Method for detecting leakage of microgap between sleeve and cement sheath of geological carbon dioxide storage well

Abstract

The method for detecting the leakage of the microgap between the casing pipe and the cement sheath of the carbon dioxide geological storage well comprises the following steps: S1, arranging a plurality of temperature sensors at a plurality of positions on the inner wall surface of the casing pipe in a one-to-one correspondence manner, so that the plurality of temperature sensors respectively monitor the temperatures of the plurality of positions on the inner wall surface of the casing pipe; s2, tracer gas is injected into the bottom of the annular cavity so as to replace original gas in the annular cavity; s3, the sleeve is used for extracting tracer gas outwards, and temperature change values monitored by the multiple temperature sensors are collected at the same time; and S4, according to the temperature change values monitored by the plurality of temperature sensors, the leakage conditions of the plurality of positions of the sleeve are judged. Therefore, according to the leakage detection method for the microgap between the sleeve and the cement sheath of the carbon dioxide geological storage well, whether the sleeve leaks or not and the position of a leakage point can be conveniently detected.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide storage technology, specifically to a method for detecting micro-gap leakage between the casing and cement sheath in a carbon dioxide geological storage well. Background Technology

[0002] In CO2 geological storage wells, micro-gaps may form between the casing and the cement sheath, leading to leakage of the storage fluid. Existing detection technologies include: annular pressure monitoring, which monitors changes in annular pressure to detect leaks, but has low sensitivity and cannot pinpoint the leak location; acoustic detection, which emits sound waves to detect defects in the cement sheath, but the reflected signal from micro-gaps is weak; and distributed temperature sensing (DTS), which requires pre-embedded optical fibers, is costly, and struggles to distinguish between micro-leaks and temperature noise. These methods cannot pinpoint the leak point; the pressure / temperature method only provides an overall leak signal and cannot determine the depth and location of micro-gaps; they lack sensitivity due to low seepage rates in micro-gaps and difficulty in detecting pressure accumulation effects; and they have poor anti-interference capabilities, as wellbore temperature fluctuations and formation stress changes easily trigger false alarms. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for detecting micro-gap leakage between the casing and cement sheath in carbon dioxide geological storage wells.

[0004] The present invention discloses a method for detecting micro-gap leakage between the casing and cement sheath in a carbon dioxide geological storage well. The carbon dioxide geological storage well includes a casing, a wellbore, and a cement sheath, wherein the cement sheath is located within the annular cavity between the casing and the wellbore. The method comprises the following steps:

[0005] S1. Multiple temperature sensors are installed at multiple locations on the inner wall of the sleeve, so that the multiple temperature sensors can monitor the temperature at multiple locations on the inner wall of the sleeve respectively.

[0006] S2. Inject tracer gas into the bottom of the annular cavity to replace the original gas in the annular cavity, wherein the thermal conductivity of the tracer gas is greater than that of air so that the heat carried away by the tracer gas flowing through the sleeve leak point is greater than the heat carried away by the air flowing through the sleeve leak point.

[0007] S3. Use the sleeve to draw tracer gas outward and simultaneously collect temperature change values ​​monitored by multiple temperature sensors;

[0008] S4. Determine the leakage status at multiple locations of the bushing based on the temperature change values ​​monitored by the multiple temperature sensors.

[0009] Therefore, the method for detecting micro-gap leakage between the casing and cement sheath in a carbon dioxide geological storage well according to embodiments of the present invention facilitates the detection of whether the casing is leaking and the location of the leakage point.

[0010] In some embodiments, in step S1, at least some of the plurality of temperature sensors are spaced apart in the vertical direction.

[0011] In some embodiments, in step S1, the distance between two adjacent temperature sensors in the vertical direction is less than or equal to 20 meters, and at least some of the multiple temperature sensors are arranged at equal intervals in the vertical direction.

[0012] In some embodiments, the carbon dioxide geological storage well includes an intermediate tube body located within the casing, and an annular top valve is provided at the top of the casing for closing the annular opening between the upper opening of the casing and the intermediate tube body.

[0013] In step S2, the annular top valve is closed, and tracer gas is injected into the bottom of the annular cavity using the intermediate tube.

[0014] In step S3, the annular top valve is opened, and air is drawn outward through the annular opening of the sleeve, causing the pressure in the cavity between the sleeve and the intermediate tube to drop to a negative pressure.

[0015] In some embodiments, in step S3, the gas flow rate pumped outward using the annular opening of the sleeve is greater than or equal to 0.1 L / min and less than or equal to 1 L / min.

[0016] In some embodiments, in step S4, leakage at multiple locations of the bushing is determined based on at least one of the temperature decrease value and the temperature decrease rate monitored by the plurality of temperature sensors.

[0017] In some embodiments, in step S4, if the temperature drop value monitored by the temperature sensor is greater than or equal to a first preset value, and / or the temperature drop rate monitored by the temperature sensor is greater than or equal to a second preset value, then the location of the sleeve where the temperature sensor is located is determined to be a leak location.

[0018] In some embodiments, in step S4, after determining that the sleeve has leaked based on the temperature change values ​​monitored by the multiple temperature sensors, the pumping of air outward from the annular opening of the sleeve is stopped and the top valve of the annulus is closed. The pressure rise in the cavity between the sleeve and the intermediate tube is monitored in order to determine the leakage of the sleeve.

[0019] In some embodiments, in step S4, after stopping the evacuation from the annular opening of the casing and closing the annular top valve, if the pressure rise rate of the cavity between the casing and the intermediate tube is less than 0.01 MPa / min, the leak point of the casing is determined to be a micro-gap leak; if the pressure rise rate of the cavity between the casing and the intermediate tube is greater than or equal to 0.01 MPa / min, the leak point of the casing is determined to be a large crack.

[0020] In some embodiments, the tracer gas is helium or hydrogen. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a carbon dioxide geological storage well according to an embodiment of the present invention.

[0022] Figure 2 This is a top view of the sleeve and cement ring according to an embodiment of the present invention.

[0023] Reference numerals: 1. Casing, 2. Wellbore, 3. Cement sheath, 4. Annular cavity, 5. Intermediate pipe body, 6. Annular top valve, 7. Casing annular opening. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0025] The following describes a method for detecting micro-gap leakage in the casing and cement sheath of a carbon dioxide geological storage well, according to an embodiment of the present invention, with reference to the accompanying drawings. Figure 1 and Figure 2 As shown, a carbon dioxide geological storage well includes a casing 1, a wellbore 2, and a cement sheath 3. The cement sheath 3 is located within the annular cavity 4 between the casing 1 and the wellbore 2. After prolonged expansion and contraction, cementation failure can occur, resulting in micro-gaps between the cement sheath 3 and the casing 1, leading to leakage points at some locations on the casing. The carbon dioxide geological storage well includes an intermediate tube 5 located within the casing 1. The upper part of the intermediate tube 5 extends beyond the upper opening of the casing 1, and the bottom of the intermediate tube 5 is located at the bottom of the casing 1. An annular top valve 6 is provided at the top of the casing 1, which is used to seal the annular opening 7 between the upper opening of the casing 1 and the intermediate tube 5.

[0026] The method for detecting micro-gap leakage between the casing and cement sheath in a carbon dioxide geological storage well according to an embodiment of the present invention includes the following steps:

[0027] S1. Multiple temperature sensors are installed at corresponding locations on the inner wall of the sleeve 1, so that the multiple temperature sensors can monitor the temperature at multiple locations on the inner wall of the sleeve 1 respectively. Specifically, the temperature sensors are used to monitor the temperature at their respective locations, thereby observing and recording the temperature change values ​​at the locations of the temperature sensors.

[0028] In some embodiments, in step S1, at least some of the plurality of temperature sensors are spaced apart in the vertical direction. This is used to monitor the temperature (change value) at multiple locations in the vertical direction of the sleeve 1. For example, at least some of the plurality of temperature sensors are spaced apart in the vertical direction, and at least some of the plurality of temperature sensors are spaced apart in the circumferential direction of the sleeve.

[0029] In some embodiments, in step S1, the distance between two adjacent temperature sensors in the vertical direction is less than or equal to 20 meters, and at least some of the multiple temperature sensors are arranged at equal intervals in the vertical direction. For example, the distance between two adjacent temperature sensors in the vertical direction is 5 meters or 10 meters.

[0030] S2. Inject tracer gas into the bottom of the annular cavity 4 to displace the existing gas within the annular cavity 4. Specifically, in step S2, close the top valve 6 of the annular cavity, and inject tracer gas into the bottom of the annular cavity 4 using the intermediate tube 5. The tracer gas exits from the bottom of the intermediate tube 5, allowing it to enter the micro-gap between the cement ring 3 and the sleeve 1. This displaces the existing gas in the micro-gap between the cement ring 3 and the sleeve 1 (within the annular cavity 4), maintaining the pressure within the annular cavity 4.

[0031] The tracer gas has a higher thermal conductivity than air, ensuring that the heat carried away by the tracer gas flowing through the leak point of sleeve 1 is greater than the heat carried away by the air flowing through the leak point. Therefore, when the tracer gas entering the micro-gap between the cement ring 3 and sleeve 1 enters sleeve 1 from the leak point, it absorbs / carries away heat from the periphery of the leak point, resulting in a temperature decrease in the periphery of the leak point. The tracer gas is helium or hydrogen. For example, if helium is used as the tracer gas, its thermal conductivity is 0.15 W / mK, which is 6 times that of air.

[0032] S3. Using the sleeve 1, tracer gas is drawn outwards while simultaneously collecting temperature change values ​​monitored by multiple temperature sensors. In step S3, the annular top valve 6 is opened, and gas is drawn outwards using the annular opening 7 of the sleeve, causing the pressure in the cavity between the sleeve 1 and the intermediate tube 5 to drop to a negative pressure. Therefore, when there is a leak in the sleeve 1, the tracer gas in the micro-gap between the cement ring 3 and the sleeve 1 can easily enter the cavity between the sleeve 1 and the intermediate tube 5 from the leak point and be drawn out of the sleeve 1. During this process, it can absorb / carry away the heat around the leak point in the sleeve 1, thereby causing a temperature decrease in the area around the leak point. The temperature change values ​​monitored by multiple temperature sensors are collected to identify the locations where the temperature drop in the sleeve 1 is significant.

[0033] In some embodiments, in step S3, the gas flow rate pumped outward through the annular opening 7 of the sleeve is greater than or equal to 0.1 L / min and less than or equal to 1 L / min. This is to pump gas at a constant low speed and maintain a slight negative pressure. For example, the gas flow rate pumped outward through the annular opening 7 of the sleeve is 0.3 L / min or 0.6 L / min.

[0034] S4. Determine the leakage status at multiple locations of the sleeve 1 based on the temperature change values ​​monitored by multiple temperature sensors. Specifically, in step S4, the leakage status at multiple locations of the sleeve 1 is determined based on at least one of the temperature decrease value and the temperature decrease rate monitored by multiple temperature sensors. Real-time monitoring of the temperature sensor array data indicates that if a local temperature drops sharply, tracer gas will flow through the leak point and carry away excess heat.

[0035] In some embodiments, in step S4, if the temperature decrease value monitored by the temperature sensor is greater than or equal to a first preset value, and / or the temperature decrease rate (temperature decrease gradient) monitored by the temperature sensor is greater than or equal to a second preset value, then the location of the sleeve 1 where the temperature sensor is located is determined to be a leak location. That is, whether there is a leak point at the location of the temperature sensor is determined based on at least one of the temperature decrease value and the temperature decrease rate (temperature decrease gradient) monitored by the temperature sensor.

[0036] In some embodiments, in step S4, after determining that the sleeve 1 has leaked based on the temperature change values ​​monitored by multiple temperature sensors, the evacuation from the annular opening 7 of the sleeve is stopped and the annular top valve 6 is closed. The pressure rise in the cavity between the sleeve 1 and the intermediate tube 5 is monitored to determine the leakage status of the sleeve 1. Specifically, in step S4, after stopping the evacuation from the annular opening 7 and closing the annular top valve 6, if the pressure rise rate in the cavity between the sleeve 1 and the intermediate tube 5 is less than 0.01 MPa / min, the leak point of the sleeve 1 is determined to be a micro-gap leak, meaning the leak point of the sleeve 1 has a small diameter and the leakage is not serious. If the pressure rise rate in the cavity between the sleeve 1 and the intermediate tube 5 is greater than or equal to 0.01 MPa / min, the leak point of the sleeve 1 is determined to be a large crack (sleeve 1 rupture), meaning the leak point of the sleeve 1 has a large diameter and the leakage is serious.

[0037] The micro-gap leakage detection method for the casing and cement sheath of a carbon dioxide geological storage well according to an embodiment of the present invention utilizes the thermal disturbance of tracer gas and the temperature sensor to monitor temperature changes. By monitoring the abnormal heat conduction caused by the flow of tracer gas, the micro-gap is located, completely avoiding gas composition analysis. This facilitates the detection of whether the casing 1 is leaking and makes it easy to determine the location of the leak point.

[0038] Therefore, the micro-gap leakage detection method between the casing and cement sheath of the carbon dioxide geological storage well according to the present invention facilitates the detection of whether the casing 1 is leaking and the location of the leakage point.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0043] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0044] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for detecting micro-gap leakage between the casing and cement sheath in a carbon dioxide geological storage well, wherein the carbon dioxide geological storage well includes a casing, a wellbore, and a cement sheath, the cement sheath being located within the annular cavity between the casing and the wellbore, characterized in that... Includes the following steps: S1. Multiple temperature sensors are installed at multiple locations on the inner wall of the sleeve, so that the multiple temperature sensors can monitor the temperature at multiple locations on the inner wall of the sleeve respectively. S2. Inject tracer gas into the bottom of the annular cavity to replace the original gas in the annular cavity, wherein the thermal conductivity of the tracer gas is greater than that of air so that the heat carried away by the tracer gas flowing through the sleeve leak point is greater than the heat carried away by the air flowing through the sleeve leak point. S3. Use the sleeve to draw tracer gas outward and simultaneously collect temperature change values ​​monitored by multiple temperature sensors; S4. Determine the leakage status at multiple locations of the bushing based on the temperature change values ​​monitored by the multiple temperature sensors.

2. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 1, characterized in that, In step S1, at least some of the plurality of temperature sensors are spaced apart in the vertical direction.

3. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 2, characterized in that, In step S1, the distance between two adjacent temperature sensors in the vertical direction is less than or equal to 20 meters, and at least some of the multiple temperature sensors are arranged at equal intervals in the vertical direction.

4. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 1, characterized in that, The carbon dioxide geological storage well includes an intermediate tube body located inside the casing. The top of the casing is provided with an annular top valve, which is used to close the annular opening of the casing between the upper opening of the casing and the intermediate tube body. In step S2, the annular top valve is closed, and tracer gas is injected into the bottom of the annular cavity using the intermediate tube. In step S3, the annular top valve is opened, and air is drawn outward through the annular opening of the sleeve, causing the pressure in the cavity between the sleeve and the intermediate tube to drop to a negative pressure.

5. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 4, characterized in that, In step S3, the gas flow rate for pumping air outward using the annular opening of the sleeve is greater than or equal to 0.1 L / min and less than or equal to 1 L / min.

6. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 4, characterized in that, In step S4, the leakage at multiple locations of the sleeve is determined based on at least one of the temperature decrease value and the temperature decrease rate monitored by the multiple temperature sensors.

7. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 6, characterized in that, In step S4, if the temperature drop value monitored by the temperature sensor is greater than or equal to a first preset value, and / or the temperature drop rate monitored by the temperature sensor is greater than or equal to a second preset value, then the location of the sleeve where the temperature sensor is located is determined to be a leak location.

8. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 6, characterized in that, In step S4, after determining that the sleeve has leaked based on the temperature change values ​​monitored by the multiple temperature sensors, the pumping of air out of the annular opening of the sleeve is stopped and the top valve of the annular space is closed. The pressure rise of the cavity between the sleeve and the intermediate tube is monitored in order to determine the leakage of the sleeve.

9. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 8, characterized in that, In step S4, after stopping the evacuation of air from the annular opening of the sleeve and closing the annular top valve, if the rate of pressure rise in the cavity between the sleeve and the intermediate tube is less than 0.01 MPa / min, the leak point of the sleeve is determined to be a micro-gap leak; if the rate of pressure rise in the cavity between the sleeve and the intermediate tube is greater than or equal to 0.01 MPa / min, the leak point of the sleeve is determined to be a large crack.

10. The method for detecting micro-gap leakage between the casing and cement sheath of a carbon dioxide geological storage well according to claim 1, characterized in that, The tracer gas is helium or hydrogen.

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