WO2014168817A1 - Système de contrôle de course partielle pour puits de pétrole, puits de pétrole utilisant le système, et procédé - Google Patents

Système de contrôle de course partielle pour puits de pétrole, puits de pétrole utilisant le système, et procédé Download PDF

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Publication number
WO2014168817A1
WO2014168817A1 PCT/US2014/032877 US2014032877W WO2014168817A1 WO 2014168817 A1 WO2014168817 A1 WO 2014168817A1 US 2014032877 W US2014032877 W US 2014032877W WO 2014168817 A1 WO2014168817 A1 WO 2014168817A1
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WO
WIPO (PCT)
Prior art keywords
rod
tension
setpoint
downstroke
signal
Prior art date
Application number
PCT/US2014/032877
Other languages
English (en)
Inventor
Craig Lamascus
Lloyd Wentworth
Original Assignee
Integrated Control Systems, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Integrated Control Systems, Inc. filed Critical Integrated Control Systems, Inc.
Publication of WO2014168817A1 publication Critical patent/WO2014168817A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B47/00—Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps
    • F04B47/02—Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps the driving mechanisms being situated at ground level
    • F04B47/026—Pull rods, full rod component parts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/12—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by varying the length of stroke of the working members

Definitions

  • oil well include natural gas wells, and oil and gas wells including those that produce water or other fluids.
  • BACKGROUND Pumping units and rods used on oil wells typically have a fixed stroke length measured in inches of surface travel up and down.
  • the surface stroke length of the pumping unit is a function of the geometry and mechanical configuration of the pumping unit.
  • the surface stroke length of the rod under normal operating conditions, is identical to that of the pumping unit.
  • the rod which is operably connected to the pumping unit, makes one complete upstroke and downstroke in unison with the pumping unit.
  • Such a condition is called “float” or “rod float” wherein the rod and the pumping unit become mechanically disconnected.
  • the mechanical design of a pumping unit uses a prime-mover, usually in the form of an AC motor, turning in one direction.
  • the AC motor is connected to a series of power transmission devices that are comprised of belts, pulleys, sprockets, gear-boxes and/or drive chains.
  • the mechanical design of the pumping unit reverses the direction of rod motion from up to down at the top of the rod stroke and from down to up at the bottom of the rod stroke. Under normal conditions the direction of the motor rotation does not change while in operation. Under normal conditions, as the crank or drive chain of the pumping unit moves through a single revolution, the rod is operably connected to the pumping unit to make one complete up and downstroke in unison with the pumping unit.
  • Our partial stroke control method uses bi-directional motion of the crank or drive chain to cause the rod to move only through some portion of its normal surface stroke. This is useful because partial stroke of the rod and resulting partial stroke of the pump may be useful in eliminating or mitigating the cause of the problem that is causing the low-tension condition.
  • the prior art pumping system only reverse the direction of the movement of the rod through mechanical means, not by reversing the rotational direction of the electric motor driving the pumping system as we do.
  • a "walking beam” pump the connection between the rod and the pumping unit is done with a carrier bar and a bridle assembly connected to a horsehead.
  • the bridle is made of cable.
  • the carrier bar and bridle configuration allows the pumping unit to exert force to pull the rod up or prevent it from falling.
  • a rod clamp does not allow the rod to fall past the point at which the rod clamp engages the carrier bar.
  • This typical configuration does not allow the pumping unit to exert force to push the rod down.
  • rod float occurs in the event that the pumping unit moves down at a faster rate than the rod falls into the well, then rod float occurs. When rod float occurs, tension in the rod dramatically decreases and the bridle assembly goes into a "slack" condition.
  • the carrier bar can move down on the rod.
  • the connection between the rod and the pumping unit can vary depending on the type of pumping unit being used.
  • ROTAFLEX® pumping units use a belt instead of a horsehead.
  • the bridle consists of metal bars.
  • the carrier bar and bridle configuration allow the pumping unit to exert force to pull the rod up or prevent it from falling.
  • the rod clamp does not allow the rod to fall past the point at which the rod clamp engages the carrier bar.
  • the typical configuration does not allow the pumping unit to exert force to push the rod down. In the event that the pumping unit moves down at a faster rate than the rod falls into the well, then rod float occurs.
  • our system prevents a rod of a pumping unit for an oil well from completing a downstroke upon detecting a condition indicating that rod float is about to begin, specifically a decrease in tension.
  • Our system includes an AC electric motor that operates in a one direction to drive the rod through an upstroke and the downstroke, a sensor that detects tension in the rod on the downstroke of the rod and provides a measured tension signal corresponding to the tension, and a control circuit.
  • the control circuit is responsive to the measured tension signal to reverse the motor's forward direction whenever the tension signal is below a predetermined low-tension setpoint.
  • the circuit includes a microprocessor that receives from the sensor the measured tension signal and compares the measured tension signal to the predetermined low-tension setpoint.
  • the microprocessor generates a change direction command signal upon determining that the measured tension signal is below the low-tension setpoint to reverse the motor's direction, preventing the rod from completing the stroke cycle.
  • the change direction command signal is always generated on the downstroke, causing the rod to begin moving in an upward direction increasing tension in the rod.
  • the reversal of direction of the motor continues with each downstroke as long as a change direction command signal is generated on the downstroke, resulting in a series of repeated interruptions of the complete stroke cycle.
  • Our oil well employs our system and is operated according to our methods which include: (i) A method of operating an oil well comprising the steps of
  • Figure 1 A is an illustration comparing a pumping unit rod's position without rod float and with rod float.
  • Figure 1 is a schematic diagram of a pumping unit for an oil well that uses our control system depicted in Figure 2.
  • Figure 2 is a schematic diagram of our control system for an oil well.
  • Figure 3 is a schematic illustration of an oil well employing a walking beam pumping unit assembly using our system.
  • Figure 3A is a fragmentary view of a portion of the walking beam pumping unit assembly showing a rod with a load cell used to sense tension in the rod mounted on the rod.
  • Figure 3B is a cross-sectional view taken along line 3B-3B in Figure 3A.
  • FIG. 4 is a schematic illustration of an oil well employing a ROTAFLEX® pumping unit assembly using our system.
  • Figure 4A is a fragmentary view of a portion of the ROTAFLEX® pumping unit assembly showing the location of its rod with a load cell used to sense tension in the rod mounted on the rod.
  • DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS General Our system and method of operating an oil well prevents rod float. It achieves this by monitoring tension in the rod. Upon encountering a condition that will cause rod float tension in the rod decrease. By detecting a decrease in rod tension, and reversing the direction of the pumping unit's motor to change direction of the pumping unit from down to up at some point during its downward motion, rod float is avoided.
  • the Change Direction Command condition may occur during a normal run at high speed.
  • the Change Direction Command condition may only happen during a single isolated stroke, or it may persist for thousands of strokes over a period of several days.
  • the Change Direction Command condition may be intermittent or continuous.
  • the Change Direction Command condition may occur at the same location in the downstroke or different locations in the downstroke.
  • our control system 10a may employ a preferred forward direction. For such units, if the Change Direction Command condition results in “reverse” operation for a single stroke in which the Change Direction Command does not repeat, then the direction of the motor M and subsequent direction of the crank or drive chain is reversed to result in “forward" operation of the pumping unit PU.
  • Our control system 10a may be used in conjunction with a Minimum Load Shut Down function.
  • the Minimum Load Shut Down function works in such a way that the pumping unit PU is completely disabled in the event the measured rod tension drops below a threshold.
  • the Minimum Load Shut Down threshold is called "Min Tension Setpoint”. If the measured rod tension drops below the Min Tension Setpoint, the pumping unit PU is disabled and must be reset.
  • Our control system 10a allows pumping units installed on oil wells to be operated under conditions that would normally result in shutdown of the pumping unit PU and loss of production from the well, at least temporarily.
  • the number of events in a given period of time that causes the Change Direction Command to be activated can be broadly considered to be an indicator of "pump obstruction.”
  • a large number of Change Direction Command conditions in a given period of time indicates more severe pump obstruction.
  • a small, or zero, number of Change Direction Command conditions in a given period of time indicates a less or no pump obstruction.
  • Monitoring the number of pump obstructions is a useful measure of pump and well condition. A large number of pump obstructions may indicate a need for pump servicing.
  • Our control system 10a may be activated or de-activated, by means of a software switch, at the discretion of the operator.
  • the microprocessor 10a is programmed using the following variables: Reversal Setpoint Min, Reverse Enabled, Reverse Complete, Partial Counter, Reverse Command, Min Speed 2001, Speed Estimated 102, Filt Tension Scaled, Reversal Time Array, Reversal Time Array Counter and Return Forward.
  • the variables are described as follows -
  • Reversal Setpoint Min is a number that represents the minimum tension threshold that triggers a reversal of the drive mechanism.
  • Reverse Enabled is the name of a variable that contains a toggle and is either TRUE or FALSE depending on the control logic described below.
  • Reverse Complete is the name of a variable that contains a toggle and is either TRUE or FALSE depending on the control logic described below.
  • Partial Counter is the name of a variable that contains an integer that used in the implementation of the control.
  • Reverse Command is the name of a variable that contains a toggle and is either TRUE or FALSE depending on the control logic described below.
  • Min Speed is the name of a variable that contains an integer that represents the setting of the minimum motor speed in units of RPM.
  • Speed Estimated is the name of a variable that contains an integer that represents the estimated motor speed in units of RPM.
  • Filt Tension Scaled is the name of a variable that contains a real number that represents the filtered and measured tension from the load cell.
  • Return Forward is the name of a variable that contains a toggle and is either TRUE or FALSE depending on the control logic described below.
  • Reverse Enabled and Reverse Complete are both set to TRUE at the beginning of the control operation.
  • the Filt Tension Scaled is compared to the Reversal Setpoint Min and whenever the Filt Tension Scaled drops below the Reversal Setpoint Min and Reverse Enabled is set to TRUE then Reverse Enabled is set to FALSE and Reverse Complete is set to FALSE and the Partial Counter variable is incremented up by a value of 1.
  • Partial Counter is represented internally as an integer. If bit 0 of the Partial Counter integer is high then Reverse Command is set to TRUE and if Min Speed 2001 is not already a negative number it is set to a negative number.
  • Reverse Enabled is set to TRUE. If Reverse Command is FALSE and Speed Estimated 102 is greater than Min Speed 2001 times 0.9 and Filt Tension Scaled is greater than Reversal Setpoint Min times 1.1 then Reverse Enabled is set to TRUE as well.
  • Reverse Command is FALSE and Speed Estimated 102 bit 15 is FALSE (only happens when motor speed is positive, indicating forward rotation) then Reverse Complete is set to TRUE. If Reverse Command is TRUE or " Speed Estimated 102 bit 15 is TRUE (only happens when motor speed is negative, indicating reverse rotation) then Reverse Complete is set to FALSE. If Reverse Command is TRUE and the End of Stroke signal is detected then the Partial Counter is incremented by 1, thereby returning the pumping unit to the preferred "forward" direction of operation of the drive mechanism. In all cases in which our method is useful the Reverse Command will occur on the downward stroke of the rod and the pumping unit.
  • Partial Stroke Control When Partial Stroke Control is active and the Reverse Command variable goes from FALSE to TRUE, the change in direction of the pumping unit and rod from moving down to moving up at some location in the downstroke results in a partial stroke, or a stroke that is only a portion of the normal surface stroke. If the Reverse Command variable makes any subsequent transitions from FALSE to TRUE then the Partial Stroke Control will continue to partial stroke the well as long as the Reverse Command continues to transition from FALSE to TRUE.
  • the Reverse Command may transition from FALSE to TRUE only on starting.
  • the Reverse Command may transition from FALSE to TRUE during a normal running condition at high speed.
  • the Reverse Command may transition from FALSE to TRUE during single isolated stroke or it may persist for thousands of strokes over a period of several days. There will be no damage to the pumping unit if this condition does persist.
  • the Reverse Command transition from FALSE to TRUE may be intermittent or continuous.
  • the Reverse Command transition from FALSE to TRUE may occur at the same location in the downstroke or different locations in the downstroke.
  • Our method defines a preferred forward direction. If the Change Direction Command condition results in "reverse" operation for a single stroke in which the Change Direction Command does not repeat, then the direction of the motor and subsequent direction of the crank or drive chain is reversed to result in "forward" operation of the pumping unit, as is explained above.
  • the Minimum Load Shut Down function works in such a way that the pumping unit is completely disabled in the event the measured rod tension drops below a threshold.
  • the Minimum Load Shut Down threshold is called "Min Tension Setpoint”. If the measured rod tension drops below the Min Tension Setpoint, the pumping unit is disabled and must be reset. In most pumping units operation at extremely low or zero measured rod tension will result in mechanical damage to the pumping unit or rod.
  • the Partial Stroke Reversal Setpoint Min and "Min Tension Setpoint” are related as follows:
  • the Reversal Setpoint Min must be set to a value higher than the "Min Tension Setpoint” if the Partial Stroke Control is be to effective in maintaining the pumping unit in an operating condition and preventing shutdown or mechanical damage to the pumping unit and/or rod.
  • the number of events in a given period of time that cause the Reverse Command to make a transition from FALSE to TRUE can be broadly considered to be an indicator of "pump obstruction".
  • the number of pump obstructions that occur in a given amount of time is called the Reversal Time Array Counter.
  • the Reversal Time Array Counter is a variable that contains an integer that represents the number of pump obstruction events in the previous 24 hour period. A large value of the Reversal Time Array Counter indicates more severe pump obstruction. A small, or zero, value of the Reversal Time Array Counter indicates a less or no pump obstruction.
  • This control routine goes through the entire Reversal Time Array by setting Index_3 to a value of 498 and then decrementing it by a value of 1 until it reaches a value of 0.
  • the array element of Reversal Time Array location Index_3 plus 1 is given the value located in the array element of Reversal Time Array location Index_3. This has the effect of shifting all of the array elements backwards in the Reversal Time Array by one location at each occurrence of a Reverse Command event. Then the Reversal Time Array at location 0 is given the value of the present time. Every 60 seconds another control routine is activated that counts the number elements in the Reversal Time Array that are not equal to zero.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)

Abstract

L'invention concerne un puits de pétrole, qui est conçu pour empêcher une tige d'une unité de pompage du puits de réaliser un cycle de course complet à chaque fois qu'une condition indiquant qu'un flotteur de tige est sur le point de commencer existe. La tension dans la tige est mesurée et comparée à un point de consigne à basse tension prédéterminé pour déterminer si le signal de tension mesuré est ou non inférieur au point de consigne à basse tension. Sur la course descendante, la direction de rotation du moteur est inversée lorsque le signal de tension mesuré est inférieur au point de consigne à basse tension. Par conséquent, la tige ne termine pas son cycle de course étant donné que la direction du mouvement de tige est changée de bas en haut. Le système est conçu pour interrompre le cycle de course à tout moment, lorsqu'une tension mesurée sur la course descendante est inférieure au point de consigne à basse de tension.
PCT/US2014/032877 2013-04-08 2014-04-03 Système de contrôle de course partielle pour puits de pétrole, puits de pétrole utilisant le système, et procédé WO2014168817A1 (fr)

Applications Claiming Priority (2)

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US201361809823P 2013-04-08 2013-04-08
US61/809,823 2013-04-08

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WO2014168817A1 true WO2014168817A1 (fr) 2014-10-16

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3938910A (en) * 1974-05-13 1976-02-17 Dresser Industries, Inc. Oil well pumpoff control system
US4490094A (en) * 1982-06-15 1984-12-25 Gibbs Sam G Method for monitoring an oil well pumping unit
US5018350A (en) * 1990-05-09 1991-05-28 Bender E A Long stroke deep well pumping unit
US5251696A (en) * 1992-04-06 1993-10-12 Boone James R Method and apparatus for variable speed control of oil well pumping units
US20020007952A1 (en) * 2000-07-24 2002-01-24 Vann Roy R. Cable actuated downhole smart pump
US20060067834A1 (en) * 2004-09-17 2006-03-30 Boyer Lemoyne Method for mitigating rod float in rod pumped wells
US20120205119A1 (en) * 2009-10-26 2012-08-16 Harold Wells Associates, Inc. Pump control device, oil well with device and method

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3938910A (en) * 1974-05-13 1976-02-17 Dresser Industries, Inc. Oil well pumpoff control system
US4490094A (en) * 1982-06-15 1984-12-25 Gibbs Sam G Method for monitoring an oil well pumping unit
US5018350A (en) * 1990-05-09 1991-05-28 Bender E A Long stroke deep well pumping unit
US5251696A (en) * 1992-04-06 1993-10-12 Boone James R Method and apparatus for variable speed control of oil well pumping units
US20020007952A1 (en) * 2000-07-24 2002-01-24 Vann Roy R. Cable actuated downhole smart pump
US20060067834A1 (en) * 2004-09-17 2006-03-30 Boyer Lemoyne Method for mitigating rod float in rod pumped wells
US20120205119A1 (en) * 2009-10-26 2012-08-16 Harold Wells Associates, Inc. Pump control device, oil well with device and method

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