Patent Application
20240125316
The invention relates to 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.
In addition, the invention relates to 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.
The invention further relates to a computer-implemented method for determining operating properties of a drill-rod borehole pump.
Borehole pumps are used as delivery means to extract liquids stored underground when the reservoir pressure is not sufficient for them to reach the surface on their own or in sufficient quantities. In most cases, they are used to extract crude oil. Other fields of application include the pumping of brine and medicinal waters.
The image of most oil fields is dominated by drill-rod borehole pumps, which are also called horse-head pumps, nodding donkeys or donkey pumps because of their appearance and movement. Here, the actual pumping mechanism—a piston with check valves—is arranged in a separate pipe string in the borehole near the oil-bearing layer. The piston is set into a continuous up-and-down motion by means of a screwable rod from a pump jack located at the earth's surface. This is accomplished by the so-called horse head. This consists of a circular arc segment arranged as a balancer, at the end of which a steel cable pair or chain pair is clamped at the top.
The drive is mostly electric. However, in the presence of sufficient energy-containing gases dissolved in the crude oil, part of these gases can be separated from the pumped material on site by means of a degasser and fed to a gas engine that drives the pump.
Depending on the pump design and size, the working stroke is 1 to 5 m. Two and a half to twelve strokes per minute are common. The drill-rod borehole pump can be used economically up to pumping depths of around 2500 m. For greater depths, other pump systems are more suitable due to the large weight of the liquid column to be lifted.
The “Mark II” pump type from the Texan manufacturer Lufkin Industries is particularly suitable for high delivery rates from great depths due to its special movement geometry.
The “Sucker Rod” pump type has a sucker rod, which is a steel rod typically between 25 and 30 feet long and threaded at both ends, used in the oil industry to connect the surface and borehole components of a reciprocating pump installed in an oil well.
An extremely valuable tool for analyzing borehole performance is a borehole test rig, which measures the load on the polished rod in relation to the position of the polished rod.
Dynamometers can be used to record rod position and rod load over time. The load-measuring part of the dynamometer is attached to the polished rod so that the load can be measured and sent to a recorder. An accompanying part of the dynamometer attached to the lifting beam measures the position of the polished rod and sends it to the same recorder. The graph produced is called a dynagraph, or more commonly a dynamometer or dynagraph map, and corresponds to a load-displacement graph.
Dynamometer maps taken at the surface can rarely be used directly to measure the operating conditions of the borehole pump, since they also reflect all forces (static and dynamic) that occur from the pump to the borehole head. However, if a dynamometer is located directly above the pump, the recorded map is a true indicator of pump operation. Gilbert's dynagraph (a mechanical dynamometer) accomplished this in the 1930s. Rod loads directly above the pump, recorded as a function of pump position, give dynagraph maps a name that distinguishes them from surface maps. Although the use of Gilbert's dynagraph allowed direct investigation of pumping problems, the practical implications associated with the need to run the instrument in the borehole far outweighed its advantages.
Up to now, sensors have been used to measure the operating conditions of a drill-rod borehole pump, and these sensors measure the acting forces or the current position (inclination) of the beam (also known as the crank arm), for example by means of force sensors, Hall sensors or proximity sensors. From this, the position of the drill rod is calculated. However, it is time-consuming to calibrate the various sensors with each other. In addition, inaccurate calibration can lead to errors that may have an unfavorable influence on the evaluation of the measurement data.
It is an object of the invention to provide a method and a device for determining the operating properties of a drill-rod borehole pump, which simplifies the measurement of the operating conditions, whilst at the same time the measurement data are measured more accurately than is known in the prior art.
An object according to the invention is achieved by a method of the kind mentioned at the outset, wherein a measuring means is further provided for measuring the power consumption of the motor during operation of same, said method comprising the steps of: a) measuring the current consumption and the operating voltage of the motor in the form of discrete measuring points 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 of the motor therefrom, 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 the 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 delivery 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).
The invention recognizes that the operating properties of the delivery pump can also be ascertained without considering the motor speed. The invention is based here on the surprising realization that the operating properties of the delivery pump can also be ascertained by the torque curve, the period and the reference phase angle.
This means that no further sensors, which have to be attached to the pump, are required to determine the operating properties of the delivery pump.
Furthermore, a complex calibration of such sensors among each other can be spared.
The invention makes it possible to determine the operating properties of delivery pumps much more easily, flexibly and robustly. In addition, the accuracy in determining the operating properties of the delivery pump can be increased.
The discrete measuring points of the current consumption of the motor are measured with a sufficiently high sampling frequency.
The operating voltage supply of the motor can have one or more phases.
In a further development of the invention, it is provided that the period is ascertained with the aid of an approximated polynomial by the power values of the measuring points.
This enables precise determination of the operating properties of the delivery pump in a simple manner.
In a further development of the invention, it is provided that the period is ascertained with the aid of a polynomial 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.
This enables precise determination of the operating properties of the delivery pump in a simple manner.
In a further development of the invention, it is provided that a reference value is ascertained for the measuring points, at which a maximum is present for the change of the particular power value between two directly successive measuring points, and the period is determined with the aid of the reference value.
This enables precise determination of the operating properties of the delivery pump in a simple manner.
In a further development of the invention, it is provided that the operating properties of the delivery pump are determined with the aid of a load-displacement graph 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).
This enables precise determination of the operating properties of the delivery pump in a simple manner.
In a further development of the invention, it is provided that the reference phase angle is determined with respect to the absolute maximum of the power values of the measuring points within a pump cycle.
This enables precise determination of the operating properties of the delivery pump in a simple manner.
An object according to the invention is also solved by a pump system of the aforementioned type, wherein furthermore a measuring means is provided, which is designed to measure the power consumption of the motor during its operation, and furthermore a computing device with a memory is provided, which is designed to carry out the method according to the invention with the aid of the measuring means.
A further object of the invention to describe a computer-implemented method. This object of the invention directed to a computer-implemented method is solved by the features as claimed.
The invention is explained in more detail below with reference to an exemplary embodiment shown in the accompanying drawings. In the drawings:
The pump system 100 comprises a pump head 110 which is connected to a kinematics converter 120 via a drill rod 5, 10.
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.
Adjacently to the borehole head 6 is a casing 8, in which there runs a tube 9, guiding the drill rod 5 or 10.
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.
The casing 8 is formed in a borehole 13.
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.
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.
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.
The kinematics converter 120 converts a rotary motion of the motor 3 into a linear motion of the drill rod 5, 10.
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.
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.
The measured current and operating voltage values can be used to determine the effective power consumption and the apparent power consumption.
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.
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.
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.
The rod string or drill rod 10 is driven as shown in
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.
A receiving tube 19 is connected via a wing nut 20 to a piston assembly 21, which is located in a pump liner 22.
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.
The power values can be determined by the product of the discrete current values and the operating voltage.
The period 85 can be ascertained, for example, using an approximated polynomial 80 by the power values of the measuring points.
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.
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.
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).
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.
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.
The lowest point of the pump stroke 33 and the highest point of the pump stroke 34 can be seen.
Furthermore, a tip of the polished rod 35 (PPRI) is shown.
A map 36 of the polished rod for a pump speed equal to zero is shown by dashed lines.
Further, a map 37 of the polished rod for a pumping speed greater than zero is shown.
A minimum load of the polished rod 38 (MPRL) is shown.
A gross piston load 39 can also be read.
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.
In
A load-displacement graph 51 shows operation at full pump capacity.
A load-displacement graph 52 shows operation when the pumped medium is empty.
A corresponding setpoint 53 can be recognized.
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.
Further, load-displacement graphs 57 are shown with bar load with the particular mechanical work of the bars.
Graph 60 shows load-displacement graphs during normal operation.
Graph 61 shows load-displacement graphs for a fluid bearing.
Graph 62 shows load-displacement graphs under gas action in the underground store.
Graph 63 shows a load-displacement graph in the event that a piston is stuck.
Graph 64 shows a load-displacement graph in the event of leakage through a stationary valve.
Graph 65 shows a load-displacement graph in the event of leakage through a moving valve.
The display has a time axis 70 and an axis 71 for amplitude of current or power consumption.
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.
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.
Furthermore, a period 85 of the averaged power consumption can be determined for the polynomial 80.
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19206209.9 | Oct 2019 | EP | regional |
This application is the US National Stage of International Application No. PCT/EP2020/080274 filed 28 Oct. 2020, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP19206209 filed 30 Oct. 2019. All of the applications are incorporated by reference herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/080274 | 10/28/2020 | WO |
