Circulation connector and underground fault processing device and method

Abstract

The invention provides a circulating connector and an underground fault processing device and method.The underground fault processing device comprises an outer combination tool string and an inner combination tool string, and the outer combination tool string comprises a milling head, a milling pipe, a two-stage buckling connector and a safety connector which are sequentially arranged from bottom to top; the inner combination tool string comprises a fishing tool, a back pressure valve and a circulating connector which are sequentially arranged from bottom to top, the inner combination tool string is located in the milling pipe, the circulating connector is connected with the two-stage buckling connector, the circulating connector comprises a body, a main water hole and a side water hole, the main water hole is formed in the central axis direction of the body, and the side water hole is formed in the body. The side water hole is formed in the side wall of the body and communicated with the main water hole. The underground fault processing device can also comprise a fishing tool, a safety connector, a back pressure valve and a circulating connector which are sequentially arranged from bottom to top. The underground fault processing method can be realized through the two underground fault processing devices. When the device is used for salvaging the fallen fish, circulation can be established, and the well control risk is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of downhole fault treatment. Specifically, it relates to a circulation joint, a downhole fault treatment device and a method. Background Art

[0002] During drilling operations, downhole faults often occur. When dealing with downhole faults, the existing fishing string for fishing lost fish generally has only one water eye for circulation. When fishing for lost fish during drilling operations, most of the operations are carried out in the open hole section. When fishing for lost fish during workover operations, it is generally carried out in the casing. Many old well lost fish are buried, and there are also cases in the open hole section. When fishing for lost fish, the existing fishing technology requires the pump to be stopped. If the formation above the fish head in the open hole section collapses at this time, the fishing string will be buried. Once the fishing string is buried, the fishing work becomes complicated. In most cases, the water eye of the downhole fish is blocked. When the downhole fish is caught, since circulation cannot be established, the formation fluid in the oil and gas layer section enters the wellbore and accumulates in the buried drill string section, posing a well control risk during lifting. Once a well control accident occurs, only the method of reverse well control can be used to push the formation fluid and impurities back into the formation, which affects the oil and gas production effect and complicates the fault treatment work.

[0003] Currently, when dealing with downhole faults by conventional fishing, the operation needs to be carried out with the pump stopped. The collapse of the formation in the easily collapsible formation section of the open hole above the lost fish will cause stuck pipe due to collapse, such as when a casing fishing integrated tool is stuck, which is difficult to handle, has a long cycle, high comprehensive cost, high risk, and may even cause the wellbore to be abandoned and sidetracked in severe cases, with a large negative impact and being unfavorable for improving quality and efficiency. Especially after a downhole fault occurs in the oil and gas layer, the oil and gas at the bottom of the well accumulate. After fishing for the lost fish, since the water eye of the lost fish is blocked, the oil and gas accumulated at the bottom of the well cannot be circulated out in time, and the well control risk is very high. Once a well control accident occurs, although the well control accident can be relieved by the reverse well control method, harmful solids are also pressed into the oil and gas layer during reverse well control, blocking the oil and gas channels and affecting the subsequent production effect. Therefore, it is of great significance to provide a circulation joint, a downhole fault treatment device and a method.

[0004] Chinese Patent with the application number "CN202010253038.5" and the name "Fishing Tool" discloses a fishing tool. The tool includes a cylinder body, the cylinder body includes a first end and a second end arranged opposite to each other. The first end of the cylinder body is an upper joint, and the second end of the cylinder body is detachably connected with a lost object receiving port; wherein, a sealing cylinder is arranged on the inner wall of the cylinder body to separate the space between the outer wall of the rod-shaped lost object and the inner wall of the cylinder body. However, this tool is different from the present application and does not have the function of establishing circulation.

[0005] The Chinese patent with the application number "CN201320747715.4" and the name "A partial reverse circulation fishing tool" discloses a partial reverse circulation fishing tool. An outer cylinder is connected to the outer wall of the upper sub of the fishing tool. The lower end of the upper sub is connected to an inner cylinder. The lower end of the outer cylinder is connected to the outer wall of the inner cylinder. A water baffle is connected to the inner wall at the lower end of the upper sub. A water eye communicating with the annulus between the outer cylinder and the inner cylinder is opened on the side wall of the upper sub at the upper end of the water baffle. The inner water outlet sleeve is connected to the side walls of the outer cylinder and the inner cylinder to communicate the inside of the inner cylinder with the outside of the outer cylinder. A precipitation assembly that can be opened by the pressure from bottom to top is installed at the lower end inside the inner cylinder. A water eye is opened on the side wall at the lower end of the outer cylinder. The patented device has the advantages of changing the circulation direction, fishing small lost objects, and milling and preventing jamming, and overcomes the deficiencies of the difficult fishing of small lost objects in existing lost circulation wells and milling and sticking of drill pipes. However, the structure of the patented device is relatively complex compared with the existing ones. During fishing, the baffle needs to be closed, and the flow direction of the drilling fluid only changes inside the tool, while the present application can work properly without closing the water eye channel.

[0006] The Chinese patent with the application number "CN201520453585.2" and the name "Bypass pressure relief sub" discloses a bypass pressure relief sub. The sub includes a sub body. A through sub inner hole is provided in the sub body. A bypass side hole communicating with the sub inner hole is radially provided on the sub body. A sealing diaphragm pad that can block the internal channel of the bypass side hole is fixedly installed in the bypass side hole. The bypass side hole is a stepped hole with a wide outer part and a narrow inner part. A thread is provided in the wide hole section of the bypass side hole. A threaded set screw is fixedly installed in the wide hole section of the bypass hole through the thread. The sealing diaphragm pad is pressed and fixed on the stepped end face inside the bypass hole by the threaded set screw. A through hole is provided in the middle of the threaded set screw. When the bit water eye is blocked, the patented sub can establish a drilling fluid circulation channel by pressing the sealing diaphragm pad to break it and opening the bypass side hole by applying pressure to the well. However, the patented sub is used by dropping a ball after relieving the pressure of the downhole drill string when the circulation cannot be established in the well. It is added above the back pressure valve in the drill string. Once opened, the blowout prevention inside the drill string fails, and the well control risk increases. While the present application does not require dropping a ball during use and is applicable to any size of fishing drill string combination. Summary of the Invention

[0007] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies existing in the prior art. For example, one of the purposes of the present invention is to solve the problem that when dealing with downhole faults and fishing routinely, the pump needs to be stopped, and the formation of the uncemented open hole section above the fish is prone to collapse and stick the drill string; the second purpose is to solve the problem that when the water eye of the fish is blocked, it is impossible to circulate in time, and the oil and gas accumulated at the bottom of the well are prone to cause well control risks.

[0008] To achieve the above object, on the one hand, the present invention provides a downhole fault treatment device, which may include an outer combined tool string and an inner combined tool string. Among them, the outer combined tool string includes a milling head, a milling pipe, a double-stage coupling joint, and a safety joint arranged in sequence from bottom to top; the inner combined tool string includes a fishing tool, a back pressure valve, and a circulation joint arranged in sequence from bottom to top; the inner combined tool string is located in the milling pipe, and the circulation joint is connected to the double-stage coupling joint; the circulation joint includes a body, a main water eye, and a side water eye. The main water eye is arranged along the central axis direction of the body, and the side water eye is opened on the side wall of the body and communicates with the main water eye.

[0009] According to an exemplary embodiment of one aspect of the present invention, the side water eye may be arranged in an obliquely downward direction and may form an angle of 0 to 90° with the main water eye; the radial diameter of the side water eye may be smaller than the radial diameter of the main water eye.

[0010] According to an exemplary embodiment of one aspect of the present invention, a male thread may be provided at the lower end of the body, and a female thread may be provided at the upper end of the body; the fishing tool may be a male taper or a female taper.

[0011] On the other hand, the present invention provides a downhole fault treatment method, which can be implemented by the above-mentioned downhole fault treatment device, and the method may include the steps of: lowering the downhole fault treatment device to a position 0.5 to 1.0 m above the fish top of the fish, and flushing the fish top; testing the torque and hook load during lifting, lowering, and static states under two states of pumping and stopping the pump; starting the pump and slowly lowering the device to probe the fish head; lifting the device, and adjusting the operation parameters according to the results of the above tests, with the rotational speed being 30 to 50 RPM and the drilling pressure being 10 to 30 KN; lowering the device to carry out milling and fishing.

[0012] On yet another aspect, the present invention provides a downhole fault treatment device, which may include a fishing tool, a safety joint, a back pressure valve, and a circulation joint arranged in sequence from bottom to top. Among them, the circulation joint includes a body, a main water eye, and a side water eye. The main water eye is arranged along the central axis direction of the body, and the side water eye is opened on the side wall of the body and communicates with the main water eye.

[0013] According to an exemplary embodiment of yet another aspect of the present invention, the side water eye may be arranged in an obliquely downward direction and may form an angle of 0 to 90° with the main water eye; the radial diameter of the side water eye may be smaller than the radial diameter of the main water eye.

[0014] According to an exemplary embodiment of yet another aspect of the present invention, a male thread may be provided at the lower end of the body, and a female thread may be provided at the upper end of the body; the fishing tool may be a male taper or a female taper.

[0015] Another aspect of the present invention provides a downhole fault treatment method, which can be implemented by the downhole fault treatment device as described above, and the method may include the steps of: lowering the downhole fault treatment device to a position 0.5 - 1.0 m above the fish top of the fish, and flushing the fish top; testing the torque and hook load during hoisting, lowering and static states in both the pump-on and pump-off conditions; turning on the pump, and slowly lowering the device to probe the fish head; hoisting the device, and adjusting the operation parameters according to the test results, with the drilling speed being 10 RPM and the drilling pressure being 10 - 30 KN; lowering the device to perform milling and fishing.

[0016] Another aspect of the present invention provides a circulating sub, characterized in that the circulating sub may include a body, a main water eye and a side water eye, wherein the main water eye is arranged along the central axis direction of the body, and the side water eye is opened on the side wall of the body and communicated with the main water eye.

[0017] According to an exemplary embodiment of another aspect of the present invention, the side water eye may be arranged obliquely downward and form an angle of 0 - 90° with the main water eye; the radial diameter of the side water eye may be smaller than the radial diameter of the main water eye.

[0018] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0019] (1) The circulating sub proposed by the present invention is beneficial for handling downhole faults, can work normally without closing the water eye channel, and does not require ball dropping during use. It is an auxiliary tool during fishing. In previous conventional fishing operations, the pump had to be stopped for fishing. After adding the circulating sub, it is not necessary to stop the pump for fishing.

[0020] (2) The downhole fault treatment device proposed by the present invention is designed to maintain circulation throughout the fishing process, aiming to keep the entire fishing process circulating smoothly, which can avoid the well control risk during the treatment of oil and gas layers and the risk of collapse and sticking caused by the easily collapsible formation in the upper open hole section, and avoid the waste of drilling fluid and environmental protection risk caused by the blocked fish eye during tripping out.

[0021] (3) The downhole fault treatment method proposed by the present invention has the functions of increasing the tripping out speed, reducing economic losses and negative impacts. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Through the following description with reference to the drawings, the above and other objects and features of the present invention will become more clear, wherein:

[0023] Figure 1 shows a schematic structural diagram of the circulating sub according to Exemplary Embodiment 1 of the present invention;

[0024] Figure 2 shows a parameter curve graph of the drill floor, drilling, mud pump, time and pit volume during fishing when applying the circulating sub of the present invention;

[0025] Figure 3 For Figure 2 gray-scale image;

[0026] Figure 4 shows a schematic structural diagram of the downhole fault handling device according to Exemplary Embodiment 2 of the present invention;

[0027] Figure 5 shows a schematic structural diagram of the downhole fault handling device according to Exemplary Embodiment 4 of the present invention.

[0028] Reference numerals:

[0029] 1 - milling head, 2 - milling pipe, 3 - double - stage coupling, 4 - safety joint, 5 - fishing tool, 6 - back - pressure valve, 7 - circulation joint, 71 - body, 72 - main water eye, 73 - side water eye, 74 - male thread, 75 - female thread, 8 - double - male short joint. Detailed implementation manners

[0030] Hereinafter, a circulation joint, a downhole fault handling device and a method of the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0031] In the description of the present application, it should be understood that the orientation or positional relationships indicated by the terms "inside", "above", "below", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present application.

[0032] The terms "first", "second", "third", "fourth", "fifth", etc. are only for convenience of description and easy distinction, and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined with "first", "second", "third", "fourth", "fifth", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0033] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] Exemplary Embodiment 1

[0035] This exemplary embodiment provides a circulating sub.

[0036] Figure 1 The structural schematic diagram of the circulating sub of Exemplary Embodiment 1 of the present invention is shown; Figure 2 The parameter curve graph of the drill floor, drilling, mud pump, time, and pit volume when the circulating sub of the present invention is applied during fishing is shown; Figure 3 is Figure 2 the grayscale image of. The following will describe the circulating sub of this exemplary embodiment in conjunction with Figures 1 to 3 It should be noted that the direction from top to bottom described in the specification is the direction from left to right in Figure 1 .

[0037] As Figure 1 shown, the circulating sub mainly includes a body 71, a main water eye 72, and a side water eye 73. Among them, the main water eye 72 is arranged along the central axis direction of the body 71, and the side water eye 73 is opened on the side wall of the body 71 and communicates with the main water eye 72. The body refers to the main part of the sub. After entering the well, under the action of the pump pressure, the drilling fluid flows from top to bottom inside (the flow direction is from the female end to the male end). The main water eye penetrates through the main part of the sub and is the flow channel of the drilling fluid. It flows out through the tool water eye under this sub and enters the annulus between the wellbore and the downhole drill string, returns to the surface, and then is pumped into the drill string water eye by the drilling pump, thus forming the circulating process of the drilling fluid. The side water eye communicates with the main water eye on the sub body. Under the action of the pump pressure, the drilling fluid flows from top to bottom, flowing both downward through the main water eye and out through the side water eye. When the fishing tool under this sub catches the fish and the fish water eye is blocked, the part below the side water eye of this sub cannot form a circulation channel, and all the drilling fluid flows out through the side water eye to form a circulation channel; when the fishing tool under the sub catches the fish and the fish water eye is unblocked, the circulating sub can form a circulation channel, and the drilling fluid flows out through the main water eye of the tool or fish under the sub and the side water eye of the sub to jointly form a circulation channel.

[0038] In this exemplary embodiment, the side water eye is the water eye opened on the body of the circulating sub, and the main water eye is the water eye passing through the central axis of the circulating sub. The two water eyes form a certain included angle, which is mainly convenient for when the fish-trap water eye at the lower part of the main water eye is blocked, the drilling fluid can establish an effective circulation through the side water eye without taking any measures, ensuring downhole safety and avoiding the inability to establish a circulation when the fish-trap water eye being fished is blocked, thereby increasing the risk. The side water eye can be arranged in a downward-slanting direction, which is beneficial to bringing sundries and the like at the lower part to the ground through the circulation. The included angle between the side water eye and the main water eye can be 0 to 90°, such as 30°, 45°, 50° or 60°. To ensure that the drilling fluid coming out of the side water eye has little erosive damage to the wellbore wall of the open hole section and is not likely to cause the collapse of the wellbore wall in the unstable well section, thereby avoiding the fish at the lower part of the sub being buried and avoiding increasing the operation risk, preferably, a side water eye with an included angle of 30° with the main water eye is adopted.

[0039] Furthermore, the side water eyes can be evenly arranged around the main water eye. Multiple sets of side water eyes can be arranged on the body.

[0040] Still further, the radial diameter of the side water eye can be smaller than the radial diameter of the main water eye. There are at least two considerations for such a setting. One is that when the drilling fluid reaches the main water eye above the side water eye from the upper drill string and other tools, with the pressure generated by the surface drilling pump remaining unchanged, when the fish-trap water eye of the sub is blocked, the pressure generated by the drilling fluid passing through the side water eye will be greater, which is more conducive to cleaning sundries in the well. The other is that if the diameter of the side water eye is too large, the strength of the sub body will be reduced, increasing potential safety hazards.

[0041] In this exemplary embodiment, as Figure 1 shown in, a male thread 74 can be provided at the lower end of the body 71, and a female thread 75 can be provided at the upper end of the body 71. This circulating sub can be connected to the downhole drill string or other drill string combination tools through standard drill string thread connections.

[0042] In this exemplary embodiment, the specific process of constructing the circulation of the circulating sub of the present invention is as follows: When the fish-trap water eye is unblocked, the drilling fluid flows through the upper drill string to the main water eye of the circulating sub, and then flows to the lower tool and the fish. During this process, the drilling fluid also flows out of the circulating sub from the side water eye and flows upward together with the drilling fluid flowing out of the lower tool and the fish for circulation. When the fish-trap water eye is blocked, the drilling fluid flows through the upper drill string to the main water eye of the circulating sub, and then flows to the lower tool and the fish. The drilling fluid does not flow out of the lower tool and the fish. During this process, the drilling fluid flows out of the circulating sub from the side water eye and flows upward for circulation.

[0043] Use the downhole fault treatment device or downhole drilling tool with the circulating sub of the present invention to fish for the fallen fish. It is used in multiple wells such as the first well, the second well, the third well, the fourth well, the fifth well, etc. During the entire fishing process, fishing can be carried out without stopping the pump, and the downhole always maintains a circulating state, effectively avoiding well control risks and the risk of collapse and sticking of the upper easily caving open-hole section, and successfully completing the fishing operation. In the case where the water eye of the fallen fish is blocked, it can effectively avoid the ejection of drilling fluid during tripping, avoid waste of drilling fluid, reduce environmental protection pressure, increase the tripping speed, and achieve the expected effect.

[0044] In fact, the circulating sub of the present invention can be used both in the process of dealing with downhole faults during drilling operations and in the fishing process of workover operations. The circulating sub of the present invention has been successfully used in multiple wells and can be promoted in the industry.

[0045] Figure 2 The curve graphs of the drill floor, drilling, mud pump, time, and pit volume parameters during fishing when applying the circulating sub of the present invention are shown. Figure 3 is Figure 2 gray scale image of. Figure 2Among them, in the figure of the column belonging to "drilling floor parameters", the blue curve is the "hook height" curve, that is, the curve of lifting the drill string after the fishing operation is completed. In the figure of the column belonging to "drilling parameters", the red curve is the "standpipe pressure" curve, that is, the pressure curve during the fishing process; the magenta curve is the "torque" curve for back-off fishing, that is, the torque curve during the fishing process. In the figure of the column belonging to "mud pump parameters", the red curve is the "use of pump No. 1" curve, and the blue-red curve is the "use of pump No. 2" curve, that is, the stroke curve of pump No. 2 during the fishing process. Before this fishing operation, two pumps were used to flush the fish head (fish top) at a large displacement. This fishing operation belongs to an integrated operation of overfishing (reaming and fishing). Before the reaming head of the integrated reaming reaches the fish head (fish top), two pumps are turned on to flush the fish head (fish top) at a large displacement, and then one pump is stopped for reaming and fishing. After the fishing operation is completed, the pump that was stopped during fishing is turned on again. Throughout the process, one pump is always working. In the figure of the column belonging to "volume tank parameters", the magenta curve is the "outlet displacement (flow rate)" curve, that is, the outlet flow rate curve during the fishing process. When both pump No. 1 and pump No. 2 in the figure of the column belonging to "mud pump parameters" are used, the "standpipe pressure" curve in the figure of the column belonging to "drilling parameters" will be higher. When only pump No. 2 in the figure of the column belonging to "mud pump parameters" is used, the "standpipe pressure" curve in the figure of the column belonging to "drilling parameters" will be lower. The "torque" curve for back-off fishing in the figure of the column belonging to "drilling parameters" changes continuously during back-off. Pump No. 2 in the figure of the column belonging to "drilling pump parameters" is always in use, and the "standpipe pressure" curve in the figure of the column belonging to "drilling parameters" always exists. After the back-off fishing is completed, pump No. 1 in the figure of the column belonging to "mud pump parameters" is also used. At this time, both mud pumps are in use, and the red curve in the figure of the column belonging to "drilling parameters" for the "standpipe pressure" curve rises, and the "hook height" curve in the figure of the column belonging to "drilling floor parameters" rises (when lifting the drill string). Throughout the back-off fishing process, the magenta curve in the figure of the column belonging to "tank volume parameters" for the "outlet displacement (flow rate)" curve always exists, indicating that the mud pump has been in use. It can be seen that by using the circulating sub of the present invention, fishing can be achieved without stopping the pump throughout the process, while conventional fishing requires stopping the pump. The present invention can realize the transformation from fishing with pump stop to fishing without pump stop, changing the fishing process.

[0046] Exemplary Embodiment 2

[0047] This exemplary embodiment provides a downhole fault treatment device.

[0048] Figure 4 The structural schematic diagram of the downhole fault treatment device of Exemplary Embodiment 2 of the present invention is shown. The following combines Figure 4 to describe the downhole fault treatment device of this exemplary embodiment. It should be noted that the direction from top to bottom described in the specification is the same as Figure 4 the direction from right to left in

[0049] The downhole fault treatment device of the present invention can be used in well drilling operations to handle downhole faults and can also be used in the fishing process during workover operations.

[0050] The downhole fault treatment device of this exemplary embodiment may include an outer combined tool string and an inner combined tool string.

[0051] As Figure 4 shown in the figure, the outer combined tool string includes a milling head 1, a milling pipe 2, a double-stage coupling joint 3, and a safety joint 4 arranged in sequence from bottom to top. The milling pipe 2 can be connected to the milling head 1 through a double-male short joint 8. The length of the milling pipe can be increased according to the specific downhole situation. The increasing method is as follows: One milling pipe and one double-male short joint form a group. The connection between the milling pipes and between the milling pipe and the milling head can be achieved by adding double-male short joints. The connection buckle of the milling pipe in this application is designed as a double-female buckle. Adding double-male short joints increases the strength, reduces the risk of the milling pipe breaking and falling into the well, and increases the safety of the tool combination. The inner combined tool string includes a fishing tool 5, a back-pressure valve 6, and a circulation joint 7 arranged in sequence from bottom to top. The inner combined tool string is located in the milling pipe 2, and the circulation joint 7 is connected to the double-stage coupling joint 3. The circulation joint may include the circulation joint described in the above exemplary embodiment 1.

[0052] In this exemplary embodiment, the fishing tool can be a male tap or a female tap.

[0053] In this exemplary embodiment, the upper end of the safety joint can be connected to a drill string combination tool. The drill string combination tool may include a first drill collar, a downhole shock absorber, a second drill collar, and a drill pipe arranged in sequence from bottom to top.

[0054] Exemplary Embodiment 3

[0055] This exemplary embodiment provides a downhole fault treatment method.

[0056] The downhole fault treatment method can be implemented by the downhole fault treatment device described in the above exemplary embodiment 2. When the milling head is severely worn during the milling process and the fishing fish top has not been milled to, after pulling out the drill string to replace the milling head and then lowering this device.

[0057] The downhole fault treatment method may include the following steps:

[0058] S1. Lower the last stand of drill pipe and connect the top drive or the kelly bar. Set the maximum torque value of the top drive (the rotary table is not set). Mark the fish top depth. Slowly start the top drive or the rotary table to break the static shear force of the drilling fluid. Here, the top drive or the rotary table are two types of equipment of the driving device, and their functions are to provide power and torque.

[0059] S2. Slowly start the mud pump. After the drilling fluid returns from the outlet, increase the displacement to the milling displacement and lower to 0.50 - 1.0 m above the top. Flush the fish top with a large displacement for 5 - 10 minutes.

[0060] S3. Test the torque and hook load during the processes of lifting, lowering, and remaining stationary in both the pump-starting and pump-stopping states.

[0061] S4. Start the pump and slowly lower the device to probe the fish head.

[0062] S5. Lift the device and adjust the parameters according to the results of the above tests. The weight on bit is 10 - 30 KN, the rotary speed is 30 - 50 RPM, and the displacement is determined according to the wellbore size. Here, the weight on bit of 10 - 30 KN is the range of the weight on bit variation involved in the entire operation process. During over milling, the pressure applied to the fish head is the weight on bit of 10 - 20 KN in the over milling parameters. This parameter is a range, not a fixed value. For the integrated over milling and fishing tool just entering the well, due to the sharp milling teeth, the applied weight on bit is relatively small. After over milling for some time, the milling teeth are worn, and the applied weight on bit is higher. During threading, the weight on bit is 10 - 30 KN, and its upper limit is higher than that during over milling. The rotary speed of 30 - 50 RPM is the rotary speed at which the downhole fishing device and related tools are driven to rotate by the rotation of the top drive or rotary table during over milling. It is a range, not a fixed value. For the integrated over milling and fishing tool just entering the well, due to the sharp milling teeth, the rotary speed is relatively high. After over milling for some time, the milling teeth are worn, and the rotary speed is lower. Therefore, the rotary speed is a range value. The displacement is determined according to the wellbore size. For example, when conducting fishing or integrated over milling and fishing operations, the wellbore with a size of 114 mm is smaller than that with a size of 215.9 mm. Correspondingly, the annulus (the annular space between the drill string or the body of the downhole tool and the inner wall of the wellbore) of the former is also smaller than that of the latter. The displacement of the drilling pump during fishing or integrated over milling and fishing is much smaller. Therefore, the displacement needs to be determined according to the wellbore size.

[0063] S6. When the over milling tool inside the milling pipe enters the fish top, the pump pressure rises and the torque increases. The weight on bit is 10 - 30 KN. When the corresponding torque value on the torque meter of the top drive or rotary table reaches the set torque and jams, slowly reverse the top drive or rotary table to release the torque.

[0064] S7. Slowly start the top drive or rotary table. If the torque still jams the corresponding torque value on the torque meter of the top drive or rotary table, slowly release the torque and continue to repeat the operation until the torque reaches a peak and then slowly decreases, indicating successful threading, back threading, and fishing. If the water eye of the fish is unblocked, the pump pressure drops; if the water eye of the fish is blocked, the pump pressure remains unchanged.

[0065] S8. Lift the device and carefully observe whether the hook load indicated on the weight indicator increases. If the increase in hook load is obvious, more fish are caught during threading, back threading, and fishing; if the increase in hook load is not obvious, fewer fish are caught during threading, back threading, and fishing.

[0066] S9. Lift the device sharply by 5 - 6 m and then brake suddenly, lower the device sharply by 3 - 4 m and then brake suddenly. Operate the device in this way for 3 - 5 times. If the hook load does not decrease, the threading, back threading, and fishing of the fish are successful.

[0067] S10. Circulate the drilling fluid for more than 1.5 circulation periods. If it complies with the well control regulations, the drill string can be pulled out of the hole.

[0068] Exemplary Embodiment 4

[0069] This exemplary embodiment provides a downhole fault treatment device.

[0070] Figure 5 The structural schematic diagram of the downhole fault treatment device according to Exemplary Embodiment 4 of the present invention is shown. The following will describe the downhole fault treatment device of this exemplary embodiment in conjunction with Figure 5 It should be noted that the direction from top to bottom described in the specification is the direction from right to left in Figure 5 the figure.

[0071] The downhole fault treatment device of the present invention can be used to handle downhole faults during drilling operations and can be used in the fishing process of workover operations.

[0072] As Figure 5 shown in the figure, the downhole fault treatment device of this exemplary embodiment may include a fishing tool 5, a safety sub 4, a back pressure valve 6, and a circulation sub 7 arranged in sequence from bottom to top. The circulation sub may include the circulation sub described in the above Exemplary Embodiment 1.

[0073] In this exemplary embodiment, the fishing tool may be a male tap or a female tap.

[0074] In this exemplary embodiment, the upper end of the circulation sub may be connected to a drill string assembly tool, and the drill string assembly tool may include a first drill collar, a downhole shock absorber, a second drill collar, and a drill pipe arranged in sequence from bottom to top.

[0075] When using the device with a circulation sub of the present invention, such as the downhole fault treatment device of Exemplary Embodiment 2 or Exemplary Embodiment 4, for fishing a fish that has fallen into the well, if the water eye of the fallen fish is unblocked, the entire fishing process is circulated through the water eye of the fallen fish and the side water eye of the circulation sub body; if the water eye of the fallen fish is blocked, the entire fishing process is circulated through the side water eye of the circulation sub body. Whether there is oil and gas accumulated downhole after fishing the fallen fish or not, since a circulation is established throughout the process, the well control risk can be effectively avoided. The collapse debris in the upper easily caving open hole section during fishing can be circulated out of the ground through the established circulation, effectively avoiding sticking due to collapse. That is, whether the water eye of the fallen fish is unblocked during the process of pulling out the drill string, the drilling fluid in the drill string water eye can flow out through the side water eye of the downhole fault treatment circulation sub body, and the phenomenon of column spraying of drilling fluid will not occur due to the blockage of the water eye of the fallen fish.

[0076] Exemplary Embodiment 5

[0077] This exemplary embodiment provides a downhole fault treatment method.

[0078] The downhole fault handling method can be implemented by the downhole fault handling device described in the above exemplary embodiment 4.

[0079] The downhole fault handling method may include the following steps:

[0080] S1. Lower the last stand of drill pipe and connect the top drive or kelly. Set the maximum torque value of the top drive (do not set for the rotary table), mark the fish top square entry, and slowly start the top drive or rotary table to break the static shear force of the drilling fluid.

[0081] S2. Slowly start the mud pump. After the drilling fluid returns at the outlet, increase the displacement to the milling displacement and lower it to 0.50 - 1.0 m above the top. Flush the fish top with a large displacement for 5 - 10 minutes.

[0082] S3. Measure the torque and hook load during hoisting, lowering, and static states under both the pump - on and pump - off conditions.

[0083] S4. Turn on the pump, set the top drive or rotary table to 10 RPM, and slowly lower the device to probe the fish head.

[0084] S5. Apply a pressure of 10 - 30 KN to make a connection. Wait until the top drive stalls or the corresponding torque value appears on the rotary table torque meter. Slowly release the torque of the top drive or rotary table to let the top drive or rotary table reverse, and replenish the weight on bit in a timely manner when the weight on bit decreases.

[0085] S6. Repeat step S5 one to two times to ensure 3 - 5 effective connection turns.

[0086] S7. Hoist the device and carefully observe the change in the hook load on the weight indicator. If the hook load increases significantly, there are more fish caught by making and breaking connections; if the hook load increase is not obvious, there are fewer fish caught by making and breaking connections.

[0087] S8. Hoist the device sharply by 5 - 6 m and then brake sharply, lower the device sharply by 3 - 4 m and then brake sharply. Operate the device in this way three to five times. If the hook load does not decrease, the fish has been successfully caught by making and breaking connections.

[0088] S9. Circulate the drilling fluid for more than 1.5 circulation cycles. If it meets the well control requirements, then pull out the drill string.

[0089] In summary, the advantages proposed by the present invention include at least one of the following:

[0090] (1) The circulation sub proposed by the present invention is a preventive tool that can be used multiple times, has the characteristics of low cost, and has strong promotion value.

[0091] (2) The circulation sub proposed by the present invention is used to fish the drill string assembly and is applicable to any size of the fishing drill string assembly. The circulation sub is added above the back pressure valve to change the fishing process, which can effectively avoid major risks such as well control and pipe sticking.

[0092] (3) The downhole fault treatment device proposed by the present invention can effectively avoid well control risks during fishing for the dropped fish, and avoid the economic losses and negative impacts caused by the abandonment of the wellbore due to the burial of tools, having great economic value and social benefits.

[0093] (4) The downhole fault treatment method proposed by the present invention can reduce the waste of drilling fluid, reduce the environmental protection pressure, and at the same time improve the tripping speed.

[0094] Although a circulation sub, a downhole fault treatment device and method of the present invention have been described above by combining exemplary embodiments, those skilled in the art should understand that various modifications and changes can be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined by the claims.

Claims

1. An underground fault handling device, characterized in that, The device includes an outer combined tool string and an inner combined tool string, wherein, The outer combined tool string includes a milling head, a milling pipe, a double-stage coupling joint and a safety joint arranged successively from bottom to top; the inner combined tool string includes a fishing tool, a back pressure valve and a circulation joint arranged successively from bottom to top; the inner combined tool string is located in the milling pipe, and the circulation joint is connected to the double-stage coupling joint; the circulation joint includes a body, a main water eye and a side water eye, the main water eye is arranged along the central axis direction of the body, and the side water eye is opened on the side wall of the body and communicated with the main water eye.

2. The downhole fault handling device according to claim 1, characterized in that, The side water eye is arranged obliquely downward and forms an angle of 0-90° with the main water eye; the radial diameter of the side water eye is smaller than the radial diameter of the main water eye.

3. The downhole fault handling device according to claim 1, characterized in that, A male thread is arranged at the lower end of the body, and a female thread is arranged at the upper end of the body; the fishing tool is a male taper or a female taper.

4. A downhole fault handling method, characterized in that, The method is realized by the downhole fault treatment device according to any one of claims 1 to 3, and the method includes the steps of: Lower the downhole fault treatment device to a position 0.5-1.0 m above the fish top of the fallen fish, and flush the fish top. Test the torque and hook load during hoisting, lowering and static states under two conditions of pumping and stopping pumping. Pump, and slowly lower the device to probe the fish head. Hoist the device, and adjust the operation parameters according to the results of the above tests, the rotation speed is 30-50 RPM, and the drilling pressure is 10-30 KN. Lower the device to perform milling fishing.

5. An underground fault handling device, characterized in that, The device includes a fishing tool, a safety joint, a back pressure valve and a circulation joint arranged successively from bottom to top, wherein, The circulation joint includes a body, a main water eye and a side water eye, the main water eye is arranged along the central axis direction of the body, and the side water eye is opened on the side wall of the body and communicated with the main water eye.

6. The downhole fault treatment device according to claim 5, characterized in that, The side water eye is arranged obliquely downward and forms an angle of 0-90° with the main water eye; the radial diameter of the side water eye is smaller than the radial diameter of the main water eye.

7. The downhole fault treatment device according to claim 5, wherein A male thread is arranged at the lower end of the body, and a female thread is arranged at the upper end of the body; the fishing tool is a male taper or a female taper.

8. A downhole fault handling method, characterized in that, The method is realized by the downhole fault treatment device according to any one of claims 5 to 7, and the method includes the steps of: Lower the downhole fault treatment device to a position 0.5-1.0 m above the fish top of the fallen fish, and flush the fish top. Test the torque and hook load during hoisting, lowering and static states under two conditions of pumping and stopping pumping. Pump, and slowly lower the device to probe the fish head. Hoist the device, and adjust the operation parameters according to the results of the above tests, the drilling speed is 10 RPM, and the drilling pressure is 10-30 KN. Lower the device to perform milling fishing.

9. A circulating joint, characterized in that, The circulation joint includes a body, a main water eye and a side water eye, wherein, the main water eye is arranged along the central axis direction of the body, and the side water eye is opened on the side wall of the body and communicated with the main water eye.

10. The circulation joint according to claim 9, wherein, The side water eye is arranged obliquely downward and forms an angle of 0-90° with the main water eye; the radial diameter of the side water eye is smaller than the radial diameter of the main water eye.

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