Screw pump rotor structure optimization method and system based on wear trajectory quantization

Abstract

The invention belongs to the technical field of oil exploitation equipment, and particularly provides a screw pump rotor structure optimization method and system based on wear trajectory quantization, and the method comprises the steps: obtaining the contact conditions of the motion trajectory of feature points on the surface of a rotor and the inner wall of a stator in different angle intervals according to the motion trajectory of the surface of the rotor; calculating the geometric wear strength of each feature point according to the contact condition; and optimizing the rotor structure according to the geometric wear strength so as to homogenize the wear. From the perspective of structure optimization, the problem of uneven wear can be more effectively solved by quantifying the wear track and optimizing the rotor line type in a segmented manner.

Description

Technical Field

[0001] The present application relates to the technical field of oil production equipment, and in particular to a method and system for optimizing the rotor structure of a screw pump based on wear track quantification. Background Art

[0002] All-metal screw pumps are widely used in oil production, especially in deep-well operations. Their rotors are connected to the sucker rods (configured according to the well depth). These rods, which can stretch up to several thousand meters in length, are stretched tens of centimeters in length when placed vertically under their own gravity. Furthermore, changes in the physical state of the crude oil, particularly increases in viscosity or sand content, cause downward tension on the rods. If the rods are stretched by one thread per meter, a 2,000-3,000-meter rod will stretch by 2-3 cm. This creates significant resistance, and uneven wear caused by direct and indirect contact between the stator and rotor severely limits the pump's service life. Existing research has primarily focused on mitigating wear through material improvements or surface treatments, but with limited success. Summary of the Invention

[0003] The present application aims to solve the technical problem of uneven wear of screw pump rotors in the prior art, and proposes a method and system for optimizing the structure of screw pump rotors based on wear trajectory quantification.

[0004] In a first aspect, the present disclosure provides a method for optimizing the structure of a screw pump rotor based on wear track quantification, comprising: S1, according to the motion trajectory of the rotor surface, obtain the contact situation between the motion trajectory of the characteristic point on the rotor surface and the inner wall of the stator in different angle intervals; S2, calculating the geometric wear intensity of each characteristic point according to the contact condition; S3, optimizing the rotor structure according to the geometric wear intensity to make the wear uniform.

[0005] Preferably, the S1 specifically includes: S101, selecting multiple feature points on the rotor surface, establishing a conversion relationship between the rotor feature points in the moving coordinate system X1O1Y1 and the fixed coordinate system XOY, and establishing a motion trajectory equation; S102, using the motion trajectory equation, solve the contact conditions between the motion trajectory of the characteristic point on the rotor surface and the inner wall of the stator in different angle intervals.

[0006] Preferably, the conversion relationship in S101 is: ; in, θ is the rotation angle of the line connecting the rotor characteristic point and the moving coordinate system O1 to the moving coordinate system O1Y1 axis; Φis the rotation angle of the line connecting the origin O1 of the moving coordinate system and the origin O of the fixed coordinate system with respect to the OY axis of the fixed coordinate system; t is the rotor pitch; e is the eccentricity of the rotor.

[0007] Preferably, the S2 specifically includes calculating the wear stroke length of each feature point according to the contact situation. l , according to the wear stroke length l Calculation of geometric wear intensity k ; The wear stroke length l for: ; The geometric wear strength k for: ; in l 定 is the cross-sectional circumference of the stator inner wall; l 1. l 2 are the stator lengths of the two contact areas.

[0008] Preferably, the S3 specifically includes: The rotor surface is divided into three areas: high-intensity wear area, transition wear area, and gentle wear area; For high-intensity wear areas, reduce the rotor radius; For the transition wear zone, a transition curve is used to achieve a smooth transition of the radius; For the gentle wear area, the original radius of the rotor is kept unchanged.

[0009] Preferably, in the high-intensity wear zone, the calculation formula for the reduced rotor radius is as follows: ; in, ∆r The length that needs to be subtracted to optimize the rotor radius; k is the geometric wear strength; R is the radius of the unoptimized rotor; η is the adjustment coefficient.

[0010] Preferably, the optimized rotor radius changes with the characteristic point position angle α The expression of the change is as follows: ; in, ∆r The length to be subtracted to optimize the rotor radius is: θ 1 is the first angle value, θ 2 is the second angle value; the position angle of the feature point 0≤α≤ θ 2 is located in the high-intensity wear area; the position angle of the characteristic point θ2 ≤α≤θ 1 When it is in the transition wear zone; the position angle of the characteristic point θ When 1≤α≤180°, it is in the gentle wear zone.

[0011] Preferably, the screw pump rotor structure optimization method further includes: An optimized rotor axial linear equation is obtained according to the optimized rotor radius, and the rotor is processed according to the rotor axial linear equation.

[0012] Preferably, the optimized screw rotor axial linear equation is: ; When the rotor is of equal diameter, ; When the rotor is a conical rotor, ; in, D r1 is the diameter of the first end of the conical rotor, D r2 is the diameter of the second end of the conical rotor, L is the rotor length.

[0013] In a second aspect, the present invention further provides a screw pump rotor optimization system based on wear track quantification, which can be used to implement the above-mentioned screw pump rotor optimization method based on wear track quantification, and the system includes: The stator-rotor contact modeling module is used to obtain the contact conditions between the motion trajectory of the characteristic points on the rotor surface and the inner wall of the stator in different angle intervals according to the motion trajectory of the rotor surface; a wear calculation module, configured to calculate the geometric wear intensity of each feature point based on the contact conditions; The optimization module is used to optimize the surface structure of the rotor according to the geometric wear intensity to make the wear uniform.

[0014] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: This method uses a quantitative indicator of geometric wear intensity to scientifically assess the degree of wear in each rotor region, avoiding the blindness of empirical design. By optimizing the rotor radius in sections, the geometric wear intensity becomes more uniform, effectively alleviating the uneven wear problem of all-metal screw pump rotors. This method provides new insights and approaches for the structural optimization of all-metal screw pumps and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the stator and rotor structure of an all-metal screw pump provided in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the axial profile of the screw pump rotor provided in an embodiment of the present invention.

[0017] Figure 3 Schematic diagram of wear distribution of a screw pump provided in an embodiment of the present invention.

[0018] Figure 4 Schematic diagram of the rotor moving in the inner wall of the stator provided by an embodiment of the present invention.

[0019] Figure 5 This is a diagram analyzing the wear principle of the rotor characteristic point motion trajectory provided by an embodiment of the present invention.

[0020] Figure 6 A schematic diagram of the motion trajectory of the rotor symmetrical characteristic points provided by an embodiment of the present invention.

[0021] Figure 7 A schematic diagram of the motion trajectory of the rotor characteristic points provided by an embodiment of the present invention.

[0022] Figure 8 A schematic cross-sectional view of an all-metal conical screw pump provided in an embodiment of the present invention.

[0023] Figure 9 This is a scatter plot of geometric wear intensity provided by an embodiment of the present invention.

[0024] Figure 10 This is a radar diagram of the rotor geometric wear intensity provided by an embodiment of the present invention.

[0025] Figure 11 Schematic diagram of the uneven wear zone of a three-dimensional screw pump provided in an embodiment of the present invention.

[0026] Figure 12 Schematic diagram of the wear and fracture of a screw pump provided in an embodiment of the present invention.

[0027] Figure 13 A schematic diagram of the rotor optimization line provided by an embodiment of the present invention.

[0028] Figure 14 This is a scatter plot of geometric wear intensity provided by an embodiment of the present invention.

[0029] Figure 15 This is a geometric wear intensity radar chart provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0031] Unless otherwise defined, the technical or scientific terms used in this application should have the usual meanings understood by people with ordinary skills in the field to which this application belongs. The words "first", "second" and similar terms used in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "an" or "the" are not limited to quantity, but rather to the presence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used for relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0032] In each accompanying drawing, identical elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not all drawn to scale. In addition, some well-known parts may not be shown in the drawings.

[0033] Many specific details of the present application are described below, such as component structures, materials, dimensions, processing techniques, and technologies, to provide a clearer understanding of the present application. However, as will be appreciated by those skilled in the art, the present application may be implemented without following these specific details.

[0034] An embodiment of the present invention provides a method for optimizing the structure of a screw pump rotor based on wear track quantification, comprising: S1, according to the motion trajectory of the rotor surface, obtain the contact situation between the motion trajectory of the characteristic point on the rotor surface and the inner wall of the stator in different angle intervals; S2, calculating the geometric wear intensity of each characteristic point according to the contact condition; S4, optimizing the rotor structure according to the geometric wear intensity to make the wear uniform.

[0035] The following is a detailed description of the optimization process based on specific application scenarios: Step 1, such as Figures 1 to 2 , select rotor feature points on the all-metal screw pump rotor and establish the dynamic coordinate system X1O1Y1 and the fixed coordinate system XOY. Through coordinate transformation, the equation of the screw rotor surface is derived, and setting x = 0, the equation of the axial profile of the screw pump is obtained. The following relationship is obtained:

[0036] in, θThe angle of rotation of the line connecting point M (i.e., the rotor characteristic point) and the moving coordinate system O1 to the O1Y1 axis of the moving coordinate system, in degrees; Φ The angle of rotation of the line connecting the origin O1 of the moving coordinate system and the origin O of the fixed coordinate system with respect to the Y axis of the fixed coordinate system, in degrees; t is the screw pitch of the screw pump, in mm; e is the eccentricity of the screw, in mm.

[0037] Step 2, according to Figure 3 The uneven wear phenomenon obtained by the test is Figure 4 The motion simulation method is used to simulate the motion of the four quadrants of the rotor, and it is found that the four quadrants show uneven wear. Figure 5 (a) shows the coordinate system, where point p on the rotor corresponds to the 0° angle position and point p' corresponds to the α angle position. The motion trajectory of the rotor is drawn with point p' as the characteristic point. Figure 5 (b), where: (1) segments A'B' and C'D' are the range of wear between the rotor characteristic point p' and the stator inner wall, including direct contact wear and indirect contact wear; (2) within the wear range, the distance between the motion trajectory of the characteristic point p' and the stator inner wall is less than or equal to the maximum sand particle diameter.

[0038] Step 3: Based on the kinematic method, a feature point is selected every 10° along the 360-degree range of the rotor circumference (36 points in total), and its complete motion trajectory is drawn respectively. The positional relationship between the motion trajectory of the feature points at different positions of the rotor and the inner wall of the stator is analyzed, and the contact situation between the motion trajectory of the feature points on the rotor surface and the inner wall of the stator in different angle intervals is obtained to obtain the wear area situation.

[0039] Figure 6 The motion trajectories of three sets of symmetrically distributed feature points are selected, and their position angles α They are 30° and 330°, 70° and 290°, and 130° and 230°. The results show that the motion trajectories of feature points that are symmetrical along the Y axis are also symmetrical along the Y axis.

[0040] like Figure 7 (a), (b), and (c) show the distribution of the contact position between the feature point trajectory and the stator inner wall, as its position angle α The changes in show three significant intervals: (1) in the interval of 0°~80°, the motion trajectory of the feature point mainly contacts the arc segment of the stator inner wall; (2) in the interval of 80°~130°, the motion trajectory of the feature point contacts the stator inner wall in the transition area from the arc segment to the straight segment; in the interval of 130°~180°, the motion trajectory of the feature point mainly contacts the straight segment of the stator inner wall.

[0041] In step 4, a wear simulation test was performed using sand particles with a diameter of 0.15 mm.

[0042] In this embodiment, either a constant diameter rotor or a conical rotor can be selected. The conical rotor and the conical stator are matched to form a conical screw pump. Considering the longitudinal change of the cross-sectional diameter of the all-metal conical screw pump, the three-end cross-section of the conical screw pump is selected for simulation test. Figure 8 (a), (b), and (c) are schematic cross-sectional views of the large end, middle end, and small end, respectively. The large end rotor diameter is larger than the middle end rotor diameter, which is larger than the smallest end rotor diameter.

[0043] Step 5: Define the wear stroke length l and geometric wear strength k The formula is as follows: ; ; in, l 定 is the circumference of the stator inner wall cross section, in mm; l 1. l 2 are the stator lengths of segments A'B' and C'D', in mm.

[0044] The wear stroke length and geometric wear intensity data of the wear characteristic points at different angles were obtained through experimental calculation. The geometric wear intensity scatter plot is shown as follows: Figure 9 The wear intensity curve shows three different levels: 0°~80° is the high-intensity wear zone; 80°~130° is the transition wear zone; 130°~180° is the gentle wear zone.

[0045] The geometric wear intensity is plotted on the rotor surface to form a geometric wear intensity radar map, such as Figure 10 As shown. On the radar chart, the rotor is divided into three areas, namely yellow, blue and green areas, where the red point is the peak point of wear intensity: k The yellow area with >17.00% is the high-intensity wear area; the yellow area with <4.00% is the high-intensity wear area. k The blue area <17.00% is the transition wear area; 0.00%< k The green area with a wear rate of <4.00% is the gentle wear area.

[0046] Optionally, according to the structural characteristics of the screw pump, the two-dimensional plane uneven wear line of the wear feature point is restored to the three-dimensional model to form an uneven wear belt, such as Figure 11 As shown. And the width formula of the wear zone in the three-dimensional model is obtained: ; in, θ 2 is the second angle value, in degrees; t 1 is the width of the wear zone, in mm;t is the rotor pitch in mm.

[0047] Figure 12 The horizontal and vertical perspectives of the screw pump rotor that broke after running for one year under actual working conditions are shown. The distribution characteristics and width of the longitudinal wear zone are similar to those of the Figure 11 The fracture position is consistent with the high-intensity wear zone in the figure; the fracture position is consistent with the angle of the geometric wear intensity peak point, which is located at the position angle α =65°.

[0048] Step 6, based on Figure 10 The wear intensity distribution law of the rotor geometry is considered, and considering the operability in the actual rotor processing process, the rotor cross section is divided into three types of areas for optimization.

[0049] The first area (0°~80°): high-intensity wear area, by reducing the radius of the characteristic point, the distance between its motion trajectory and the inner wall of the stator and the wear stroke length are reduced, thereby achieving the purpose of reducing the geometric wear intensity. The uneven wear area is optimized in sections, where the high-intensity wear area: the reduced radius ; in, ∆r The length to be subtracted to optimize the rotor radius, in mm; R is the radius of the unoptimized rotor, in mm; η is the adjustment coefficient.

[0050] The second area (80°~130°) and the third area (130°~180°) are the transition wear area and the gentle wear area respectively. The wear intensity in the gentle wear area is relatively small and uniform, and the original rotor radius is retained. R ; The transition wear zone adopts a gentle curve adjustment ∆r The curvature difference caused by the optimized rotor is adjusted to balance the wear uniformity and structural continuity. α The expression of the change is as follows: ; in, r ( α ) is the optimized rotor radius, in mm; θ 1 is the first angle value, in degrees; θ 2 is the second angle value, in degrees.

[0051] In this embodiment, θ 1=130°, θ 2=80°.

[0052] Figure 13The optimized rotor radius is divided into three areas, namely the red area, the green area and the gray area. The radius of the red area (OGH) decreases, the radius of the gray area (OG'H') remains unchanged, and the green area (OGG', OH'H) is the radius of the transition curve after fitting. G and G' are respectively α =80°, 130°, H', H are α =230°, 280°. And get the optimized geometric wear intensity scatter plot and radar chart, such as Figure 14 、 Figure 15 .

[0053] Step 8: Obtain an optimized rotor axial linear equation according to the optimized rotor radius, and process the rotor according to the rotor axial linear equation.

[0054] Optional, optimized rotor axial line equation: ; When the rotor is of equal diameter, ; When the rotor is a conical rotor, ; in, D r1 is the diameter of the first end of the conical rotor, D r2 is the diameter of the second end of the conical rotor, L is the rotor length.

[0055] The present invention has the following advantages: 1. The present invention uses the geometric wear intensity quantitative index to scientifically evaluate the wear degree of each area of the rotor, avoiding the blindness of empirical design.

[0056] 2. The rotor radius is optimized in sections to make the geometric wear intensity uniform, effectively improving the uneven wear problem of the all-metal screw pump rotor.

[0057] 3. This method provides new ideas and methods for the structural optimization of all-metal screw pumps and has broad application prospects.

[0058] An embodiment of the present invention further provides a screw pump rotor structure optimization system based on wear track quantification, which can be used to implement the above-mentioned screw pump rotor structure optimization method based on wear track quantification. The system includes: The stator-rotor contact modeling module is used to obtain the contact conditions between the motion trajectory of the characteristic points on the rotor surface and the inner wall of the stator in different angle intervals according to the motion trajectory of the rotor surface; a wear calculation module, configured to calculate the geometric wear intensity of each feature point based on the contact conditions; The optimization module is used to optimize the rotor structure according to the geometric wear intensity to make the wear uniform.

[0059] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present application, and the present application is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present application, and such modifications and improvements are also considered to be within the scope of protection of the present application.

Claims

1. A screw pump rotor structure optimization method based on wear track quantification, characterized in that: include: S1, according to the motion trajectory of the rotor surface, obtain the contact situation between the motion trajectory of the characteristic point on the rotor surface and the inner wall of the stator in different angle intervals; S2, calculating the geometric wear intensity of each characteristic point according to the contact condition; S3, optimizing the rotor structure according to the geometric wear intensity to make the wear uniform.

2. The screw pump rotor structure optimization method based on wear track quantification according to claim 1 is characterized in that: Said S1 specifically includes: S101, selecting multiple feature points on the rotor surface, establishing a conversion relationship between the rotor feature points in the moving coordinate system X1O1Y1 and the fixed coordinate system XOY, and establishing a motion trajectory equation; S102, using the motion trajectory equation, solve the contact conditions between the motion trajectory of the characteristic point on the rotor surface and the inner wall of the stator in different angle intervals.

3. The screw pump rotor structure optimization method based on wear track quantification according to claim 2 is characterized in that: The conversion relationship in S101 is: ； in, θ is the rotation angle of the line connecting the rotor characteristic point and the moving coordinate system O1 to the moving coordinate system O1Y1 axis; Φ is the rotation angle of the line connecting the origin O1 of the moving coordinate system and the origin O of the fixed coordinate system with respect to the OY axis of the fixed coordinate system; t is the rotor pitch; e is the eccentricity of the rotor.

4. The screw pump rotor structure optimization method based on wear track quantification according to claim 1 is characterized in that: The S2 specifically includes calculating the wear stroke length of each feature point according to the contact situation l , according to the wear stroke length l Calculation of geometric wear intensity k ; The wear stroke length l for: ; The geometric wear strength k for: ; in, l 定 is the cross-sectional circumference of the stator inner wall; l 1. l 2 are the stator lengths of the two contact areas.

5. The screw pump rotor structure optimization method based on wear track quantification according to claim 1 is characterized in that: The S3 specifically includes: The rotor surface is divided into three areas: high-intensity wear area, transition wear area, and gentle wear area; For high-intensity wear areas, reduce the rotor radius; For the transition wear zone, a transition curve is used to achieve a smooth transition of the radius; For the gentle wear area, the original radius of the rotor is kept unchanged.

6. The screw pump rotor structure optimization method based on wear track quantification according to claim 5 is characterized in that: In the high-intensity wear zone, the reduced rotor radius is calculated as follows: ； in, ∆r The length that needs to be subtracted to optimize the rotor radius; k is the geometric wear strength; R is the radius of the unoptimized rotor; η is the adjustment coefficient.

7. The method for optimizing the screw pump rotor structure based on wear track quantification according to claim 5, characterized in that: The optimized rotor radius changes with the characteristic point position angle α The expression of the change is as follows: ； in, ∆r The length to be subtracted to optimize the rotor radius is: θ 1 is the first angle value, θ 2 is the second angle value; the position angle of the feature point 0≤α≤ θ 2 is located in the high-intensity wear area; the position angle of the characteristic point θ 2≤α≤ θ 1 is located in the transition wear zone; the position angle of the characteristic point θ When 1≤α≤180°, it is in the gentle wear zone.

8. The method for optimizing the screw pump rotor structure based on wear track quantification according to claim 7, characterized in that: The screw pump rotor structure optimization method further includes: An optimized rotor axial linear equation is obtained according to the optimized rotor radius, and the rotor is processed according to the rotor axial linear equation.

9. The method for optimizing the screw pump rotor structure based on wear track quantification according to claim 8, characterized in that: The optimized rotor axial linear equation is: ； When the rotor is of equal diameter, ; When the rotor is a conical rotor, ; in, D r1 is the diameter of the first end of the conical rotor, D r2 is the diameter of the second end of the conical rotor, L is the rotor length.

10. A screw pump rotor structure optimization system based on wear track quantification, characterized in that: The system can be used to implement the screw pump rotor structure optimization method based on wear track quantification as described in any one of claims 1 to 9 above, and the system includes: The stator-rotor contact modeling module is used to obtain the contact conditions between the motion trajectory of the characteristic points on the rotor surface and the inner wall of the stator in different angle intervals according to the motion trajectory of the rotor surface; a wear calculation module, configured to calculate the geometric wear intensity of each feature point based on the contact conditions; The optimization module is used to optimize the rotor structure according to the geometric wear intensity to make the wear uniform.

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