A drill string conveyance type casing damage detection process string and method

Abstract

This invention provides a drill string and method for casing damage detection using a drill string delivery system, relating to the field of offshore oilfield workover technology. The string includes, from top to bottom, drill pipe, a magnetic flux leakage (MF) detection tool, and a centralizer. The drill pipe delivers the MF detection tool to a designated detection position within the casing. The MF detection tool includes a detection module, a data storage module connected to the detection module, and a motion sensing device for detecting damage to the inner and outer walls of the casing, storing detection data, and sensing the string's raising and lowering movements. The centralizer constrains the central axis of the MF detection tool to be near the central axis of the string. This drill string delivery system for casing damage detection, using the aforementioned drill string delivery system, replaces traditional cable delivery with drill pipe, eliminating the need for additional cables, steel wires, or other equipment during the detection process, thus improving operational convenience and meeting the requirements for precise casing damage detection.

Description

Technical Field

[0001] This invention relates to the field of offshore oilfield well workover technology, and in particular to a drill string delivery system for casing damage detection and its method. Background Technology

[0002] With the increasing number of wells with casing damage in old oilfields in China, and the trend of regional development, the demand for casing damage detection in old oilfields is growing. At the same time, the requirements for detection are becoming more refined. It is no longer limited to qualitative judgments such as whether there is casing damage, holes, or single local damage, but requires quantitative data support, such as the specific size of holes and defects, and the percentage change in wall thickness. This provides technical support for efficient wellbore integrity management and intelligent wellbore intervention.

[0003] like Figure 1 As shown, most current methods for detecting cable damage rely on cable testing. The testing process requires additional mobilization of personnel for steel wire, cables, and related equipment, resulting in a large-scale operation and poor testing convenience, which is not conducive to large-scale regional operations.

[0004] Therefore, there is an urgent need for a drill string delivery system and method for casing damage detection to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a drill string-driven casing damage detection process string and method to solve the technical problems of existing technologies that require large-scale equipment and personnel for cable-driven casing damage detection, making operation inconvenient and unsuitable for large-scale regional operations, thereby improving oilfield recovery. The various technical effects of the preferred technical solutions provided by this invention are detailed below.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a drill string for casing damage detection, comprising, from top to bottom, drill pipe, a magnetic flux leakage detection tool, and a centralizer, wherein: The drill pipe is used to deliver the magnetic flux leakage detection tool to the designated detection position inside the casing; The magnetic flux leakage detection tool includes a detection module, a data storage module connected to the detection module, and a motion sensing device, used to detect damage to the inner and outer walls of the casing, store detection data, and sense the lifting and lowering of the tubing. The centralizer is used to constrain the central axis of the magnetic flux leakage detection tool to be near the central axis of the tubing.

[0007] Preferably, it further includes a guide, which is coaxially connected to the end of the stabilizer away from the magnetic flux leakage detection tool. The bottom of the guide is inclined to guide the bottom of the tubing to avoid the step inside the casing during the process of the tubing being lowered into the casing.

[0008] Preferably, the guide is a hollow structure used to provide a fluid outlet at the bottom of the tubing string, thereby creating a circulation channel between the tubing string and the casing annulus.

[0009] Preferably, it also includes a safety connector, which is disposed between the magnetic flux leakage detection tool and the centralizer. When the tubing gets stuck, the pull force of lifting the tubing reaches a preset threshold, and the tubing section below the safety connector is automatically released to achieve unblocking.

[0010] The present invention provides a drill string delivery-type casing damage detection method, which uses the above-mentioned drill string delivery-type casing damage detection process string and includes the following steps: S1: Pre-flush: Lower the flushing string, which is connected to the scraper and guide, into the casing section above the top packer, perform reverse circulation flushing until the returned fluid is clean, and then pull out the flushing string; S2: Running the tubing: After checking the well condition data and confirming that the maximum dogleg deviation does not exceed the maximum passability value of the magnetic flux leakage detection tool, run the tubing. S3: Data Acquisition: Set the working mode of the leakage magnetic field detection tool according to the casing damage condition, collect casing damage data through the detection module and store it in the data storage module; S4: Data playback: Remove the tubing, read the stored detection data, and analyze and judge the damage to the tubing.

[0011] Preferably, in step S3, the working mode includes a qualitative detection mode, in which the magnetic flux leakage detection tool is activated when the tube is lowered, and data is collected once during the lowering and lifting of the tube.

[0012] Preferably, in step S3, the working mode includes a quantitative detection mode, in which the magnetic flux leakage detection tool is set to delayed start, and data acquisition is triggered after the tubing is lowered into place, and data is collected only during the process of lifting the tubing.

[0013] Preferably, the magnetic flux leakage detection tool is equipped with a sleep mechanism and a wake-up mechanism: When the tubing is paused during insertion and the preset conditions are met, the magnetic flux leakage detection tool triggers a sleep mode. When the tubing resumes its lifting and lowering motion, the motion sensing device senses the motion and triggers a wake-up, and the magnetic flux leakage detection tool resumes data acquisition.

[0014] Preferably, the instantaneous speed of the tubing in step S2 (lowering the tubing) and in step S4 (removing the tubing) does not exceed 15 m / min.

[0015] Preferably, in step S1, the packer is scraped up and down at least three times at the packer setting position, followed by a discharge rate > 50m³. 3 Reverse circulation well washing is performed under conditions of / h and pressure <5MPa until the returned fluid is clean.

[0016] This invention provides a drill string and method for casing damage detection using a drill string delivery system. The system comprises a drill pipe, a magnetic flux leakage (MF) detection tool, and a centralizer connected sequentially from top to bottom. The drill pipe replaces the traditional cable delivery, eliminating the need for additional cable wires and supporting equipment. It is suitable for wells with inclination greater than 60° and horizontal wells, eliminating the influence of well inclination on the MF detection process and solving the problem of traditional MF detection methods being unable to reach complex well sections. The MF detection tool features detection, storage, and motion sensing functions, resulting in a more compact and highly integrated structure. The elastic centralizer constrains the central axis of the MF detection tool to near the central axis of the drill string, ensuring a uniform distance between the detection module and the casing inner wall, significantly improving the accuracy of MF detection and meeting the requirements for refined detection. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the background technology of this invention; Figure 2 This is a schematic diagram of a structural embodiment of the drill string conveying casing damage detection process string of the present invention; Figure 3 This is a schematic diagram illustrating the working principle of the magnetic flux leakage detection tool in the drill string of the present invention, which is a process for detecting casing damage using a drill string.

[0019] In the diagram: 10. Cable; 1. Drill pipe; 2. Magnetic flux leakage detection tool; 21. Detection module; 22. Data storage module; 23. Motion sensing device; 3. Centralizer; 4. Guide; 5. Safety joint; A. Top packer; B. Isolation packer I; C. Isolation packer II; D. Artificial bottom hole. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] In the description of this invention, it should be understood that the terms "center," "side," "length," "width," "height," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. 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. Therefore, they should not be construed as limitations on this invention.

[0022] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] Figure 2 This is a structural schematic diagram of this embodiment, as shown below. Figure 2 As shown, this embodiment provides a drill string for casing damage detection, which includes a drill pipe 1, a magnetic flux leakage detection tool 2, and a centralizer 3 connected sequentially from top to bottom.

[0024] The drill pipe 1 is used to transport the magnetic flux leakage detection tool 2 to the designated detection position inside the casing. In this embodiment, the drill pipe 1 is a standard oilfield drill pipe with an outer diameter that can adapt to the inner diameter of the casing, and has the structural strength to withstand downhole pressure, torque, and circulating fluid pressure.

[0025] Figure 3 This is a schematic diagram illustrating the working principle of the magnetic flux leakage detection tool in this embodiment, as follows: Figure 3As shown, the magnetic flux leakage detection tool 2 includes a detection module 21, a data storage module 22 connected to the detection module 21, and a motion sensing device 23, used to detect damage to the inner and outer walls of the casing, store detection data, and sense the lifting and lowering movements of the casing. Specifically, in this embodiment, the detection module 21 uses magnetic sensors arranged in a ring array to accurately detect damage such as breaks, holes, and thinning of the inner and outer walls of the casing. The data storage module 22 has a built-in high-speed storage chip and communicates bidirectionally with the detection module via a data bus to store detection data in real time, with a data retention time of not less than 96 hours. The motion sensing device 23 includes a MEMS accelerometer sensor to sense the lifting, lowering, or stationary movement of the casing in real time.

[0026] The centralizer 3 is used to constrain the central axis of the magnetic flux leakage detection tool 2 to be near the central axis of the tubing. In this embodiment, the centralizer 3 includes multiple evenly distributed elastic support arms. During operation, the support arms elastically open and fit against the inner wall of the tubing, aligning the magnetic flux leakage detection tool 2 at the center position of the tubing, thereby improving the centering of the magnetic flux leakage detection tool 2 in the tubing and improving the detection accuracy of the magnetic flux leakage detection tool 2.

[0027] This drill string-based casing damage detection process string consists of drill pipe 1, a magnetic flux leakage (MF) detection tool 2, and a centralizer 3 connected sequentially from top to bottom. It replaces traditional cable delivery with drill pipe, eliminating the need for additional cable wires and related equipment. Suitable for wells with inclination greater than 60° and horizontal wells, it eliminates the influence of well inclination on the cable-driven MF detection process, solving the problem of traditional cable-driven detection being unable to reach complex well sections. The MF detection tool 2 features detection, storage, and motion sensing functions, resulting in a more compact and highly integrated structure. The elastic centralizer constrains the central axis of the MF detection tool 2 to near the central axis of the drill string, ensuring a uniform distance between the detection module and the casing inner wall, significantly improving the accuracy of MF detection and meeting the needs of refined detection.

[0028] As an optional implementation, a guide 4 is also included. The guide 4 is coaxially connected to the end of the stabilizer 3 away from the magnetic flux leakage detection tool 2. The bottom of the guide 4 is inclined to guide the bottom of the tubing to avoid the step inside the casing during the process of lowering the tubing into the casing, so as to smoothly lower the tubing into the casing.

[0029] In this embodiment, the guide 4 has a 15°-60° tilt angle at its bottom. This tilted surface guides the bottom of the tubing to avoid steps, scale protrusions, or deformed sections within the casing during tubing insertion. This effectively solves the problem of tubing getting stuck on steps within the casing during insertion, improving the smoothness of tubing insertion.

[0030] By coaxially connecting the guide 4 and the centralizer 3, the overall centering of the tubing is not changed, ensuring that the detection accuracy is not affected by the guide structure.

[0031] As an optional implementation, the guide 4 is a hollow structure used to provide a fluid outlet at the bottom of the tubing string, creating a circulation channel between the tubing string and the casing annulus.

[0032] Specifically, the drill string for casing damage detection has a hollow internal structure, and the guide 4 is an axially penetrating hollow structure. The hollow guide 4 provides a fluid outlet at the bottom of the string, creating a bidirectional circulation channel between the inner string and the casing annulus. This allows for auxiliary operations such as forward and reverse circulation well washing and acidizing without the need to trip the string to change tools, thus improving operational efficiency.

[0033] Preferably, the guide 4 is a hollow structure with a smooth inner wall to avoid fluid turbulence and pressure loss, and to ensure pressure stability during cyclic operation.

[0034] As an optional implementation, a safety connector 5 is also included. The safety connector 5 is disposed between the magnetic flux leakage detection tool 2 and the centralizer 3. When the tubing is stuck, the tubing section below the safety connector 5 is automatically released when the pulling force of the tubing reaches a preset threshold to achieve unblocking.

[0035] In this embodiment, the safety connector 5 is coaxially connected between the magnetic flux leakage detection tool 2 and the centralizer 3. It can employ a shear pin release structure. When the tubing string becomes stuck, if the pulling force reaches a preset threshold, such as 50 kN, the shear pin breaks, automatically releasing the tubing string section below the safety connector 5, including the centralizer 3 and guide 4, thus achieving safe unsticking and retrieval of the tubing string. This avoids the entire tubing string remaining downhole, reducing the risk and economic loss of well workover operations. Furthermore, since no additional special tools are required for release, the operation is more convenient and does not damage the magnetic flux leakage detection tool 2, ensuring the security of the detection data.

[0036] This embodiment also provides a drill string delivery-type casing damage detection method, which uses the above-mentioned drill string delivery-type casing damage detection process string and includes the following steps: S1: Pre-flush: Lower the flushing string, which is connected to the scraper and guide, into the casing section above the top packer, perform reverse circulation flushing until the returned fluid is clean, and then pull out the flushing string; In actual testing, a spring-loaded scraper can be used, with the scraper diameter adapted to the inner diameter of the casing. The flushing string, connected to the scraper and guide, is lowered into the casing section above the top packer. During the lowering process, the lowering speed is controlled to prevent jamming, drill bit jackknock, or other issues.

[0037] Specifically, the top packer setting position is scraped three times, both upper and lower, and after scraping, the well is flushed with reverse circulation until the water is completely returned. The flushing flow rate should be greater than 50 m³ / h. 3 / h, well washing pressure less than 5MPa, pull out scraper string.

[0038] S2: Running the tubing: After checking the well condition data and confirming that the maximum dogleg deviation does not exceed the maximum passability value of the magnetic flux leakage detection tool, run the tubing. In this embodiment, before running the tubing, the well inclination data needs to be checked to confirm that the maximum dogleg angle does not exceed the maximum dogleg angle passability value of the tool. After confirming the tubing's runability, the drill string delivery type casing damage detection process tubing is run. The tubing is connected in the following order from top to bottom: drill pipe 1, magnetic flux leakage detection tool 2, safety joint 5, centralizer 3, and guide 4.

[0039] S3: Data Acquisition: Set the working mode of the leakage magnetic field detection tool according to the casing damage condition, collect casing damage data through the detection module and store it in the data storage module; The operating modes include qualitative and quantitative detection modes. In qualitative detection mode, the magnetic flux leakage (MF) detection tool is activated when the tubing is lowered, and data is collected once during the lowering and once during the lifting of the tubing. In quantitative detection mode, the MF detection tool is set to start with a delay, and data collection is triggered after the tubing is lowered into place, collecting data only during the lifting of the tubing.

[0040] It is important to control the lowering speed during the lowering process to prevent jamming, jackknotting, or other problems.

[0041] The magnetic flux leakage detection tool in this embodiment is equipped with a sleep mechanism and a wake-up mechanism: When the tubing is suspended due to special reasons and the preset conditions are met, the magnetic flux leakage detection tool 2 will trigger a sleep mode to save power and extend the tool's working time. When the casing resumes its lifting and lowering operation, the motion sensing device 23 in the magnetic flux leakage detection tool 2 senses the casing movement and triggers the activation of the tool. The tool then resumes operation and continues to collect casing damage data according to the casing's movement. The data is stored within the tool, and is replayed after the tool is lifted out with the casing to determine the extent of casing damage.

[0042] In actual operation, under good well conditions and with ample operating time, the magnetic flux leakage detection tool 2 collects detection data during both the lowering and raising processes. At this time, the magnetic flux leakage detection tool 2 is set to be in a fully powered-on state. When the tubing string carrying the magnetic flux leakage detection tool 2 is lowered into the well, casing data can be collected. Data is collected twice during the lowering and raising processes. The detection data during the lowering and raising processes can be compared to verify the validity and accuracy of the data. Meanwhile, the instantaneous speed during tripping should not exceed 15m / min.

[0043] In cases of poor well conditions or tight operating time, set the magnetic flux leakage detection tool 2 to a dormant state, quickly lower the tubing string, and activate the magnetic flux leakage detection tool 2 after the tubing string is in place. Then, pull up the tubing string and collect casing damage data during the pulling process. To ensure the validity and accuracy of the data, the instantaneous speed during the tripping process should not exceed 15 m / min.

[0044] S4: Data playback: Remove the tubing string, read the stored detection data, and analyze and determine the casing damage. In this embodiment, the instantaneous speed of the tubing string during insertion in step S2 and removal in step S4 does not exceed 15 m / min.

[0045] This drill string delivery method for casing damage detection uses a string consisting of drill pipe 1, magnetic flux leakage detection tool 2, and centralizer 3 connected sequentially from top to bottom. By replacing traditional cable delivery with drill pipe, the detection process eliminates the need for additional cables, wires, or other equipment, improving operational convenience and meeting the requirements for precise casing damage detection. It enables rapid detection of damage to the inner and outer walls of the entire well casing above the top packer during well workover operations when the tubing string is being pulled in and out.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A drill string conveying casing damage detection process string, characterized in that: The tubing string includes, from top to bottom, drill pipe, magnetic flux leakage detection tool, and centralizer, wherein: The drill pipe is used to deliver the magnetic flux leakage detection tool to the designated detection position inside the casing; The magnetic flux leakage detection tool includes a detection module, a data storage module connected to the detection module, and a motion sensing device, used to detect damage to the inner and outer walls of the casing, store detection data, and sense the lifting and lowering of the tubing. The centralizer is used to constrain the central axis of the magnetic flux leakage detection tool to be near the central axis of the tubing.

2. The drill string conveying casing damage detection process string according to claim 1, characterized in that: It also includes a guide, which is coaxially connected to the end of the stabilizer away from the magnetic flux leakage detection tool. The bottom of the guide is inclined to guide the bottom of the tubing to avoid the step inside the casing during the process of the tubing being lowered into the casing.

3. The drill string conveying casing damage detection process string according to claim 2, characterized in that: The guide is a hollow structure used to provide a fluid outlet at the bottom of the tubing string, creating a circulation channel between the tubing string and the casing annulus.

4. The drill string delivery type casing damage detection process string according to any one of claims 1-3, characterized in that: It also includes a safety connector, which is located between the magnetic flux leakage detection tool and the centralizer. When the tubing gets stuck, the pull force of the tubing reaches a preset threshold, and the tubing section below the safety connector is automatically released to unblock it.

5. A method for detecting casing damage in a drill string conveying system, characterized in that, The process string for drilling tool delivery and casing damage detection according to any one of claims 1-4 includes the following steps: S1: Pre-flush: Lower the flushing string, which is connected to the scraper and guide, into the casing section above the top packer, perform reverse circulation flushing until the returned fluid is clean, and then pull out the flushing string; S2: Running the tubing: After checking the well condition data and confirming that the maximum dogleg deviation does not exceed the maximum passability value of the magnetic flux leakage detection tool, run the tubing. S3: Data Acquisition: Set the working mode of the leakage magnetic field detection tool according to the casing damage condition, collect casing damage data through the detection module and store it in the data storage module; S4: Data playback: Remove the tubing, read the stored detection data, and analyze and judge the damage to the casing.

6. The drilling tool conveying type casing damage detection method according to claim 5, characterized in that: In step S3, the working mode includes a qualitative detection mode, in which the magnetic flux leakage detection tool is activated when the tubing is lowered, and data is collected once during the lowering and lifting of the tubing.

7. The drilling tool conveying type casing damage detection method according to claim 5, characterized in that: In step S3, the working mode includes a quantitative detection mode. In this mode, the magnetic flux leakage detection tool is set to start with a delay. Data acquisition is triggered after the tubing is lowered into place, and data is collected only during the process of lifting the tubing.

8. The drilling tool conveying type casing damage detection method according to claim 5, characterized in that: The magnetic flux leakage detection tool is equipped with a sleep mechanism and a wake-up mechanism: When the tubing is paused during insertion and the preset conditions are met, the magnetic flux leakage detection tool triggers a sleep mode. When the tubing resumes its lifting and lowering motion, the motion sensing device senses the motion and triggers a wake-up, and the magnetic flux leakage detection tool resumes data acquisition.

9. The drilling tool conveying type casing damage detection method according to claim 5, characterized in that: The instantaneous speed of the tubing in step S2 (lowering the tubing) and in step S4 (lifting the tubing) does not exceed 15 m / min.

10. The method for detecting casing damage using a drill string conveying system according to claim 5, characterized in that, In step S1, the packer is scraped up and down at least 3 times at the packer setting position, followed by a discharge rate > 50m³. 3 Reverse circulation well washing is performed under conditions of / h and pressure <5MPa until the returned fluid is clean.

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