Mechanical monitoring method for buckling state of coiled tubing of horizontal well

Abstract

The invention belongs to the technical field of oil and gas field development, and particularly relates to a buckling state mechanical monitoring method for a horizontal well coiled tubing. A data analysis result is obtained through the six steps of sensor arrangement, data collection, oil pipe excitation, strain change monitoring, data analysis, result evaluation and implementation of corresponding oil pipe maintenance or repair operation, and therefore the buckling state of the oil pipe is accurately evaluated. According to the method, stable and accurate data acquisition and transmission can be ensured, and the buckling state and the mechanical property of the oil pipe are accurately evaluated through an applicable data processing and analysis method, so that abnormal strain change of the oil pipe is found in time, an early warning signal is sent out, and necessary oil pipe maintenance and repair measures are taken; and safe operation and production efficiency of the coiled tubing are ensured, safety risks caused by buckling of the coiled tubing are reduced, and the production efficiency and economic benefits of an oil field are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development technology, specifically relating to a method for monitoring the buckling state of coiled tubing in horizontal wells. Background Technology

[0002] Coiled tubing, compared to conventional threaded tubing, is a high-strength, high-ductility oil and gas pipe with a certain degree of corrosion resistance, with single-strand lengths reaching tens of thousands of meters. The operating environment for coiled tubing is quite harsh, mainly in the following aspects: First, it involves deep insertion depths and heavy loads. Conventional well depths for coiled tubing operations are 3000-6000m, with some reaching nearly 10,000 meters. The tubing string itself can weigh 10-40tf, and the wellhead section bears the greatest axial load. Second, the tubing undergoes plastic deformation during operation. Coiled tubing undergoes multiple plastic deformations during operation, with at least six deformations per well run, typically ranging from 1% to 3%. Each tubing string can be run multiple times within its lifespan, repeatedly used, thus subjecting the string to high-strain, low-cycle fatigue. Third, the tubing string must withstand various loads. During operation, the tubing must withstand high pressures of 10-90MPa, as well as tensile, compressive, torsional, bending, extrusion, and abrasive loads. Fourth, the operating environment is harsh. Downhole tubing is subjected to temperatures of 100-200°C and may contain corrosive media such as H2S and CO2. If acidizing operations are carried out, it will also be subject to corrosion from fresh and residual acid. In order to monitor the condition of coiled tubing at all times, there is an urgent need to find a method to monitor the buckling mechanics of coiled tubing.

[0003] In the prior art, there is a patent with application number 202110825480.5, entitled "A Mechanical Analysis Method for Running Coiled Tubing into a Horizontal Well". This patent considers the wellbore trajectory when establishing the mechanical model of the axial load of the coiled tubing in the horizontal well, which makes it more accurate to determine whether buckling behavior occurs when the coiled tubing is run into the horizontal well, and ensures that the coiled tubing can be successfully run into the horizontal well. However, its calculation process is relatively complicated. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a mechanical monitoring method for the buckling state of coiled tubing in horizontal wells. This method ensures stable and accurate data acquisition and transmission, develops applicable data processing and analysis methods to accurately assess the buckling state and mechanical properties of the tubing, thereby enabling timely detection of abnormal strain changes in the tubing and issuing early warning signals. This reduces the safety risks caused by tubing buckling and improves the efficiency and economic benefits of oilfield production.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for monitoring the buckling state of coiled tubing in horizontal wells includes the following steps: Step 1: Deploy Sensors Deploy sensors to measure strain changes in the oil pipe; Step 2: Data Collection Connect the sensor to the data acquisition system to record the strain data of the tubing; Step 3: Tubing stimulation; Excitement is achieved by applying external force or pressure to the oil pipe; Step 4: Monitor strain changes Data is collected, recorded, and monitored to track strain changes in the tubing. Step 5: Data Analysis; Mathematical models or software tools are used to interpret and analyze the data in order to determine the buckling state and mechanical properties of the tubing. Step Six: Evaluate the results and implement appropriate maintenance or repair operations on the tubing. Based on the data analysis results from step five, assess the buckling condition of the tubing and take necessary maintenance or repair measures.

[0006] In step one, the sensor is placed on the surface or inside the continuous tubing; the sensor is fixed to the tubing by means of a patch or clamp and connected to the data acquisition system; the data acquisition system is a computer or data logger used to collect and store sensor data in real time.

[0007] The specific method for exciting the oil pipe in step three is to apply external force or pressure to the oil pipe by using a hydraulic system or mechanical device.

[0008] The monitoring of strain change in step four involves monitoring the changes in length, shape, or volume of the coiled tubing when it is subjected to stress or deformation.

[0009] The specific process of data analysis in step five is as follows: Amplitude analysis: By observing the amplitude changes of strain data, it can be determined whether the tubing has buckled; if the strain value exceeds the elastic limit of the tubing, the tubing has buckled or deformed. Trend analysis: By observing the trend changes in strain data, we can understand the deformation of the tubing; if the strain value shows a gradual increase or decrease, the tubing is undergoing continuous buckling or deformation.

[0010] The amplitude analysis method is specifically as follows: Calculate the strain amplitude: For each sampling point, calculate the amplitude of the strain data, i.e., the difference between the maximum and minimum strain values, using the following formula: Amplitude = |Maximum strain value - Minimum strain value| Set a threshold: Based on the design and usage requirements of the pipeline, set a threshold value for the amplitude; Determine the buckling state: Compare the calculated amplitude with a threshold; if the amplitude exceeds the threshold, it is determined that the tubing has buckled or deformed, and the degree of buckling can be assessed based on the magnitude of the amplitude. The trend analysis method is specifically as follows: Data smoothing: The acquired strain data is smoothed to reduce the impact of noise and stray signals; Trend calculation: The trend of the smoothed data is estimated by using linear regression, moving average or multinomial regression methods.

[0011] The trend calculation using the polynomial regression method is as follows: Step 1: Data preprocessing: Preprocess the smoothed data to remove outliers and fill in missing values; Step 2: Polynomial regression fitting: Determine the order of the polynomial and use polynomial regression or least squares method to fit the trend of the data; Step 3: Calculate the trend coefficient: Based on the results of the polynomial regression fitting, calculate the coefficients of each term; Step 4: Trend Assessment Assess the change in trend based on the value of the trend coefficient; Step 5: Calculate the curvature parameters to determine the buckling state and mechanical properties of the tubing.

[0012] The fourth step of trend assessment uses a cubic multinomial regression model. The process involves: by fitting data, the coefficients of the cubic term, quadratic term, and linear term are obtained as a, b, and c, respectively, with a constant term as d; the bending trend of the oil pipe is assessed and judged based on the sign or magnitude of each coefficient and the constant term; the specific methods for assessing and judging the bending trend of the oil pipe include the following four methods: judging based on the sign of the cubic term coefficient a, comparing the signs of coefficients other than the cubic term coefficient and the constant term, comparing the absolute values ​​of coefficients other than the cubic term coefficient and the constant term, and comprehensively comparing coefficients.

[0013] The method for determining the sign of the cubic term coefficient 'a' is as follows: Trend assessment: If coefficient a is greater than 0, the tubing bends show an upward curve trend, indicating that the data is on an upward trend; if coefficient a is less than 0, the tubing bends show a downward curve trend, indicating that the data is on a downward trend; if coefficient a is equal to 0, the tubing bends show a linear trend, indicating that the data remains stable; if the tubing bends gradually increase, the tubing may be undergoing continuous buckling or deformation. Trend judgment: Based on the results of the trend coefficient calculation, determine whether the strain data trend is gradually increasing or gradually decreasing; if the trend is gradually increasing, it indicates that the oil pipe may be undergoing continuous buckling or deformation. The comparison of coefficients other than the cubic term and the sign method of the constant term is as follows: If the coefficients b, c, and d have the same sign and are positive, the tendency of the oil pipe to bend will increase. If the coefficients b, c, and d have the same sign and are negative, the bending trend of the oil pipe shows a decreasing shape; If the signs of coefficients b, c, and d are inconsistent, the bending trend of the oil pipe will show a non-monotonic shape, and there may be fluctuations or inflection points. The method of comparing the absolute values ​​of coefficients other than the coefficient of the cubic term and the constant term is as follows: If the absolute value of coefficient b is greater than the absolute values ​​of coefficients c and d, the change in the bending trend of the oil pipe is determined by the quadratic term, and the oil pipe exhibits a bent shape. If the absolute value of coefficient c is greater than the absolute values ​​of coefficients b and d, the change in the bending trend of the oil pipe is determined by the first term, and the oil pipe exhibits a linear shape. If the absolute value of coefficient d is greater than the absolute values ​​of coefficients b and c, the change in the bending trend of the oil pipe is determined by the constant term, and the oil pipe exhibits a flat shape. The comprehensive comparison coefficient method is as follows: S1: Determine the direction of the oil pipe bending trend, i.e., whether it is increasing or decreasing, based on the sign of the coefficient; S2: Determine the shape of the tubing's bending tendency, i.e., whether it is curved, linear, or flat, based on the absolute value of the coefficient; S3: Based on the results obtained in step five and the tubing bending state determined in S1 and S2, calculate the curvature of the tubing to determine the buckling state and mechanical properties of the tubing. The specific calculation method is as follows: The curve of the oil pipe is represented by the function y=f(x), where x and y represent the coordinate axes of the oil pipe, respectively; The curvature K is calculated using formulas from differential geometry, as follows:

[0014] Where y' and y'' represent the first and second derivatives of the function f(x) respectively, and x' and x'' represent the first and second derivatives of x respectively; Based on the calculated curvature K, the buckling state and mechanical properties of the tubing are determined: the magnitude of curvature K indicates the degree of bending of the tubing. If K < 0.01, the curvature is small; if 0.01 ≤ K < 0.1, the curvature is moderate; if ≥ 0.1, the curvature is large; if the curvature is large and the trend is an upward curve, it indicates that the tubing has upward bending and pressure.

[0015] When evaluating the results of step six and implementing corresponding maintenance or repair operations on the tubing, the methods for implementing corresponding operations for different evaluation results are as follows: 1. When the curvature is small, i.e., curvature K < 0.01, the evaluation result is that the oil pipe is in a straight state and there is no bend; Countermeasures: 1) Monitoring: Continue to monitor the status of the oil pipeline and check regularly for any new changes; 2) Preventive maintenance: Regular preventive maintenance is required to ensure long-term stability; 3) Record: Record the current state as the basis for subsequent comparisons; 2. When the curvature is moderate, i.e., when the curvature K is 0.01≤K<0.1, the evaluation result is that the oil pipe has a certain degree of bending, but the degree of bending is relatively small; Countermeasures: 1) Local inspection: Conduct a detailed inspection of the localized area where bending has occurred to ensure that there is no further deterioration; 2) Adjust the load: Adjust the load on the oil pipe appropriately to reduce the possibility of bending; 3) Strengthen the support: Reinforce the support structure in the bending area to prevent further bending; 4) Regular follow-up checks: Regularly check the status of this area to ensure there are no new changes; 3. When the curvature is large, i.e., curvature K≥0.1, the assessment result is that the oil pipe has upward bending and pressure, and there is a possibility that continuous buckling or deformation is occurring. Countermeasures: 1) Stop immediately: Immediately cease current operations to prevent further damage; 2) Detailed inspection: Conduct a comprehensive inspection to determine the cause and specific location of the bend; 3) Repair or Replace: Based on the inspection results, decide whether to repair the damaged part or replace the oil pipe with a new one; 4) Repair: If the damaged part can be repaired, repair or reinforce it; 5) Replacement: If the damage is too severe to repair, replace the damaged part or the entire oil pipe; 6) Optimize design: Analyze the root cause of the bending and optimize the design or installation method of the oil pipe to prevent similar situations from happening again in the future; 7) Strengthen monitoring: After repair or replacement, strengthen monitoring of the area to ensure safe operation.

[0016] Beneficial effects: (1) This invention involves six steps: deploying sensors, collecting data, stimulating the tubing, monitoring strain changes, analyzing data and evaluating results, and implementing corresponding maintenance or repair operations on the tubing. This allows for the timely detection of abnormal strain changes in the tubing and the issuance of early warning signals, thereby reducing the safety risks caused by tubing buckling and improving the efficiency and economic benefits of oilfield production.

[0017] (2) The present invention deploys sensors on the surface or inside of the continuous tubing; the sensors are fixed on the tubing by means of patches or clamps, ensuring stable and accurate data acquisition and transmission.

[0018] (3) This invention uses the polynomial regression method for trend analysis. It only requires comparing the signs and magnitudes of the coefficients of each polynomial to determine the data trend, which is simple and convenient.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example: Refer to Figure 1 The method for monitoring the buckling state of coiled tubing in a horizontal well, as shown, includes the following steps: Step 1: Deploy Sensors Deploy sensors to measure strain changes in the oil pipe; Step 2: Data Collection Connect the sensor to the data acquisition system to record the strain data of the tubing; Step 3: Tubing stimulation; Excitement is achieved by applying external force or pressure to the oil pipe; Step 4: Monitor strain changes Data is collected, recorded, and monitored to track strain changes in the tubing. Step 5: Data Analysis; Mathematical models or software tools are used to interpret and analyze the data in order to determine the buckling state and mechanical properties of the tubing. Step Six: Evaluate the results and implement appropriate maintenance or repair operations on the tubing. Based on the data analysis results from step five, assess the buckling condition of the tubing and take necessary maintenance or repair measures.

[0024] In practical applications, high-precision, high-sensitivity, and high-reliability strain sensors are selected to ensure stable and accurate data acquisition and transmission. This enables timely detection of abnormal strain changes in the oil pipe and the issuance of early warning signals, thereby reducing the safety risks caused by oil pipe buckling and improving the efficiency and economic benefits of oilfield production.

[0025] In some embodiments, in step one, the sensor is deployed on the surface or inside the continuous tubing; the sensor is fixed to the tubing by means of a patch or clamp and connected to a data acquisition system; the data acquisition system is a computer or data logger used to collect and store sensor data in real time.

[0026] In some embodiments, the specific method for exciting the oil pipe in step three is to apply external force or pressure to the oil pipe using a hydraulic system or mechanical device to simulate the stress conditions under actual working conditions. A hydraulic system or mechanical device can be used to apply the force or pressure.

[0027] In some embodiments, monitoring strain changes in step four involves monitoring changes in the length, shape, or volume of the coiled tubing under stress or deformation. The buckling state of the tubing can be assessed based on the magnitude and trend of the strain changes. The frequency of strain change monitoring can be adjusted as needed; real-time monitoring or periodic data acquisition can be selected. During monitoring, the sensor continuously records the strain values ​​of the tubing and transmits them to the data acquisition system for processing and analysis.

[0028] In some embodiments, step five, data analysis, involves using mathematical models or software tools to interpret and analyze the data in order to determine the buckling state and mechanical properties of the tubing. 1) To evaluate the buckling state and mechanical properties of the tubing, the following mathematical model can be used: Linear regression model: used to analyze the trend of strain data over time and determine whether there is continuous deformation or buckling.

[0029] Fourier Transform: Used to analyze the frequency components in strain data to detect the presence of periodic deformation or vibration.

[0030] Finite Element Analysis (FEA): Used to simulate the deformation of tubing under different load conditions and evaluate its buckling state.

[0031] 2) Software tools used Commonly used software tools include, but are not limited to: MATLAB: Used for data processing and analysis, it can perform signal processing, Fourier transforms, etc.

[0032] ANSYS or ABAQUS: Used for finite element analysis to simulate the mechanical behavior of oil pipes.

[0033] Python (in conjunction with libraries such as NumPy, SciPy, and Pandas): used for writing custom data processing and analysis scripts.

[0034] The specific process is as follows: Amplitude analysis: By observing the amplitude changes of strain data, it can be determined whether the tubing has buckled; if the strain value exceeds the elastic limit of the tubing, then the tubing may have buckled or deformed. Trend analysis: By observing the trend changes in strain data, we can understand the deformation of the tubing; if the strain value shows a gradual increase or decrease, the tubing may be undergoing continuous buckling or deformation.

[0035] The purpose of data analysis is to determine the buckling state of the tubing and assess its impact on the wellbore and oilfield development. Based on the results of the data analysis, necessary measures can be taken to maintain and repair the tubing to ensure the continuity and safety of production.

[0036] Furthermore, the amplitude analysis method specifically includes: Calculate the strain amplitude: For each sampling point, calculate the amplitude of the strain data, i.e., the difference between the maximum and minimum strain values, using the following formula: Amplitude = |Maximum strain value - Minimum strain value| Set a threshold: Based on the design and usage requirements of the pipeline, set a threshold value for the amplitude; Determine the buckling state: Compare the calculated amplitude with a threshold; if the amplitude exceeds the threshold, it is determined that the tubing has buckled or deformed, and the degree of buckling can be assessed based on the magnitude of the amplitude. The purpose of data analysis is to determine the buckling state of the tubing and assess its impact on the wellbore and oilfield development. Based on the results of the data analysis, necessary measures can be taken to maintain and repair the tubing to ensure the continuity and safety of production.

[0037] The trend analysis method is specifically as follows: Data smoothing: Smoothing the acquired strain data to reduce the influence of noise and spurious signals. Common smoothing methods include moving average or low-pass filter.

[0038] Trend calculation: The trend of the smoothed data is estimated by using linear regression, moving average or multinomial regression methods.

[0039] Multinomial regression can fit the non-linear trend of data. The change in trend can be evaluated by calculating the coefficients of the multinomial regression. The specific multinomial regression method is as follows: Step 1: Data preprocessing: Preprocess the smoothed data to remove outliers and fill in missing values; Smoothing: Data can be smoothed using methods such as moving averages and filters (e.g., low-pass filters) to reduce the impact of noise.

[0040] Outlier removal: Identify and remove outliers using statistical methods such as Z-score and IQR.

[0041] Filling missing values: Missing values ​​can be filled using interpolation methods (such as linear interpolation, polynomial interpolation), pre- and post-value filling, etc.

[0042] Step 2: Polynomial regression fitting: Determine the order of the polynomial and use polynomial regression or least squares method to fit the trend of the data; The specific method is as follows: 1. Determine the appropriate polynomial order The following factors need to be considered when choosing an appropriate polynomial order: Data complexity: When data fluctuates significantly and has many inflection points, a higher-order polynomial may be needed for fitting.

[0043] Overfitting risk: Choosing too high an order may lead to overfitting, meaning the model is too complex and fits the training data very well, but performs poorly on new data.

[0044] Residual analysis: By observing the residual plot (the difference between the actual and predicted values), if the residuals are randomly distributed, it indicates a good fit; if there is a clear pattern, the order may need to be adjusted.

[0045] Cross-validation: The cross-validation method is used to evaluate the performance of models of different orders on the test set, and the order with the best performance is selected.

[0046] The specific fitting process is as follows: 1. Choose the order: Assuming the order is chosen to be n, the polynomial form is: .

[0047] 2. Least squares fitting: Solving for coefficients , … , This minimizes the sum of squared residuals.

[0048] 3. Fitting formula:

[0049] Where X is the design matrix, containing all powers of x, and y is the observation vector.

[0050] Step 3: Calculate the trend coefficient: Based on the results of the polynomial regression fitting, calculate the coefficients of each term. , … , ; Step 4: Trend Assessment Based on the value of the trend coefficient, the change in the trend can be assessed; the magnitude and sign of each coefficient can be compared to determine whether the trend is gradually increasing, gradually decreasing, or remaining stable. The specific changes in the assessment trend are as follows: Higher-order coefficient analysis: If higher-order coefficients , ... significantly non-zero values ​​indicate a clear trend in the data.

[0051] Low-order coefficient analysis: Low-order coefficients , It reflects the linear trend and translation of the data.

[0052] Step 5: Calculate the curvature parameters to determine the buckling state and mechanical properties of the tubing. Details are as follows: 1) Calculate curvature parameters The curvature parameter can be determined by calculating the derivative of the polynomial function: First derivative: reflects the rate of change of a trend. ; Second derivative: reflects the accelerating change in trend. ; 2) Determine the buckling state and mechanical properties of the tubing. The sign of the first derivative: If the sign of the first derivative changes (i.e. from positive to negative or from negative to positive), it indicates a turning point in the data, which may suggest local deformation or buckling of the oil pipe.

[0053] The sign of the second derivative: If the sign of the second derivative is positive, it indicates that the data is concave (i.e., the oil pipe tends to bend outward in this section); if the sign of the second derivative is negative, it indicates that the data is convex (i.e., the oil pipe tends to bend inward in this section).

[0054] In some embodiments, the fourth step of trend assessment is performed using a cubic multinomial regression model. The process involves: by fitting data, the coefficients of the cubic term, quadratic term, and linear term are obtained as a, b, and c, respectively, with a constant term as d; the bending trend of the oil pipe is assessed and judged based on the sign or magnitude of each coefficient and the constant term; the specific methods for assessing and judging the bending trend of the oil pipe include the following four methods: judging based on the sign of the cubic term coefficient a, comparing the signs of coefficients other than the cubic term coefficient and the constant term, comparing the absolute values ​​of coefficients other than the cubic term coefficient and the constant term, and comprehensively comparing coefficients.

[0055] The method for determining the sign of the cubic term coefficient 'a' is as follows: Trend assessment: If coefficient a is greater than 0, the tubing bends show an upward curve trend, indicating that the data is on an upward trend; if coefficient a is less than 0, the tubing bends show a downward curve trend, indicating that the data is on a downward trend; if coefficient a is equal to 0, the tubing bends show a linear trend, indicating that the data remains stable; if the tubing bends gradually increase, the tubing may be undergoing continuous buckling or deformation. Trend judgment: Based on the results of the trend coefficient calculation, determine whether the strain data trend is gradually increasing or gradually decreasing; if the trend is gradually increasing, it indicates that the oil pipe may be undergoing continuous buckling or deformation. The comparison of coefficients other than the cubic term and the sign method of the constant term is as follows: If the coefficients b, c, and d have the same sign and are positive, the tendency of the oil pipe to bend will increase. If the coefficients b, c, and d have the same sign and are negative, the bending trend of the oil pipe shows a decreasing shape; If the signs of coefficients b, c, and d are inconsistent, the bending trend of the oil pipe will show a non-monotonic shape, and there may be fluctuations or inflection points. The method of comparing the absolute values ​​of coefficients other than the coefficient of the cubic term and the constant term is as follows: If the absolute value of coefficient b is greater than the absolute values ​​of coefficients c and d, the change in the bending trend of the oil pipe is determined by the quadratic term, and the oil pipe exhibits a bent shape. If the absolute value of coefficient c is greater than the absolute values ​​of coefficients b and d, the change in the bending trend of the oil pipe is determined by the first term, and the oil pipe exhibits a linear shape. If the absolute value of coefficient d is greater than the absolute values ​​of coefficients b and c, the change in the bending trend of the oil pipe is determined by the constant term, and the oil pipe exhibits a flat shape. The comprehensive comparison coefficient method assesses the shape and direction of a trend by comprehensively considering the signs and absolute values ​​of multiple coefficients, as detailed below: S1: Determine the direction of the oil pipe bending trend, i.e., whether it is increasing or decreasing, based on the sign of the coefficient; S2: Determine the shape of the tubing's bending tendency, i.e., whether it is curved, linear, or flat, based on the absolute value of the coefficient; S3: Based on the results obtained in step five and the tubing bending state determined in S1 and S2, calculate the tubing curvature to determine the tubing buckling state and mechanical properties. The specific method for calculating the curvature of the oil pipe is as follows: The curve of the oil pipe is represented by the function y=f(x), where x and y represent the coordinate axes of the oil pipe, respectively; The curvature K is calculated using formulas from differential geometry, as follows:

[0056] Where y' and y'' represent the first and second derivatives of the function f(x) respectively, and x' and x'' represent the first and second derivatives of x respectively; Based on the calculated curvature K, the buckling state and mechanical properties of the tubing are determined: the magnitude of curvature K indicates the degree of bending of the tubing. If K < 0.01, the curvature is small; if 0.01 ≤ K < 0.1, the curvature is moderate; if ≥ 0.1, the curvature is large; if the curvature is large and the trend is an upward curve, it indicates that the degree of bending of the tubing is large, and there may be large stress and deformation.

[0057] The magnitude, direction, and shape of the curvature can be used to assess whether the tubing is in a normal condition, under pressure, or deformed. For example, a large curvature with an upward trend may indicate upward bending and pressure in the tubing.

[0058] In some embodiments, when evaluating the results of step six and implementing corresponding maintenance or repair operations on the tubing, the methods for implementing corresponding operations for different evaluation results are as follows: 1. When the curvature is small, i.e., curvature K < 0.01, the evaluation result is that the oil pipe is in a straight state and there is no bend; Countermeasures: 1) Monitoring: Continue to monitor the status of the oil pipeline and check regularly for any new changes; 2) Preventive maintenance: Regular preventive maintenance is required to ensure long-term stability; 3) Record: Record the current state as the basis for subsequent comparisons; 2. When the curvature is moderate, i.e., when the curvature K is 0.01≤K<0.1, the evaluation result is that the oil pipe has a certain degree of bending, but the degree of bending is relatively small; Countermeasures: 1) Local inspection: Conduct a detailed inspection of the localized area where bending has occurred to ensure that there is no further deterioration; 2) Adjust the load: Adjust the load on the oil pipe appropriately to reduce the possibility of bending; 3) Strengthen the support: Reinforce the support structure in the bending area to prevent further bending; 4) Regular follow-up checks: Regularly check the status of this area to ensure there are no new changes; 3. When the curvature is large, i.e., curvature K≥0.1, the assessment result is that the oil pipe has upward bending and pressure, and there is a possibility that continuous buckling or deformation is occurring.

[0059] Countermeasures: 1) Stop immediately: Immediately cease current operations to prevent further damage; 2) Detailed inspection: Conduct a comprehensive inspection to determine the cause and specific location of the bend; 3) Repair or Replace: Based on the inspection results, decide whether to repair the damaged part or replace the oil pipe with a new one; 4) Repair: If the damaged part can be repaired, repair or reinforce it; 5) Replacement: If the damage is too severe to repair, replace the damaged part or the entire oil pipe; 6) Optimize design: Analyze the root cause of the bending and optimize the design or installation method of the oil pipe to prevent similar situations from happening again in the future; 7) Strengthen monitoring: After repair or replacement, strengthen monitoring of the area to ensure safe operation.

[0060] This invention obtains data analysis results through six steps: deploying sensors, collecting data, stimulating the tubing, monitoring strain changes, analyzing data, evaluating results, and implementing corresponding maintenance or repair operations on the tubing. It assesses the buckling state of the tubing and takes necessary maintenance and repair measures to ensure the safe operation and production efficiency of the coiled tubing.

[0061] Where there is no conflict, those skilled in the art can combine the relevant technical features in the above examples according to the actual situation to achieve the corresponding technical effects. Specific details of the various combinations will not be elaborated here.

[0062] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0063] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0064] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Any simple modifications, equivalent variations, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for monitoring the buckling state of coiled tubing in horizontal wells, characterized in that: Includes the following steps, Step 1: Deploy Sensors Deploy sensors to measure strain changes in the oil pipe; Step 2: Data Collection Connect the sensor to the data acquisition system to record the strain data of the tubing; Step 3: Tubing stimulation; Excitement is achieved by applying external force or pressure to the oil pipe; Step 4: Monitor strain changes Data is collected, recorded, and monitored to track strain changes in the tubing. Step 5: Data Analysis; Mathematical models or software tools are used to interpret and analyze the data in order to determine the buckling state and mechanical properties of the tubing. Step Six: Evaluate the results and implement appropriate maintenance or repair operations on the tubing. Based on the data analysis results from step five, assess the buckling condition of the tubing and take necessary maintenance or repair measures.

2. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 1, characterized in that, In step one, the sensor is placed on the surface or inside the continuous tubing; the sensor is fixed to the tubing by means of a patch or clamp and connected to the data acquisition system; the data acquisition system is a computer or data logger used to collect and store sensor data in real time.

3. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 1, characterized in that, The specific method for exciting the oil pipe in step three is to apply external force or pressure to the oil pipe by using a hydraulic system or mechanical device.

4. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 1, characterized in that, The monitoring of strain change in step four involves monitoring the changes in length, shape, or volume of the coiled tubing when it is subjected to stress or deformation.

5. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 1, characterized in that, The specific process of data analysis in step five is as follows: Amplitude analysis: By observing the amplitude changes of strain data, it can be determined whether the tubing has buckled; if the strain value exceeds the elastic limit of the tubing, the tubing has buckled or deformed. Trend analysis: By observing the trend changes in strain data, we can understand the deformation of the tubing; if the strain value shows a gradual increase or decrease, the tubing is undergoing continuous buckling or deformation.

6. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 5, characterized in that, The amplitude analysis method is specifically as follows: Calculate the strain amplitude: For each sampling point, calculate the amplitude of the strain data, i.e., the difference between the maximum and minimum strain values, using the following formula: Amplitude = |Maximum strain value - Minimum strain value| Set a threshold: Based on the design and usage requirements of the pipeline, set a threshold value for the amplitude; Determine the buckling state: Compare the calculated amplitude with the threshold; If the amplitude exceeds the threshold, it is determined that the tubing has buckled or deformed, and the degree of buckling can be assessed based on the magnitude of the amplitude. The trend analysis method is specifically as follows: Data smoothing: The acquired strain data is smoothed to reduce the impact of noise and stray signals; Trend calculation: The trend of the smoothed data is estimated by using linear regression, moving average or multinomial regression methods.

7. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 6, characterized in that, The specific multinomial regression method is as follows: Step 1: Data preprocessing: Preprocess the smoothed data to remove outliers and fill in missing values; Step 2: Polynomial regression fitting: Given the polynomial order, use polynomial regression or least squares method to fit the trend of the data. Step 3: Calculate the trend coefficient: Based on the results of the polynomial regression fitting, calculate the coefficients of each term; Step 4: Trend Assessment Assess the change in trend based on the value of the trend coefficient; Step 5: Calculate the curvature parameters to determine the buckling state and mechanical properties of the tubing.

8. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 7, characterized in that, The fourth step of trend assessment uses a cubic multinomial regression model. The process involves: by fitting data, the coefficients of the cubic term, quadratic term, and linear term are obtained as a, b, and c, respectively, with a constant term as d; the bending trend of the oil pipe is assessed and judged based on the sign or magnitude of each coefficient and the constant term; the specific methods for assessing and judging the bending trend of the oil pipe include the following four methods: judging based on the sign of the cubic term coefficient a, comparing the signs of coefficients other than the cubic term coefficient and the constant term, comparing the absolute values ​​of coefficients other than the cubic term coefficient and the constant term, and comprehensively comparing coefficients.

9. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 8, characterized in that: The method for determining the sign of the cubic term coefficient 'a' is as follows: Trend assessment: If the coefficient a is greater than 0, the oil pipe bend shows an upward curve trend, indicating that the data is showing an upward trend; if the coefficient a is less than 0, the oil pipe bend shows a downward curve trend, indicating that the data is showing a downward trend. If the coefficient a equals 0, the oil pipe bending trend shows a linear trend, indicating that the data remains stable; If the bending trend of the tubing is gradually increasing, the tubing may be undergoing continuous buckling or deformation. Trend judgment: Based on the results of trend coefficient calculation, determine whether the trend of strain data is gradually increasing or gradually decreasing; If the trend is gradually increasing, it indicates that the tubing may be undergoing continuous buckling or deformation; The comparison of coefficients other than the cubic term and the sign method of the constant term is as follows: If the coefficients b, c, and d have the same sign and are positive, the tendency of the oil pipe to bend will increase. If the coefficients b, c, and d have the same sign and are negative, the bending trend of the oil pipe shows a decreasing shape; If the signs of coefficients b, c, and d are inconsistent, the bending trend of the oil pipe will show a non-monotonic shape, and there may be fluctuations or inflection points. The method of comparing the absolute values ​​of coefficients other than the coefficient of the cubic term and the constant term is as follows: If the absolute value of coefficient b is greater than the absolute values ​​of coefficients c and d, the change in the bending trend of the oil pipe is determined by the quadratic term, and the oil pipe exhibits a bent shape. If the absolute value of coefficient c is greater than the absolute values ​​of coefficients b and d, the change in the bending trend of the oil pipe is determined by the first term, and the oil pipe exhibits a linear shape. If the absolute value of coefficient d is greater than the absolute values ​​of coefficients b and c, the change in the bending trend of the oil pipe is determined by the constant term, and the oil pipe exhibits a flat shape. The comprehensive comparison coefficient method is as follows: S1: Determine the direction of the oil pipe bending trend, i.e., whether it is increasing or decreasing, based on the sign of the coefficient; S2: Determine the shape of the tubing's bending tendency, i.e., whether it is curved, linear, or flat, based on the absolute value of the coefficient; S3: Based on the results obtained in step five and the tubing bending state determined in S1 and S2, calculate the curvature of the tubing to determine the buckling state and mechanical properties of the tubing. The specific calculation method is as follows: The curve of the oil pipe is represented by the function y=f(x), where x and y represent the coordinate axes of the oil pipe, respectively; The curvature K is calculated using formulas from differential geometry, as follows: Where y' and y'' represent the first and second derivatives of the function f(x) respectively, and x' and x'' represent the first and second derivatives of x respectively; Based on the calculated curvature K, the buckling state and mechanical properties of the tubing are determined: the magnitude of curvature K indicates the degree of bending of the tubing. If K < 0.01, the curvature is small; if 0.01 ≤ K < 0.1, the curvature is moderate; if ≥ 0.1, the curvature is large; if the curvature is large and the trend is an upward curve, it indicates that the tubing has upward bending and pressure.

10. The method for monitoring the buckling state of coiled tubing in a horizontal well as described in claim 1, characterized in that, When evaluating the results of step six and implementing corresponding maintenance or repair operations on the tubing, the methods for implementing corresponding operations for different evaluation results are as follows: When the curvature is small, i.e., curvature K < 0.01, the evaluation result is that the oil pipe is in a straight state and there is no bend; Countermeasures: Monitoring: Continue to monitor the status of the oil pipeline and check regularly for any new changes; Preventive maintenance: Regular preventive maintenance is required to ensure long-term stability; Record: Record the current state as the basis for subsequent comparisons; When the curvature is moderate, i.e., when the curvature K is 0.01≤K<0.1, the evaluation result is that the oil pipe has a certain degree of bending, but the degree of bending is relatively small; Countermeasures: Local inspection: Conduct a detailed inspection of the localized area where bending has occurred to ensure there is no further deterioration; Adjust the load: Adjust the load on the oil pipe appropriately to reduce the possibility of bending; Strengthen the support: Reinforce the support structure in the bending area to prevent further bending; Regular check-ups: Regularly check the status of this area to ensure there are no new changes; When the curvature is large, i.e., curvature K≥0.1, the assessment result is that the oil pipe has upward bending and pressure, and there is a possibility that continuous buckling or deformation is occurring. Countermeasures: Immediate shutdown: Immediately stop the current operation to avoid further damage; Detailed inspection: Conduct a comprehensive inspection to determine the cause and specific location of the bend; Repair or Replacement: Based on the inspection results, decide whether to repair the damaged part or replace the oil pipe with a new one; Repair: If the damaged part can be repaired, repair or reinforce it; Replacement: If the damage is too severe to repair, replace the damaged part or the entire oil pipe; Optimize the design: Analyze the root cause of the bending and optimize the design or installation of the oil pipe to prevent similar situations from happening again in the future; Enhanced monitoring: After repair or replacement, enhanced monitoring of the area is required to ensure safe operation.

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