A gas prevention device before a downhole oil pump

Abstract

The present disclosure relates to a pre-pump gas prevention device for a downhole oil well pump. The device comprises a first action unit, a second action unit and a guide head; the first action unit is used for a pre-separation process, which is used to reduce the axial flow velocity of the gas-liquid mixture, can remove a part of the gas, and has a certain sand prevention effect; the second action unit is used for a main separation process, which uses centrifugal force to efficiently separate the gas-liquid mixture; the device adopts a multi-stage separation structure, which can adapt to different processing volume requirements by increasing the number of sedimentation chamber sections and the length of the second action unit, and is suitable for the variable flow rate suction movement of the oil well pump. The device is arranged at the front end of the oil well pump, which can effectively reduce the gas content in the produced fluid, reduce the occurrence of gas lock and cavitation that lead to reduced pump efficiency of the oil well pump, and can improve the production efficiency of high gas-containing wells using CO2 oil recovery technology.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas field development, and in particular to a downhole oil pump supporting device applicable to the field of high-gas-containing oil well exploitation. Background Art

[0002] Most of my country's oil fields are in the middle and late stages of the exploitation stage. They cannot be driven by the internal pressure of the wellbore and need to be exploited by artificial lifting. Common lifting methods include sucker rod pumps, screw pumps, and electric submersible pump lifting. However, with the change of pressure in the wellbore, the solubility of natural gas will decrease, and some natural gas will precipitate from the oil-water mixture. On the other hand, with the development of gas flooding methods in recent years, such as the use of CO2 for oil recovery and the increase in crude oil output, these will lead to a significant increase in the gas content in the wellbore, resulting in serious pump erosion and even gas lock, which reduces the pump's lifting efficiency. At the same time, the gas content in the produced liquid will also affect the later oil-water separation and increase the processing cost.

[0003] In the prior art, there are some pre-pump anti-gas devices designed for downhole oil pumps. The basic principle is to separate the gas-liquid mixture through downhole gas-liquid separation technology, thereby realizing the pre-pump anti-gas function. For example, there is an anti-gas lock oil pump disclosed in Chinese document CN220849971U, and an anti-gas lock device disclosed in CN218717434U.

[0004] However, after research, it was found that:

[0005] The anti-gas lock oil pump disclosed in CN220849971U is a simple combination of an anti-gas device and an oil pump, without considering the influence of sand content. At the same time, the oil pump needs to be replaced when using the device, which is costly. For gas-liquid mixtures with high gas content, it cannot play a good anti-gas effect. In addition, the anti-gas pump still has cavitation.

[0006] The anti-gas lock device disclosed in CN218717434U has movable parts such as friction rings that are easily damaged, which greatly increases the maintenance cost. At the same time, it is not suitable for underground working conditions with relatively large flow rates.

[0007] In addition, there is a multi-stage sand and gas prevention device disclosed in Chinese document No. CN208669292U, which uses spiral blades to improve the anti-gas effect, but the spiral blades are difficult to manufacture and have high processing costs, and the separation efficiency is poor in the low flow rate area. The cyclone sand and gas prevention valve disclosed in Chinese document No. CN208221069U makes the fluid flow through the rotation of the propeller, thereby achieving the effect of preventing air and sand, but the rotation of the propeller will cause serious wear of the valve, increasing the maintenance cost.

[0008] Therefore, there is no effective anti-gas device before the pump at present. Summary of the invention

[0009] In order to solve the technical problems existing in the background technology, the present disclosure proposes a downhole oil pump front-pump gas prevention device, which adopts a multi-stage separation form, can be suitable for the variable flow rate suction movement of the oil pump, can effectively reduce the gas content in the produced fluid, and has a simple structure and high separation efficiency. By increasing the number of sedimentation chamber sections and the length of the second action unit, it can adapt to the requirements of different processing volumes.

[0010] According to a first aspect of the present disclosure, a device assembly is provided. The assembly includes a second acting unit.

[0011] The second action unit includes a top joint 201, a cyclone housing 202, a one-way valve 203, an overflow top cover 204, a cyclone sleeve 205 and a cyclone center tube 206;

[0012] The upper end of the swirl housing 202 is connected to the top joint 201 by threads, which plays a role of connection and fixing; the upper end of the swirl housing 202 is provided with a plurality of circular air outlets 2021;

[0013] The one-way valve 203 includes a limit plate 2031, a valve ball 2032 and a seat ring 2033;

[0014] The lower end of the limiting plate 2031 is a circular baffle, the diameter of which is the same as the inner diameter of the swirl housing 202 and is coaxial with the swirl housing 202;

[0015] The upper end of the seat ring 2033 is a circular baffle, the diameter of which is the same as the inner diameter of the swirl housing 202 and is coaxial with the swirl housing 202;

[0016] There is an annular support block at the bottom of the seat ring 2033 to allow the gas to flow out from the flow channel where the valve ball 2032 is located;

[0017] The limiting plate 2031 and the seat ring 2033 are combined to form a flow channel with a circular cross section, wherein the limiting plate 2031 and the bottom surface of the seat ring 2033 are aligned and fitted to prevent gas from entering; after alignment and fitting, the valve ball 2032 can move up and down in the limiting plate 2031 and the seat ring 2033;

[0018] The center hole of the one-way valve 203 passes through the cyclone center tube 206 and fits tightly to ensure sealing;

[0019] The limit plate 2031 is in close contact with the top joint 201, and the bottom support block of the seat ring 2033 is in close contact with the top of the overflow top cover 204, which has a fixed support function;

[0020] A tangential rectangular gas outlet groove 2041 is formed at the upper end of the overflow top cover 204 to discharge the separated gas.

[0021] A symmetrical rectangular tangential inlet 2051 is formed at the upper end of the swirl sleeve 205, and the direction of the tangential inlet is the same as that of the air outlet slot 2041;

[0022] A first circular baffle is disposed at the lower end of the overflow top cover 204. The diameter of the first circular baffle is the same as the inner diameter of the cyclone housing 202. The overflow top cover 204 is coaxially positioned with the cyclone housing 202 through the first circular baffle.

[0023] A second circular baffle is disposed at the upper end of the swirl sleeve 205. The diameter of the second circular baffle is the same as the inner diameter of the swirl housing 202. The swirl sleeve 205 is coaxially positioned with the swirl housing 202 through the second circular baffle.

[0024] The cyclone central tube 206 has a flow channel in the middle and a sedimentation chamber at the bottom. It also has four symmetrical small holes for connecting the inner and outer flow channels, so that the liquid separated by the cyclone can enter the inner flow channel through the small holes and be pumped to the ground.

[0025] The cyclone center tube 206 passes through the overflow top cover 204 and the cyclone sleeve 205 in sequence to form a seal; the upper section of the cyclone center tube 206 is connected to the top joint 201 through threads to form a seal to prevent liquid from overflowing.

[0026] Furthermore, the first circular baffle is fitted and tightly connected with the second circular baffle to prevent the liquid in the cyclone housing from flowing upward and stabilize the flow field of the second action unit.

[0027] Furthermore, the conical section of the cyclone central tube 206 is connected to the straight tube section by welding, and the range of the conical section angle α is 80°-88°.

[0028] The second aspect of the present disclosure provides a downhole oil pump front-pump air prevention device, which uses any one of the aforementioned device components, as well as a first action unit and a guide head 3.

[0029] The first action unit includes a settling shell 101, a bottom joint 102, a sand control central pipe 103 and a settling chamber 104;

[0030] The lower end of the sedimentation shell 101 is connected to the upper end of the bottom joint 102 by threads, which plays a role of fixing and supporting and preventing the gas-liquid mixture from entering;

[0031] The upper end of the settling shell 101 is provided with a plurality of inlets 1011, which are used to reduce pressure loss and allow the gas separated initially to escape to the oil casing annulus through the long strip inlets, thereby achieving the initial separation of gas and liquid;

[0032] The sand control central tube 103 is provided with two rows of small holes, one in the upper row and the other in the lower row. The small holes are used to allow the liquid in the sedimentation chamber 104 to enter the sand control central tube 103.

[0033] The settling chamber 104 is connected to the fixing pin on the outer wall of the sand control central pipe 103 through the positioning groove; the number of the settling chambers 104 is at least 2;

[0034] The guide head includes a top thread 301, a positioning block 302, a guide channel 303, an internal thread 304 and a bottom thread 305;

[0035] The guide channel 303 is located inside the guide head, with a circular inlet at the bottom and a circular outlet at the side. The fluid enters from the circular inlet at the bottom and flows out from the circular outlet at the side.

[0036] The first action unit is connected to the second action unit through the guide head 3; wherein,

[0037] The upper end of the guide head 3 is connected to the lower end of the swirl housing 202 through the top thread 301, which plays a role of connection and fixing, and at the same time forms a seal to prevent external gas from entering;

[0038] The lower end of the guide head 3 is connected to the upper end of the sedimentation shell 101 through a bottom thread 305; the guide flow channel 303 is connected to the upper end of the sand control central tube 103 through an internal thread 304, and the guide flow channel 303 is used to change the flow direction of the mixture so that the gas-liquid mixture in the sand control central tube 103 can flow through the guide flow channel 303 and enter the second action unit;

[0039] The positioning block 302 is tightly connected to the annular gap at the lower end of the swirl sleeve 205 and the lower end of the swirl center tube 206 to form a seal to prevent the liquid from flowing out;

[0040] The positioning block 302 is clamped with the cyclone center tube 206 to form a seal to prevent liquid from spilling;

[0041] The outlet area of ​​the circular gas outlet 2021 is smaller than the inlet area of ​​the inlet 1011, so as to facilitate the discharge of the separated gas;

[0042] The gas-liquid mixture preliminarily separated by the first action unit enters through the tangential inlet.

[0043] Furthermore, the bottom of the sedimentation chamber is in an arc shape, which can form a liquid surface at the bottom of the chamber during the sedimentation process to prevent subsequent gas from entering.

[0044] Furthermore, the inlet 1011 is a long strip-shaped inlet with rounded corners, which is used to reduce pressure loss and allow the initially separated gas to escape to the oil casing annulus through the inlet, thereby achieving the first separation of gas and liquid.

[0045] Furthermore, at least four axially symmetrical circular outlets are opened on the side of the guide flow channel 303, and the fluid enters from the bottom circular inlet and flows out from the side circular outlet, which has the effect of stabilizing the flow field.

[0046] At least one of the above technical solutions adopted in one or more embodiments of this specification can achieve the following beneficial effects:

[0047] First of all, the pre-pump anti-gas device proposed in the present invention adopts multi-stage separation, and combines the functions of the first acting unit and the second acting unit, thereby overcoming the problem of poor anti-gas effect of the existing pre-pump anti-gas device under variable flow rate conditions. It can fully adapt to the full speed range of the downhole oil pump and provide a stable anti-gas effect.

[0048] Secondly, compared with the anti-gas lock oil well pump, the installation and replacement is simpler and can be directly installed under the oil well pump through the joint, saving the cost of replacing the oil well pump.

[0049] Again, the pre-pump air proof device proposed in the present invention is simpler and more compact in structure than other pre-pump air proof devices. On the one hand, it is easy to process, reduces processing costs, and ensures the safety of production operations. On the other hand, the main separation structure inside the device has no moving parts, has high working stability, and can reduce maintenance costs.

[0050] In addition, the pre-pump anti-gas device proposed in the present invention relies on the synergistic effect of gravity and centrifugal force to have a certain sand prevention function, and at the same time realizes efficient air prevention outside the pump. It is superior to traditional anti-gas devices outside the pump and can be suitable for high-gas oil wells. At the same time, the required space is smaller, which helps to promote the development of the pre-pump anti-gas device of the downhole oil pump towards a miniaturized design.

[0051] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0052] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and are used to illustrate the technical solutions of the present disclosure together with the specification.

[0054] FIG. 1( a ) is a partial cross-sectional view of the front-pump air-proof device of the present disclosure.

[0055] FIG1( b ) is an overall structural diagram of the pre-pump air prevention device disclosed in the present invention.

[0056] Figure 2 It is a partial cross-sectional view of the second acting unit of the present disclosure.

[0057] Figure 3 It is a partial cross-sectional view of the first acting unit of the present disclosure.

[0058] Figure 4 This is a disassembled diagram of the cyclone center tube connection method disclosed in the present invention.

[0059] Figure 5 This is a disassembled diagram of the connection method of the second action unit disclosed in the present invention.

[0060] Figure 6 This is a disassembled diagram of the guide head connection method disclosed in the present invention.

[0061] Figure 7 This is a disassembled diagram of the one-way valve described in the present invention.

[0062] Figure 8 This is a parts drawing of the guide head disclosed in the present invention.

[0063] Fig. 9 This is a disassembled diagram of the sand control central pipe connection method disclosed in the present invention.

[0064] FIG. 10( a ) is a disassembled diagram of the overflow top cover swirl sleeve connection method disclosed in the present invention.

[0065] FIG10( b ) is a partial cross-sectional view of the overflow top cover and the swirl sleeve described in the present invention.

[0066] Fig.11 It is a cross-sectional view of the cyclone center tube described in the present invention.

[0067] Fig.12 It is a schematic diagram of the principle of the pump front air protection device disclosed in the present invention.

[0068] Fig.13 The figure is an overall cross-sectional view of the pump front air protection device disclosed in the present invention.

[0069] In the figure: 101-sedimentation shell; 1011-inlet; 102-bottom joint; 103-sand control center tube; 104-sedimentation chamber; 201-top joint; 202-cyclone shell; 2021-air outlet; 203-check valve; 2031-limiting plate; 2032-valve ball; 2033-seat ring; 204-overflow top cover; 2041-rectangular air outlet groove; 205-cyclone sleeve; 2051-tangential inlet; 206-cyclone center tube; 3-guide head; 301-top thread; 302-positioning block; 303-guide flow channel; 304-internal thread; 305-bottom thread. DETAILED DESCRIPTION

[0070] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0071] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods and means well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present disclosure.

[0072] A specific embodiment of the anti-gas device disclosed in the present invention is given below:

[0073] As shown in FIG. 1 , the downhole oil pump front-pump anti-gas device disclosed in the present disclosure comprises a first action unit, which comprises a settling shell 101 , a bottom joint 102 , a sand-proof central pipe 103 and a settling chamber 104 .

[0074] The lower end of the sedimentation shell 101 is connected to the upper end of the bottom joint 102 through threads, which plays a role of fixing and supporting, and prevents the gas-liquid mixture from entering.

[0075] like Figure 3 As shown, the upper end of the sedimentation shell 101 is provided with 4-8 long strip inlets 1011 with rounded corners, the size of which is determined by the actual working conditions, for reducing pressure loss. Meanwhile, the gas separated in the initial separation stage can escape to the oil casing annulus through 1011, thus realizing the first separation of gas and liquid.

[0076] like Fig. 9 As shown, the sand control central pipe 103 is provided with two rows of small holes, one in the upper row and the other in the lower row. Each row has four holes of specific sizes, the number of which is determined by actual working conditions, so that the liquid in the sedimentation chamber 104 can enter the sand control central pipe 103 .

[0077] The settling chamber 104 is connected to the fixing pin on the outer wall of the sand control central pipe 103 through the positioning groove, which is convenient for installation and disassembly and is also beneficial for processing and production. The number of the settling chambers 104 is 2 or more, which can be adjusted according to actual working conditions such as the processing volume.

[0078] The bottom of the sedimentation chamber 104 is in an arc shape, which is conducive to forming a liquid surface at the bottom of the chamber during the sedimentation process, preventing subsequent gas from entering and enhancing the separation effect.

[0079] like Figure 2 As shown, the downhole oil pump front air prevention device also includes a second action unit, which includes a top joint 201, a swirl shell 202, a one-way valve 203, an overflow top cover 204, a swirl sleeve 205, and a swirl center tube 206.

[0080] The upper end of the cyclone housing 202 is connected to the top joint 201 by threads, which plays a role of connection and fixing. The upper end of the cyclone housing 202 is provided with 4-8 circular gas outlets 2021, the size of which is determined by the actual working conditions, and the area is smaller than the inlet 1011, so that the separated gas can be discharged.

[0081] like Figure 7 As shown, the one-way valve 203 is composed of a limit plate 2031, a valve ball 2032, and a seat ring 2033. There is a flow channel with a circular cross section between the limit plate 2031 and the seat ring 2033. The limit plate 2031 and the seat ring 2033 are aligned and fit, and have a certain sealing property to prevent gas from entering. At the same time, the flow channel cross section is aligned, so that the valve ball 2032 can move up and down in the limit plate 2031 and the seat ring 2033, so that it can play a normal function.

[0082] like Figure 5 As shown, the lower end of the limiting plate 2031 is a circular baffle, the diameter of which is the same as the inner diameter of the cyclone housing 202, and while ensuring coaxiality with the cyclone housing 202, it has a certain sealing performance.

[0083] The upper end of the seat ring 2033 is a circular baffle, the diameter of which is the same as the inner diameter of the cyclone housing 202, and has a certain sealing performance while ensuring coaxiality with the cyclone housing 202. The bottom of the seat ring 2033 has an annular support block to allow gas to flow out from the flow channel where the valve ball 2032 is located.

[0084] The center hole of the one-way valve 203 fits tightly through the cyclone center tube 206 to ensure sealing. The limit plate 2031 is in close contact with the top joint 201. The bottom support block of the seat ring 2033 fits tightly with the top of the overflow top cover 204 to provide fixed support.

[0085] As shown in FIG. 10 , a tangential rectangular gas outlet slot 2041 is opened at the upper end of the overflow top cover 204 , and the size and number of the slots are determined by the actual processing volume, so that the separated gas can be discharged.

[0086] The upper end of the swirl sleeve 205 is provided with symmetrical tangential inlets 2051 in rectangular shape, 2 in number, and in the same direction as the gas outlet slot 2041. The gas-liquid mixture preliminarily separated by the first action unit enters through it, and the size is determined by the actual processing capacity.

[0087] The overflow top cover 204 has a circular baffle at the lower end, and the diameter is the same as the inner diameter of the cyclone housing 202. The overflow top cover 204 can maintain coaxial positioning with the cyclone housing 202 through the baffle at the lower end.

[0088] The upper end of the swirl sleeve 205 is provided with a circular baffle, the diameter of which is the same as the inner diameter of the swirl housing 202. The swirl sleeve 205 can be coaxially positioned with the swirl housing 202 through the baffle at the upper end.

[0089] The circular baffle at the lower end of the overflow top cover 204 fits tightly with the circular baffle at the upper end of the cyclone sleeve 205. The baffle can prevent the liquid in the cyclone housing from flowing upward, stabilize the flow field of the second action unit, and enhance the separation effect.

[0090] A flow channel is opened in the middle of the cyclone central tube 206, and a small sedimentation chamber is opened at the bottom. At the same time, four symmetrical small holes are opened to connect the inner and outer flow channels, so that the liquid after the second action unit can enter the internal flow channel from the small holes and be pumped to the ground.

[0091] The upper section of the cyclone central tube 206 is connected to the top joint 201 by threads to form a seal to prevent liquid from spilling. The conical section of the cyclone central tube 206 is connected to the straight tube section by welding. Fig.11 As shown, the cone angle α of the cone section ranges from 80° to 88°, and other dimensions are determined by the actual processing volume. Figure 4 As shown, the cyclone central tube 206 passes through the overflow top cover 204 and the cyclone sleeve 205 in sequence to form a seal to prevent liquid from overflowing.

[0092] like Figure 8 As shown, the downhole oil pump front air prevention device further includes a guide head 3 , which includes a top thread 301 , a positioning block 302 , a guide channel 303 , an internal thread 304 , and a bottom thread 305 .

[0093] like Figure 6 As shown, the upper end of the guide head 3 is connected to the lower end of the swirl housing 202 via a top thread 301, which plays a role in connection and fixation, and at the same time forms a seal to prevent external gas from entering.

[0094] The positioning block 302 is tightly connected with the annular gap between the lower end of the swirl sleeve 205 and the lower end of the swirl center tube 206 to form a seal to prevent liquid from flowing out. The positioning block 302 is clamped with the swirl center tube 206 to form a seal to prevent liquid from overflowing.

[0095] The guide channel 303 is located inside the guide head 3, with a circular inlet at the bottom and four axially symmetrical circular outlets at the side. The fluid enters from the circular inlet at the bottom and flows out from the side outlets, which has the function of stabilizing the flow field.

[0096] The guide channel 303 is connected to the upper end of the sand control central tube 103 through an internal thread 304, and has a fixed support and sealing function. The guide channel 303 can also change the flow direction of the mixture, so that the gas-liquid mixture in the sand control central tube 103 can flow through the guide channel 303 and enter the second action unit.

[0097] The lower end of the guide head 3 is connected to the upper end of the sedimentation shell 101 through a bottom thread 305, and has a certain sealing performance.

[0098] Furthermore, after the first action unit and the second action unit are connected through the guide head 3, a downhole oil pump front gas prevention device is formed;

[0099] The first action unit is combined with the second action unit to separate the gas-liquid two phases. The first action unit is used for pre-separation, which is applicable to the low flow rate area of ​​the oil well pump and has the function of desanding. The second action unit is used as the main separation method. Since centrifugal separation shows a higher separation effect, it can perform efficient gas-liquid separation and is applicable to the high flow rate area of ​​the oil well pump. In the separation process, the guide head, inner cone section, baffle structure and tangential inlet and outlet structures are used to change the flow direction of the fluid, thereby enhancing the separation effect.

[0100] Since the suction motion of the downhole oil pump is periodically changed and there are two intervals of low flow rate and high flow rate, the first action unit has a good separation effect in the low speed interval, while the second action unit can adapt well to the high speed area. Therefore, the above structure can achieve a higher separation effect in the full flow rate range of the oil pump.

[0101] The working process and principle are introduced as follows: Fig.12 As shown, when the downhole oil pump front gas prevention device works normally, the gas-liquid mixture enters from the long strip inlet 1011 below the separator. When the gas-liquid mixture passes through the long strip inlet 1011, due to the slip effect, that is, due to the difference in the velocity of the gas-liquid two phases, part of the gas continues to rise from the oil casing annulus, and the gas-liquid mixture is initially separated. A part of the gas-liquid mixture, that is, the gas-liquid mixture after the initial separation, enters the first action unit.

[0102] In the first action unit, the separation process is as follows:

[0103] The gas-liquid mixture entering the first action unit first passes through the upper sedimentation chamber 104. Due to the large difference in density between gas and liquid, the speeds in the flow channel are different. The liquid has a faster speed and enters the sedimentation chamber 104 first, and enters the sand control central pipe 103 through a circle of small holes at the bottom of the sedimentation chamber, and continues to flow upward to enter the subsequent second action unit. On the other hand, due to the viscosity of the liquid, it is adsorbed at the bottom of the sedimentation chamber 104. At the same time, due to the limitation of the diameter of the small holes, a liquid surface will be formed at the bottom of the sedimentation chamber, which will hinder part of the gas from entering the sand control central pipe 103. The blocked gas is discharged from the long strip inlet 1011 to the oil casing annulus, reducing the gas content in the mixture and completing a separation process.

[0104] The gas-liquid mixture that has not been separated by the upper sedimentation chamber 104 enters the next sedimentation chamber 104 through the annular gap between the sedimentation chamber 104 and the sedimentation shell 101 for sedimentation separation. The above process is repeated to achieve the purpose of separation of the first action unit.

[0105] The first action unit is a secondary separation process. During this process, the axial velocity of the gas is reduced due to the obstruction of the multi-stage sedimentation chamber, and the gas stays in the sedimentation chamber for a longer time. Therefore, compared with the traditional gas prevention device, the separation effect is better. On the other hand, due to the action of the first action unit, the gas content is reduced, which is conducive to the second action unit.

[0106] After the secondary separation, the gas-liquid mixture passes through the sand-proof central pipe 103 and the guide head 3 and flows upward through the pipeline. During this process, due to the effect of gravity, substances with higher density, such as sand particles, will fall downward, thereby separating the solid particles and preventing the narrow flow channel from being blocked, which has a certain sand-proof effect.

[0107] In the second action unit, the separation process is as follows:

[0108] The gas-liquid mixture flowing upward from the pipeline can only enter the swirl sleeve 205 for separation from the tangentially symmetrical inlet 2051 due to the obstruction of the baffle at the upper end of the swirl sleeve 205. The gas-liquid mixture rotates in the swirl sleeve 205. Since the area of ​​the symmetrical inlet 2051 is smaller than the cross-section of the pipeline, the tangential velocity of the gas-liquid mixture increases, thereby having a greater centrifugal force in the swirl sleeve 205. Among them, due to the difference in gas and liquid density, the centrifugal force is different. The gas with relatively small density will gather at the center and rotate, while the liquid with larger density will rotate close to the inner wall of the swirl sleeve 205.

[0109] Due to the suction force from the oil pump in the swirl center tube 206 and the gravity of the liquid itself, the liquid at the inner wall of the swirl sleeve 205 will rotate and move downward, be sucked by the cyclone center tube 206 and discharged to the ground by the oil pump. At the same time, the liquid flows through the narrow space at the bottom of the swirl sleeve 205 to form a liquid surface, which hinders the gas from entering the swirl center tube 206. The gas rotating in the center of the swirl sleeve will be affected by the suction force of the pump, but because the gas converges in the center, the volume increases, causing the buoyancy to increase accordingly. At the same time, due to the obstruction of the inner cone section of the swirl center tube 206, an upward thrust will be applied to the gas. The buoyancy and thrust are much greater than the downward suction, and the gas will continue to rise, flow through the overflow top cover 204 and be discharged from the tangential outlet 2041. At the same time, the upward force is greater than the gravity of the valve ball 2032 in the one-way valve 203, and the gas lifts up the valve ball 2032, and finally flows from the gas outlet 2021 at the top of the cyclone housing 202 to the oil casing annulus, completing the separation process of the second action unit.

[0110] The second action unit is a three-stage separation process. Since the centrifugal force is much greater than the gravity, the separation effect is better than gravity separation, so this separation process is the main separation stage. On the other hand, due to the obstruction of the inner cone at the bottom of the cyclone and the liquid surface formed by the liquid, the gas can be effectively prevented from being sucked into the cyclone center tube, thereby improving the separation effect.

Claims

1. A device assembly for a downhole oil well pump front gas prevention device, comprising a second action unit, characterized in that: The second action unit comprises a top joint (201), a cyclone housing (202), a one-way valve (203), an overflow top cover (204), a cyclone sleeve (205) and a cyclone central tube (206); The upper end of the swirl shell (202) is connected to the top joint (201) by means of threads, which plays a role of connection and fixing; the upper end of the swirl shell (202) is provided with a plurality of circular air outlets (2021); The one-way valve (203) comprises a limit plate (2031), a valve ball (2032) and a seat ring (2033); The lower end of the limiting plate (2031) is a circular baffle, the diameter of which is the same as the inner diameter of the cyclone housing (202), and is coaxial with the cyclone housing (202); The upper end of the seat ring (2033) is a circular baffle, the diameter of which is the same as the inner diameter of the swirl shell (202) and is coaxial with the swirl shell (202); The bottom of the seat ring (2033) is provided with an annular support block to enable gas to flow out from the flow channel where the valve ball (2032) is located; The limiting plate (2031) and the seat ring (2033) are combined to form a flow channel with a circular cross section, wherein the limiting plate (2031) and the bottom surface of the seat ring (2033) are aligned and fitted to prevent gas from entering; after the alignment and fitting, the valve ball (2032) can move up and down in the limiting plate (2031) and the seat ring (2033); The center hole of the one-way valve (203) passes through the cyclone center tube (206) and fits tightly to ensure sealing; The limiting plate (2031) is in close contact with the top joint (201), and the bottom support block of the seat ring (2033) is in close contact with the top of the overflow top cover (204), which has a fixed support function; A tangential rectangular gas outlet groove (2041) is formed at the upper end of the overflow top cover (204) for discharging the separated gas. A symmetrical rectangular tangential inlet (2051) is provided at the upper end of the swirl sleeve (205), and the direction of the rectangular tangential inlet is the same as the direction of the air outlet groove (2041); A first circular baffle is provided at the lower end of the overflow top cover (204), the diameter of the first circular baffle being the same as the inner diameter of the cyclone housing (202), and the overflow top cover (204) is coaxially positioned with the cyclone housing (202) through the first circular baffle; A second circular baffle is provided at the upper end of the swirl sleeve (205), the diameter of the second circular baffle being the same as the inner diameter of the swirl housing (202), and the swirl sleeve (205) is coaxially positioned with the swirl housing (202) through the second circular baffle; The cyclone central tube (206) has a flow channel in the middle and a sedimentation chamber at the bottom. It also has four symmetrical small holes for connecting the inner and outer flow channels, so that the liquid separated by the cyclone can enter the inner flow channel through the small holes and be pumped to the ground. The cyclone central tube (206) passes through the overflow top cover (204) and the cyclone sleeve (205) in sequence to form a seal; the upper section of the cyclone central tube (206) is connected to the top joint (201) through threads to form a seal to prevent liquid from overflowing.

2. A device assembly for a downhole oil well pump front air prevention device according to claim 1, characterized in that: The first circular baffle is fitted and tightly connected to the second circular baffle, and is used to prevent the liquid in the cyclone housing from flowing upward and stabilize the flow field of the second action unit.

3. The device assembly for the downhole oil pump front air prevention device according to claim 2, characterized in that: The conical section of the cyclone central tube (206) is connected to the straight tube section by welding, and the range of the conical angle α of the conical section is 80°-88°.

4. A downhole oil pump front gas prevention device, using any one of the device components described in claims 1 to 3, characterized in that: The device also includes a first action unit and a guide head (3); The first action unit comprises a settling shell (101), a bottom joint (102), a sand control central pipe (103) and a settling chamber (104); The lower end of the sedimentation shell (101) is connected to the upper end of the bottom joint (102) by threads, which plays a role of fixing and supporting and preventing the gas-liquid mixture from entering; The upper end of the sedimentation shell (101) is provided with a plurality of inlets (1011) for reducing pressure loss and allowing the gas separated initially to escape to the oil casing annulus through the long strip-shaped inlets, thereby achieving the initial separation of gas and liquid; The sand control central tube (103) is provided with two rows of small holes, one in the upper row and the other in the lower row. The small holes are used to allow the liquid in the sedimentation chamber (104) to enter the sand control central tube (103); The settling chamber (104) is connected to a fixing pin on the outer wall of the sand control central pipe (103) through a positioning groove; the number of the settling chambers (104) is at least 2; The guide head comprises a top thread (301), a positioning block (302), a guide channel (303), an internal thread (304) and a bottom thread (305); The guide flow channel (303) is located inside the guide head, with a circular inlet at the bottom and a circular outlet at the side, and the fluid enters from the circular inlet at the bottom and flows out from the circular outlet at the side; The first action unit is connected to the second action unit via a guide head (3); wherein, The upper end of the guide head (3) is connected to the lower end of the swirl housing (202) via a top thread (301), which plays a role of connection and fixing, and at the same time forms a seal to prevent external gas from entering; The lower end of the guide head (3) is connected to the upper end of the sedimentation shell (101) via a bottom thread (305); the guide flow channel (303) is connected to the upper end of the sand control central tube (103) via an internal thread (304); the guide flow channel (303) is used to change the flow direction of the mixture so that the gas-liquid mixture in the sand control central tube (103) can flow through the guide flow channel (303) and enter the second action unit; The positioning block (302) is tightly connected to the annular gap at the lower end of the swirl sleeve (205) and the lower end of the swirl center tube (206) to form a seal to prevent liquid from flowing out; The positioning block (302) is clamped tightly with the cyclone center tube (206) to form a seal to prevent liquid from spilling; The outlet area of ​​the circular gas outlet (2021) is smaller than the inlet area of ​​the inlet (1011), so as to facilitate the discharge of the separated gas; The gas-liquid mixture preliminarily separated by the first action unit enters through the tangential inlet.

5. A downhole oil pump front-pump air prevention device according to claim 4, characterized in that: The bottom of the sedimentation chamber is in an arc shape, and a liquid surface can be formed at the bottom of the chamber during the sedimentation process to prevent subsequent gas from entering.

6. A downhole oil pump front-pump air prevention device according to claim 5, characterized in that: The inlet (1011) is a long strip-shaped inlet with rounded corners, which is used to reduce pressure loss and allow the gas separated initially to escape to the oil casing annulus through the inlet, thereby achieving the first separation of gas and liquid.

7. A downhole oil pump front-pump air prevention device according to claim 6, characterized in that: At least four axially symmetrical circular outlets are opened on the side of the guide flow channel (303), and the fluid enters from the bottom circular inlet and flows out from the side circular outlet, which has the function of stabilizing the flow field.

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