Concentric soft and hard combined coiled tubing acidification and chemical sand prevention device and use method

Abstract

The invention relates to the technical field of petroleum engineering, in particular to a concentric soft and hard combined coiled tubing acidification and chemical sand prevention device and a using method. According to the technical scheme, the upper portion of an overflowing connector is connected with a concentric soft and hard combined continuous oil pipe composed of a continuous low-carbon alloy steel pipe and a continuous rubber pipe, and the top of the concentric soft and hard combined continuous oil pipe is connected with a ground pressing connector; the outer side of the upper end of the well washing connector is connected with a continuous low-carbon alloy steel pipe, and the inner side of the upper end of the well washing connector is connected with a continuous rubber pipe. When an acidifying agent or a chemical sand consolidation agent is injected through the continuous rubber pipe, the continuous rubber pipe is pressed to deform towards the outer side and lean against the inner wall of the continuous low-carbon alloy steel pipe, so that the liquid passing capacity is improved, and the through-flow capacity of the throttler and the capacity of injecting the acidifying agent or the chemical sand consolidation agent into the stratum are also improved; in addition, when the well washing fluid is injected through the annulus, the function of rapid well washing is achieved, and the problem that in the well washing process, the well washing fluid enters the stratum, and consequently a well washing channel cannot be achieved is solved.

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 above-mentioned ground pressure joint is connected with the upper end of the continuous low-carbon alloy steel pipe through threading, the inner cavity of the ground pressure joint is connected with the upper end of the continuous rubber pipe through the rubber pipe extrusion fixing head, and a well flushing external connector is installed on the outer wall of the ground 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 above-mentioned injection throttler comprises an injector upper connector, 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 connector, the upper end of the injector upper connector 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 with the pressure adjusting cap through the return spring, the pressure adjusting cap is connected with 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 above-mentioned lower packer and upper packer adopt K344 packers, the K344 packer comprises a packer upper connector, an expansion rubber sleeve, a packer central pipe, and a packer lower connector, one end of the packer central pipe is provided with the packer upper connector, the other end is provided with the packer lower connector, 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 above-mentioned 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 with the lower end of the packer upper connector through the rubber sleeve embedded part, and the lower end of the expansion rubber sleeve is connected with the upper end of the packer lower connector 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: I. Assembling the concentric soft and hard combined coiled tubing acidification and chemical sand control device: 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 with the continuous low-carbon alloy steel pipe on the outside and connected with the continuous rubber pipe on the inside; then, the upper packer, the injection throttler and the lower packer are sequentially connected to the flow-through connector through a single-layer oil pipe, and the 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. II. When injecting acidification agent or chemical sand consolidation agent: When the acidizing agent is injected into the inner cavity of the ground pressure connector at the ground wellhead to acidize the formation, the acidizing agent enters the flow connector along the continuous rubber pipe, and due to the one-way valve formed by the spring and the plug in the flow connector, the acidizing agent can only continue to flow downward along the single-layer oil pipe to the injection choke, and since the opening pressure of the injection choke is less than that 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, and is sprayed along the injection liquid outlet, and then is injected into the target oil layer between the upper and lower packers to realize the acidizing process; the process of injecting chemical sand consolidation agent is the same as the above acidizing process. III. After injecting the acidizing agent or the chemical sand consolidation agent, the well needs to be washed: When the well is washed, the washing fluid is injected into the washing external connector on one side of the ground pressure connector at the ground wellhead, and 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 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 connector, and then flows reversely upward along the inner cavity of the continuous rubber pipe; under the combined pressure of the washing fluid and the mixture of the washed acidizing agent or chemical sand consolidation agent, the continuous rubber pipe expands and the internal pressure of the annulus between the continuous low-carbon alloy steel pipe and the continuous rubber pipe reaches balance, and the acidizing agent or chemical sand consolidation agent in the inner cavity of the continuous rubber pipe and the inner cavity of the single-layer oil pipe below the flow connector is sent to the ground wellhead under the negative pressure of the washing fluid, thereby completing the washing process.

[0014] Compared with the prior art, the beneficial effects of the present application are as follows: The soft and hard combined continuous oil pipe composed of the concentric continuous rubber pipe and the continuous low-carbon alloy steel pipe can overcome the drawbacks of the prior art; when the acidizing agent or the chemical sand consolidation agent is injected through the inner layer of the continuous rubber pipe, the continuous rubber pipe deforms outwardly and leans against the inner wall of the continuous low-carbon alloy steel pipe under pressure, thereby improving the drift diameter and pressure resistance of the double-layer continuous oil pipe, the liquid passing capacity of the inner layer of the continuous oil pipe, the flow capacity of the choke, and the injection capacity to the formation; in addition, in the washing process, the washing fluid is injected through the annulus between the continuous rubber pipe and the continuous low-carbon alloy steel pipe, the continuous rubber pipe is compressed and deformed towards the center at the beginning of injection, the washing fluid reversely enters the continuous rubber pipe upward through the flow connector, and then the continuous rubber pipe expands again and forms a balanced state; the washing fluid returns to the ground along the continuous rubber pipe with the acidizing agent or the chemical sand consolidation agent under the well, thereby avoiding the problems that the washing fluid enters the annulus between the casing and the connected oil pipe, and then possibly enters the formation, resulting in the failure to form a washing channel and the failure of washing. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1is the schematic diagram of the whole structure during construction of the present application; Figure 2 is the schematic diagram of the structure of the flow connector of the present application; Figure 3 is the schematic diagram of the structure of the ground pressure connector; Figure 4 is the schematic diagram of the structure of the rubber pipe extrusion fixing head; Figure 5 is the schematic diagram of the structure of the injection flow restrictor; Figure 6 is the schematic diagram of the structure of the upper packer; Figure 7 is the schematic diagram of the present application when injecting acidizing agent or chemical sand consolidation agent; Figure 8 is the schematic diagram of the present application when washing well; In the figure: blind plug 1, lower packer 2, injection flow restrictor 3, upper packer 4, flow connector 5, continuous low-carbon alloy steel pipe 6, continuous rubber pipe 7, ground pressure connector 8, washing well external connector 9, oil layer 10, casing 11, rubber pipe extrusion fixing head 12, injector 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 cylinder embedded part 4.2, expansion rubber cylinder 4.3, packer central pipe 4.4, packer lower connector 4.5, liquid passage hole 4.6, washing well 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 passage 8.1, rubber pipe fixing groove 12.1, fixing head external thread 12.2. DETAILED DESCRIPTION

[0016] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0017] Reference Figures 1-3The application discloses a concentric soft and hard combined coiled tubing acidification and chemical sand control device, which is characterized by comprising a blind plug 1, a lower packer 2, an injection flow restrictor 3, an upper packer 4, the injection flow restrictor 3 being located between the lower packer 2 and the upper packer 4, and the bottom being provided with the blind plug 1, wherein the device further comprises a flow-through connector 5, a continuous low-carbon alloy steel pipe 6, a continuous rubber pipe 7 and a ground pressing connector 8, 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 comprises 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 at the outside and connected with the continuous rubber pipe 7 at the inside.

[0018] Referring to Figure 2 The well flushing connector 5.1 comprises a connector body 5.1.2, a setting device 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 in the outer wall of the connector body 5.1.2, a one-way valve formed by 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 the continuous low-carbon alloy steel pipe 6, the lower side of the continuous low-carbon alloy steel pipe 6 is provided with the setting device 5.1.3, the upper end of the plug 5.1.4 is connected with the setting device 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 the continuous rubber pipe 7.

[0019] The spring seat 5.1.6 is provided with a hollow structure in the middle, and the base 5.1.7 is provided with a through hole, so that the well flushing fluid can flow into the inner cavity of the flow-through connector 5 after the plug 5.1.4 and the spring 5.1.5 are opened.

[0020] 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 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 in a threaded mode.

[0021] Referring to Figure 3 and Figure 4The lower end of the ground pressing joint 8 is connected with the upper end of the continuous low-carbon alloy steel pipe 6 through threading, the inner cavity of the ground pressing joint 8 is connected with the upper end of the continuous rubber pipe 7 through the rubber pipe extrusion fixing head 12, the well flushing external joint 9 is installed on the outer wall of the ground pressing joint 8, and the well flushing external joint 9 is communicated with the annulus between the continuous low-carbon alloy steel pipe 6 and the continuous rubber pipe 7 through the connecting channel 8.1.

[0022] The upper part of the rubber pipe extrusion fixing head 12 is provided with a fixing head outer 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.

[0023] Referring to Figure 5 The injection throttler 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; the upper end of the central pipe 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 inner thread 3.1.1, and the lower end is provided with an outer expansion cover 3.1.2; the central pipe 3.5 on the inner side of the outer expansion cover 3.1.2 is provided with the liquid injection port 3.6; the sealing piston ring 3.2 is installed at the annulus between the outer expansion cover 3.1.2 and the central pipe 3.5; the lower end of the sealing piston ring 3.2 is connected with the pressure adjusting cap 3.4 through the return spring 3.3; the pressure adjusting cap 3.4 is connected with the central pipe 3.5 through threading; the tightness of the return spring 3.3 is adjusted through the pressure adjusting cap 3.4, so as to further adjust the opening pressure of the sealing piston ring 3.2.

[0024] Referring to Figure 6 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 pipe 4.4 and a packer lower joint 4.5; one end of the packer central pipe 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 part of the packer central pipe 4.4; the packer central pipe 4.4 is provided with a liquid passage hole 4.6; part of the liquid in the packer central pipe 4.4 enters the annulus between the expansion rubber sleeve 4.3 and the packer central pipe 4.4 through the liquid passage hole 4.6, so as to push the expansion rubber sleeve 4.3 to expand to the inner wall of the casing 11 in the well to realize the sealing effect.

[0025] The K344 packer further comprises a rubber sleeve pre-embedded part 4.2; the rubber sleeve pre-embedded part 4.2 is arranged at both ends of the expansion rubber sleeve 4.3; the upper end of the expansion rubber sleeve 4.3 is connected with the lower end of the packer upper joint 4.1 through the rubber sleeve pre-embedded part 4.2; and the lower end of the expansion rubber sleeve 4.3 is connected with the upper end of the packer lower joint 4.5 through the rubber sleeve pre-embedded part 4.2.

[0026] The application mentioned the use method of the concentric soft and hard combined coiled tubing acidification and chemical sand control device, and the technical scheme is as follows: I. Assembling the concentric soft and hard combined coiled tubing acidification and chemical sand control device: Firstly, 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 connection head 5, the upper end of the well washing connector 5.1 is connected to the outer side of the continuous low-carbon alloy steel pipe 6, and the inner side is connected to the continuous rubber pipe 7; then, the upper packer 4, the injection flow restrictor 3 and the lower packer 2 are sequentially connected through the single-layer oil pipe at the lower end of the flow connection head 5, and the 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 casing 11 is lowered into the well and reaches the designed position; II. When injecting the acidizing agent or the chemical sand consolidation agent: Referring to Figure 7 , when the acidizing agent is injected into the inner cavity of the surface pressure joint 8 at the surface wellhead to acidize the formation, the acidizing agent enters the flow connection head 5 along the continuous rubber pipe 7, and since the flow connection head 5 is provided with the spring 5.1.5 and the plug 5.1.4 to form a one-way valve, the acidizing agent can only continue to flow downward along the single-layer oil pipe to the injection flow restrictor 3, and since the opening pressure of the injection flow restrictor 3 is smaller than that 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 sealed with the inner wall of the casing 11; then, the injection flow restrictor 3 is opened, the acidizing agent pushes open the sealing piston ring 3.2 of the flow restrictor 3, sprays out along the injection liquid outlet 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; the process of injecting the chemical sand consolidation agent is the same as the above acidizing process; III. After injecting the acidizing agent or the chemical sand consolidation agent, the well needs to be washed: Referring to Figure 8 , the well washing liquid is injected into the well washing external joint 9 on one side of the surface pressure joint 8 at the surface wellhead, and the well washing liquid flows downward along the annulus between the continuous low-carbon alloy steel pipe 6 and the continuous rubber pipe 7 until the well washing liquid reaches the flow connection head 5; when the pressure of the well washing liquid 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 liquid enters the inner cavity of the flow connection head 5, and then flows upward in the reverse direction along the inner cavity of the continuous rubber pipe 7; under the common pressure of the well washing liquid and the mixture of the acidizing agent or the chemical sand consolidation agent 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 balance, until the acidizing agent or the chemical sand consolidation agent in the inner cavity of the continuous rubber pipe 7 and the inner cavity of the single-layer oil pipe below the flow connection head 5 is sent out to the surface wellhead under the negative pressure of the well washing liquid, thereby completing the well washing process.

[0027] 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-hard combined coiled tubing acidizing and chemical sand control device, comprising a blind plug (1), a lower packer (2), an injection throttle (3), and an upper packer (4), wherein the injection throttle (3) is located between the lower packer (2) and the upper packer (4), and the blind plug (1) is installed at the bottom, characterized in that: It also includes a flow connector (5), a continuous low-carbon alloy steel pipe (6), a continuous rubber hose (7), and a ground pressure testing joint (8). The upper part of the flow connector (5) is connected to a concentric soft and hard combined continuous tubing composed of a continuous low-carbon alloy steel pipe (6) and a continuous rubber hose (7), and the ground pressure testing joint (8) is connected to the top of the concentric soft and hard combined continuous tubing. The flow connector (5) includes a well washing connector (5.1), a connecting cap (5.2), and a lower connector (5.3). The lower end of the well washing connector (5.1) is connected to the lower connector (5.3) through the connecting cap (5.2). The upper outer side of the well washing connector (5.1) is connected to the continuous low-carbon alloy steel pipe (6), and the inner side is connected to the continuous rubber hose (7).

2. The concentric soft-hard combined coiled tubing acidizing and chemical sand control device according to claim 1, characterized in that: The well-washing connector (5.1) includes a connector body (5.1.2), a setting device (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). The outer wall of the connector body (5.1.2) has multiple connecting holes. A one-way valve composed of a plug (5.1.4), a spring (5.1.5), and a spring seat (5.1.6) is installed in each connecting hole. A continuous low-carbon alloy steel pipe (6) is connected to the top of the connector body (5.1.2). The setting device (5.1.3) is installed on the lower side of the continuous low-carbon alloy steel pipe (6). The upper end of the plug (5.1.4) is connected to the setting device (5.1.3). The inner wall of 5.1.2) is connected to the lower end of the continuous rubber tube (7).

3. The concentric soft-hard combined coiled tubing acidizing and chemical sand control device according to claim 2, characterized in that: The spring seat (5.1.6) has a hollow structure in the middle, and the base (5.1.7) is provided with a through hole for the well washing fluid to enter the inner cavity of the flow connector (5) after the plug (5.1.4) and spring (5.1.5) are opened.

4. The concentric soft-hard combined coiled tubing acidizing and chemical sand control device according to claim 3, characterized in that: The lower side of the outer wall of the well washing connector (5.1) is provided with a protrusion. 5.1.1) The lower connector (5.3) has a raised connecting part (5.3.1) in the middle of its outer wall, and the raised connecting part (5.3.1) has an external thread. The upper part of the connecting cap (5.2) presses against the raised part (5.1.1) of the well washing connector (5.1), and the lower part is connected to the raised connecting part (5.3.1) of the lower connector (5.3) by a thread.

5. The concentric soft-hard combined coiled tubing acidizing and chemical sand control device according to claim 4, characterized in that: The lower end of the ground pressure joint (8) is connected to the upper end of the continuous low carbon alloy steel pipe (6) by a thread. The inner cavity of the ground pressure joint (8) is connected to the upper end of the continuous rubber pipe (7) through the rubber pipe extrusion fixing head (12). The well washing external joint (9) is installed on the outer wall of the ground pressure joint (8). The well washing external joint (9) is connected to the annulus between the continuous low carbon alloy steel pipe (6) and the continuous rubber pipe (7) through the connecting channel (8.1).

6. The concentric soft-hard combined coiled tubing acidizing and chemical sand control device according to claim 5, characterized in that: The injection throttle (3) includes an injector upper connector (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 an injection port (3.6). The injector upper connector (3.1) is installed at the upper end of the central tube (3.5). The upper end of the injector upper connector (3.1) is provided with an internal thread (3.1.1), and the lower end is provided with an outer expansion cover (3.1.2). The central tube (3.6) inside the outer expansion cover (3.1.2) is... .5) is provided with an injection port (3.6). A sealing piston ring (3.2) is installed in the annular space between the outer expansion cover (3.1.2) and the central tube (3.5). 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) by a thread. The tightness of the return spring (3.3) is adjusted by the pressure adjusting cap (3.4), thereby adjusting the opening pressure of the sealing piston ring (3.2).

7. The concentric soft and hard combined coiled tubing acidizing and chemical sand control device according to claim 6, characterized in that: The lower packer (2) and upper packer (4) are K344 packers. The K344 packer includes an upper packer connector (4.1), an expansion sleeve (4.3), a packer center tube (4.4), and a lower packer connector (4.5). The upper packer connector (4.1) is installed at one end of the packer center tube (4.4), and the lower packer connector (4.5) is installed at the other end. The expansion sleeve (4.3) is installed in the middle of the packer center tube (4.4), and a liquid passage hole (4.6) is provided on the packer center tube (4.4). A portion of the liquid in the packer center tube (4.4) enters the annulus between the expansion sleeve (4.3) and the packer center tube (4.4) through the liquid passage hole (4.6), thereby pushing the expansion sleeve (4.3) to expand to the inner wall of the casing (11) downhole to achieve the sealing effect.

8. The concentric soft-hard combined coiled tubing acidizing and chemical sand control device according to claim 7, characterized in that: The K344 packer also includes a rubber tube pre-embedded part (4.2). The rubber tube pre-embedded parts (4.2) are provided at both ends of the expansion rubber tube (4.3). The upper end of the expansion rubber tube (4.3) is connected to the lower end of the upper connector (4.1) of the packer through the rubber tube pre-embedded part (4.2), and the lower end of the expansion rubber tube (4.3) is connected to the upper end of the lower connector (4.5) of the packer through the rubber tube pre-embedded part (4.2).

9. The method of using the concentric soft-hard combined coiled tubing acidizing and chemical sand control device according to claim 8, characterized in that: The process includes the following: I. Assemble a concentric soft and hard combined coiled tubing acidizing and chemical sand control device: First, the continuous rubber tube (7) is passed through the inner cavity of the continuous low carbon alloy steel tube (6) and connected to the flow connector (5). The upper outer side of the well washing connector (5.1) is connected to the continuous low carbon alloy steel tube (6), and the inner side is connected to the continuous rubber tube (7). Then, at the lower end of the flow connector (5), the upper packer (4), the injection choke (3) and the lower packer (2) are connected in sequence through a single layer of tubing. A blind plug (1) is installed at the bottom to form a concentric soft and hard combined continuous tubing acidizing and chemical sand control device. Finally, the casing (11) is lowered into the well and reaches the designed position. II. When injecting acidifying agents or chemical sand-fixing agents: When acidizing the formation by injecting acidizing agent into the inner cavity of the surface pressure fitting (8) at the surface wellhead, the acidizing agent enters the flow connector (5) along the continuous rubber tube (7). Since the flow connector (5) is equipped with a one-way valve formed by a spring (5.1.5) and a plug (5.1.4), the acidizing agent can only continue to flow down along the single-layer tubing 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), Force, therefore, the expansion sleeves (4.3) of the upper packer (4) and the lower packer (2) expand and achieve a 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 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) to realize the acidizing process; the injection of chemical sand-fixing agent is the same as the above acidizing process; 3. When well washing is required after injecting acidizing agents or chemical sand-fixing agents: At the wellhead, the well-washing fluid is injected into the external well-washing connector (9) on one side of the surface pressure joint (8). 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 it reaches the flow 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) opens, and the well-washing fluid enters the inner cavity of the flow connector (5). Then, it flows along the continuous rubber pipe... (7) The inner cavity flows upward in the opposite direction. Under the combined pressure of the washing fluid and the acidizing agent or chemical sand-fixing agent mixture, the continuous rubber tube (7) expands and reaches equilibrium with the internal pressure of the annulus between the continuous low carbon alloy steel tube (6) and the continuous rubber tube (7). Until the acidizing agent or chemical sand-fixing agent in the inner cavity of the continuous rubber tube (7) and the single-layer tubing inner cavity below the flow connector (5) is sent to the surface wellhead under the negative pressure of the washing fluid, thus completing the washing process.

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