METHOD FOR DETERMINING OPERATING PROPERTIES OF A DRILL-ROD BOREHOLE PUMP, AND PUMP SYSTEM FOR SAME

Abstract

A method for determining operating properties of a drill-rod borehole pump, having a pump head, which is connected to a kinematics converter via a drill rod, and the kinematics converter is driven by an electric motor, and furthermore a measuring device is provided for measuring the power consumption of the motor during operation of same.

Claims

1. A method for determining operating properties of a drill-rod borehole pump, comprising a pump head, which is connected to a kinematics converter via a drill rod, and the kinematics converter is driven by an electric motor, and furthermore a measuring device is provided for measuring a power consumption of the motor during operation of same, the method comprising: a) measuring a current consumption and an operating voltage of the motor over at least one pump cycle, with which four operating phases of the borehole pump can be associated in each case, and determining the power consumption therefrom with power values, b) determining, for one pump cycle, a period and a maximum of the power consumption that corresponds to the torque maximum of the borehole pump, c) determining a reference phase angle for the kinematics converter with the aid of the properties of the kinematics converter and the power consumption of the motor, which reference phase angle describes a relationship between the maximum of the power consumption and the maximum of the force acting on the drill rod of the borehole pump, d) ascertaining a torque curve from the power consumption of the motor with the aid of the properties of the kinematics converter, e) determining the operating properties of the borehole pump from the torque curve ascertained in step d) using the period determined in step b) and the reference phase angle determined in step c).

2. The method as claimed in claim 1, wherein the period is ascertained with the aid of an approximated polynomial by the power values of the measuring points.

3. The method as claimed in claim 1, wherein the period is ascertained with the aid of a polynomial which takes into account statistical mean values of the power values of the respective measuring points over at least five pump cycles for interpolation points of the polynomial.

4. The method as claimed in claim 2, wherein a reference value is ascertained for the measuring points, at which reference value a maximum is present for a change in the particular power value between two directly successive measuring points, and the period is ascertained with the aid of the reference value.

5. The method as claimed in claim 1, wherein the operating properties of the borehole pump are determined with the aid of a load-displacement graph, which is determined from the torque curve determined in step d) using the period determined in step b) and the reference phase angle ascertained in step c).

6. The method as claimed in claim 1, wherein the reference phase angle is determined with respect to the absolute maximum of the power values of the measuring points within a pump cycle.

7. A pump system with a drill-rod borehole pump, comprising: a pump head, which is connected to a kinematics converter via a drill rod, and the kinematics converter is driven by an electric motor, and a measuring device, which is adapted to measure a power consumption of the motor during operation of same, and a computing device with a memory which is designed to carry out the method as claimed in claim 1 with the aid of the measuring device.

8. A computer-implemented method for determining operating properties of a drill-rod borehole pump, comprising: implementing the method as claimed in claim 1 on a computer.

9. The method as claimed in claim 3, wherein the period is ascertained with the aid of a polynomial which takes into account statistical mean values of the power values of the respective measuring points over at least ten pump cycles for interpolation points of the polynomial.

10. The method as claimed in claim 3, wherein the period is ascertained with the aid of a polynomial which takes into account statistical mean values of the power values of the respective measuring points over at least fifty pump cycles for interpolation points of the polynomial.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention is explained in more detail below with reference to an exemplary embodiment shown in the accompanying drawings. In the drawings:

[0036] FIG. 1 shows an exemplary embodiment of a system according to the invention with a drill-rod borehole pump,

[0037] FIG. 2 shows an exemplary embodiment of a pump head of a drill-rod borehole pump,

[0038] FIG. 3 shows an exemplary embodiment of a flowchart of the method according to the invention,

[0039] FIG. 4 shows a first exemplary embodiment of a load-displacement graph,

[0040] FIG. 5 shows load-displacement graphs for a pump at different output levels,

[0041] FIG. 6 shows load-displacement graphs for a pump at different loads and in different operating modes,

[0042] FIG. 7 shows a time representation of a current curve of an electric drive motor for a drill-rod borehole pump.

DETAILED DESCRIPTION OF INVENTION

[0043] FIG. 1 shows an exemplary embodiment of a pump system 100 according to the invention with a drill-rod borehole pump 1 of the sucker-rod pump type.

[0044] The pump system 100 comprises a pump head 110 which is connected to a kinematics converter 120 via a drill rod 5, 10.

[0045] The drill rods 5, 10 form a so-called rod string and run through a borehole head 6, to which there is connected a flow line 7 for discharging a pumped medium 14.

[0046] Adjacently to the borehole head 6 is a casing 8, in which there runs a tube 9, guiding the drill rod 5 or 10.

[0047] Attached to the lower end of the drill rod 10 is the pump head 110, which includes a piston 11 in a barrel 12. A movement of the piston 11 causes the pumped medium 14 to be pumped out.

[0048] The casing 8 is formed in a borehole 13.

[0049] For example, the kinematics converter 120 is driven by a prime mover in the form of an electric motor 3 via a reduction gearing 4. The kinematics converter 120 may additionally comprise a hydraulic power booster.

[0050] In this example, the mechanical connection of the kinematics converter 120 is established via a running beam 2, but can vary depending on the type of pump used.

[0051] A person skilled in the art is familiar with such kinematics converters, as well as their description in the form of properties of a kinematics converter by the transformation function of mechanical movements and forces.

[0052] The kinematics converter 120 converts a rotary motion of the motor 3 into a linear motion of the drill rod 5, 10.

[0053] The properties of the kinematics converter 120 can be described, for example, in terms of leverage effects and transmission ratios, as well as in terms of electrical drive power and moving masses. It should be noted that the position of a flywheel mass along a rotational motion and the corresponding force applied to the drill rod 10 are related in time, which is referred to as a reference phase angle. For a particular pump arrangement, a reference phase angle can be determined using the kinematics principles of mechanics, as known to a person skilled in the art.

[0054] Furthermore, a measuring means 130 is provided, which is designed to measure the current consumption and the operating voltage of the individual phases of the motor 3 during its operation. This can be done, for example, by an ammeter or voltmeter which measures discrete measuring points with current or voltage values, in particular with high temporal resolution.

[0055] The measured current and operating voltage values can be used to determine the effective power consumption and the apparent power consumption.

[0056] Furthermore, a computing device 140 with a memory 150 is provided, which is designed to carry out the method according to the invention with the aid of the measuring means 130.

[0057] It is known to a person skilled in the art how a reference phase angle for the kinematics converter 120 can be ascertained using the properties of the kinematics converter 120 and the power consumption 72 of the motor 3, which describes the relationship between the maximum 82 of the power consumption 72 and the maximum of the force acting on the drill rod of the borehole pump 1.

[0058] It is also known to a person skilled in the art how a torque curve can be determined from the power consumption 72 of the motor 3 using the properties of the kinematics converter 120.

[0059] FIG. 2 shows another, more detailed example of a prior art pump head 111.

[0060] The rod string or drill rod 10 is driven as shown in FIG. 1 and is set into an up-and-down linear motion.

[0061] In the variant of the pump head 111 shown, there is arranged in the borehole 13 a cover tube 15 with vertical grooves, which guides inside the cover tube 15, via a holding device 16 and a self-aligning bearing 17, a rotating tube 18 with spiral grooves.

[0062] A receiving tube 19 is connected via a wing nut 20 to a piston assembly 21, which is located in a pump liner 22.

[0063] A calibrated rod 23 is connected to the drill rod 10 via a pin 24 and a holding device 25, which drives the piston assembly by way of the linear motion.

[0064] FIG. 3 shows an exemplary embodiment for a flowchart of the method according to the invention with the following steps: a) measuring the current consumption and the operating voltage of the motor 3 in the form of discrete measuring points with a sampling frequency over at least one pump cycle with which four operating phases of the borehole pump 1 can be associated in each case, and determining therefrom the power consumption 72 of the motor 3 with power values, b) determining, for one pump cycle, a period 85 and a maximum 82 of the power consumption 72 that corresponds to the torque maximum of the borehole pump 1, c) determining a reference phase angle for the kinematics converter 120 with the aid of the properties of the kinematics converter 120 and the power consumption of the motor 3, which reference phase angle describes the relationship between the maximum 82 of the power consumption and the maximum of the force acting on the drill rod of the borehole pump 1, d) ascertaining a torque curve from the power consumption of the motor 3 with the aid of the properties of the kinematics converter 120, e) determining the operating properties of the delivery pump 1 from the torque curve ascertained in step d) using the period determined in step b) and the reference phase angle determined in step c).

[0065] The power values can be determined by the product of the discrete current values and the operating voltage.

[0066] The period 85 can be ascertained, for example, using an approximated polynomial 80 by the power values of the measuring points.

[0067] However, the period 85 can also be determined, for example, with the aid of a polynomial 80 which takes into account statistical mean values of the power values of the various measuring points over at least five, advantageously at least ten, particularly advantageously at least fifty pump cycles for interpolation points of the polynomial.

[0068] A reference value 81 can be determined for the measuring points, at which reference value a maximum is present for the change of the particular power value between two directly successive measuring points, and the period 85 is ascertained with the aid of the reference value 81.

[0069] The operating properties of the delivery pump 1 can be determined with the aid of a load-displacement graph 30, 50, 54, 57, 60-65, which is determined from the torque curve ascertained in step d) using the period determined in step b) and the reference phase angle determined in step c).

[0070] The reference phase angle can be determined with respect to the absolute maximum of the power values of the measuring points within a pump cycle.

[0071] FIG. 4 to FIG. 6 show examples of load-displacement graphs which are often used to determine the operating properties of drill-rod borehole pumps.

[0072] FIG. 4 shows a load-displacement graph 30.

[0073] The position 31 of the polished bar is plotted on the x-axis, and the load 32 of the polished bar is plotted on the y-axis.

[0074] The lowest point of the pump stroke 33 and the highest point of the pump stroke 34 can be seen.

[0075] Furthermore, a tip of the polished rod 35 (PPRI) is shown.

[0076] A map 36 of the polished rod for a pump speed equal to zero is shown by dashed lines.

[0077] Further, a map 37 of the polished rod for a pumping speed greater than zero is shown.

[0078] A minimum load of the polished rod 38 (MPRL) is shown.

[0079] A gross piston load 39 can also be read.

[0080] In addition, a weight of the rods in the fluid 40 can be determined, as well as forces 41 and 42, and a pump stroke or pump displacement 43.

[0081] In FIG. 5, load-displacement graphs 50 are shown with bar load at setpoint as a function of load 32 of the polished bar across the particular position 31 of the polished bar.

[0082] A load-displacement graph 51 shows operation at full pump capacity.

[0083] A load-displacement graph 52 shows operation when the pumped medium is empty.

[0084] A corresponding setpoint 53 can be recognized.

[0085] Further, load-displacement graphs 54 are shown with bar load at a change of operation as a function of the load 32 of the polished bar across the particular position 31 of the polished bar, wherein respective angles 55, 56 can be read.

[0086] Further, load-displacement graphs 57 are shown with bar load with the particular mechanical work of the bars.

[0087] FIG. 6 shows load-displacement graphs 60-65 for various operating conditions.

[0088] Graph 60 shows load-displacement graphs during normal operation.

[0089] Graph 61 shows load-displacement graphs for a fluid bearing.

[0090] Graph 62 shows load-displacement graphs under gas action in the underground store.

[0091] Graph 63 shows a load-displacement graph in the event that a piston is stuck.

[0092] Graph 64 shows a load-displacement graph in the event of leakage through a stationary valve.

[0093] Graph 65 shows a load-displacement graph in the event of leakage through a moving valve.

[0094] FIG. 7 shows an example of a time display of a power curve of an electric drive motor for a drill-rod borehole pump, which was ascertained from the current consumption and operating voltage of the motor 3.

[0095] The display has a time axis 70 and an axis 71 for amplitude of current or power consumption.

[0096] A power consumption 72 is shown for which a zero point or zero axis 81, and a polynomial 80 for averaged power consumption can be determined.

[0097] For the polynomial 80, a maximum value 82 of the averaged power consumption, as well as zero crossings 83, 84 of the averaged power consumption can be ascertained.

[0098] Furthermore, a period 85 of the averaged power consumption can be determined for the polynomial 80.

[0099] From this, a phase angle 86 of the averaged power consumption can be ascertained, which describes the relationship between the rotary motion of the motor 3 and the drill rod 10 of the pump 1.

[0100] From the ascertained values, a corresponding load-displacement graph can be ascertained in order to easily derive the operating properties of the drill-rod borehole pump 1.

LIST OF REFERENCE SIGNS

[0101] 1 drill-rod borehole pump [0102] 2 running beam [0103] 3 prime mover, motor [0104] 4 reduction gearing [0105] polished rod [0106] 6 borehole head [0107] 7 flow line [0108] 8 casing [0109] 9 tube [0110] rod string [0111] 11 piston [0112] 12 barrel [0113] 13 borehole [0114] 14 pumped medium [0115] cover tube with vertical grooves [0116] 16, 25 holding device [0117] 17 self-aligning bearing [0118] 18 rotating rube with spiral grooves [0119] 19 receiving tube [0120] wing nut [0121] 21 piston assembly [0122] 22 pump liner [0123] 23 calibrated rod [0124] 24 pin [0125] 30 load-displacement graph [0126] 31 position of the polished rod [0127] 32 load of the polished rod [0128] 33 lowest point of the pump stroke [0129] 34 highest point of the pump stroke [0130] 35 tip of the polished rod, PPRI [0131] 36 map of the polished rod for pump speed equal to zero [0132] 37 map of the polished rod for pump speed greater than zero [0133] 38 minimum load of the polished rod, MPRL [0134] 39 gross piston load [0135] 40 weight of the rods in the fluid [0136] 41, 42 force [0137] 43 displacement [0138] 50 load-displacement graph with bar load at setpoint [0139] 51 pump, full power [0140] 52 pumped empty [0141] 53 setpoint [0142] 54 load-displacement graph with rod load with change of operation [0143] 55, 56 angle [0144] 57 load-displacement graph with mechanical work of the rods [0145] 60 load-displacement graph in normal operation [0146] 61 load-displacement graph with a fluid bearing [0147] 62 load-displacement graph under gas action [0148] 63 load-displacement graph in the event that a piston is stuck [0149] 64 load-displacement graph in the event of leakage through a stationary valve [0150] 65 load-displacement graph in the event of leakage through a moving valve [0151] 70 time axis [0152] 71 axis for amplitude of current or power consumption [0153] 72 power consumption [0154] 80 selected zero point or zero axis [0155] 81 polynomial for averaged power consumption [0156] 82 maximum value of the averaged power consumption [0157] 83, 84 zero crossing of the averaged power consumption [0158] 85 period of the averaged power consumption [0159] 86 ascertained phase angle of the averaged power consumption [0160] 100 pump system [0161] 110, 111 pump head [0162] 120 kinematics converter [0163] 130 measuring means [0164] 140 computing device [0165] 150 memory