A method for treating a cement sticking accident in a casing

Abstract

The application discloses a cement sticking accident processing method in a casing, and relates to the technical field of oil and gas drilling. First, the well section in which the drilling tool is cemented is determined; then, the non-stuck drilling tool is pulled out; the inner and outer ring teeth of the used milling ring are chamfered; then, the casing milling, back-off fishing operation is carried out by changing the way of setting the fish head; the casing milling is carried out to the corresponding position, and the up and down jarring is carried out after the downhole jarring tool is lowered and connected; the fish is pulled out, and the drilling tool cemented in the casing can be smoothly fished out of the well, so that the normal operation can be restored, the casing is not milled through and the drilling tool is not milled broken, the risk that the casing milling cylinder is stuck in the process of casing milling caused by the cement adhered to the inner wall of the casing and the fish body is prevented, and the accident loss is effectively reduced and the accident processing period is shortened.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling technology, and in particular to a method for safely, quickly and effectively handling cement stuck drill accidents inside casing. Background Technology

[0002] During drilling operations, downhole accidents may occur. In the event of a downhole accident, cement plugs are needed to correct the wellbore trajectory, avoid objects that cannot be retrieved from the bottom of the well, perform side-drilling by opening a window in the casing, or seal leaking layers. Whenever the drill bit comes into contact with cement slurry, there is a possibility that it will be solidified by the cement, causing a cement stuck drill accident.

[0003] Problems with conventional methods for handling cement stuck in the casing: 1. The fish falls to the side and is not centered, making it difficult for the milling barrel to enter the fish's head smoothly, which can easily break the fish's head and eliminate the conditions for reverse retrieval; 2. During the milling operation, cement adhering to the inner wall of the casing and the fish falls off, causing the milling barrel to get stuck; 3. When performing milling operations inside the casing, the milling ring can easily cause the casing to be milled through, making the downhole situation even worse.

[0004] In this field, "fallen fish" refers to items left in the wellbore due to various reasons, such as drill pipes, drill collars, downhole motors, drill bits, or various tools used for retrieval. To minimize losses, retrieval operations are necessary to recover as many fallen fish as possible.

[0005] In existing technologies, the conventional methods for handling cement jamming are: electrical logging, explosive cutting, and retrieving the unjammed drill string above the cutting point; milling, lowering a milling sleeve to destroy or remove the cement causing the jamming around the drill string; and reverse threading, using reverse threaded drill pipe with a reverse threaded safety connector and a reverse threaded large-head male cone to retrieve the milled drill pipe until all the stuck drill string is retrieved. However, in existing technologies, dealing with cement jamming inside the casing is very difficult because the drill string is close to one side of the casing wall, making milling very difficult and prone to milling through the casing and breaking the drill string, complicating the accident. During milling operations, cement adhering to the inner wall of the casing and the stuck drill string falls off, causing the milling sleeve to jam, further complicating the downhole situation; because the section of the well where the cement has solidified and the stuck drill string is not known, after milling the cement-solidified section, the stuck drill string falls to the bottom of the well, causing the drill string to bend, break, or deform.

[0006] In summary, the existing treatment methods are ineffective, time-consuming, and prone to complicating accidents, leading to wellbore abandonment.

[0007] The prior art includes a Chinese invention patent document with publication number CN101994496A and publication date of November 13, 1996. The technical solution disclosed in this patent document is as follows: This invention discloses a method for handling stuck pipe accidents in multi-branch horizontal wells of coalbed methane, including the following steps: calculating the location of the stuck pipe point; cleaning the inner wall of the drill pipe with a pump; lowering a sucker rod with a wireless logging-while-drilling (WWWD) retrieval head connected to its front end through the inner wall of the drill pipe; docking the WWWD retrieval head with the WWWD rig and slowly pulling out the sucker rod to remove the WWWD rig from the well; lowering a cutting tool through the inner wall of the drill pipe to the stuck pipe point and cutting the drill pipe; after cutting, removing the cutting tool and the cut free section of the drill pipe. In this embodiment of the invention, by retrieving the most economically valuable and easily retrieved components of the drilling equipment stuck downhole, the retrieval process can be stopped. This embodiment not only effectively reduces accident losses but also shortens the accident handling cycle, thus avoiding the problems of poor retrieval effect and long handling time of existing retrieval methods.

[0008] In this invention, after a stuck drill pipe accident occurs, the location of the stuck point is first determined. Then, a sucker rod with a wireless logging-while-drilling (LWD) retrieval head connected to its front end is lowered into the inner wall of the cleaned drill pipe. After the LWD retrieval head docks with the wireless LWD, the sucker rod is slowly pulled out to bring the wireless LWD out of the well. This allows the most economically valuable component of the drilling equipment stuck downhole to be retrieved. Next, a cutting tool is lowered into the inner wall of the drill pipe to a position slightly in front of the stuck point to retrieve the free section of the drill pipe. In this way, the most economically valuable and easily salvaged components of the drilling equipment stuck downhole have been retrieved from the well, allowing the salvage operation to cease. A new sidetracking wellbore trajectory can then be designed and drilled based on the location of the fish stuck in the well. This method not only effectively reduces the losses from the accident but also shortens the accident handling cycle, thus avoiding the problems of poor salvage results and long accident handling times in existing salvage methods. However, the above method cannot completely remove the drill string, and it does not solve the problem of wellbore abandonment caused by the complexity of the accident. Furthermore, it is necessary to design a new sidetracking wellbore trajectory and drill based on the location of the fish stuck in the well, which increases the workload and cost of construction. Moreover, the new sidetracking wellbore trajectory must meet both the needs of mining and the requirements of drilling technology. Many factors must be considered in the design, making it difficult to guarantee safety performance and quality, and posing certain safety hazards. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this patent proposes a method for handling cement jamming accidents inside the casing. This method not only allows the milling ring to be smoothly fitted into the fish head, but also effectively prevents the casing from being milled through and the drill bit from being broken. It also prevents the risk of the milling cylinder getting stuck due to cement adhering to the inner wall of the casing and the fish body falling off during the milling process. Furthermore, it effectively reduces accident losses and shortens the accident handling cycle, thereby avoiding the problems of poor retrieval effect and long accident handling time in existing technologies, which lead to wellbore abandonment.

[0010] This invention is achieved by adopting the following technical solution: A method for handling cement stuck drill bit accidents inside casing includes the following steps: S1. Identify the well section where the drilling tools are cemented; S2. Retrieve the unstuck drill string; S3. Chamfer the inner and outer ring teeth of the milling ring; S4. Chamfer the outer top of the lower connector of the reverse safety connector inward and connect the upper connector of the reverse safety connector. Insert the drill bit assembly consisting of the reverse large-head male cone, the reverse safety connector, and the reverse drill rod. After making a connection to the fish head, reverse open the reverse safety connector so that the fish head is the lower connector of the safety connector and acts as the guide for the milling ring to be inserted into the fish head. Perform milling and reverse docking operations. S5. Based on the cement consolidation condition, select the appropriate position for milling, then lower the downhole shock tool to reconnect and perform upper and lower shocks to release the jamming. S6. Lift the fallen fish.

[0011] Furthermore, step S1 specifically involves inserting an electrical measuring instrument into the water hole of the drill string to measure the section of the well string that has been cemented.

[0012] Furthermore, step S1 also includes using an auxiliary judgment method based on the amount of cement slurry injected and the amount of cement slurry replaced to determine the cement-consolidated well section.

[0013] Furthermore, step S2 specifically involves: using the original forward-threaded drill bit to reverse-thread and pull out the unstuck drill bit. If the reversing effect is not ideal, then re-thread it, ensuring a tight connection from top to bottom, and then use the reversing method to pull out the unstuck drill bit.

[0014] Furthermore, step S2 specifically involves: using an electrical test point to release the unstuck drill bit from above the test point after an explosive release.

[0015] Furthermore, in step S2, when the drill string is equipped with a top drive, the electrical measuring instrument is lowered from the top cover of the gooseneck tube of the top drive to connect the top drive to the drill string.

[0016] Furthermore, step S3 specifically involves: chamfering the inner teeth of the milling ring outwards and the outer teeth inwards.

[0017] Furthermore, in step S4, the milling and reverse-clamping retrieval operation is specifically as follows: while maintaining the milling parameters, the drill bit is raised and lowered to pull or pull the milling ring up 0.5m from the fish head, increasing the displacement circulation, and slowly rotating and lowering the drill bit until the milling ring fits 0.5m into the fish head. Then, the drill bit speed is increased and the drill bit is slowly lowered to 0.5m from the original milling position. The speed and displacement are reduced to the original milling parameters, and the drill bit is slowly lowered to the original milling position to continue the milling operation. A drill bit combination of reverse-clamping drill rod, reverse-clamping safety joint, and reverse-clamping large-head male cone is used. After cleaning the fish head and reverse-clamping connection, the drill bit after milling is poured out.

[0018] Furthermore, in step S4, a single milling sleeve is used, with each sleeve having a length of 1~2m.

[0019] Furthermore, in step S5, the corresponding position is a section of the well with a cement consolidation length of 0.5 to 1 m remaining, or milling to the maximum outer diameter of the bottom of the fish.

[0020] The beneficial effects of this invention are as follows: 1. This invention provides a method for handling cement-stuck drill string accidents within the casing. After a cement-stuck accident occurs, firstly, the section of the drill string solidified by cement is measured; then, the unstuck drill string is retrieved; the inner and outer teeth of the milling ring are chamfered; then, the method of inserting the "fish head" (the drill string inserted into the casing) is changed to perform milling and back-threading retrieval operations; depending on the degree of cement solidification, the milling ring is selected to the appropriate position, and a downhole shock tool is lowered for re-threading and upper and lower shocks to release the stuck drill string; finally, the "fish head" (the drill string inserted into the casing) is retrieved. In this way, the drill string solidified by cement inside the casing can be successfully retrieved from the well, thereby allowing normal construction operations to resume.

[0021] This method not only ensures that the casing is not milled through and the drill string is not broken, but also prevents the fish from being stuck to the bottom of the well during the milling process. It also prevents the milling cylinder from getting stuck due to cement falling off the inner wall of the casing and the fish body during the milling process. This avoids the problem of wellbore abandonment caused by the complication of the accident. The retrieval effect is good and can effectively reduce accident losses and shorten the accident handling cycle.

[0022] 2. This invention involves inserting an electrical measuring instrument into the water hole of the drill string to measure the cement-bonded section of the drill string. By using electrical measurement to measure the cement-bonded section of the drill string, the measurement results are more accurate.

[0023] 3. The present invention also uses the method of determining the cement-consolidated well section by the amount of cement slurry injected and the amount of cement slurry replaced. Combining the two methods to determine the consolidated well section can further obtain a more accurate cement-consolidated well section.

[0024] 4. In this invention, the original forward-locking drill bit is reversed to remove the unstuck drill bit. The earlier the reverse-locking is performed, the better. If the reverse-locking result is not ideal, it can be re-locked and the top-to-bottom tightening work is done before re-locking. This can conveniently and quickly remove the unstuck drill bit.

[0025] 5. In this invention, an electrical test point is used to release the unstuck drill bit after explosive release above the test point. Compared with the original method of using the original forward-threaded drill bit to release the unstuck drill bit, this method has a better effect. The unstuck drill bit can be released directly using this method, or it can be used after the original forward-threaded drill bit cannot be released by reversing.

[0026] 6. In this invention, when the drill string is equipped with a top drive, in order to facilitate the transmission and release of torque during electrical testing, the electrical testing instrument is lowered from the top cover of the gooseneck tube of the top drive. The top drive is connected to the drill string, and the top drive is used to transmit and release torque.

[0027] 7. In this invention, a milling ring with low tooth height and multiple teeth can be selected, and the inner and outer teeth of the milling ring are chamfered. The inner teeth of the milling ring are chamfered outward, and the outer teeth are chamfered inward, to prevent the casing from being milled through and the drill bit from being broken during the milling process.

[0028] 8. In this invention, the milling and backdeck retrieval operations are specifically as follows: Maintaining the milling parameters, raise and lower the drill bit to pull or lift the milling ring 0.5m above the fish head, increasing the flow rate for circulation. Slowly rotate and lower the drill bit until the milling ring is 0.5m inside the fish head. Increase the drill bit speed and slowly lower the drill bit to 0.5m from the original milling position. Reduce the speed and flow rate to the original milling parameters and slowly lower it to the original milling position to continue the milling operation. Use a drill bit combination of a backdeck drill rod, a backdeck safety connector, and a backdeck large-head male cone. After cleaning the fish head and backdecking, pour out the milled drill bit. Through the above steps, milling and backdeck retrieval operations can be performed efficiently and quickly.

[0029] 9. In this invention, a single milling sleeve is used, with each sleeve having a length of 1~2m, which is suitable for sleeve milling and inverted salvage operations, making sleeve milling and inverted salvage operations more efficient and faster.

[0030] 10. In this invention, based on the cement consolidation status of electrical testing and actual application, the corresponding position is the well section with 0.5~1m of cement consolidation remaining or the milling to the maximum outer diameter of the bottom of the fish. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0032] Figure 1 This is a flowchart of the processing method in Embodiment 2 of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0034] Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by one of ordinary skill in the art to which this invention pertains. The terms "comprising" or "including," and similar words used in this invention disclosure, mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] Example 1 As a preferred embodiment of the present invention, a method for handling cement stuck drill bit accidents inside casing is provided, comprising the following steps: S1. Identify the well section where the drilling tools are cemented; S2. Retrieve the unstuck drill string; S3. Chamfer the inner and outer ring teeth of the milling ring; S4. Chamfer the outer top of the lower connector of the reverse safety connector inward and connect the upper connector of the reverse safety connector. Insert the drill bit assembly consisting of the reverse large-head male cone, the reverse safety connector, and the reverse drill rod. After making a connection to the fish head, reverse open the reverse safety connector so that the fish head is the lower connector of the safety connector and acts as the guide for the milling ring to be inserted into the fish head. Perform milling and reverse docking operations. S5. Based on the cement consolidation condition, select the appropriate position for milling, then lower the downhole shock tool to reconnect and perform upper and lower shocks to release the jamming. S6. Lift the fallen fish.

[0037] This embodiment not only ensures that the casing is not milled through and the drill string is not broken, but also prevents the fish from being stuck to the bottom of the well during the milling process. It also prevents the milling cylinder from getting stuck due to cement falling off the inner wall of the casing and the fish body during the milling process. This avoids the problem of wellbore abandonment caused by the complication of the accident. The retrieval effect is good and can effectively reduce accident losses and shorten the accident handling cycle.

[0038] Example 2 As another preferred embodiment of the present invention, please refer to the appendix to the specification. Figure 1 This paper provides a method for handling cement stuck drill bit accidents inside casing, which includes the following steps: S1. Insert an electrical measuring instrument into the water hole of the drill string to measure the section of the well string that is cemented; S2. Use the original forward-threaded drill bit to reverse-thread and pull out the unstuck drill bit. The earlier the reverse-threading is done, the better. If the reverse-threading effect is not ideal, re-thread it and tighten it from top to bottom before using reverse-threading to pull out the unstuck drill bit. If several reverse-threading attempts are not ideal, use an electrical test point to loosen the thread from above the point and pull out the unstuck drill bit. S3. Chamfer the inner and outer ring teeth of the milling ring; S4. Chamfer the outer top of the lower connector of the reverse safety connector inward and connect the upper connector of the reverse safety connector. Insert the drill bit assembly consisting of the reverse large-head male cone, the reverse safety connector, and the reverse drill rod. After making a connection to the fish head, reverse open the reverse safety connector so that the fish head is the lower connector of the safety connector and acts as the guide for the milling ring to be inserted into the fish head. Perform milling and reverse docking operations. S5. Depending on the cement consolidation condition, select a section where the cement consolidation length is 0.5~1m remaining or a section where the sinker reaches its maximum outer diameter at the bottom. Then, lower downhole shock tools to reconnect the screws and perform upper and lower shocks to release the jam. S6. Lift the fallen fish.

[0039] This embodiment, based on actual usage, uses electrical logging to measure the cement-bonded section of the drill string, making the measurement results more accurate. It is also flexible, prioritizing the use of more convenient and faster methods for retrieving drill strings that are not stuck. If these methods fail, electrical logging is then used to ensure successful retrieval of the drill string. This embodiment has high applicability and can safely and quickly retrieve drill strings cement-bonded within the casing without milling through the casing or breaking the drill string, further reducing accident losses and shortening the accident handling cycle.

[0040] Example 3 As another preferred embodiment of the present invention, a method for handling cement stuck drill bit accidents inside casing is provided, comprising the following steps: S1. Insert an electrical measuring instrument into the water hole of the drill string to measure the section of the drill string that is cemented, and use the injection volume and displacement volume as auxiliary judgment methods to further determine the cemented section of the drill string. S2. Using the electrical test point, lower the electrical test instrument from the top cover of the top drive gooseneck tube to connect the top drive with the drill string. After the connection is released by explosion above the test point, remove the drill string that was not stuck. S3. Select a milling ring with low tooth height and multiple teeth, and chamfer the inner teeth of the milling ring outward and the outer teeth inward. S4. Chamfer the outer top of the lower connector of the reverse safety connector inward and connect the upper connector of the reverse safety connector. Insert the drill tool combination of reverse large-head male cone, reverse safety connector and reverse drill rod. After the fish head is connected, reverse the reverse safety connector so that the fish head is the lower connector of the safety connector as the guide for the milling ring to fit into the fish head. Use a single milling cylinder for milling. Each milling length is 1~2m. Keep the milling parameters and raise and lower the drill tool to pull or raise the milling ring 0.5m above the fish head to increase the displacement circulation. Slowly rotate and lower the drill tool until the milling ring fits into the fish head 0.5m. Increase the drill tool speed and slowly lower the drill tool to 0.5m away from the original milling position. Reduce the speed and displacement to the original milling parameters and slowly lower it to the original milling position to continue the milling operation. Use the drill tool combination of reverse drill rod, reverse safety connector and reverse large-head male cone. After cleaning and reverse connecting the fish head, pour out the drill tool after milling. S5. Based on the cement consolidation condition, select a section of the well where the cement consolidation length is 0.5~1m remaining after milling. Then, lower downhole shock tools to reconnect the clips and perform upper and lower shocks to release the jamming. S6. Lift the fallen fish.

[0041] This embodiment, based on actual usage, uses electrical logging to measure the cement-bonded section of the drill string. It employs a method that combines the injection volume and displacement volume of cement slurry to determine the cement-bonded section, resulting in a more accurate measurement. An electrical logging checkpoint is used, lowering the logging instrument from the top cover of the top drive gooseneck tube. This facilitates the transmission and release of torque during the checkpoint operation, connecting the top drive to the drill string. The drill string is then unstuck after a burst release above the checkpoint. This method is suitable for drill strings equipped with a top drive. For milling and reverse-clamping operations, a single milling sleeve is used, with each sleeve being 1-2 meters long. The specific steps involve maintaining the milling parameters, raising and lowering the drill string, or raising the milling ring 0.5 meters above the "fish head" to increase the flow rate and circulation, and slowly rotating and lowering the drill string until the milling ring fits into the "fish head". After the initial 0.5m, increase the drill string speed and slowly lower the drill string to a position 0.5m from the original milling position. Reduce the speed and displacement to the original milling parameters and slowly lower it to the original milling position to continue milling operations. Use a drill string combination of reverse-threaded drill pipe, reverse-threaded safety connector, and reverse-threaded large-head male cone. After cleaning and reverse-threading the fish head, pour out the milled drill string. Through the above steps, milling and reverse-threading retrieval operations can be performed more efficiently and quickly. In this embodiment, the fish head is inserted using low drilling pressure and intermittent rotation. At the same time, depending on the mud consolidation, select a section of the well where the cement consolidation length is 0.5~1m remaining. Run downhole shock tools to reconnect the threads and perform upper and lower shocks to release the stuck parts. This embodiment can further safely, accurately, and efficiently retrieve drill strings cemented in the casing, and can further effectively reduce accident losses and shorten the accident handling cycle.

[0042] Example 4 As another preferred embodiment of the present invention, a method for handling cement stuck drill bit accidents inside casing is provided, comprising the following steps: S1. Identify the well section where the drilling tools are cemented; S2. Use the original forward-threaded drill bit to reverse-thread and pull out the unstuck drill bit; S3. Chamfer the inner teeth of the milling ring outwards and the outer teeth inwards. S4. Chamfer the outer top of the lower connector of the reverse safety connector inward and connect the upper connector of the reverse safety connector. Lower the drill bit assembly consisting of a reverse large-head male cone, a reverse safety connector, and a reverse drill rod. After the fish head is hooked, open the reverse safety connector so that the fish head is the lower connector of the safety connector and serves as the guide for the milling ring to fit into the fish head. Maintain the milling parameters by raising and lowering the drill bit or raising the milling ring 0.5m above the fish head to increase the displacement and circulation. Slowly rotate and lower the drill bit until the milling ring fits 0.5m into the fish head. Increase the drill bit speed and slowly lower the drill bit 0.5m away from the original milling position. Reduce the speed and displacement to the original milling parameters and slowly lower it to the original milling position to continue the milling operation. Use the drill bit assembly consisting of a reverse drill rod, a reverse safety connector, and a reverse large-head male cone to clean and reverse the fish head. After the reverse connection, pour out the drill bit after milling. S5. Based on the cement consolidation condition, select the milling position to the maximum outer diameter of the bottom of the fish, and then lower the downhole shock tool to reconnect and perform upper and lower shocks to release the stuck material. S6. Lift the fallen fish.

[0043] In this embodiment, the existing forward-threaded drill bit is directly used to retrieve the unstuck drill bit using a reverse-threaded method. The milling and reverse-threading retrieval operations involve maintaining the milling parameters while raising and lowering the drill bit, or raising the milling ring 0.5m above the "fish head" (the head of the drill bit), increasing the flow rate, and slowly rotating and lowering the drill bit until the milling ring is 0.5m inside the "fish head." Then, the drill bit speed is increased, and the drill bit is slowly lowered 0.5m from the original milling position. The speed and flow rate are then reduced to the original milling parameters, and the drill bit is slowly lowered back to the original milling position to continue the milling operation. A reverse-threaded drill rod with a reverse-threaded anchor is used. The drill string assembly with a full connector and a reverse-threaded large-head male cone, after cleaning the fish head and reverse-threading the connection, allows for efficient and rapid milling and reverse-threading retrieval operations. Simultaneously, depending on the cement consolidation condition, milling is performed to the maximum outer diameter of the bottom of the fish, and a downhole shock tool is lowered to reconnect the connection before upper and lower shocks are used to release the stuck material. This embodiment enables faster retrieval of drill strings with cement consolidated inside the casing, effectively reducing accident losses and shortening the accident handling cycle.

[0044] Example 5 As another preferred embodiment of the present invention, a method for handling cement stuck drill bit accidents inside casing is provided, comprising the following steps: S1. Insert an electrical measuring instrument into the water hole of the drill string to measure the section of the well string that is cemented; S2. Use the original forward-threaded drill bit to reverse-thread and pull out the unstuck drill bit. If the reverse-threading effect is not ideal, re-thread it and tighten it from top to bottom before using reverse-threading to pull out the unstuck drill bit. S3. Select a milling ring with a lower tooth height and a larger number of teeth, and chamfer the inner teeth of the milling ring outward and the outer teeth inward. S4. Chamfer the outer top of the lower connector of the reverse safety connector inward and connect the upper connector of the reverse safety connector. Insert the drill bit assembly consisting of the reverse large-head male cone, the reverse safety connector, and the reverse drill rod. After making a connection to the fish head, reverse open the reverse safety connector so that the fish head is the lower connector of the safety connector and acts as the guide for the milling ring to be inserted into the fish head. Perform milling and reverse docking operations. S5. Depending on the cement consolidation condition, select a section of the well to be milled to where the cement consolidation length is 0.5~1m or to the maximum outer diameter of the bottom of the fish, and then lower downhole shock tools to reconnect and perform upper and lower shocks to release the stuck material. S6. Lift the fallen fish.

[0045] This embodiment, based on actual usage, uses electrical testing to measure the cement-bonded sections of the drill string, obtaining a more accurate measurement of the cement-bonded sections and making the measurement results more accurate. The original forward-threaded drill string is then reverse-threaded to retrieve the unstuck drill string. If the reverse-threading effect is unsatisfactory, it is re-threaded, ensuring a tight connection from top to bottom before retrieving the unstuck drill string using the reverse-threading method. This facilitates quick and easy retrieval of the unstuck drill string. Depending on the cement consolidation level, the casing can be milled to the appropriate position for better retrieval results. This embodiment enables safe, accurate, and efficient retrieval of drill strings cement-bonded within the casing, further effectively reducing accident losses and shortening the accident handling cycle.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for handling cement stuck drill bit accidents inside casing, characterized in that, It includes the following steps: S1. Identify the well section where the drilling tools are cemented; S2. Retrieve the unstuck drill string; S3. Chamfer the inner teeth of the milling ring outwards and the outer teeth inwards. S4. Chamfer the outer top of the lower connector of the reverse-clamp safety connector inwards and connect the upper connector of the reverse-clamp safety connector. Insert the drill bit assembly consisting of a reverse-clamp large-head male cone, a reverse-clamp safety connector, and a reverse-clamp drill pipe. After connecting the fish head to the drill bit, reverse the safety connector, so that the fish head serves as the lower connector of the safety connector as the guide for the milling ring to be inserted into the fish head. Perform milling and reverse-clamp retrieval operations. A single milling cylinder is used for milling, with each milling cycle being 1-2 meters long. The specific steps for milling and reverse-clamp retrieval operations are: maintaining... For milling, raise and lower the drill bit or raise the milling ring 0.5m above the fish head to increase the displacement circulation. Slowly rotate and lower the drill bit until the milling ring is 0.5m inside the fish head. Increase the drill bit speed and slowly lower the drill bit to 0.5m away from the original milling position. Reduce the speed and displacement to the original milling parameters and slowly lower it to the original milling position to continue milling. Use a drill bit combination of reverse-threaded drill rod, reverse-threaded safety joint, and reverse-threaded large-head male cone. After cleaning and reverse-threading the fish head, pour out the milled drill bit. S5. Depending on the cement consolidation condition, select a section to be milled to where the cement consolidation length is 0.5~1m or to the maximum outer diameter of the bottom of the fish, and then lower downhole shock tools to reconnect and perform upper and lower shocks to release the stuck material. S6. Lift the fallen fish.

2. The method for handling a cement stuck drill bit accident inside a casing according to claim 1, characterized in that, The S1 step specifically involves inserting an electrical measuring instrument into the water hole of the drill string to measure the section of the well string that has been cemented.

3. The method for handling a cement stuck drill bit accident inside a casing according to claim 2, characterized in that, Step S1 also includes using an auxiliary judgment method based on the amount of cement slurry injected and the amount of cement replaced to determine the cement-consolidated well section.

4. The method for handling a cement stuck drill bit accident inside a casing according to claim 1, characterized in that, Use the existing forward-threaded drill bit to reverse-thread and pull out the unstuck drill bit. If the reverse-threading effect is not ideal, re-thread it and tighten it from top to bottom before using the reverse-threading method to pull out the unstuck drill bit.

5. A method for handling a cement stuck drill bit accident inside a casing according to any one of claims 1-4, characterized in that, The S2 step specifically involves: using an electrical test point to release the unstuck drill bit from above the test point by explosive release.

6. A method for handling a cement jamming accident inside a casing according to claim 2 or 3, characterized in that, In step S2, when the drill string is equipped with a top drive, the electrical measuring instrument is lowered from the top cover of the top drive gooseneck tube to connect the top drive to the drill string.

Images