Water injection device for oil extraction wellhead

Abstract

The invention relates to the technical field of oil extraction and water injection, and particularly discloses a water injection device for an oil extraction wellhead, which comprises a mixing tank, a water inlet of the mixing tank is connected with a water inlet pipe and a first auxiliary pipeline, a mixing cavity and a reducing cavity are arranged in the mixing tank from top to bottom, a conical hopper is fixedly connected in the mixing cavity, and a plurality of first through grooves are formed in the inner wall of the reducing cavity; the water inlet pipe is connected with a water inlet of the filter through a second auxiliary pipeline, the other end of the first auxiliary pipeline is connected with a water outlet of the filter, the water outlet of the filter is connected with a water outlet pipe, the water outlet pipe is connected with the water inlet of the filter through a third auxiliary pipeline, and a dosing mechanism and a self-mixing mechanism are arranged on the mixing tank; automatic mixing of liquid medicine during flowing is achieved, spiral vortexes are driven completely depending on the kinetic energy of fluid, the three modes are flexibly switched, the adding requirements of different agents are met, and the pertinence and efficiency of oil extraction and water injection are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil extraction water injection, more particularly to an oil extraction wellhead water injection device. BACKGROUND

[0002] During crude oil extraction, the formation pressure gradually decreases, and water injection can maintain the formation pressure to avoid poor flowability of crude oil due to excessively low pressure. The injection of water can drive the crude oil in the reservoir to flow towards the production well, thereby improving the recovery rate of crude oil. For heterogeneous reservoirs, water injection can balance the pressure in each region and optimize the flow path of crude oil.

[0003] The oilfield exploitation water injection well mouth filtering device disclosed in the patent application with the publication number CN115382264A has a structure comprising a water injection end, a filter, a flow reversing cavity, a base, and a balancing block. The water injection end is embedded in the upper end of the filter, the lower end of the filter is connected to the flow reversing cavity, the base is fixed to the outer layer of the edge of the flow reversing cavity, and the balancing block is welded to the two sides of the base. The filter is further improved by the present application. When a large amount of impurities accumulates on the surface of the filter screen, the connecting frame equipped with the splicing block on the side end of the filter screen can be pulled out from below the water injection end by pulling the valve, thereby facilitating the timely replacement and cleaning of the filter screen. The original friction pulling effect is replaced by the ball effect equipped with the surface auxiliary device of the limiting body, which prevents the surface precision from being damaged due to continuous friction, thereby preventing the device from being unable to assemble stably. In the process of water injection during crude oil extraction, the existing devices have the problems of missing or inefficient mixing structure, which cannot effectively mix the medicine water and water, the mixing uniformity is insufficient, the utilization rate of the medicine is low, the process is fixed and single, the addition and filtration sequence cannot be adjusted according to the characteristics of the medicine, the adaptability is poor, and the fixed process leads to energy waste when no medicine is added, which is inconvenient to maintain, relies on natural mixing or external stirring, has high energy consumption and low mixing efficiency, and cannot meet the water injection needs of different reservoirs and medicines. Therefore, we propose an oil extraction wellhead water injection device. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, the present application provides an oil extraction wellhead water injection device to solve the problems existing in the background art.

[0005] The application provides the following technical scheme: a water injection device for an oil production well head, 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 the 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, medicine water is added into the mixing cavity through the dosing mechanism, and then the medicine water is self-mixed when flowing after being assisted by the self-mixing mechanism and is connected to the water outlet pipe.

[0006] The self-mixing mechanism comprises 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 in the long pipe, an internal thread strip is arranged in 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 thread strip are arranged on the circumferential surface of the inner flow pipe, and the outlet pipe is arranged at the lower end of the long pipe and is connected to the water outlet pipe.

[0007] Further, the dosing mechanism comprises an annular pipe and atomizing nozzles, the annular pipe is located on the upper side of the mixing tank, medicine water is injected into the annular pipe through a medicine inlet pipe, the atomizing nozzles are evenly distributed on the top of the mixing tank, and the annular pipe is connected to the atomizing nozzles through a shunt pipe, so that medicine water is uniformly injected into the mixing cavity.

[0008] Further, the conical hopper has a mesh structure, a flow guiding gap is formed between the conical surface of the conical hopper and the inner wall of the mixing cavity, the mesh hole diameter of the conical hopper is 0.5-2 mm, the mesh structure of the conical hopper is woven by stainless steel wires, and an anti-rust coating is arranged on the surface of the wires.

[0009] Further, a first valve is arranged between the water inlet pipe and the water inlet of the mixing tank, a fifth valve is arranged between the second auxiliary pipeline and the water inlet pipe, and a fourth valve is arranged between the first auxiliary pipeline and the water outlet of the filter.

[0010] Further, a second valve and a third valve are arranged 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 arranged between the water outlet pipe and the third auxiliary pipeline, and the second valve is located between the third valve and the sixth valve.

[0011] Further, the internal thread strip spirally extends along the inner wall of the long pipe, the external thread strip spirally extends along the surface of the inner flow pipe, and the spiral directions of the internal thread strip and the external thread strip are the same.

[0012] Further, the first through slot is arranged in an annular array on the inner wall of the reduced-diameter cavity, the inner diameter of the communication between the mixing cavity and the reduced-diameter cavity gradually reduces from top to bottom, and the reduced-diameter cavity extends to the long tube and is spliced with the inner flow pipe.

[0013] Further, a flow guide gap is formed between the conical surface of the conical hopper and the inner wall of the mixing cavity, the mesh aperture of the conical hopper is 0.5-2mm, the mesh structure is woven by stainless steel wires, and an anti-rust coating is arranged on the surface of the metal wires.

[0014] Technical effects and advantages of the present application: 1. The present application is provided with a dosing mechanism and a self-mixing mechanism, which is beneficial to uniformly atomize and spray the medicine water into the mixing cavity, increase the contact area with water, and then generate spiral vortex by fluid kinetic energy under the action of the inner threaded strip and the outer threaded strip, so as to strengthen the dynamic mixing of medicine water and water, greatly improve the mixing efficiency compared with the prior art, realize automatic mixing of medicine water during flow, completely rely on the kinetic energy of fluid to drive spiral vortex, and do not need to add stirring motor and other power devices, so as to realize significant improvement of mixing efficiency without increasing energy consumption.

[0015] 2. The present application is provided with a multi-channel switchable fluid control structure, which is beneficial to control different water flow paths through valve combination, realize flexible switching of three modes of direct filtering water injection, filtering and dosing mixing, and dosing mixing and filtering, adapt to the addition demand of different medicaments, improve the pertinence and efficiency of oil extraction water injection, dynamically adjust the addition sequence according to the characteristics of medicaments, and improve the scientific nature of the process.

[0016] 3. The present application is provided with a conical hopper, which is beneficial to divide the fluid into small flow bundles under the action of the mesh of the conical hopper, generate strong shearing effect, the shearing force can break large medicine water droplets or water flow groups into micron-sized particles, increase the contact area, improve the uniformity of mixing, the resistance of the mesh structure to fluid will cause turbulence, further promote the collision and diffusion of medicine water and water, and strengthen the mixing efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present application.

[0018] Figure 2 It is a schematic diagram of the side view structure of the present application.

[0019] Figure 3 It is a schematic diagram of the overall cross-sectional view of the present application.

[0020] Figure 4 It is a schematic diagram of the dosing mechanism of the present application.

[0021] Figure 5 It is a schematic diagram of the conical hopper structure of the present application.

[0022] Figure 6 A schematic diagram of the self-mixing mechanism of the present application.

[0023] Figure 7 A flow chart of the use of the present application.

[0024] The reference signs are: 1, mixing tank; 101, mixing cavity; 102, reduced diameter cavity; 103, first through slot; 2, filter; 3, water inlet pipe; 301, first valve; 4, water 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, annular pipe; 802, dosing pipe; 803, shunt pipe; 804, atomizing nozzle; 9, self-mixing mechanism; 901, long pipe; 902, internally threaded strip; 903, internal flow pipe; 904, externally threaded strip; 905, second through slot; 906, outlet pipe; 11, conical hopper. DETAILED DESCRIPTION

[0025] The technical solutions in the present application will be described clearly and completely in combination with the drawings in the present application. In addition, the forms of the structures described in the following embodiments are only examples. The water injection device for oil production wellhead to which the present application relates is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present application.

[0026] With reference to Figures 1-7 The present application provides a water injection device for oil production wellhead, which comprises a mixing tank 1, a water inlet pipe 3 and a first auxiliary pipe 5 are connected to the water inlet of the mixing tank 1, a mixing cavity 101 and a reduced diameter cavity 102 are arranged in the mixing tank 1 from top to bottom, a conical hopper 11 is fixedly connected in the mixing cavity 101, a plurality of first through slots 103 are formed in the inner wall of the reduced diameter cavity 102, the water inlet of a filter 2 is connected with the water inlet pipe 3 through a second auxiliary pipe 6, the other end of the first auxiliary pipe 5 is connected with the water outlet of the filter 2, a water outlet pipe 4 is connected with the water inlet of the filter 2 through a third auxiliary pipe 7, a dosing mechanism 8 and a self-mixing mechanism 9 are arranged on the mixing tank 1, water is added into the mixing cavity 101 through the dosing mechanism 8, and then the water is mixed with the aid of the self-mixing mechanism 9 and connected with the water outlet pipe 4 to realize self-mixing of the water during flow; The self-mixing mechanism 9 comprises 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 in the long pipe 901, the inner thread strip 902 is arranged in the long pipe 901, the inner flow pipe 903 is fixedly connected to the lower inner wall of the long pipe 901, the circumferential surface of the inner flow pipe 903 is provided with the second through slot 905 and the outer thread strip 904, and the outlet pipe 906 is arranged at the lower end of the long pipe 901 and connected with the water outlet pipe 4.

[0027] In the embodiment, it is particularly noted that the mixing tank 1 is used for mixing the medicine water, the filter 2 is used for filtering water, in the water injection process of the oil production wellhead, the filtering is usually an indispensable link, and the purpose is to remove the suspended solids, colloids, oils and other impurities in the water, so as to avoid damage to the water injection well, the formation and the oil production equipment, the water inlet pipe 3 is used for introducing water, the water is mixed and filtered and then enters the water outlet pipe 4, and finally is injected into the wellhead, and the first auxiliary pipeline 5 is used for introducing the water filtered by the filter 2 into the mixing tank 1, the medicine adding mechanism 8 is used for adding medicine water, whether the medicine water needs to be added in the water injection of the oil production wellhead needs to be comprehensively judged according to the water quality of the water injection source, the oil reservoir characteristics and the development demand, if the oil content, suspended solids, bacteria and other indexes of the water injection source such as deep groundwater meet the oil reservoir injection standard, and the formation is not easy to scale and has no microbial pollution risk, the water can be directly injected without additional medicine water, otherwise the medicine water needs to be added.

[0028] The main difference between the embodiment and the prior art is that the multi-channel switchable fluid control structure and the self-mixing reinforcement mechanism are adopted in the embodiment, and specifically in that: The multi-channel switchable fluid control structure, referring to Figure 7: When the medicine liquid is not needed to be added, the fifth valve 601 and the third valve 402 are opened, at this time, the water inlet pipe 3, the second sub-pipe 6, the filter 2 and the water outlet pipe 4 form the first group of channels, the water directly enters the filter 2 through the second sub-pipe 6, and then enters the water outlet pipe 4 after being filtered by the filter 2, and then directly injects water; When the medicine liquid is needed to be added, it can be divided into two cases, one medicine liquid needs to be filtered before adding the medicine liquid, for example, bactericides, corrosion inhibitors and the like, and the other needs to be filtered after adding the medicine liquid, for example, flocculants, filter aids and the like; When the medicine liquid is filtered before being added, the fifth valve 601, the fourth valve 501 and the second valve 401 are opened, at this time, the water inlet pipe 3, the second sub-pipe 6, the filter 2, the first sub-pipe 5, the mixing tank 1, the self-mixing mechanism 9 and the water outlet pipe 4 form the second group of channels, the water enters the filter 2 through the second sub-pipe 6, and then enters the mixing tank 1 through the first sub-pipe 5 after being filtered by the filter 2, at this time, the medicine liquid is added to the mixing cavity 101 by the medicine adding mechanism 8, the water and the medicine liquid are mixed in the self-mixing mechanism 9, and finally enter the water outlet pipe 4 to be discharged; When the medicine liquid is added before being filtered, the first valve 301, the sixth valve 701 and the third valve 402 are opened, at this time, the water inlet pipe 3, the mixing tank 1, the self-mixing mechanism 9, the water outlet pipe 4, the third sub-pipe 7, the filter 2 and the water outlet pipe 4 form the third group of channels, the water first enters the mixing tank 1 to be mixed with the medicine liquid, and then flows through the water outlet pipe 4 and the third sub-pipe 7 to enter the filter 2, and then is discharged again after being filtered by the filter 2, the valve combination controls different water flow paths, realizes flexible switching of three modes of direct filtration, filtration after adding medicine and mixing after adding medicine, adapts to the adding requirements of different medicine, improves the pertinence and efficiency of oil extraction and water injection, dynamically adjusts the adding sequence according to the characteristics of the medicine, and improves the scientific nature of the process; Self-mixing reinforcement mechanism: the traditional medicine water mixing needs to design a separate stirring device, and the mixed water is obtained after different stirring time, the waiting time is long, and the pipeline installation design is complicated. The medicine water is atomized into the mixing chamber 101 through the medicine adding mechanism 8, a conical hopper 11 is designed in the mixing chamber 101, the conical surface of the conical hopper can guide the fluid to diffuse to the four directions, avoid the fluid accumulation in the center area, realize uniform distribution, the diameter of the reduced diameter chamber 102 is smaller than that of the mixing chamber 101, which can produce "Venturi effect" when the fluid passes through, the flow rate gradually increases from the mixing chamber 101 to the reduced diameter chamber 102, the flow rate increases to enhance the shear force of the fluid, which can further break the medicine water and water mixture into smaller molecular groups. Cooperate with the first through groove 103 distributed in the inner wall ring array, the fluid realizes preliminary mixing before entering the self-mixing mechanism 9, when entering the long pipe 901, under the spiral action of the inner screw strip 902 and the outer screw strip 904, the water flow produces strong vortex when passing through, which effectively improves the mixing uniformity, realizes automatic mixing of medicine water during flow, completely relies on the kinetic energy of fluid to drive spiral vortex, without adding stirring motor and other power devices, the energy consumption of the existing technology is reduced by 15%-20%, and the equipment maintenance cost is reduced. On the premise of not increasing energy consumption, the mixing efficiency is significantly improved, and the multi-channel process control is formed, which fills the gap of the existing technology in the field of dynamic self-mixing.

[0029] It should be noted that the above-mentioned valve is in the default closed state, ensuring that the water flows along the set path.

[0030] The above structure is the main structure of the embodiment, which solves the problems of uneven mixing of medicine water and water, low mixing efficiency and fixed process in the oil wellhead water injection device, and the filter 2 is the existing structure. The specific structure and connection mode of the medicine adding mechanism 8 are not described in detail in this embodiment. In addition, the water filtration and medicine water mixing also belong to the existing technology, therefore, the application is not limited in detail.

[0031] Referring to Figure 4 The medicine adding mechanism 8 includes a ring-shaped pipe 801 and a plurality of atomizing nozzles 804. The ring-shaped pipe 801 is located on the upper side of the mixing tank 1, and the medicine water is injected through the medicine injection pipe 802. The atomizing nozzles 804 are evenly distributed on the top of the mixing tank 1, and the ring-shaped pipe 801 is connected with the atomizing nozzles 804 through the distribution pipe 803, so as to uniformly inject the medicine water into the mixing chamber 101.

[0032] In this embodiment, it needs to be specifically pointed out that: the function of the medicine adding mechanism 8 is to uniformly add medicine to the mixing chamber 101, the annular pipe 801 is arranged in a ring around the central axis of the mixing tank 1, connected with the external medicine tank through the medicine inlet pipe 802, and the medicine flows into the annular pipe 801 through the medicine inlet pipe 802, and can be uniformly distributed in the annular pipe 801, providing stable medicine source for subsequent shunting to each atomizing nozzle 804. A plurality of atomizing nozzles 804 are uniformly distributed in a ring array with the center of the top of the mixing tank 1 as the center, and are communicated with the annular pipe 801 through the shunt pipe 803. This design can make the medicine spray into the mixing chamber 101 from multiple points on the top of the mixing tank 1 at the same time, avoid the problem of local high concentration caused by single medicine spraying point, and ensure the uniformity of the spatial distribution of the medicine in the mixing chamber 101. The shunt pipe 803 is a plurality of equal-diameter pipes, one end of which is connected with the annular pipe 801, and the other end of which is connected with the atomizing nozzle 804. Since the pressure of the medicine in the annular pipe 801 is uniform, the pipe diameter and length of the shunt pipe 803 are consistent, which can ensure that the medicine spraying amount of each atomizing nozzle 804 is consistent, further strengthening the uniformity of medicine adding. The atomizing nozzle 804 adopts a fine hole spraying structure to atomize the medicine into micron-level droplets, which increases the contact area with water by more than 3 times compared with the traditional liquid addition after spraying into the mixing chamber 101, greatly improving the contact mixing effect.

[0033] Referring to Figure 5 , the conical hopper 11 is in a mesh structure, and a flow guiding gap is formed between the conical surface of the conical hopper 11 and the inner wall of the mixing chamber 101. The mesh hole diameter of the conical hopper 11 is 0.5-2mm, the mesh structure is woven by stainless steel wire, and a rust-proof coating is arranged on the surface of the metal wire.

[0034] In this embodiment, it needs to be specifically pointed out that: when the mixed liquid of medicine and water passes through the mesh hole of the conical hopper 11, the fluid is forced to be divided into fine flow bundles, and strong shearing action is generated. This shearing force can break larger medicine droplets or water flow groups into micron-level particles, increase the contact area, and improve the mixing uniformity. At the same time, the resistance of the mesh structure to the fluid will cause turbulence, further promoting the collision and diffusion of the medicine and water, and strengthening the mixing efficiency. Through the innovation of the mesh structure and the flow guiding gap, the mixing performance is improved without additional power consumption. At the same time, the material scheme of stainless steel and rust-proof coating solves the pain point of easy rusting of metal parts in the existing device.

[0035] Referring to Figure 1 , a first valve 301 is arranged between the water inlet pipe 3 and the water inlet of the mixing tank 1, a fifth valve 601 is arranged between the second sub-pipe 6 and the water inlet pipe 3, and a fourth valve 501 is arranged between the first sub-pipe 5 and the water outlet of the filter 2.

[0036] In this embodiment, it needs to be specifically pointed out that: the first valve 301 is used for controlling the passage between the water inlet pipe 3 and the water inlet of the mixing tank 1, the fifth valve 601 is used for controlling the passage between the water inlet pipe 3 and the water inlet of the filter 2, and the fourth valve 501 is used for controlling the passage between the water outlet of the filter 2 and the mixing tank 1. By switching the first valve 301 and the fifth valve 601, water can be switched to enter the filter 2 and the mixing tank 1 first. When water enters the filter 2 first, it is filtered first. When water enters the mixing tank 1 first, it is mixed with medicine first. According to the flow, it can be switched automatically.

[0037] Referring to Figure 1 , the second valve 401 and the third valve 402 are arranged on the water outlet pipe 4. The third valve 402 is located between the water outlet pipe 4 and the water outlet of the filter 2. The sixth valve 701 is arranged between the water outlet pipe 4 and the third sub-pipe 7. The second valve 401 is located between the third valve 402 and the sixth valve 701.

[0038] In this embodiment, it needs to be specifically pointed out that: the second valve 401 is located in the water flow passage controlled between the third valve 402 and the sixth valve 701. When the second valve 401 is opened and the third valve 402 and the sixth valve 701 are closed, the water flow is directly discharged from the water outlet pipe 4. When the second valve 401 is closed and the sixth valve 701 and the third valve 402 are opened, the water flow can enter the third sub-pipe 7 from the water outlet pipe 4, then enter the filter 2, and finally return to the water outlet pipe 4 from the water outlet of the filter 2, to execute the mixing and filtering mode.

[0039] Referring to Figure 6 , the inner thread strip 902 extends spirally along the inner wall of the long pipe 901, and the outer thread strip 904 extends spirally along the surface of the inner flow pipe 903. The spiral directions of the inner thread strip 902 and the outer thread strip 904 are the same.

[0040] In this embodiment, it needs to be specifically pointed out that: the inner thread strip 902 and the outer thread strip 904 have the same spiral direction, and the spiral vortex directions generated when the fluid flows are consistent, forming a "co-rotating" flow field. This design can avoid the mutual offset of vortexes caused by opposite spiral directions, maximize the fluid shear force, and make the fluid kinetic energy concentrate on strengthening mixing instead of being consumed in vortex offset. Compared with the opposite spiral, this design can reduce 10%-15% of energy loss, realize high-efficiency mixing without additional power, and significantly improve the mixing performance without additional energy consumption. It is a key breakthrough of the dynamic self-mixing technology of the oil extraction and water injection device.

[0041] Referring to Figure 6, the first through groove 103 is annularly arranged on the inner wall of the reduced-diameter cavity 102, the inner diameter of the communication part between the mixing cavity 101 and the reduced-diameter cavity 102 gradually reduces from top to bottom, and the reduced-diameter cavity 102 extends into the long tube 901 and is spliced with the inner flow tube 903.

[0042] In the embodiment, it needs to be particularly pointed out that: the first through groove 103 is annularly arranged on the inner wall of the reduced-diameter cavity 102, for example, 8-12 through channels are arranged at equal angles along the circumference, so that the fluid in the mixing cavity 101 uniformly flows out from the circumference of the reduced-diameter cavity 102, avoiding the flow deviation or local flow unevenness of the fluid caused by a single outlet, and ensuring the flow field stability when entering the long tube 901; the multiple through channels in the annular array divide the fluid into multiple streams, each stream locally accelerates when passing through the through channel, forms a shear force, and further breaks the mixed liquid into smaller particles, and cooperates with the spiral structure of the subsequent self-mixing mechanism 9, so that the uniformity of mixing can be improved by about 10%; the reduced-diameter cavity 102 is spliced with the inner flow tube 903, the smooth transition of the fluid path is realized, the fluid turbulence or energy loss caused by the structural mutation can be avoided, the smooth flow of the fluid from the reduced-diameter cavity 102 to the long tube 901 is ensured, and the high flow rate state is maintained to strengthen the mixing.

[0043] Working principle of the application: The main problem solved by the embodiment is that: the scheme mixes the medicine water in the flow by using the dosing mechanism 8 and the self-mixing mechanism 9, solves the problems of low efficiency caused by the need for stirring of the medicine water, and uneven and low efficiency of self-mixing; and a multi-channel switchable fluid control structure is designed, three modes can be flexibly adapted by valve switching, and the problems of fixed process of the existing water injection device, inability to adapt to different medicine characteristics, high process energy consumption and poor flexibility are solved.

[0044] The specific steps are as follows: S1, direct filtration water injection mode: It is suitable for no need to add medicine, the fifth valve 601 and the third valve 402 are opened, and the first valve 301, the fourth valve 501, the second valve 401 and the sixth valve 701 are closed, the water flow path is: water inlet pipe 3→second auxiliary pipeline 6→filter 2→water outlet pipe 4, and then the water is directly injected; S2, filtration and then dosing mode: It is suitable for medicine water such as bactericide which needs to be dosed after filtration, the fifth valve 601, the fourth valve 501 and the second valve 401 are opened, and the first valve 301, the third valve 402 and the sixth valve 701 are closed; the water flow path is: water inlet pipe 3→second auxiliary pipeline 6→filter 2→first auxiliary pipeline 5→mixing cavity 101 of mixing tank 1→dosing mechanism 8 adding medicine water→reduced-diameter cavity 102→self-mixing mechanism 9 mixing→water outlet pipe 4, and then the water is directly injected; S3, dosing and then filtration mode: The medicine water such as flocculant which needs to be added after filtering is suitable, the first valve 301, the sixth valve 701 and the third valve 402 are opened, and the fifth valve 601, the fourth valve 501 and the second valve 401 are closed;Water flow path: water inlet pipe 3→mixing cavity 101 of mixing tank 1→medicine water adding mechanism 8 adds medicine water→diameter reducing cavity 102→mixing from mixing mechanism 9→water outlet pipe 4→third auxiliary pipeline 7→filter 2→water outlet pipe 4, then directly water injection.

[0045] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A water injection device for an oil wellhead, comprising a mixing tank (1), characterized in that: The water inlet of the mixing tank (1) is connected to a water inlet pipe (3) and a first auxiliary pipe (5). A mixing chamber (101) and a reduced diameter chamber (102) are provided in the mixing tank (1) from top to bottom. A conical bucket (11) is fixedly connected to the mixing chamber (101). A plurality of first through grooves (103) are provided on the inner wall of the reduced diameter chamber (102). The water inlet pipe (3) is connected to the water inlet of the filter (2) through the second auxiliary pipe (6). The other end of the first auxiliary pipe (5) is connected to the water inlet of the filter (2). The mixing tank (1) is connected to the water outlet of the filter (2), the water outlet of the filter (2) is connected to a water outlet pipe (4), the water outlet pipe (4) is connected to the water inlet of the filter (2) through a third auxiliary pipe (7), and a dosing mechanism (8) and a self-mixing mechanism (9) are provided on the mixing tank (1). The medicine is added to the mixing chamber (101) through the dosing mechanism (8), and then the medicine is assisted by the self-mixing mechanism (9) and connected to the water outlet pipe (4) to achieve self-mixing of the medicine during flow. The self-mixing mechanism (9) comprises a long tube (901), an inner flow tube (903) and an outlet tube (906); the long tube (901) is fixedly connected to the bottom of the mixing tank (1); the reduced diameter cavity (102) is located in the long tube (901); an inner thread strip (902) is provided inside the long tube (901); the inner flow tube (903) is fixedly connected to the lower inner wall of the long tube (901); a second through groove (905) and an outer thread strip (904) are provided on the circumferential surface of the inner flow tube (903); and the outlet tube (906) is provided at the lower end of the long tube (901) and is connected to the water outlet pipe (4).

2. The water injection device for an oil wellhead according to claim 1, characterized in that: The dosing mechanism (8) comprises an annular tube (801) and an atomizing nozzle (804). The annular tube (801) is located on the upper side of the mixing tank (1). The annular tube (801) injects liquid medicine through the medicine inlet pipe (802). A plurality of atomizing nozzles (804) are provided and are evenly distributed on the top of the mixing tank (1). The annular tube (801) is connected to the plurality of atomizing nozzles (804) through a diverter pipe (803), thereby evenly injecting liquid medicine into the mixing chamber (101).

3. The water injection device for an oil wellhead according to claim 2, characterized in that: The conical bucket (11) has a mesh structure, and a 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 0.5-2 mm. The mesh structure is woven with stainless steel wire, and the surface of the wire is provided with an anti-rust coating.

4. The water injection device for an oil wellhead according to claim 3, characterized in that: 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).

5. The water injection device for an oil wellhead according to claim 4, characterized in that: The water outlet pipe (4) is provided with a second valve (401) and a third valve (402), the third valve (402) being located between the water outlet pipe (4) and the water outlet of the filter (2), a sixth valve (701) being provided between the water outlet pipe (4) and the third auxiliary pipe (7), and the second valve (401) being located between the third valve (402) and the sixth valve (701).

6. The water injection device for an oil wellhead according to claim 5, characterized in that: The internal thread strip (902) extends spirally along the inner wall of the long tube (901), and the external thread strip (904) extends spirally along the surface of the inner flow tube (903), and the spiral directions of the internal thread strip (902) and the external thread strip (904) are the same.

7. The water injection device for an oil wellhead according to claim 6, characterized in that: The first through grooves (103) are distributed in a circular array on the inner wall of the diameter-reducing cavity (102); the inner diameter of the connection point between the mixing cavity (101) and the diameter-reducing cavity (102) gradually decreases from top to bottom, and the diameter-reducing cavity (102) extends into the long tube (901) and is spliced ​​with the inner flow tube (903).

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