematically by the heavy line double arrow, theposition sensor360 determines at the movement distances from a reference point. Thus real time position signals representative of the positions of thesucker rod string110 are available from theposition sensor360. Thepower source366 supplies power to theposition sensor360, the data processing logic andmemory storage368, and the wireless transmitter370. Theinterfaces362 and364 may receive power from the data processing logic andmemory storage368, and theload cells114 may receive power from their respective interfaces364.
• The top andbottom load cells114aand114balso make available real time signals representative of the up and down forces, respectively, being applied to thesucker rod string110. These real time position and force signals are transferred by the respectiveposition sensor interface362 and load cell interfaces364 to the data processing logic andmemory storage368. The data processing logic andmemory storage368 may comprise a digital processor (not shown) and a memory (not shown). The data processing logic andmemory storage368 may be used for processing the real time position and force signals into optimal motor speed control values to be transmitted to the wirelessmotor speed controller258 through the wireless transmitter370. Also values of the real time position and force signals may be stored in the memory of the data processing logic andmemory storage368 for historical and exception reporting, e.g., real time position and/or force values that are outside of the expected norm, and may be exception reported through the wireless transmitter370 to a control and monitoring system (not shown) or as a shutdown and/or alarm signal to the wirelessmotor speed controller258.
• Thesensor package254 may comprise adistance detector372, e.g., a distance determining device using, for example but not limited to, ultrasonic, radio frequency (radar), infrared or laser light timed pulse transmissions. Anotherwireless transmitter370bmay be used to transmit the distance information from thedistance detector372 and used for determining the elongation of thewell bore pipe118 due to an increase of the downhole temperature. In addition, pressure and/or flow rate sensors may be coupled at the flange/fluid takeoff assembly116. Thesensor package254 may be powered through an internal power source (e.g., wireless sensor package) or from the motor speed controller258 (hardwired).
• Referring toFIG. 4, depicted is a schematic elevational diagram of a pump jack system having wireless sucker rod load and distance measurement sensors coupled to a well sucker rod string, a distance measuring device for determining well bore pipe elongation, and a wireless motor, speed controller, according to another specific example embodiment of this disclosure. The pump jack system, according to the teachings of this disclosure and generally represented by the numeral400, comprises asucker rod string110, apolish rod120, ahorsehead122, arocker beam124, connectingrod132,counter weight134,Pittman arm136, motor/gear drive138,frame128 andbase146. Awireless sensor package450 is mechanically and electrically coupled to theload cell114, and moves therewith. In addition, anotherwireless sensor package254 may be attached at about the top of thewell bore pipe118, e.g., coupled to the flange/fluid takeoff assembly116. Thesensor package254 comprises a distance measurement device that accurately measures a distance, d₁, from thesensor package254 to areference point256a, e.g., a target at ground level. Thesensor package254 may be wireless or hard wired to themotor speed controller258.
• Axial forces on thesucker rod string110 may be measured by theload cell114 as more fully described hereinabove. Thewireless sensor package450 comprises an electrical interface for receiving electrical signals from theload cell114, and a distance measurement sensor, e.g., ultrasonic, radio frequency, infrared, laser light that measure a distance, d₂, representing the vertical distance of theload cell114 from thereference point256b, e.g., a target at ground level. Thewireless sensor package450 is adapted to transmit the sucker rod load and distance information over a radio frequency channel(s) as described more fully hereinabove.
• It is contemplated and within the scope of this disclosure that the distance measurement device that measures the distance (position) of theload cell114 may be located at thereference point256bat or about ground level. By locating this distance measurement device at a fixed location (reference point256b) it can now be either wireless or wired to themotor controller258. In addition, the movablewireless sensor package450 may be simplied as it need only transmitload cell114 information wirelessly, as more fully described herein. Also any intellegent electronics may now be located with the stationary (fixed) distance measurement device, and a very low power and simple (e.g., Bluetooth) wireless communications protocol may be utilized for the real time load cell data.
• Referring toFIG. 5, depicted is a more detailed schematic block diagram of the wireless sensor packages shown inFIG. 4. Thewireless sensor package450 may comprise adistance detector560, adistance detector interface562, top and bottom load cell interfaces364, data processing logic andmemory storage368, awireless transmitter370a, and apower source366. Thedistance detector560 may be similar to thedistance detector372 as more fully described hereinabove.
• As thesucker rod string110 moves up and down, represented schematically by the heavy line double arrow, thedistance detector560 determines the distances, d₂, from thereference point256b. Thus real time positions derived from the measured distances, d₂, are representative of the positions of thesucker rod string110. Thepower source366 supplies power to thedistance detector560, the data processing logic andmemory storage368, and thewireless transmitter370a. Theinterfaces362 and364 may receive power from the data processing logic andmemory storage368, and theload cells114 may receive power from their respective interfaces364.
• The top andbottom load cells114aand114balso make available real time signals representative of the up and down forces, respectively, being applied to thesucker rod string110. These real time position and force signals are transferred by the respectivedistance detector interface562 and load cell interfaces364 to the data processing logic andmemory storage368. The data processing logic andmemory storage368 may comprise a digital processor (no(shown) and a memory (not shown). The data processing logic andmemory storage368 may be used for processing the real time position and force signals into optimal motor speed control values to be transmitted to the wirelessmotor speed controller258 through thewireless transmitter370a. Also values of the real time position and force signals may be stored in the memory of the data processing logic andmemory storage368 for historical and exception reporting, e.g., real time position and/or force values that are outside of the expected norm, and may be exception reported through thewireless transmitter370ato a control and monitoring system (not shown) or as a shutdown and/or alarm signal to the wirelessmotor speed controller258.
• It is contemplated and within the scope of this disclosure that thedistance detector560, thedistance detector interface562 and the data processing andstorage368 may be located at the fixed location (reference point256b) and thewireless sensor package450 need only comprise the load cell interfaces364, apower source366aand awireless transmitter370a. The housing of thewireless sensor package450 could serve as a reflective target for thedistance detector560 or a distance measuring signal reflective plate can be attached thereto. See alsoFIG. 7 and the disclosure therefor hereinbelow.
• Thesensor package254 may comprise adistance detector372, e.g., a distance determining device using, for example but is not limited to, ultrasonic, radio frequency (radar), infrared or laser light timed pulse transmissions. Anotherwireless transmitter370bmay be used to transmit the distance information from thedistance detector372 and used for determining the elongation of thewell bore pipe118 due to an increase of the downhole temperature. In addition, pressure and/or flow rate sensors may be coupled at the flange/fluid takeoff assembly116.
• Referring toFIG. 6, depicted is a schematic elevational diagram of a pump jack system having wireless sucker rod load measurement sensors coupled to a well sucker rod string, distance measuring devices for determining well sucker rod string positions and well bore pipe elongation, and a wireless motor speed controller, according to still another specific example embodiment of this disclosure. The pump jack system, according to the teachings of this disclosure and generally represented by the numeral600, comprises asucker rod string110, apolish rod120, ahorsehead122, arocker beam124, connectingrod132,counter weight134,Pittman arm136, motor/gear drive138,frame128 andbase146. Awireless sensor package650 is mechanically and electrically attached to theload cell114, and moves therewith. In addition, anotherwireless sensor package654 attached at about the top of thewell bore pipe118, e.g., coupled to the flange/fluid takeoff assembly116. Thesensor package654 comprises distance measurement devices that accurately measure distance, d_b, from thesensor package654 to areference point256, e.g., a target at ground level, and distance, d_a, from thesensor package654 to the sensor package650 (also used as a target). Thesensor package654 may be wireless or hard wired to themotor speed controller258 since it remains stationary. The sum of the measured distances, d_aand d_b, plus the height of thesensor package654 will be representative of an accurate measured distance of theload cell114 from thereference point256. Both distances, d_aand d_b, have to be taken into account since elongation of thewell bore pipe118 vary depending upon the temperatures along thepipe118. An alternative mounting of a distance measurement sensor (not shown) at the fixedreference point256 may be used and then the distance from the ground mounted (or fixed pedistile mounted) distance detector in the sensor package654awould measure the housing as a target of thesensor package650. An advantage of putting the distance measurement detectors in the fixed sensor package652 is that only the load cell sensors in thesensor package650 need be wireless, though preferably allsensor packages650 and652 may be wireless.
• Axial forces on thesucker rod string110 may be measured by theload cell114 as more fully described hereinabove. Thewireless sensor package650 comprises an electrical interface for receiving electrical signals from theload cell114. Thewireless sensor package650 is adapted to transmit the sucker rod load over a radio frequency channel(s) as described more fully hereinabove.
• Referring toFIG. 7, depicted is a more detailed schematic block diagram of the wireless sensor packages shown inFIG. 6. Thewireless sensor package650 may comprise top and bottom load cell interfaces364, data processing logic andmemory storage368, awireless transmitter370a, and apower source366. It is contemplated and within the scope of this disclosure that the data processing andstorage368 may be located in the sensor package652 and that thewireless transmitter370amay communicate directly with a receiver (not shown) in the sensor package652. This will further reduce the power consumption used by thesensor package650. Thedistance detector760 may be similar to thedistance detector560 as more fully described hereinabove.
• As thesucker rod string110 moves up and down, represented schematically by the heavy line double arrow, thedistance detector760 determines the distance, d_a, from the top of thesensor package654 housing, and thedistance detector762 determines the distance, d_b, from the top of thewell bore pipe118 to the reference point256 (e.g., ground reference). Thus real time positions derived from the measured distances, d_aplus d_bplus the height of thesensor package654 housing, represent the positions of thesucker rod string110. Power sources supply power to thedistance detectors760 and762, the data processing logic andmemory storage368, and the wireless transmitters370. Theinterfaces362 and364 may receive power from the data processing logic andmemory storage368, and theload cells114 may receive power from their respective interfaces364. The data processing logic may also be located in thesensor package654 and that thesensor package654 may be either wireless or hard wired to themotor controller258. Also thewireless transmitter370amay send the load cell information first to a receiver (not shown) in thestationary sensor package654 where all of the smart processing may also be located.
• The top andbottom load cells114aand114balso make available real time signals representative of the up and down forces, respectively, being applied to thesucker rod string110. These real time position and force signals are transferred by the respectivedistance detector interface562 and load cell interfaces364 to the data processing logic andmemory storage368. The data processing logic andmemory storage368 may comprise a digital processor (not shown) and a memory (not shown). The data processing logic andmemory storage368 may be used for processing the real time position and force signals into optimal motor speed control values to be transmitted to the wirelessmotor speed controller258 through thewireless transmitter370a. Also values of the real time position and force signals may be stored in the memory of the data processing logic andmemory storage368 for historical and exception reporting, e.g., real time position and/or force values that are outside of the expected norm, and may be exception reported through thewireless transmitter370ato a control and monitoring system (not shown) or as a shutdown and/or alarm signal to the wirelessmotor speed controller258.
• Referring toFIG. 8, depicted are schematic diagrams of various power sources available for powering the wireless sensor packages shown inFIGS. 3,5 and7, according to specific example embodiments of this disclosure. Arechargeable battery366amay be used as thepower source366. Acapacitor366bmay be charged as described hereinafter and used as thepower source366. A battery andsolar cell charger366cmay be used as thepower source366. An inductive pick-upcharger coil480 external to thewireless sensor package250,450 or650 may be used to inductively charge theinternal charging coil482 coupled to thebattery478 throughrectifier484. A motion charger andbattery366cmay comprise a charging pick-up coil in close proximity to apermanent magnet488, wherein the permanent magnet moves in an axial direction depending upon the axial motion of thewireless sensor package250. Themagnet488 has mass and travels back and forth between the springs490 when thewireless sensor package250,450 or650 is moving up and down, thus charging thebattery478 through thediode484. Thebattery478 may be replaced with thecapacitor492 and be similarly charged. It is contemplated and within the scope of this disclosure that other sources ofpower366 not disclosed herein may be also be utilized to power the components of thewireless sensor package250.
• While embodiments of this disclosure have been depicted, described, and are defined by reference to example embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and are not exhaustive of the scope of the disclosure.

Claims (27)

1. A pump jack adapted for monitoring sucker rod load and position, comprising:

a sucker rod string in a well bore pipe;

a polished rod coupled to the sucker rod string;

a horsehead coupled to the polished rod;

a rocker beam coupled to the horsehead;

a connecting rod coupled to the rocker beam;

a counter weight coupled to the connecting rod;

a pittman arm coupled to the connecting rod and counter weight;

a variable speed motor-gear drive assembly coupled to the pittman arm for rotational movement thereof;

a frame pivotally coupled to the rocker beam;

a base attached to the frame;

first and second force sensors attached to a proximate end of the sucker rod string, wherein the first and second force sensors measure elongation and compression stresses, respectively, of the sucker rod string while the sucker rod string moves up and down in the well bore pipe;

a position sensor attached toward the proximate end of the sucker rod string, wherein the position sensor determines positions of the sucker rod string;

a sensor interface assembly having wireless transmitting capabilities, wherein the sensor interface assembly is attached to the sucker rod string, and is coupled to the first and second force measurement sensors and the position sensor, whereby the sucker rod string forces and position information are wirelessly transmitted therefrom; and

a wireless receiver coupled to the variable speed motor-gear drive assembly, wherein the wireless receiver receives the force and position information transmitted from the interface assembly for determining control of rotational speed of the variable speed motor-gear drive assembly.

2. The pump jack according toclaim 1, wherein the position sensor is a tri-axial accelerometer.

3. The pump jack according toclaim 1, wherein the position sensor is a distance measuring device for measuring distances between the proximate end of the sucker rod string and a reference point.

4. The pump jack according toclaim 3, wherein the distance measuring device uses ultrasonic pulses for measuring the distances.

5. The pump jack according toclaim 3, wherein the distance measuring device uses radio frequency pulses for measuring the distances.

6. The pump jack according toclaim 3, wherein the distance measuring device uses infrared pulses for measuring the distances.

7. The pump jack according toclaim 3, wherein the distance measuring device uses laser light pulses for measuring the distances.

8. The pump jack according toclaim 1, further comprising a well bore pipe elongation distance sensor coupled to a proximate end of the well bore pipe, and from which elongation length of the well bore pipe is available as elongation data.

9. The pump jack according toclaim 1, further comprising pressure and flow rate sensors coupled to a flange/fluid takeoff assembly that is coupled to the proximate end of the well bore pipe, and from which pressure and flow rate at the flange/fluid takeoff assembly are available as pressure and flow rate data, respectively.

10. An apparatus for monitoring position and load of a sucker rod in a pump jack, comprising:

first and second force sensors attached at a proximate end of a sucker rod string of a pump jack, wherein the first and second force sensors measure elongation and compression stresses, respectively, of the sucker rod string while the sucker rod string moves up and down in a well bore pipe;

a position sensor attached toward the proximate end the sucker rod string, wherein the position sensor determines positions of the sucker rod string; and

a sensor interface assembly having wireless transmitting capabilities, wherein the sensor interface assembly is attached to the sucker rod string, and is coupled to the first and second force measurement sensors and the position sensor, whereby the sucker rod string forces and position information are wirelessly transmitted therefrom.

11. The apparatus according toclaim 10, wherein the position sensor is a distance measuring device for measuring distances between the proximate end of the sucker rod string and a reference point.

12. The apparatus according toclaim 11, wherein the distance measuring device uses ultrasonic pulses for measuring the distances.

13. The apparatus according toclaim 11, wherein the distance measuring device uses radio frequency pulses for measuring the distances.

14. The apparatus according toclaim 11, wherein the distance measuring device uses infrared pulses for measuring the distances.

15. The apparatus according toclaim 11, wherein the distance measuring device uses laser light pulses for measuring the distances.

16. A pump jack adapted for monitoring sucker rod load and position, comprising:

a sucker rod string in a well bore pipe;

a polished rod coupled to the sucker rod string;

a horsehead coupled to the polished rod;

a rocker beam coupled to the horsehead;

a connecting rod coupled to the rocker beam;

a counter weight coupled to the connecting rod;

a pittman arm coupled to the connecting rod and counter weight;

a variable speed motor-gear drive assembly coupled to the pittman arm for rotational movement thereof;

a frame pivotally coupled to the rocker beam;

a base attached to the frame;

first and second force sensors attached to a proximate end of the sucker rod string, wherein the first and second force sensors measure elongation and compression stresses, respectively, of the sucker rod string while the sucker rod string moves up and down in the well bore pipe;

a sensor interface assembly having wireless transmitting capabilities, wherein the sensor interface assembly is attached to the sucker rod string, and is coupled to the first and second force measurement sensors, whereby the sucker rod string force information is wirelessly transmitted therefrom;

a distance measuring device attached on a plan of the base and under the sensor interface assembly, wherein the position sensor determines positions of the sucker rod string by measuring distances between the distance measuring device and the sensor interface assembly; and

a wireless receiver coupled to the variable speed motor-gear drive assembly, wherein the wireless receiver receives the force information transmitted from the sensor interface assembly, and wherein position information from the distance measuring device is coupled to the variable speed motor-gear drive assembly, whereby control of rotational speed of the variable speed motor-gear drive assembly is determined from the force and position information.

17. The pump jack according toclaim 16, wherein the distance measuring device uses ultrasonic pulses for measuring the distances.

18. The pump jack according toclaim 16, wherein the distance measuring device uses radio frequency pulses for measuring the distances.

19. The pump jack according toclaim 16, wherein the distance measuring device uses infrared pulses for measuring the distances.

20. The pump jack according toclaim 16, wherein the distance measuring device uses laser light pulses for measuring the distances.

21. The pump jack according toclaim 16, further comprising a well bore pipe elongation distance sensor coupled to a proximate end of the well bore pipe, and from which elongation length of the well bore pipe is available as elongation data.

22. The pump jack according toclaim 16, further comprising pressure and flow rate sensors coupled to a flange/fluid takeoff assembly that is coupled to the proximate end of the well bore pipe, and from which pressure and flow rate at the flange/fluid takeoff assembly are available as pressure and flow rate data, respectively.

23. An apparatus for monitoring position and load of a sucker rod in a pump jack, comprising:

first and second force sensors attached at a proximate end of a sucker rod string of a pump jack, wherein the first and second force sensors measure elongation and compression stresses, respectively, of the sucker rod string while the sucker rod string moves up and down in a well bore pipe;

a sensor interface assembly having wireless transmitting capabilities, wherein the sensor interface assembly is attached to the sucker rod string, and is coupled to the first and second force measurement sensors, whereby the sucker rod string force information is wirelessly transmitted therefrom;

a distance measuring device attached on a plane of a base of the pump jack and under the sensor interface assembly, wherein the distance measuring device determines positions of the sucker rod string by measuring distances between the distance measuring device and the sensor interface assembly; and

a wireless receiver coupled to the variable speed motor-gear drive assembly, wherein the wireless receiver receives the force information transmitted from the sensor interface assembly, and wherein position information from the distance measuring device is coupled to the variable speed motor-gear drive assembly, whereby control of rotational speed of the variable speed motor-gear drive assembly is determined from the force and position information.

24. The apparatus according toclaim 23, wherein the distance measuring device uses ultrasonic pulses for measuring the distances.

25. The apparatus according toclaim 23, wherein the distance measuring device uses radio frequency pulses for measuring the distances.

26. The apparatus according toclaim 23, wherein the distance measuring device uses infrared pulses for measuring the distances.

27. The apparatus according toclaim 23, wherein the distance measuring device uses laser light pulses for measuring the distances.

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