Process for repairing a casing of an oil and water well

Abstract

This application discloses a process for repairing casing in oil and water wells. The process includes obtaining the location and rate of diameter reduction within the casing, calculated from the deformed inner diameter and the initial inner diameter before deformation. When the rate of diameter reduction is less than or equal to a preset value, a reshaping process is used to repair the casing at the diameter reduction location. After reshaping, the repaired inner diameter is obtained. It is then determined whether the difference between the repaired inner diameter and the initial inner diameter is less than or equal to a first distance. When the difference is less than or equal to the first distance, an expansion tube process is used to repair the casing. Since the expansion tube process utilizes an expansion tube support, it can support the casing at the reshaping repair location, preventing further diameter reduction at that location and improving casing stability to ensure the repair meets the production requirements of the oil and water well.

Description

Technical Field

[0001] This application belongs to the field of oil and water well casing repair technology, specifically relating to a process method for repairing oil and water well casings. Background Technology

[0002] As oilfield development progresses to the mid-to-late stages, damage to the casing of oil and water wells becomes increasingly common. Casing repair is a specialized technique for repairing damaged casings in oil and water wells and is a crucial means of restoring normal production.

[0003] In related technologies, due to limitations in casing repair technology, repairing severely reduced-diameter casings using conventional repair processes can easily lead to accidents such as casing windowing or casing springback, resulting in poor casing repair performance that cannot meet the production needs of oil and water wells. Summary of the Invention

[0004] To address the technical problem that the repair effect of casings in related technologies is poor and cannot meet the production needs of oil and water wells, this application provides a process method for repairing casings in oil and water wells. The process method for repairing casings in oil and water wells includes:

[0005] Obtain the diameter reduction position and the diameter reduction rate of the sleeve, wherein the diameter reduction rate is calculated from the deformed inner diameter of the sleeve after deformation and the initial inner diameter of the sleeve before deformation.

[0006] When the diameter reduction ratio is less than or equal to a preset value, the sleeve is repaired by a shaping process at the diameter reduction position.

[0007] After the shaping process repairs the sleeve, the repaired inner diameter of the sleeve is obtained;

[0008] Determine whether the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance;

[0009] When the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance, the sleeve is repaired using an expansion tube process.

[0010] In some embodiments, the process for repairing oil and water well casing further includes:

[0011] When the difference between the repaired inner diameter and the initial inner diameter is greater than the first distance, determine whether the difference between the repaired inner diameter and the initial inner diameter and the first distance is less than or equal to the second distance;

[0012] When the difference between the repaired inner diameter and the initial inner diameter and the difference between the first distance are greater than the second distance, the tube sleeve is repaired using the shaping process;

[0013] When the difference between the repaired inner diameter and the initial inner diameter and the difference between the first distance and the second distance are less than or equal to the second distance, the sleeve is repaired using a milling process.

[0014] In some embodiments, before obtaining the reduced diameter location and the reduced diameter ratio within the sleeve, the method further includes:

[0015] The casing is subjected to a well-washing and pressure operation, which includes cleaning the inner wall of the casing.

[0016] In some embodiments, after performing a well-washing and pressure operation on the casing and before obtaining the reduced diameter location and the reduced diameter ratio within the casing, the method further includes:

[0017] Measure the reduced diameter position inside the sleeve, the deformed inner diameter of the sleeve after deformation, and the initial inner diameter of the sleeve before deformation.

[0018] In some embodiments, the shaping construction column used in the shaping process includes a shaping column, a first expansion head, and a weight indicator, wherein the first expansion head and the weight indicator are respectively connected to the shaping column; the shaping process includes:

[0019] The first expansion head is lowered to the reduced diameter position along the extension direction of the sleeve;

[0020] Continue to lower the first expansion head until the weight indicator displays zero;

[0021] The shaping construction column is pressurized until the first expansion head can pass through the reduced diameter position.

[0022] In some embodiments, a plurality of balls are provided on the periphery of the first expansion head, the balls protruding from the periphery of the first expansion head and rotatably connected to the first expansion head; the step of lowering the first expansion head to the reduced diameter position along the extension direction of the sleeve includes:

[0023] Place the first expansion head into the sleeve, so that the ball is slidably connected to the inner wall of the sleeve;

[0024] The first expansion head is lowered to the reduced diameter position along the extension direction of the sleeve.

[0025] In some embodiments, pressurizing the shaping construction string until the first expansion head can pass through the reduced diameter position includes:

[0026] Apply the first pressure to the shaping construction column and lower the first expansion head until the weight indicator shows zero.

[0027] The second pressure is applied repeatedly to the shaping construction column until the first expansion head passes through the reduced diameter position.

[0028] In some embodiments, after lowering the first bulge to the reduced diameter position along the extension direction of the sleeve, the method further includes...

[0029] The first expansion head is replaced with the second expansion head, and the difference between the outer diameter of the second expansion head and the outer diameter of the first expansion head is greater than or equal to a preset outer diameter difference.

[0030] The second expansion head is lowered along the extension direction of the sleeve to the reduced diameter position;

[0031] Continue lowering the second expansion head until the weight indicator displays zero;

[0032] The shaping construction column is pressurized until the second expansion head passes through the reduced diameter position.

[0033] In some embodiments, the expansion tube process uses an expansion construction string including an expansion tube and a weight indicator connected to the expansion tube, and the expansion tube process includes:

[0034] Lower the expansion tube to the reduced diameter position;

[0035] The expansion tube is pressurized to expand it until it fits against the inner wall of the sleeve.

[0036] In some embodiments, the step of pressurizing the shaping construction string until the second expansion head passes the reduced diameter position further includes:

[0037] Determine whether the expansion string can be lifted to start the operation;

[0038] If not, increase the auxiliary lifting load of the expansion tube or reduce the thickness of the expansion tube.

[0039] According to one or more embodiments of this application, a process method for repairing casing in oil and water wells includes obtaining the reduced diameter location and the reduced diameter ratio within the casing. The reduced diameter ratio is calculated from the deformed inner diameter of the casing after deformation and the initial inner diameter before deformation. When the reduced diameter ratio is less than or equal to a preset value, a reshaping process is used to repair the casing at the reduced diameter location. After the reshaping process repairs the casing, the repaired inner diameter of the casing is obtained. It is determined whether the difference between the repaired inner diameter and the initial inner diameter is less than or equal to a first distance. When the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance, an expansion tube process is used to repair the casing. Since the expansion tube process utilizes an expansion tube patching process, an expansion tube can be used to support the casing at the reshaping repair location. This prevents the casing from shrinking again at the reshaping repair location, improving the stability of the casing and ensuring that the repair effect meets the production needs of the oil and water well. Attached Figure Description

[0040] Figure 1 A flowchart illustrating a process for repairing casing in oil and water wells, provided for one or more embodiments of this application;

[0041] Figure 2 Another flowchart of a process for repairing casing in oil and water wells, provided for one or more embodiments of this application. Detailed Implementation

[0042] To enable those skilled in the art to more clearly understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0043] As oilfield development progresses into its mid-to-late stages, casing damage in oil and water wells becomes increasingly common. This damage not only directly impacts the normal production of oil and water wells but also affects adjacent wells, potentially causing regional casing damage and significant losses. Casing repair is a specialized technique for repairing damaged casings in oil and water wells and is a crucial means of restoring normal production.

[0044] In related technologies, due to limitations in casing repair technology, repairing severely reduced-diameter casings using conventional repair processes can easily lead to accidents such as casing windowing or casing springback, resulting in poor casing repair performance that cannot meet the production needs of oil and water wells.

[0045] In order to solve the technical problem that the repair effect of the sleeve in the related technology is poor and cannot meet the production needs of oil and water wells, this application provides a process method for repairing the casing of oil and water wells.

[0046] Please see Figure 1 , Figure 1 A flowchart of a process for repairing casing in oil and water wells, provided for one or more embodiments of this application.

[0047] like Figure 1 As shown, the process for repairing oil and water well casing includes at least the following:

[0048] S102. Obtain the diameter reduction position and the diameter reduction rate of the sleeve.

[0049] During oil and water well production, if the production tool encounters an obstruction and gets stuck inside the casing while being lowered along the casing to the designated working position inside the well, it can be determined that the casing has narrowed. The reduced diameter at the narrowing location prevents the production tool from passing through and causes it to become stuck inside the casing.

[0050] When a reduction in diameter is identified within the pipe sleeve, measuring tools can be used to measure the deformed inner diameter of the sleeve after deformation and its initial inner diameter before deformation (i.e., the actual inner diameter of the sleeve, which can also be obtained from relevant documents). The reduction rate is calculated from the deformed inner diameter and the initial inner diameter before deformation. Specifically, the difference between the initial inner diameter and the deformed inner diameter is the deformation of the sleeve's inner diameter, and the ratio of the deformation to the initial inner diameter before deformation is the reduction rate. Based on the obtained location of the reduction in diameter, the pipe sleeve repair tool can be directly lowered to the reduction location to repair the sleeve, improving the repair efficiency and accuracy.

[0051] S104. When the diameter reduction ratio is less than or equal to a preset value, the sleeve is repaired by a shaping process at the diameter reduction position.

[0052] To ensure the quality of pipe sleeve repair, a corresponding repair process needs to be selected based on the pipe sleeve's diameter reduction ratio. Specifically, the pipe sleeve's diameter reduction ratio is compared with a preset value. When the pipe sleeve's diameter reduction ratio is less than or equal to the preset value, the diameter reduction area within the pipe sleeve can be repaired using a reshaping process. Pipe sleeves are typically made of steel, and the preset value can be determined based on a combination of factors, including the steel grade used to make the pipe sleeve, the wall thickness of the pipe sleeve, the tightening quality of the pipe sleeve, and the surface pressure. A preset value of 20% is typically used. When the pipe sleeve's diameter reduction ratio is less than or equal to 20%, a reshaping process is used to repair the diameter reduction area within the pipe sleeve.

[0053] It should be noted that the sleeve can also be made of other materials, and the specific design can be determined according to actual needs. This application does not impose any restrictions.

[0054] S106. After the shaping process repairs the sleeve, obtain the repaired inner diameter of the sleeve.

[0055] The shaping process typically involves repeatedly tapping the expansion head at the reduced diameter position under a set pressure, allowing the expansion head to pass through the reduced diameter position inside the sleeve. This repairs the reduced diameter position of the sleeve, increasing its inner diameter, so that production tools can pass through the reduced diameter position.

[0056] After repairing the reduced diameter position inside the sleeve using an expansion head with the required outer diameter, the repaired inner diameter of the sleeve is obtained using a measuring tool. This allows for a more accurate determination of the sleeve's repair status after the shaping process.

[0057] S108. Determine whether the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance.

[0058] S110. When the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance, the sleeve is repaired using an expansion tube process.

[0059] Depending on the material used to manufacture the sleeve, its stability varies. For sleeves with resilience, after reshaping and repair, the sleeve will shrink again at the repair site, causing production tools to become stuck inside the sleeve and unable to pass through.

[0060] The difference between the measured repair inner diameter and the initial inner diameter before casing deformation is calculated, and it is determined whether the difference is less than or equal to a first distance. When the difference between the repair inner diameter and the initial inner diameter before casing deformation is less than or equal to the first distance, the casing is repaired using an expansion tube process. The expansion tube process utilizes an expansion tube to support the casing at the repair location, preventing the casing from shrinking again at the repair location, improving the stability of the casing, and ensuring that the repair effect meets the production needs of oil and water wells.

[0061] It should be noted that since the expansion tube used in the expansion tube process occupies the inner diameter of the sleeve, the initial distance needs to be determined based on the passage space for the production tools and the size of the inner diameter occupied by the expansion tube in the sleeve. This ensures that the shaping and repair position within the sleeve can be used for expansion tube process repair while also allowing the production tools to pass through the expansion tube. This ensures both the stability of the sleeve and the normal passage of the production tools within it.

[0062] This application also provides a process method for repairing casing in oil and water wells. Please refer to [link / reference]. Figure 2 , Figure 2 Another flowchart of a process for repairing casing in oil and water wells, provided for one or more embodiments of this application.

[0063] like Figure 2 As shown, the process for repairing oil and water well casing includes at least the following:

[0064] S202. Perform a well-washing and pressure-up operation on the casing, the well-washing and pressure-up operation including cleaning the inner wall of the casing.

[0065] During the production process of oil and water wells, if the production tool encounters an obstacle and gets stuck inside the casing while being lowered along the casing to the designated working position inside the well, it can be determined that the casing has narrowed. The diameter of the casing at the narrowing position is smaller, causing the production tool to be unable to pass and get stuck inside the casing.

[0066] When a reduction in diameter is detected within the casing, a well-washing and pressure operation is performed on the casing. This operation includes cleaning the inner wall of the casing. Specifically, cleaning the inner wall of the casing ensures that it is relatively clean, facilitating subsequent repairs of the reduced diameter area and improving the quality and convenience of such repairs.

[0067] S204. Measure the reduced diameter position inside the sleeve, the deformed inner diameter of the sleeve after deformation, and the initial inner diameter of the sleeve before deformation.

[0068] After the inner wall of the casing is thoroughly cleaned, measuring tools can be used to measure the location of the inner diameter reduction, the deformed inner diameter after deformation, and the initial inner diameter before deformation. Specifically, downhole television or multi-arm caliper instruments can be used to diagnose the condition inside the casing, determining the location of the inner diameter reduction, the deformed inner diameter after deformation, and the initial inner diameter before deformation. Because the inner wall of the casing is relatively clean, the accuracy of measuring the location of the inner diameter reduction, the deformed inner diameter after deformation, and the initial inner diameter before deformation can be improved.

[0069] To maintain pressure balance within the casing, after obtaining the reduced diameter, deformed inner diameter, and initial inner diameter, kill fluid can be injected into the casing to maintain pressure balance, prevent overflow during repair, and improve the safety of the repair. It should be noted that the kill fluid can be clean water or other liquids; this application does not limit its use and it can be selected according to actual needs.

[0070] S206. Obtain the diameter reduction position and the diameter reduction rate of the sleeve.

[0071] Please refer to step S102, which will not be repeated here.

[0072] S208. When the diameter reduction ratio is less than or equal to a preset value, the sleeve is repaired by a shaping process at the diameter reduction position.

[0073] To ensure the quality of pipe sleeve repair, a corresponding repair process needs to be selected based on the pipe sleeve's diameter reduction ratio. Specifically, the pipe sleeve's diameter reduction ratio is compared with a preset value. When the pipe sleeve's diameter reduction ratio is less than or equal to the preset value, the diameter reduction area within the pipe sleeve can be repaired using a reshaping process. Pipe sleeves are typically made of steel, and the preset value can be determined based on a combination of factors, including the steel grade used to make the pipe sleeve, the wall thickness of the pipe sleeve, the tightening quality of the pipe sleeve, and the surface pressure. A preset value of 20% is typically used. When the pipe sleeve's diameter reduction ratio is less than or equal to 20%, a reshaping process is used to repair the diameter reduction area within the pipe sleeve.

[0074] It should be noted that the sleeve can also be made of other materials, and the specific design can be determined according to actual needs. This application does not impose any restrictions.

[0075] The shaping process can utilize hydraulic shaping. The shaping construction string used in the process includes a shaping string, a first expansion head, and a weight indicator. The first expansion head and the weight indicator are connected to the shaping string, with the first expansion head located below it. The shaping process includes: lowering the first expansion head along the extension direction of the sleeve to the reduced diameter position, continuously lowering the first expansion head until the weight indicator displays zero, and pressurizing the shaping construction string until the first expansion head can pass through the reduced diameter position.

[0076] Specifically, during the initial shaping of the casing using the forming process, a first expansion head with a maximum outer diameter 4mm larger than the deformed inner diameter of the casing and a 700-type pump truck can be used to provide hydraulic pressure. When the high-pressure pipeline connected to the forming tubing is energized, the forming tubing can be lowered along the extension direction of the casing, lowering the first expansion head to the reduced diameter position. The forming tubing continues to be lowered; when the first expansion head contacts the reduced diameter position inside the casing, the weight indicator will show resistance. Using the weight of the forming tubing, the first expansion head is repeatedly lowered until the weight indicator shows zero (the position where the weight indicator shows zero can be recorded as the resistance position). At this point, all the weight of the forming tubing is pressed against the resistance position. Hydraulic pressure can then be applied to the forming tubing to increase the pressure of the first expansion head impacting the reduced diameter position, allowing the first expansion head to pass through the reduced diameter position.

[0077] It should be noted that a plurality of rolling balls are provided on the periphery of the first expansion head, the rolling balls protruding from the periphery of the first expansion head and rotatably connected to the first expansion head. Lowering the first expansion head along the sleeve to the reduced diameter position specifically includes: placing the first expansion head inside the sleeve, causing the rolling balls to slide against the inner wall of the sleeve, and lowering the first expansion head to the reduced diameter position along the extending direction of the sleeve.

[0078] Specifically, high-strength steel balls are arranged on the outer side of the first expansion head. The highest point of the outer surface of the steel balls is typically 4mm higher than the outer surface of the first expansion head, allowing the steel balls to protrude from the first expansion head and slide against the inner wall of the sleeve. At least four rings of steel balls can be evenly spaced along the axial direction of the first expansion head, with a distance of 80mm between adjacent rings. Since the steel balls can slide against the inner wall of the sleeve through rotation, the relative movement of the first expansion head against the inner wall of the sleeve improves the smoothness of its movement within the sleeve, preventing the forming tube from getting stuck and ensuring that the forming process can be performed within the sleeve to repair it.

[0079] Pressurizing the shaping construction pipe column until the first expansion head can pass through the reduced diameter position specifically includes: applying a first pressure to the shaping construction pipe column, lowering the first expansion head until the weight indicator shows zero; and repeatedly applying a second pressure to the shaping construction pipe column until the first expansion head passes through the reduced diameter position.

[0080] Specifically, the initial pressure for the initial pressurization of the shaping construction tubing can be 10 MPa. After stabilizing the pressure for 5 minutes, the shaping tubing is raised and then lowered until the weight indicator shows zero. The second pressure is increased to the shaping construction tubing multiple times, with each increase being 5 MPa. The total pressurization pressure should not exceed 25 MPa. The shaping tubing is then lowered until the first expansion head can pass through the reduced diameter position inside the tubing sleeve.

[0081] To determine the effectiveness of the shaping process, a mark is made at a suitable position where the shaping string extends above the ground when it is first lowered along the extension direction of the casing until the weight indicator reads zero. The shaping string is then pressurized and lowered again until the weight indicator reads zero. If the marked position of the string extending above the ground moves downwards, the shaping process is effective; if the marked position remains unchanged, the shaping process is ineffective.

[0082] It should be noted that the shaping effect of the shaping process after each pressing can be known by marking before and after each pressing and observing the downward movement of the marked positions.

[0083] After the first expansion head passes through the reduced diameter position inside the sleeve, the shaping tube is removed from the sleeve, and the first expansion head is replaced with a second expansion head. The difference between the outer diameter of the second expansion head and the outer diameter of the first expansion head is greater than or equal to a preset outer diameter difference. The second expansion head is lowered along the extension direction of the sleeve to the reduced diameter position. The second expansion head is lowered until the weight indicator shows zero. The shaping construction tube is pressurized until the second expansion head passes through the reduced diameter position.

[0084] Depending on the on-site pipe sleeve shaping conditions, the outer diameter of the second expansion head can be selected such that the difference between its outer diameter and that of the first expansion head is greater than or equal to a preset outer diameter difference, typically 2mm to 4mm. Using the second expansion head for the shaping process, lower it along the extension direction of the pipe sleeve to the reduced diameter position; continue lowering the second expansion head until the weight indicator shows zero (the position where the weight indicator shows zero can be recorded as the obstruction position). At this point, all the weight of the shaping construction pipe string is pressed against the obstruction position. Hydraulic pressure can then be applied to the shaping construction pipe string to increase the pressure of the second expansion head impacting the reduced diameter position, allowing the second expansion head to pass through the reduced diameter position. The shaping capacity of each expansion head should be controlled within a range of 2mm to 4mm increase compared to the previous expansion head. Small changes in the outer diameter of the expansion heads can prevent the shaping pipe string from getting stuck inside the pipe sleeve. Depending on the shaping requirements of the sleeve, the sleeve can be shaped by replacing the third, fourth, and fifth expansion heads until the outer diameter of the expansion head is 6mm to 8mm smaller than the inner diameter of the sleeve. The hydraulic shaping of the sleeve is then complete, and the shaped tubing can be removed from the sleeve. The gradually increasing outer diameter of different expansion heads expands the shaping range of the process to accommodate various diameter reductions within the sleeve, thus improving the applicability of the shaping process.

[0085] The forming process employs a hydraulic forming technique. When the forming construction string is placed inside the casing along its extension direction, the forming construction string, from bottom to top, includes a first expansion head, a hydraulic cylinder, a hydraulic anchor, a lift-type oil drain, a filter short section, a lifting short section, a ball-operated pressure-pressurized safety joint, and a weight indicator. The forming string is connected to the upper part of the ball-operated pressure-pressurized safety joint, and the weight indicator is connected to the outer side of the first expansion head. The maximum outer diameter of the ball-operated pressure-pressurized safety joint can be set to be 4mm smaller than the maximum outer diameter of the first expansion head. Steps should be avoided at the connection points of adjacent components in the forming construction string to prevent the forming construction string from getting stuck during its descent along the casing. This allows the forming construction string to be smoothly lowered along the casing's axis to the inner diameter reduction position for casing repair.

[0086] It should be noted that when the diameter reduction rate of the sleeve is determined to be less than or equal to 20%, the sleeve can be repaired first by mechanical shaping process at the diameter reduction position inside the sleeve. By using the weight of the shaping tube string, it is gently moved up and down several times. If the shaping tube string still cannot pass through the diameter reduction position inside the sleeve after three rounds of back and forth, then hydraulic shaping process can be used.

[0087] S210. After the shaping process repairs the sleeve, obtain the repaired inner diameter of the sleeve.

[0088] Please refer to step S106, which will not be repeated here.

[0089] S212. Determine whether the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance.

[0090] Please refer to step S108, which will not be repeated here.

[0091] S214. When the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance, the sleeve is repaired using an expansion tube process.

[0092] Depending on the material used to manufacture the sleeve, its stability varies. For sleeves with resilience, after reshaping and repair, the sleeve will shrink again at the repair site, causing production tools to become stuck inside the sleeve and unable to pass through.

[0093] To prevent the sleeve from shrinking again at the repair location during the shaping process, an expansion tube process is used to repair the sleeve when the difference between the repaired inner diameter and the initial inner diameter is less than or equal to a first distance. The expansion tube process utilizes an expansion tube support at the repair location during the shaping process to prevent the sleeve from shrinking again and improve its stability.

[0094] It should be noted that since the expansion tube used in the expansion tube process occupies the inner diameter of the sleeve, the initial distance needs to be determined based on the passage space for the production tools and the size of the inner diameter occupied by the expansion tube in the sleeve. This ensures that the shaping and repair position within the sleeve can be used for expansion tube process repair while also allowing the production tools to pass through the expansion tube. This ensures both the stability of the sleeve and the normal passage of the production tools within it.

[0095] The expansion tube process uses an expansion construction column, including an expansion tube and a weight indicator. The expansion tube process includes: lowering the expansion tube to the reduced diameter position, pressurizing the expansion tube, and expanding the expansion tube until it fits against the inner wall of the sleeve.

[0096] Specifically, the hydraulic pressure for the expansion joint can be provided by a 700-type pump truck, and the pressure resistance of the high-pressure pipeline used is greater than or equal to 50MPa. Since the expansion tube process requires occupying the inner diameter of the casing, the order of patching the expansion tube to the inner wall of the casing using the expansion tube process needs to be from bottom to top along the extension direction of the casing.

[0097] The expansion construction string may also include a retrieval-type bottom plug, a pressure-pressurizing ascending connector, and tubing. When the expansion construction string is placed inside the casing for expansion tube process repair of the casing, the expansion construction string may include, from bottom to top, a retrieval-type bottom plug, the expansion string, the pressure-pressurizing ascending connector, and tubing along the extension direction of the casing. The weight indicator is connected to the expansion string, and the end of the tubing can extend into the expansion string.

[0098] The expansion tube process includes: lowering the expansion tube string to the reduced-diameter position inside the casing (the position to be fitted), connecting the ground pressure testing line and starting the 700-type pump truck. The expansion tube string begins pressure testing, causing the expansion tube to expand. At this time, the hook of the crane connected to the expansion tube string and used to lift the expansion tube string is stable, ensuring the position of the expansion tube string inside the casing is determined. When the pressure testing pressure of the expansion tube string reaches 25 MPa, the expansion tube string drives the expansion tube to expand, causing the expansion tube to fit against the inner wall of the casing. The friction between the expansion tube and the casing increases, and the reading of the weight indicator decreases.

[0099] After the expansion tube has moved 0.5m along the extension direction of the sleeve, lift the expansion tube until it is at its original suspended weight and remains unchanged. This indicates that the lower end of the expansion tube has been firmly attached to the inner wall of the sleeve, which can also provide anchoring force for continuing to pressurize the expansion tube.

[0100] Determine whether the expansion tube can be lifted to start. If not, increase the auxiliary lifting load of the expansion tube or reduce the thickness of the expansion tube.

[0101] Specifically, when the expansion string is being fitted into the corresponding position within the casing, the crane hook needs to lift the expansion string along the extension direction of the casing to move it to the desired position. Typically, the starting pressure of the expansion string is less than or equal to 25 MPa, and the auxiliary load of the crane hook is less than or equal to 20 t. That is, the starting pressure of the expansion string is usually 25 MPa, which is sufficient to lift it along the extension direction of the casing. However, due to the resistance encountered by the expansion string during lifting, if the starting pressure exceeds 25 MPa, the lifting force of the crane hook can be increased as needed to lift the expansion string along the extension direction of the casing within the expansion tube. Alternatively, reducing the wall thickness of the expansion tube can reduce the resistance encountered within it, lowering the lifting force and ensuring the expansion string can be lifted along the extension direction of the casing within the expansion tube, thus reducing the difficulty of starting the expansion string. Continue raising the expansion string to the position where the expansion tube needs to be fitted, and pressurize the expansion string to fit the reduced diameter position inside the casing. Continue raising the expansion string along the extension direction of the casing, ensuring the weight indicator reading is near the original suspended weight of the expansion string, guaranteeing the expansion tube is fitted to the reduced diameter position inside the casing. When the pressure on the weight indicator drops to zero, it indicates the expansion string has disengaged, and the expansion tube is fully fitted to the reduced diameter position inside the casing. At this point, the expansion string can be removed from the casing, completing the expansion tube process. The expansion tube process utilizes the expansion tube fitting technique to support the casing at the repaired position during the casing reshaping process, preventing the casing from shrinking again and improving its stability.

[0102] After the pipe sleeve is repaired using the expansion tube process, its sealing performance needs to be tested. The test pressure is 15 MPa, and after standing for 30 minutes, the pressure drop inside the pipe sleeve is measured using a pressure gauge. If the pressure drop inside the pipe sleeve is less than 0.5 MPa, it indicates that the pipe sleeve has good sealing performance and the repair of the reduced diameter area inside the pipe sleeve is relatively complete.

[0103] S216. When the difference between the repaired inner diameter and the initial inner diameter is greater than the first distance, determine whether the difference between the repaired inner diameter and the initial inner diameter and the first distance is less than or equal to the second distance.

[0104] For resilient casing, after the casing is repaired using a shaping process, a well gauge is used to measure the repaired inner diameter of the casing, which should be 6mm to 8mm smaller than the original inner diameter. If the well gauge can pass through the reduced diameter area after the shaping process, the casing repair is successful. If the well gauge cannot pass through the reduced diameter area, it indicates that the reduced diameter area repaired by the shaping process has rebounded. In other words, the casing has reduced its diameter again at the repaired location, and the difference between the repaired inner diameter and the initial inner diameter is greater than the first distance, causing the production tool to become stuck inside the casing.

[0105] S218. When the difference between the repaired inner diameter and the initial inner diameter before deformation of the sleeve and the difference between the first distance are greater than the second distance, the sleeve is repaired using the shaping process.

[0106] Depending on the actual situation, the second distance can be set to 4mm. If the difference between the repaired inner diameter and the initial inner diameter and the difference between the first distance are less than or equal to 4mm, it indicates that the sleeve rebound is relatively serious, and the sleeve needs to be repaired again using the reshaping process (or the sleeve needs to be repaired multiple times using the reshaping process) until the difference between the repaired inner diameter and the initial inner diameter before the sleeve deformation and the difference between the first distance are less than or equal to 4mm.

[0107] S220. When the difference between the repaired inner diameter and the initial inner diameter before the deformation of the sleeve and the difference between the first distance and the second distance are less than or equal to the second distance, the sleeve is repaired by milling.

[0108] If the difference between the repaired inner diameter and the initial inner diameter before deformation of the sleeve and the difference between the first distance are less than or equal to 4mm, it indicates that the sleeve has low resilience and the sleeve can be repaired by grinding and milling.

[0109] The milling process uses a milling string consisting of at least a milling string and a milling cone, connected to the milling cone via a safety joint. When the milling string is placed inside the casing for casing repair, the milling cone, safety joint, and milling string are arranged sequentially from bottom to top, with the maximum outer diameter of the safety joint being less than or equal to the maximum outer diameter of the milling cone. A power swivel or hydraulic rotary table can be used to provide rotational power for the milling string, while a 400-type or 700-type pump truck provides the power for well workover fluid circulation using a positive circulation method. The outer diameter of the milling cone is typically set 6mm smaller than the inner diameter of the casing, ensuring that the inner diameter of the reduced-diameter area after milling is close to the initial inner diameter. This provides ample repair space for casing repair and prevents casing leakage, thus avoiding casing windowing. When the milling and milling process can pass through the reduced diameter position without pressure or rotation of the milling cone, it indicates that the milling and milling of the reduced diameter position of the pipe sleeve is complete. Then, the expansion tube process can be used to repair and reinforce the reduced diameter pipe sleeve, thereby improving the stability of the pipe sleeve.

[0110] In the milling process, multiple milling cones with different outer diameters can be used to mill the diameter reduction position. The outer diameters of different milling cones gradually increase, which can expand the milling range of the milling process to meet the needs of various diameter reductions in the pipe sleeve and improve the applicability of the milling process.

[0111] It should be noted that for resilient pipe sleeves, the forming process, milling process, and expansion tube process can be used sequentially to repair the sleeves. The repair process can be adjusted according to the needs of the site conditions. The repair process is safe, controllable, and highly adaptable. The forming, milling, and expansion tube processes are simple to operate, reducing repair costs while improving repair efficiency. Furthermore, the equipment used for these processes is simple in structure, small in size, has short construction time, and high operational efficiency, thus improving the overall efficiency of pipe sleeve repair.

[0112] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0113] In the description of this application, 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", and "counterclockwise" 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 application 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 application.

[0114] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0115] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0116] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A process for repairing casing in oil and water wells, characterized in that, include: Obtain the diameter reduction position and the diameter reduction rate of the sleeve, wherein the diameter reduction rate is calculated from the deformed inner diameter of the sleeve after deformation and the initial inner diameter of the sleeve before deformation. When the diameter reduction ratio is less than or equal to a preset value, the sleeve is repaired by a shaping process at the diameter reduction position. After the shaping process repairs the sleeve, the repaired inner diameter of the sleeve is obtained; Determine whether the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance; When the difference between the repaired inner diameter and the initial inner diameter is less than or equal to the first distance, the sleeve is repaired using an expansion tube process; When the difference between the repaired inner diameter and the initial inner diameter is greater than the first distance, the reduced diameter position repaired by the shaping process inside the sleeve rebounds. It is then determined whether the difference between the repaired inner diameter and the initial inner diameter and the first distance is less than or equal to the second distance. When the difference between the repaired inner diameter and the initial inner diameter and the difference between the first distance are greater than the second distance, the tube sleeve is repaired using the shaping process; When the difference between the repaired inner diameter and the initial inner diameter and the difference between the first distance and the second distance are less than or equal to the second distance, the sleeve is repaired using a milling process.

2. The process method for repairing oil and water well casing according to claim 1, characterized in that, Before obtaining the reduced diameter location and the reduced diameter ratio within the sleeve, the method further includes: The casing is subjected to a well-washing and pressure operation, which includes cleaning the inner wall of the casing.

3. The process method for repairing oil and water well casing according to claim 2, characterized in that, After performing the well-washing and pressure operation on the casing, and before obtaining the reduced diameter location and the reduced diameter ratio within the casing, the process further includes: Measure the reduced diameter position inside the sleeve, the deformed inner diameter of the sleeve after deformation, and the initial inner diameter of the sleeve before deformation.

4. The process method for repairing oil and water well casing according to claim 1, characterized in that, The shaping process uses a shaping construction column comprising a shaping column, a first expansion head, and a weight indicator, wherein the first expansion head and the weight indicator are respectively connected to the shaping column; the shaping process includes: The first expansion head is lowered to the reduced diameter position along the extension direction of the sleeve; Continue to lower the first expansion head until the weight indicator displays zero; The shaping construction column is pressurized until the first expansion head can pass through the reduced diameter position.

5. The process method for repairing oil and water well casing according to claim 4, characterized in that, The first expansion head is provided with a plurality of rolling balls on its periphery, the rolling balls protruding from the periphery of the first expansion head and rotatably connected to the first expansion head; The step of lowering the first expansion head along the extension direction of the sleeve to the reduced diameter position includes: Place the first expansion head into the sleeve, so that the ball is slidably connected to the inner wall of the sleeve; The first expansion head is lowered to the reduced diameter position along the extension direction of the sleeve.

6. The process method for repairing oil and water well casing according to claim 4, characterized in that, The pressurization of the shaped construction pipe column until the first expansion head can pass through the reduced diameter position includes: Apply the first pressure to the shaping construction column and lower the first expansion head until the weight indicator shows zero. The second pressure is applied repeatedly to the shaping construction column until the first expansion head passes through the reduced diameter position.

7. The process method for repairing oil and water well casing according to claim 4, characterized in that, After lowering the first expansion head to the reduced diameter position along the extension direction of the sleeve, the method further includes: The first expansion head is replaced with the second expansion head, and the difference between the outer diameter of the second expansion head and the outer diameter of the first expansion head is greater than or equal to a preset outer diameter difference. The second expansion head is lowered along the extension direction of the sleeve to the reduced diameter position; Continue lowering the second expansion head until the weight indicator displays zero; The shaping construction column is pressurized until the second expansion head passes through the reduced diameter position.

8. The process method for repairing oil and water well casing according to claim 1, characterized in that, The expansion pipe process uses an expansion pipe column, which includes an expansion pipe column and a weight indicator connected to the expansion pipe column. The expansion pipe process includes: Lower the expansion tube to the reduced diameter position; The expansion tube is pressurized to expand it until it fits against the inner wall of the sleeve.

9. The process method for repairing oil and water well casing according to claim 7, characterized in that, The step of pressurizing the shaped construction pipe column until the second expansion head passes the reduced diameter position further includes: Determine whether the expansion string can be lifted to start the operation; If not, increase the auxiliary lifting load of the expansion tube or reduce the thickness of the expansion tube.

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