Concentric soft and hard combination coiled tubing acidizing and chemical sand control device and method of use

Abstract

The present application relates to the technical field of petroleum engineering, and particularly relates to a concentric soft and hard combined coiled tubing acidification and chemical sand control device and a use method thereof. The technical scheme is as follows: the upper part of a flow connection head is connected with a concentric soft and hard combined coiled tubing composed of a continuous low-carbon alloy steel pipe and a continuous rubber pipe, and a ground pressing connector is connected to the top of the concentric soft and hard combined coiled tubing; the lower end of a well flushing connector is connected with a lower connector through a connecting pressure cap, the upper end of the well flushing connector is connected with the continuous low-carbon alloy steel pipe on the outside and connected with the continuous rubber pipe on the inside. When the acidification agent or the chemical sand consolidation agent is injected through the continuous rubber pipe, the continuous rubber pipe is deformed outwardly under pressure and leans against the inner wall of the continuous low-carbon alloy steel pipe, so that the liquid passing capacity is improved, and the flow capacity of the flow restrictor and the injection capacity to the formation are also improved; in addition, when the well flushing fluid is injected through the annulus, the function of rapid well flushing is realized, and the problem that the well flushing channel cannot be realized due to the well flushing fluid entering the formation during the well flushing process is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum engineering, in particular to a concentric soft and hard combined coiled tubing acidification and chemical sand control device and a use method thereof. BACKGROUND

[0002] In the process of oil development, acidification and chemical sand control are two common processes. The original process includes injection process and well flushing process. In the injection process, K344 packers are used for sealing, and then acidizing agents or chemical sand stabilizing agents are injected downward through the coiled tubing, and then the downhole throttles are used to inject the agents into the target oil layer to achieve acidification or chemical sand control. In the well flushing process, flushing fluid is injected into the annulus between the casing and the coiled tubing, and the K344 packers should be in the unblocking state at this time. The flushing fluid will flush out the acidizing agents or chemical sand stabilizing agents stored in the coiled tubing, and then the pipe string will be pulled out. However, due to the complexity of the well, accidents often occur, such as high pressure at the bottom of the well. After the upper K344 packer is pressed open by the flushing fluid, the flushing fluid enters the formation, causing the lower K344 packer to be unable to unblock. Thus, the flushing channel cannot be formed, and the flushing purpose cannot be achieved. Moreover, the entire pipe string cannot be pulled out, resulting in a major repair operation. That is, the existing technology has the following problems: the process of injecting acidizing agents or chemical sand stabilizing agents generally has no problems, but the well flushing process often has problems, such as the flushing fluid entering the formation and the flushing channel being unable to be formed, resulting in the failure to complete the well flushing.

[0003] In addition, the existing coiled tubing is generally made of low-carbon alloy steel pipe material, which has good flexibility and is also called flexible tubing. A coiled tubing is several kilometers long and can replace conventional tubing to perform many operations. The coiled tubing operation equipment has the characteristics of pressure operation and continuous pulling. The equipment has small size, fast operation cycle and low cost. However, the existing coiled tubing does not have a concentric double tube structure. Since a coiled tubing is several kilometers long, it is impossible to realize the winding of the concentric double tube. In particular, if two concentric low-carbon alloy steel pipes are made, it is difficult to maintain a uniform annulus when winding a roll. Moreover, the second problem is that if the conventional concentric double-layer tubing is connected in sequence through the joints, the inner diameter of the inner tube is fixed, which limits the liquid passage cross section and reduces the liquid passage capacity. Moreover, the construction difficulty and cost of connecting in sequence through the joints are very high. SUMMARY

[0004] The present application aims at the above-mentioned defects in the prior art, and provides a concentric soft and hard combined coiled tubing acidification and chemical sand control device and a use method.

[0005] The concentric soft and hard combined coiled tubing acidification and chemical sand control device provided by the present application has the technical scheme that: it comprises a blind plug, a lower packer, an injection flow restrictor, an upper packer, the injection flow restrictor is located between the lower packer and the upper packer, and a blind plug is installed at the bottom, wherein, it further comprises a flow-through connector, a continuous low-carbon alloy steel pipe, a continuous rubber pipe and a ground pressing connector, the upper part of the flow-through connector is connected with the concentric soft and hard combined coiled tubing composed of the continuous low-carbon alloy steel pipe and the continuous rubber pipe, and the top of the concentric soft and hard combined coiled tubing is connected with the ground pressing connector; the flow-through connector comprises a well flushing connector, a connecting pressure cap and a lower connector, the lower end of the well flushing connector is connected with the lower connector through the connecting pressure cap, the upper end of the well flushing connector is connected with the continuous low-carbon alloy steel pipe on the outside and connected with the continuous rubber pipe on the inside.

[0006] Preferably, the well flushing connector comprises a connector body, a setting tool, a plug, a spring, a spring seat and a base, a plurality of communication holes are arranged on the outer wall of the connector body, a one-way valve composed of the plug, the spring and the spring seat is arranged in each communication hole, the top of the connector body is connected with the continuous low-carbon alloy steel pipe, the lower side of the continuous low-carbon alloy steel pipe is installed with the setting tool, the upper end of the plug is connected with the setting tool in a matched mode, and the inner wall of the connector body is connected with the lower end of the continuous rubber pipe.

[0007] Preferably, the spring seat is of a hollow structure in the middle, and the base is provided with a through hole, so that the well flushing fluid can enter the inner cavity of the flow-through connector after the plug and the spring are opened.

[0008] Preferably, the lower side of the outer wall of the well flushing connector is provided with a protruding part, the middle part of the outer wall of the lower connector is provided with a protruding connecting part, and the protruding connecting part is provided with an external thread on the outside, the upper part of the connecting pressure cap is pressed against the protruding part of the well flushing connector, and the lower part is connected with the protruding connecting part of the lower connector in a threaded mode.

[0009] Preferably, the lower end of the surface pressure joint is connected to the upper end of the continuous low-carbon alloy steel pipe through threading, the inner cavity of the surface pressure joint is connected to the upper end of the continuous rubber pipe through the rubber pipe extrusion fixing head, and a well flushing external joint is installed on the outer wall of the surface pressure joint, which is communicated with the annulus between the continuous low-carbon alloy steel pipe and the continuous rubber pipe through a connecting channel.

[0010] Preferably, the injection throttle comprises an injector upper joint, a sealing piston ring, a return spring, a pressure adjusting cap, a central pipe, and a liquid injection port, the upper end of the central pipe is provided with the injector upper joint, the upper end of the injector upper joint is provided with an internal thread, the lower end is provided with an external expansion cover, the central pipe on the inner side of the external expansion cover is provided with the liquid injection port, the sealing piston ring is installed at the annulus between the external expansion cover and the central pipe, the lower end of the sealing piston ring is connected to the pressure adjusting cap through the return spring, the pressure adjusting cap is connected to the central pipe through threading, and the tightness of the return spring is adjusted through the pressure adjusting cap, so as to further adjust the opening pressure of the sealing piston ring.

[0011] Preferably, the lower packer and the upper packer adopt K344 packers, the K344 packer comprises a packer upper joint, an expansion rubber sleeve, a packer central pipe, and a packer lower joint, one end of the packer central pipe is provided with the packer upper joint, the other end is provided with the packer lower joint, the expansion rubber sleeve is installed in the middle of the packer central pipe, and a liquid passage is arranged on the packer central pipe; part of the liquid in the packer central pipe enters the annulus between the expansion rubber sleeve and the packer central pipe through the liquid passage, so as to push the expansion rubber sleeve to expand to the inner wall of the casing under the well to realize the sealing effect.

[0012] Preferably, the K344 packer further comprises a rubber sleeve embedded part, the rubber sleeve embedded part is arranged at both ends of the expansion rubber sleeve, the upper end of the expansion rubber sleeve is connected to the lower end of the packer upper joint through the rubber sleeve embedded part, and the lower end of the expansion rubber sleeve is connected to the upper end of the packer lower joint through the rubber sleeve embedded part.

[0013] The use method of the concentric soft and hard combined coiled tubing acidification and chemical sand control device mentioned in the application is as follows:

[0014] I. Assembling the concentric soft and hard combined coiled tubing acidification and chemical sand control device:

[0015] Firstly, the continuous rubber pipe is passed into the inner cavity of the continuous low-carbon alloy steel pipe and connected to the flow-through connector, the upper end of the well flushing connector is connected to the continuous low-carbon alloy steel pipe on the outside and connected to the continuous rubber pipe on the inside; then, the upper packer, the injection throttle and the lower packer are sequentially connected to the flow-through connector through a single-layer oil pipe, and a blind plug is installed at the bottom to form the concentric soft and hard combined coiled tubing acidification and chemical sand control device; finally, the casing under the well is lowered and reaches the designed position.

[0016] II. When injecting acidizing agent or chemical sand consolidating agent:

[0017] When injecting acidizing agent into the inner cavity of the surface pressure joint at the surface wellhead to acidize the formation, the acidizing agent enters the flow-through connector downward along the continuous rubber pipe. Since the flow-through connector is provided with a spring and a plug to form a one-way valve, the acidizing agent can only continue to flow downward along the single-layer oil pipe to the injection choke. Since the opening pressure of the injection choke is less than the opening pressure of the upper and lower packers, the expansion rubber of the upper and lower packers is inflated and sealed with the inner wall of the casing. Then, the injection choke is opened, the acidizing agent pushes open the sealing piston ring of the choke, sprays along the injection port, and then is injected into the target oil layer between the upper and lower packers to realize the acidizing process. When injecting chemical sand consolidating agent, the process is the same as the above acidizing process.

[0018] III. After injecting acidizing agent or chemical sand consolidating agent, when washing well:

[0019] When injecting washing fluid into the washing external joint on one side of the surface pressure joint at the surface wellhead, the washing fluid flows downward along the annulus between the continuous low-carbon alloy steel pipe and the continuous rubber pipe until the washing fluid reaches the flow-through connector. When the pressure of the washing fluid is greater than the spring force of the spring below the plug, the plug is opened, the washing fluid enters the inner cavity of the flow-through connector, and then flows upward in the reverse direction along the inner cavity of the continuous rubber pipe. Under the combined pressure of the washing fluid and the mixture of acidizing agent or chemical sand consolidating agent washed out, the continuous rubber pipe expands and the internal pressure between the continuous low-carbon alloy steel pipe and the continuous rubber pipe reaches equilibrium. Until the acidizing agent or chemical sand consolidating agent in the inner cavity of the continuous rubber pipe and the inner cavity of the single-layer oil pipe below the flow-through connector is sent to the surface wellhead under the negative pressure of the washing fluid, the washing process is completed.

[0020] Compared with the prior art, the beneficial effects of the present application are as follows:

[0021] The application overcomes the defects of the prior art by using the soft and hard combined continuous tubing composed of concentric continuous rubber pipe and continuous low-carbon alloy steel pipe. When the acidizing agent or chemical sand consolidating agent is injected through the inner layer continuous rubber pipe, the continuous rubber pipe is deformed outwardly under pressure and leans against the inner wall of the continuous low-carbon alloy steel pipe, thereby improving the drift diameter and pressure resistance of the double-layer continuous tubing, improving the liquid passing capacity of the inner layer pipe of the continuous tubing, and improving the flow capacity of the flow restrictor and the injection capacity to the formation. In addition, during the well flushing process, the well flushing fluid is injected through the annulus between the continuous rubber pipe and the continuous low-carbon alloy steel pipe. At the initial stage of injection, the continuous rubber pipe is compressed and deformed towards the center, the well flushing fluid enters the continuous rubber pipe in the reverse direction through the flow connection head, and then the continuous rubber pipe expands again and forms a balanced state. The well flushing fluid carrying the downhole acidizing agent or chemical sand consolidating agent returns to the ground along the continuous rubber pipe, and the well flushing is completed, avoiding the problem that the well flushing fluid enters the annulus between the casing and the continuous tubing and then possibly enters the formation, resulting in the failure of forming the well flushing channel and the failure of well flushing. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the overall structure schematic diagram of the application during construction;

[0023] Figure 2 is the structure schematic diagram of the flow connection head of the application;

[0024] Figure 3 is the structure schematic diagram of the ground pressure joint;

[0025] Figure 4 is the structure schematic diagram of the rubber pipe extrusion fixing head;

[0026] Figure 5 is the structure schematic diagram of the injection flow restrictor;

[0027] Figure 6 is the structure schematic diagram of the upper packer;

[0028] Figure 7 is the schematic diagram of the application when injecting acidizing agent or chemical sand consolidating agent;

[0029] Figure 8 is the schematic diagram of the application when flushing the well;

[0030] Blind plug 1, lower packer 2, injection flow restrictor 3, upper packer 4, flow-through connector 5, continuous low-carbon alloy steel pipe 6, continuous rubber pipe 7, ground pressing connector 8, well flushing external connector 9, oil layer 10, casing 11, rubber pipe extrusion fixing head 12, injection device upper connector 3.1, internal thread 3.1.1, external expansion cover 3.1.2, sealing piston ring 3.2, return spring 3.3, pressure adjustment cap 3.4, central pipe 3.5, injection port 3.6, packer upper connector 4.1, rubber sleeve embedded part 4.2, expansion rubber sleeve 4.3, packer central pipe 4.4, packer lower connector 4.5, liquid passage hole 4.6, well flushing connector 5.1, connecting pressure cap 5.2, lower connector 5.3, protruding part 5.1.1, connector body 5.1.2, setting tool 5.1.3, plug 5.1.4, spring 5.1.5, spring seat 5.1.6, base 5.1.7, protruding connecting part 5.3.1, connecting channel 8.1, rubber pipe fixing groove 12.1, fixing head external thread 12.2. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, which should be understood as merely illustrative and explanatory, and not limiting the present application.

[0032] Reference Figures 1-3 The present application refers to a concentric soft and hard combined coiled tubing acidification and chemical sand control device, and the technical scheme is as follows: a blind plug 1, a lower packer 2, an injection flow restrictor 3, and an upper packer 4 are included, the injection flow restrictor 3 is located between the lower packer 2 and the upper packer 4, and a blind plug 1 is installed at the bottom, wherein, a flow-through connector 5, a continuous low-carbon alloy steel pipe 6, a continuous rubber pipe 7, and a ground pressing connector 8 are further included, the upper part of the flow-through connector 5 is connected with the continuous low-carbon alloy steel pipe 6 and the continuous rubber pipe 7 to form a concentric soft and hard combined coiled tubing, and the top of the concentric soft and hard combined coiled tubing is connected with the ground pressing connector 8; the flow-through connector 5 includes a well flushing connector 5.1, a connecting pressure cap 5.2, and a lower connector 5.3, the lower end of the well flushing connector 5.1 is connected with the lower connector 5.3 through the connecting pressure cap 5.2, the upper end of the well flushing connector 5.1 is connected with the continuous low-carbon alloy steel pipe 6 on the outside and connected with the continuous rubber pipe 7 on the inside.

[0033] Reference Figure 2The well flushing connector 5.1 mentioned in the application comprises a connector body 5.1.2, a setting tool 5.1.3, a plug 5.1.4, a spring 5.1.5, a spring seat 5.1.6 and a base 5.1.7, a plurality of communication holes are arranged on the outer wall of the connector body 5.1.2, a one-way valve composed of the plug 5.1.4, the spring 5.1.5 and the spring seat 5.1.6 is arranged in each communication hole, the top of the connector body 5.1.2 is connected with a continuous low-carbon alloy steel pipe 6, the lower side of the continuous low-carbon alloy steel pipe 6 is provided with the setting tool 5.1.3, the upper end of the plug 5.1.4 is connected with the setting tool 5.1.3 in a matched mode, and the inner wall of the connector body 5.1.2 is connected with the lower end of a continuous rubber pipe 7.

[0034] The spring seat 5.1.6 is hollow in the middle, and the base 5.1.7 is provided with a through hole, so that the well flushing fluid can enter the inner cavity of the flow connector 5 after the plug 5.1.4 and the spring 5.1.5 are opened.

[0035] In addition, the lower side of the outer wall of the well flushing connector 5.1 is provided with a protruding part 5.1.1, the middle part of the outer wall of the lower connector 5.3 is provided with a protruding connecting part 5.3.1, the outer wall of the protruding connecting part 5.3.1 is provided with external threads, the protruding part 5.1.1 of the well flushing connector 5.1 is pressed by the upper part of the pressure cap 5.2, and the lower part is connected with the protruding connecting part 5.3.1 of the lower connector 5.3 through threads.

[0036] Referring to Figure 3 and Figure 4 The lower end of the ground pressure connector 8 is connected with the upper end of the continuous low-carbon alloy steel pipe 6 through threads, the inner cavity of the ground pressure connector 8 is connected with the upper end of the continuous rubber pipe 7 through the rubber pipe extrusion fixing head 12, the well flushing outer connector 9 is arranged on the outer wall of the ground pressure connector 8, and the well flushing outer connector 9 is connected with the annulus between the continuous low-carbon alloy steel pipe 6 and the continuous rubber pipe 7 through the connecting channel 8.1.

[0037] The upper part of the rubber pipe extrusion fixing head 12 is provided with a fixing head external thread 12.2, and the lower part of the rubber pipe extrusion fixing head 12 is provided with a rubber pipe fixing groove 12.1.

[0038] Referring to Figure 5The injection throttle 3 comprises an injector upper joint 3.1, a sealing piston ring 3.2, a return spring 3.3, a pressure adjusting cap 3.4, a central pipe 3.5, and a liquid injection port 3.6.

[0039] Referring to Figure 6 The lower packer 2 and the upper packer 4 comprise K344 packers, which comprise a packer upper joint 4.1, an expansion rubber sleeve 4.3, a packer central pipe 4.4, and a packer lower joint 4.5.

[0040] The K344 packer further comprises rubber sleeve pre-embedded parts 4.2, which are arranged at two ends of the expansion rubber sleeve 4.3.

[0041] The technical scheme of the use method of the concentric soft and hard combined coiled tubing acidification and chemical sand control device is as follows:

[0042] I. Assembling the concentric soft and hard combined coiled tubing acidification and chemical sand control device

[0043] First, the continuous rubber tube 7 is passed into the inner cavity of the continuous low-carbon alloy steel tube 6 and connected to the flow-through connector 5, the upper end of the well flushing connector 5.1 is connected to the outside of the continuous low-carbon alloy steel tube 6, and the inside is connected to the continuous rubber tube 7; then, the upper packer 4, the injection throttle 3 and the lower packer 2 are sequentially connected in order through the single-layer oil pipe at the lower end of the flow-through connector 5, and the blind plug 1 is installed at the bottom to form the concentric soft and hard combined continuous oil pipe acidizing and chemical sand control device; finally, the downhole casing 11 is lowered and reaches the designed position;

[0044] II. When injecting acidizing agent or chemical sand consolidation agent:

[0045] Referring to Figure 7 When the acidizing agent is injected into the inner cavity of the surface pressure joint 8 at the surface wellhead, the acidizing agent enters the flow-through connector 5 along the continuous rubber tube 7, and due to the one-way valve formed by the spring 5.1.5 and the plug 5.1.4 in the flow-through connector 5, the acidizing agent can only continue to flow downward along the single-layer oil pipe to the injection throttle 3, and since the opening pressure of the injection throttle 3 is less than that of the upper packer 4 and the lower packer 2, the expansion rubber of the upper packer 4 and the lower packer 2 is inflated and sealed with the inner wall of the casing 11; then, the injection throttle 3 is opened, the acidizing agent pushes open the sealing piston ring 3.2 of the throttle 3, sprays out along the injection port 3.6, and then is injected into the target oil layer 10 between the upper packer 4 and the lower packer 2, realizing the acidizing process; when injecting the chemical sand consolidation agent, the process is the same as the above acidizing process;

[0046] III. After injecting the acidizing agent or the chemical sand consolidation agent, when the well needs to be flushed:

[0047] Referring to Figure 8 When the well flushing fluid is injected into the well flushing external joint 9 on one side of the surface pressure joint 8 at the surface wellhead, the well flushing fluid flows downward along the annulus between the continuous low-carbon alloy steel tube 6 and the continuous rubber tube 7, until the well flushing fluid reaches the flow-through connector 5, when the pressure of the well flushing fluid is greater than the spring force of the spring 5.1.5 under the plug 5.1.4, the plug 5.1.4 is opened, the well flushing fluid enters the inner cavity of the flow-through connector 5, and then flows upward in the reverse direction along the inner cavity of the continuous rubber tube 7, under the combined pressure of the well flushing fluid and the mixture of the acidizing agent or the chemical sand consolidation agent washed out, the continuous rubber tube 7 expands, and the internal pressure between the continuous low-carbon alloy steel tube 6 and the continuous rubber tube 7 reaches balance, until the acidizing agent or the chemical sand consolidation agent in the inner cavity of the continuous rubber tube 7 and the single-layer oil pipe below the flow-through connector 5 is sent out to the surface wellhead under the negative pressure of the well flushing fluid, thus completing the well flushing process.

[0048] The above merely describes some preferred embodiments of the present application, and any skilled person in the art can modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modifications or equivalent transformations according to the technical solutions of the present application are within the scope of the present application.

Claims

1. A concentric soft and hard combination coiled tubing acidification and chemical sand control device, comprising a blind plug (1), a lower packer (2), an injection throttle (3), an upper packer (4), the injection throttle (3) being located between the lower packer (2) and the upper packer (4), and the bottom being provided with the blind plug (1), characterized in that: Also include the flow connection (5), continuous low carbon alloy steel pipe (6), continuous rubber pipe (7), ground pressure connector (8), the upper part of the flow connection (5) is connected with the continuous low carbon alloy steel pipe (6) and the continuous rubber pipe (7) to form a concentric soft and hard combination coiled tubing, and the ground pressure connector (8) is connected at the top of the concentric soft and hard combination coiled tubing; the flow connection (5) includes a well flushing connector (5.1), a connecting pressure cap (5.2) and a lower connector (5.3), the lower end of the well flushing connector (5.1) is connected with the lower connector (5.3) through the connecting pressure cap (5.2), the upper end of the well flushing connector (5.1) is connected with the continuous low carbon alloy steel pipe (6) on the outside and connected with the continuous rubber pipe (7) on the inside; ​ the well flushing connector (5.1) includes a connector body (5.1.2), a setting tool (5.1.3), a plug (5.1.4), a spring (5.1.5), a spring seat (5.1.6) and a base (5.1.7), a plurality of communication holes are formed on the outer wall of the connector body (5.1.2), a one-way valve composed of the plug (5.1.4), the spring (5.1.5) and the spring seat (5.1.6) is installed in each communication hole, the top of the connector body (5.1.2) is connected with the continuous low carbon alloy steel pipe (6), the lower side of the continuous low carbon alloy steel pipe (6) is installed with the setting tool (5.1.3), the upper end of the plug (5.1.4) is connected with the setting tool (5.1.3), the inner wall of the connector body (5.1.2) is connected with the lower end of the continuous rubber pipe (7); the spring seat (5.1.6) is hollow in the middle, and the base (5.1.7) is provided with a through hole, so that the well flushing fluid can enter the inner cavity of the flow connection (5) after the plug (5.1.4) and the spring (5.1.5) are opened. the lower side of the outer wall of the well flushing connector (5.1) is provided with a protruding part (5.1.1), the middle part of the outer wall of the lower connector (5.3) is provided with a protruding connecting part (5.3.1), and the protruding connecting part (5.3.1) is provided with external threads, the protruding part (5.1.1) of the well flushing connector (5.1) is pressed by the upper part of the connecting pressure cap (5.2), and the lower part of the connecting pressure cap (5.2) is connected with the protruding connecting part (5.3.1) of the lower connector (5.3) through threads.

2. The concentric composite coiled tubing acidizing and chemical sand control device of claim 1, wherein: the lower end of the ground pressure connector (8) is connected with the upper end of the continuous low carbon alloy steel pipe (6) through threads, the inner cavity of the ground pressure connector (8) is connected with the upper end of the continuous rubber pipe (7) through a rubber pipe extrusion fixing head (12), and a well flushing external connector (9) is installed on the outer wall of the ground pressure connector (8), the well flushing external connector (9) is connected with the annulus between the continuous low carbon alloy steel pipe (6) and the continuous rubber pipe (7) through a connecting channel (8.1). ​ 3. The concentric composite coiled tubing acidizing and chemical sand control device of claim 2, wherein: ​ 4. The concentric composite coiled tubing acidizing and chemical sand control device of claim 3, wherein: The injection throttle (3) comprises an injector upper joint (3.1), a sealing piston ring (3.2), a return spring (3.3), a pressure adjusting cap (3.4), a central tube (3.5), and a liquid injection port (3.6). The upper end of the central tube (3.5) is provided with the injector upper joint (3.1). The upper end of the injector upper joint (3.1) is provided with an internal thread (3.1.1), and the lower end is provided with an external expansion cover (3.1.2). The central tube (3.5) on the inner side of the external expansion cover (3.1.2) is provided with the liquid injection port (3.6). The annular space between the external expansion cover (3.1.2) and the central tube (3.5) is provided with the sealing piston ring (3.2). The lower end of the sealing piston ring (3.2) is connected to the pressure adjusting cap (3.4) through the return spring (3.3). The pressure adjusting cap (3.4) is connected to the central tube (3.5) through a thread. The tightness of the return spring (3.3) is adjusted through the pressure adjusting cap (3.4), and then the opening pressure of the sealing piston ring (3.2) is adjusted.

5. The concentric composite coiled tubing acidizing and chemical sand control device of claim 4, wherein: The lower packer (2) and the upper packer (4) adopt K344 packers. The K344 packer comprises a packer upper joint (4.1), an expansion rubber sleeve (4.3), a packer central tube (4.4), and a packer lower joint (4.5). One end of the packer central tube (4.4) is provided with the packer upper joint (4.1), and the other end is provided with the packer lower joint (4.5). The expansion rubber sleeve (4.3) is installed in the middle of the packer central tube (4.4). The packer central tube (4.4) is provided with a liquid passage hole (4.6). Part of the liquid in the packer central tube (4.4) enters the annular space between the expansion rubber sleeve (4.3) and the packer central tube (4.4) through the liquid passage hole (4.6), thereby pushing the expansion rubber sleeve (4.3) to expand into the inner wall of the downhole casing (11) to achieve the sealing effect.

6. The concentric composite coiled tubing acidizing and chemical sand control device of claim 5, wherein: The K344 packer further comprises a rubber sleeve embedded part (4.2). The expansion rubber sleeve (4.3) is provided with the rubber sleeve embedded part (4.2) at both ends. The upper end of the expansion rubber sleeve (4.3) is connected to the lower end of the packer upper joint (4.1) through the rubber sleeve embedded part (4.2). The lower end of the expansion rubber sleeve (4.3) is connected to the upper end of the packer lower joint (4.5) through the rubber sleeve embedded part (4.2).

7. The method of using a concentric composite coiled tubing acidizing and chemical sand control device of claim 6, wherein: The process comprises the following steps: I. Assembling the concentric soft and hard combined coiled tubing acidification and chemical sand control device: First, the continuous rubber pipe (7) is passed into the inner cavity of the continuous low-carbon alloy steel pipe (6) and connected to the flow connector (5). The upper end of the well flushing connector (5.1) is connected to the continuous low-carbon alloy steel pipe (6) on the outside and connected to the continuous rubber pipe (7) on the inside. Then, the upper packer (4), the injection throttle (3), and the lower packer (2) are sequentially connected to the flow connector (5) through a single-layer oil pipe at the lower end of the flow connector (5), and a blind plug (1) is installed at the bottom to form the concentric soft and hard combined coiled tubing acidification and chemical sand control device. Finally, the downhole casing (11) is lowered into the well and reaches the designed position. II. When injecting acidizing agent or chemical sand consolidation agent: When the acidizing agent is injected into the inner cavity of the ground pressure connector (8) at the ground wellhead to acidize the formation, the acidizing agent enters the flow-through connector (5) along the continuous rubber pipe (7). Since the flow-through connector (5) is provided with a one-way valve formed by the spring (5.1.5) and the plug (5.1.4) therein, the acidizing agent can only continue to flow downward along the single-layer oil pipe to the injection throttle (3). Since the opening pressure of the injection throttle (3) is less than the opening pressure of the upper packer (4) and the lower packer (2), the expansion rubber tube (4.3) of the upper packer (4) and the lower packer (2) is inflated and realizes the sealing effect with the inner wall of the casing (11). Then, the injection throttle (3) is opened, the acidizing agent pushes open the sealing piston ring (3.2) of the throttle (3), sprays along the injection liquid inlet (3.6), and then is injected into the target oil layer (10) between the upper packer (4) and the lower packer (2) to realize the acidizing process. When the chemical sand stabilizer is injected, the process is the same as the above acidizing process. III. After the acidizing agent or the chemical sand stabilizer is injected, the well needs to be washed: When the well washing fluid is injected into the well washing external connector (9) on one side of the ground pressure connector (8) at the ground wellhead, the well washing fluid flows downward along the annulus between the continuous low-carbon alloy steel pipe (6) and the continuous rubber pipe (7) until the well washing fluid reaches the flow-through connector (5). When the pressure of the well washing fluid is greater than the spring force of the spring (5.1.5) under the plug (5.1.4), the plug (5.1.4) is opened, the well washing fluid enters the inner cavity of the flow-through connector (5), and then flows reversely upward along the inner cavity of the continuous rubber pipe (7). Under the combined pressure of the well washing fluid and the mixture of the acidizing agent or the chemical sand stabilizer washed out, the continuous rubber pipe (7) expands, and the internal pressure between the continuous low-carbon alloy steel pipe (6) and the continuous rubber pipe (7) reaches equilibrium. The acidizing agent or the chemical sand stabilizer in the inner cavity of the continuous rubber pipe (7) and the inner cavity of the single-layer oil pipe below the flow-through connector (5) is sent to the ground wellhead under the negative pressure of the well washing fluid, thereby completing the well washing process.

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