A sandblasting and perforation filling tubular string suitable for continuous tubing and its working method

Abstract

This invention discloses a sandblasting, perforation, and sand-filling tubing string suitable for coiled tubing and its operating method. The tubing string includes a casing and coiled tubing disposed within the casing. An injector and a switching valve are sequentially connected to the lower end of the coiled tubing. The switching valve includes an upper connector, a body, and a lower connector connected sequentially from front to back. A tubular piston is slidably and sealingly connected within the internal cavity of the body. The tubular piston includes a tube body and a piston head disposed at the lower end of the tube body. The piston head is adapted to the outlet of the lower connector. This invention achieves switching between three operating states—sandblasting, perforation, sand flushing, and sand filling—by moving the tubular piston up and down within the switching valve cavity. This invention allows multiple processes to be completed in one tubing run, improving the single-well construction speed and reducing the cost of multiple tubing tripping operations.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction technology, particularly to the field of coiled tubing fracturing in oil and gas wells, and more specifically to a sand-jetting perforation and sand-filling tubing string suitable for coiled tubing and its working method. Background Technology

[0002] Coiled tubing perforation and sand-filled annular fracturing technology is one of the most watched and rapidly developing technologies. This technology has advantages such as precise stratification, pressurized dragging, pressurized tripping and tool changing, the ability to perform pressurized positive circulation at any time, timely treatment of sand blockage, no tools left in the wellbore after construction, and maintenance of the wellbore integrity.

[0003] The utility model patent with publication number CN203978409U and publication date of December 3, 2014 discloses a tubing string for sand-filled layered fracturing process. Theoretically, this tubing string can achieve reverse circulation sand flushing by directly injecting liquid into the annulus of the casing under the action of the tail guide check valve. However, due to the small diameter of the coiled tubing and the large annulus outside the coiled tubing, it is difficult to flush sand into the coiled tubing. The effect of reverse circulation sand flushing is not good. Moreover, the reverse circulation liquid is carried out through the coiled tubing, which can easily form sand blockage in the tubing. Summary of the Invention

[0004] To address the problems and defects in the existing technology, the present invention provides a sandblasting and perforation filling tubing string suitable for continuous tubing and its working method. The tubing string of the present invention can perform sandblasting and perforation, as well as sand filling operations, and can also perform rapid positive sand flushing. The device has a good sand flushing effect and eliminates the situation of sand blockage in continuous tubing.

[0005] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0006] A sandblasting and perforation filling string suitable for continuous tubing, the string including a casing and a continuous tubing disposed within the casing, the lower end of the continuous tubing being connected to a safety joint, and the lower end of the safety joint being connected to an injector via a pipe, the lower end of the injector being connected to a switching valve, the switching valve including an upper connector, a body, and a lower connector connected sequentially from front to back, a tubular piston being slidably and sealingly connected within the internal cavity of the body, the tubular piston including a tube body and a piston head, the upper end of the tube body communicating with the inlet of the upper connector, the piston head being disposed at the lower end of the tube body, the piston head being adapted to the outlet of the lower connector, and a [missing information - likely a design feature] being provided on the outer wall of the tube body. The tube has a first annular protrusion and a second annular protrusion on its inner wall. When the first and second annular protrusions mate, they form a liquid accumulation chamber located above the switch valve between the outer wall of the tube and the inner wall of the body. The inner wall of the lower connector has a third annular protrusion. When the third annular protrusion mates with the first annular protrusion, it forms a sealed gas storage chamber located below the switch valve between the outer wall of the tube and the inner wall of the body. The upper end of the tube has a liquid inlet slit communicating with the liquid accumulation chamber, and the lower end has an opening groove communicating with the lower connector. The first annular protrusion has an air inlet channel communicating with the gas storage chamber, and a one-way valve core is installed in the air inlet channel.

[0007] Preferably, the air intake end of the air intake channel is provided with a threaded hole, and a sealing bolt is provided in the threaded hole.

[0008] Preferably, the piston head is provided with a first conical surface, and the inner wall of the lower connector is provided with a second conical surface corresponding to the first conical surface.

[0009] Preferably, the width of the liquid inlet gap is less than 0.1 mm.

[0010] Preferably, a liquid guide tube is provided between the upper end of the tube and the second annular protrusion on the inner wall of the body.

[0011] Preferably, the third annular protrusion is slidably sealed to the outer wall of the tube, and a sealing element is provided between the two.

[0012] Preferably, the first annular protrusion is slidably and sealingly connected to the cavity wall of the body, and a sealing element is provided between the two.

[0013] A method for operating a sand-blasting perforation and sand-filling tubing string suitable for coiled tubing involves first running the tubing string downhole. The tubing string includes a casing and coiled tubing installed within the casing. A safety joint is connected to the lower end of the coiled tubing. An injector is connected to the lower end of the safety joint via a pipe. The lower end of the injector is connected to a switching valve. The injector is aligned with the location to be modified. The injection orifice on the injector is normally open. The inlet and outlet of the switching valve are also normally open. The gas storage chamber of the switching valve is filled with inert gas.

[0014] When liquid is introduced into the continuous tubing, part of the liquid enters the annulus of the casing through the injection hole on the injector, and part of the liquid enters the tubular piston through the inlet at the top of the switch valve. Part of the liquid entering the tubular piston enters the liquid accumulation chamber through the inlet gap at the top, pushing the tubular piston toward the lower connector. Another part of the liquid flows out through the fluid channel inside the tubular piston, through the opening groove at the bottom of the tube body, and finally enters the annulus of the casing through the outlet on the lower connector.

[0015] During sandblasting and perforation operations, sand fluid is injected into the coiled tubing to increase the ground pump pressure and the sand fluid discharge rate in the tubing. The tubular piston is pushed down to its limit position, and the piston head blocks the outlet on the lower connector. During perforation, the sand fluid is injected from the coiled tubing and ejected from the injection hole on the injector.

[0016] During sand filling operations, sand fluid is injected into the coiled tubing, and the surface pump pressure and the sand fluid discharge rate in the tubing are reduced. The gas in the gas storage chamber pushes the tubular piston upward, and the outlet on the lower connector is opened. During sand filling, part of the sand fluid enters the annulus of the casing through the injection hole on the injector, and part of the sand fluid enters the annulus of the casing through the outlet on the lower connector.

[0017] During sand flushing operations, flushing fluid is injected into the coiled tubing, and the ground pump pressure and the flushing fluid discharge rate in the coiled tubing are reduced. The gas in the gas storage chamber pushes the tubular piston upward, and the outlet on the lower connector is opened. During sand flushing, part of the flushing fluid enters the annulus of the casing through the injection hole on the ejector, and part of the fluid enters the annulus of the casing through the outlet on the lower connector.

[0018] Preferably, sandblasting and perforation are performed when the ground pump pressure is increased to 40~60 MPa and the sand discharge rate in the coiled tubing reaches 0.65~0.8 m3 / min.

[0019] Preferably, sand filling is carried out when the ground pump pressure drops below 25 MPa and the sand fluid in the coiled tubing drops to a flow rate of 0.5 m³ / min.

[0020] The beneficial effects of this invention are:

[0021] (1) This invention enables multiple processes to be completed in one tubing string, improving the construction speed of a single well, reducing the cost of multiple tubing trips, improving the work efficiency of operators, reducing their labor intensity, extending the service life of equipment, reducing the fatigue of the coiled tubing, and reducing downtime during construction. It also reduces the amount of workover fluid used, thus protecting the environment.

[0022] (2) By filling the switching valve with inert gas, the position of the tubular piston in the switching valve can be changed by changing the ground pump pressure, thereby switching the working state of the switching valve. Therefore, it can adapt to various cyclic operations, has a wide range of applications, and has broad prospects for promotion. Attached Figure Description

[0023] The foregoing and hereinafter detailed description of the invention becomes clearer when read in conjunction with the following drawings, in which:

[0024] Figure 1 This is a schematic diagram of the internal structure of the switching valve of the present invention;

[0025] Figure 2 This is a three-dimensional schematic diagram of the tubular piston of the present invention;

[0026] Figure 3 This is a schematic diagram of the internal structure of the tubular piston of the present invention;

[0027] Figure 4 This is a schematic diagram of the process tubing of the present invention;

[0028] In the picture:

[0029] 1. Upper connector; 2. Body; 3. Lower connector; 4. Tubular piston; 5. First annular protrusion; 6. Second annular protrusion; 7. Liquid accumulation chamber; 8. Third annular protrusion; 9. Gas storage chamber; 10. Liquid inlet gap; 11. Opening groove; 12. Air inlet channel; 13. One-way valve core; 14. Threaded hole; 15. First conical surface; 16. Second conical surface; 17. Liquid guide tube; 18. Sleeve; 19. Continuous tubing; 20. Safety joint; 21. Injector; 22. Switch valve; 401. Pipe body; 402. Piston head. Detailed Implementation

[0030] This invention proposes a sand-blasting perforation and sand-filling tubing string suitable for coiled tubing, and its operating method. It aims to achieve a single-trip drilling operation during multi-cluster sand-blasting perforation, sand-filling temporary plugging, staged fracturing, and sand-flushing operations in horizontal wells. This invention completes multiple processes in a single tubing run, increasing the construction speed of a single well, reducing the cost of multiple tubing trips, improving operator efficiency, reducing operator labor intensity, extending equipment life, reducing coiled tubing fatigue, and minimizing downtime. Furthermore, it reduces the use of workover fluid, protecting the environment.

[0031] The technical solutions for achieving the objectives of this invention will be further illustrated below through specific embodiments. It should be noted that the technical solutions claimed by this invention include, but are not limited to, the following embodiments.

[0032] To facilitate understanding of this embodiment, the following explanation and description will first be given of a sandblasting and perforation filling sand column suitable for continuous tubes disclosed in this embodiment of the invention.

[0033] This embodiment discloses a sandblasting and perforation filling sand-filling string suitable for continuous tubing, as shown in the attached instruction manual. Figure 1-4 The tubing string includes a casing 18 and a continuous tubing 19 disposed within the casing 18. A safety connector 20 is connected to the lower end of the continuous tubing 19. An injector 21 is connected to the lower end of the safety connector 20 via a pipe. The lower end of the injector 21 is connected to the switching valve 22. The switching valve 22 includes an upper connector 1, a body 2, and a lower connector 3 connected sequentially from front to back. The upper connector 1, body 2, and lower connector are all hollow tubular structures with openings at both ends. When connected sequentially, their internal cavities are interconnected. The opening at the upper end of the upper connector constitutes the inlet of the switching valve 22, and the opening at the tail end of the lower connector constitutes... The outlet of the switching valve 22 is connected to the upper connector 1 and the body 2 by a thread, with a seal at the connection. The lower connector 3 is also connected to the body 2 by a thread, and a seal is also provided at the connection. A tubular piston 4 is slidably and sealingly connected in the internal cavity of the body 2. The tubular piston 4 can move along the axis of the switching valve 22 in the cavity. The tubular piston 4 includes a tube body 401 and a piston head 402. The tube body 401 is also hollow inside and open at both ends. The internal cavity of the tube body 401 forms a fluid channel. The opening at the upper end of the tube body 401 communicates with the inlet of the upper connector 1. The piston head 402 is located on the tube body 401. The lower end of 01 is a cylindrical solid structure that blocks the opening at the lower end of the tube body 401. The size and shape of the piston head 402 are adapted to the liquid outlet of the lower connector 3, and the piston head 402 is used to block the liquid outlet. Further, a first annular protrusion 5 is provided on the outer wall of the tube body 401, and a second annular protrusion 6 is provided on the inner wall of the body 2. After the first annular protrusion 5 and the second annular protrusion 6 cooperate, a liquid accumulation chamber 7 located above the switch valve 22 is formed between the outer wall of the tube body 401 and the inner wall of the body 2. A third annular protrusion 8 is provided on the inner wall of the lower connector 3. After the third annular protrusion 8 cooperates with the first annular protrusion 5, a liquid accumulation chamber 7 is formed between the outer wall of the tube body 401 and the inner wall of the body 2. A sealed gas storage chamber 9 is formed between the outer wall of the tube body 401 and the inner wall of the body 2, located below the switch valve 22; the upper end of the tube body 401 is provided with a liquid inlet slit 10, which is connected to the liquid accumulation chamber 7 above the switch valve 22; the lower end of the tube body 401 is provided with an opening groove 11, which is connected to the lower connector 3; the first annular protrusion 5 is provided with an air inlet channel 12 along the axial direction, which is connected to the gas storage chamber 9; a one-way valve core 13 is provided in the air inlet channel 12, which is fixed in the air inlet channel 12 by a one-way valve bolt; the one-way valve bolt is provided with a channel for connecting to the gas storage chamber 9.

[0034] In this embodiment, it should be noted that the direction from front to back refers to the flow direction of the fluid inside the switching valve 22.

[0035] In this embodiment, the first annular protrusion 5 is slidably and sealingly connected to the inner wall of the body 2, and an annular seal is provided between them. The second annular protrusion 6 is slidably and sealingly connected to the outer wall of the tube 401, and an annular seal is also provided between them. Finally, the first annular protrusion 5, the second annular protrusion 6, the inner wall of the body 2, and the outer wall of the tube 401 surround the liquid accumulation chamber 7 in the cavity of the body 2. The liquid accumulation chamber 7 is located at the upper part of the switch valve.

[0036] In this embodiment, the third annular protrusion 8 is slidably sealed to the outer wall of the tube body 401, and an annular seal is provided between the two. The first annular protrusion 5, the third annular protrusion 8, the inner wall of the body 2 and the outer wall of the tube body 401 surround the air storage cavity 9 in the cavity of the body 2. The air storage cavity 9 is located at the lower part of the switch valve.

[0037] In a preferred embodiment, the width of the liquid inlet slit 10 provided on the pipe body 401 is no more than 0.1 mm. This ensures that when sand liquid is introduced into the switch valve, only liquid can flow into the liquid accumulation chamber 7 from the liquid inlet slit 10, while the solid substances in the sand liquid are blocked by the slit, thus playing a certain filtering role.

[0038] In a preferred embodiment, in order to ensure the sealing performance of the gas storage chamber 9 and prevent the gas in the gas storage chamber 9 from overflowing outward after the one-way valve core fails, the gas inlet end of the gas inlet channel 12 is provided with a threaded hole 14, and a sealing bolt is provided in the threaded hole 14. The sealing bolt realizes secondary sealing of the gas storage chamber 9.

[0039] In a preferred embodiment, the piston head 402 is provided with a first conical surface 15, and the inner wall of the lower connector 3 is provided with a second conical surface 16 corresponding to the first conical surface 15. The first conical surface 15 and the second conical surface 16 are adapted to each other, so that the piston head can better seal the liquid outlet of the lower connector 3 and improve the effect of sandblasting orifice.

[0040] In a preferred embodiment, in order to increase the sealing performance between the upper end of the tubular piston 4 and the inner wall of the body 1 and prevent fluid from flowing directly into the liquid accumulation chamber 7 from the gap between them, a liquid guide tube 17 is embedded between the upper end of the tube body 401 and the second annular protrusion 6 on the inner wall of the body 2. The lower end of the liquid guide tube 17 is connected to the upper end of the body 2 by a thread, and a seal is installed at the connection.

[0041] In this embodiment, the one-way valve core 13 is a conventional valve core. The end face of the valve core is in contact with the inner end face of the channel of the one-way valve bolt. There should be a certain distance between the valve core and the one-way valve bolt to facilitate the back-and-forth movement of the valve core. During the installation process, the valve core should be installed first, and then the one-way valve bolt should be tightened.

[0042] In this embodiment, the installation method of the switch valve 22 is as follows: First, the lower connector 3 is threadedly connected to the body 2; then, a tubular piston 4 is installed in the lower connector 3 and the body 2; next, a conventional high-pressure rubber hose is connected to the threaded hole 14 at the air inlet end of the air inlet channel 12, and inert gas is slowly filled into the gas storage chamber 9 of the switch valve. The inert gas can be nitrogen or other gases, and the filling pressure is 5~25 MPa; after the gas filling is completed, the liquid guide tube 4 and the upper connector 5 are finally installed to complete the assembly of the entire switch valve 22.

[0043] Based on the same inventive concept, embodiments of the present invention also propose a working method for sandblasting and perforating sand-filled tubing suitable for continuous tubes, the method being as follows:

[0044] First, the process tubing is lowered into the well. The structure of the tubing is shown in the attached instruction manual. Figure 4 It includes a casing 18 and a continuous oil pipe 19 disposed within the casing 18. The lower end of the continuous oil pipe 19 is connected to a safety joint 20. The lower end of the safety joint 20 is connected to an injector 21 via a pipe. The injection port on the injector 21 is normally open. The injector 21 is aligned with the location to be modified. The lower end of the injector 21 is connected to the switching valve 22. The inlet and outlet of the switching valve 22 are normally open. The gas storage chamber 9 of the switching valve 22 is pre-filled with inert gas. The pressure of the inert gas is generally 12-18 MPa, and cannot exceed 18 MPa.

[0045] When liquid is injected from the coiled tubing 19, a portion of the liquid enters the annulus of the casing 18 through the injection hole on the injector 21, and a portion of the liquid enters the tubular piston 4 through the inlet at the upper end of the switching valve 22. A portion of the liquid entering the tubular piston 4 enters the accumulation chamber 7 through the inlet gap 10 at the upper end, thereby pushing the tubular piston 4 toward the lower connector 3. Another portion of the liquid flows out through the fluid channel inside the tubular piston 4 through the opening groove 11 at the lower end of the tube body 401 to the lower connector 3, and finally enters the annulus of the casing 18 through the outlet on the lower connector 3.

[0046] In this embodiment, the volumes of the liquid accumulation chamber 7 and the gas storage chamber 9 change as the tubular piston 4 moves up and down. For example, when the tubular piston 4 moves downward toward the lower connector 3, the volume of the gas storage chamber 9 gradually decreases, while the volume of the liquid accumulation chamber 7 gradually increases. When the tubular piston 4 moves downward toward the lower connector 3, the gas filling the gas storage chamber 9 is compressed and stored, and the gas pressure inside the chamber gradually increases. When the liquid flow rate into the inlet decreases, the gas in the gas storage chamber 9 releases energy, pushing the tubular piston 4 toward the upper connector 1.

[0047] When the ground pump pressure is increased to 40~60 MPa and the sand flow rate in the coiled tubing 19 reaches 0.65~0.8 m³ / min, sandblasting and perforation operations will be carried out. The tubular piston 4 is pushed down to the limit position by the sand, at which point the piston head 402 completely blocks the outlet on the lower connector 3, and the outlet of the switch valve 22 is sealed. During perforation, the sand is injected from the coiled tubing 19 and finally ejected from the injection hole on the injector 21.

[0048] When the ground pump pressure is reduced to below 25 MPa, and the sand filling operation is carried out when the sand fluid in the coiled tubing 19 is reduced to a flow rate of 0.5 m³ / min, the gas in the gas storage chamber 9 pushes the tubular piston 4 to move towards the upper connector 1. The piston head 402 disengages from the outlet of the lower connector 3, and the outlet of the switch valve 22 is opened. During sand filling, the sand fluid is injected from the coiled tubing 19. Part of it enters the annulus of the casing 18 through the injection hole on the injector 21, and part of it enters the annulus of the casing 18 through the outlet on the lower connector 3.

[0049] In this embodiment, if sand flushing is required, workover fluid or sand flushing fluid is introduced into the coiled tubing 19, while the pump pressure is controlled below 25 MPa and the sand flushing fluid discharge rate in the coiled tubing 19 is less than 0.5 m³ / min. Sand flushing can then be carried out. Similarly, after the sand flushing fluid is injected from the coiled tubing 19, part of it enters the annulus of the casing 18 through the injection hole on the injector 21, and part of it enters the annulus of the casing 18 through the outlet on the lower connector 3.

[0050] By controlling the pressure during sand filling and flushing operations, we maintain the pump pressure below 25 MPa and the discharge rate below 0.5 m³ / min. During fracturing operations, we increase the surface pump pressure to 40-60 MPa and the discharge rate to 0.65-0.8 m³ / min for sand blasting and perforation. This reduces the difficulty of removing the tubing for sand flushing and replacing it, which was previously a challenge.

[0051] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0052] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A sandblasting and perforation filling tubing string suitable for continuous tubing, comprising a casing (18) and a continuous tubing (19) disposed within the casing (18), wherein a safety joint (20) is connected to the lower end of the continuous tubing (19), and an injector (21) is connected to the lower end of the safety joint (20) via a pipe, and a switching valve (22) is connected to the lower end of the injector (21), wherein the switching valve (22) comprises an upper connector (1), a body (2), and a lower connector (3) connected sequentially from front to back, characterized in that, A tubular piston (4) is slidably and sealed within the internal cavity of the main body (2). The tubular piston (4) includes a tube body (401) and a piston head (402). The upper end of the tube body (401) is connected to the liquid inlet of the upper connector (1), and the piston head (402) is located at the lower end of the tube body (401). The piston head (402) is adapted to the liquid outlet of the lower connector (3). A first annular protrusion (5) is provided on the outer wall of the tube body (401), and a second annular protrusion (6) is provided on the inner wall of the main body (2). After the first annular protrusion (5) and the second annular protrusion (6) are engaged, a seal is formed between the outer wall of the tube body (401) and the inner wall of the main body (2). A liquid accumulation chamber (7) is formed at the top of the switch valve; the inner wall of the lower connector (3) is provided with a third annular protrusion (8), and after the third annular protrusion (8) cooperates with the first annular protrusion (5), a sealed gas storage chamber (9) is formed between the outer wall of the pipe body (401) and the inner wall of the body (2) at the bottom of the switch valve; the upper end of the pipe body (401) is provided with a liquid inlet gap (10) communicating with the liquid accumulation chamber (7), and the lower end is provided with an opening groove (11) communicating with the lower connector (3); the first annular protrusion (5) is provided with an air inlet channel (12) communicating with the gas storage chamber (9), and a one-way valve core (13) is provided in the air inlet channel (12).

2. The sandblasting and perforation filling tubular string suitable for continuous tubing according to claim 1, characterized in that, The air intake end of the air intake channel (12) is provided with a threaded hole (14), and a sealing bolt is provided in the threaded hole (14).

3. A sandblasting and perforation filling tubular string suitable for continuous tubing according to claim 1, characterized in that, The piston head (402) is provided with a first conical surface (15), and the inner wall of the lower connector (3) is provided with a second conical surface (16) corresponding to the first conical surface (15).

4. A sandblasting and perforating sand-filling tubing string suitable for continuous tubing according to claim 1, characterized in that, The width of the liquid inlet gap (10) is less than 0.1 mm.

5. A sandblasting and perforating sand-filling tubing string suitable for continuous tubing according to claim 1, characterized in that, A liquid guide tube (17) is provided between the upper end of the tube (401) and the second annular protrusion (6) on the inner wall of the body (2).

6. The working method for a sandblasting and perforation filling sand-filled tubing string suitable for continuous tubing according to claim 1, characterized in that, The tubing string is lowered downhole, and the injector (21) is aligned with the location to be modified. The injection port on the injector (21) is normally open, and the inlet and outlet of the switch valve (22) are normally open. The gas storage chamber (9) of the switch valve (22) is filled with inert gas. When the tubing carries sand fluid, a portion of the fluid enters the annulus of the casing (18) through the injection hole on the injector (21), and a portion of the fluid enters the tubular piston (4) through the inlet at the upper end of the switch valve (22). A portion of the fluid entering the tubular piston (4) enters the accumulation chamber (7) through the inlet gap (10) at the upper end, pushing the tubular piston (4) toward the lower connector (3). Another portion of the fluid flows out through the fluid channel inside the tubular piston (4) through the opening groove (11) at the lower end of the pipe body (401) to the lower connector (3), and finally enters the annulus of the casing (18) through the outlet on the lower connector (3). Increase the ground pump pressure and the liquid discharge in the continuous tubing (19) to perform sandblasting and perforation. The tubular piston (4) moves down to the limit position, and the piston head (402) blocks the liquid outlet on the lower connector (3). During perforation, the sand liquid is injected from the continuous tubing (19) and ejected from the injection hole on the injector (21). The ground pump pressure and the liquid discharge in the coiled tubing (19) are reduced to carry out sand filling operations. The gas in the gas storage chamber (9) pushes the tubular piston (4) upward, and the liquid outlet on the lower connector (3) is opened. When filling sand, the sand liquid is injected from the coiled tubing (19). Part of it enters the annulus of the casing (18) through the injection hole on the injector (21), and part of it enters the annulus of the casing (18) through the liquid outlet on the lower connector (3). Reduce the ground pump pressure and the liquid discharge in the coiled tubing (19) to carry out sand flushing operation. Inject sand flushing fluid into the coiled tubing (19). During sand flushing, part of the liquid enters the annulus of the casing (18) through the injection hole on the injector (21), and part of the liquid enters the annulus of the casing (18) through the liquid outlet on the lower connector (3).

7. The working method for a sandblasting and perforation filling sand-filling tubing suitable for continuous tubing according to claim 6, characterized in that, When the ground pump pressure is increased to 40~60Mpa and the liquid discharge rate in the continuous tubing (19) reaches 0.65~0.8m3 / min, sandblasting and perforation are carried out.

8. The working method for a continuous tube blasting and perforation sand-filling string according to claim 6, characterized in that, When the ground pump pressure drops below 25MPa and the liquid discharge rate in the coiled tubing (19) drops to 0.5m3 / min, sand filling or flushing operations should be carried out.

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