Drilling casing sealing detection system and sealing detection method

Abstract

The present invention discloses a sealing detection system and a sealing detection method for drilling casing, which relate to the field of drilling engineering. The sealing detection system includes a continuous pipe, a sealing component, a gas-liquid filling component and a pressure detection device. The system has high detection accuracy. In addition to being able to detect leakage at the connection between the casing segments, it can also detect leakage caused by defects in the casing itself. It can detect the casing sealing in all directions to avoid the problem of misjudgment or omission of the casing sealing. Compared with the existing current logging method, the casing sealing detection accuracy is greatly improved; the present invention forms a closed annular cavity between the continuous pipe and the casing to be tested with the help of upper and lower sealers, and can fill the closed annular cavity with water and air with the cooperation of the gas-liquid filling component, which can simulate the detection of the sealing performance of the casing in the well under high-pressure conditions, and is suitable for detecting all segmented connected casings in the well made of non-metallic and metal materials.

Description

Technical Field

[0001] The present invention relates to the field of drilling engineering, and in particular to a sealing detection system and a sealing detection method for a drilling casing. Background Art

[0002] In drilling projects, such as those for in-situ uranium leaching and similar hydrological drilling projects, the drill casing is connected in sections using couplings. For example, in in-situ uranium leaching, most mines use UPVC pipe as drill casing. Current logging is used to test the tightness of drilling casing. This involves connecting two probes to the test port of a standard ammeter. One probe is lowered to the bottom of the casing in the well and raised along the inner wall during testing. The other probe is buried in the surface soil, using the earth as the electrical conductor. The changes in the ammeter reading are observed and recorded. A constant ammeter reading indicates that the water in the casing is not connected to the formation, the casing is sealed properly, and there is no leakage. However, if the ammeter reading fluctuates and reaches a peak, it indicates that the water in the casing is connected to the formation (a leak exists), and the sealing performance is unsatisfactory.

[0003] While simple, this current logging method has its drawbacks: Because the wellhead is open, it operates under zero hydraulic pressure within the casing, and can generally detect the tightness of segmented joints. However, some casing defects can also develop cracks and fissures, such as microcracks in the casing or micropores at the threaded ends of couplings, leading to leaks. These leaks can cause injection solution loss and contaminate the formation. However, cracks and fissures in the casing typically do not open, making them virtually undetectable using the current method. This often results in false positives and missed detections using current logging. Summary of the Invention

[0004] The purpose of the present invention is to provide a drilling casing sealing detection system and sealing detection method to solve the problem that the above-mentioned existing current logging method cannot detect leakage caused by defects in the casing itself, which often leads to misjudgment or omission of casing sealing.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a drilling casing sealing detection system, comprising:

[0007] A coiled tubing, the coiled tubing being lowered into the casing to be tested and forming an annular space between the coiled tubing and the casing to be tested;

[0008] a sealing assembly, the sealing assembly comprising a first packer and a second packer, the first packer and the second packer both being annularly sleeved on the coiled tubing, one of the first packer and the second packer being used to seal an end of the annular space close to the bottom of the casing to be tested, and the other being used to seal an end of the annular space close to the wellhead, so as to form a closed annular cavity between the first packer and the second packer, a through hole being formed on a wall of the coiled tubing and communicating with the closed annular cavity;

[0009] a gas-liquid filling assembly, the gas-liquid filling assembly being used to fill liquid and gas into the coiled tubing;

[0010] A pressure detection device is used to detect the air pressure in the closed ring cavity.

[0011] Optionally, the first packer is sleeved on one axial end of the coiled tubing, the first packer is used to seal one end of the annular space close to the bottom of the casing to be tested, the first packer is located above the casing filter, and the axial spacing between the sealing position between the first packer and the inner wall of the casing to be tested and the casing filter is no more than 2m to 5m;

[0012] The second packer is sleeved on the other axial end of the coiled tubing, and is used to seal the end of the annular space close to the wellhead.

[0013] Optionally, the sealing position between the second packer and the inner wall of the casing to be tested is flush with the wellhead, or 0.5m to 1m lower than the wellhead.

[0014] Optionally, the first packer includes:

[0015] a joint connected to the coiled tubing;

[0016] An anchoring device, comprising a plurality of anchoring blocks movably provided on the side wall of the joint, the plurality of anchoring blocks being distributed along the circumference of the joint, the anchoring blocks being able to move outward to the inner wall of the casing to be tested under the action of liquid pressure and be pressed against the inner wall of the casing to be tested;

[0017] A sealing rubber sleeve, comprising at least one rubber ring, which is sleeved on the joint and can expand radially under the action of liquid pressure and squeeze against the inner wall of the casing to be tested to seal the space on both sides of the rubber ring;

[0018] A check valve is provided at the bottom of the joint and is used to prevent water above the first packer from flowing to below the first packer.

[0019] Optionally, the second packer includes:

[0020] a joint connected to the coiled tubing;

[0021] An anchoring device, comprising a plurality of anchoring blocks movably provided on the side wall of the joint, the plurality of anchoring blocks being distributed along the circumference of the joint, the anchoring blocks being able to move outward to the inner wall of the casing to be tested under the action of liquid pressure and be pressed against the inner wall of the casing to be tested;

[0022] The sealing rubber cylinder includes at least one rubber ring, which is sleeved on the joint. The rubber ring can expand radially under the action of liquid pressure and squeeze on the inner wall of the sleeve to be tested to seal the space on both sides of the rubber ring axially.

[0023] Optionally, the gas-liquid filling component includes:

[0024] A gas-liquid pressurization combination valve, comprising a first port, a second port, a third port, and a fourth port, each of which is interconnected, wherein the first port is connected to an end of the coiled tubing near the wellhead via a connecting pipe;

[0025] a first liquid filling unit, the first liquid filling unit being connected to the second port via a first liquid pipeline, the first liquid pipeline being provided with a second port valve;

[0026] a second liquid filling unit, the second liquid filling unit being connected to the third port via a second liquid pipeline, the second liquid pipeline being provided with a third port valve;

[0027] A gas filling unit is connected to the fourth port through a gas pipeline, a fourth port valve and the pressure detection device are provided on the gas pipeline, and the pressure detection device is located between the fourth port valve and the fourth port.

[0028] Optionally, the gas filling unit is a nitrogen filling unit for filling nitrogen into the coiled tubing; the first liquid filling unit and the second liquid filling unit are both clean water filling units for filling clean water into the coiled tubing.

[0029] Optionally, the pressure detection device is a gas pressure gauge.

[0030] The present invention also provides a drilling casing sealing detection method implemented by the above sealing detection system, comprising the steps of:

[0031] S1. lowering the coiled tubing into the casing to be tested, and placing the first packer and the second packer in corresponding isolation positions;

[0032] S2. Filling the coiled tubing with clean water using the gas-liquid filling assembly, actuating the first packer and the second packer to seal corresponding positions of the annular space, thereby forming the closed annular cavity between the first packer and the second packer;

[0033] S3, using the gas-liquid filling assembly to continue adding clean water into the coiled tubing until it is full;

[0034] S4, using the gas-liquid filling assembly to continue adding clean water to the coiled tubing filled with clean water, and stopping the water injection when the water pressure in the coiled tubing reaches 0.3 MPa to 0.8 MPa;

[0035] S5. Using the gas-liquid filling assembly to fill gas into the coiled tubing to increase the pressure inside the coiled tubing;

[0036] S6. When the gas pressure in the coiled tubing reaches 1.0 MPa to 1.5 MPa, the gas pressure in the coiled tubing is maintained constant. After the gas pressure is constant, the gas injection is stopped and timing is started. The gas pressure in the coiled tubing is detected by the pressure detection device at equal intervals.

[0037] S7. After the timing ends, the gas pressure value in the coiled tubing detected last time is determined, and the relationship between the decrease in the gas pressure in the coiled tubing compared to the value at the start of the timing and the preset amplitude value is determined. If the decrease is greater than the preset amplitude value, it is determined that the sealing of the casing to be tested is unqualified. If the decrease is less than the preset amplitude value, it is determined that the sealing of the casing to be tested is qualified.

[0038] Optionally, the following steps are also included:

[0039] S8. If the sealing performance of the casing to be tested is unqualified, the coiled tubing is lifted up as a whole in the casing to be tested, and steps S1 to S7 are repeated.

[0040] Compared with the prior art, the present invention has achieved the following technical effects:

[0041] The drilling casing sealing detection system proposed in the present invention has a novel and reasonable structure and high detection accuracy. In addition to being able to detect leakage at the connection points of the casing segments, it can also detect leakage caused by defects in the casing itself. It can fully detect the casing sealing and avoid the problem of misjudgment or omission of the casing sealing. Compared with the existing current logging method, the casing sealing detection accuracy is greatly improved. In addition, the drilling casing sealing detection system is easy to operate and reliable in operation.

[0042] Furthermore, compared to existing current logging methods, which require an open wellhead, the drilling casing sealing detection system proposed in this invention utilizes upper and lower packers to form a closed annular cavity between the coiled tubing and the casing to be tested. This cavity can be filled with water and air with the cooperation of a gas-liquid injection assembly, simulating the high-pressure conditions used to test the sealing performance of the casing in the well. These high-pressure conditions are identical to those found in well operations, reflecting the sealing performance of the casing in the well under high-pressure operating conditions and ensuring reliable testing. Furthermore, existing detection methods cannot be implemented in the dry sections of the casing. However, the present invention, through the provision of upper and lower packers, can form a closed annular cavity in each section of the casing, enabling effective and comprehensive sealing testing of the casing.

[0043] Furthermore, compared to existing current logging methods, which require casing as an electrical insulating medium and are only suitable for testing the sealing properties of non-metallic casing made of materials such as UPVC and PE, the present invention is not limited to casing materials and is suitable for testing the sealing properties of all non-metallic and metallic segmented casings in wells. Furthermore, this drilling casing sealing testing system offers the advantages of high efficiency, low labor intensity, and high testing quality.

[0044] The drilling casing sealing detection method proposed in the present invention is implemented by adopting the above-mentioned drilling casing sealing detection system, and has the characteristics of simple operation, high work efficiency, low labor intensity and high detection quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 This is a schematic structural diagram of a drilling casing sealing detection system disclosed in an embodiment of the present invention;

[0047] Figure 2 This is a test principle diagram of a drilling casing sealing detection system disclosed in an embodiment of the present invention;

[0048] Wherein, the accompanying drawings are marked as follows:

[0049] 100. Drilling casing sealing detection system;

[0050] 1. Casing filter, 2. Casing to be tested, 3. Coiled tubing, 4. First packer, 5. Lower anchor block, 6. Lower sealing rubber sleeve, 7. Check valve, 8. Second packer, 9. Upper sealing rubber sleeve, 10. Upper anchor block, 11. Connecting pipe, 12. Gas-liquid pressurization combination valve, 13. Second port valve, 14. Third port valve, 15. Fourth port valve, 16. Gas pressure gauge, 17. Through hole, 18. Closed annular cavity, 19. Wellhead, 20. First port, 21. Second port, 22. Third port, 23. Fourth port, 24. First liquid filling unit, 25. Second liquid filling unit, 26. Gas filling unit. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] One of the purposes of the present invention is to provide a drilling casing sealing detection system to solve the problem that the existing current logging method cannot detect leakage caused by defects in the casing itself, which often leads to misjudgment or omission of casing sealing.

[0053] Another object of the present invention is to provide a drilling casing sealing detection method implemented by the above-mentioned sealing detection system to solve the problem that the existing current logging method cannot detect leakage caused by defects in the casing itself, which often leads to misjudgment or omission of the casing sealing.

[0054] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] Example 1

[0056] like Figure 1As shown, this embodiment provides a drilling casing seal detection system 100 for detecting the sealability of a casing in a well, i.e., a casing to be tested 2. The seal detection system primarily comprises a first packer 4 located below, a second packer located at the wellhead, a coiled tubing 3, a connecting pipe 11, a gas-liquid pressurization combination valve 12, a first liquid filling unit 24, a second liquid filling unit 25, a gas filling unit 26, and a gas pressure gauge 16. The first packer 4 is placed at the bottom of the casing 2 to be tested, and its structure includes a joint or a plug joint that can be connected to the inner pipe (i.e., the continuous pipe 3), a lower anchoring device, a lower sealing rubber tube 6 and a check valve 7. The joint or the plug joint is connected to the inner pipe (i.e., the continuous pipe 3), and the lower anchoring device includes a plurality of lower anchoring blocks 5. The lower anchoring blocks 5 are wedge-shaped and movably plugged into the side wall of the joint or the plug joint. The side wall of the joint or the plug joint is provided with a plurality of lower anchoring blocks 5 along its circumference. Under the action of liquid pressure, the plurality of lower anchoring blocks 5 can be synchronously moved outward to the inner wall of the casing 2 to be tested and squeezed into the inner wall of the casing 2 to be tested. The first packer 4 is mounted on the wall of the casing 2 to be tested, preventing it from moving up and down relative to the casing 2 to be tested. The lower sealing rubber tube 6 is composed of two rubber rings, which are fitted over the outer wall of the joint or plug connector and spaced axially from the lower anchoring device. Under the action of liquid pressure, the two rubber rings can expand radially and squeeze against the inner wall of the casing 2 to be tested, thereby isolating the hydraulic connection between the upper part of the lower sealing rubber tube 6 and the lower part of the lower sealing rubber tube 6. A check valve 7 is installed at the bottom of the first packer 4. This check valve 7 only allows water to flow from bottom to top, not from top to bottom. The first packer 4 serves as the upper packer, and its lower sealing rubber tube 6 is located below the lower anchoring device. The outer dimensions of the first packer 4 are smaller than the inner diameter of the casing 2 to be tested, and the size ratio between the first packer 4 and the inner diameter of the casing 2 to be tested is preferably 1:0.6-0.9. After being lowered, the distance between the lower rubber ring in the lower sealing rubber tube 6 and the casing filter 1 is preferably no more than 2-5 meters. That is, it should be ensured that after the casing 2 to be tested is lowered, the lower sealing rubber tube 6 is located above the casing filter 1, and the distance between the two is no more than 2-5 meters. Among them, the lower anchoring device, as the main anchoring component of the first packer 4, can include 2-4 lower anchor blocks 5, and further preferably includes 4 lower anchor blocks 5, and the 4 lower anchor blocks 5 are evenly distributed around the periphery of the joint or plug joint of the first packer 4.

[0057] In this embodiment, the second packer 8 serves as an upper packer and is positioned near the wellhead 19. The structure of the second packer 8 is substantially the same as that of the first packer 4, with the only difference being that the second packer 8 is not equipped with a check valve. After the casing 2 to be tested is lowered, the upper anchor block 10 of the second packer 8 is preferably positioned flush with the wellhead 19, or 0.5 to 1.0 meters below the wellhead 19. In this embodiment, the outer dimensions of the second packer 8 are the same as those of the first packer 4. The outer dimensions of the second packer 8 are smaller than the inner diameter of the casing 2 to be tested, and the size ratio of the second packer 8 to the inner diameter of the casing 2 to be tested is preferably 1:0.6 to 0.9. The upper anchoring device, serving as the main anchoring component of the second packer 8, may include 2 to 4 upper anchor blocks 10, and more preferably includes 4 upper anchor blocks 10, with the 4 upper anchor blocks 10 evenly distributed around the periphery of the joint or plug joint of the second packer 8.

[0058] In this embodiment, the coiled tubing 3 is preferably an integrally formed continuous tubing body to eliminate inaccurate testing results due to inherent factors. The coiled tubing 3 can be made of PE, PVC, PA, PPS, PEEK, etc. It is a cylindrical tube with an outer diameter preferably between 40 mm and 80 mm and a wall thickness preferably between 4 mm and 10 mm. The lower portion of the coiled tubing 3 is connected to the first packer 4, and the upper portion is connected to the second packer 8. After the coiled tubing 3 is lowered into the casing 2 to be tested, an annular space is formed between the outer wall of the coiled tubing 3 and the inner wall of the casing 2 to be tested. Once the coiled tubing 3 is lowered into place and the first and second packers 4, 8 form a squeeze seal with the inner wall of the casing 2 to be tested, a closed annular cavity 18, sealed at both ends, is formed between the lower sealing rubber sleeve 6 of the first packer 4 and the upper sealing rubber sleeve 9 of the second packer 8. The coiled tubing 3 has a plurality of through holes 17 formed on its sidewall between the first packer 4 and the second packer 8, so that the water in the coiled tubing 3 is connected to the closed annular cavity 18. The diameter of the through holes 17 is preferably 2 mm to 10 mm.

[0059] In this embodiment, the coiled tubing 3 is connected to the first port 20 of the gas-liquid pressurization combination valve 12 via a connecting tube 11. The connecting tube 11 is preferably a continuous tubing with connectors at both ends. The material of the connecting tube 11 can be PE, PVC, PA, PPS, PEEK, etc., or steel or iron pipes can also be used. The connector on the connecting tube 11 can be made of steel or iron and serves to connect the second packer 8 to the gas-liquid pressurization combination valve 12. The connector can be a flange connection, a threaded connection, a socket connection, or a threaded ferrule connection, with the threaded ferrule connection being the most common.

[0060] In this embodiment, the gas-liquid pressurization combination valve 12 is essentially a multi-way valve, more specifically, preferably a non-standard four-way valve, having four interconnected ports: a first port 20, a second port 21, a third port 22, and a fourth port 23. The first port 20 is connected to a connector at one end of the connecting pipe 11 and is not provided with a valve. The second port 21 is connected to a first liquid filling unit 24 via a first liquid pipeline, on which a second port valve 13 is provided. The third port 22 is connected to a first liquid filling unit 25 via a second liquid pipeline, on which a third port valve 14 is provided. The fourth port 23 is connected to a gas filling unit 26 via a gas pipeline, on which a fourth port valve 15 and a gas pressure gauge 16 are provided. The gas pressure gauge 16 is located between the fourth port 23 and the fourth port valve 15 to ensure that the gas pressure gauge 16 remains connected to the gas-liquid pressurization combination valve 12. By controlling the opening and closing of the second port valve 13, the third port valve 14, and the fourth port valve 15, different filling units can be controlled to communicate with the first port 20. The gas filling unit 26 is preferably a nitrogen filling unit, which can be composed of a connecting pipe and a nitrogen bottle, or a connecting pipe, a gas pump, and a nitrogen tank. When the fourth port valve 15 is opened, nitrogen gas at a certain pressure can be added to the coiled tubing 3 through the nitrogen filling unit. The first liquid filling unit 24 and the second liquid filling unit 25 are preferably both fresh water filling units, which can be composed of a connecting pipe, a water pump, and a water tank. The first liquid filling unit 24 and the second liquid filling unit 25 can each be equipped with an independent water tank, or they can share the same water tank. When the first liquid filling unit 24 and the second liquid filling unit 2 share the same water tank, the water pump outlet connected to the water tank can be connected to a common three-way valve, with one outlet of the three-way valve connected to the first liquid pipeline and the other outlet connected to the second liquid pipeline. The difference between the first liquid filling unit 24 and the second liquid filling unit 25 is that the first liquid filling unit 24 is used to inject clean water at a large flow rate and a certain pressure into the coiled tubing 3 under the control of the second port valve 13, while the second liquid filling unit 25 is used to inject clean water at a small flow rate and a certain pressure into the coiled tubing 3 under the control of the third port valve 14. As the name suggests, during operation, the water injection flow rate of the second liquid filling unit 25 is smaller than the water injection flow rate of the first liquid filling unit 24.

[0061] The process and principle of drilling casing sealing detection using the above-mentioned drilling casing sealing detection system 100 are as follows:

[0062] Step S1, measuring and marking the length of the coiled tubing 3, and lowering the coiled tubing 3 so that the first packer 4 and the second packer 8 are respectively located at predetermined positions on the casing 2 to be tested;

[0063] Step S2: adding clean water to the coiled tubing 3 to force the anchor blocks and sealing rubber sleeves of the first and second packers 4 and 8 to operate, thereby forming a closed annular cavity 18 between the coiled tubing 3, the casing 2 to be tested, the first and second packers 4 and 8;

[0064] Step S3: Close the third port valve 14 and the fourth port valve 15, open the second port valve 13, and inject a large amount of clean water into the coiled tubing 3 at a high flow rate through the first liquid injection unit 24 until the coiled tubing 3 is full, and then close the second port valve 13;

[0065] Step S4: Open the third port valve 14 while the fourth port valve 15 is closed. High-pressure clean water is injected into the coiled tubing 3 at a low flow rate through the second liquid injection unit 25. When the water pressure in the coiled tubing 3 reaches 0.3 MPa to 0.8 MPa, close the third port valve 14.

[0066] Step S5: Open the fourth port valve 15 and use the gas filling unit 26 to pressurize the coiled tubing 3. When the gas pressure in the coiled tubing 3 reaches 1.0 MPa to 1.5 MPa, the gas pressure is maintained constant. For example, when the gas pressure in the coiled tubing 3 reaches 1.2 MPa, the gas pressure is maintained constant.

[0067] Step S6: After the gas pressure in the coiled tubing 3 becomes constant, the fourth port valve 15 is closed to cut off the gas supply to the gas filling unit 26. Simultaneously, a timer is started, and the data from the gas pressure gauge 16 is read every 1.0 to 3.0 minutes (a constant time interval is selected, such as 1 minute, 2 minutes, or 3 minutes), for a total of 4 to 8 readings.

[0068] Step S7, after the timing is completed, the gas pressure value last read by the gas pressure gauge 16 is determined, and the relationship between the decrease in the gas pressure value first read at the start of the timing and the preset value is determined. A gas pressure decrease of 2% to 5% (one of the constant values) is used as a standard. If the gas pressure decreases within the range of 2% to 5% (one of the constant values), the sealing of the casing 2 to be tested in the well is considered to be excellent or qualified (for example, a decrease of less than 2% is excellent, and a decrease of between 2% and 5% is qualified). Conversely, if the gas pressure decreases within the range of 2% to 5%, the sealing of the casing 2 to be tested in the well is considered to be unqualified.

[0069] After determining that the sealing is unqualified, step S8 is often required. That is, when the sealing in the well is considered unqualified, it is necessary to open the second port valve 13 to relieve pressure, unseal the packer, and lift the entire sealing detection system. After the first packer 4 is lifted to a certain height, the above steps S1 to S7 are repeated and re-tested until the specific leakage location of the casing 2 to be tested is found, which lays the foundation for casing repair.

[0070] In actual operation, in step S7, the gas pressure gauge 16 is typically read every two minutes, for a total of 10 minutes of stabilization, resulting in five readings. When the timing ends, if the gas pressure decreases by less than 2%, the casing seal is considered excellent. If the gas pressure decreases by less than 5%, the casing seal is considered acceptable. If the gas pressure decreases by more than 5%, the casing seal is considered unacceptable.

[0071] It can be seen that the sealing detection system and sealing detection method of the above-mentioned drilling casing proposed in this technical solution can detect the sealing performance of the casing in the well under high-pressure conditions of 1.1MPa to 1.5MPa. The high-pressure conditions are the same as the conditions of well operations, but they simulate the extreme conditions in the well, which can reflect the sealing performance of the casing in the well under high-pressure operating conditions. The sealing detection system has high working efficiency, low labor intensity, and high detection quality, and is suitable for all segmented well casings made of non-metallic and metal materials.

[0072] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all perspectives, the embodiments should be regarded as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description. It is intended that all changes that fall within the meaning and range of equivalents of the claims be included in the present invention, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

[0073] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A drilling casing sealing detection system, characterized in that: include: A coiled tubing, the coiled tubing being lowered into the casing to be tested and forming an annular space between the coiled tubing and the casing to be tested; a sealing assembly, the sealing assembly comprising a first packer and a second packer, the first packer and the second packer both being annularly sleeved on the continuous tubing, one of the first packer and the second packer being used to seal an end of the annular space close to the bottom of the casing to be tested, and the other being used to seal an end of the annular space close to the wellhead, so as to form a closed annular cavity between the first packer and the second packer, a through hole communicating with the closed annular cavity being provided on the wall of the continuous tubing; the second packer comprising a joint connected to the continuous tubing, an anchoring device and a sealing rubber sleeve, the anchoring device comprising a plurality of anchor blocks movably provided on the side wall of the joint, the plurality of anchor blocks being distributed along the circumference of the joint, the anchor blocks being able to move outward to the inner wall of the casing to be tested under the action of liquid pressure and be squeezed against the inner wall of the casing to be tested; The sealing rubber sleeve includes at least one rubber ring, which is sleeved on the joint and can expand radially under the action of liquid pressure and squeeze against the inner wall of the casing to be tested to seal the space on both sides of the rubber ring axially; the first packer has a structure identical to that of the second packer, and the first packer also includes a check valve, which is provided at the bottom of the joint of the first packer and is used to prevent water above the first packer from flowing to the bottom of the first packer; a gas-liquid filling assembly, the gas-liquid filling assembly being used to fill liquid and gas into the coiled tubing; A pressure detection device is used to detect the air pressure in the closed ring cavity.

2. The drilling casing sealing detection system according to claim 1, characterized in that: The first packer is sleeved on one axial end of the coiled tubing and is used to seal the end of the annular space close to the bottom of the casing to be tested. The first packer is located above the casing filter, and the sealing position between the first packer and the inner wall of the casing to be tested and the axial spacing of the casing filter is 2m to 5m; the second packer is sleeved on the other axial end of the coiled tubing and is used to seal the end of the annular space close to the wellhead.

3. The drilling casing sealing detection system according to claim 2, characterized in that: The sealing position between the second packer and the inner wall of the casing to be tested is flush with the wellhead, or 0.5m to 1m lower than the wellhead.

4. The drilling casing sealing detection system according to any one of claims 1 to 3, characterized in that: The gas-liquid filling assembly comprises: A gas-liquid pressurization combination valve, comprising a first port, a second port, a third port, and a fourth port, each of which is interconnected, wherein the first port is connected to an end of the coiled tubing near the wellhead via a connecting pipe; a first liquid filling unit, the first liquid filling unit being connected to the second port via a first liquid pipeline, the first liquid pipeline being provided with a second port valve; a second liquid filling unit, the second liquid filling unit being connected to the third port via a second liquid pipeline, the second liquid pipeline being provided with a third port valve; A gas filling unit is connected to the fourth port through a gas pipeline, a fourth port valve and the pressure detection device are provided on the gas pipeline, and the pressure detection device is located between the fourth port valve and the fourth port.

5. The drilling casing sealing detection system according to claim 4, characterized in that: The gas filling unit is a nitrogen filling unit for filling nitrogen into the coiled tubing; the first liquid filling unit and the second liquid filling unit are both clean water filling units for filling clean water into the coiled tubing.

6. The drilling casing sealing detection system according to claim 4, characterized in that: The pressure detection device is a gas pressure gauge.

7. A method for detecting the sealing of a drilling casing using the sealing detection system according to any one of claims 1 to 6, characterized in that: Including steps: S1. lowering the coiled tubing into the casing to be tested, and placing the first packer and the second packer in corresponding isolation positions; S2. Filling the coiled tubing with clean water using the gas-liquid filling assembly, actuating the first packer and the second packer to seal corresponding positions of the annular space, thereby forming the closed annular cavity between the first packer and the second packer; S3, using the gas-liquid filling assembly to continue adding clean water into the coiled tubing until it is full; S4. Continue to add clean water to the coiled tubing filled with clean water using the gas-liquid filling assembly. Stop the water injection when the water pressure in the coiled tubing reaches 0.3 MPa to 0.8 MPa. S5. Using the gas-liquid filling assembly to fill gas into the coiled tubing to increase the pressure inside the coiled tubing; S6. When the gas pressure in the coiled tubing reaches 1.0 MPa to 1.5 MPa, the gas pressure in the coiled tubing is maintained constant. After the gas pressure is constant, the gas injection is stopped and timing is started. The gas pressure in the coiled tubing is detected by the pressure detection device at equal intervals. S7. After the timing ends, the gas pressure value in the coiled tubing detected last time is determined, and the relationship between the decrease in the gas pressure in the coiled tubing compared to the value at the start of the timing and the preset amplitude value is determined. If the decrease is greater than the preset amplitude value, it is determined that the sealing of the casing to be tested is unqualified. If the decrease is less than the preset amplitude value, it is determined that the sealing of the casing to be tested is qualified.

8. The method for detecting the sealing of a drilling casing according to claim 7, wherein: The method further includes the step: S8, if the sealing performance of the casing to be tested is unqualified, lifting the coiled tubing as a whole in the casing to be tested, and repeating steps S1 to S7.

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