Method for using a pipe string vibration test device with an elastic support mechanism

Abstract

The present invention discloses a method for using a pipe string vibration test device with an elastic support mechanism, which belongs to the technical field of pipe string vibration testing. The pipe string vibration test device of the present invention includes an inner pipe string, an outer pipe string, and an elastic support mechanism arranged between the inner pipe string and the outer pipe string. The method for using the device includes the following steps: using finite element software to establish a finite element model of the inner pipe string, and determining the support position of the elastic support mechanism and the spring coefficient of the elastic support mechanism through a numerical simulation method; assembling the elastic support mechanism according to the spring coefficient of the elastic support mechanism and installing the elastic support mechanism according to the support position of the elastic support mechanism; after the pipe string vibration test device is installed, applying vibration to the inner pipe string to perform a pipe string vibration test. The present invention can prevent the inner pipe string from contacting the outer pipe string during the vibration test due to gravity deformation and the like, thereby affecting the test data.

Description

Technical Field

[0001] The present invention relates to the technical field of pipe string vibration testing, and in particular to a method for using a pipe string vibration testing device with an elastic support mechanism. Background Art

[0002] The injection and production tubing of gas storage facilities or oil wells can be subject to vibration caused by the internal fluid, posing a serious challenge to the lifespan of the tubing and the safe operation of the equipment. To study the impact of tubing vibration, tubing vibration tests are currently commonly conducted to analyze the vibration patterns of the tubing. Tubing vibration tests are conducted using scaled-down models. Although the prototype tubing and casing have been scaled, the model is still several meters long. Furthermore, the inner tubing of the simulated tubing is typically made of PE pipe, which has a certain degree of flexibility. Due to the influence of the tubing's aspect ratio and shape, the inner tubing of the simulated tubing can come into contact with the outer tubing of the simulated casing during vibration due to gravity, affecting the test data. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention proposes a method for using a pipe string vibration test device with an elastic support mechanism. By setting an elastic support mechanism between the inner pipe string and the outer pipe string to support the inner pipe string, the inner pipe string is prevented from being deformed by gravity and contacting the outer pipe string during the vibration test, thereby affecting the test data.

[0004] The present invention specifically adopts the following technical solutions:

[0005] A method for using a pipe string vibration test device having an elastic support mechanism, the pipe string vibration test device comprising an inner pipe string, an outer pipe string, and an elastic support mechanism disposed between the inner and outer pipe strings, the elastic support mechanism comprising an inner pipe string support bracket and at least two curved plates disposed circumferentially along the inner pipe string support bracket, the inner pipe string support bracket and the curved plates being connected via a spring;

[0006] The method of use comprises the steps of:

[0007] S1. Establish a finite element model of the inner string using finite element software, and determine the support position of the elastic support mechanism and the spring coefficient of the elastic support mechanism through numerical simulation methods;

[0008] S2, assembling the elastic support mechanism according to the spring coefficient of the elastic support mechanism determined in step S1 and installing the elastic support mechanism according to the supporting position of the elastic support mechanism determined in step S1;

[0009] S3. After the tubing string vibration test device is installed, vibration is applied to the inner tubing string to perform a tubing string vibration test.

[0010] Furthermore, the step S1 is specifically as follows:

[0011] S11. Establish a finite element model of the inner tubing string based on the structure and dimensions of the inner tubing string used in the tubing string vibration test device. Perform a static analysis after applying boundary conditions to obtain the natural deformation state of the inner tubing string under the action of gravity alone.

[0012] S12. Based on the static analysis results of step S11, preselect the pipe section with the largest deformation in the inner pipe string as the area requiring the application of the elastic support mechanism;

[0013] S13. Based on the finite element model of the inner pipe string established in step S11, an elastic support arc surface model for simulating the elastic support mechanism is added to the elastic support mechanism application area and the areas on both sides thereof preselected in step S12, and the elastic support force of the elastic support arc surface model is controlled by the foundation stiffness. The number, position and foundation stiffness of the elastic support arc surface models are adjusted by the orthogonal test method to perform static analysis, and the deformation cloud diagram of the inner pipe string under different support conditions is analyzed;

[0014] S14, comparing the inner pipe column deformation cloud maps under different support conditions obtained in step S13, and selecting the elastic support arc surface model quantity range, position range, and foundation stiffness range that can meet the inner pipe column deformation requirements;

[0015] S15. Perform modal analysis on the inner pipe string model without support and the inner pipe string model with the support conditions selected in step S14, obtain the changes in the first n natural frequencies of the inner pipe string before and after the support is applied, analyze and determine the degree of influence of the support on the natural frequency of the inner pipe string, and select the range of the number, position, and foundation stiffness of the elastic support arc surface models that can meet the requirements for the change in natural frequency;

[0016] S16. Determine the spring coefficient of the actual elastic support mechanism according to the basic stiffness range of the elastic support arc surface model determined in step S15.

[0017] Furthermore, the deformation requirement of the inner pipe string in step S14 is that the deformation of the inner pipe string after the support is applied is within 20% of the difference between the radius of the inner and outer pipe strings.

[0018] Furthermore, the requirement for the change of the natural frequency of the inner string in step S15 is that the difference between the natural frequency of each order of the inner string after the support is applied and the natural frequency of the corresponding order of the inner string before the support is applied is within 3 Hz.

[0019] Furthermore, the spring constant of the actual elastic support mechanism in step S16 is calculated using the following formula:

[0020] K = E × S;

[0021] Where K is the spring constant, E is the basic stiffness, and S is the area of ​​the elastically supported arc surface model.

[0022] Furthermore, the inner pipe column support bracket is arranged outside the inner pipe column and fits with the outer wall of the inner pipe column, and the outer wall of the arc plate fits with the inner wall of the outer pipe column.

[0023] Furthermore, the inner column support tube bracket is a circular tube bracket or a semicircular tube bracket.

[0024] Furthermore, the inner pipe column is a soft plastic pipe, and the outer pipe column is a hard plastic pipe and is formed by splicing together several sections of hard plastic pipe.

[0025] Furthermore, the inner and outer tubing strings include a vertical well section at the top, a horizontal section at the bottom, and a stabilizing section between the vertical well section and the horizontal section, and a curved deflection section between the vertical well section and the stabilizing section, and between the horizontal section and the stabilizing section;

[0026] The ends of the vertical well section and the horizontal section of the inner pipe string are fixed to the outer pipe string through fixing collars, and the inclination stabilizing section of the inner pipe string is supported by at least one elastic supporting mechanism.

[0027] Furthermore, the tubular string vibration test device further comprises a test fixture adapted to the mounting shape of the outer tubular string and an air compressor for applying vibration to the inner tubular string;

[0028] The test fixture is provided with a plurality of outer pipe column support brackets, the outer pipe column is sleeved in the outer pipe column support brackets, and a gasket is provided between the outer pipe column and the outer pipe column support brackets;

[0029] The air outlet of the air compressor is sealed and connected to one end of the inner pipe column.

[0030] The present invention has the following beneficial effects:

[0031] (1) The present invention provides a method for using a pipe string vibration test device having an elastic support mechanism, wherein the elastic support mechanism is provided between the inner pipe string and the outer pipe string to support the inner pipe string. The elastic force of the elastic support mechanism can maintain the inner pipe string at the center of the outer pipe string and keep the inner pipe string relatively stable during the vibration test, thereby preventing the inner pipe string from being deformed by gravity and coming into contact with the outer pipe string during the vibration test, thereby affecting the test data. At the same time, the elastic force of the elastic support mechanism is relatively small and will not affect the vibration of the inner pipe string.

[0032] (2) The elastic support mechanism provided by the present invention has a simple structure and is easy to install, and the support position can be adjusted according to actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1This is a schematic diagram of the overall structure of the pipe string vibration test device;

[0034] Figure 2 This is a schematic diagram of the structure of the outer pipe string support pipe bracket;

[0035] Figure 3 It is a structural schematic diagram of an elastic support mechanism in which the inner pipe column support tube is a circular tube support;

[0036] Figure 4 Schematic diagram of the structure of the elastic support mechanism of the inner pipe column support tube is a semicircular tube support;

[0037] Figure 5 for Figure 3 A schematic diagram of a structure in which an elastic support mechanism is installed between an inner pipe string and an outer pipe string;

[0038] Figure 6 for Figure 4 A schematic diagram of a structure in which an elastic support mechanism is installed between an inner pipe string and an outer pipe string;

[0039] Figure 7 This is the deformation cloud diagram of the inner string under unsupported conditions;

[0040] Figure 8 Schematic diagram of applying elastic supports at different positions of the stabilizing section of the inner string;

[0041] Figure 9 To apply a foundation stiffness of 0.001N / mm 3 The deformation cloud diagram of the inner pipe string after support;

[0042] Figure 10 To apply a foundation stiffness of 0.0015N / mm 3 Deformation cloud map of the inner pipe string after support.

[0043] Markings in the figure: 1. Inner tubular column; 2. Outer tubular column; 3. Elastic support mechanism; 301. Inner tubular column support bracket; 302. Arc plate; 303. Spring; 4. Test fixture; 5. Outer tubular column support bracket; 501. Outer tubular column upper support bracket; 502. Outer tubular column lower support bracket. DETAILED DESCRIPTION

[0044] The specific implementation of the present invention will be further described below with reference to the accompanying drawings and specific examples.

[0045] Reference Figure 1This embodiment provides a pipe string vibration test device with an elastic support mechanism, including an inner pipe string 1, an outer pipe string 2 sleeved on the outside of the inner pipe string 1, an elastic support mechanism 3 arranged between the inner pipe string 1 and the outer pipe string 2, and a test fixture 4 adapted to the installation shape of the outer pipe string 2. At least one of the above-mentioned elastic support mechanisms 3 is provided and is used to support the inner pipe string. The above-mentioned test fixture 4 is provided with a plurality of outer pipe string support pipe brackets 5 and is used to fix the outer pipe string. Specifically, the inner pipe string 1 is a soft plastic pipe, specifically a PE pipe; the outer pipe string 2 is a hard plastic pipe, specifically a transparent acrylic pipe, and the outer pipe string 2 is spliced ​​together by several sections of hard plastic pipes, and the adjacent two hard plastic pipes are connected by flanges at the ends of the pipes; the pipeline forms of the inner pipe string 1 and the outer pipe string 2 include a vertical well section located at the upper part, a horizontal section located at the lower part, and a stabilizing section between the vertical well section and the horizontal section, and there are curved inclination sections between the vertical well section and the stabilizing section, and between the horizontal section and the stabilizing section; the ends of the vertical well section and the horizontal section of the inner pipe string 1 are fixed to the outer pipe string 2 by fixing rings, and the stabilizing section of the inner pipe string 1 is supported by at least one elastic support mechanism 3 to prevent the inner pipe string 1 made of soft plastic from deforming due to gravity or contacting the outer pipe string 2 during vibration.

[0046] Reference Figure 2 The above-mentioned outer tubular column support tube holder 5 specifically includes an outer tubular column upper support tube holder 501 and an outer tubular column lower support tube holder 502. The outer tubular column upper support tube holder 501 and the outer tubular column lower support tube holder 502 are connected by bolts on both sides of the tube holder. The outer tubular column lower support tube holder 502 is fixedly connected to the test fixture 4. The outer tubular column 2 is fixed to the test fixture 4 by being sleeved in the outer tubular column support tube holder 5, and a gasket is provided between the outer tubular column 2 and the outer tubular column support tube holder 5.

[0047] Reference Figure 3 and Figure 4 The elastic support mechanism 3 specifically includes an inner column support bracket 301 and at least two curved plates 302 arranged along the circumference of the inner column support bracket 301, and the inner column support bracket 301 and the curved plates 302 are connected by a spring 303. The inner column support bracket 301 is specifically a circular bracket or a semicircular bracket. When the inner column support bracket 301 is a circular bracket, three curved plates 302 are provided, and two of the curved plates 302 are symmetrically arranged on the left and right sides of the inner column support bracket 301, and the other curved plate 302 is provided directly below the inner column support bracket 301. When the inner column support bracket 301 is a semicircular bracket, two curved plates 302 are provided, and the two curved plates 302 are symmetrically arranged on the lower left and lower right sides of the inner column support bracket 301. In addition, the inner diameter of the inner pipe column support bracket 301 matches the outer diameter of the inner pipe column 1 to ensure that the two are in close contact and can move along the inner pipe column when a thrust is applied.

[0048] Reference Figure 5 and Figure 6 The above-mentioned elastic support mechanism 3 is installed between the inner pipe column 1 and the outer pipe column 2, and the inner wall of the inner pipe column support tube 301 is in contact with the outer wall of the inner pipe column 1, and the outer wall of the arc plate 302 is in contact with the inner wall of the outer pipe column 2. The inner pipe column can be supported by the elastic support mechanism.

[0049] In addition, in order to facilitate the installation and fixation of the spring of the above-mentioned elastic support mechanism, the outer wall of the above-mentioned inner column support tube bracket 301 and the inner wall of the arc plate 302 are provided with mounting holes for installing and fixing the spring. One end of the spring is fixed in the mounting hole on the outer wall of the inner column support tube bracket, and the other end is fixed in the mounting hole on the inner wall of the arc plate.

[0050] In addition, the tubular string vibration test apparatus of this embodiment further includes an air compressor (not shown) for applying vibration to the inner tubular string 1, with the air outlet of the air compressor being sealedly connected to one end of the inner tubular string 1. Furthermore, a number of vibration sensors (not shown) for monitoring the vibration of the inner tubular string 1 are arranged along the length of the inner tubular string 1. Compressed air is applied to the inner tubular string 1 to simulate tubular string vibration, and vibration data from different regions of the inner tubular string are monitored via the vibration sensors.

[0051] The elastic support mechanism is not directly applied during application. Instead, its support position, number, and spring stiffness must be determined to ensure that the elastic support mechanism supports the inner pipe string while minimizing the impact on the inner pipe string's vibration. Therefore, this embodiment first uses finite element software to establish a finite element model of the inner pipe string. Numerical simulation methods are used to determine the support position of the elastic support mechanism and the spring stiffness of the elastic support mechanism. The specific steps are as follows:

[0052] S11. Establish a finite element model of the inner tubing string based on the structure and dimensions of the inner tubing string used in the tubing string vibration test device. Perform a static analysis after applying boundary conditions to obtain the natural deformation state of the inner tubing string under the action of gravity alone.

[0053] S12. Based on the static analysis results of step S11, preselect the pipe section with the largest deformation in the inner pipe string as the area requiring the application of the elastic support mechanism;

[0054] S13. Based on the finite element model of the inner pipe string established in step S11, an elastic support arc surface model for simulating the elastic support mechanism is added to the elastic support mechanism application area and the extended areas on both sides preselected in step S12, and the elastic support force of the elastic support arc surface is controlled by the foundation stiffness. The number and position of the elastic support arc surface models and the foundation stiffness are adjusted by the orthogonal test method to perform static analysis, and analyze the deformation cloud diagram of the inner pipe string under different support conditions;

[0055] S14. Compare the inner string deformation cloud maps under different support conditions obtained in step S13, and select a support condition that can meet the inner string deformation requirements, namely, the range of the number and position of the elastic support arc surface models and the range of the foundation stiffness. Specifically, the inner string deformation requirement is that the deformation of the inner string after the support is applied is within 20% of the difference between the inner and outer string radii.

[0056] S15. Perform modal analysis on the inner string model without support and the inner string model with the support conditions selected in step S14, obtain the changes in the first n natural frequencies of the inner string before and after the support is applied, analyze and determine the degree of influence of the support on the natural frequency of the inner string, and select support conditions that meet the requirements for the change in natural frequency. Specifically, the requirement for the change in natural frequency of the inner string is that the difference between the natural frequency of each order of the inner string after the support is applied and the natural frequency of the corresponding order of the inner string before the support is applied is within 3 Hz. The support conditions selected in this step can simultaneously meet the requirements for the deformation of the inner string and the requirements for the change in natural frequency.

[0057] S16. Determine the spring coefficient of the actual elastic support mechanism according to the basic stiffness range of the elastic support arc surface model determined in step S15; and the spring coefficient of the actual elastic support mechanism is calculated by the following formula:

[0058] K = E × S;

[0059] Where K is the spring constant, E is the basic stiffness, and S is the area of ​​the elastically supported arc surface model.

[0060] Based on the above steps, the support position, quantity and spring stiffness coefficient of the elastic support mechanism in the pipe string vibration test device of this embodiment are determined. Figure 4 The elastic support mechanism shown has an outer diameter of the inner tube column of 20 mm, an inner diameter of the outer tube column of 60 mm, and a total length of 5250 mm.

[0061] In this embodiment, a finite element model of the inner string is first established based on the structure and dimensions of the inner string used in the string vibration test device. After applying boundary conditions, a static analysis is performed to obtain the natural deformation state of the inner string under the action of gravity alone, as shown in FIG. Figure 7 shown; according to Figure 7 From the static analysis results, it can be seen that the section of the inner pipe with the largest deformation is mainly concentrated in the stable inclination section, and the middle part of the stable inclination section has the largest deformation, with a maximum deformation of 15.75mm. The middle part of the stable inclination section with the largest deformation of the inner pipe is pre-selected as the area where the elastic support mechanism needs to be applied.

[0062] Based on the above determination that the area with the largest deformation of the inner string in the natural deformation state is the middle part of the stable inclination section, the range of support position selection is expanded, that is, the elastic support mechanism area is applied to the pre-selected middle part of the stable inclination section and the elastic support arc surface model (contact area of ​​100mm) for simulating the elastic support mechanism is added to the extended area of ​​the stable inclination section on both sides. 2 ),like Figure 8 The figure shows a schematic diagram of applying elastic support at different positions of the stable inclination section of the inner pipe string. Specifically, the elastic support arc surface model can be applied at one, two, or more than two positions from position a to position i, and on this basis, the basic stiffness of the elastic support arc surface model is adjusted to obtain different support condition combinations, and static analysis is performed on the different support conditions to obtain the deformation cloud map of the inner pipe string under different support conditions. The number range, position range, and basic stiffness range of the elastic support arc surface model that can make the deformation of the inner pipe string within 20% of the difference between the inner and outer pipe string radii (that is, the deformation within 4 mm) are selected; among them, the elastic support arc surface model is applied at the middle position of the stable inclination section of the inner pipe string (that is, position e), and the initial basic stiffness is set to 0.001N / mm 3 After static analysis, we get Figure 9 The deformation cloud diagram of the inner pipe column shows that under this support condition, the maximum deformation of the inner pipe column is 4.54mm. After the support is applied, the overall deformation of the inner pipe column is significantly reduced, but the deformation is still large and does not meet the deformation requirement of the inner pipe column. The foundation stiffness is further adjusted to 0.0015N / mm at this position. 3 And perform static analysis to obtain Figure 10 As shown in the deformation cloud diagram of the inner pipe column, the maximum deformation of the inner pipe column as a whole under the support condition is 3.86mm, which meets the requirements. In addition, when setting the basic stiffness, the spring coefficient parameters of common stainless steel springs can also be used to obtain the selection range of the basic stiffness. If the outer diameter and effective number of turns of the support spring are fixed, respectively, 10mm and 4 turns, its spring coefficient is controlled by the wire diameter. The spring spring coefficient range under this condition is shown in Table 1 below. This table only explains the spring coefficients of springs with different wire diameters under fixed outer diameters and number of turns, so as to determine the selection range of the basic stiffness. The outer diameter and number of turns can also be adjusted to determine the range of the basic stiffness.

[0063] Table 1 Basic stiffness corresponding to different spring coefficients

[0064]

[0065] After applying elastic support, the natural frequency of the inner string will change. Therefore, modal analysis is continued on the inner string model without support and the inner string model with different support conditions to obtain the changes in the first ten natural frequencies of the inner string before and after support. Among them, the arc surface model with no support and elastic support applied at the middle position of the inner string stable section (i.e., position e) is used, and the foundation stiffness is set to 0.0015N / mm. 3 The first ten natural frequencies of the inner string are shown in Table 2. The difference between the natural frequency of each order of the inner string after the support is applied and the natural frequency of the corresponding order of the inner string before the support is applied is within 3 Hz, indicating that the influence of the support on the natural frequency of the inner string is acceptable.

[0066] Table 2 The first ten natural frequencies before and after support application

[0067]

[0068] Furthermore, the natural frequency can also, to a certain extent, reflect the forced vibration characteristics of the inner string. When the natural frequency changes little after applying the support (within 3 Hz), it indicates that the elastic support has little effect on the forced vibration of the inner string. This is because the foundation stiffness of the elastic support is low, and the elastic force it provides is relatively small, thus having little effect on the vibration of the inner string.

[0069] Finally, the basic stiffness of the elastic support curved surface model is 0.0015N / mm 3 The spring constant used in the actual elastic support mechanism is determined to be K=E×S=0.15N / mm. Based on the spring constant, the spring specifications can also be determined using the following formula or Table 1:

[0070] ;

[0071] Where G is the rigidity modulus of the spring wire, d is the wire diameter of the spring, N is C is the effective number of circles, D m The median diameter.

[0072] According to the common stainless steel spring coefficients in Table 1, the spring of the elastic support mechanism is selected to be a stainless steel spring with a rigidity modulus G=7200, a spring wire diameter of 0.5mm, a total number of turns of 6, an effective number of turns of 4, an outer diameter of 10mm, and a length of 15mm (the spring length is determined according to the annular space distance between the inner and outer pipe strings. There is a 20mm annular space between the inner and outer pipe strings. Excluding the thickness of the pipe support and the arc plate, the final spring length is determined to be 15mm). The spring coefficient of this spring is 0.16N / mm, which is basically the same as 0.15N / mm.

[0073] Based on the above-mentioned simulation method for determining the support position, number and spring stiffness coefficient, the elastic support mechanism is first assembled according to the determined spring stiffness coefficient used by the elastic support mechanism, and then the elastic support mechanism is put on the inner pipe column according to the determined support position of the elastic support mechanism. Since the outer diameter of the inner pipe column support pipe bracket on the elastic support mechanism matches the inner diameter of the inner pipe column, the two are firmly combined after installation and will not move under the action of large external force. At the same time, the vibration sensor is fixed to the outer wall of the inner pipe column; after the elastic support mechanism and the vibration sensor are installed, the outer pipe column is installed. When installing the outer pipe column, multiple acrylic tubes are first put on the outside of the inner pipe column, and then the multiple acrylic tubes are fixed together through flanges and bolts; finally, the installed inner and outer pipe columns are fixed to the test fixture through the outer pipe column support pipe bracket. After checking that the installation is correct, an air compressor is used to apply vibration to the inner pipe column to perform a pipe column vibration test. At the same time, the vibration sensor monitors the vibration data of the inner pipe column.

[0074] During the above-mentioned pipe string vibration test, no contact between the inner pipe string and the outer pipe string occurred, thereby improving the accuracy of the monitoring data of the vibration sensor.

[0075] In addition, in actual oil and gas well production, annular space protection fluid is injected between the oil pipe and the casing. The annular space protection fluid will form annular space pressure between the oil pipe and the casing. This embodiment can also adjust the basic stiffness of the elastic support mechanism according to the annular space pressure on the basis of providing support for the deformation of the inner pipe string due to gravity, thereby simulating the effect of the annular space protection fluid between the actual oil pipe and the casing, and more realistically simulating the actual working conditions.

[0076] It should be noted that the parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0077] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A method for using a pipe string vibration test device with an elastic support mechanism, characterized in that: The tubular column vibration test device includes an inner tubular column, an outer tubular column, and an elastic support mechanism disposed between the inner tubular column and the outer tubular column. The elastic support mechanism includes an inner tubular column support bracket and at least two arc-shaped plates disposed circumferentially along the inner tubular column support bracket. The inner tubular column support bracket and the arc-shaped plates are connected via a spring. The method of use comprises the steps of: S1. Establish a finite element model of the inner string using finite element software, and determine the support position of the elastic support mechanism and the spring coefficient of the elastic support mechanism through numerical simulation methods; S2, assembling the elastic support mechanism according to the spring coefficient of the elastic support mechanism determined in step S1 and installing the elastic support mechanism according to the supporting position of the elastic support mechanism determined in step S1; S3. After the tubing string vibration test device is installed, vibration is applied to the inner tubing string to perform a tubing string vibration test; The step S1 is specifically as follows: S11. Establish a finite element model of the inner tubing string based on the structure and dimensions of the inner tubing string used in the tubing string vibration test device. Perform a static analysis after applying boundary conditions to obtain the natural deformation state of the inner tubing string under the action of gravity alone. S12. Based on the static analysis results of step S11, preselect the pipe section with the largest deformation in the inner pipe string as the area requiring the application of the elastic support mechanism; S13. Based on the finite element model of the inner pipe string established in step S11, an elastic support arc surface model for simulating the elastic support mechanism is added to the elastic support mechanism application area and the areas on both sides thereof preselected in step S12, and the elastic support force of the elastic support arc surface model is controlled by the foundation stiffness. The number, position and foundation stiffness of the elastic support arc surface models are adjusted by the orthogonal test method to perform static analysis, and the deformation cloud diagram of the inner pipe string under different support conditions is analyzed; S14, comparing the inner pipe column deformation cloud maps under different support conditions obtained in step S13, and selecting the elastic support arc surface model quantity range, position range, and foundation stiffness range that can meet the inner pipe column deformation requirements; S15. Perform modal analysis on the inner pipe string model without support and the inner pipe string model with the support conditions selected in step S14, obtain the changes in the first n natural frequencies of the inner pipe string before and after the support is applied, analyze and determine the degree of influence of the support on the natural frequency of the inner pipe string, and select the range of the number, position, and foundation stiffness of the elastic support arc surface models that can meet the requirements for the change in natural frequency; S16. Determine the spring coefficient of the actual elastic support mechanism according to the basic stiffness range of the elastic support arc surface model determined in step S15.

2. The method for using the pipe string vibration test device with an elastic support mechanism according to claim 1, characterized in that: The deformation requirement of the inner pipe string in step S14 is: the deformation of the inner pipe string after the support is applied is within 20% of the difference between the inner and outer pipe string radii.

3. The method for using the pipe string vibration test device with an elastic support mechanism according to claim 1, characterized in that: The requirement for the change of the natural frequency of the inner pipe string in step S15 is that the difference between the natural frequency of each order of the inner pipe string after the support is applied and the natural frequency of the corresponding order of the inner pipe string before the support is applied is within 3 Hz.

4. The method for using the pipe string vibration test device with an elastic support mechanism according to claim 1, characterized in that: The spring constant of the actual elastic support mechanism in step S16 is calculated using the following formula: K = E × S; Where K is the spring constant, E is the basic stiffness, and S is the area of ​​the elastically supported arc surface model.

5. The method for using the pipe string vibration test device with an elastic support mechanism according to claim 1, characterized in that: The inner pipe column support bracket is arranged outside the inner pipe column and fits with the outer wall of the inner pipe column, and the outer wall of the arc plate fits with the inner wall of the outer pipe column.

6. The method for using the pipe string vibration test device with an elastic support mechanism according to claim 1, characterized in that: The inner pipe column support tube bracket is a circular tube bracket or a semicircular tube bracket.

7. The method for using the pipe string vibration test device with an elastic support mechanism according to claim 1, characterized in that: The inner pipe column is a soft plastic pipe, and the outer pipe column is a hard plastic pipe and is formed by splicing together several sections of hard plastic pipes.

8. The method for using the pipe string vibration test device with an elastic support mechanism according to claim 1, characterized in that: The inner and outer tubing strings include a vertical well section at the top, a horizontal section at the bottom, and a stabilizing section between the vertical well section and the horizontal section, and a curved deflection section between the vertical well section and the stabilizing section and between the horizontal section and the stabilizing section; The ends of the vertical well section and the horizontal section of the inner pipe string are fixed to the outer pipe string through fixing collars, and the inclination stabilizing section of the inner pipe string is supported by at least one elastic supporting mechanism.

9. The method for using the pipe string vibration test device with an elastic support mechanism according to claim 1, characterized in that: The pipe string vibration test device also includes a test fixture adapted to the mounting shape of the outer pipe string and an air compressor for applying vibration to the inner pipe string; The test fixture is provided with a plurality of outer pipe column support brackets, the outer pipe column is sleeved in the outer pipe column support brackets, and a gasket is provided between the outer pipe column and the outer pipe column support brackets; The air outlet of the air compressor is sealed and connected to one end of the inner pipe column.

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