Hollow sucker rod thermal washing check valve for oil field

Abstract

The utility model discloses a hollow sucker rod thermal washing check valve for an oil field, which comprises an upper joint, a lower working barrel and a thermal washing liquid nozzle, the thermal washing liquid nozzle is arranged above a partition table in the lower working barrel, and a thrust spring and a plunger are also arranged in an inner cavity above the partition table; the upper joint is connected with a lower working barrel provided with a thrust spring and a plunger; before hot washing liquid enters the hot washing check valve, the plunger seals the hot washing liquid nozzle. The utility model can be applied to a low-pressure and low-yield oil well, effectively improves the paraffin precipitation problem, and has the advantages of reasonable design, simple structure and no welding piece. The elastic force of the thrust spring and the plunger are used for blocking the hot washing liquid nozzle, and oil in an oil pipe is prevented from entering the hollow rod column in the well descending process of the device. The hot washing efficiency and the hot washing effect are effectively improved, the daily maintenance workload of oil well paraffin removal is reduced, paraffin precipitation and production accidents caused by paraffin precipitation are prevented, the production cost can be effectively reduced, and economic benefits are improved.

Description

Technical Field

[0001] This utility model relates to a hot washing and dewaxing device for hollow sucker rods used in oil fields, and in particular a vortex-type hot washing single-flow valve for hollow sucker rods. Background Technology

[0002] Hot washing is the main measure for removing wax from oil wells during the oilfield extraction process. With the promotion and use of hot washing technology for hollow sucker rods, the problem of wax buildup on hollow sucker rods that are lowered into the oil well to a depth of 500-800 meters has been solved.

[0003] Current hollow sucker rod hot washing technology typically involves injecting hot washing fluid into the hollow rod string, which is then returned from the bottom-of-well check valve. This fluid, along with the well fluid inside the wellbore, flows through the annular space formed between the tubing and the hollow sucker rod string and is discharged from the wellhead. This circulation process achieves the purpose of hot washing and dewaxing. Because this hollow rod hot washing technology has a short washing time, uses less hot washing fluid, and has a fast return time, it significantly reduces the labor intensity of workers and has therefore been widely adopted.

[0004] However, with the long-term development of the oilfield, the number of low-pressure and low-production oil wells has gradually increased. Applying this technology to these wells has not effectively improved the wax deposition problem. The main reason is that during implementation, issues such as bottom check valve leakage, hollow rod blockage, hollow rod sealing ring punctures, and inability to perform hot washing frequently occur, resulting in a significant waste of manpower and resources and increasing production costs.

[0005] Currently, the main reason for the failure is the unreasonable structure of the check valves used. Due to structural problems such as the welding process employed in the check valves, jamming and poor sealing are prone to occur. When the check valve fails, the original well fluid backflows into the inner cavity of the hollow sucker rod, causing blockage and ultimately leading to the failure of the hollow sucker rod string.

[0006] After searching, the following related patent technologies are currently available: The hollow sucker rod hot washing and dewaxing device disclosed in patent application number CN200720169702.8 is a hollow sucker rod hot washing and dewaxing device used in oilfield development. It includes a hot washing tee, a hot washing check valve, a hollow rod, tubing, and a hot washing screen. The hot washing tee, hot washing check valve, and hot washing check valve are connected in sequence. The hollow rod and the solid rod are connected by a hot washing screen. It uses the hollow sucker rod as the hot washing injection channel and the annulus of the rod as the return channel, and ensures that the hot washing medium does not pass through the pump, but only circulates between the hollow rod and the tubing on the pump.

[0007] However, the above-mentioned device still has the following defects: the above-mentioned device is mainly an improvement on the hot washing and dewaxing device for hollow sucker rods, but it has not made any substantial changes to the hot washing check valve. Moreover, the structure is complex and the installation process is cumbersome. Due to the use of two check valves, the check valves are prone to not sealing properly.

[0008] Patent application CN202110396034.7 discloses a hot washing valve for hollow rod wells in oil pumping units, specifically relating to the technical field of hot washing valves for hollow rods in oil pumping units. The technical solution includes a connecting device and a long rod, with the connecting device located at both ends of the long rod. It also includes a flow-stopping device disposed on the inner wall of the long rod, and a flow-diverting device disposed on the inner wall of the long rod. The flow-stopping device includes a sliding groove and a ball; the sliding groove is located at the middle of the inner wall of the long rod, and the ball is inserted into the bottom end of the inner wall of the sliding groove. The flow-diverting device includes a first inlet groove and a second inlet groove; the first inlet groove is located at the top of the inner wall of the long rod, and the second inlet groove is located at the bottom end of the inner wall of the long rod. The bottom end of the first inlet groove is connected to the second inlet groove. The connecting device includes a first female connector and a second female connector; the first female connector is located at the top of the long rod. The beneficial effects of the above invention are: by using the above invention, not only will hot water contamination be avoided, but the well washing time and well washing efficiency will also be improved.

[0009] However, the above invention still has the following defects: the structure of the hot washing valve for hollow rod wells of this type of pumping unit is complex, the sealing performance between the ball and the ball seat is poor, and after the one-way valve fails, it is easy to cause blockage in the inner cavity of the hollow rod. Since no overflow prevention measures are taken for the hot washing fluid, it is easy to cause pollution to the oil layer below the hot washing valve.

[0010] Patent application CN201020175846.6 discloses a hollow sucker rod hot-washing and wax-removing bottom-hole check valve, applied to oil well hot wax removal, enabling hot-washing and wax removal through a hollow sucker rod. An upper connecting body is connected to the lower end of an upper connector. The upper connecting body has symmetrical axial through holes on both sides of the central hole at its lower end, and a transverse hole that communicates with the upper end of the central hole. An intermediate connecting body is connected to the outer wall of the upper connecting body, and a valve core assembly is located within the central hole cavity at its upper end. A lower connecting pipe is connected to the outer wall of the intermediate connecting body, and the valve core assembly is located within the central hole cavity at its upper end. A lower connector is connected to the lower end of the lower connecting pipe. The advantages are: enabling hot-washing and wax removal through a hollow sucker rod, improving the sealing performance of the check valve; increasing the flow channel size to meet the stress requirements of the hollow sucker rod hot-washing and wax-removing bottom-hole check valve, thus improving the reliability of the bottom-hole check valve.

[0011] However, the following defects still exist: This type of hollow sucker rod hot washing and wax removal bottom-hole one-way valve uses a ball valve and ball seat combination method. Under harsh working conditions in the well, the ball valve and ball seat are prone to jamming, poor sealing, etc. The flow channel is small and easy to be blocked, and the spring is prone to corrosion and failure.

[0012] The hot washing and dewaxing device for hollow sucker rods still needs improvement. Summary of the Invention

[0013] The purpose of this invention is to provide a hot-washing check valve for hollow sucker rods in oilfields, specifically a check valve for hot-washing and dewaxing hollow sucker rods in rod-pumped oil wells. This improves the structure of current hot-washing check valves, reducing and avoiding problems such as blockage and leakage in hollow sucker rods. It also reduces the occurrence of bottomhole contamination accidents, improves the effectiveness and efficiency of hot-washing and dewaxing, reduces waste of manpower and resources in the process, lowers production costs, and improves economic benefits.

[0014] To achieve the above objectives, the technical solution of this utility model is: a hot wash one-way valve for hollow sucker rods in oil fields, comprising an upper connector, a lower working cylinder, and a hot wash fluid nozzle, wherein: the hot wash fluid nozzle is located above a partition in the lower working cylinder, and a thrust spring and a plunger are also installed in the inner cavity above the partition; the upper connector is connected to the lower working cylinder, which is equipped with the thrust spring and the plunger; before the hot wash fluid enters the hot wash one-way valve, the plunger seals the hot wash fluid nozzle.

[0015] Preferably, the lower working cylinder has a stepped inner cavity and is provided with an upper cavity, a middle cavity, and a lower cavity. The upper cavity is connected to the middle cavity, and the inner diameter of the upper cavity is larger than that of the middle cavity. Both the upper cavity and the lower cavity are provided with internal threads. The internal thread in the upper cavity is connected to the upper connector thread, and the internal thread in the lower cavity is connected to the lower end of the hollow sucker rod. The hot washing fluid nozzle is located in the cylinder wall of the middle cavity.

[0016] Preferably, the central cavity has three or more hot washing liquid nozzles in its cylindrical wall, and the hot washing liquid nozzles are evenly distributed in the central cavity and located at the top of the central cavity.

[0017] Preferably, the hot washing liquid nozzle has three upward-sloping spiral holes, and the upward angle between the axis of the hot washing liquid nozzle and the axis of the lower working cylinder is 30°.

[0018] Preferably, the plunger is a non-uniform diameter cylinder with the upper cylinder being larger than the lower cylinder, and the top of the plunger is an upward-facing arc-shaped plunger sealing surface; the outer surface of the plunger and the inner circle of the middle cavity are both precision-machined surfaces.

[0019] Preferably, the inner diameter of the upper connector is smaller than the maximum outer diameter of the plunger; the inner edge of the bottom of the inner cavity of the upper connector is provided with a downward-facing, arc-shaped upper connector sealing surface, which mates with the plunger sealing surface of the plunger.

[0020] Preferably, the lower cylinder of the plunger can be inserted into the thrust spring, and the gap between the outer diameter of the lower cylinder of the plunger and the inner diameter of the thrust spring is set between 0.5mm and 1mm.

[0021] Preferably, the thrust spring is made of alloy spring steel, and the thrust spring and the middle cavity of the lower working cylinder are in clearance fit.

[0022] Preferably, there is a gap of 0.5mm-1mm between the outer diameter of the thrust spring and the inner diameter of the middle cavity of the lower working cylinder; the spring pressure of the thrust spring is set between 1.0MPa and 1.5MPa.

[0023] Preferably, the middle cavity of the lower working cylinder is filled with hydraulic oil, and the amount of hydraulic oil injected is set between 1 / 2 and 2 / 3 of the height of the middle cavity.

[0024] Compared with the prior art, the significant effects of this utility model are as follows: This utility model can be applied to low-pressure, low-production oil wells, effectively improving the wax deposition problem. This utility model has a reasonable design and simple structure, with no welded parts. The lower working cylinder has a partition in its inner cavity, making the lower cavity of the lower working cylinder an independent cavity.

[0025] This invention utilizes the elasticity of a thrust spring and a plunger to seal the hot washing fluid nozzle, preventing oil from entering the hollow rod column during the well running process of this device.

[0026] During the connection between the lower working barrel and the upper connector, the plunger installed inside the lower working barrel is pressed down by the upper connector and gradually seals the hot washing fluid nozzle. Once the upper connector is fully installed, the hot washing fluid nozzle is completely sealed. The plunger seals the hot washing fluid nozzle during the well run, preventing oil from entering the hollow rod column from the hot washing fluid nozzle.

[0027] Because this invention does not use welded components, its structure is more stable. The lower working cylinder only contains a thrust spring and a plunger, resulting in less resistance to the hot washing fluid flow. As an auxiliary device for hot washing of hollow rods, this invention effectively prevents accidents such as hollow rod blockage and environmental pollution caused by well fluid erosion and mechanical failures. It effectively improves hot washing efficiency and effect, and reduces the daily maintenance workload for oil well dewaxing. It significantly increases the operating rate of oil production equipment, prevents wax buildup and related production accidents, effectively reduces production costs, and improves economic benefits.

[0028] This invention features three or more hot washing fluid nozzles arranged in a spiral pattern and evenly distributed. The nozzles are spirally inclined upwards, with the nozzle axis forming a 30° angle with the axis of the lower working cylinder. Compared to existing single-flow hot washing valves with only one outlet, this design offers a larger fluid flow channel, significantly improving the hot washing effect. Specifically, when the hot washing fluid is ejected from the nozzles, it forms a high-speed rotating flow. Under centrifugal force, this flow creates a hollow channel along the central area of ​​the device. The hot washing fluid, carrying dissolved wax and solid particles, accelerates and exits from the wellhead. This device can be lowered 500-800 meters into the well with the hollow sucker rod string, achieving swirling pressurization during hot washing. This reduces the likelihood of jamming and failure, minimizes wellbore contamination accidents, and reduces losses of manpower, resources, and equipment. It also improves the success rate and efficiency of hot washing for wax removal. Furthermore, it protects the environment, reduces the labor intensity of operators, and enhances economic benefits.

[0029] This invention features precision machining and polishing of the plunger's outer surface and the central cavity in the lower working cylinder, improving the sealing performance between the upper connector and the central cavity in the lower working cylinder, thus forming an effective seal. The upper connector's sealing surface mates with the plunger's sealing surface, enhancing the sealing performance of this one-way valve, further reducing the likelihood of jamming and failure, and significantly improving the success rate of hot cleaning and wax removal. It demonstrates significant effectiveness and application value.

[0030] This invention optimizes the spring specific pressure of the thrust spring, setting it between 1.0MPa and 1.5MPa to make the operation more stable.

[0031] In this invention, hydraulic oil is injected, and the amount of hydraulic oil injected is set between 1 / 2 and 2 / 3 of the height of the central cavity. This avoids excessive pressure in the central cavity during the plunger's downward pressing process, while ensuring that the thrust spring has good lubrication and corrosion protection.

[0032] This invention ensures excellent sealing performance during the hot washing process of the hollow sucker rod string. The upper connector and plunger employ a plunger-type design, and the sealing surface between them uses a spherical seal, increasing the sealing area and making opening and closing more stable. The thrust spring, housed in the central cavity, is immersed in hydraulic oil, enhancing corrosion resistance and lubrication while ensuring it remains in optimal working condition.

[0033] In summary, this utility model has a reasonable structure, significant effects, and great value for promotion and application. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a structural analytical diagram of the present invention.

[0036] Figure 2 yes Figure 1 A schematic diagram of the upper and middle joint.

[0037] Figure 3 yes Figure 1 A schematic diagram of the structure of the lower middle working cylinder.

[0038] Figure 4 yes Figure 1 A schematic diagram of the middle plunger.

[0039] Figure 5 This is a schematic diagram showing the lower working cylinder after the thrust spring and plunger have been installed.

[0040] In the diagram: Upper connector 1, external thread 1-1, upper connector sealing surface 1-2; plunger 2, plunger sealing surface 2-1; thrust spring 3; lower working cylinder 4, internal thread 4-1, hot washing liquid nozzle 4-2, upper cavity 4-3, middle cavity 4-4, lower cavity 4-5, partition 4-6; hydraulic oil 5. Detailed Implementation

[0041] The accompanying drawings are for reference and illustration only and are not intended to limit the scope of protection of this utility model. The technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0042] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0043] In the description of this utility model, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, in the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] See Figures 1 to 5 A hot wash one-way valve for hollow sucker rods used in oilfields includes an upper connector 1, a lower working cylinder 4, and a hot wash fluid nozzle 4-2. The hot wash fluid nozzle 4-2 is located above a partition 4-6 in the lower working cylinder 4, and a thrust spring 3 and a plunger 2 are also installed in the inner cavity above the partition 4-6. The upper connector 1 is connected to the lower working cylinder 4, which is equipped with the thrust spring 3 and the plunger 2. Before the hot wash fluid enters the hot wash one-way valve, the plunger 2 seals the hot wash fluid nozzle 4-2.

[0045] This utility model has a reasonable design and simple structure, with no welded parts. A partition 4-6 is provided inside the lower working cylinder 4, making the lower cavity of the lower working cylinder 4 an independent cavity. This utility model utilizes the elasticity of the thrust spring 3 and the plunger 2 to seal the hot washing fluid nozzle 4-2, preventing oil from the tubing from entering the hollow rod string during the well-running process. This utility model is connected to the lower end of the hollow sucker rod string and is lowered into the well along with the hollow sucker rod string.

[0046] During the connection process between the lower working barrel 4 and the upper connector 1, the plunger 2 installed inside the lower working barrel 4 is pressed down by the upper connector 1 and gradually seals the hot washing fluid nozzle 4-2. When the upper connector 1 is fully installed, the hot washing fluid nozzle 4-2 is completely sealed. The plunger 2 seals the hot washing fluid nozzle 4-2 during the well running process, preventing the oil in the tubing from entering the hollow rod column from the hot washing fluid nozzle 4-2.

[0047] Because this invention does not use welded components, its structure is more stable. The lower working cylinder 4 only contains a thrust spring 3 and a plunger 2, resulting in less resistance to the hot washing fluid flow. As an auxiliary device for hot washing of hollow rods, this invention effectively prevents accidents such as hollow rod blockage and environmental pollution caused by well fluid erosion and mechanical failures. It effectively improves hot washing efficiency and effect, and reduces the daily maintenance workload for oil well dewaxing. It significantly increases the operating rate of oil production equipment, prevents wax buildup and related production accidents, effectively reduces production costs, and improves economic benefits.

[0048] Based on the above embodiment one, the present invention also has the following embodiments: A preferred embodiment: The lower working cylinder 4 has a stepped inner cavity and is provided with an upper cavity 4-3, a middle cavity 4-4 and a lower cavity 4-5. The upper cavity 4-3 is connected to the middle cavity 4-4 and the inner diameter of the upper cavity 4-3 is larger than the inner diameter of the middle cavity 4-4. Both the upper cavity 4-3 and the lower cavity 4-5 are provided with internal threads 4-1. The internal thread 4-1 in the upper cavity 4-3 is threadedly connected to the upper connector 1, and the internal thread 4-1 in the lower cavity 4-5 is connected to the lower end of the hollow sucker rod. The hot washing liquid nozzle 4-2 is disposed in the cylinder wall of the middle cavity 4-4.

[0049] In a preferred embodiment, the central cavity 4-4 has three or more hot cleaning fluid nozzles 4-2, which are evenly distributed within the wall of the central cavity 4-4 and located at the top of the cavity. In this invention, the hot cleaning fluid nozzles 4-2 are three or more, evenly distributed, and positioned at the top of the central cavity 4-4. When the hot cleaning fluid enters the device from the hollow sucker rod string, it first presses down the plunger 2, exposing the hot cleaning fluid nozzles 4-2. The hot cleaning fluid then enters the annulus between the tubing and the hollow sucker rod string from the hot cleaning fluid nozzles 4-2, circulating and cleaning the dirt and wax deposits therein.

[0050] In a preferred embodiment, the hot washing fluid nozzle 4-2 has three upwardly inclined spiral holes, and the upward angle between the axis of the hot washing fluid nozzle 4-2 and the axis of the lower working cylinder 4 is 30°. In this invention, there are three or more hot washing fluid nozzles 4-2, which are spirally inclined and evenly distributed. The hot washing fluid nozzles 4-2 are spirally inclined holes, and the upward angle between the axis of the nozzle and the axis of the lower working cylinder 4 is 30°. Compared with the existing hot washing single-flow valve which has only one outlet, its fluid flow channel size is larger, which can significantly improve the hot washing effect. Specifically, when the hot washing fluid is sprayed from the hot washing fluid nozzle 4-2, it can form a high-speed rotating fluid flow. Under the action of centrifugal force, the fluid flow forms a hollow channel along the central area of ​​the device. The hot washing fluid, carrying dissolved wax and solid particles, is accelerated and discharged from the wellhead. This device can be lowered 500-800 meters into the well along with the hollow sucker rod string, achieving vortex pressurization during hot washing. This reduces the likelihood of the device jamming or failing, minimizes wellbore contamination accidents, and reduces losses of manpower, resources, and equipment. It also improves the success rate and efficiency of hot washing for dewaxing. Furthermore, it protects the environment, reduces the workload of operators, and enhances economic benefits.

[0051] In a preferred embodiment: the plunger 2 is a non-uniform diameter cylinder with the upper cylinder larger than the lower cylinder, and the top of the plunger 2 is an upward-facing arc-shaped plunger sealing surface 2-1; the outer surface of the plunger 2 and the inner circle of the middle cavity 4-4 are both precision-machined surfaces. Precision machining and polishing of the outer surface of the plunger 2 and the middle cavity 4-4 improve the sealing performance between the plunger 2 and the contact surfaces with the upper connector 1 and the middle cavity 4-4 of the lower working cylinder 4, forming an effective seal.

[0052] In a preferred embodiment, the inner diameter of the upper connector 1 is smaller than the maximum outer diameter of the plunger 2; the inner bottom edge of the inner cavity of the upper connector 1 is provided with a downward-facing, arc-shaped upper connector sealing surface 1-2, which mates with the plunger sealing surface 2-1 of the plunger 2. This increases the sealing performance of the check valve, further reduces the likelihood of jamming and failure, significantly improves the success rate of hot cleaning and wax removal, and has significant practical effects and application value.

[0053] In a preferred embodiment, the lower cylinder of the plunger 2 can be inserted into the thrust spring 3, and the gap between the outer diameter of the lower cylinder of the plunger 2 and the inner diameter of the thrust spring 3 is set between 0.5mm and 1mm.

[0054] In a preferred embodiment, the thrust spring 3 is made of alloy spring steel, and the thrust spring 3 and the middle cavity 4-4 of the lower working cylinder 4 are in clearance fit.

[0055] In a preferred embodiment: a gap of 0.5mm-1mm is provided between the outer diameter of the thrust spring 3 and the inner diameter of the middle cavity 4-4 of the lower working cylinder 4; the spring pressure of the thrust spring 3 is set between 1.0MPa and 1.5MPa.

[0056] In a preferred embodiment, hydraulic oil 5 is injected into the middle cavity 4-4 of the lower working cylinder 4. The injection volume of hydraulic oil 5 is set between 1 / 2 and 2 / 3 of the height of the middle cavity 4-4. This avoids excessive pressure in the middle cavity 4-4 during the downward pressing of the plunger 2, while ensuring that the thrust spring 3 has good lubrication and corrosion protection.

[0057] This invention ensures excellent sealing performance during the hot washing process of the hollow sucker rod string. The upper connector 1 and plunger 2 employ a plunger-type design, and the sealing surfaces between them utilize spherical seals, increasing the sealing surface area and making opening and closing more stable. The outer surface of the plunger 2 and the inner wall of the central cavity 4-4 in the lower working cylinder 4 are precision-machined, enhancing the sealing effect. The thrust spring 3, installed inside the central cavity 4-4, is immersed in hydraulic oil 5, enhancing corrosion resistance and lubrication while ensuring it remains in optimal working condition.

[0058] The embodiments described above are merely typical examples, but the present invention is not limited to these embodiments. Those skilled in the art can make modifications without departing from the spirit and teachings of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the inventive spirit and concept of the present invention should be included within the protection scope of the present invention. Therefore, the protection scope is not limited to the above description.

Claims

1. A hollow sucker rod hot wash check valve for oil fields, comprising an upper joint, a lower working cylinder and a hot wash liquid nozzle, characterized in that: The hot wash liquid nozzle is arranged above the partition in the lower working cylinder, and the thrust spring and the plunger are also installed in the inner cavity above the partition; the upper joint is connected to the lower working cylinder where the thrust spring and the plunger are installed; before the hot wash liquid enters the hot wash check valve, the plunger seals the hot wash liquid nozzle.

2. The hollow sucker rod hot wash check valve for oil fields as claimed in claim 1, characterized in that: The lower working cylinder is a stepped inner cavity and is provided with an upper cavity, a middle cavity and a lower cavity. The upper cavity is connected to the middle cavity and the inner diameter of the upper cavity is larger than the inner diameter of the middle cavity. Both the upper cavity and the lower cavity are provided with internal threads. The internal threads in the upper cavity are connected to the upper joint threads, and the internal threads in the lower cavity are connected to the lower end of the hollow sucker rod column. The hot wash liquid nozzle is arranged in the cylinder wall of the middle cavity.

3. The hollow sucker rod hot wash check valve for oil fields as claimed in claim 2, characterized in that: More than three hot washing liquid nozzles are arranged in the cylinder wall of the middle cavity, and the hot washing liquid nozzles are evenly distributed in the cylinder wall of the middle cavity and are located at the top of the cavity of the middle cavity.

4. A hollow sucker rod hot wash check valve for oil fields as claimed in claim 1, 2 or 3, characterized in that: The hot wash liquid nozzle is provided with three upwardly inclined spiral holes, and the upward angle between the axis of the hot wash liquid nozzle and the axis of the lower working cylinder is 30°.

5. The hollow sucker rod hot wash check valve for oil fields as claimed in claim 4, characterized in that: The plunger is a non-uniform cylinder, the upper cylinder is larger than the lower cylinder, and the top of the plunger is an upward arc-shaped plunger sealing surface; the outer surface of the plunger and the inner circle of the middle cavity are both precision-machined surfaces.

6. The hollow sucker rod hot wash check valve for oil fields as claimed in claim 5, characterized in that: The inner diameter of the upper joint is smaller than the maximum outer diameter of the plunger; a downward arc-shaped upper joint sealing surface is provided on the inner edge of the inner cavity bottom of the upper joint, and the upper joint sealing surface matches the plunger sealing surface of the plunger.

7. The hollow sucker rod hot wash check valve for oil fields as claimed in claim 6, characterized in that: The lower cylinder of the plunger can be inserted into the thrust spring, and the gap between the outer diameter of the lower cylinder of the plunger and the inner diameter of the thrust spring is set between 0.5mm-1mm.

8. The hollow sucker rod hot wash check valve for oil fields as claimed in claim 7, characterized in that: The thrust spring is made of alloy spring steel, and there is a clearance fit between the thrust spring and the middle cavity of the lower working cylinder.

9. The hollow sucker rod hot wash check valve for oil fields as claimed in claim 8, characterized in that: A gap of 0.5mm-1mm is provided between the outer diameter of the thrust spring and the inner diameter of the middle cavity of the lower working cylinder; and the spring pressure ratio of the thrust spring is set between 1.0MPa-1.5MPa.

10. A hollow sucker rod hot wash check valve for oil fields as claimed in claim 9, characterized in that: The middle cavity of the lower working cylinder is filled with hydraulic oil, and the injection amount of the hydraulic oil is set between 1 / 2 and 2 / 3 of the height of the middle cavity.

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