Method for verifying leakage point of water injection well sleeve by measuring well temperature in oil pipe

Abstract

The invention relates to the technical field of water injection well sleeve leakage point detection, and discloses a method for verifying a water injection well sleeve leakage point through well temperature measurement in an oil pipe, and the method comprises the following steps: 1, stopping water injection operation, putting a well temperature test instrument into a well, and recording a well temperature change curve from the bottom of the well to the mouth of the well; 2, prepared 20-60 cubic meters of ground clean water is injected into the casing pipe, and temperature conduction is waited for 15-55 minutes; thirdly, the well temperature testing instrument is put into the well again, and a well temperature change curve from the well bottom to the well mouth is recorded; fourthly, the two curves are compared, the positions of the sleeve leakage points are determined, temperature abnormal areas can appear above the positions corresponding to the sleeve leakage points, and the positions below the sleeve leakage points basically coincide with one another. According to the invention, the temperature change can be measured by tripping in the well temperature testing instrument twice. The casing leakage position can be determined by comparing the temperature change in the oil pipe before clear water is injected into the casing.

Description

Technical Field

[0001] This invention relates to the field of water injection well casing leakage detection technology, and in particular to a method for verifying water injection well casing leakage by logging well temperature inside the tubing. Background Technology

[0002] As oilfield development progresses, casing leakage in water injection wells has become increasingly prominent. During water injection well production, if a rapid drop in injection pressure, a sudden increase in injection volume, or even surface backflow occurs, casing leakage is suspected, necessitating casing verification to pinpoint the leakage location. Currently, common methods for verifying casing condition include running a well temperature instrument inside the casing to test for leakage, or directly removing the downhole tubing and running a flow meter to locate the leak. The first method requires specialized wellhead equipment for instrument insertion, while the second requires workover equipment and coordinated operations, making it too expensive and time-consuming. Even after testing or workover, if no casing leakage is found, significant manpower and financial resources are wasted. Failure to verify casing leakage will hinder subsequent water injection operations and hinder effective water injection.

[0003] A search revealed a Chinese invention patent application (CN202010906326.6) that discloses a method for identifying leaks in wells with casing damage. This method involves artificially generating fluid flow within the wellbore and using noise logging instruments to measure the amplitude and frequency of noise generated when the fluid flows through the cement sheath or formation outside the casing to determine the location of the fluid source. This method is further enhanced by combining well temperature and flow rate data to improve the accuracy and success rate of leak and cross-contamination detection. However, this prior art requires coordinated operational procedures and the deployment of specialized instruments within the well for testing.

[0004] A search revealed that Chinese invention patent application number 201910595561.3 discloses a method for processing MIT-MTT test data of casing damage in water injection wells, solving the problem of the inability to quantitatively compare casing damage conditions of different water injection wells at different times within a block. First, the data describing the corrosion of the casing damage in each well is normalized. Based on the normalization results, different weight values ​​are assigned to the percentage of casing with different corrosion degrees, and adjustments are made according to the number of perforated pipe segments in the non-perforated section. The weighted sum of the corrosion degree of casing damage in each water injection well is then calculated. Next, grey relational analysis is used to calculate the relative grey relational degree between the weighted sum of the corrosion degree of the water injection well casing damage and the collected productive factors and environmental factors affecting water injection well corrosion, determining the significant influencing factors and their ranking. Finally, the corrosion mechanism of casing damage within the research block is clarified, fully utilizing the relevant information implicit in the water injection well casing damage test data, thus expanding the engineering application value of the water injection well casing damage test project. This comparative document analyzes a series of parameters within the casing through operational procedures to identify the factors affecting the casing and determine its overall condition. It provides a comprehensive analysis of the entire casing. This comparative document requires operational procedures, relevant testing equipment, and significant manpower for the analytical work.

[0005] A search revealed Chinese utility model patent application number 201921987749.4, which discloses an oil casing connector for leak detection tubing. The connector includes a lower connector, a central tube axially movable within the lower connector, and a connecting outer tube positioned between the lower connector and the central tube. The connecting outer tube has an external flow hole, and the central tube has an internal flow hole at its position where it is fitted onto the lower connector. The internal flow hole moves out of the lower connector and communicates with the external flow hole when the central tube is lifted. This utility model offers advantages such as convenient packer unsealing, improved packer lifespan, and ease of construction. The leak detection device described in this prior art requires construction work to complete the leak detection.

[0006] Therefore, there is an urgent need on-site for a method to verify leakage points in water well casing that requires no operational coordination, is simple to operate, and does not require the addition of special wellhead devices. Therefore, this invention proposes a method for verifying leakage points in water injection well casing using tubing-based well temperature logging. Summary of the Invention

[0007] The present invention mainly addresses the technical problems existing in the prior art and provides a method for verifying leakage points in water injection well casings by logging well temperature inside the tubing.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a method for verifying leakage points in a water injection well casing using tubing logging temperature, comprising the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument from the wellhead into the water injection well tubing to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 20-30 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 20 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. An abnormal temperature zone will appear above the location of the leak, while the location below the leak point will basically overlap.

[0009] Preferably, the first step involves stopping the water injection operation and lowering the test end of the well temperature testing instrument into the well. The measurement parameters of the well temperature testing instrument include magnetic positioning, natural gamma, and well temperature. At this time, the well temperature change curve from the bottom of the well to the wellhead is recorded to ensure that the water injection operation is stopped and the well temperature test is carried out under safe operating conditions. The testing instrument is calibrated before measurement to ensure the accuracy and reliability of the measurement.

[0010] Preferably, in the first step, parameters of well depth, well diameter, and geological conditions are collected before temperature measurement. Based on the collected parameters, the well temperature testing instrument is lowered into the well through the test cable from the water injection well tubing. When lowering the testing end of the instrument, it is moved at a constant speed and the lowering depth is ensured to be 30m above the upper boundary of the water injection layer.

[0011] Preferably, in the first step, the well temperature testing instrument is lowered into the well via a test cable from inside the injection well tubing, and the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature are measured.

[0012] As a preferred option, the second step involves injecting 20-60 cubic meters of prepared surface water into the casing and waiting for temperature conduction for 15-55 minutes. During this step, the quality and purity of the surface water must be strictly ensured to avoid pollution of the downhole environment. During the water injection process, the injection pressure is controlled according to the pressure resistance of the wellhead and casing to ensure maximum injection volume, and the injection completion time does not exceed 60 minutes.

[0013] Preferably, the third step involves lowering the well temperature testing instrument back into the well and recording the well temperature change curve from the bottom of the well to the wellhead. In this step, the test cable of the well temperature testing instrument is lowered from the water injection well tubing into the well. When lowering the testing instrument, the instrument is moved at a constant speed and the lowering depth is ensured to be 30m above the upper boundary of the water injection layer.

[0014] Preferably, in the third step, when measuring after water injection, a test cable is lowered into the well from inside the water injection well tubing, and the first measurement position after water injection is the same as the first measurement position before water injection. After the measurement, the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature are recorded.

[0015] As a preferred option, the fourth step involves comparing the two curves to determine the location of the leak point. A temperature anomaly zone will appear above the location corresponding to the leak point, while the locations below it will basically overlap. In this step, the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature measured before water injection are compared with the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature measured after water injection.

[0016] Preferably, in the fourth step, by comparing the measurement data before and after water injection, the point where the temperature overlaps can be determined quickly and efficiently to identify the leak point in the casing.

[0017] Preferably, the determination of the temperature overlap point in the fourth step adopts a comprehensive comparative analysis method, which includes comparing the temperature change rate before and after water injection and calculating in combination with formation physical parameters to determine the accuracy of the casing leak location. Beneficial effects

[0018] This invention provides a method for verifying leakage points in water injection well casings using in-tubing logging temperature. It has the following beneficial effects: The method for verifying leakage points in water injection well casings by logging well temperature inside the tubing is based on the principle of heat conduction and formation temperature.

[0019] Because tubing is made of steel, it is an excellent conductor of heat, allowing the casing annulus temperature to be transferred to the tubing and the injected water within it. During normal water injection, the temperature of the injected water in the tubing reflects the formation temperature. After the well is shut down and a measuring device is installed, the measured curve becomes the baseline curve, displaying the formation temperature. When the casing is undamaged, the injected water causes a temperature drop, and after shutting down the well, a well temperature tester should be installed, showing a well temperature curve significantly lower than the baseline curve. However, when the casing is damaged, the injected water is entirely drawn into the leak point. Therefore, the measured temperature above the leak point is the temperature after the water has cooled, while the measured temperature below the leak point remains the formation temperature. The measurement result will show a curve that intersects with or approaches the baseline curve at its inflection point. Therefore, the temperature change can be measured by installing the well temperature tester twice. By comparing the temperature change in the tubing before and after water injection, the location of the leak can be determined.

[0020] This method for verifying leakage points in water injection well casings by logging well temperature inside the tubing eliminates the need for special wellhead devices and tubing string extraction, and requires no operational coordination. It can quickly and efficiently verify casing leakage.

[0021] 3. This method for verifying the leakage point of a water injection well casing by logging the well temperature inside the tubing does not require running the testing instrument into the casing, thus avoiding the problem of the instrument getting stuck and unable to achieve the testing purpose; it does not require changing the wellhead structure to adapt to running the instrument into the casing, thus avoiding the cost of modifying the wellhead for operation; the temperature change at the leakage point can be measured from inside the tubing by the principle of temperature conduction, and the leakage point can be determined by the temperature change. Attached Figure Description

[0022] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0023] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0024] Figure 1 This is a temperature test diagram before and after water injection according to the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] In the description of this invention, 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, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention 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, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] A method for verifying leakage points in a water injection well casing using tubing logging temperature includes the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument into the well to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 20-60 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 15-55 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap.

[0029] In the first step: stop the water injection operation and lower the test end of the well temperature testing instrument into the well. The measurement parameters of the well temperature testing instrument include magnetic positioning, natural gamma, and well temperature. At this time, record the well temperature change curve from the bottom of the well to the wellhead. Ensure that the water injection operation is stopped and the well temperature test is carried out under safe operating conditions. Before the measurement, the testing instrument is calibrated to ensure the accuracy and reliability of the measurement.

[0030] In the first step, before temperature measurement, parameters of well depth, well diameter and geological conditions are collected. Based on the collected parameters, the well temperature testing instrument is lowered into the well from the water injection well tubing through the testing cable. When the testing end of the instrument can be removed, it is moved at a constant speed and the lowering depth is ensured to be 30m above the upper boundary of the water injection layer.

[0031] In the first step, the well temperature testing instrument is lowered into the well via a test cable from inside the water injection well tubing, and the corresponding data for the three parameters of magnetic positioning, natural gamma, and temperature are measured.

[0032] Step 2: Inject 20-30 cubic meters of prepared surface water into the casing and wait for the temperature to conduct for 20 minutes. In this step, the quality and purity of the surface water must be strictly ensured to avoid pollution of the downhole environment. During the water injection process, the injection pressure should be controlled according to the pressure resistance of the wellhead and casing to ensure maximum injection volume and the injection completion time should not exceed 60 minutes.

[0033] In the third step: the well temperature testing instrument is lowered into the well again to record the well temperature change curve from the bottom of the well to the wellhead. In this step, the test cable of the well temperature testing instrument is lowered from the water injection well tubing into the well. When lowering the testing instrument, the instrument is moved at a constant speed and the lowering depth is ensured to be 30m above the upper limit of the water injection layer.

[0034] In the third step, after water injection, the test cable is lowered into the well through the water injection well tubing, ensuring that the first measurement position after water injection is the same as the first measurement position before water injection. After the measurement, the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature are recorded.

[0035] In the fourth step, the two curves are compared to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap. In this step, the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature measured before water injection are compared with the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature measured after water injection.

[0036] In the fourth step, by comparing the measurement data before and after water injection, the point where the temperature overlaps can be determined quickly and efficiently to identify the leak point in the casing.

[0037] The determination of the temperature overlap point in the fourth step adopts a comprehensive comparative analysis method, which includes comparing the temperature change rate before and after water injection and calculating in combination with formation physical parameters to determine the accuracy of the casing leak location. Example 1

[0038] A method for verifying leakage points in a water injection well casing using tubing logging temperature includes the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument into the well to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 20 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 15 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap.

[0039] The specific test results are shown in Table 1:

[0040] Table 1. Well temperature recording parameters at different depths Example 2

[0041] A method for verifying leakage points in a water injection well casing using tubing logging temperature includes the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument into the well to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 30 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 25 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap.

[0042] The specific test results are shown in Table 2:

[0043] Table 2. Well temperature recording parameters at different depths Example 3

[0044] A method for verifying leakage points in a water injection well casing using tubing logging temperature includes the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument into the well to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 40 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 35 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap.

[0045] The specific test results are shown in Table 3:

[0046] Table 3. Well temperature record parameters at different depths Example 4

[0047] A method for verifying leakage points in a water injection well casing using tubing logging temperature includes the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument into the well to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 50 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 45 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap.

[0048] The specific test results are shown in Table 4:

[0049] Table 4. Well temperature recording parameters at different depths Example 5

[0050] A method for verifying leakage points in a water injection well casing using tubing logging temperature includes the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument into the well to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 60 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 55 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap.

[0051] The specific test results are shown in Table 5:

[0052] Table 5. Well temperature recording parameters at different depths Example 6

[0053] A method for verifying leakage points in a water injection well casing using tubing logging temperature includes the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument into the well to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 60 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 15 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap.

[0054] The specific test results are shown in Table 6:

[0055] Table 6. Well temperature recording parameters at different depths In this method, because the tubing is made of steel, it is an excellent conductor of heat. The temperature of the casing annulus can be transferred to the tubing and then to the injected water inside the tubing. When the injected water reaches the leak point, it is completely drawn into the leak point. From the wellhead to the leak point, the well is filled with injected water, causing a temperature drop, which is then transferred through the tubing into the tubing. Below the leak point, the formation temperature remains unchanged. The temperature change can be measured using a temperature testing instrument after two well runs. By comparing the temperature change inside the tubing before and after water injection, the location of the leak can be determined.

[0056] This method eliminates the need for instruments to be run into the casing to test the well temperature, thus avoiding the problem of instruments getting stuck and failing to achieve the testing objective. It also eliminates the need to change the wellhead structure to accommodate instruments running into the casing, thus avoiding the cost of modifying the wellhead for operation. The method allows for the measurement of temperature changes at the casing leakage location directly from inside the tubing using the principle of temperature conduction, enabling accurate determination of the casing leakage location using temperature changes.

[0057] Example 1: Inspection of deep water injection wells Scenario description: A deep water injection well located in an oil field, with a total depth of 1450 meters, has recently experienced abnormal water injection pressure, suspected to be caused by casing leakage.

[0058] Operating steps: Stop water injection: First, turn off the water injection pump to ensure the dynamic stability of the water in the well.

[0059] Lowering the temperature measuring instrument: Carrying a high-precision well temperature testing instrument, slowly lower it from the wellhead to the bottom of the well to record well temperature data in real time and generate an initial temperature curve.

[0060] Fill with water and wait: Inject 40 cubic meters of clean water into the casing and let it stand for 45 minutes to allow the water temperature to reach thermal equilibrium with the surrounding rock temperature.

[0061] Second temperature measurement: Repeat the first step, lower the well temperature testing instrument to the bottom of the well again, and record the new well temperature change curve.

[0062] Data analysis: Comparing the two well temperature curves, a significant abnormal increase in temperature was observed at 900 meters, which contrasted with the surrounding area, leading to a diagnosis of a casing leak.

[0063] Example 2: Shallow water injection well inspection Scenario description: A shallow water injection well with a total depth of 200 meters has recently experienced a sharp decline in water injection efficiency, raising suspicion of a leak.

[0064] Operating steps: Stop water injection and record the initial temperature: Similarly, first stop all water injection operations and use a well temperature testing instrument to record the temperature step by step from the bottom of the well to the wellhead.

[0065] Pour in clean water and wait: Pour 20 cubic meters of surface water into the well and let it stand still for 15 minutes to allow the temperature to stabilize.

[0066] Measure the well temperature again: Record the well temperature again using the same instrument to form a second well temperature curve.

[0067] Analysis and location: By comparing the two well temperature curves, it was found that the temperature suddenly rose at 180 meters, which confirmed that this was a leak point.

[0068] Example 3: Locating the Leakage Point in a Mid-Level Injection Well Scenario description: A water injection well in an oil field, 750 meters deep, is being tested to accurately locate potential leaks.

[0069] Operating steps: Well temperature record: The first recording of the temperature profile from the bottom of the well to the wellhead.

[0070] Water injection treatment: Inject 30 cubic meters of clean water into the casing and wait for 30 minutes, allowing the temperature to be evenly distributed in the well.

[0071] Repeat temperature measurement: Lower the testing instrument again and record the new temperature curve.

[0072] Analysis of the leak point: By comparing the two curves, a temperature anomaly was found at 650 meters. This significant temperature change confirmed the leak point.

[0073] Example 4: Multi-point leakage detection Scenario description: A water injection well in an oil field, 1200 meters deep, is suspected of having multiple leaks.

[0074] Operating steps: Initial well temperature record: Record the complete initial well temperature curve.

[0075] Inject large amounts of water and wait: Inject 50 cubic meters of clean water into the casing and wait 50 minutes.

[0076] Record the well temperature again: Lower the well temperature testing instrument and collect the well temperature data a second time.

[0077] Analysis and location: The well temperature curves show temperature anomalies at both the 300-meter and 1100-meter locations, indicating that there are leaks at both of these locations.

[0078] Example 5: Abnormal Temperature Analysis Scenario description: A water injection well located in the Southwest Oilfield, with a total depth of 1300 meters, undergoes regular leak detection.

[0079] Operating steps: Record the temperature profile from bottom to top of the well: Use a high-precision well temperature testing instrument to record the original temperature profile from bottom to top of the well.

[0080] Inject the maximum amount of clean water: Inject 60 cubic meters of clean water into the well and wait 55 minutes to achieve the optimal temperature distribution.

[0081] Second temperature measurement: Repeat the well temperature recording process to obtain a second temperature curve.

[0082] Leak location: Comparison of two temperature curves showed a significant temperature anomaly at a depth of 1200 meters, confirming the location as the leak point.

[0083] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for verifying leakage points in a water injection well casing using tubing logging temperature, characterized in that: Includes the following steps: Step 1: Stop the water injection operation and lower the well temperature testing instrument into the well to record the well temperature change curve from the bottom of the well to the wellhead; Step 2: Pour 20-60 cubic meters of clean water into the sleeve and wait for the temperature to conduct for 15-55 minutes; Step 3: Lower the well temperature testing instrument back into the well and record the well temperature change curve from the bottom of the well to the wellhead; Step 4: Compare the two curves to determine the location of the leak. A temperature anomaly zone will appear above the location corresponding to the leak, while the location below it will basically overlap.

2. The method for verifying leakage points in injection well casings by logging temperature inside the tubing according to claim 1, characterized in that: The first step is to stop the water injection operation and lower the test end of the well temperature testing instrument into the well. The measurement parameters of the well temperature testing instrument include magnetic positioning, natural gamma, and well temperature. At this time, the well temperature change curve from the bottom of the well to the wellhead is recorded. Ensure that the water injection operation is stopped and the well temperature test is carried out under safe operating conditions. Before the measurement, the testing instrument is calibrated to ensure the accuracy and reliability of the measurement.

3. The method for verifying leakage points in injection well casings by logging well temperature inside the tubing according to claim 2, characterized in that: In the first step, before temperature measurement, parameters of well depth, well diameter and geological conditions are collected. Based on the collected parameters, the well temperature testing instrument is lowered into the well from the water injection well tubing through the testing cable. When lowering the testing instrument, the instrument is moved at a constant speed and the lowering depth is ensured to be 30m above the upper boundary of the water injection layer.

4. The method for verifying leakage points in a water injection well casing using tubing logging temperature according to claim 3, characterized in that: In the first step, during the measurement, a test cable is lowered from inside the water injection well tubing into the well, and the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature are measured.

5. The method for verifying leakage points in a water injection well casing using tubing logging temperature according to claim 1, characterized in that: The second step: Inject 20-30 cubic meters of prepared surface water into the casing and wait for the temperature to conduct for 20 minutes. In this step, the quality and purity of the surface water must be strictly ensured to avoid pollution of the downhole environment. During the water injection process, the injection pressure should be controlled according to the pressure resistance of the wellhead and casing to ensure the maximum injection volume and the injection completion time should not exceed 60 minutes.

6. The method for verifying leakage points in a water injection well casing using tubing logging temperature according to claim 5, characterized in that: The third step involves lowering the well temperature testing instrument back into the well and recording the well temperature change curve from the bottom of the well to the wellhead. In this step, the well temperature testing instrument is lowered into the well from the water injection well tubing via a testing cable. When lowering the testing end of the instrument, it is moved at a constant speed and the lowering depth is ensured to be 30m above the upper boundary of the water injection layer.

7. The method for verifying leakage points in a water injection well casing using tubing logging temperature according to claim 6, characterized in that: In the third step, when measuring after water injection, the well temperature testing instrument is lowered into the well through the water injection well tubing via a testing cable, ensuring that the first measurement position after water injection is the same as the first measurement position before water injection. After measurement, the corresponding data of the three parameters of magnetic positioning, natural gamma, and temperature are recorded.

8. The method for verifying leakage points in injection well casings by logging well temperature inside the tubing according to claim 1, characterized in that: The fourth step involves comparing the two curves to determine the location of the leak. A temperature anomaly zone will appear above the leak point, while the area below it will largely overlap. In this step, the data of the magnetic positioning, natural gamma, and temperature parameters measured before water injection will be compared with the data of the same parameters measured after water injection.

9. The method for verifying leakage points in a water injection well casing using tubing logging temperature according to claim 8, characterized in that: In the fourth step, by comparing the measurement data before and after water injection, the point where the temperature overlaps can be determined, thus quickly and efficiently identifying the leak point in the casing.

10. The method for verifying leakage points in a water injection well casing using tubing logging temperature according to claim 9, characterized in that: The determination of the temperature overlap point in the fourth step adopts a comprehensive comparison method, which includes comparing the temperature change rate before and after water injection and calculating in combination with formation physical parameters to determine the accuracy of the casing leak location.

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