Two-stage fluid switching valve group and acid fracturing experiment multi-channel fluid switching device

Abstract

This invention discloses a two-stage fluid switching valve assembly and a multi-channel fluid switching device for acid fracturing experiments, belonging to the field of acid fracturing experimental technology. It solves the problem that existing sealed valves are easily deformed by high-pressure media, leading to internal leakage, cross-contamination, and mixing of media in different channels. The two-stage fluid switching valve assembly includes a valve core, a valve stem, and a valve body. A valve cover is bolted to the top of the valve body, and the valve stem passes through the valve cover. The top of the valve core is fixedly connected to the valve stem. An arc-shaped internal block is embedded in the inner wall of the valve body, and the inner wall of the internal block fits against the valve core. The valve core and valve body are rotatably connected. A through hole is provided on the valve core, and an inlet and an outlet are provided on the valve body. In this invention, the high-pressure hard seal between the valve core and the internal block ensures zero internal leakage blocking of the forward channel under high-pressure conditions, resulting in a long sealing life. High-frequency switching eliminates the risk of seal failure, making it suitable for the high-pressure fluid conditions of acid fracturing experiments.

Description

Technical Field

[0001] This utility model relates to the field of acid fracturing experimental technology, and in particular to a two-stage fluid switching valve group and a multi-channel fluid switching device for acid fracturing experiments. Background Technology

[0002] Acid fracturing experiments (also known as acid fracturing experiments) are laboratory experiments that simulate high-temperature and high-pressure underground formation conditions. Acid is used to fracture and etch core / rock samples under high pressure to evaluate acid formulation, construction parameters, and fracture conductivity. The experiments require the sequential introduction of different fluids, such as pre-fluid, acid, displacement fluid, and cleaning fluid. A single pipeline cannot meet this requirement; therefore, multi-channel switching is necessary to achieve the orderly injection of different media.

[0003] Existing fluid valves mostly use ordinary polytetrafluoroethylene / rubber soft seals. Under the high pressure of 20~70MPa in acid fracturing experiments, the internal seals of the valve body are easily deformed by the high-pressure medium, or even scratched by solid particles in the proppant-carrying fluid. This causes gaps between the valve core and the valve seat sealing surface, resulting in internal leakage of the medium in different channels under high pressure. The acid and fracturing fluid mix, which directly changes the experimental fluid formula, leading to distorted experimental results and affecting the overall experimental effect. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention provides a two-stage fluid switching valve assembly and a multi-channel fluid switching device for acid fracturing experiments, which solves the problem that existing sealed valves are easily deformed by high-pressure media, leading to internal leakage and mixing of media in different channels.

[0005] Firstly, in order to achieve the above objectives, the technical solution adopted by this utility model is as follows: A two-stage fluid switching valve assembly includes a valve core, a valve stem, and a valve body; a valve cover is bolted to the top of the valve body, and the valve stem passes through the valve cover; the top of the valve core is fixedly connected to the valve stem; an arc-shaped inner block is embedded in the inner wall of the valve body, the inner wall of the inner block is in contact with the valve core, and the valve core is rotatably connected to the valve body; a through hole is opened on the valve core, and an inlet and an outlet are opened on the valve body, with a connecting pipe fixedly connected to the inlet.

[0006] In this design, when the valve core is rotated and its through-hole is completely covered by the built-in block, all fluid channels are simultaneously blocked and isolated, preventing fluid from communicating between the various interfaces of the valve body. When the valve core is rotated until the through-hole aligns with the corresponding port of the valve body, the fluid path is re-established, enabling channel switching. The high-pressure hard seal between the valve core and the built-in block ensures zero internal leakage blocking of the forward channel under high-pressure conditions, resulting in a long sealing life. High-frequency switching eliminates the risk of seal failure, making it suitable for high-pressure fluid conditions in acid fracturing experiments.

[0007] Furthermore, a drain branch pipe is fixedly connected to the bottom of the connecting pipe, a reinforcing pipe is fixedly connected to the outer ring surface of the connecting pipe, a positioning pipe is threadedly connected to the outer ring surface of the reinforcing pipe, and a limit ring is connected to one end of the positioning pipe; an inlet check valve is fixedly connected to the inner ring surface of the limit ring.

[0008] In this design, a one-way valve is installed at the inlet to prevent backflow of the medium and ensure that the fluid flows into the valve assembly in the forward direction. This forms a double anti-mixing barrier design of "hard seal blocking + one-way valve check", which completely blocks internal leakage and backflow of the fluid, ensures the purity of the medium when switching between multiple channels, avoids contamination of the experimental fluid, thereby improving the accuracy of experimental data and ensuring experimental results.

[0009] Furthermore, connecting lugs are provided on the outer ring surfaces of the limiting ring and the positioning tube, and the connecting lugs of the limiting ring and the positioning tube are connected by bolts.

[0010] Furthermore, the valve core comprises, from the outside to the inside, a protective outer layer, a buffer connection layer, and a base layer. One side of the base layer is combined with the buffer connection layer, and one side of the buffer connection layer is combined with the protective outer layer.

[0011] In this design, the valve core adopts a three-layer composite structure. The base layer serves as the inner substrate, bearing the load impact of high-pressure fluid and providing basic acid and alkali corrosion protection. The buffer connection layer serves as an intermediate transition layer, eliminating the material stress difference between the base layer and the outer layer, preventing cracking and interlayer detachment of the weld overlay under high-temperature conditions, and improving the bonding strength of the composite layer. The outer protective layer serves as a functional layer directly facing the fluid, achieving wear resistance, erosion resistance, and scratch resistance under high-pressure conditions. Combined with the multi-stage conical surface structure, it achieves a high-pressure zero-internal-leakage hard seal.

[0012] Furthermore, the materials for the protective outer layer, the buffer connection layer, and the base layer are cobalt-based cemented carbide, nickel-based alloy, and duplex stainless steel, respectively.

[0013] Secondly, this utility model provides a multi-channel fluid switching device for acid fracturing experiments, including a two-stage fluid switching valve group; it also includes a high-pressure pump group, which is connected to a main inlet pipeline via a pipeline, and a main manual shut-off valve is installed on the main inlet pipeline; after passing through the main manual shut-off valve, the main inlet pipeline is divided into a first branch and a second branch, and a branch first storage tank is installed on the first branch, the outlet of which is connected to the inlet of the two-stage fluid switching valve group via a pipeline; a primary fluid distribution manifold and a branch second storage tank are sequentially installed on the second branch, the outlet of which is connected to the inlet of the two-stage fluid switching valve group via a pipeline; the outlet of the two-stage fluid switching valve group is connected to a mechanical buffer pressure stabilizing chamber, the end of which is connected to a main high-pressure check valve, the end of which is connected to a main outlet pipeline, and the end of the main outlet pipeline is connected to a simulation laboratory.

[0014] Furthermore, the outlet end of the primary fluid distribution manifold is also connected to a flushing and safety unit via a pipeline, and the end of the flushing and safety unit is connected to the main outlet pipeline.

[0015] Furthermore, on the first branch, a manual shut-off valve for the inlet of branch 1 and a manual shut-off valve for the outlet of branch 1 are respectively installed on the pipe body at both ends of the storage tank of branch 1; on the second branch, a manual shut-off valve for the inlet of branch 2 and a manual shut-off valve for the outlet of branch 2 are respectively installed on the pipe body at both ends of the storage tank of branch 2.

[0016] The beneficial effects of this utility model are: This invention features an internal block embedded in the valve body wall, a three-layer composite structure of the valve core, and a hard-seal design with the internal block, achieving zero internal leakage under high-pressure conditions, long seal life, and no risk of seal failure during high-frequency switching. It is suitable for high-pressure fluid conditions in acid fracturing experiments. The dual anti-mixing barrier design completely blocks internal fluid leakage and backflow, ensuring the purity of the medium during multi-channel fluid switching and preventing contamination of the experimental fluid, thereby improving the accuracy of experimental data and ensuring experimental results. This invention employs a two-level control architecture of primary distribution and secondary switching, enabling rapid and non-destructive switching between two experimental media. The switching process is free of mixing and pressure fluctuations, significantly improving the media switching efficiency of acid fracturing experiments. A multi-level isolation valve group is set up to achieve independent isolation and maintenance of each unit. Combined with the flushing and venting functions of the flushing and safety units, this ensures the cleanliness of the media during long-term system operation and enhances the safety redundancy of system operation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the two-stage fluid switching valve assembly in this utility model; Figure 2 This is a structural schematic diagram of the two-stage fluid switching valve assembly from another perspective in this utility model; Figure 3 This is a schematic diagram of the valve stem and valve body structure installation of the two-stage fluid switching valve assembly in this utility model; Figure 4 This is a schematic diagram of the internal built-in block structure of the two-stage fluid switching valve assembly in this utility model. Figure 5 This is a schematic diagram of the cross-sectional structure of the valve core of the two-stage fluid switching valve assembly in this utility model; Figure 6 This is a schematic diagram of the overall structure of the multi-channel fluid switching device for acid fracturing experiments according to this utility model.

[0018] Figure label: 1. High-pressure pump assembly; 2. Main inlet pipe; 3. Main manual shut-off valve; 4. Primary fluid distribution manifold; 5. Branch inlet manual shut-off valve; 6. Branch storage tank; 7. Branch outlet manual shut-off valve; 8. Branch inlet manual shut-off valve; 9. Branch storage tank; 10. Branch outlet manual shut-off valve; 11. Secondary fluid switching valve assembly; 111. Valve stem; 112. Valve cover; 113. Valve body; 114. Connecting pipe; 115. Inlet check valve; 116. Drain branch pipe; 117. Reinforcing pipe; 118. Limiting ring; 119. Positioning pipe; 12. Mechanical buffer pressure stabilizing chamber; 13. Main high-pressure check valve; 14. Main outlet pipe; 15. Flushing and safety unit; 16. Simulation laboratory; 17. Valve core; 171. Protective outer layer; 172. Buffer connection layer; 173. Base layer; 18. Internal block; Detailed Implementation The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The specific embodiments of the present invention are described below to facilitate understanding by those skilled in the art. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they fall within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0019] Example 1 like Figure 1 As shown, this embodiment provides a two-stage fluid switching valve assembly 11, which solves the problem that existing seals are easily deformed by high-pressure media, leading to internal leakage and mixing of media in different channels; specifically, it includes: Valve core 17, valve stem 111, valve body 113, valve cover 112, internal block 18, and connecting pipe 114; The valve body 113 has a valve cover 112 bolted to its top, and a valve stem 111 passes through the valve cover 112; the valve core 17 is fixedly connected to the valve stem 111 at its top. (Refer to...) Figure 4 An arc-shaped inner block 18 is fitted into the inner wall of the valve body 113. The inner wall of the inner block 18 is fitted with the valve core 17, and the valve core 17 is rotatably connected to the valve body 113. A through hole is provided on the valve core 17. (Refer to...) Figure 3 The valve body 113 has an inlet and an outlet, and a connecting pipe 114 is fixedly connected to the inlet.

[0020] like Figure 2As shown, a drain branch pipe 116 is fixedly connected to the bottom of the connecting pipe 114. A reinforcing pipe 117 is fixedly connected to the outer ring surface of the connecting pipe 114. A positioning pipe 119 is threadedly connected to the outer ring surface of the reinforcing pipe 117. One end of the positioning pipe 119 is connected to a limit ring 118. An inlet check valve 115 is fixedly connected to the inner ring surface of the limit ring 118. The inlet check valve 115 is provided to prevent backflow of the medium and ensure that the fluid flows into the valve assembly in the forward direction. By removing the bolts between the limit ring 118 and the positioning pipe 119, the connection between the limit ring 118 and the positioning pipe 119 can be released, thereby allowing the inlet check valve 115 to be disassembled and replaced.

[0021] like Figure 2 As shown, connecting lugs are provided on the outer ring surfaces of the limiting ring 118 and the positioning tube 119, and the connecting lugs of the limiting ring 118 and the positioning tube 119 are connected by bolts.

[0022] like Figure 5 As shown, the valve core 17 comprises, from the outside to the inside, a protective outer layer 171, a buffer connecting layer 172, and a base layer 173. One side of the base layer 173 is composite with the buffer connecting layer 172, and the other side of the buffer connecting layer 172 is composite with the protective outer layer 171. The valve core 17 adopts a three-layer composite structure. The base layer 173 serves as the inner substrate, bearing the load impact of high-pressure fluid and providing basic acid and alkali corrosion protection. The buffer connecting layer 172 serves as an intermediate transition layer, eliminating the material stress difference between the base layer 173 and the outer layer, preventing cracking and interlayer detachment of the weld overlay under high-temperature conditions, and improving the bonding strength of the composite layer. The protective outer layer 171 serves as a functional layer directly facing the fluid, achieving wear resistance, erosion resistance, and scratch resistance under high-pressure conditions, and, in conjunction with the multi-stage conical surface structure, achieving a high-pressure zero-internal-leakage hard seal.

[0023] Preferably, the protective outer layer 171, the buffer connecting layer 172, and the base layer 173 are made of cobalt-based hard alloy, nickel-based alloy, and duplex stainless steel, respectively.

[0024] The working principle of this embodiment: In this embodiment, the valve stem 111 is rotated by a manual / drive device, which drives the valve core 17 to rotate inside the valve body 113. When the through hole of the valve core 17 is completely covered by the built-in block 18, all fluid channels are blocked and isolated simultaneously, and the fluid cannot communicate between the various interfaces of the valve body 113. When the valve core 17 rotates to the point where the through hole is aligned with the corresponding port of the valve body 113, the fluid passage is re-established, and the channel switching is realized. The high-pressure hard seal of the valve core 17 and the built-in block 18 realizes zero internal leakage blocking of the positive channel. At the same time, the inlet check valve 115 only allows the fluid to flow into the valve group in the positive direction, preventing the medium from flowing back from the source, forming a double anti-mixing barrier of "hard seal blocking + check valve check".

[0025] Example 2 like Figure 6As shown, this example provides a multi-channel fluid switching device for acid fracturing experiments, including a high-pressure pump group 1, a main inlet pipeline 2, a main manual shut-off valve 3, a primary fluid distribution manifold 4, a branch inlet manual shut-off valve 5, a branch storage tank 6, a branch outlet manual shut-off valve 7, a branch inlet manual shut-off valve 8, a branch storage tank 9, a branch outlet manual shut-off valve 10, a secondary fluid switching valve group 11, a mechanical buffer pressure stabilizing chamber 12, a main high-pressure check valve 13, a main outlet pipeline 14, a flushing and safety unit 15, and a simulation laboratory 16.

[0026] The high-pressure pump unit 1 is connected to the main inlet pipeline 2 via a pipeline. The main inlet pipeline 2 is equipped with a main manual shut-off valve 3. After passing through the main manual shut-off valve 3, the main inlet pipeline 2 splits into a first branch and a second branch. The first branch is equipped with a branch-one storage tank 6, the outlet of which is connected to the inlet of the secondary fluid switching valve group 11 via a pipeline. The second branch is sequentially equipped with a primary fluid distribution manifold 4 and a branch-two storage tank 9, the outlet of which is connected to the inlet of the secondary fluid switching valve group 11 via a pipeline. The outlet of the secondary fluid switching valve group 11 is connected to a mechanical buffer pressure stabilizing chamber 12. The end of the mechanical buffer pressure stabilizing chamber 12 is connected to a main high-pressure check valve 13. The end of the main high-pressure check valve 13 is equipped with a main outlet pipeline 14, which is connected to a simulation laboratory 16.

[0027] The outlet end of the primary fluid distribution manifold 4 is also connected to a flushing and safety unit 15 via a pipe, and the end of the flushing and safety unit 15 is connected to the main outlet pipe 14.

[0028] On the first branch, a manual shut-off valve 5 for inlet and a manual shut-off valve 7 for outlet are respectively installed on the pipes at both ends of the storage tank 6 of branch one; on the second branch, a manual shut-off valve 8 for inlet and a manual shut-off valve 10 for outlet are respectively installed on the pipes at both ends of the storage tank 9 of branch two.

[0029] The working principle of this embodiment is as follows: In this embodiment, the high-pressure fluid output by the high-pressure pump group 1 is transported to the primary fluid distribution manifold 4 via the main inlet pipe 2 and the main manual shut-off valve 3. By controlling the on / off state of the branch inlet manual shut-off valve 5 and the branch inlet manual shut-off valve 8, the fluid is transported to the branch storage tank 6 and the branch storage tank 9 respectively, realizing the independent storage of the two experimental media. The output ends of the branch storage tank 6 and the branch storage tank 9 are connected to the secondary fluid switching valve group 11 via the branch outlet manual shut-off valve 7 and the branch outlet manual shut-off valve 10 respectively. By rotating the valve core 17 of the secondary valve group, the rapid switching and conduction of the fluid in the first branch and the second branch are realized, and a single medium fluid is output. The fluid output from the secondary fluid switching valve group 11 enters the mechanical buffer pressure stabilizing chamber 12. Through the volume buffer and mechanical damping of the chamber, the pressure of the output fluid is kept stable. The stabilized fluid is then transported to the simulation laboratory 16 via the main high-pressure check valve 13 and the main liquid outlet pipeline 14. The main high-pressure check valve 13 blocks the backflow of fluid in the experimental unit, protecting the upstream system. The flushing and safety unit 15 is connected to the primary fluid distribution manifold 4 and the main liquid outlet pipeline 14, respectively. It can realize the reverse flushing and residual liquid replacement of the system pipeline, and at the same time realize the safe release when the system is overpressured, ensuring the safe operation of the system.

[0030] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of this invention, and should be understood that the scope of protection of this invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on these technical teachings disclosed in this invention without departing from the essence of this invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A two-stage fluid switching valve assembly, characterized in that: The valve body includes a valve core (17), a valve stem (111), and a valve body (113). A valve cover (112) is bolted to the top of the valve body (113), and the valve stem (111) passes through the valve cover (112). The top of the valve core (17) is fixedly connected to the valve stem (111). An arc-shaped inner block (18) is embedded in the inner wall of the valve body (113), and the inner wall of the inner block (18) is attached to the valve core (17). The valve core (17) and the valve body (113) are rotatably connected. A through hole is provided on the valve core (17), and an inlet and an outlet are provided on the valve body (113). A connecting pipe (114) is fixedly connected to the inlet.

2. The two-stage fluid switching valve assembly according to claim 1, characterized in that: The bottom of the connecting pipe (114) is fixedly connected to a drain branch pipe (116), and a reinforcing pipe (117) is fixedly connected to the outer ring surface of the connecting pipe (114). A positioning pipe (119) is threadedly connected to the outer ring surface of the reinforcing pipe (117), and a limit ring (118) is connected to one end of the positioning pipe (119). A liquid inlet check valve (115) is fixedly connected to the inner ring surface of the limit ring (118).

3. The two-stage fluid switching valve assembly according to claim 2, characterized in that: Connecting lugs are provided on the outer ring surfaces of the limiting ring (118) and the positioning tube (119), and the connecting lugs of the limiting ring (118) and the positioning tube (119) are connected by bolts.

4. The two-stage fluid switching valve assembly according to claim 1, characterized in that: The valve core (17) includes, from the outside to the inside, a protective outer layer (171), a buffer connection layer (172) and a base layer (173). One side of the base layer (173) is combined with the buffer connection layer (172), and one side of the buffer connection layer (172) is combined with the protective outer layer (171).

5. The two-stage fluid switching valve assembly according to claim 4, characterized in that: The protective outer layer (171), buffer connection layer (172) and base layer (173) are made of cobalt-based hard alloy, nickel-based alloy and duplex stainless steel, respectively.

6. A multi-channel fluid switching device for acid fracturing experiments, comprising the two-stage fluid switching valve group (11) as described in claim 1; characterized in that: It also includes a high-pressure pump set (1), which is connected to the main liquid inlet pipeline (2) via a pipeline. The main liquid inlet pipeline (2) is equipped with a main manual shut-off valve (3). After passing through the main manual shut-off valve (3), the main liquid inlet pipeline (2) is divided into a first branch and a second branch. The first branch is equipped with a branch storage tank (6), and the outlet of the branch storage tank (6) is connected to the inlet of the secondary fluid switching valve set (11) via a pipeline. The second branch is equipped with a primary fluid distribution valve in sequence. The manifold (4) and the branch second liquid storage tank (9) are connected to the inlet of the secondary fluid switching valve group (11) through a pipeline. The outlet of the secondary fluid switching valve group (11) is connected to a mechanical buffer pressure stabilizing chamber (12). The end of the mechanical buffer pressure stabilizing chamber (12) is connected to a main high pressure check valve (13). The end of the main high pressure check valve (13) is provided with a main outlet pipeline (14). The end of the main outlet pipeline (14) is connected to a simulation laboratory (16).

7. The multi-channel fluid switching device for acid fracturing experiments according to claim 6, characterized in that: The outlet end of the primary fluid distribution manifold (4) is also connected to a flushing and safety unit (15) via a pipeline, and the end of the flushing and safety unit (15) is connected to the main outlet pipeline (14).

8. The multi-channel fluid switching device for acid fracturing experiments according to claim 6, characterized in that: On the first branch, a manual shut-off valve (5) for inlet liquid and a manual shut-off valve (7) for outlet liquid are respectively installed on the pipe body at both ends of the storage tank (6) of the first branch; on the second branch, a manual shut-off valve (8) for inlet liquid and a manual shut-off valve (10) for outlet liquid are respectively installed on the pipe body at both ends of the storage tank (9) of the second branch.

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