Sand blasting perforation sand filling pipe column suitable for continuous pipe and working method of sand blasting perforation sand filling pipe column

Abstract

The invention discloses a sand blasting perforation sand filling pipe column suitable for a coiled tubing and a working method.The pipe column comprises a sleeve and the coiled tubing arranged in the sleeve, the lower end of the coiled tubing is sequentially connected with an ejector and a switch valve, and the switch valve comprises an upper connector, a body and a lower connector which are sequentially connected from front to back; a tubular piston is connected in an inner cavity of the body in a sliding and sealing mode, the tubular piston comprises a tube body and a piston head arranged at the lower end of the tube body, and the piston head is matched with a liquid outlet of the lower connector. The three working states of sand blasting perforation, sand washing and sand filling are switched. A plurality of procedures can be completed through one pipe column, the single well construction speed is increased, and the cost of multiple times of pipe pulling operation can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas exploitation, in particular to the field of oil and gas well continuous pipe sand filling fracturing, and more specifically to a sandblasting perforating sand filling pipe column suitable for continuous pipe and a working method thereof. Background Art

[0002] Coiled tubing sandblasting perforation and sand filling annular fracturing technology is one of the most concerned and fastest developing technologies. This technology has the advantages of accurate stratification, pressure dragging, pressure tripping and tool replacement, pressure positive circulation at any time, timely treatment of sand plugging, no tools left in the wellbore after construction, and can keep the wellbore intact.

[0003] The utility model patent with publication number CN203978409U and publication date December 3, 2014 discloses a pipe string for sand-filled layered fracturing process. Under the action of the tail guide check valve, the pipe string can theoretically realize reverse circulation sand flushing operation by directly injecting liquid into the annulus of the casing. However, since the diameter of the continuous tubing is very small and the annulus outside the continuous tubing is large, it is difficult to flush sand into the continuous tubing, and the effect of reverse circulation sand flushing is not good. In addition, the reverse circulation liquid is carried out through the continuous tubing, which is very likely to form sand blockage in the tubing. Summary of the invention

[0004] In view of the problems and defects existing in the above-mentioned prior art, the present invention provides a sandblasting perforating sand filling pipe string suitable for a coiled tubing and a working method thereof. The pipe string of the present invention can perform both sandblasting perforating and sand filling operations, and can also perform positive sand flushing quickly. The device has a good sand flushing effect and prevents sand blockage in the coiled tubing.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows: A sandblasting perforating sand filling pipe string suitable for a continuous pipe, the pipe string comprises a casing and a continuous oil pipe arranged in the casing, the lower end of the continuous oil pipe is connected with a safety joint, the lower end of the safety joint is connected with an injector through a pipeline, the lower end of the injector is connected with the switch valve, the switch valve comprises an upper joint, a body and a lower joint connected in sequence from front to back, a tubular piston is slidably and sealably connected in the internal cavity of the body, the tubular piston comprises a pipe body and a piston head, the upper end of the pipe body is communicated with the liquid inlet of the upper joint, the piston head is arranged at the lower end of the pipe body, the piston head is adapted to the liquid outlet of the lower joint, and a valve is arranged on the outer wall of the pipe body. A first annular protrusion is provided, and a second annular protrusion is provided on the inner wall of the main body. After the first annular protrusion cooperates with the second annular protrusion, a liquid accumulation cavity located at the upper part of the switch valve is formed between the outer wall of the tube body and the inner wall of the main body; a third annular protrusion is provided on the inner wall of the lower joint. After the third annular protrusion cooperates with the first annular protrusion, a closed air storage cavity located at the lower part of the switch valve is formed between the outer wall of the tube body and the inner wall of the main body; the upper end of the tube body is provided with a liquid inlet gap connected with the liquid accumulation cavity, and the lower end is provided with an open groove connected with the lower joint; the first annular protrusion is provided with an air intake channel connected with the air storage cavity, and a one-way valve core is provided in the air intake channel.

[0006] Preferably, a threaded hole is provided at the air inlet end of the air inlet passage, and a sealing bolt is provided in the threaded hole.

[0007] Preferably, the piston head is provided with a first conical surface, and the inner wall of the lower joint is provided with a second conical surface corresponding to the first conical surface.

[0008] Preferably, the width of the liquid inlet gap is less than 0.1 mm.

[0009] Preferably, a liquid guide tube is provided between the upper end of the tube body and the second annular protrusion on the inner wall of the body.

[0010] Preferably, the third annular protrusion is slidably and sealingly connected to the outer wall of the tube body, and a sealing member is provided therebetween.

[0011] Preferably, the first annular protrusion is slidably and sealingly connected to the cavity wall of the body, and a sealing member is provided therebetween.

[0012] A working method for a sandblasting perforating sand filling pipe string suitable for a coiled pipe, firstly, the pipe string is lowered into the well, the process pipe string comprises a casing and a coiled oil pipe arranged in the casing, the lower end of the coiled oil pipe is connected with a safety joint, the lower end of the safety joint is connected with an injector through a pipeline, the lower end of the injector is connected with the switch valve, and the injector is aligned with a position requiring modification; the injection hole on the injector is in a normally open state, the liquid inlet and the liquid outlet of the switch valve are in a normally open state, and the gas storage chamber of the switch valve is filled with an inert gas; When liquid is introduced into the coiled 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 liquid inlet at the upper end of the switch valve. Part of the liquid entering the tubular piston enters the liquid accumulation cavity through the liquid inlet gap at the upper end, pushing the tubular piston to move toward the lower joint, and another part of the liquid passes through the fluid channel in the tubular piston, flows out to the lower joint through the open groove at the lower end of the tube body, and finally enters the annulus of the casing through the liquid outlet on the lower joint. During sandblasting and perforating, sand liquid is injected into the coiled tubing to increase the surface pump pressure and the displacement of sand liquid in the tubing. The tubular piston is pushed down to the limit position, and the piston head blocks the liquid outlet on the lower joint. During perforating, sand liquid is injected from the coiled tubing and ejected from the ejection hole on the ejector. During sand filling operation, sand liquid is injected into the coiled tubing, and the surface pump pressure and the sand liquid displacement in the tubing are reduced. The gas in the gas storage cavity pushes the tubular piston upward, and the liquid outlet on the lower joint is opened. During sand filling, part of the sand liquid enters the annulus of the casing through the injection hole on the injector, and part of the sand liquid enters the annulus of the casing through the liquid outlet on the lower joint. During sand flushing operation, sand flushing liquid is injected into the coiled tubing, and the surface pump pressure and the displacement of the sand flushing liquid in the coiled tubing are reduced. The gas in the air storage chamber pushes the tubular piston upward, and the liquid outlet on the lower joint is opened. During sand flushing, part of the sand flushing liquid enters the annulus of the casing through the injection hole on the injector, and part of the sand flushing liquid enters the annulus of the casing through the liquid outlet on the lower joint.

[0013] Preferably, sandblasting and perforating are performed when the surface pump pressure increases to 40-60 MPa and the sand and liquid displacement in the coiled tubing reaches 0.65-0.8 m3 / min.

[0014] Preferably, the sand filling operation is performed when the surface pump pressure drops below 25 MPa and the sand liquid in the coiled tubing drops to a displacement of 0.5 m3 / min.

[0015] Beneficial effects of the present invention: (1) The present invention can complete multiple processes in one trip of the tubing string, thereby increasing the speed of single well construction and reducing the cost of multiple trips. At the same time, it also improves the work efficiency of operators, reduces the labor intensity of operators, prolongs the service life of equipment, reduces the fatigue of coiled tubing, and reduces the phenomenon of construction downtime. It also reduces the use of well repair fluid in construction and protects the environment.

[0016] (2) The present invention can change the position of the tubular piston in the switch valve by filling the switch valve with inert gas and changing the surface pump pressure, thereby switching the working state of the switch valve. Therefore, it can adapt to various types of circulation operations, has a wide range of applications, and has broad prospects for promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The foregoing and following detailed description of the present invention will become more apparent when read in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the internal structure of the switch valve of the present invention; Figure 2 It is a three-dimensional schematic diagram of a tubular piston of the present invention; Figure 3 It is a schematic diagram of the internal structure of the tubular piston of the present invention; Figure 4 It is a schematic diagram of the process column of the present invention; In the figure: 1. Upper joint; 2. Main body; 3. Lower joint; 4. Tubular piston; 5. First annular protrusion; 6. Second annular protrusion; 7. Liquid accumulation chamber; 8. Third annular protrusion; 9. Air storage chamber; 10. Liquid inlet gap; 11. Open groove; 12. Air inlet channel; 13. One-way valve core; 14. Threaded hole; 15. First cone surface; 16. Second cone surface; 17. Liquid guide tube; 18. Casing; 19. Continuous oil pipe; 20. Safety joint; 21. Injector; 22. Switch valve; 401. Tube body; 402. Piston head. DETAILED DESCRIPTION

[0018] The present invention proposes a sandblasting perforating and sand filling pipe string suitable for coiled tubing and a working method thereof, aiming to realize a one-trip drilling operation technology in the process of multi-cluster sandblasting perforating, sand filling temporary plugging staged fracturing and sand flushing operations in horizontal wells. The present invention completes multiple processes in one trip of the pipe string, improves the construction speed of a single well, and can reduce the cost of multiple pipe pulling and lowering operations. At the same time, it also improves the work efficiency of operators, reduces the labor intensity of operators, prolongs the service life of equipment, reduces the fatigue of coiled tubing, and reduces the phenomenon of construction stoppage. It also reduces the use of well repair fluid in construction and protects the environment.

[0019] The technical solution for achieving the purpose of the present invention is further described below by means of specific embodiments. It should be noted that the technical solution claimed for protection by the present invention includes but is not limited to the following embodiments.

[0020] In order to facilitate the understanding of this embodiment, firstly, a sandblasting perforation sand filling pipe string applicable to a coiled pipe disclosed in an embodiment of the present invention is explained and illustrated.

[0021] This embodiment discloses a sandblasting perforation flushing sand filling pipe string suitable for continuous pipe, Figure 1-4The tubular column includes a casing 18 and a coiled tubing 19 disposed in the casing 18. The lower end of the coiled tubing 19 is connected to a safety joint 20. An injector 21 is connected to the lower end of the safety joint 20 through a pipeline. The lower end of the injector 21 is connected to the switch valve 22. The switch valve 22 includes an upper joint 1, a body 2 and a lower joint 3 connected in sequence from front to back. The upper joint 1, the body 2 and the lower joint are all hollow pipe structures with openings at both ends. After the three are connected in sequence, the internal cavity is connected. The opening provided at the upper end of the upper joint constitutes the liquid inlet of the switch valve 22, and the opening provided at the tail of the lower joint constitutes The liquid outlet of the switch valve 22 is connected by a thread between the upper joint 1 and the body 2, and a seal is installed at the connection. The lower joint 3 and the body 2 are also connected by a thread, and a seal is also provided at the connection. A tubular piston 4 is slidably and sealably connected to the internal cavity of the body 2, and the tubular piston 4 can move along the axial direction of the switch 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 constitutes a fluid channel. The opening at the upper end of the tube body 401 is connected to the liquid inlet of the upper joint 1, and the piston head 402 is arranged on the tube body 4 The lower end of 01 is a cylindrical solid structure, which blocks the opening of the lower end of the tube body 401. The size and shape of the piston head 402 are compatible with the liquid outlet of the lower joint 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 main body 2. After the first annular protrusion 5 cooperates with the second annular protrusion 6, a liquid accumulation cavity 7 located at the upper part of the switch valve 22 is formed between the outer wall of the tube body 401 and the inner wall of the main body 2; the inner wall of the lower joint 3 is provided with a third annular protrusion 8, and after the third annular protrusion 8 cooperates with the first annular protrusion 5, An enclosed air storage chamber 9 located at the lower part of the switch valve 22 is formed between the outer wall of the tube body 401 and the inner wall of the main body 2; a liquid inlet gap 10 is provided at the upper end of the tube body 401, and the liquid inlet gap 10 is connected to the liquid accumulation chamber 7 at the upper part of the switch valve 22; an open groove 11 is provided at the lower end of the tube body 401, and the open groove 11 is connected to the lower joint 3; an air intake channel 12 connected to the air storage chamber 9 is provided on the first annular protrusion 5 along the axial direction, and a one-way valve spool 13 is provided in the air intake channel 12, and the one-way valve spool 13 is fixed in the air intake channel 12 by a one-way valve bolt, and a channel is provided on the one-way valve bolt for communicating with the air storage chamber 9.

[0022] In this embodiment, it should be noted that the direction from front to back refers to the flow direction of the fluid in the switch valve 22 .

[0023] In this embodiment, the first annular protrusion 5 is connected to the inner wall of the main body 2 in a sliding and sealing manner, and an annular seal is arranged between the two. The second annular protrusion 6 is connected to the outer wall of the tube body 401 in a sliding and sealing manner, and an annular seal is also arranged between the two. Finally, the first annular protrusion 5, the second annular protrusion 6, the inner wall of the main body 2 and the outer wall of the tube body 401 are enclosed in the cavity of the main body 2 to form the liquid accumulation chamber 7, and the liquid accumulation chamber 7 is located at the upper part of the switch valve.

[0024] In this embodiment, the third annular protrusion 8 is slidingly and sealingly connected to the outer wall of the tube body 401, and an annular seal is arranged therebetween. The first annular protrusion 5, the third annular protrusion 8, the inner wall of the main body 2 and the outer wall of the tube body 401 are enclosed in the cavity of the main body 2 to form the air storage chamber 9, which is located at the lower part of the switch valve.

[0025] As a preferred embodiment, the width of the liquid inlet gap 10 arranged on the tube body 401 is not greater than 0.1 mm, so that when the sand liquid is passed into the switch valve, only the liquid can flow into the liquid accumulation chamber 7 from the liquid inlet gap 10, while the solid matter in the sand liquid is blocked by the gap, which plays a certain filtering role.

[0026] As a preferred embodiment, in order to ensure the sealing performance of the air storage chamber 9 and prevent the gas in the air storage chamber 9 from overflowing outward after the one-way valve core fails, a threaded hole 14 is provided at the air inlet end of the air inlet channel 12, and a sealing bolt is provided in the threaded hole 14, and the sealing bolt realizes secondary sealing of the air storage chamber 9.

[0027] As a preferred embodiment, the piston head 402 is provided with a first conical surface 15, and the inner wall of the lower joint 3 is provided with a second conical surface 16 corresponding to the first conical surface 15. The first conical surface 15 is adapted to the second conical surface 16, and the piston head can better block the liquid outlet of the lower joint 3, thereby improving the effect of sandblasting and perforating.

[0028] As 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 main body 1 and prevent the fluid from flowing directly into the liquid accumulation chamber 7 from the gap therebetween, 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 main body 2, and the lower end of the liquid guide tube 17 is connected to the upper end of the main body 2 by a thread, and a seal is installed at the connection.

[0029] In this embodiment, the one-way valve core 13 is a conventional valve core, and the end face of the valve core fits 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 movement of the valve core back and forth. During the installation process, the valve core should be installed first, and then the one-way valve bolt should be tightened.

[0030] In this embodiment, the installation method of the switch valve 22 is as follows: first, the lower joint 3 is threadedly connected to the body 2; then, the tubular piston 4 is installed in the lower joint 3 and the body 2; then, 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 an inert gas is slowly filled in the air storage chamber 9 of the switch valve. The inert gas can be nitrogen or other gases, and the filling pressure is 5~25Mpa; after the gas filling is completed, finally, the liquid guide tube 4 and the upper joint 5 are installed to complete the assembly of the entire switch valve 22.

[0031] Based on the same inventive concept, an embodiment of the present invention further proposes a working method for sandblasting, perforating, flushing and filling a sand pipe string applicable to a coiled pipe, and the method is specifically as follows: First, lower the process pipe string into the well. The structure of the pipe string is as shown in the attached manual. Figure 4 , including a casing 18 and a continuous oil pipe 19 arranged in the casing 18, the lower end of the continuous oil pipe 19 is connected to a safety joint 20, and the lower end of the safety joint 20 is connected to an injector 21 through a pipeline, the injection hole on the injector 21 is in a normally open state, the injector 21 is aligned with the position that needs to be modified, and the switch valve 22 is connected to the lower end of the injector 21, the liquid inlet and the liquid outlet of the switch valve 22 are in a normally open state, and the gas storage chamber 9 of the switch valve 22 is pre-filled with inert gas, and the pressure of the filled inert gas is generally 12-18Mpa, and the maximum cannot exceed 18Mpa.

[0032] When liquid is injected from the coiled tubing 19, 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 tubular piston 4 through the liquid inlet at the upper end of the switch valve 22. Part of the liquid entering the tubular piston 4 enters the liquid accumulation chamber 7 through the liquid inlet gap 10 at the upper end, thereby pushing the tubular piston 4 to move toward the lower joint 3. Another part of the liquid passes through the fluid channel in the tubular piston 4, flows out to the lower joint 3 through the open groove 11 at the lower end of the tube body 401, and finally enters the annulus of the casing 18 through the liquid outlet on the lower joint 3.

[0033] In this embodiment, the volumes of the liquid accumulating chamber 7 and the gas storage chamber 9 change during the upward and downward movement of the tubular piston 4. For example, when the tubular piston 4 moves downward toward the lower joint 3, the volume of the gas storage chamber 9 gradually decreases, and the volume of the liquid accumulating chamber 7 gradually increases. When the tubular piston 4 moves downward toward the lower joint 3, the gas filled in the gas storage chamber 9 may be compressed to store energy, and the gas pressure in the chamber gradually increases. When the displacement of the liquid flowing into the liquid inlet decreases, the gas in the gas storage chamber 9 releases energy, pushing the tubular piston 4 toward the direction of the upper joint 1.

[0034] When the surface pump pressure is increased to 40-60 MPa and the sand and liquid displacement in the coiled tubing 19 reaches 0.65-0.8 m³ / min, sandblasting and perforating operations will be carried out. The tubular piston 4 is pushed down to the limit position by the sand and liquid. At this time, the piston head 402 completely blocks the liquid outlet on the lower joint 3, and the liquid outlet of the switch valve 22 is sealed; during perforating, the sand and liquid are injected from the coiled tubing 19 and finally ejected from the ejection hole on the ejector 21.

[0035] When the surface pump pressure is lowered to below 25 MPa and the sand liquid in the coiled tubing 19 is reduced to a displacement of 0.5 m³ / min, sand filling operation will be carried out, and the gas in the air storage chamber 9 pushes the tubular piston 4 to move upward in the direction of the upper joint 1, the piston head 402 is out of contact with the liquid outlet of the lower joint 3, and the liquid outlet of the switch valve 22 is opened. During sand filling, the sand liquid is injected from the coiled tubing 19, a part of which enters the annulus of the casing 18 through the injection hole on the injector 21, and a part of which enters the annulus of the casing 18 through the liquid outlet on the lower joint 3.

[0036] In this embodiment, if sand flushing operation is required, well repair fluid or sand flushing fluid is introduced into the coiled tubing 19, and the pump pressure is controlled to be below 25 MPa. The discharge volume of the sand flushing fluid in the coiled tubing 19 is less than 0.5 m³ / min, and then the sand flushing operation can be performed. Similarly, after the sand flushing fluid is injected from the coiled tubing 19, a part of it enters the annulus of the casing 18 through the injection hole on the injector 21, and a part of it enters the annulus of the casing 18 through the liquid outlet on the lower joint 3.

[0037] In this way, through pressure conversion, sand filling and sand flushing operations, we control the pump pressure below 25MPa and the displacement below 0.5m³ / min; during fracturing operations, we increase the surface pump pressure to 40~60Mpa and the displacement reaches 0.65~0.8m³ / min for sandblasting and perforating. This reduces the problem of pulling out the pipe column to replace the sand flushing when the original process pipe column is sand flushed.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention 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 therefore should not be understood as limiting the scope of protection of the present invention.

[0039] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A sandblasting perforating sand filling pipe string suitable for a coiled pipe, comprising a casing (18) and a coiled tubing (19) arranged in the casing (18), wherein the lower end of the coiled tubing (19) is connected to a safety joint (20), an ejector (21) is connected to the lower end of the safety joint (20) via a pipeline, and the lower end of the ejector (21) is connected to the switch valve (22), wherein the switch valve (22) comprises an upper joint (1), a body (2) and a lower joint (3) which are connected in sequence from front to back, and wherein: A tubular piston (4) is slidably and sealingly connected in the internal cavity of the body (2). The tubular piston (4) comprises 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 joint (1). The piston head (402) is arranged at the lower end of the tube body (401). The piston head (402) is matched with the liquid outlet of the lower joint (3). A first annular protrusion (5) is arranged on the outer wall of the tube body (401). A second annular protrusion (6) is arranged on the inner wall of the body (2). The first annular protrusion (5) and the second annular protrusion (6) are matched to each other to form a seal between the outer wall of the tube body (401) and the inner wall of the body (2). A liquid accumulation chamber (7) located at the upper part of the switch valve is formed between the inner wall of the lower joint (3); a third annular protrusion (8) is provided on the inner wall of the lower joint (3); after the third annular protrusion (8) cooperates with the first annular protrusion (5), a closed air storage chamber (9) located at the lower part of the switch valve is formed between the outer wall of the tube body (401) and the inner wall of the main body (2); a liquid inlet gap (10) communicating with the liquid accumulation chamber (7) is provided at the upper end of the tube body (401), and an open groove (11) communicating with the lower joint (3) is provided at the lower end; an air intake channel (12) communicating with the air storage chamber (9) is provided on the first annular protrusion (5), and a one-way valve core (13) is provided in the air intake channel (12).

2. The sandblasting perforation sand filling pipe string suitable for coiled pipe according to claim 1, characterized in that: The air intake end of the air intake passage (12) is provided with a threaded hole (14), and a sealing bolt is provided in the threaded hole (14).

3. The sandblasting perforation sand filling pipe string suitable for coiled pipe 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 joint (3) is provided with a second conical surface (16) corresponding to the first conical surface (15).

4. The sandblasting perforation sand filling pipe string suitable for coiled tubing according to claim 1, characterized in that: The width of the liquid inlet gap (10) is less than 0.1 mm.

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

6. The working method of sandblasting perforating and sand filling pipe string applicable to coiled pipe according to claim 1, characterized in that: The pipe string is lowered into the well, and the injector (21) is aligned with the position to be modified; the injection hole on the injector (21) is in a normally open state, the liquid inlet and the liquid outlet of the switch valve (22) are in a normally open state, and the gas storage chamber (9) of the switch valve (22) is filled with an inert gas; When the oil pipe carries sand liquid, part of the liquid enters the annulus of the casing (18) through the injection hole on the injector (21), part of the liquid enters the tubular piston (4) through the liquid inlet at the upper end of the switch valve (22), part of the liquid entering the tubular piston (4) enters the liquid accumulation chamber (7) through the liquid inlet gap (10) at the upper end, pushing the tubular piston (4) to move toward the lower joint (3), and another part of the liquid passes through the fluid channel in the tubular piston (4), flows out to the lower joint (3) through the open groove (11) at the lower end of the tube body (401), and finally enters the annulus of the casing (18) through the liquid outlet on the lower joint (3); The surface pump pressure and the liquid displacement in the coiled tubing (19) are increased to perform sandblasting and perforating. The tubular piston (4) moves downward to the limit position, and the piston head (402) blocks the liquid outlet on the lower joint (3). During perforating, sand liquid is injected from the coiled tubing (19) and ejected from the ejection hole on the ejector (21); The surface pump pressure and the liquid displacement in the coiled tubing (19) are reduced to perform sand filling operation. The gas in the gas storage chamber (9) pushes the tubular piston (4) upward, and the liquid outlet on the lower joint (3) is opened. During sand filling, sand liquid is injected from the coiled tubing (19), a part of which enters the annulus of the casing (18) through the injection hole on the injector (21), and a part of which enters the annulus of the casing (18) through the liquid outlet on the lower joint (3); The surface pump pressure and the liquid displacement in the coiled tubing (19) are reduced to perform sand flushing operations. Sand flushing liquid is injected 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 joint (3).

7. A method for sandblasting, perforating and filling a sand pipe string for a coiled pipe according to claim 6, characterized in that: When the surface pump pressure increases to 40-60 MPa and the liquid displacement in the coiled tubing (19) reaches 0.65-0.8 m3 / min, sandblasting and perforating are performed.

8. The working method of sandblasting perforating and sand filling pipe string applicable to coiled tubing according to claim 6, characterized in that: When the surface pump pressure drops below 25 MPa and the liquid displacement in the coiled tubing (19) drops to 0.5 m3 / min, sand filling or sand flushing operations are performed.

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