Gas-proof pipe column suitable for carbon dioxide gas channeling high-gas-liquid-ratio oil well

Abstract

The high-gas-liquid-ratio oil well anti-gas pipe column comprises a gravity separation barrel, an inner pipe is coaxially arranged in an inner cavity of the gravity separation barrel, and a plurality of gravity cups are arranged on the outer wall above the middle of the gravity separation barrel in a sleeved mode. A plurality of gravity separation liquid inlet holes are uniformly distributed in the circumference of the gravity separation cylinder close to the bottom wall of each gravity cup, the upper end of the gravity separation cylinder is rotationally connected with a first-stage exhaust valve body through a middle hoop, and the upper end of an inner pipe is rotationally connected and communicated with the lower end of a center hole of the first-stage exhaust valve body; first-stage axial valve holes which are axially through are symmetrically formed in the periphery of a center hole of the first-stage exhaust valve body, a first-stage valve ball is arranged in a horn mouth in the lower end of each first-stage axial valve hole, a plug cap is connected to an upper port of each first-stage axial valve hole in a screwed mode, and a first-stage exhaust channel which is outwards through in the radial direction is formed in the side wall of each first-stage axial valve hole. The anti-gas pipe column can eliminate or reduce gas entering a pump under the condition of high gas-liquid ratio after oil well gas channeling, and the oil well pump efficiency is improved.

Description

Technical Field

[0001] The utility model relates to an anti-gas pipe column for oil wells, in particular to an anti-gas pipe column suitable for oil wells with high gas-liquid ratio and carbon dioxide gas channeling. The utility model is suitable for situations where low pump efficiency or "gas lock" is easily generated due to pump air intake during the production process of the oil well with high gas-liquid ratio, and belongs to the technical field of carbon dioxide drive oil production. Background Art

[0002] Carbon dioxide flooding is currently the most efficient development model for low-permeability reservoirs, and can achieve twice the output of conventional technologies for a single oil well. However, as production progresses, the blowout of injected gas caused by the continuous injection of carbon dioxide will lead to a large amount of gas in the oil production process. During the pumping process, both gas and liquid phases enter the pump cavity at the same time. The gas entering the pump cavity will inevitably reduce the amount of liquid entering the pump cavity, thereby reducing the filling coefficient of the entire oil pump and the pump efficiency of the oil pump. When the gas impact is serious, even "gas lock" and other phenomena may occur.

[0003] In the actual production process, it is often used to install gas-liquid separation devices under the pump, that is, various gas anchors, to achieve gas-liquid separation of the mixed phase, discharge the gas into the casing annulus, thereby eliminating or reducing the gas entering the pump and improving the pump efficiency. The principle of conventional gravity gas anchors is to use the gravity difference generated by oil and gas with different densities to separate the mixed phase. The advantage of this gas anchor is that the separation action is simple and reliable, and the disadvantage is that the separation capacity is greatly limited by the length and diameter of the gas anchor, and it cannot be applied to oil wells with high gas-oil ratio, large well deviation, and small wellbore.

[0004] The principle of conventional spiral gas anchor is to use the different centrifugal effects produced by oil and gas with different densities in the spiral flow channel to separate the mixed phase. The separation effect of the gas anchor depends on the mixed phase velocity in the gas anchor. The higher the mixed phase velocity, the smaller the bubbles dissolved in the liquid phase can be separated. The advantage of this gas anchor is that it has high gas separation efficiency and is suitable for production wells with high liquid production and high gas-liquid ratio. The disadvantage is that it cannot be applied to low-yield wells with high gas-oil ratio.

[0005] The Chinese utility model patent with the publication number CN209704543U discloses a wellbore gas prevention and control pipe column, including a pipe sleeve, an oil pipe is installed in the pipe sleeve, an anti-back pressure oil pump is installed in the oil pipe, and an inner cover type gas prevention device is installed at the end of the anti-back pressure oil pump; wherein, the anti-back pressure oil pump includes a pump barrel and a plunger installed in the pump barrel, a sucker rod is installed in the pipe sleeve, and the sucker rod is connected to the plunger in the anti-back pressure oil pump; the inner cover type gas prevention device includes an exhaust pipe, a center pipe is arranged in the exhaust pipe, and an annulus cavity is formed between the exhaust pipe and the center pipe; a centrifugal separator is installed at the upper end of the exhaust pipe, a wire plug is installed at the lower end of the exhaust pipe, and a liquid inlet is opened on the exhaust pipe, and the liquid inlet is connected to the annulus cavity. The inner cover type gas prevention device in this technical solution only uses density difference to separate the produced liquid and gas, and the separation efficiency is not high.

[0006] The Chinese utility model patent with the publication number CN209908465U discloses a multifunctional anti-gas and anti-sand oil production combined tool, which is provided with a centrifugal separation device, which is provided with an outer tube; the outer tube is connected to the pipeline at the lower end of the lower coupling through an upper joint, the outer tube is provided with a gas escape port at the upper joint end, the outer tube is provided with a mixture inlet at the lower part of the gas escape port, and the lower end of the outer tube is connected to the sand settling tail pipe through a lower joint; the inner tube is placed inside the outer tube and forms a cavity with the outer tube to accommodate the mixture, the upper end of the inner tube is fixedly connected to the upper joint, a liquid channel for the circulation of liquid objects is formed inside the inner tube, and a plurality of laser slits connected to the liquid channel are arranged on the side wall of the inner tube to isolate solid substances and allow liquid substances to flow into the liquid channel. This technical solution increases the separation force of gaseous substances through the centrifugal action of the gas-liquid spiral blades, so that the gaseous substances are separated in the gas-liquid section of the inner tube and discharged into the air of the oil sleeve ring through the gas escape port. In the case of high gas-liquid ratio, the separation efficiency is not enough and gas lock phenomenon still occurs.

[0007] In summary, in order to eliminate or reduce the gas entering the pump under high gas-liquid ratio conditions after carbon dioxide gas breakthrough in oil wells and improve the pump efficiency of oil wells, it is of great significance to study and design a multi-stage gas-liquid separator suitable for high gas-liquid ratio downhole. Utility Model Content

[0008] The utility model aims to provide a gas prevention pipe column suitable for carbon dioxide gas breakthrough in high gas-liquid ratio oil wells, which can eliminate or reduce the gas entering the pump under high gas-liquid ratio conditions after carbon dioxide gas breakthrough in the oil wells, thereby improving the pump efficiency of the oil wells.

[0009] In order to solve the above technical problems, the utility model is a gas prevention pipe column suitable for carbon dioxide gas breakthrough high gas-liquid ratio oil wells, including a gravity separation cylinder, the inner cavity of the gravity separation cylinder is coaxially provided with an inner tube, the outer wall above the middle of the gravity separation cylinder is sleeved with a plurality of gravity cups, and the circumference of the gravity separation cylinder close to the bottom wall of each gravity cup is evenly distributed with a plurality of gravity separation liquid inlet holes, the upper end of the gravity separation cylinder is screwed with a primary exhaust valve body through a middle coupling, and the upper end of the inner tube is screwed and connected with the lower end of the center hole of the primary exhaust valve body;

[0010] Axially penetrating first-stage axial valve holes are symmetrically arranged on the outer circumference of the central hole of the first-stage exhaust valve body, a first-stage valve ball is respectively placed in the bell mouth at the lower end of each first-stage axial valve hole, a plugging cap is respectively screwed into the upper port of the first-stage axial valve hole, and the side wall of each first-stage axial valve hole is respectively provided with a first-stage exhaust channel penetrating radially outward.

[0011] Furthermore, the upper end of the first-stage exhaust valve body is connected to an outer tube via a reducing coupling, the inner cavity of the outer tube is provided with a double-headed screw, and a plurality of screw air inlet holes are evenly distributed along a spiral line on the circumference of the double-headed screw.

[0012] Furthermore, a special-shaped coupling is screwed onto the upper end of the outer tube, and a secondary exhaust valve is screwed onto the upper end of the double-headed screw.

[0013] Furthermore, a middle partition is provided in the middle of the special-shaped coupling, a recessed special-shaped coupling exhaust chamber is provided below the central area of ​​the middle partition, a coupling radial exhaust hole is provided on the side wall of the special-shaped coupling exhaust chamber, and a plurality of axially penetrating coupling axial liquid outlet holes are also provided on the circumference of the middle partition, and each coupling axial liquid outlet hole is evenly distributed on the outer periphery of the special-shaped coupling exhaust chamber.

[0014] Furthermore, the secondary exhaust valve includes a secondary exhaust valve body, the lower end of the secondary exhaust valve body is screwed to the upper end of the double-headed screw, the upper part of the secondary exhaust valve body is conical and embedded in the special-shaped coupling exhaust chamber, the outer cone surface of the conical head is pressed on the inner cone surface of the lower port of the special-shaped coupling exhaust chamber to close the special-shaped coupling exhaust chamber; a throat is provided in the middle of the central channel of the secondary exhaust valve body, and a bell mouth is provided at the upper end of the throat, in which a secondary valve ball is placed.

[0015] Furthermore, a valve cap is screwed onto the upper end of the central channel of the secondary exhaust valve body, the valve cap is located in the exhaust chamber of the special-shaped coupling, and a valve cap exhaust hole is provided at the top center of the valve cap to communicate with the exhaust chamber of the special-shaped coupling.

[0016] Furthermore, a cyclone separation unit is screwed onto the upper end of the special-shaped coupling, and the cyclone separation unit includes a cyclone separation cylinder. The lower end of the cyclone separation cylinder is screwed onto the upper female thread of the special-shaped coupling, and the lower end inner cavity of the cyclone separation cylinder is provided with a cyclone nozzle for guiding liquid to the inner wall of the cyclone separation cylinder.

[0017] Furthermore, a orifice plate is covered above the middle partition of the special-shaped coupling, the outer edge of the orifice plate is pressed by the lower port of the cyclone separation cylinder, and a plurality of cyclone holes are evenly distributed on the circumference of the orifice plate. The lower port of each cyclone hole is respectively connected to the axial liquid outlet hole of each coupling, and the rotation direction of each cyclone hole is the same as that of the cyclone nozzle.

[0018] Furthermore, a separation body is installed at the upper end of the cyclone separation cylinder, and the center of the lower end of the separation body is further connected. The upper part of the central counterbore at the lower end of the separation body is connected to the annular space around the tool through a cyclone exhaust channel, and the middle part of the central counterbore at the lower end of the separation body is provided with a throat for controlling the cyclone exhaust channel, and a valve ball is provided at the throat.

[0019] Furthermore, the separation body is also provided with a separation body liquid outlet channel which penetrates along the axial direction.

[0020] Furthermore, the cyclone separation unit is provided with two stages in series along the axial direction.

[0021] Furthermore, a tail oil pipe is screwed to the lower end of the gravity separation cylinder, and a threaded plug is screwed to the lower end of the tail oil pipe.

[0022] Compared with the prior art, the utility model has achieved the following beneficial effects: 1. It is installed under the pump and consists of an oil-gas gravity separation chamber, a primary exhaust valve, a double helix separation chamber, a secondary exhaust valve, a cyclone separation unit, etc.; when the oil-gas mixture passes through the gravity separation chamber, the flow direction is changed twice to separate large gases (bubbles); when passing through the double helix separation chamber, the flow rate of the mixture is accelerated and the centrifugal force is used to separate medium and small gases (bubbles); when passing through the cyclone separation unit, the mixture further separates the gas from the oil by impacting the tube wall and swirl, so that one tool can realize multiple ways to perform multi-stage separation of the oil-gas mixture;

[0023] 2. It is suitable for multi-stage gas-liquid separators in underground wells with high gas-liquid ratio. It can perform multi-stage separation of oil-gas mixtures through gravity, centrifugal force, cyclone impact and other methods. Under high gas-liquid ratio conditions, it can effectively improve gas separation efficiency, eliminate or reduce pump inlet gas, improve oil well pump efficiency, avoid "gas lock" of oil pumps, extend pump inspection cycle, and increase oil well production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. The drawings are only provided for reference and explanation, not for limiting the present utility model. Among them:

[0025] Figure 1 This is a schematic diagram of the structure of the utility model for the gas-proof pipe string for carbon dioxide gas cross-flow and high gas-liquid ratio oil wells;

[0026] Figure 2 for Figure 1 Enlarged view of the lower half;

[0027] Figure 3 for Figure 1 Enlarged view of the upper part;

[0028] In the figure: 1. inner tube; 2. gravity separation cylinder; 3. gravity cup; 4. gravity separation liquid inlet hole; 5. middle coupling; 6. primary exhaust valve body; 6a. primary exhaust channel; 7. primary valve ball; 8. plugging cap; 9. reducing coupling; 10. screw plug; 11. double-headed screw; 12. outer tube; 13. screw air inlet hole; 14. secondary exhaust valve body; 15. secondary valve ball; 16. valve cap; 17. special-shaped coupling; 17a. coupling axial liquid outlet hole; 17b. coupling radial exhaust hole; 18. orifice plate; 19. swirl nozzle; 20. swirl separation cylinder; 21. gas collecting hood; 22. valve ball; 23. separation body; 23a. swirl exhaust channel; 23b. separation body liquid outlet channel; 24. tail oil pipe; 25. screw plug; 26. casing. DETAILED DESCRIPTION

[0029] In the following description of the utility model, the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the utility model and simplifying the description, and do not mean that the device must have a specific direction.

[0030] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] like Figure 1 As shown, the utility model is suitable for the anti-gas pipe column of the carbon dioxide gas crosstalk and high gas-liquid ratio oil well, which includes an oil-gas gravity separation chamber, a first-stage exhaust valve, a double-helix separation chamber, a second-stage exhaust valve and a two-stage cyclone separation unit. The anti-gas pipe column is located in the casing 26, and performs multi-stage separation of the oil-gas mixture through gravity, centrifugal force, cyclone impact and other methods. In the case of high gas-liquid ratio, the gas separation efficiency is effectively improved and the pump efficiency is improved.

[0033] The oil-gas gravity separation chamber includes an inner tube 1, a gravity separation cylinder 2, a gravity cup 3, a gravity separation liquid inlet 4, and a middle hoop 5. The inner tube 1 is located in the inner cavity of the gravity separation cylinder 2 and the two are coaxial. A plurality of gravity cups 3 are mounted on the outer wall above the middle of the gravity separation cylinder 2. A plurality of gravity separation liquid inlets 4 are evenly distributed on the circumference of the gravity separation cylinder 2 near the bottom wall of the gravity cup 3. The upper end of the gravity separation cylinder 2 is screwed to the lower end of the middle hoop 5. The exhaust channel of the oil-gas gravity separation chamber is formed between the outer wall of the inner tube 1 and the inner wall of the gravity separation cylinder 2. A section of tail oil pipe 24 is screwed to the lower end of the gravity separation cylinder 2, and a threaded plug 25 is screwed to the lower end of the tail oil pipe 24.

[0034] The primary exhaust valve comprises a primary exhaust valve body 6, a primary valve ball 7 and a plugging cap 8. The outer circumference of the lower end of the primary exhaust valve body 6 is screwed to the upper end of the middle coupling 5. The upper end of the inner tube 1 is screwed to the lower end of the center hole of the primary exhaust valve body 6 and is interpenetrating. A plurality of axially interpenetrating primary axial valve holes are evenly distributed on the outer circumference of the center hole of the primary exhaust valve body 6. A primary valve ball 7 is respectively placed in the bell mouth at the lower end of each primary axial valve hole. A plugging cap 8 is respectively screwed to the upper port of the primary axial valve hole. The side wall of each primary axial valve hole is respectively provided with a primary exhaust passage 6a interpenetrating radially outward.

[0035] The double-helix separation chamber includes a reducer coupling 9, a screw plug 10, a double-headed screw 11, an outer tube 12, and a screw air inlet 13. The outer circumference of the upper end of the primary exhaust valve body 6 is screwed into the lower end female thread of the reducer coupling 9, and the outer circumference of the lower end of the outer tube 12 is screwed into the upper end female thread of the reducer coupling 9. The outer circumference of the double-headed screw 11 is wound with double-headed spiral blades, and the closer to the upper end, the smaller the pitch of the double-headed spiral blades. The double-headed screw 11 is rotatably located in the inner cavity of the outer tube 12, and the outer edge of the spiral blade is in clearance with the inner wall of the outer tube 12. The lower end of the central channel of the double-headed screw 11 is screwed with a screw plug 10, and a plurality of screw air inlets 13 are provided along the full height direction of the double-headed screw 11, and each screw air inlet 13 is evenly distributed along the spiral line.

[0036] The outer circumference of the upper end of the outer tube 12 is screwed into the inner screw hole at the lower end of the special-shaped coupling 17. The middle part of the special-shaped coupling 17 is a closed structure, and a concave special-shaped coupling exhaust chamber is provided below the central area of ​​the middle partition. The middle partition is also provided with a plurality of axially penetrating coupling axial liquid outlet holes 17a, and each coupling axial liquid outlet hole 17a is evenly distributed on the outer circumference of the special-shaped coupling exhaust chamber. The side wall of the special-shaped coupling exhaust chamber is symmetrically provided with coupling radial exhaust holes 17b that communicate with the annulus outside the special-shaped coupling 17. The coupling radial exhaust holes 17b and the coupling axial liquid outlet holes 17a are staggered in space and are not connected to each other.

[0037] The secondary exhaust valve includes a secondary exhaust valve body 14, a secondary valve ball 15 and a valve cap 16. The lower end of the secondary exhaust valve body 14 is screwed to the upper end of the double-headed screw 11. The upper part of the secondary exhaust valve body 14 is conical and embedded in the exhaust chamber of the special-shaped coupling. The outer cone surface of the conical head is pressed on the inner cone surface of the lower port of the exhaust chamber of the special-shaped coupling to close the exhaust chamber of the special-shaped coupling.

[0038] A throat is provided in the middle of the central hole of the secondary exhaust valve body 14, and a bell mouth is provided at the upper end of the throat. The secondary valve ball 15 is located in the bell mouth. A valve cap 16 is screwed on the upper end of the central hole of the secondary exhaust valve body 14, and the valve cap 16 is located in the exhaust chamber of the special-shaped coupling; a valve cap exhaust hole is provided at the top center of the valve cap 16 and communicates with the exhaust chamber of the special-shaped coupling.

[0039] The cyclone separation unit includes a special-shaped coupling 17, a cyclone nozzle 19, a cyclone separation cylinder 20, a gas collecting cover 21 and a valve ball 22. The male thread at the lower end of the cyclone separation cylinder 20 is screwed into the female thread at the upper end of the special-shaped coupling 17. The middle partition of the special-shaped coupling is covered with a perforated plate 18, the outer edge of which is pressed by the lower port of the cyclone separation cylinder. A plurality of cyclone holes are evenly distributed on the circumference of the perforated plate 18, and the lower port of each cyclone hole is respectively connected with the axial liquid outlet hole of each coupling.

[0040] The cyclone nozzle 19 is located in the lower inner cavity of the cyclone separation cylinder 20. The upper end of the cyclone separation cylinder 20 is equipped with a separation body 23. The lower end center of the separation body 23 is connected to an air collecting hood 21. The lower end of the air collecting hood 21 extends downward along the axis of the cyclone separation cylinder 20. The upper part of the central counterbore at the lower end of the separation body 23 is connected to the annular space around the tool through a cyclone exhaust channel 23a. The middle part of the central counterbore at the lower end of the separation body 23 is provided with a throat for controlling the cyclone exhaust channel 23a, and a valve ball 22 is provided at the throat. The separation body 23 is also provided with a separation body liquid outlet channel 23b that runs through the axial direction for liquid to flow out and upward.

[0041] Working principle: The oil-gas mixture in the annulus first passes through the gravity cup 3. Due to the change in flow direction, disturbance is induced, small bubbles are merged, and enter the gravity separation liquid inlet hole 4 from the bottom of the gravity cup 3. When passing through the gravity separation liquid inlet hole 4, the flow direction changes again, inducing secondary disturbance, causing the bubbles to merge into larger bubbles. Affected by the slip effect, the gas and liquid are separated by gravity difference between the gravity separation cylinder 2 and the inner tube 1. The liquid passes downward over the lower port of the inner tube 1 and enters the inner cavity of the inner tube 1. The bubbles float up through the exhaust channel of the oil-gas gravity separation chamber to achieve the second separation of gas and liquid.

[0042] When the gas pressure exceeds the pressure of the annulus on the primary valve ball 7, the primary valve ball 7 is pushed open and the gas is discharged to the annulus through the primary exhaust channel 6a. When the gas pressure drops, the primary valve ball 7 reseals the primary exhaust channel 6a under the annulus pressure to prevent the annular air and liquid from entering the gravity separation chamber.

[0043] The gas-liquid mixture that enters the inner tube 1 goes up to the double-helix separation chamber, and rotates upward along the double-helix channel. Under the action of centrifugal force, the liquid rotates outward and the gas rotates inward, and the gas and liquid are separated for the third time. The double-helix spacing of the utility model gradually decreases from bottom to top, so that the upward rotation speed of the oil-gas mixture increases, and the gas-liquid separation efficiency is further improved. The separated gas enters the inner cavity of the screw 11 through the screw air inlet hole 13 and gathers. When the gas pressure exceeds the pressure of the annulus on the secondary valve ball 15, the secondary valve ball 15 is pushed open, and the gas enters the inner cavity of the valve cap 16, and is discharged to the annulus through the valve cap exhaust hole.

[0044] When the gas pressure drops, the secondary valve ball 15 reseals the exhaust passage at the lower port of the secondary exhaust valve body 14 under the annular space pressure to prevent the annular air and liquid from entering the double helix separation chamber; the gas-liquid mixture flows upward from the axial liquid outlet 17a of the coupling.

[0045] The gas-liquid mixture flowing out of the axial liquid outlet 17a of the coupling is injected into the cyclone separation chamber along the tangent direction of the tube wall through the cyclone nozzle 19. After the mixed liquid impacts the tube wall, a cyclone is formed, and the gas and liquid are separated for the fourth time. The liquid rotates upward along the inner wall of the cyclone separation cylinder 20 under the action of centrifugal force, and then enters the annular discharge channel between the cyclone separation cylinder 20 and the gas collecting cover 21 and continues to rotate upward;

[0046] The separated gas rotates upward along the center of the separation chamber of the cyclone separation cylinder 20 and gathers in the gas collecting hood 21 in the center of the separation chamber. When the buoyancy of the gathered bubbles is greater than the weight of the valve ball 22, the valve ball 22 is pushed open and discharged into the annulus.

[0047] Similarly, the liquid goes upward and enters the cyclone separation unit above for the fifth gas-liquid separation.

[0048] In this way, the oil and gas mixture is separated five times by gravity, centrifugal force and cyclone impact, and most of the gas is separated out efficiently, effectively solving problems such as pump jam and gas lock caused by gas outlet under high gas-liquid ratio of oil wells, thereby greatly improving pump efficiency.

[0049] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The above description is only the preferred feasible embodiment of the utility model, which shows and describes the basic principle, main features and advantages of the utility model, but does not limit the scope of patent protection of the utility model. The technicians in this industry should understand that the utility model is not limited by the above embodiments. In addition to the above embodiments, the utility model can also have other implementation modes without departing from the spirit and scope of the utility model. The utility model will also have various changes and improvements. All technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the utility model. The scope of protection required by the utility model is defined by the attached claims and their equivalents. The technical features not described in the utility model can be achieved by or using existing technologies, which will not be repeated here.

Claims

1. A gas prevention pipe string suitable for carbon dioxide gas breakthrough and high gas-liquid ratio oil wells, comprising a gravity separation cylinder, characterized in that: The inner cavity of the gravity separation cylinder is coaxially provided with an inner tube, and the outer wall above the middle of the gravity separation cylinder is provided with a plurality of gravity cups, and a plurality of gravity separation liquid inlet holes are evenly distributed on the circumference of the gravity separation cylinder near the bottom wall of each gravity cup, and the upper end of the gravity separation cylinder is screwed with a primary exhaust valve body through a middle hoop, and the upper end of the inner tube is screwed with and connected to the lower end of the center hole of the primary exhaust valve body; Axially penetrating first-stage axial valve holes are symmetrically arranged on the outer circumference of the central hole of the first-stage exhaust valve body, a first-stage valve ball is respectively placed in the bell mouth at the lower end of each first-stage axial valve hole, a plugging cap is respectively screwed into the upper port of the first-stage axial valve hole, and the side wall of each first-stage axial valve hole is respectively provided with a first-stage exhaust channel penetrating radially outward.

2. The anti-gas pipe string for carbon dioxide gas breakthrough and high gas-liquid ratio oil wells according to claim 1 is characterized in that: The upper end of the primary exhaust valve body is connected to an outer tube via a reducing coupling, a double-headed screw is provided in the inner cavity of the outer tube, and a plurality of screw air inlet holes are evenly distributed along a spiral line on the circumference of the double-headed screw.

3. The anti-gas pipe string for carbon dioxide gas breakthrough and high gas-liquid ratio oil wells according to claim 2 is characterized in that: The upper end of the outer tube is screwed with a special-shaped coupling, and the upper end of the double-headed screw is screwed with a secondary exhaust valve.

4. The anti-gas pipe string for carbon dioxide gas channeling and high gas-liquid ratio oil wells according to claim 3 is characterized in that: A middle partition is provided in the middle of the special-shaped coupling, a recessed special-shaped coupling exhaust chamber is provided below the central area of ​​the middle partition, a coupling radial exhaust hole is provided on the side wall of the special-shaped coupling exhaust chamber, and a plurality of axially penetrating coupling axial liquid outlet holes are also provided on the circumference of the middle partition, and the coupling axial liquid outlet holes are evenly distributed on the outer periphery of the special-shaped coupling exhaust chamber.

5. The anti-gas pipe string for carbon dioxide gas channeling and high gas-liquid ratio oil wells according to claim 4 is characterized in that: The secondary exhaust valve includes a secondary exhaust valve body, the lower end of which is screwed to the upper end of the double-headed screw, the upper part of which is conical and embedded in the exhaust chamber of the special-shaped coupling, the outer conical surface of the conical head is pressed on the inner conical surface of the lower port of the exhaust chamber of the special-shaped coupling to close the exhaust chamber of the special-shaped coupling; a throat is provided in the middle of the central channel of the secondary exhaust valve body, a bell mouth is provided at the upper end of the throat, and a secondary valve ball is placed in the bell mouth.

6. The anti-gas pipe string for carbon dioxide gas breakthrough and high gas-liquid ratio oil wells according to claim 5, characterized in that: A valve cap is screwed onto the upper end of the central channel of the secondary exhaust valve body. The valve cap is located in the exhaust chamber of the special-shaped coupling. A valve cap exhaust hole is provided at the top center of the valve cap and communicates with the exhaust chamber of the special-shaped coupling.

7. The anti-gas pipe string for carbon dioxide gas channeling and high gas-liquid ratio oil wells according to claim 4 is characterized in that: The upper end of the special-shaped coupling is screwed with a cyclone separation unit, which includes a cyclone separation cylinder. The lower end of the cyclone separation cylinder is screwed with the upper female thread of the special-shaped coupling, and the lower end inner cavity of the cyclone separation cylinder is provided with a cyclone nozzle for guiding liquid to the inner wall of the cyclone separation cylinder.

8. The anti-gas pipe string for carbon dioxide gas channeling and high gas-liquid ratio oil wells according to claim 7 is characterized in that: The middle partition of the special-shaped coupling is covered with a orifice plate, the outer edge of the orifice plate is pressed by the lower port of the cyclone separation cylinder, and a plurality of cyclone holes are evenly distributed on the circumference of the orifice plate. The lower port of each cyclone hole is respectively connected with the axial liquid outlet hole of each coupling, and the rotation direction of each cyclone hole is the same as that of the cyclone nozzle.

9. The anti-gas pipe string for carbon dioxide gas breakthrough and high gas-liquid ratio oil wells according to claim 7, characterized in that: A separation body is installed at the upper end of the cyclone separation cylinder, and an air collecting hood is connected to the center of the lower end of the separation body. The lower end of the air collecting hood extends downward along the axis of the cyclone separation cylinder.

10. The anti-gas pipe string for carbon dioxide gas breakthrough and high gas-liquid ratio oil wells according to claim 9, characterized in that: The upper part of the central counterbore at the lower end of the separation body is connected to the annular space around the tool through a swirl exhaust channel. A throat for controlling the swirl exhaust channel is provided in the middle of the central counterbore at the lower end of the separation body, and a valve ball is provided at the throat.

11. The anti-gas pipe string for carbon dioxide gas breakthrough and high gas-liquid ratio oil wells according to claim 10, characterized in that: The separation body is also provided with a separation body liquid outlet passage which penetrates along the axial direction.

12. The anti-gas pipe string for carbon dioxide gas breakthrough and high gas-liquid ratio oil wells according to claim 7, characterized in that: The cyclone separation unit is provided with two stages in series along the axial direction.

13. The anti-gas pipe string for carbon dioxide gas breakthrough high gas-liquid ratio oil well according to any one of claims 1 to 12, characterized in that: The lower end of the gravity separation cylinder is screwed with a tail oil pipe, and the lower end of the tail oil pipe is screwed with a threaded plug.

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