Coiled tubing downhole localized backflushing well cleaner

Abstract

The utility model relates to a coiled tubing downhole local reverse circulation well cleaning device, belong to oil and gas well drilling, work over and well logging technical field, including cylinder, the positive circulation passage is formed in the cylinder, the switch valve for the through or cut off positive circulation passage is equipped in the cylinder, the cylinder is equipped with from the reverse circulation passage that cylinder outer communication to switch valve below of cylinder inside of switch valve top, the cylinder still is equipped with the liquid return passage that cylinder inside and outside are connected and are located switch valve below, the cylinder still is equipped with the fishing device that is located liquid return passage below in the cylinder. The utility model not only realized downhole positive circulation large displacement well washing, and can large displacement, high pump pressure reverse circulation fishing, can realize the quick cleaning of well bottom in one trip pipe column, also has the function of fishing of big and small falling objects simultaneously, ensures the thorough cleaning of well bottom.

Description

Technical Field

[0001] This utility model relates to a coiled tubing downhole partial reverse circulation well cleaning device, belonging to the field of oil and gas well drilling, workover and logging technology. Background Technology

[0002] In complex drilling, workover, and logging operations in oil and gas wells, stuck pipe accidents are frequently encountered, and these accidents often cannot be resolved after retrieval. In such cases, milling operations are necessary to clean the area around the stuck pipe and casing, and then retrieve it. Alternatively, after successful retrieval of the pipe string, a thorough cleaning of the well bottom is required to ensure cleanliness and prevent secondary accidents. If forward circulation or retrieval techniques are used, difficulties arise in carrying or retrieving the stuck pipe, especially since forward circulation techniques cannot meet the requirements of milling operations in complex conditions of deep and horizontal wells.

[0003] To avoid stuck drill pipe accidents and improve carrying or retrieval efficiency, high pump pressure, large displacement, and overall reverse circulation carrying or retrieval processes are currently widely used. However, this method has a long construction cycle, high construction costs, and risks of tubing blockage or wellbore collapse. Therefore, in practice, partial reverse circulation tools are mostly used. However, in actual use, there are still problems such as the retrieval claws being too dense and too short, which cannot meet the needs of retrieving large objects, resulting in low retrieval efficiency and high costs.

[0004] For example, patent CN120100342A discloses a horizontal well reverse circulation continuous sand flushing method. Utilizing a reversing short connector, during the sand flushing operation, the lateral channel of the reversing short connector is closed, while the bridge-type channel is open. The sand flushing fluid enters the well from the annulus, flows through the tubing via the bridge-type channel of the reversing short connector, and exits the well from the tap. During the single-joint replacement process, the lateral channel of the reversing short connector is opened, and the sand flushing fluid enters the well from the annulus, flows through the tubing via the side opening of the reversing short connector, and exits the well from the side opening of the wellhead sealing device. However, this method is inconvenient to use, has low retrieval efficiency, and cannot handle situations with a large amount of downhole debris. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a continuous tubing downhole local reverse circulation well cleaning device, which can quickly clean the bottom of the well through forward and reverse circulation, and simultaneously retrieve downhole debris.

[0006] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A coiled tubing downhole partial reverse circulation cleaning device includes a cylinder, a positive circulation channel is formed inside the cylinder, a switch valve for opening or cutting off the positive circulation channel is provided inside the cylinder, a reverse circulation channel is provided inside the cylinder above the switch valve and outside the cylinder below the switch valve, a return fluid channel is also provided inside the cylinder and located below the switch valve, and a retrieval device is also provided inside the cylinder below the return fluid channel.

[0007] The beneficial effects of this utility model are: This utility model not only realizes downhole positive circulation large-volume well washing, but also can achieve large-volume, high-pump-pressure reverse circulation retrieval, which can realize the rapid cleaning of the bottom of the well with one trip of tubing string, and has the function of retrieving objects of different sizes at the same time, ensuring the thorough cleaning of the bottom of the well.

[0008] Based on the above technical solution, the present invention can be further improved as follows.

[0009] Furthermore, the cylinder body includes an inner cylinder and an outer cylinder. The inner cylinder is connected to the middle part of the outer cylinder. The positive circulation channel is formed in the upper end of the outer cylinder, the inner cylinder, and the lower end of the outer cylinder. The switch valve is disposed in the upper end of the inner cylinder. The upper end face of the inner cylinder is provided with an inner cylinder outer circulation hole extending downward to the middle or lower part of the inner cylinder. The outer cylinder is provided with an outer cylinder outlet communicating with the inner cylinder outer circulation hole. The inner cylinder outer circulation hole and the outer cylinder outlet form the reverse circulation channel. The upper part of the inner cylinder is provided with an inner cylinder return port. The outer cylinder is provided with an outer cylinder return port communicating with the inner cylinder return port. The inner cylinder return port and the outer cylinder return port form the return channel.

[0010] The beneficial effect of adopting the above-mentioned further scheme is that the inner and outer cylinders form a double-layer structure. The positive circulation channel is set inside the inner cylinder, and the reverse circulation channel is set between the inner and outer cylinders and extends from top to bottom. The return fluid channel runs through the inner and outer cylinders. Through such a reasonable arrangement of the structure, various channels are formed to jointly achieve positive and reverse circulation well washing. The structural design is ingenious.

[0011] Furthermore, a step is provided in the middle or lower part of the outer cylinder, and the lower end of the inner cylinder abuts against the step.

[0012] The advantage of adopting the above-mentioned further solution is that the inner cylinder is positioned inside the outer cylinder by the step, which can prevent installation misalignment.

[0013] Furthermore, the inner cylinder and the outer cylinder are connected by connecting screws.

[0014] The beneficial effect of adopting the above-mentioned further solution is that the inner cylinder and the outer cylinder are locked together by connecting screws, which prevents the inner cylinder from moving inside the outer cylinder during well cleaning and ensures that each channel is connected according to the structural design.

[0015] Furthermore, the outer cylinder is provided with a plurality of outer cylinder connection positioning holes along its circumference, the inner cylinder is provided with a plurality of inner cylinder connection positioning holes along its circumference, and a plurality of connecting screws are provided, which are respectively connected to the corresponding outer cylinder connection positioning holes and the inner cylinder connection positioning holes.

[0016] The beneficial effect of adopting the above-mentioned further solution is that multiple circumferentially distributed connecting screws can make the connection between the inner and outer cylinders more secure, prevent misalignment in any direction, and ensure the accuracy of the connection.

[0017] Furthermore, at least one inter-cylinder upper sealing ring is provided between the upper part of the inner cylinder and the outer cylinder, and the inter-cylinder upper sealing ring is located above the lower end of the outer circulation hole of the inner cylinder.

[0018] Furthermore, at least one lower sealing ring is provided between the lower part of the inner cylinder and the outer cylinder, and the lower sealing ring is located below the liquid outlet of the outer cylinder.

[0019] The beneficial effect of adopting the above-mentioned further solution is that, due to the existence of the reverse circulation channel, the drilling fluid needs to flow through the reverse circulation channel to the gap between the cylinder and the wellbore. Therefore, upper and lower sealing rings can be set between the inner cylinder and the outer cylinder respectively to seal the gap between the inner cylinder and the outer cylinder.

[0020] Furthermore, the inner cylinder outer circulation hole and the outer cylinder liquid outlet are each provided with multiple corresponding holes along the circumference of the inner cylinder and the outer cylinder.

[0021] The beneficial effect of adopting the above-mentioned further solution is that multiple corresponding inner cylinder outer circulation holes and outer cylinder liquid outlets form multiple reverse circulation channels, which are distributed circumferentially, allowing drilling fluid to enter the gap between the cylinder and the wellbore in a circumferential manner, avoiding the problem of uneven flushing caused by a single reverse circulation channel or multiple reverse circulation channels together.

[0022] Furthermore, the upper end of the outer cylinder is connected to an upper connector, and a portion of the positive circulation channel is formed within the upper connector.

[0023] The beneficial effect of adopting the above-mentioned further scheme is that the outer cylinder can be connected to the upper tubing string through the upper connector, which facilitates the extension of the coiled tubing downhole local reverse circulation cleaning tool to the bottom of the wellbore, and can also deliver drilling fluid.

[0024] Furthermore, a scooping tube is connected to the lower end of the outer cylinder, and a portion of the positive circulation channel is formed inside the scooping tube.

[0025] Furthermore, the retrieval device is installed inside the retrieval tube.

[0026] The advantage of adopting the above-mentioned further solution is that the length of the cylinder and the positive circulation channel are extended downwards by designing a special retrieval cylinder, which facilitates the installation of the retrieval device.

[0027] Furthermore, the switching valve includes a ball seat and a reversing ball. The ball seat is connected to the cylinder body and has a vertically penetrating liquid inlet channel inside. The reversing ball is used to open or close the liquid inlet channel.

[0028] The advantage of adopting the above-mentioned further solution is that the structure of the switching valve selects the ball seat and the reversing ball. The ball seat is directly installed in the cylinder. Without the reversing ball, the positive circulation channel is open. When the reversing ball is inserted, the positive circulation channel is cut off, which simplifies the operation.

[0029] Furthermore, the liquid inlet channel has an inverted frustum-shaped structure with a large diameter at the top and a small diameter at the bottom. The diameter of the reversing ball is smaller than the diameter at the top of the liquid inlet channel but larger than the diameter at the bottom of the liquid inlet channel.

[0030] The advantage of adopting the above-mentioned further solution is that the reversing ball is inserted and stuck at the lower end of the liquid inlet channel, thereby cutting off the positive circulation channel. The shape design of the ball seat can achieve the cutting off of the positive circulation channel in conjunction with the reversing ball. No additional structure is required. The structure is simple, easy to implement, and low in cost.

[0031] Furthermore, the reversing ball is a soluble ball that dissolves after a set time of contact with the fluid.

[0032] The advantage of adopting the above-mentioned further solution is that the design of the soluble reversing ball eliminates the need for additional downhole tool unsealing steps. The soluble ball automatically dissolves in the fluid within a set time, simplifying the operation process.

[0033] Furthermore, the lower end of the cylinder is configured with drilling and milling teeth.

[0034] The beneficial effect of adopting the above-mentioned further solution is that the drill and milling teeth are equivalent to the cutter at the bottom of the cylinder, which makes it easier to move the debris at the bottom of the well, so that it can enter the retrieval cylinder with the fluid, be retrieved by the retrieval device and brought out of the well.

[0035] Furthermore, the salvage device includes multiple elastic claws, one end of which is connected to the cylinder body, and the other end extends toward the cylinder body and tilts upward.

[0036] The beneficial effect of adopting the above-mentioned further solution is that the elastic claws are specifically elastic and inclined. Multiple elastic claws form a structure similar to a fishing net. During reverse circulation well washing, the debris at the bottom of the well is carried upward from the bottom of the cylinder by the drilling fluid. The elastic claws deform first to allow the debris to enter the cylinder above the elastic claws. After the cleaning is completed, the cylinder is carried upward out of the well. At this time, when the debris falls downward, it is blocked by the elastic claws and kept in the cylinder. Finally, it is carried out of the well along with the cylinder.

[0037] Furthermore, the multiple elastic claws are arranged in multiple layers, with each layer of elastic claws evenly spaced along the circumference of the cylinder.

[0038] The beneficial effect of adopting the above-mentioned further scheme is that setting up multiple layers of elastic claws enables multi-layer retrieval, avoids debris falling out, and ensures that all debris at the bottom of the well is retrieved.

[0039] Furthermore, each layer of the elastic grabbing claws is provided with at least three, and the elastic grabbing claws of adjacent layers are staggered at a set angle to form a spiral grabbing claw net structure.

[0040] The beneficial effect of adopting the above-mentioned further solution is that the spiral claw net structure not only makes the elastic claws evenly and densely distributed in the cylinder, but also allows multiple elastic claws to cooperate with each other in a spiral distribution. Even if debris falls between adjacent elastic claws in the upper layer, it will be caught by the elastic claws in the lower layer, thereby achieving a better retrieval effect. Attached Figure Description

[0041] Figure 1 This is a structural diagram of a coiled tubing downhole partial reverse circulation well cleaning device according to the present invention;

[0042] Figure 2 This is a bottom view of a coiled tubing downhole partial reverse circulation well cleaning device according to this utility model;

[0043] Figure 3 This is a structural diagram of the outer cylinder of a continuous tubing downhole partial reverse circulation well cleaning device according to this utility model;

[0044] Figure 4 This is a structural diagram of the inner cylinder of a continuous tubing downhole partial reverse circulation well cleaning device according to this utility model;

[0045] Figure 5 This is a top view of the inner cylinder of a continuous tubing downhole partial reverse circulation well cleaning device according to this utility model.

[0046] The attached diagram lists the components represented by each number as follows:

[0047] 1. Upper connector; 2. Reversing ball; 3. Ball seat; 4. Upper sealing ring between cylinders; 5. Connecting screw; 6. Outer cylinder; 7. Inner cylinder; 8. Lower sealing ring between cylinders; 9. Retrieving cylinder; 10. Elastic retrieval claw; 11. Outer cylinder return port; 12. Inner cylinder return port; 13. Inner cylinder external circulation hole; 14. Outer cylinder outlet; 15. Drilling and milling teeth; 16. Outer cylinder connection positioning hole; 17. Inner cylinder connection positioning hole. Detailed Implementation

[0048] The principles and features of this utility model are described below. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0049] Example 1

[0050] like Figure 1 As shown, this embodiment 1 relates to a coiled tubing downhole partial reverse circulation cleaning device, including a cylinder, a positive circulation channel formed inside the cylinder, a switch valve for opening or closing the positive circulation channel inside the cylinder, a reverse circulation channel connecting the inside of the cylinder above the switch valve to the outside of the cylinder below the switch valve, a return fluid channel connecting the inside and outside of the cylinder and located below the switch valve, and a retrieval device located below the return fluid channel inside the cylinder.

[0051] In this embodiment 1, the cylinder is inserted into the bottom of the well, the switch valve is opened to open the positive circulation channel, and drilling fluid is introduced into the positive circulation channel directly to the bottom of the well from top to bottom to perform positive circulation cleaning of the bottom of the well. After that, the switch valve is closed to cut off the positive circulation channel, and the drilling fluid flows through the reverse circulation channel to the gap between the cylinder and the wellbore, and then flows through the bottom of the well and enters the cylinder from bottom to top in reverse, and finally flows out through the return fluid channel to the gap between the cylinder and the wellbore. The debris at the bottom of the well is backwashed into the cylinder, retrieved by the retrieval device, confined in the cylinder, and finally carried out of the wellbore along with the cylinder.

[0052] This embodiment 1 not only realizes downhole positive circulation large-volume well washing, but also large-volume, high-pump-pressure reverse circulation retrieval. In particular, the lower end is designed with a retrieval device (formed by spirally distributed elastic retrieval claws 10), which can realize the rapid cleaning of the bottom of the well in one trip of the tubing string, and has the function of retrieving objects of different sizes at the same time, ensuring the thorough cleaning of the bottom of the well.

[0053] It should be noted that the large displacement described above refers to the localized reverse circulation operation in the wellbore in the prior art. This means that the inner diameter of the upper connector, barrel, and other components of the tool is not smaller than the inner diameter of the upper tubing string, thus eliminating pressure loss. This allows for maximum displacement and efficient well bottom cleaning based on the tubing string inner diameter, wellbore annulus, well depth, and the performance of surface equipment. This invention exhibits no pressure loss under normal operating conditions, which is a significant improvement compared to existing technologies.

[0054] Example 2

[0055] like Figure 1-5As shown, based on the above embodiment 1, the cylinder of this embodiment 2 includes an inner cylinder 7 and an outer cylinder 6. The inner cylinder 7 is connected to the middle part of the outer cylinder 6. The positive circulation channel is formed in the upper end of the outer cylinder 6, the inner cylinder 7, and the lower end of the outer cylinder 6. The switch valve is disposed in the upper end of the inner cylinder 7. The upper end face of the inner cylinder 7 is provided with an inner cylinder external circulation hole 13 extending downward to the middle or lower part of the inner cylinder. The outer cylinder 6 is provided with an outer cylinder outlet 14 communicating with the inner cylinder external circulation hole 13. The inner cylinder external circulation hole 13 and the outer cylinder outlet 14 form the reverse circulation channel. The upper part of the inner cylinder 7 is provided with an inner cylinder return port 12. The outer cylinder 6 is provided with an outer cylinder return port 11 communicating with the inner cylinder return port 12. The inner cylinder return port 12 and the outer cylinder return port 11 form the return channel.

[0056] In this embodiment 2, the inner cylinder 7 and the outer cylinder 6 form a double-layer structure. The positive circulation channel is set inside the inner cylinder 7, and the reverse circulation channel is set between the inner cylinder 7 and the outer cylinder 6, extending from top to bottom. The return liquid channel runs through the inner cylinder 7 and the outer cylinder 6. Through such a reasonable arrangement of the structure, various channels are formed to jointly realize the positive and reverse circulation well washing. The structural design is ingenious.

[0057] In this embodiment 2, the inner cylinder 7 has a groove formed on the outer side of its middle or lower part, and a cavity is formed between the groove and the outer cylinder 6. The inner cylinder outer circulation hole 13 on the upper end face of the inner cylinder 7 connects the space above the inner cylinder 7 and the cavity from top to bottom. The lower part of the outer cylinder 6 is provided with an outer cylinder outlet 14 that connects the cavity and the outside of the outer cylinder 6.

[0058] The inner cylinder's external circulation hole 13 is vertically positioned to facilitate the flow of flushing fluid, while the outer cylinder's outlet 14 is angled downwards, allowing the flushing fluid to create a downward-sloping force as it flows out of the outer cylinder 6, thus improving the flushing effect. The lower part of the outer cylinder 6 can be thickened to better fit the cavity and form the angled outer cylinder outlet 14.

[0059] Example 3

[0060] Based on the above embodiment 2, in this embodiment 3, the middle or lower part of the outer cylinder 6 is provided with a step, and the lower end of the inner cylinder 7 abuts against the step.

[0061] In this embodiment 3, the inner cylinder 7 is positioned inside the outer cylinder 6 by a step, which can prevent installation misalignment. The step can be formed by stamping the inner wall of the outer cylinder 6. The inner diameter of the outer cylinder 6 above the step is larger than the inner diameter at the step. The outer diameter of the lower end of the inner cylinder 7 is similar to the inner diameter of the outer cylinder 6 above the step, which is larger than the inner diameter at the step. The lower end of the inner cylinder 7 is stuck at the step, thus achieving the positioning and installation of the inner cylinder 7 inside the outer cylinder 6.

[0062] Example 4

[0063] Based on any one of the above embodiments 1-3, the inner cylinder 7 and the outer cylinder 6 of this embodiment 4 are connected by connecting screws 5.

[0064] In this embodiment 4, the inner cylinder 7 and the outer cylinder 6 are locked together by connecting screws 5 to prevent the inner cylinder 7 from moving inside the outer cylinder 6 during well cleaning, thus ensuring that each channel is connected according to the structural design.

[0065] Example 5

[0066] Based on the above embodiment 4, in this embodiment 5, the outer cylinder 6 is provided with a plurality of outer cylinder connection positioning holes 16 along its circumference, the inner cylinder 7 is provided with a plurality of inner cylinder connection positioning holes 17 along its circumference, and the connecting screws 5 are provided in a plurality of manner, which are respectively connected to the corresponding outer cylinder connection positioning holes 16 and inner cylinder connection positioning holes 17.

[0067] The multiple circumferentially distributed connecting screws 5 in this embodiment 5 can make the connection between the inner cylinder 7 and the outer cylinder 6 more secure, without causing offset in any direction, thus ensuring the accuracy of the connection.

[0068] Specifically, the outer cylinder connection positioning hole 16 and the inner cylinder connection positioning hole 17 can be correspondingly set in the middle of the outer cylinder 6 and the inner cylinder 7, and their relative positions are preferably between the upper end face of the inner cylinder 7 and the cavity. The outer cylinder connection positioning hole 16 and the inner cylinder connection positioning hole 17 are both threaded holes, which are arranged along the circumference of the inner cylinder 7 and the outer cylinder 6, and the number is at least 2, preferably 4, 6 or 8. The number of connecting screws 5 is the same, and they are threadedly connected to the corresponding outer cylinder connection positioning hole 16 and inner cylinder connection positioning hole 17.

[0069] Example 6

[0070] Based on any one of the above embodiments 1-5, in this embodiment 6, at least one inter-cylinder upper sealing ring 4 is provided between the upper part of the inner cylinder 7 and the outer cylinder 6, and the inter-cylinder upper sealing ring 4 is located above the lower end of the outer circulation hole 13 of the inner cylinder.

[0071] In this embodiment 6, due to the presence of the reverse circulation channel, the drilling fluid needs to flow through the reverse circulation channel to the gap between the inner cylinder 7 and the wellbore. Therefore, an upper sealing ring 4 can be installed between the inner cylinder 7 and the outer cylinder 6 to seal the gap between them. The upper sealing ring 4 is located between the upper end face of the inner cylinder 7 and the connecting screw 5. Sealing at this location can prevent the drilling fluid from corroding the connecting screw 5 when it flows through the gap between the inner cylinder 7 and the outer cylinder 6.

[0072] Example 7

[0073] Based on any one of the above embodiments 1-6, in this embodiment 7, at least one lower sealing ring 8 is provided between the lower part of the inner cylinder 7 and the outer cylinder 6, and the lower sealing ring 8 is located below the liquid outlet 14 of the outer cylinder.

[0074] In this embodiment 7, due to the existence of the reverse circulation channel, the drilling fluid needs to flow through the reverse circulation channel to the gap between the inner cylinder 7 and the wellbore. Therefore, a lower sealing ring 8 can be installed between the inner cylinder 7 and the outer cylinder 6 to seal the gap between them. The lower sealing ring 8 is located between the outer cylinder outlet 14 and the bottom of the inner cylinder 7 to prevent the drilling fluid from flowing out from the gap between the inner cylinder 7 and the outer cylinder 6 below the outer cylinder outlet 14 during reverse circulation.

[0075] Example 8

[0076] like Figure 3-5 As shown, based on any one of the above embodiments 1-7, in this embodiment 8, the inner cylinder outer circulation hole 13 and the outer cylinder liquid outlet 14 are both provided with multiple corresponding circumferentially along the inner cylinder 7 and the outer cylinder 6.

[0077] In this embodiment 8, multiple corresponding inner cylinder external circulation holes 13 and outer cylinder liquid outlets 14 form multiple reverse circulation channels, which are distributed circumferentially, allowing drilling fluid to enter the gap between the cylinder and the wellbore in a circumferential manner, thus avoiding the problem of uneven flushing caused by a single reverse circulation channel or multiple reverse circulation channels together.

[0078] Multiple inner cylinder external circulation holes 13 can be evenly distributed along the circumference of the inner cylinder 7. However, considering that the inner cylinder 7 also needs to be equipped with an inner cylinder return port 12, the preferred solution is to set some of the inner cylinder external circulation holes 13 together to form a group of inner cylinder external circulation holes 13. Then, multiple groups of inner cylinder external circulation holes 13 are evenly distributed along the circumference of the inner cylinder 7, and the inner cylinder return port 12 is set at the interval. In this way, the inner cylinder external circulation holes 13 and the inner cylinder return port 12 are staggered and will not affect each other, and the drilling fluid can flow out more evenly.

[0079] One specific implementation plan, such as Figure 5 As shown, 6-8 inner cylinder external circulation holes 13 form a group of inner cylinder external circulation holes 13. Three groups of inner cylinder external circulation holes 13 are set and evenly distributed along the circumference of the inner cylinder 7. Three inner cylinder return ports 12 are set at three intervals, all set at a 120° angle. The outer cylinder return port 11 and the outer cylinder outlet 14 on the outer cylinder 6 are set accordingly.

[0080] Example 9

[0081] Based on any one of the above embodiments 1-8, in this embodiment 9, the upper end of the outer cylinder 6 is connected to an upper connector 1, and a portion of the positive circulation channel is formed inside the upper connector 1.

[0082] In this embodiment 9, the outer cylinder 6 can be connected to the upper tubing string via the upper connector 1, which facilitates the cylinder extending to the bottom of the wellbore and can also transport drilling fluid.

[0083] Preferably, the upper end of the upper connector 1 is designed with a drill bit or oil casing thread, which can be connected to the upper tubing string.

[0084] Preferably, the outer cylinder 6 is threadedly connected to the upper connector 1. Specifically, the inner wall of the upper end of the outer cylinder 6 is provided with an internal thread, and the outer wall of the lower end of the upper connector 1 is provided with an external thread, so that the two are threadedly connected. The lower end of the upper connector 1 can abut against the upper end of the inner cylinder 7 to make the structure more compact and prevent the inner cylinder 7 from shifting during operation.

[0085] Example 10

[0086] Based on any one of the above embodiments 1-8, in this embodiment 10, the lower end of the outer cylinder 6 is connected to a scooping cylinder 9, and a portion of the positive circulation channel is formed inside the scooping cylinder 9.

[0087] In this embodiment 10, a special scooping cylinder 9 is designed, with the length of the cylinder body and the positive circulation channel extended downwards, which facilitates structural design and improves the rinsing effect.

[0088] Preferably, the scooping cylinder 9 and the outer cylinder 6 are threaded together. Specifically, the inner wall of the upper end of the scooping cylinder 9 is provided with an internal thread, and the outer wall of the lower end of the outer cylinder 6 is provided with an external thread, so that the two are threaded together.

[0089] The upper connector 1, outer cylinder 6, and scooping cylinder 9 form the outer body of this utility model.

[0090] Example 11

[0091] Based on the above embodiment 10, the salvage device in this embodiment 11 is disposed inside the salvage cylinder 9.

[0092] In this embodiment 11, the retrieval device is set in the retrieval cylinder 9, which is located at a lower position. There is enough space above it to accommodate debris, so that the debris at the bottom of the well can be cleaned up and brought out completely.

[0093] Example 12

[0094] Based on any one of the above embodiments 1-11, the switching valve of this embodiment 12 includes a ball seat 3 and a reversing ball 2. The ball seat 3 is connected to the cylinder body and has a liquid inlet channel that runs vertically through it. The reversing ball 2 is used to open or close the liquid inlet channel.

[0095] In this embodiment 12, the switching valve uses a structure of ball seat 3 and reversing ball 2. The ball seat 3 is directly installed in the cylinder. Without the reversing ball 2, the positive circulation channel is open. When the reversing ball 2 is inserted, the positive circulation channel is cut off, making the operation simple.

[0096] The outer wall of the ball seat 3 is designed with external threads, and the inner wall of the upper end of the inner cylinder 7 is provided with internal threads, and the two are connected by threads.

[0097] The ball seat 3 and the inner cylinder 7 constitute the inner body of this utility model. The inner body is inserted from the upper end of the outer cylinder 6 and sits on the step inside the lower end of the outer cylinder 6. The inner cylinder 7 and the outer cylinder 6 are fixed together by connecting screws 5. An upper sealing ring 4 and a lower sealing ring 8 between the cylinders are designed for sealing. When the inner cylinder 7 and the outer cylinder 6 are installed, the outer circulation hole 13 of the inner cylinder and the liquid outlet 14 of the outer cylinder correspond to form the reverse circulation channel of this utility model, and the return liquid outlet 11 of the outer cylinder and the return liquid outlet 12 of the inner cylinder correspond to form the return liquid channel of this utility model.

[0098] The structural design of the reversing ball 2 and the ball seat 3 enables high-volume positive circulation well washing before ball deployment. After the reversing ball 2 is deployed, it is located inside the ball seat 3, blocking the central water hole of the ball seat 3. This causes the circulating fluid to flow only from the outer circulation hole 13 of the inner cylinder to the cavity between the inner cylinder 7 and the outer cylinder 6, and then out from the liquid outlet 14 of the outer cylinder. It enters the annulus between the cylinder and the wellbore (i.e., the gap between the outer wall of the cylinder and the well wall), and then flows in the opposite direction from bottom to top into the retrieval cylinder 9. Finally, it flows back to the annulus between the cylinder and the wellbore along the return liquid outlet 12 of the inner cylinder and the return liquid outlet 11 of the outer cylinder.

[0099] In addition, the switching valve can also be other valve structures that can open or close the positive circulation channel, such as solenoid valves and ball valves. However, since the device needs to enter the bottom of the well, it is inconvenient to use other valve structures for control. The structure of ball seat 3 and reversing ball 2 is a more preferred solution.

[0100] Example 13

[0101] like Figure 1 As shown, based on the above embodiment 12, the liquid inlet channel of this embodiment 13 has an inverted frustum-shaped structure with a large upper diameter and a small lower diameter. The diameter of the reversing ball 2 is smaller than the upper diameter of the liquid inlet channel and larger than the lower diameter of the liquid inlet channel.

[0102] In this embodiment 13, a conical surface is formed at the upper end of the ball seat 3 to receive the reversing ball 2. The reversing ball 2 is inserted and stuck at the lower end of the liquid inlet channel, thereby cutting off the positive circulation channel. The shape design of the ball seat 3 can achieve the purpose of cutting off the positive circulation channel in conjunction with the reversing ball 2. No additional structure is required. The structure is simple, easy to implement, and low in cost.

[0103] Example 14

[0104] Based on the above embodiments 12 or 13, the reversing ball 2 in this embodiment 14 is a soluble ball that will dissolve after a set time of contact with the fluid.

[0105] In this embodiment 14, the design of the soluble reversing ball 2 eliminates the need for additional downhole tool unsealing steps. The soluble ball automatically dissolves upon contact with the fluid within a set time, simplifying the operation process. The dissolution time of the soluble ball upon contact with the fluid can be set through reasonable material design, such as 2 hours, 5 hours, 10 hours, or 24 hours. Existing conventional technologies can be used for specific material selection and preparation processes. Furthermore, the downhole local reverse circulation fishing operation time is also short, and the dissolution time of the soluble ball is sufficient to complete the fishing operation. At the same time, normal circulation can be restored after dissolution.

[0106] This invention differs from existing technologies by innovatively designing a composite reverse circulation device. It employs a nested structure of an inner cylinder 7 and an outer cylinder 6. A soluble ball (reversing ball 2) is pumped into the coiled tubing to precisely block the forward circulation channel, forcing the drilling fluid to redirect from inside the inner cylinder 7 to outside the outer cylinder 6, creating a localized reverse circulation zone. This technology eliminates the need for additional downhole tool unsealing steps; the soluble ball automatically dissolves upon contact with the fluid, simplifying the operation process and overcoming the limitations of traditional multi-run tubing operations. Through an integrated device design, the entire process of "running downhole - sand flushing - single-run replacement - cleaning" can be completed in a single tubing run, significantly shortening operation time and improving wellbore cleaning efficiency.

[0107] Example 15

[0108] Based on any one of the above embodiments 1-14, the lower end of the cylinder in this embodiment 15 is configured with drilling and milling teeth 15.

[0109] In this embodiment, the milling tooth 15 is equivalent to a cutter at the bottom of the cylinder, which makes it easier to move debris at the bottom of the well so that it can enter the retrieval cylinder 9 with the fluid, be retrieved by the retrieval device and brought out of the well.

[0110] Example 16

[0111] Based on any one of the above embodiments 1-15, the salvage device of this embodiment 16 includes a plurality of elastic claws 10, one end of the elastic claw 10 is connected to the cylinder, and the other end extends toward the cylinder and tilts upward.

[0112] The elastic claw 10 in this embodiment 16 is elastic and inclined. Multiple elastic claws 10 form a structure similar to a fishing net. During reverse circulation well washing, debris at the bottom of the well is carried upward from the bottom of the cylinder by the drilling fluid. The elastic claw 10 first deforms to allow the debris to enter the cylinder above the elastic claw 10. After the cleaning is completed, the cylinder is carried upward out of the well. At this time, when the debris falls downward, it is blocked by the elastic claw 10 and kept in the cylinder. Finally, it is carried out of the well along with the cylinder.

[0113] The flexible retrieval claw 10 is preferably a steel wire retrieval claw. The flexible retrieval claw 10 is designed to be tilted upwards, and its position, shape, and tilt angle can be reasonably designed according to the different objects to be retrieved and the diameter of the steel wire.

[0114] Example 17

[0115] Based on the above embodiment 16, the multiple elastic claws 10 of this embodiment 17 are arranged in multiple layers, and each layer of elastic claws 10 is evenly spaced along the circumference of the cylinder.

[0116] In this embodiment 17, a multi-layer elastic retrieval claw 10 is set to achieve multi-layer retrieval, avoid debris falling out, and ensure that all debris at the bottom of the well is retrieved.

[0117] Example 18

[0118] Based on the above embodiment 17, each layer of the elastic claw 10 in this embodiment 18 is provided with at least three, and the elastic claws 10 of adjacent layers are staggered by a set angle to form a spiral claw net structure.

[0119] The spiral-shaped retrieval claw structure of this embodiment 18 ensures that the elastic retrieval claws 10 are evenly and densely distributed inside the cylinder. At the same time, the spiral distribution of multiple elastic retrieval claws 10 can cooperate with each other. Even if debris falls between adjacent elastic retrieval claws 10 on the upper layer, it will be retrieved by the elastic retrieval claws on the lower layer, thereby achieving a better retrieval effect.

[0120] The spiral-shaped retrieval claw mesh structure refers to the distribution of the elastic retrieval claws 10 within the retrieval cylinder 9. For example, if the bottom layer has 3 or 4 elastic retrieval claws 10 evenly distributed circumferentially, and then another layer of elastic retrieval claws 10 is distributed upwards at a certain distance, this layer can also have 3 or 4 elastic retrieval claws 10. However, the circumferentially distributed elastic retrieval claws 10 can be rotated circumferentially by a certain angle relative to the bottom layer, i.e., a set angle, such as 60 degrees, 30 degrees, 20 degrees, etc., and then set upwards sequentially. Each layer of elastic retrieval claws 10 rotates a certain angle relative to the layer below, thus achieving a spiral distribution of the wire rope retrieval claws and a uniform and dense distribution of the elastic retrieval claws 10 within the retrieval cylinder 9, forming a wire rope retrieval claw mesh. Viewed from the bottom upwards, this forms a dense retrieval basket, used to catch objects falling into the retrieval cylinder and thus bring them out of the wellbore.

[0121] In operation, this invention does not initially deploy the reversing ball 2. After the cylinder is lowered into the well with the tubing, the surface pump is started for circulation. Drilling fluid enters the bottom of the well through the positive circulation channel, flushing the bottom of the well with a large-volume positive circulation. Once the small debris is cleared, the reversing ball 2 is deployed into the wellhead and seated in the ball seat 3, blocking the central water hole of the ball seat 3. The pump is then started for circulation again, and the drilling fluid enters the annulus (cavity) between the inner cylinder 7 and outer cylinder 6 from the outer circulation hole 13, and then enters the outer annulus (i.e., the space between the cylinder and the well wall) from the outer cylinder outlet 14. Afterward, the drilling fluid enters the retrieval tube 9 from below (the liquid sprayed from the outer tube outlet 14 can only flow downward due to the pressure of the upper liquid column and enters the retrieval tube 9), then enters the inner tube 7, and finally returns to the outer annulus from the inner tube return port 12 and the outer tube return port 11. The bottom hole debris or foreign matter will be carried into the retrieval tube 9 by the reverse circulation fluid, pass through the elastic retrieval claw 10 and enter the upper retrieval cavity (i.e., the upper part of the retrieval tube 9 and the inner tube 7), and remain in the retrieval cavity, and be discharged from the well with the tube body, thereby achieving a thorough cleaning of the bottom hole.

[0122] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0123] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0124] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0125] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0126] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0127] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A coiled tubing downhole partial reverse circulation well cleaning device, characterized in that, The device includes a cylindrical body, within which a positive circulation channel is formed. The cylindrical body is provided with a switch valve for opening or closing the positive circulation channel. The cylindrical body is provided with a reverse circulation channel connecting the inside of the cylindrical body above the switch valve to the outside of the cylindrical body below the switch valve. The cylindrical body is also provided with a return liquid channel connecting the inside and outside of the cylindrical body and located below the switch valve. The cylindrical body is also provided with a retrieval device located below the return liquid channel.

2. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 1, characterized in that, The cylinder includes an inner cylinder (7) and an outer cylinder (6). The inner cylinder (7) is connected to the middle part of the outer cylinder (6). The positive circulation channel is formed in the upper end of the outer cylinder (6), the inner cylinder (7), and the lower end of the outer cylinder (6). The switch valve is located in the upper end of the inner cylinder (7). The upper end face of the inner cylinder (7) is provided with an inner cylinder outer circulation hole (13) extending downward to the middle or lower part of the inner cylinder. The outer cylinder (6) is provided with an outer cylinder outlet (14) communicating with the inner cylinder outer circulation hole (13). The inner cylinder outer circulation hole (13) and the outer cylinder outlet (14) form the reverse circulation channel. The upper part of the inner cylinder (7) is provided with an inner cylinder return port (12). The outer cylinder (6) is provided with an outer cylinder return port (11) communicating with the inner cylinder return port (12). The inner cylinder return port (12) and the outer cylinder return port (11) form the return channel.

3. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 2, characterized in that, The outer cylinder (6) has a step in the middle or lower part, and the lower end of the inner cylinder (7) abuts against the step.

4. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 2, characterized in that, The inner cylinder (7) and the outer cylinder (6) are connected by connecting screws (5).

5. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 4, characterized in that, The outer cylinder (6) is provided with a plurality of outer cylinder connection positioning holes (16) along its circumference, and the inner cylinder (7) is provided with a plurality of inner cylinder connection positioning holes (17) along its circumference. The connecting screws (5) are provided in a plurality of manner, which are respectively connected to the corresponding outer cylinder connection positioning holes (16) and inner cylinder connection positioning holes (17).

6. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 2, characterized in that, At least one inter-cylinder upper sealing ring (4) is provided between the upper part of the inner cylinder (7) and the outer cylinder (6), and the inter-cylinder upper sealing ring (4) is located above the lower end of the outer circulation hole (13) of the inner cylinder.

7. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 2, characterized in that, At least one lower sealing ring (8) is provided between the lower part of the inner cylinder (7) and the outer cylinder (6), and the lower sealing ring (8) is located below the liquid outlet (14) of the outer cylinder.

8. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 2, characterized in that, The inner cylinder external circulation hole (13) and the outer cylinder liquid outlet (14) are each provided with multiple corresponding circumferential holes along the inner cylinder (7) and the outer cylinder (6).

9. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 2, characterized in that, The upper end of the outer cylinder (6) is connected to an upper connector (1), and a portion of the positive circulation channel is formed inside the upper connector (1).

10. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 2, characterized in that, The lower end of the outer cylinder (6) is connected to a scooping cylinder (9), and a portion of the positive circulation channel is formed inside the scooping cylinder (9).

11. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 10, characterized in that, The salvage device is installed inside the salvage tube (9).

12. A coiled tubing downhole partial reverse circulation well cleaning device according to any one of claims 1 to 11, characterized in that, The switching valve includes a ball seat (3) and a reversing ball (2). The ball seat (3) is connected to the cylinder body and has an inlet channel that runs vertically through it. The reversing ball (2) is used to open or close the inlet channel.

13. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 12, characterized in that, The liquid inlet channel has an inverted frustum-shaped structure with a large diameter at the top and a small diameter at the bottom. The diameter of the reversing ball (2) is smaller than the diameter at the top of the liquid inlet channel and larger than the diameter at the bottom of the liquid inlet channel.

14. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 12, characterized in that, The reversing ball (2) is a soluble ball that will dissolve after a set time of contact with the fluid.

15. A coiled tubing downhole partial reverse circulation well cleaning device according to any one of claims 1 to 11, characterized in that, The lower end of the cylinder is provided with drilling and milling teeth (15).

16. A coiled tubing downhole partial reverse circulation well cleaning device according to any one of claims 1 to 11, characterized in that, The salvage device includes multiple elastic claws (10), one end of which is connected to the cylinder, and the other end extends toward the cylinder and tilts upward.

17. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 16, characterized in that, The multiple elastic claws (10) are arranged in multiple layers, and each layer of elastic claws (10) is evenly spaced along the circumference of the cylinder.

18. The coiled tubing downhole partial reverse circulation well cleaning device according to claim 17, characterized in that, Each layer of the elastic claws (10) has at least three, and the elastic claws (10) of adjacent layers are staggered at a set angle to form a spiral claw net structure.

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