Petroleum pipe coupling thickness measuring device and measuring method thereof, and method for analyzing coupling strength of petroleum pipe coupling

Abstract

This invention discloses a device and method for measuring the thickness of oil pipe couplings, as well as a method for analyzing the connection strength of oil pipe couplings, belonging to the field of oil-specific thread testing technology. The oil pipe coupling thickness measuring device includes a mounting bracket, a digital display, a movable probe with a displacement sensor, and a fixed measuring shoe. The fixed measuring shoe includes a movable frame and a measuring shoe head mounted on the movable frame. The movable frame is telescopically connected to the mounting bracket, and the measuring shoe head is used to position the thread of the coupling to be measured. The movable probe with the displacement sensor is used to radially abut against the outer diameter of the coupling during thickness measurement. The displacement sensor on the movable side measures the coupling thickness based on the displacement change of the movable probe. This invention solves the problem in the prior art that there is no device for directly measuring coupling thickness and that coupling connection strength can be analyzed through coupling thickness measurement, achieving efficient and accurate measurement of oil pipe coupling thickness and reasonable analysis of coupling connection strength.

Description

Technical Field

[0001] This invention belongs to the field of petroleum-specific thread testing technology, and specifically relates to a petroleum pipe coupling thickness measuring device and its measuring method, and a method for analyzing the connection strength of petroleum pipe couplings. Background Technology

[0002] Oil well couplings connect tubing and casing to form oil well strings that can stretch for thousands of meters. As a critical connecting component in oil extraction, strict control over all thread parameters of the couplings is essential to ensure their quality and guarantee safe oil extraction. Coupling thickness is one of the most critical influencing factors. With increasing depth and environmental complexity in oil and gas extraction, the coupling, as the primary load-bearing component at the connection point, not only bears the weight of the tubing and casing but is also constantly subjected to torque, tension, compression, and bending loads, leading to fatigue and failures such as coupling expansion and stress cracking. Therefore, measuring coupling thickness effectively ensures the quality and safety of the connection between the coupling and the tubing / casing, preventing failures. However, current technology typically involves manual measurement of coupling thickness using calipers, which is inefficient and inaccurate, and there is no precise instrument for directly measuring coupling thickness.

[0003] The quality of the threaded connection of the oil pipe coupling directly determines the performance of the casing and is a decisive factor affecting the overall quality of the casing. Therefore, analyzing the connection strength of the oil pipe coupling is essential for safe use. Existing methods for analyzing the connection strength of oil pipe couplings, such as using finite element analysis to study stress distribution and physical loading tests to simulate field conditions, suffer from problems such as high analysis costs and long processing times.

[0004] Therefore, to solve the above problems, this invention proposes an oil pipe coupling thickness measuring device, a measuring method, and a method for conveniently and quickly analyzing the connection strength of oil pipe couplings by measuring their thickness. Summary of the Invention

[0005] To address the problems raised in the background art, the main objective of this invention is to provide an oil pipe coupling thickness measuring device and its measuring method, as well as a method for analyzing the connection strength of oil pipe couplings.

[0006] To achieve the above objectives, the present invention provides a device for measuring the thickness of oil pipe couplings, the device comprising a mounting bracket, a digital display, a movable probe with a displacement sensor, and a fixed measuring shoe;

[0007] The mounting bracket includes a vertical support frame and a horizontal support plate;

[0008] The fixed measuring shoe includes a movable frame and a measuring shoe head mounted on the movable frame. The movable frame is arranged opposite to the horizontal support plate and is telescopically connected to the vertical support frame. The top support surface of the measuring shoe head is parallel to the coupling thread surface and is used to locate the position of the coupling thread to be measured.

[0009] The movable probe with displacement sensor is fixedly connected to the horizontal support plate and is used to radially abut against the outer diameter of the coupling when measuring the coupling thickness. The displacement sensor on the movable side head measures the coupling thickness according to the displacement change of the movable probe.

[0010] The digital display is mounted on the horizontal support plate to display the measured value of the coupling thickness.

[0011] In another aspect, the present invention provides a method for measuring the thickness of an oil pipe coupling using the aforementioned oil pipe coupling thickness measuring device, comprising the following steps: placing the oil pipe coupling between a movable probe and a fixed probe shoe; adjusting the probe shoe head of the fixed probe shoe via a movable bracket to extend into the oil pipe coupling at position t1 of the thread to be measured; moving the movable probe, equipped with a displacement sensor, accordingly to position t1 of the oil pipe coupling thread to be measured and abutting against the outer diameter of the coupling to measure the coupling thickness at position t1; taking position t1 as the origin, rotating by an angle θ to measure the coupling thickness at different locations each time; summing the collected n coupling thickness results and taking the average value to obtain the oil pipe coupling thickness; the calculation formula for the oil pipe coupling thickness is as follows:

[0012]

[0013] In the formula, The value represents the average thickness of the coupling in mm; i represents the measurement position; n represents the number of measurements, which is 360° / θ.

[0014] Furthermore, at the position t1 of the thread to be tested on the oil pipe coupling, take half of the complete thread of the oil pipe coupling.

[0015] Furthermore, when the oil pipe coupling thread is a trapezoidal thread, the rotation angle θ is 36 to 60°, and the number of times n is 6 to 10.

[0016] Furthermore, when the oil pipe coupling thread is a round thread, the rotation angle θ is 45 to 90°, and the number of times n is 4 to 8.

[0017] In another aspect, the present invention provides a method for analyzing the connection strength of oil pipe couplings, wherein the thickness of the oil pipe coupling is obtained by the method for measuring the thickness of the oil pipe coupling as described in any one of claims 2 to 5.

[0018] Obtain the thickness t of the oil pipe coupling before threading. s That is, the nominal value of the thickness of the oil pipe coupling;

[0019] Based on the thickness of oil pipe couplings Thickness t of oil pipe coupling before threading s Calculate the connection strength P based on the thickness of the oil pipe coupling;

[0020] The calculated connection strength P of the oil pipe coupling thickness is compared with the connection strength P of the oil pipe coupling before threading. b A ratio is calculated, and the connection strength of the oil pipe coupling is analyzed based on the result of the ratio.

[0021] Furthermore, the connection strength P of the oil pipe coupling thickness is calculated using formula (2), which is as follows:

[0022]

[0023] In formula (2), P is the connection strength in MPa; U is the yield strength in MPa; K is the connection coefficient, ranging from 0.6 to 1.0; C is the material coefficient, ranging from 0.8 to 1.2; F is the safety factor, ranging from 0.8 to 0.9; and the thickness of the oil pipe coupling is... Thickness t of oil pipe coupling before threading s That is, the nominal value of the thickness of the oil pipe coupling.

[0024] Furthermore, the connection strength of the oil pipe coupling is analyzed based on the result of the ratio, including: if the result of the ratio satisfies formula (3), it means that the connection strength of the oil pipe coupling meets the usage requirements; otherwise, it means that it does not meet the usage requirements.

[0025]

[0026] In formula (3), S1 is the area of ​​the threaded portion of the oil pipe coupling within one pitch, and S2 is the area of ​​the gap portion of the oil pipe coupling within one pitch; P b The connection strength of the oil pipe coupling before threading is the design value from the pipe manufacturer.

[0027] Furthermore, when the oil pipe coupling is a trapezoidal thread coupling, the value of S1 / (S1+S2) should not be less than 0.40.

[0028] Furthermore, when the oil pipe coupling is a round thread coupling, the value of S1 / (S1+S2) should not be less than 0.49.

[0029] Compared with the prior art, the present invention has the following beneficial effects: The present invention solves the problem that there is no device for directly measuring the thickness of couplings and the problem of analyzing the connection strength of couplings through the thickness of couplings in the prior art, and realizes efficient and accurate measurement of the thickness of oil pipe couplings and reasonable analysis of the connection strength of couplings. Attached Figure Description

[0030] Figure 1 A schematic diagram of the structure of an oil pipe coupling thickness measuring device according to one embodiment of the present invention is shown.

[0031] Figure 2 The thickness of the oil pipe coupling measured according to the present invention is shown;

[0032] Figure 3 The ratio of the threaded portion area to the void portion area is shown within a pitch range of a trapezoidal threaded oil pipe coupling.

[0033] Figure 4 This shows the ratio of the area of ​​the threaded portion to the area of ​​the void portion within a pitch range of a round thread oil pipe coupling.

[0034] The above-mentioned attached figures include the following reference numerals: 1. Digital display, 2. Movable probe, 3. Vertical support frame, 4. Horizontal support plate, 5. Movable frame, 6. Measuring shoe. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the embodiments of this application.

[0036] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a replaceable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0038] To address the aforementioned problems, the first aspect of this invention discloses a device for measuring the thickness of oil pipe couplings, such as... Figure 1 As shown, it includes a mounting bracket, a digital display 1, a movable probe 2 with a displacement sensor, and a fixed measuring shoe. The mounting bracket includes a vertical support frame 3 and a horizontal support plate 4.

[0039] The fixed measuring shoe includes a movable frame 5 and a measuring shoe head 6 installed on the movable frame. The movable frame 5 is arranged opposite to the horizontal support plate 4 and is telescopically connected to the vertical support frame 3. The top support surface of the measuring shoe head 6 is parallel to the coupling thread surface and is used to position the coupling thread to be measured.

[0040] The movable probe 2 with a displacement sensor is fixedly connected to the horizontal support plate 4 and is used to radially abut against the outer diameter of the coupling when measuring the coupling thickness. The displacement sensor measures the coupling thickness based on the displacement change of the movable probe.

[0041] The digital display 1 is mounted on the horizontal support plate 4 to display the measured value of the coupling thickness.

[0042] like Figure 2 As shown, the measured thickness of the oil pipe coupling is the sum of the height from the coupling end face to the bottom of the thread tooth and the thread height, which is the height of t2 in the figure.

[0043] A second aspect of the present invention discloses a method for measuring the thickness of oil pipe couplings using an oil pipe coupling thickness measuring device, comprising the following steps:

[0044] The oil pipe coupling is placed between the movable probe and the fixed probe shoe. The probe shoe head of the fixed probe shoe is adjusted via the movable bracket to extend into the oil pipe coupling at position t1 of the thread to be measured. The movable probe, equipped with a displacement sensor, moves accordingly to position t1 of the oil pipe coupling thread and rests against the outer diameter of the coupling to measure the coupling thickness at position t1. Taking position t1 as the origin, the coupling thickness is measured at different locations by rotating by an angle θ each time. The n collected coupling thickness results are summed, and the average value is taken to obtain the oil pipe coupling thickness. The calculation formula for the oil pipe coupling thickness is as follows:

[0045]

[0046] In the formula, The value represents the average thickness of the coupling in mm; i represents the measurement position; n represents the number of measurements, which is 360° / θ.

[0047] To more accurately measure the thickness of the coupling, measurements need to be taken at different positions along the entire circumference of the coupling. In some specific embodiments of the present invention, when the oil pipe coupling thread is a trapezoidal thread, the rotation angle θ is 36–60°, and the number of times n is 6–10; when the oil pipe coupling thread is a round thread, the rotation angle θ is 45–90°, and the number of times n is 4–8.

[0048] In a specific embodiment of the present invention, the oil pipe coupling thread to be tested is located at position t1, which is half of the complete thread of the oil pipe coupling.

[0049] A third aspect of the present invention discloses a method for analyzing the connection strength of oil pipe couplings, comprising the following steps:

[0050] The thickness of the oil pipe coupling is obtained using the aforementioned method for measuring the thickness of the oil pipe coupling.

[0051] Obtain the thickness t of the oil pipe coupling before threading. s That is, the nominal value of the thickness of the oil pipe coupling;

[0052] Based on the thickness of oil pipe couplings Thickness t of oil pipe coupling before threading s Calculate the connection strength P based on the thickness of the oil pipe coupling;

[0053] The calculated connection strength P of the oil pipe coupling thickness is compared with the connection strength P of the oil pipe coupling before threading. b A ratio is calculated, and the connection strength of the oil pipe coupling is analyzed based on the result of the ratio.

[0054] In a specific embodiment of the present invention, the connection strength P of the oil pipe coupling thickness is calculated using formula (2), which is as follows:

[0055]

[0056] In formula (2), P is the connection strength in MPa; U is the yield strength in MPa; K is the connection coefficient, ranging from 0.6 to 1.0; C is the material coefficient, ranging from 0.8 to 1.2; F is the safety factor, ranging from 0.8 to 0.9; and the thickness of the oil pipe coupling is... Thickness t of oil pipe coupling before threading s That is, the nominal value of the thickness of the oil pipe coupling.

[0057] In a specific embodiment of the present invention, the connection strength of the oil pipe coupling is analyzed based on the result of the ratio, including:

[0058] If the result of the ratio satisfies formula (3), it means that the connection strength of the oil pipe coupling meets the usage requirements; otherwise, it means that it does not meet the usage requirements.

[0059]

[0060] In formula (3), S1 is the area of ​​the threaded portion of the oil pipe coupling within one pitch, and S2 is the area of ​​the gap portion of the oil pipe coupling within one pitch; P b The connection strength of the oil pipe coupling before threading is the design value from the pipe manufacturer.

[0061] The connection strength of oil pipe couplings is affected by various factors, the main influencing factors being pipe material, yield strength, pipe thickness, thread profile, etc. K is the connection coefficient, which is related to the fit between the coupling and pipe materials, thread shape, tightening torque, etc. C is the material coefficient, which is related to differences in mechanical properties, heat treatment state, surface quality, etc. F is the safety factor, ensuring a certain safety margin in application. Combining these influencing factors, the inventors, based on long-term experience, obtained the empirical formula of the above formula (2) to calculate the connection strength P of the oil pipe coupling thickness. Since the coupling has oil threads, its connection strength should be between the strength of the coupling before processing and the strength of the coupling without threads after processing. Figure 3 , Figure 4 As shown, within one pitch, the threaded portion is S1, and the clearance portion is S2. Based on the principle that the larger the effective area of ​​the thread, the greater the strength, the connection strength P of the oil pipe coupling thickness is related to the connection strength P of the oil pipe coupling before thread machining. b It should be greater than S1 / (S1+S2).

[0062] In some specific embodiments of the present invention, based on actual application measurements, when the oil pipe coupling is a trapezoidal thread coupling, the value of S1 / (S1+S2) should not be less than 0.40; when the oil pipe coupling is a round thread coupling, the value of S1 / (S1+S2) should not be less than 0.49, so as to effectively ensure the connection strength of the coupling and ensure the safety of oilfield operations.

[0063] The following is an example in which the thickness of the coupling of the object is measured and calculated according to the steps and processes described above in this invention, and the connection strength is analyzed by measuring the coupling thickness.

[0064] Example

[0065] For a trapezoidal threaded coupling with a specification of 5-1 / 2 mm, steel grade J55, and wall thickness of 7.72 mm, the aforementioned apparatus and method of this invention are used, and the following steps are followed:

[0066] Step 1: Measure and calculate the thickness of the coupling.

[0067] The thickness of the oil pipe coupling was measured at 1 / 2 of the complete thread using the aforementioned oil pipe coupling thickness measuring device. For the trapezoidal thread, the thickness was measured once by rotating 45° in the same direction, for a total of 8 measurements.

[0068] Measurements showed that the thicknesses of the couplings in the eight tests were 9.469mm, 9.472mm, 9.466mm, 9.468mm, 9.469mm, 9.473mm, 9.468mm, and 9.467mm, respectively.

[0069] Calculated according to formula (1)

[0070] Step 2: Analyze the connection strength of the coupling.

[0071] The design value for the connection strength of this coupling by the oil pipe manufacturer is P. b =400Mpa.

[0072] For this type of coupling, the yield strength is 380 MPa, K is taken as 0.7, C as 0.8, F as 0.9, and t... s = 9.475mm.

[0073] The connection strength of the coupling is calculated to be P = 191.399 MPa according to formula (2).

[0074] According to formula (3), the ratio of the connection strength of the coupling to the design value is 0.478, which is greater than the value of S1 / (S1+S2) of 0.40. Therefore, the connection strength of the coupling meets the application standard and is judged to be qualified.

[0075] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. The present invention can also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of the present invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A petroleum pipe coupling thickness measuring device characterized by, The measuring device comprises a mounting bracket, a digital display meter, a movable measuring head with a displacement sensor and a fixed measuring shoe; The mounting bracket comprises a vertical support frame and a horizontal support plate; The fixed measuring shoe comprises a movable frame and a measuring shoe head mounted on the movable frame, the movable frame is arranged opposite to the horizontal support plate and is connected to the vertical support frame in an extending and retracting manner, and a top end support surface of the measuring shoe head is parallel to a thread surface of the coupling for positioning a thread position of the coupling to be measured; The movable measuring head with the displacement sensor is fixedly connected to the horizontal support plate and is used for abutting against an outer diameter of the coupling in a radial direction during thickness measurement of the coupling, and the displacement sensor on the movable measuring head measures the thickness of the coupling according to a displacement change of the movable measuring head; The digital display meter is arranged on the horizontal support plate and is used for displaying a measured value of the thickness of the coupling.

2. A method of measuring the thickness of a petroleum pipe coupling using the petroleum pipe coupling thickness measuring apparatus according to claim 1, characterized by, The method comprises the following steps: The oil pipe coupling is placed between the movable measuring head and the fixed measuring shoe, the measuring shoe head of the fixed measuring shoe is adjusted to extend into a thread t1 position of the oil pipe coupling through the movable frame, the movable measuring head with the displacement sensor is correspondingly moved to the thread t1 position of the oil pipe coupling and abuts against the outer diameter of the coupling to measure the thickness of the coupling at the t1 position, the thickness of the coupling at different positions is measured by taking the t1 position as a starting point and rotating by an angle θ each time, the n thicknesses of the coupling collected are summed up, and an average value is obtained as the thickness of the oil pipe coupling, and a calculation formula of the thickness of the oil pipe coupling is as follows: In the formula, wherein T is the average thickness of the coupling, in mm; i is the position of the measurement; n is the number of measurements, and 360° / θ.

3. The method of measuring the thickness of a petroleum coupling of claim 2, wherein, The t1 position of the thread of the oil pipe coupling is taken at a position of 1 / 2 of a complete thread of the oil pipe coupling.

4. The method of measuring the thickness of a petroleum coupling of claim 2 wherein, When the thread of the oil pipe coupling is a trapezoidal thread, the rotation angle θ is 36-60°, and the number n is 6-10.

5. The method of claim 2, wherein, When the thread of the oil pipe coupling is a round thread, the rotation angle θ is 45-90°, and the number n is 4-8.

6. A method of analyzing the joint strength of a petroleum pipe joint collar, characterized by, comprising the step of obtaining the thickness of the petroleum pipe coupling band by the method of measuring the thickness of the petroleum pipe coupling band according to any one of claims 2 to 5 Obtaining the thickness t of the oil pipe coupling before machining the thread s i.e. the nominal value of the thickness of the oil pipe coupling; Petroleum pipe connecting hoop thickness Petroleum pipe coupling thickness t before machining thread s The connecting strength P of the petroleum pipe coupling thickness is calculated The calculated connection strength P of the oil pipe coupling thickness is compared with the connection strength P of the oil pipe coupling before machining the thread b The ratio is calculated, and the connection strength of the oil pipe coupling is analyzed based on the result of the ratio.

7. The method according to claim 6, wherein a connection strength P of the thickness of the oil pipe coupling is calculated by using formula (2) as follows: In formula (2), P is the connection strength, in units of Mpa; U is the yield strength, in units of Mpa; K is the connection coefficient, with a value range of 0.6 to 1.0; C is the material coefficient, with a value range of 0.8 to 1.2; F is the safety coefficient, with a value range of 0.8 to 0.9; the thickness of the petroleum pipe connecting hoop The thickness t of the petroleum pipe connecting hoop before machining the thread s That is, the nominal value of the thickness of the petroleum pipe connecting hoop.

8. The method according to claim 6, wherein the connection strength of the oil pipe coupling is analyzed based on a result of the ratio, comprising: When the result of the ratio satisfies formula (3), it is indicated that the connection strength of the oil pipe coupling satisfies a use requirement, otherwise, it is indicated that the connection strength of the oil pipe coupling does not satisfy the use requirement; In formula (3), S1 is the threaded portion area of the petroleum pipe coupling within one pitch, S2 is the clearance portion area of the petroleum pipe coupling within one pitch; P b The connection strength of the petroleum pipe coupling before machining threads is designed for the pipe manufacturer.

9. The method of claim 8, wherein, When the oil pipe coupling is a trapezoidal thread coupling, the value of S1 / (S1+S2) should be not less than 0.

40.

10. The method of claim 6, wherein, When the oil pipe coupling is a round thread coupling, the value of S1 / (S1+S2) should be not less than 0.49.

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