Water injection device for oil production wellhead

Abstract

The present application relates to the technical fields of oil extraction water injection, and more particularly to an oil extraction wellhead water injection device, comprising a mixing tank, a water inlet pipe and a first auxiliary pipeline are connected to a water inlet of the mixing tank, a mixing cavity and a reduced diameter cavity are arranged in the mixing tank from top to bottom, a conical hopper is fixedly connected in the mixing cavity, a plurality of first through grooves are formed in an inner wall of the reduced diameter cavity, the water inlet pipe is connected to a water inlet of a filter through a second auxiliary pipeline, the other end of the first auxiliary pipeline is connected to a water outlet of the filter, a water outlet pipe is connected to the water outlet of the filter, the water outlet pipe is connected to the water inlet of the filter through a third auxiliary pipeline, a dosing mechanism and a self-mixing mechanism are arranged on the mixing tank; the water and the medicine are automatically mixed when flowing, the spiral vortex is driven completely by the kinetic energy of the fluid itself, the three modes are flexibly switched, the addition of different medicines is adapted, and the pertinence and efficiency of the oil extraction water injection are improved.

Description

Technical Field

[0001] This invention relates to the field of water injection technology in oil production, and more specifically to a water injection device for oil wellheads. Background Technology

[0002] During crude oil extraction, formation pressure gradually decreases. Water injection can maintain formation pressure and prevent crude oil from becoming less fluid due to excessively low pressure. Water injection can also drive crude oil in the reservoir toward the production well, thereby improving crude oil recovery. For heterogeneous reservoirs, water injection can balance the pressure in different areas and optimize the flow path of crude oil.

[0003] Publication No. CN115382264A discloses a wellhead filtration device for water injection wells in oilfield development. Its structure includes: an injection end, a filter, a flow chamber, a base, and a balance block. The injection end is embedded in the upper end of the filter, the lower end of the filter communicates with the flow chamber, the base is fixed to the outer edge of the flow chamber, and the balance block is welded to both sides of the base. This invention further improves upon the filter by using a connecting frame and pull valve mounted on the splicing block at the side end of the filter screen limiting body. After a large amount of impurities accumulate on the filter screen surface, the filter screen can be directly pulled out from below the injection end by pulling, facilitating timely replacement and cleaning of the filter screen. This prevents clogging caused by the inability to replace the filter screen during use. Furthermore, the ball bearing effect of the surface auxiliary device on the limiting body replaces the original friction pulling effect, preventing damage to the surface precision caused by continuous friction and ultimately leading to unstable assembly.

[0004] In crude oil extraction water injection operations, existing equipment suffers from missing or inefficient mixing structures, failing to effectively mix chemicals and water, resulting in insufficient mixing uniformity, low chemical utilization, and a fixed and monotonous process. This makes it impossible to adjust the dosing and filtration sequence according to the characteristics of the chemicals, leading to poor adaptability. Furthermore, the fixed process results in energy waste when no chemicals are needed, inconvenient maintenance, and reliance on natural mixing or external stirring, which leads to high energy consumption and low mixing efficiency. This makes it impossible to meet the water injection requirements of different oil reservoirs and chemicals. Therefore, we propose a water injection device for oil wellheads. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides a water injection device for oil wellheads to solve the problems existing in the background art.

[0006] This invention provides the following technical solution: a water injection device for oil wellheads, comprising a mixing tank, an inlet pipe and a first auxiliary pipe connected to the inlet of the mixing tank, a mixing chamber and a narrowing chamber arranged from top to bottom inside the mixing tank, a conical bucket fixedly connected inside the mixing chamber, and several first through grooves opened on the inner wall of the narrowing chamber, the inlet pipe being connected to the inlet of a filter through a second auxiliary pipe, the other end of the first auxiliary pipe being connected to the outlet of the filter, the outlet of the filter being connected to an outlet pipe, the outlet pipe being connected to the inlet of the filter through a third auxiliary pipe, and the mixing tank being provided with a chemical dosing mechanism and a self-mixing mechanism, wherein chemical solution is added to the mixing chamber through the chemical dosing mechanism, and then after being mixed with the assistance of the self-mixing mechanism, it is connected to the outlet pipe to realize self-mixing of the chemical solution during flow.

[0007] The self-mixing mechanism includes a long pipe, an inner flow pipe, and an outlet pipe. The long pipe is fixedly connected to the bottom of the mixing tank. The reduced diameter cavity is located inside the long pipe. An internal threaded strip is provided inside the long pipe. The inner flow pipe is fixedly connected to the lower inner wall of the long pipe. A second through groove and an external threaded strip are provided on the circumferential surface of the inner flow pipe. The outlet pipe is located at the lower end of the long pipe and is connected to the water outlet pipe.

[0008] Furthermore, the dosing mechanism includes an annular pipe and atomizing nozzles. The annular pipe is located on the upper side of the mixing tank. The annular pipe injects medicine through the inlet pipe. Several atomizing nozzles are provided and are evenly distributed on the top of the mixing tank. The annular pipe is connected to several atomizing nozzles through a diversion pipe, thereby evenly injecting medicine into the mixing chamber.

[0009] Furthermore, the conical bucket has a mesh structure, and a flow guiding gap is formed between the conical surface of the conical bucket and the inner wall of the mixing chamber. The mesh aperture of the conical bucket is 0.5-2mm, and its mesh structure is woven from stainless steel wire, with an anti-rust coating on the surface of the wire.

[0010] Furthermore, a first valve is installed between the water inlet pipe and the water inlet of the mixing tank, a fifth valve is installed between the second auxiliary pipe and the water inlet pipe, and a fourth valve is installed between the first auxiliary pipe and the water outlet of the filter.

[0011] Furthermore, a second valve and a third valve are provided on the water outlet pipe. The third valve is located between the water outlet pipe and the water outlet of the filter. A sixth valve is provided between the water outlet pipe and the third auxiliary pipe. The second valve is located between the third valve and the sixth valve.

[0012] Furthermore, the internal threaded strip extends spirally along the inner wall of the long tube, and the external threaded strip extends spirally along the surface of the inner flow tube, with the internal threaded strip and the external threaded strip having the same spiral direction.

[0013] Furthermore, the first through groove is arranged in a ring array on the inner wall of the reduced diameter cavity, the inner diameter of the connection between the mixing cavity and the reduced diameter cavity gradually decreases from top to bottom, and the reduced diameter cavity extends into the long tube and is spliced ​​with the inner flow tube.

[0014] Furthermore, a flow guiding gap is formed between the conical surface of the conical bucket and the inner wall of the mixing chamber. The mesh aperture of the conical bucket is 0.5-2mm, and its mesh structure is woven from stainless steel wire with an anti-rust coating on the surface of the wire.

[0015] The technical effects and advantages of this invention are as follows:

[0016] 1. This invention, by incorporating a dosing mechanism and a self-mixing mechanism, facilitates the uniform atomization and spraying of the medicine into the mixing chamber, increasing the contact area with water. Then, under the action of the internal and external threaded strips, the fluid kinetic energy generates a spiral vortex, enhancing the dynamic mixing of the medicine and water. The mixing efficiency is significantly improved compared to existing technologies, enabling automatic mixing of the medicine while it is flowing. It relies entirely on the fluid's own kinetic energy to drive the spiral vortex, eliminating the need for additional power devices such as stirring motors, and achieving a significant improvement in mixing efficiency without increasing energy consumption.

[0017] 2. This invention, through its multi-channel switchable fluid control structure, facilitates the control of different water flow paths via valve combinations, enabling flexible switching between three modes: direct filtration water injection, filtration followed by chemical mixing, and chemical mixing followed by filtration. This adapts to the addition requirements of different chemicals, improves the targeting and efficiency of oilfield water injection, and dynamically adjusts the dosing sequence according to the characteristics of the chemicals, thereby enhancing the scientific nature of the process.

[0018] 3. The present invention, by providing a conical hopper, facilitates the separation of fluid into fine streams under the action of the mesh of the conical hopper, generating a strong shearing force. This shearing force can break larger drug droplets or water clumps into micron-sized particles, increasing the contact area and improving the mixing uniformity. At the same time, the obstruction effect of the mesh structure on the fluid will induce turbulence, further promoting the collision and diffusion of drug and water, and enhancing the mixing efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 This is a side view of the structure of the present invention.

[0021] Figure 3 This is a schematic cross-sectional view of the present invention.

[0022] Figure 4 This is a schematic diagram of the drug dispensing mechanism of the present invention.

[0023] Figure 5 This is a schematic diagram of the conical bucket structure of the present invention.

[0024] Figure 6 This is a schematic diagram of the self-mixing mechanism of the present invention.

[0025] Figure 7 This is a flowchart illustrating the usage of the present invention.

[0026] The attached figures are labeled as follows: 1. Mixing tank; 101. Mixing chamber; 102. Reduction chamber; 103. First through channel; 2. Filter; 3. Inlet pipe; 301. First valve; 4. Outlet pipe; 401. Second valve; 402. Third valve; 5. First auxiliary pipe; 501. Fourth valve; 6. Second auxiliary pipe; 601. Fifth valve; 7. Third auxiliary pipe; 701. Sixth valve; 8. Dosing mechanism; 801. Ring pipe; 802. Inlet pipe; 803. Diverter pipe; 804. Atomizing nozzle; 9. Self-mixing mechanism; 901. Long pipe; 902. Internally threaded strip; 903. Inner flow pipe; 904. Externally threaded strip; 905. Second through channel; 906. Outlet pipe; 11. Conical hopper. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The water injection device for oil wellheads involved in the present invention is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Reference Figures 1-7 This invention provides a water injection device for oil wellheads, including a mixing tank 1. The inlet of the mixing tank 1 is connected to an inlet pipe 3 and a first auxiliary pipe 5. The mixing tank 1 is provided with a mixing chamber 101 and a narrowing chamber 102 arranged from top to bottom. A conical bucket 11 is fixedly connected in the mixing chamber 101. Several first through grooves 103 are opened on the inner wall of the narrowing chamber 102. The inlet pipe 3 is connected to the inlet of a filter 2 through a second auxiliary pipe 6. The other end of the first auxiliary pipe 5 is connected to the outlet of the filter 2. The outlet of the filter 2 is connected to an outlet pipe 4. The outlet pipe 4 is connected to the inlet of the filter 2 through a third auxiliary pipe 7. The mixing tank 1 is provided with a chemical dosing mechanism 8 and a self-mixing mechanism 9. Chemical solution is added to the mixing chamber 101 through the chemical dosing mechanism 8. After being mixed with the assistance of the self-mixing mechanism 9, it is connected to the outlet pipe 4 to realize the self-mixing of the chemical solution during flow.

[0029] The self-mixing mechanism 9 includes a long pipe 901, an inner flow pipe 903, and an outlet pipe 906. The long pipe 901 is fixedly connected to the bottom of the mixing tank 1. The reduced diameter cavity 102 is located inside the long pipe 901. An internal threaded strip 902 is provided inside the long pipe 901. The inner flow pipe 903 is fixedly connected to the lower inner wall of the long pipe 901. A second through groove 905 and an external threaded strip 904 are provided on the circumferential surface of the inner flow pipe 903. The outlet pipe 906 is located at the lower end of the long pipe 901 and is connected to the water outlet pipe 4.

[0030] In this embodiment, it should be specifically explained that: the mixing tank 1 is used to mix the chemicals, and the filter 2 is used to filter the water. In the water injection process at the wellhead of an oil well, filtration is usually an essential step. Its purpose is to remove suspended solids, colloids, oils and other impurities from the water to avoid damage to the injection well, formation and oil production equipment. The inlet pipe 3 is used to introduce water. After mixing and filtration, the water enters the outlet pipe 4 and is finally injected into the wellhead. The first auxiliary pipe 5 is used to introduce the water filtered by the filter 2 into the mixing tank 1. The chemical dosing mechanism 8 is used to add chemicals. Whether chemicals must be added for water injection at the wellhead of an oil well depends on the water quality of the injection water source, the characteristics of the reservoir and the development needs. If the water source, such as deep groundwater, already meets the reservoir water injection standards in terms of oil content, suspended solids, bacteria and other indicators, and the formation is not prone to scaling and has no risk of microbial contamination, water can be injected directly without the need for additional chemicals. Otherwise, chemicals need to be added.

[0031] The main difference between this embodiment and the prior art lies in the use of a multi-channel switchable fluid control structure and a self-mixing enhancement mechanism in this embodiment, specifically:

[0032] Multi-channel switchable fluid control structure, see [link / reference] Figure 7When no chemicals need to be added, the fifth valve 601 and the third valve 402 should be opened. At this time, the inlet pipe 3, the second auxiliary pipe 6, the filter 2, and the outlet pipe 4 form the first set of channels. Water directly enters the filter 2 through the second auxiliary pipe 6, and after being filtered by the filter 2, it enters the outlet pipe 4, and then water is directly added. When chemicals need to be added, there are two situations: one is that the chemicals need to be filtered before being added, such as bactericides and corrosion inhibitors; the other is that chemicals need to be added before filtration, such as flocculants and filter aids. When filtering is done before adding chemicals, the fifth valve 601, the fourth valve 501, and the second valve 401 should be opened. At this time, the inlet pipe 3, the second auxiliary pipe 6, the filter 2, the first auxiliary pipe 5, the mixing tank 1, the self-mixing mechanism 9, and the outlet pipe 4 form the second set of channels. Water enters the filter 2 through the second auxiliary pipe 6, and after being filtered by the filter 2, it enters the mixing tank 1 through the first auxiliary pipe 5. Inside tank 1, the dosing mechanism 8 adds chemicals to the mixing chamber 101. The water and chemicals mix in the self-mixing mechanism 9 and finally enter the outlet pipe 4 to discharge the injected water. When chemicals are added first and then filtered, the first valve 301, the sixth valve 701, and the third valve 402 need to be opened. At this time, the inlet pipe 3, mixing tank 1, self-mixing mechanism 9, outlet pipe 4, third auxiliary pipe 7, filter 2, and outlet pipe 4 form a third set of channels. Water first enters the mixing tank 1 and mixes with chemicals, then flows through the outlet pipe 4 and the third auxiliary pipe 7 into the filter 2. After being filtered by the filter 2, it returns to the outlet pipe 4 and is discharged. By controlling different water flow paths through valve combinations, the three modes of direct filtration injection, chemical mixing after filtration, and chemical mixing followed by filtration can be flexibly switched to adapt to the addition requirements of different chemicals, improve the targeting and efficiency of oilfield water injection, and dynamically adjust the dosing sequence according to the characteristics of the chemicals to improve the scientific nature of the process.

[0033] Self-mixing enhancement mechanism: Traditional drug mixing requires a separate stirring device and varying stirring times to obtain a mixed water, resulting in long waiting times and cumbersome pipeline installation. In this solution, the drug is atomized by the dosing mechanism 8 and enters the mixing chamber 101. A conical hopper 11 is designed within the mixing chamber 101. The conical surface of the hopper guides the fluid to diffuse outwards, preventing fluid accumulation in the central area and achieving uniform flow distribution. The diameter of the narrowing chamber 102 is smaller than that of the mixing chamber 101, causing a "Venturi effect" as the fluid passes through. The flow velocity gradually increases from the mixing chamber 101 to the narrowing chamber 102. This increased velocity leads to enhanced fluid shear force, further breaking down the drug-water mixture into smaller molecular clusters. Combined with the internal... The first through-slot 103, distributed in a ring array on the wall, allows the fluid to undergo preliminary mixing before entering the self-mixing mechanism 9. When entering the long pipe 901, the water generates a strong vortex under the spiral action of the internal threaded bar 902 and the external threaded bar 904, which effectively improves the mixing uniformity and enables automatic mixing of the medicine and water during flow. It relies entirely on the fluid's own kinetic energy to drive the spiral vortex, eliminating the need for additional power devices such as stirring motors. Compared with existing mixing equipment that requires external power, it reduces energy consumption by 15%-20% and reduces equipment maintenance costs. It achieves a significant improvement in mixing efficiency without increasing energy consumption and works in synergy with multi-channel process control, filling the gap in the field of dynamic self-mixing technology.

[0034] It should be noted that the above valves are in the closed state by default, ensuring that water flows along the set path.

[0035] The above structure is the main structure of this embodiment, which solves the problems of uneven mixing of chemicals and water, low mixing efficiency, and fixed process that cannot adapt to different chemical addition requirements in the water injection device at the oil wellhead. The filter 2 is an existing structure. The specific structure and connection method of the chemical dosing mechanism 8 are not described in detail in this embodiment. In addition, water filtration and chemical mixing are also existing technologies. Therefore, this application does not make detailed limitations.

[0036] Reference Figure 4 The dosing mechanism 8 includes an annular pipe 801 and atomizing nozzles 804. The annular pipe 801 is located on the upper side of the mixing tank 1. The annular pipe 801 injects medicine through the inlet pipe 802. Several atomizing nozzles 804 are provided and are evenly distributed on the top of the mixing tank 1. The annular pipe 801 is connected to several atomizing nozzles 804 through a diversion pipe 803, thereby evenly injecting medicine into the mixing chamber 101.

[0037] In this embodiment, it should be specifically explained that: the function of the dosing mechanism 8 is to uniformly add liquid medicine into the mixing chamber 101. The annular pipe 801 is arranged in a ring around the central axis of the mixing tank 1 and is connected to the external medicine tank through the inlet pipe 802. After the liquid medicine flows into the annular pipe 801 through the inlet pipe 802, it can be evenly distributed in the annular pipe 801, providing a stable source of medicine for subsequent diversion to each atomizing nozzle 804. Several atomizing nozzles 804 are evenly distributed in a ring array with the center of the top of the mixing tank 1 as the center, and are connected to the annular pipe 801 through the diversion pipe 803. This design allows the liquid medicine to be sprayed into the mixing chamber 101 simultaneously from multiple points on the top of the mixing tank 1, avoiding... To avoid the problem of excessively high local concentrations caused by a single spray point and to ensure the uniform spatial distribution of the medicine in the mixing chamber 101, the diversion pipe 803 consists of several pipes of equal diameter, one end of which is connected to the annular pipe 801 and the other end is connected to the atomizing nozzle 804. Since the medicine pressure in the annular pipe 801 is uniform and the diameter and length of the diversion pipe 803 are consistent, the amount of medicine sprayed by each atomizing nozzle 804 can be guaranteed to be consistent, further enhancing the uniformity of medicine addition. The atomizing nozzle 804 adopts a fine-hole spray structure to atomize the medicine into micron-sized droplets. After being sprayed into the mixing chamber 101, the contact area with water is more than 3 times larger than that of traditional liquid addition, which greatly improves the contact mixing effect.

[0038] Reference Figure 5 The conical bucket 11 has a mesh structure. A flow guiding gap is formed between the conical surface of the conical bucket 11 and the inner wall of the mixing chamber 101. The mesh aperture of the conical bucket 11 is 0.5-2mm. Its mesh structure is woven from stainless steel wire, and the surface of the wire is coated with an anti-rust coating.

[0039] In this embodiment, it should be specifically explained that when the mixture of medicine and water passes through the mesh of the conical hopper 11, the fluid is forced to be divided into fine streams, generating a strong shearing effect. This shearing force can break larger medicine droplets or water clumps into micron-sized particles, increasing the contact area and improving the mixing uniformity. At the same time, the obstruction effect of the mesh structure on the fluid will induce turbulence, further promoting the collision and diffusion of medicine and water, and enhancing the mixing efficiency. Through the innovation of mesh structure and guide gap, the mixing performance is improved without additional power consumption. Meanwhile, the material solution of stainless steel and anti-rust coating solves the pain point of easy corrosion of metal parts in existing devices.

[0040] Reference Figure 1 A first valve 301 is installed between the water inlet pipe 3 and the water inlet of the mixing tank 1, a fifth valve 601 is installed between the second auxiliary pipe 6 and the water inlet pipe 3, and a fourth valve 501 is installed between the first auxiliary pipe 5 and the water outlet of the filter 2.

[0041] In this embodiment, it should be specifically explained that: the first valve 301 is used to control the channel between the water inlet pipe 3 and the water inlet of the mixing tank 1; the fifth valve 601 is used to control the channel between the water inlet pipe 3 and the water inlet of the filter 2; and the fourth valve 501 is used to control the channel between the water outlet of the filter 2 and the mixing tank 1. By switching the first valve 301 and the fifth valve 601, the water can be switched to enter the filter 2 and the mixing tank 1 first. When the water enters the filter 2 first, it is filtered first; when the water enters the mixing tank 1 first, the chemicals are added and mixed first. The switching is automatic according to the process.

[0042] Reference Figure 1 The water outlet pipe 4 is equipped with a second valve 401 and a third valve 402. The third valve 402 is located between the water outlet pipe 4 and the water outlet of the filter 2. A sixth valve 701 is installed between the water outlet pipe 4 and the third auxiliary pipe 7. The second valve 401 is located between the third valve 402 and the sixth valve 701.

[0043] In this embodiment, it should be specifically explained that: the second valve 401 is located between the third valve 402 and the sixth valve 701 in the controlled water flow channel. When the second valve 401 is open and the third valve 402 and the sixth valve 701 are closed, the water flows directly out from the outlet pipe 4. When the second valve 401 is closed and the sixth valve 701 and the third valve 402 are open, the water can enter the third auxiliary pipe 7 from the outlet pipe 4, then enter the filter 2, and finally return to the outlet pipe 4 from the outlet of the filter 2, thus executing the mixing and filtering mode.

[0044] Reference Figure 6 The internal threaded bar 902 extends spirally along the inner wall of the long tube 901, and the external threaded bar 904 extends spirally along the surface of the inner flow tube 903, with the internal threaded bar 902 and the external threaded bar 904 having the same spiral direction.

[0045] In this embodiment, it should be specifically noted that the internal threaded bar 902 and the external threaded bar 904 have the same helical direction. When the fluid flows through them, the helical vortices generated are in the same direction, forming a "co-rotating" flow field. This design can avoid the mutual cancellation of vortices caused by opposite helical directions, thereby maximizing the fluid shear force. The co-rotating helical structure allows the fluid kinetic energy to be concentrated for enhanced mixing, rather than being consumed by vortex collision. Compared with the reverse helical structure, this design can reduce energy loss by 10%-15%, achieving efficient mixing without additional power. It achieves a significant improvement in mixing performance without additional energy consumption, which is a key breakthrough in the dynamic self-mixing technology of oil production water injection devices.

[0046] Reference Figure 6The first through groove 103 is arranged in a ring array on the inner wall of the narrowing cavity 102. The inner diameter of the connection between the mixing cavity 101 and the narrowing cavity 102 gradually decreases from top to bottom, and the narrowing cavity 102 extends into the long tube 901 and is spliced ​​with the inner flow tube 903.

[0047] In this embodiment, it should be specifically explained that: the first channel 103 is arranged in a ring array on the inner wall of the narrowing cavity 102, for example, 8-12 channels are arranged at equal angles along the circumference, so that the fluid in the mixing cavity 101 flows out of the narrowing cavity 102 in a uniform circumferential direction, avoiding fluid deviation or local flow velocity unevenness caused by a single outlet, and ensuring the stability of the flow field when entering the long pipe 901. The multiple channels of the ring array divide the fluid into multiple fine streams. Each fluid generates local acceleration when passing through the channel, forming shear force, which further breaks the mixture into smaller particles. With the spiral structure of the subsequent self-mixing mechanism 9, the mixing uniformity can be improved by about 10%. The narrowing cavity 102 is spliced ​​with the inner flow pipe 903 to achieve a smooth transition of the fluid path, which can avoid fluid turbulence or energy loss caused by structural abrupt changes, ensuring smooth flow of fluid from the narrowing cavity 102 to the long pipe 901, maintaining a high flow velocity state to enhance mixing.

[0048] Working principle of the invention:

[0049] The main problem solved by this embodiment is that the solution uses the dosing mechanism 8 and the self-mixing mechanism 9 to mix the medicine in the flow, which solves the problem of low efficiency caused by the need to stir the medicine and uneven self-mixing method. In addition, a multi-channel switchable fluid control structure is designed, which can be flexibly adapted to three modes by switching valves, which solves the problem that the existing water injection device has a fixed process, cannot adapt to different agent characteristics, has high process energy consumption and poor flexibility.

[0050] The specific steps are as follows:

[0051] S1, Direct Filter Water Injection Mode:

[0052] Suitable for applications requiring no chemical addition. Open the fifth valve 601 and the third valve 402, and close the first valve 301, the fourth valve 501, the second valve 401, and the sixth valve 701. The water flow path is: inlet pipe 3 → second auxiliary pipe 6 → filter 2 → outlet pipe 4, and then directly inject water.

[0053] S2, Post-filtration dosing mode:

[0054] This is suitable for disinfectants and other chemicals that require filtration before addition. Open the fifth valve 601, the fourth valve 501, and the second valve 401, and close the first valve 301, the third valve 402, and the sixth valve 701. The water flow path is: inlet pipe 3 → second auxiliary pipe 6 → filter 2 → first auxiliary pipe 5 → mixing chamber 101 of mixing tank 1 → dosing mechanism 8 to add chemicals → diameter reduction chamber 102 → self-mixing mechanism 9 to mix → outlet pipe 4, and then directly inject water.

[0055] S3, Post-dosing filtration mode:

[0056] This is suitable for flocculants and other chemicals that require filtration after dosing. Open the first valve 301, the sixth valve 701, and the third valve 402, and close the fifth valve 601, the fourth valve 501, and the second valve 401. The water flow path is: inlet pipe 3 → mixing chamber 101 of mixing tank 1 → dosing mechanism 8 to add chemicals → reducing diameter chamber 102 → self-mixing mechanism 9 to mix → outlet pipe 4 → third auxiliary pipe 7 → filter 2 → outlet pipe 4, and then directly inject water.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water injection device for oil wellheads, comprising a mixing tank (1), characterized in that: The inlet of the mixing tank (1) is connected to an inlet pipe (3) and a first auxiliary pipe (5). The mixing tank (1) is provided with a mixing chamber (101) and a narrowing chamber (102) from top to bottom. A conical bucket (11) is fixedly connected in the mixing chamber (101). Several first through grooves (103) are opened on the inner wall of the narrowing chamber (102). The inlet pipe (3) is connected to the inlet of the filter (2) through a second auxiliary pipe (6). The other end of the first auxiliary pipe (5) The filter (2) is connected to the outlet of the filter (2), and the outlet of the filter (2) is connected to the outlet pipe (4). The outlet pipe (4) is connected to the inlet of the filter (2) through the third auxiliary pipe (7). The mixing tank (1) is equipped with a dosing mechanism (8) and a self-mixing mechanism (9). The dosing mechanism (8) adds medicine to the mixing chamber (101), and then the self-mixing mechanism (9) assists in mixing before connecting to the outlet pipe (4) to achieve self-mixing of the medicine when it flows. The self-mixing mechanism (9) includes a long pipe (901), an inner flow pipe (903), and an outlet pipe (906). The long pipe (901) is fixedly connected to the bottom of the mixing tank (1). The reduced diameter cavity (102) is located inside the long pipe (901). An internal threaded strip (902) is provided inside the long pipe (901). The inner flow pipe (903) is fixedly connected to the lower inner wall of the long pipe (901). A second through groove (905) and an external threaded strip (904) are provided on the circumferential surface of the inner flow pipe (903). The outlet pipe (906) is located at the lower end of the long pipe (901) and connected to the water outlet pipe (4). A first valve (301) is provided between the water inlet pipe (3) and the water inlet of the mixing tank (1), a fifth valve (601) is provided between the second auxiliary pipe (6) and the water inlet pipe (3), and a fourth valve (501) is provided between the first auxiliary pipe (5) and the water outlet of the filter (2). The water outlet pipe (4) is provided with a second valve (401) and a third valve (402). The third valve (402) is located between the water outlet pipe (4) and the outlet of the filter (2). A sixth valve (701) is provided between the water outlet pipe (4) and the third auxiliary pipe (7). The second valve (401) is located between the third valve (402) and the sixth valve (701).

2. The water injection device for oil wellheads according to claim 1, characterized in that: The dosing mechanism (8) includes an annular pipe (801) and atomizing nozzles (804). The annular pipe (801) is located on the upper side of the mixing tank (1). The annular pipe (801) injects medicine through the inlet pipe (802). Several atomizing nozzles (804) are provided and are evenly distributed on the top of the mixing tank (1). The annular pipe (801) is connected to several atomizing nozzles (804) through a diversion pipe (803) so as to evenly inject medicine into the mixing chamber (101).

3. A water injection device for oil wellheads according to claim 2, characterized in that: The conical bucket (11) has a mesh structure. A flow guide gap is formed between the conical surface of the conical bucket (11) and the inner wall of the mixing chamber (101). The mesh aperture of the conical bucket (11) is 0.5-2mm. Its mesh structure is woven from stainless steel wire, and the surface of the wire is coated with an anti-rust coating.

4. A water injection device for oil wellheads according to claim 3, characterized in that: The internal threaded bar (902) extends spirally along the inner wall of the long tube (901), and the external threaded bar (904) extends spirally along the surface of the inner flow tube (903), with the internal threaded bar (902) and the external threaded bar (904) having the same spiral direction.

5. A water injection device for oil wellheads according to claim 4, characterized in that: The first through groove (103) is arranged in a ring array on the inner wall of the narrowing cavity (102). The inner diameter of the connection between the mixing cavity (101) and the narrowing cavity (102) gradually decreases from top to bottom, and the narrowing cavity (102) extends into the long pipe (901) and is spliced ​​with the inner flow pipe (903).

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