Image measurement-based online measurement method and system for J value of oil well pipe coupling tightening

Abstract

The application discloses an online measurement method and system for J value of oil well pipe coupling tightening based on image measurement, industrial cameras are arranged above the coupling and the oil well pipe, the measurement range can cover two work stations of pre-tightening and dynamic tightening, at the pre-tightening work station, the industrial cameras collect images of the oil well pipe and the coupling in real time, and the distance value of the coupling screwed into the pipe end thread of the oil well pipe is calculated according to the image data; at the dynamic tightening work station, the industrial cameras collect images of the oil well pipe and the coupling in real time, the length of the coupling and the distance value of the coupling end face to the disappearing place of the pipe end thread of the oil well pipe are calculated according to the image data, and the J value is calculated in combination with the distance value of the coupling screwed into the pipe end thread of the oil well pipe in the pre-tightening link. The application adopts a non-contact online measurement method for the J value, high-speed cameras are installed on the oil well pipe coupling tightening work station to measure the tightening process in real time, position and size data of the oil well pipe and the coupling in the tightening process are obtained, and thus the J value is accurately calculated and obtained.

Description

Technical Field

[0001] This invention relates to measurement technology in the steel pipe production process, and more specifically, to an online measurement method and system for the J-value of oil well pipe coupling tightening based on image measurement. Background Technology

[0002] Oil well tubing plays a vital role in the petroleum industry, serving as its foundation. Its importance is not only reflected in its large volume and high cost, but more importantly, in the crucial relationship between its quality and performance and the development of the petroleum industry. Oil well tubing is connected via couplings. Before leaving the factory, couplings are pre-tightened to one end of the tubing. Upon arrival at the oilfield, the other end of the tubing is then screwed onto the coupling to achieve an extended, sealed connection, meeting the requirements of oilfield production operations. The J-value refers to the distance from the end face of the tubing body to the center face of the coupling. It is the assembly dimension of the thread fit between the tubing body and the coupling, reflecting the engagement length of the internal and external threads, the interference fit, etc., and determines the connection quality of the oil well tubing. It is a crucial process and quality control parameter in oil well tubing production, with clear technical standards and requirements both domestically and internationally.

[0003] Currently, in actual production, the measurement of the J-value of oil well pipe coupling tightening is entirely manual. Generally, a steel tape measure or depth caliper is used to measure the length from the pipe end face to one end of the coupling, and then the coupling length is measured with a vernier caliper. The J-value is then calculated. While some improved J-value measuring tools exist, these methods still require manual operation, resulting in slow measurement speed, low efficiency, inconsistent standards, and large errors, making it difficult to achieve full online coverage measurement. There are currently no mature technologies or methods for the online automatic measurement of the J-value of oil well pipe coupling tightening. Summary of the Invention

[0004] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide an online measurement method and system for the J-value of oil well pipe coupling tightening based on image measurement. This method employs a non-contact online measurement of the J-value by installing a high-speed camera at the oil well pipe coupling tightening station to measure the tightening process in real time, obtaining the position and dimension data of the oil well pipe and coupling during the tightening process, thereby accurately calculating the J-value.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] On the one hand, an online measurement method for the J-value of oil well pipe coupling tightening based on image measurement includes the following steps:

[0007] S1. Obtain the current diameter dimensions of the coupling and well casing;

[0008] S2. At the pre-tightening station, the length value of the end thread of the oil well pipe is acquired and obtained by an industrial camera;

[0009] S3. Then, the industrial camera is used to collect and obtain the length value of the coupling, the length value of the remaining thread at the end of the oil well pipe, and the length value of the coupling screwed into the oil well pipe.

[0010] S4. Transport the coupling and the well pipe to the dynamic tightening station;

[0011] S5. At the tightening station, the length of the remaining thread at the end of the oil well pipe is acquired and obtained by the industrial camera.

[0012] S6. During the dynamic tightening process, the industrial camera collects and obtains the remaining length value of the end of the oil well pipe. Combined with the remaining length value of the end of the oil well pipe in step S5, the length value of the coupling screwed into the oil well pipe during the dynamic tightening process is calculated. Then, combined with the length value of the coupling in step S3 and the length value of the coupling pre-screwed into the oil well pipe, the J value is calculated.

[0013] S7. After the tightening is completed, the final J value of the coupling is obtained.

[0014] Preferably, step S2 specifically includes:

[0015] At the start of pre-tightening, before the coupling and the well pipe have made contact, the well pipe is fixed by the clamping device. An image of the well pipe is captured by the industrial camera. The end thread data of the well pipe is identified and extracted from the image, and the starting position a and ending position b of the thread, as well as the length S of the thread, are calculated.

[0016] Preferably, step S3 specifically includes:

[0017] After pre-tightening is completed and the pre-tightening chuck disengages from the coupling, the industrial camera acquires an image of the coupling and the well pipe being screwed together. From the image, the length value of the coupling and the remaining length value at the end of the well pipe are identified and extracted. The positions d and c of the two ends of the coupling are calculated. Position c is also the intersection position of the coupling and the well pipe and the starting position of the remaining thread of the well pipe. Based on positions d, c, and b, the length value L of the coupling and the remaining thread length value S1 of the well pipe are calculated. Combining the thread length value S, the length value D1 of the coupling screwed into the well pipe is calculated as D1 = S - S1.

[0018] Preferably, step S5 specifically includes:

[0019] At the start of the tightening process, after the well pipe is fixed by the moving clamping device, the industrial camera captures an image of the coupling and the well pipe being screwed together. The remaining thread data of the coupling and the well pipe are identified and extracted from the image. The starting position c and the ending position b of the remaining thread of the well pipe are calculated. Based on the positions c and b, the length value S2 of the remaining thread at the start of the tightening process is calculated.

[0020] Preferably, step S6 specifically includes:

[0021] During the dynamic tightening process, the dynamic tightening chuck drives the coupling to be continuously screwed into the oil well pipe. The industrial camera captures images of the coupling and the oil well pipe in real time. The remaining thread data of the oil well pipe is identified and extracted from the images. The starting position c and the ending position b of the remaining thread of the oil well pipe are calculated. The length value S3 of the remaining thread is calculated based on the positions c and b. Combined with the length value S2, the length value D2 of the coupling screwed into the oil well pipe during the dynamic tightening process is calculated as D2 = S2 - S3. Then, combined with the length value L of the coupling and the length value D1 of the coupling screwed into the oil well pipe, the J value is calculated as L / 2 - D1 - D2.

[0022] On the other hand, an online measurement system for the J-value of well tubing coupling tightening based on image measurement includes:

[0023] An industrial camera is installed at the pre-tightening station and the dynamic tightening station to acquire images of the coupling and the oil well pipe in real time;

[0024] The signal interface unit is used to acquire control signals from the pre-tightening chuck, the movable tightening chuck, the fixed clamping device, and the movable clamping device.

[0025] A process signal interface unit is used to collect the diameter specification data of the coupling and the well pipe.

[0026] The J-value measurement unit is used to receive image data, control signals, and diameter specification data transmitted from the industrial camera, the signal interface unit, and the process signal interface unit, and to calculate the J-value.

[0027] The image-based online measurement system for the tightening J-value of oil well pipe couplings realizes the image-based online measurement method for the tightening J-value of oil well pipe couplings.

[0028] The present invention provides an online measurement method and system for the tightening J value of oil well pipe couplings based on image measurement. This method uses a non-contact approach to achieve online automatic measurement of the tightening J value of oil well pipe couplings. It can obtain J value data in real time during production line operation, which plays a good role in ensuring product quality and guiding production. At the same time, the system is easy to implement and use in actual production, and has strong practicality. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the online measurement method for the tightening J-value of oil well pipe couplings according to the present invention.

[0030] Figure 2 This is a schematic diagram of the pre-tightening station image acquisition in the online measurement method of J value of oil well pipe coupling tightening of the present invention, wherein (a) is a schematic diagram before pre-tightening operation and (b) is a schematic diagram after pre-tightening operation;

[0031] Figure 3 This is a schematic diagram of the image acquisition of the dynamic tightening station in the online measurement method of the J value of oil well pipe coupling tightening of the present invention, wherein (a) is a schematic diagram before the dynamic tightening operation and (b) is a schematic diagram after the dynamic tightening operation.

[0032] Figure 4 This is a schematic diagram of the framework of the online measurement system for the tightening J-value of oil well pipe couplings according to the present invention. Detailed Implementation

[0033] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] Combination Figures 1 to 4 As shown, the present invention provides an online measurement method for the J-value of oil well pipe coupling tightening based on image measurement, comprising the following steps:

[0035] S1. Collect the specifications of the current coupling 2 and oil well pipe 1, obtain the diameter dimensions of coupling 2 and oil well pipe 1, and calculate the corresponding image calibration data;

[0036] S2. At the pre-tightening station, after the oil well pipe 1 is clamped and fixed by the fixing clamping device 4, the image of the oil well pipe 1 is acquired by the industrial camera 7, the image data of the end thread of the oil well pipe 1 is identified and extracted, and the length value of the thread is calculated.

[0037] S3. After the pre-tightening is completed and the pre-tightening chuck 3 releases the coupling 2, the industrial camera 7 acquires image data of the coupling 2 and the oil well pipe 1 being screwed together, identifies and extracts image data of the remaining threads at the ends of the coupling 2 and the oil well pipe 1, and calculates the length value of the coupling 2, the length value of the remaining threads at the ends of the oil well pipe 1, and the length value of the coupling 2 being screwed into the oil well pipe 1.

[0038] S4. Transport coupling 2 and well pipe 1 to the dynamic tightening station;

[0039] S5. At the tightening station, after the oil well pipe 1 is clamped and fixed by the moving clamping device 6, the image data of the coupling 2 and the oil well pipe 1 are acquired by the industrial camera 7, the image data of the remaining threads of the coupling 2 and the oil well pipe 1 are identified and extracted, and the length of the remaining thread at the end of the oil well pipe 1 is calculated.

[0040] S6. During the dynamic tightening process, the image data of the coupling 2 and the oil well pipe 1 are acquired in real time by the industrial camera 7. The image data of the remaining thread at the end of the oil well pipe 1 is identified and extracted. The length value of the remaining thread at the end of the oil well pipe 1 is calculated. Combined with the length value of the remaining thread at the end of the oil well pipe 1 in step S5, the length value of the coupling 2 screwed into the oil well pipe 1 during the dynamic tightening process can be calculated. Combined with the length value of the coupling 2 in step S3 and the length value of the coupling 2 screwed into the oil well pipe 1 in the pre-tightening stage, the distance value from the end face of the oil well pipe 1 to the center of the coupling 2, i.e., the J value, is calculated.

[0041] The calculation method for the J value is described as follows: The J value is defined as the distance between the end face of the well pipe 1 and the center face of the coupling 2. The length of the pre-tightening coupling 2 screwed into the well pipe 1 plus the length of the dynamic tightening coupling 2 screwed into the well pipe 1 is the total length of the coupling 2 screwed into the well pipe 1. The J value is obtained by subtracting this total length from half the length of the coupling 2.

[0042] S7. After the tightening is completed, the final J value of coupling 2 is obtained.

[0043] By following the steps above, the tightening J value of the oil well pipe 1 and coupling 2 can be measured online.

[0044] The above step S2 specifically includes:

[0045] At the start of pre-tightening, before the coupling 2 and the well pipe 1 have made contact, after the well pipe 1 is fixed by the clamping device 4, an image of the well pipe 1 is acquired by the industrial camera 7. The end thread data of the well pipe 1 is identified and extracted from the image, and the starting position a and ending position b of the thread, as well as the thread length S, are calculated. Figure 2 As shown in (a).

[0046] The above step S3 specifically includes:

[0047] After pre-tightening, coupling 2 and well pipe 1 are screwed together. After the pre-tightening chuck 3 disengages from coupling 2, an image of coupling 2 and well pipe 1 screwed together is captured by industrial camera 7. The length value of coupling 2 and the remaining length value of the end of well pipe 1 are identified and extracted from the image. The positions d and c of the two ends of coupling 2 are calculated. Position c is also the junction position of coupling 2 and well pipe 1 and the starting position of the remaining thread of well pipe 1. Based on positions d, c, and b, the length value L of coupling 2 and the remaining thread length value S1 of well pipe 1 are calculated. Combining the length value S, the length value D1 of coupling 2 screwed into well pipe 1 is calculated as D1 = S - S1. Figure 2 As shown in (b).

[0048] The above step S5 specifically includes:

[0049] At the start of the tightening process, after the well pipe 1 is clamped and fixed by the movable clamping device 5, the industrial camera 7 captures an image of the coupling 2 and the well pipe 1 being screwed together. The remaining thread data of the coupling 2 and the well pipe 1 are identified and extracted from the image. The starting position c and the ending position b of the remaining thread of the well pipe 1 are calculated. Based on the positions c and b, the length value S2 of the remaining thread at the start of the tightening process is calculated.

[0050] The above step S6 specifically includes:

[0051] During the dynamic tightening process, the dynamic tightening chuck 5 drives the coupling 2 to be continuously screwed into the oil well pipe 1. The industrial camera 7 acquires images of the coupling 2 and the oil well pipe 1 in real time. The remaining thread data of the oil well pipe 1 is identified and extracted from the images. The starting position c and the ending position b of the remaining thread of the oil well pipe 1 are calculated. The length value S3 of the remaining thread is calculated based on the positions c and b. Combined with the length value S2 of the remaining thread at the beginning of the dynamic tightening, the length value D2 of the coupling 2 screwed into the oil well pipe 1 during the dynamic tightening process is calculated as D2 = S2 - S3. Then, combined with the length value L of the coupling 2 obtained in the pre-tightening stage and the length value D1 of the coupling 2 screwed into the oil well pipe 1, the distance value J from the end face of the oil well pipe 1 to the center of the coupling 2 can be calculated as J = L / 2 - D1 - D2, i.e., the J value.

[0052] See again Figure 4 As shown, the present invention also provides an online measurement system for the J-value of oil well pipe coupling tightening based on image measurement, comprising:

[0053] The industrial camera 7 is located above the tightening station of the oil well pipe 1 and the coupling 2. Its measurement range can cover both the pre-tightening and dynamic tightening stations. It is an image measurement device used to acquire images of the coupling 2 and the oil well pipe 1 in real time and transmit the data to the J-value measurement unit 10 in real time.

[0054] The signal interface unit 8 is a signal communication device used to collect control signals from the pre-tightening chuck 3, the moving tightening chuck 5, the fixed clamping device 4 and the moving clamping device 6, and transmit the control signals to the J-value measurement unit 10 in real time.

[0055] The process signal interface unit 9 is a data communication device used to collect the current diameter specification data of the coupling 2 and the well pipe 1, and transmit the data to the J value measurement unit 10 in real time.

[0056] J-value measurement unit 10 is an industrial computer device with functions such as image, signal and data acquisition, processing, analysis and recognition, and J-value calculation. It is used to receive image data, control signals and diameter specification data from industrial camera 7, signal interface unit 8 and process signal interface unit 9, and calculate the J-value.

[0057] The online measurement system for the J-value of oil well pipe coupling tightening based on image measurement, as described in this invention, realizes the online measurement method for the J-value of oil well pipe coupling tightening based on image measurement.

[0058] Continue to refer to Figure 4 As shown, the pre-tightening chuck 3 is the equipment for the pre-tightening station, used to tighten the coupling 2 onto the oil well pipe 1. It can clamp and drive the coupling 2 to rotate, and can also move horizontally. The fixed clamping device 4 is the equipment for the pre-tightening station, used to clamp and fix the oil well pipe 1, keeping it stationary in both rotational and horizontal directions. The movable tightening chuck 5 is the equipment for the movable tightening station, used to tighten the coupling 2 onto the oil well pipe 1. It can clamp and drive the coupling 2 to rotate, keeping its horizontal position fixed during rotation. The movable clamping device 6 is the equipment for the movable tightening station, used to clamp the oil well pipe 1, fixing it in the rotational direction, but allowing it to move horizontally.

[0059] This invention is based on an image measurement method. The actual length represented by each pixel in the image is related to the distance from the object being measured to the camera, so the camera needs to be calibrated before measurement. Since oil well pipes and couplings come in various diameter specifications, in order to ensure measurement accuracy, it is necessary to calibrate the products with the largest and smallest pipe diameter specifications. Then, based on the pipe diameter, image calibration data for the corresponding pipe diameter is obtained using an interpolation calculation method.

[0060] Example 1

[0061] For the online measurement method and procedure of the J-value for tightening oil well pipe couplings in this embodiment, please refer to the appendix. Figure 1 As shown, it includes the following steps:

[0062] Step 1: The J-value measurement unit 10 reads the diameter specifications of the current coupling 2 and oil well pipe 1 as 130mm and 120mm respectively through the process interface unit 9, and calculates the corresponding image calibration data as 0.021mm / pixel and 0.0212mm / pixel.

[0063] Step 2: After the pre-tightening begins, the J-value measurement unit 10 receives the clamping signal from the fixed clamping device 4 in real time through the signal interface unit 8. After receiving the clamping signal, the industrial camera 7 acquires an image of the oil well pipe 1, identifies and extracts the pipe end thread data of the oil well pipe 1 from the image, and calculates the length value of the thread S = 70 mm.

[0064] Step 3: After pre-tightening, the J-value measurement unit 10 receives the signal of the pre-tightening chuck 3 disengaging from the coupling 2 in real time through the signal interface unit 8. After receiving the signal, the industrial camera 7 acquires an image of the coupling 2 and the oil well pipe 1 screwed together. The data of the coupling 2 and the remaining thread data of the oil well pipe 1 are identified and extracted from the image. The length value of the coupling 2 L = 150 mm and the length value of the remaining thread of the oil well pipe 1 S1 = 47.5 mm are calculated. Combined with the thread section length value of the oil well pipe 1 S = 70 mm in Step 2, the length value of the coupling 2 screwed into the oil well pipe 1 D1 = S - S1 = 70 - 37.5 = 32.5 mm is calculated.

[0065] Step four: The coupling 2 and the well pipe 1 are transported from the pre-tightening station to the dynamic tightening station.

[0066] Step 5: After the tightening begins, the J-value measurement unit 10 receives the clamping signal from the moving clamping device 6 in real time through the signal interface unit 8. When the clamping signal is received, the industrial camera 7 acquires an image of the coupling 2 and the oil well pipe 1 being screwed together. The remaining thread data of the coupling and the oil well pipe are identified and extracted from the image, and the length value of the remaining thread segment S2 = 32.6 mm is calculated.

[0067] Step Six: During the dynamic tightening process, the J-value measuring unit 10 acquires images of the coupling 2 and the well pipe 1 in real time through the industrial camera 7. It identifies and extracts the remaining thread data of the well pipe 1 from the images, calculating the remaining thread length S3 = 2.9 mm. Combined with the remaining thread length S2 = 32.6 mm at the start of the dynamic tightening in Step Five, the length of the coupling 2 screwed into the well pipe 1 during the dynamic tightening process is calculated as D2 = S2 - S3 = 32.6 - 2.9 = 29.7 mm. Then, combining the coupling length L = 150 mm from Step Three and the length of the coupling 2 screwed into the well pipe 1 during the pre-tightening stage as D1 = 32.5 mm, the distance from the end face of the well pipe 1 to the center of the coupling 2 can be calculated as J = L / 2 - D1 - D2 = 150 / 2 - 32.5 - 29.7 = 12.8 mm, which is the J-value.

[0068] Step 7: The J-value measuring unit 10 receives a signal indicating whether the tightening has ended through the signal interface unit 8. If not, it continues to execute step 6. If yes, it ends the measurement and records the J-value in step 6, which is the final tightening J-value of the well pipe 1 and coupling 2 = 12.8 mm.

[0069] Example 2

[0070] For the online measurement method and procedure of the J-value for tightening oil well pipe couplings in this embodiment, please refer to the appendix. Figure 1 As shown, it includes the following steps:

[0071] Step 1: The J-value measurement unit 10 reads the diameter specifications of the current coupling 2 and oil well pipe 1 as 75mm and 67mm respectively through the process interface unit 9, and calculates the corresponding image calibration data as 0.022mm / pixel and 0.0223mm / pixel.

[0072] Step 2: After the pre-tightening begins, the J-value measurement unit 10 receives the clamping signal from the fixed clamping device 4 in real time through the signal interface unit 8. After receiving the clamping signal, the industrial camera 7 acquires an image of the oil well pipe 1, identifies and extracts the pipe end thread data of the oil well pipe 1 from the image, and calculates the length value of the thread S = 55mm.

[0073] Step 3: After pre-tightening, the J-value measurement unit 10 receives the signal of the pre-tightening chuck 3 disengaging from the coupling 2 in real time through the signal interface unit 8. After receiving the signal, the industrial camera 7 acquires an image of the coupling 2 and the oil well pipe 1 screwed together. The data of the coupling 2 and the remaining thread data of the oil well pipe 1 are identified and extracted from the image. The length value of the coupling 2 L = 125 mm and the length value of the remaining thread of the oil well pipe 1 S1 = 28.5 mm are calculated. Combined with the thread section length value of the oil well pipe 1 S = 55 mm in Step 2, the length value of the coupling 2 screwed into the oil well pipe 1 D1 = S - S1 = 55 - 28.5 = 26.5 mm is calculated.

[0074] Step four: The coupling 2 and the well pipe 1 are transported from the pre-tightening station to the dynamic tightening station.

[0075] Step 5: After the tightening begins, the J-value measurement unit 10 receives the clamping signal from the moving clamping device 6 in real time through the signal interface unit 8. When the clamping signal is received, the industrial camera 7 acquires an image of the coupling 2 and the oil well pipe 1 being screwed together. The remaining thread data of the coupling and the oil well pipe are identified and extracted from the image, and the length value of the remaining thread segment S2 = 26.4 mm is calculated.

[0076] Step Six: During the dynamic tightening process, the J-value measuring unit 10 acquires images of the coupling 2 and the well pipe 1 in real time through the industrial camera 7. It identifies and extracts the remaining thread data of the well pipe 1 from the images, calculating the remaining thread length S3 = 2.8 mm. Combined with the remaining thread length S2 = 26.4 mm at the start of the dynamic tightening in Step Five, the length of the coupling 2 screwed into the well pipe 1 during the dynamic tightening process is calculated as D2 = S2 - S3 = 26.4 - 2.8 = 23.6 mm. Then, combining the coupling length L = 125 mm from Step Three and the length of the coupling 2 screwed into the well pipe 1 during the pre-tightening stage as D1 = 26.5 mm, the distance from the end face of the well pipe 1 to the center of the coupling 2 can be calculated as J = L / 2 - D1 - D2 = 125 / 2 - 26.5 - 23.6 = 12.4 mm, which is the J-value.

[0077] Step 7: The J-value measuring unit 10 receives a signal indicating whether the tightening has ended through the signal interface unit 8. If not, it continues to execute step 6. If yes, it ends the measurement and records the J-value in step 6, which is the final tightening J-value of the well pipe 1 and coupling 2 = 12.4 mm.

[0078] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. An online measurement method for the J-value of oil well pipe coupling tightening based on image measurement, characterized in that, Includes the following steps: S1. Obtain the current diameter dimensions of the coupling and well casing; S2. At the pre-tightening station, the length value of the end thread of the oil well pipe is acquired and obtained by an industrial camera; S3. Then, the industrial camera is used to collect and obtain the length value of the coupling, the length value of the remaining thread at the end of the oil well pipe, and the length value of the coupling screwed into the oil well pipe. S4. Transport the coupling and the well pipe to the dynamic tightening station; S5. At the tightening station, the length of the remaining thread at the end of the oil well pipe is acquired and obtained by the industrial camera. S6. During the dynamic tightening process, the industrial camera collects and obtains the remaining length value of the end of the oil well pipe. Combined with the remaining length value of the end of the oil well pipe in step S5, the length value of the coupling screwed into the oil well pipe during the dynamic tightening process is calculated. Then, combined with the length value of the coupling in step S3 and the length value of the coupling pre-screwed into the oil well pipe, the J value is calculated. S7. After the tightening is completed, the final J value of the coupling is obtained.

2. The online measurement method for the J-value of oil well pipe coupling tightening based on image measurement according to claim 1, characterized in that, Step S2 specifically includes: At the start of pre-tightening, before the coupling and the well pipe have made contact, the well pipe is fixed by the clamping device. An image of the well pipe is captured by the industrial camera. The end thread data of the well pipe is identified and extracted from the image, and the starting position a and ending position b of the thread, as well as the length S of the thread, are calculated.

3. The online measurement method for the J-value of oil well pipe coupling tightening based on image measurement according to claim 2, characterized in that, Step S3 specifically includes: After pre-tightening is completed and the pre-tightening chuck disengages from the coupling, the industrial camera acquires an image of the coupling and the well pipe being screwed together. From the image, the length value of the coupling and the remaining length value at the end of the well pipe are identified and extracted. The positions d and c of the two ends of the coupling are calculated. Position c is also the intersection position of the coupling and the well pipe and the starting position of the remaining thread of the well pipe. Based on positions d, c, and b, the length value L of the coupling and the remaining thread length value S1 of the well pipe are calculated. Combining the thread length value S, the length value D1 of the coupling screwed into the well pipe is calculated as D1 = S - S1.

4. The online measurement method for the J-value of oil well pipe coupling tightening based on image measurement according to claim 3, characterized in that: Step S5 specifically includes: At the start of the tightening process, after the well pipe is fixed by the moving clamping device, the industrial camera captures an image of the coupling and the well pipe being screwed together. The remaining thread data of the coupling and the well pipe are identified and extracted from the image. The starting position c and the ending position b of the remaining thread of the well pipe are calculated. Based on the positions c and b, the length value S2 of the remaining thread at the start of the tightening process is calculated.

5. The online measurement method for the J-value of oil well pipe coupling tightening based on image measurement according to claim 4, characterized in that: Step S6 specifically includes: During the dynamic tightening process, the dynamic tightening chuck drives the coupling to be continuously screwed into the oil well pipe. The industrial camera captures images of the coupling and the oil well pipe in real time. The remaining thread data of the oil well pipe is identified and extracted from the images. The starting position c and the ending position b of the remaining thread of the oil well pipe are calculated. The length value S3 of the remaining thread is calculated based on the positions c and b. Combined with the length value S2, the length value D2 of the coupling screwed into the oil well pipe during the dynamic tightening process is calculated as D2 = S2 - S3. Then, combined with the length value L of the coupling and the length value D1 of the coupling screwed into the oil well pipe, the J value is calculated as L / 2 - D1 - D2.

6. An online measurement system for the J-value of oil well pipe coupling tightening based on image measurement, characterized in that, include: An industrial camera is installed at the pre-tightening station and the dynamic tightening station to acquire images of the coupling and the oil well pipe in real time; The signal interface unit is used to acquire control signals from the pre-tightening chuck, the moving tightening chuck, the fixed clamping device, and the moving clamping device; A process signal interface unit is used to collect the diameter specification data of the coupling and the well pipe. The J-value measurement unit is used to receive image data, control signals, and diameter specification data transmitted from the industrial camera, the signal interface unit, and the process signal interface unit, and to calculate the J-value. The image-based online measurement system for the tightening J-value of oil well pipe couplings implements the image-based online measurement method for the tightening J-value of oil well pipe couplings as described in any one of claims 1-5.

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