Composite gas lift device and manufacturing method thereof

Abstract

The invention discloses a composite gas lift device and a manufacturing method thereof. The composite gas lift device comprises an upper connector, an outer working barrel and a lower connector which are sequentially and fixedly connected from top to bottom. An inner sliding sleeve capable of sliding up and down is arranged in the outer working barrel, and a central flow channel, an upper annular cavity body and a lower annular cavity body are formed in the inner sliding sleeve; the side wall of the outer working barrel is provided with at least one group of air inlet channels, each air inlet channel is provided with an upper air inlet and a lower air inlet, and the upper end of the upper joint is provided with an air injection hole communicated with the air inlet channel in a penetrating manner; and an upper group of runner holes and a lower group of runner holes are formed in the side wall of the inner sliding sleeve, and are respectively upper runner holes and lower runner holes. The device has the advantages that the device can be flexibly switched between a continuous stable lifting mode and an efficient intermittent lifting mode according to the productivity change of an oil well, so that the device has the advantages of stable production of a high-yield well and efficient lifting of a low-yield well.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, specifically to a composite gas lift device and its manufacturing method. Background Technology

[0002] Gas lift is a widely used artificial lifting method in oilfield production. Currently, there are two main types of gas lift: continuous flow gas lift and intermittent gas lift.

[0003] Continuous flow gas lift involves injecting a continuous gas flow into the formation fluid to reduce the fluid density inside the tubing. The pressure difference between the formation pressure and the bottom hole flowing pressure allows the fluid to flow continuously out of the wellhead. Its advantages are stable production and convenient management. Its disadvantages are low lifting efficiency, large gas slippage loss, and poor economic benefits in oil wells with low production, low permeability, and low formation energy.

[0004] Chamber-type gas lift is a type of intermittent gas lift. Its working principle is to first gather the formation fluid in a specific chamber, and then inject high-pressure gas into the top of the chamber to quickly lift the fluid gathered in the chamber to the surface. Its advantages are that it is suitable for low-production wells and has high instantaneous fluid discharge efficiency. Its disadvantages are that production is discontinuous, wellhead production fluctuates greatly, it requires a complex time controller, and it has a significant impact on the surface gathering and transportation system.

[0005] Current gas lift tools have limited functionality and cannot simultaneously achieve stable production in high-yield wells and efficient lifting in low-yield wells, thus requiring improvement. Summary of the Invention

[0006] The purpose of this invention is to provide a composite gas lift device and its manufacturing method, which can flexibly switch between two modes, continuous and stable lift and high-efficiency intermittent lift, according to changes in oil well production capacity. This simultaneously takes into account the advantages of stable production in high-yield wells and high-efficiency lift in low-yield wells, thus solving the problems in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A composite air lift device and its manufacturing method include: The upper connector, outer working cylinder, and lower connector are fixedly connected sequentially from top to bottom; The outer working cylinder is provided with an inner sliding sleeve that can slide up and down. The inner sliding sleeve forms a central flow channel, an upper annular cavity, and a lower annular cavity. At least one set of air inlet channels are provided on the side wall of the outer working cylinder. The air inlet channels are provided with an upper air inlet hole and a lower air inlet hole. An air injection hole communicating with the air inlet channel is provided through the upper end of the upper connector. The inner sliding sleeve has two sets of flow channel holes on its side wall, namely the upper flow channel hole and the lower flow channel hole. A central disc is fixed to the outer wall of the inner sliding sleeve, and a sealing ring is fixed to the side wall of the central disc. The sealing ring is used to seal the annular space between the inner sliding sleeve and the outer working cylinder. The top of the inner sliding sleeve is provided with a limiting shoulder, and the bottom of the inner sliding sleeve is provided with an annular force-bearing shoulder for limiting. The upper stop point is the position where the inner sliding sleeve slides upward until its top limiting shoulder abuts against the lower end of the upper connector. The lower stop point is the position where the inner sliding sleeve slides downward until its bottom annular force-bearing shoulder abuts against the lower connector or is blocked by the lower connector. It also includes a switching rod for driving the inner sliding sleeve to slide up and down. The switching rod is a long strip of metal rod with an arc-shaped guide head at the top and a flat impact head at the bottom. The limiting shoulder at the top of the inner sliding sleeve is adapted to the flat impact head. An air outlet pipe is provided at the lower part of the inner sleeve; The device has two operating states: The first working state is the chamber-type gas lift mode: when the inner sleeve is at the bottom dead center, the lower flow channel hole is blocked by the inner wall of the outer working cylinder. At this time, the upper flow channel hole is connected to the upper air inlet hole on the outer working cylinder. High-pressure gas enters the upper part of the central flow channel through the air inlet channel, the upper air inlet hole and the upper flow channel hole, and then flows out from the outlet pipe through the central flow channel, which is used to lift the liquid in the outer working cylinder. The second working state is the continuous flow air lift mode: when the inner sliding sleeve is at the top dead center, the upper flow channel hole is blocked by the inner wall of the outer working cylinder, and the lower flow channel hole is connected to the lower annular cavity. At this time, high-pressure gas enters the lower annular cavity through the air inlet channel and the lower air inlet hole, and then is injected into the fluid in the central flow channel through the lower flow channel hole. Finally, it flows out from the outlet pipe through the central flow channel, which is used to lift the liquid in the outer working cylinder.

[0008] Preferably, the sidewall of the annular force-bearing shoulder fits into the inner wall of the outer working cylinder.

[0009] It is worth noting that this design can limit the radial offset during the sliding process of the inner sleeve, avoid misalignment between the sealing ring and the inner wall of the outer working cylinder due to shaking, and thus damage the sealing performance. At the same time, it can ensure that the force is evenly distributed when the annular force-bearing shoulder abuts against the lower connector, prevent local stress concentration from causing component deformation, effectively prevent high-pressure gas from leaking from the annulus, ensure the sealing performance and working stability when switching between the two gas lift modes, and extend the service life of vulnerable parts such as the sealing ring.

[0010] Preferably, both the upper and lower connectors are nut-shaped structures.

[0011] It is worth noting that the nut-shaped structure is compatible with the threaded connection standards of conventional downhole tools, eliminating the need for additional customized connection components. This simplifies the assembly process of the device and the downhole tubing, reduces the difficulty of on-site construction operations, and improves work efficiency. At the same time, the threaded connection has a higher engagement depth and strength, which can withstand the impact of complex working conditions such as downhole vibration and pressure fluctuations. This can prevent the connection between the joint and the outer working cylinder from loosening, ensuring the overall structural stability of the device and reducing the risk of downhole failure.

[0012] Preferably, at least two central flow channels are provided.

[0013] It is worth noting that the multi-center flow channel design can increase the cross-sectional area of ​​fluid flow, reduce fluid flow resistance, significantly improve the gas lift discharge rate, and adapt to the gas lift requirements of high-volume wells. At the same time, the multiple channels can form a redundant design, so even if a single channel is blocked by impurities, the other channels can still work normally, avoiding the equipment from stopping operation due to the failure of a single channel. This can greatly improve the reliability of the equipment and reduce the frequency and cost of downhole maintenance.

[0014] Preferably, the radius of curvature of the arc-shaped guide head of the switching rod is 5-10mm, the flatness of the end face of the planar impact head is not greater than 0.05mm, and the diameter of the planar impact head is not less than the inner diameter of the annular force-bearing shoulder at the top of the inner sliding sleeve.

[0015] It is worth noting that: a guide head with a curvature radius of 5-10mm can reduce the resistance when the switching rod enters the inner slide sleeve, avoiding switching failure due to jamming at sharp corners; an impact head with a flatness of ≤0.05mm can ensure a tight fit with the limiting shoulder, so that the impact force is evenly transmitted to the inner slide sleeve, which can prevent the shoulder from deforming due to local stress; and an impact head diameter that matches the inner diameter of the shoulder can avoid misalignment during impact, ensuring that the inner slide sleeve slides accurately to the target stop point, thus guaranteeing the accuracy and stability of switching between the two air lift modes.

[0016] Preferably, the center of the upper flow channel hole and the center of the lower flow channel hole are located on the same vertical line.

[0017] It is worth noting that the vertical design facilitates hole positioning during the machining of the inner sliding sleeve, reduces machining difficulty and errors, ensures the alignment accuracy of the flow channel hole and the air inlet hole on the outer working cylinder, and when the inner sliding sleeve switches between sliding modes, the flow channel hole can accurately align with the upper and lower air inlets along the vertical direction, avoiding gas flow obstruction due to hole position offset, ensuring that high-pressure gas stably enters the central flow channel, maintaining gas lift efficiency, and the symmetrical hole layout can balance the force on the inner sliding sleeve and reduce jamming during sliding.

[0018] Preferably, a fixed air lift valve is connected to the air intake channel on the outer working cylinder.

[0019] It is worth noting that: fixed gas lift valves can precisely control the intake pressure and flow rate, avoiding sudden increases or decreases in intake volume due to downhole pressure fluctuations, ensuring stable gas supply during the gas lift process, maintaining gas lift efficiency, and filtering impurities in the intake air to prevent impurities from entering the device and clogging the flow channel or wearing the sealing ring, reducing component failures. Moreover, its fixed installation method does not require frequent adjustments, which can reduce downhole maintenance needs and improve the long-term working stability of the device.

[0020] Preferably, a valve body is provided on the air outlet pipe.

[0021] It is worth noting that the valve body can flexibly control the opening and closing of the gas outlet pipe. When the device is under maintenance or the mode is switched, the valve body is closed to prevent downhole fluid from flowing back into the device, avoiding blockage of the flow channel or corrosion of components. At the same time, in the chamber gas lift mode, the discharge rate can be controlled by adjusting the valve body opening to adapt to the discharge requirements of different well conditions. In addition, the sealing structure of the valve body can enhance the sealing performance of the gas outlet pipe, preventing high-pressure gas from leaking from the discharge end and ensuring stable gas lift pressure.

[0022] Preferably, the upper inner wall of the inner sleeve is provided with an air injection pipe for air intake. The air injection pipe and the upper flow channel hole are interconnected inside the inner sleeve. When the air injection pipe is interconnected with the upper air intake hole, both the upper flow channel hole and the lower flow channel hole are blocked by the inner wall of the outer working cylinder.

[0023] It is worth noting that the gas injection connector can realize the pre-injection function, injecting low-pressure gas into the device before mode switching to balance the internal and external pressure, reduce the pressure shock during switching, and avoid damage to the sealing ring or flow channel hole by the instantaneous impact of high-pressure gas. At the same time, this structure can expand the device's adaptability range. Under low-pressure conditions, the gas injection connector can stably introduce gas, avoiding poor gas intake in the upper flow channel hole due to excessively low pressure, and improving the device's applicability to well conditions with different pressures.

[0024] The present invention also provides a method for manufacturing a composite air lift device, the method comprising the following steps: S1: Machining basic components The upper connector, lower connector, and outer working cylinder are machined separately. Internal threads are machined on the inner walls of the upper and lower connectors, and external threads are machined on the outer walls. An air injection hole communicating with the air intake channel is machined through the upper end of the upper connector. At least one set of air intake channels is machined on the side wall of the outer working cylinder. The air intake channels need to be formed with upper air intake holes and lower air intake holes, and a connection structure for connecting with a fixed air lift valve is reserved.

[0025] S2: Processing core functional components Machining of the inner sliding sleeve: The center flow channel, upper annular cavity, and lower annular cavity are machined inside the cylindrical billet; Machine the annular groove for installing the sealing ring on its outer wall, and machine the upper flow channel hole and the lower flow channel hole on the side wall to ensure that the centers of the upper flow channel hole and the lower flow channel hole are on the same vertical line. Machine a limiting shoulder and an annular force-bearing shoulder at the top to ensure that the sidewalls of the limiting shoulder and the annular force-bearing shoulder can fit against the inner wall of the outer working cylinder. The installation structure of the gas injection pipe is machined on the upper inner wall to ensure that the gas injection pipe and the upper flow channel hole are internally interconnected, and when the gas injection pipe is connected to the upper air inlet hole, both the upper and lower flow channel holes can be blocked by the inner wall of the outer working cylinder. The assembly interface for the air pipe is machined at the bottom.

[0026] Processing of the switching rod: The rod is made of metal and its length is adapted to the well depth, while its diameter is smaller than the inner diameter of the production tubing. A circular arc-shaped guide head is machined at the top of the rod, and a flat impact head is machined at the bottom. The diameter is not less than the inner diameter of the annular force-bearing shoulder at the top of the inner sleeve, and the end face roughness Ra≤1.6μm.

[0027] S3: Enhancement Processing The outer working cylinder, inner sliding sleeve, and switching rod are subjected to quenching and tempering heat treatment: held at 820-860℃ for 2-3 hours and cooled by oil cooling to improve their mechanical strength, wear resistance, and corrosion resistance.

[0028] S4: Anti-corrosion treatment The joint, outer working cylinder, lower joint, inner sliding sleeve, switching rod, air injection pipe and air outlet pipe are chrome-plated or phosphated to enhance corrosion resistance.

[0029] S5: Assembly and Debugging Install the sealing ring in the annular groove of the inner sliding sleeve, assemble the air injection pipe to the corresponding position on the upper part of the inner sliding sleeve, and install the air outlet pipe and its matching valve body on the lower part of the inner sliding sleeve. Insert the inner sliding sleeve into the outer working cylinder to ensure that the inner sliding sleeve can slide smoothly up and down, and that the sealing ring can effectively seal the annular space between the inner sliding sleeve and the outer working cylinder. Connect the upper connector and lower connector to the outer working cylinder threadedly and tighten them in sequence, so that the annular stop surface of the upper connector corresponds to the top limiting shoulder of the inner sliding sleeve and the annular stop surface of the lower connector corresponds to the bottom limiting shoulder of the inner sliding sleeve, so as to ensure the accurate position of the upper and lower stop points of the inner sliding sleeve. Install a fixed air lift valve on the reserved structure of the air intake channel; Debugging and verification: The inner sliding sleeve is switched between the upper and lower dead points by the switching rod to check the channel connectivity in the two working states. In the chamber-type air lift mode, it is found that the upper flow channel hole is connected to the upper air inlet hole, and in the continuous flow air lift mode, it is found that the lower flow channel hole is connected to the annular cavity. The switching rod is stored independently as a supporting component and is used to drive the inner sliding sleeve to switch working states during subsequent operations.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention, through the design of a sliding inner sleeve structure and a matching switching rod, enables a single device to flexibly and reliably switch between continuous flow gas lift and chamber gas lift modes. This effectively solves the problem described in the background art that existing gas lift tools have limited functionality and cannot simultaneously achieve stable production in high-yield wells and efficient lifting in low-yield wells. When it is necessary to switch from continuous flow mode to chamber mode (suitable for low-yield wells), the switching rod is thrown or lowered. The flat impact head at the bottom of the rod impacts the limiting shoulder at the top of the inner sleeve under the action of gravity or external force, driving the inner sleeve to slide down along the inner wall of the outer working cylinder until the lower stop point (i.e., the bottom annular force-bearing shoulder abuts against the lower connector). At this time, the lower flow channel hole on the side wall of the inner sleeve is blocked by the inner wall of the outer working cylinder, while the upper flow channel hole is precisely aligned and connected with the upper air inlet hole of the air inlet channel. High-pressure gas is then injected directly into the upper part of the central flow channel through the injection hole, upper air inlet hole, and upper flow channel hole, rapidly lifting the fluid accumulated below the device and achieving efficient intermittent drainage, which is particularly suitable for low-yield wells. 2. When switching to continuous flow mode (suitable for high-yield wells), the switching rod impacts and drives the inner sliding sleeve to slide upward to the upper stop point (the top limit shoulder abuts against the lower end of the upper connector). At this time, the upper flow channel hole is blocked by the inner wall of the outer working cylinder, while the lower flow channel hole is connected to the lower annular cavity. The high-pressure gas then enters the annular cavity through the lower air inlet hole, and is then continuously and stably injected into the fluid flowing in the central flow channel through the lower flow channel hole, reducing the fluid density and achieving a smooth and continuous lift. The sealing ring on the central plate ensures the sealing of the annulus during the sliding process and prevents gas leakage. 3. This scheme can change the airflow path by sliding the inner sleeve in a straight line. The mode switching operation is simple and quick. Only one switching rod needs to be thrown. There is no need to remove the tubing string or change tools, which greatly improves the efficiency and adaptability of operation. The device can optimize the lifting mode in real time according to the changes in oil well production capacity. It can maintain continuous and stable production in high-production wells and give full play to the high efficiency of fluid drainage of chamber gas lift in low-production wells. It significantly expands the application scope of gas lift technology and improves recovery rate and economic benefits. Attached Figure Description

[0031] Figure 1 The diagram shown is a three-dimensional structural schematic of the present invention; Figure 2 The diagram shown is a three-dimensional cross-sectional view of the inner sliding sleeve of the present invention. Figure 3 The diagram shown is a cross-sectional perspective view of the overall structure of the present invention. Figure 4 The diagram shows a three-dimensional structure of the upper flow channel hole, lower flow channel hole, and sealing ring of the present invention. Figure 5The diagram shown is a three-dimensional structural schematic of the switching rod of the present invention; Figure 6 The diagram shown is a plan view of the inner sliding sleeve of the present invention.

[0032] Reference numerals: 1. Upper connector; 101. Air injection port; 2. Outer working cylinder; 3. Lower connector; 4. Inner sliding sleeve; 5. Central flow channel; 6. Upper annular cavity; 61. Lower annular cavity; 62. Air injection pipe; 7. Air inlet channel; 71. Upper air inlet; 72. Lower air inlet; 8. Upper flow channel hole; 9. Lower flow channel hole; 10. Sealing ring; 11. Annular force-bearing shoulder; 12. Switching rod; 121. Metal rod; 122. Arc-shaped guide head; 123. Planar impact head; 13. Air outlet pipe; 14. Valve body. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To address the issue that existing gas lift tools have limited functionality and cannot simultaneously achieve stable production in high-yield wells and efficient lifting in low-yield wells, the following technical solution is proposed. Please refer to [link / reference]. Figures 1-6 ; A composite air lift device and its manufacturing method include: The upper connector 1, outer working cylinder 2, and lower connector 3 are fixedly connected in sequence from top to bottom; The outer working cylinder 2 is provided with an inner sliding sleeve 4 that can slide up and down. The inner sliding sleeve 4 forms a central flow channel 5, an upper annular cavity 6, and a lower annular cavity 61. At least one set of air inlet channels 7 are provided on the side wall of the outer working cylinder 2. The air inlet channels 7 are provided with an upper air inlet hole 71 and a lower air inlet hole 72. An air injection hole 101 communicating with the air inlet channel 7 is provided through the upper end of the upper connector 1. The inner sliding sleeve 4 has two sets of flow channel holes on its side wall, namely the upper flow channel hole 8 and the lower flow channel hole 9. A central disc is fixed to the outer wall of the inner sliding sleeve 4, and a sealing ring 10 is fixed to the side wall of the central disc. The sealing ring 10 is used to seal the annular space between the inner sliding sleeve 4 and the outer working cylinder 2. The inner sliding sleeve 4 has a limiting shoulder at the top and an annular force-bearing shoulder 11 at the bottom for limiting. The inner sliding sleeve 4 slides upward until its top limiting shoulder abuts against the lower end of the upper connector 1, which is the upper stop point. The inner sliding sleeve 4 slides downward until its bottom annular force-bearing shoulder 11 abuts against the lower connector 3 or is blocked by the lower connector 3, which is the lower stop point. It also includes a switching rod 12 for driving the inner sliding sleeve 4 to slide up and down. The switching rod 12 is a long strip metal rod 121 with an arc-shaped guide head 122 at the top and a flat impact head 123 at the bottom. The limiting shoulder at the top of the inner sliding sleeve 4 is adapted to the flat impact head 123. An air outlet pipe 13 is provided at the lower part of the inner sliding sleeve 4; The device has two operating states: The first working state is the chamber-type gas lift mode: when the inner sleeve 4 is at the lower dead point, the lower flow channel hole 9 is blocked by the inner wall of the outer working cylinder 2. At this time, the upper flow channel hole 8 is connected to the upper air inlet hole 71 on the outer working cylinder 2. The high-pressure gas enters the upper part of the central flow channel 5 through the air inlet channel 7, the upper air inlet hole 71, and the upper flow channel hole 8, and then flows out from the outlet pipe 13 through the central flow channel 5, which is used to lift the liquid in the outer working cylinder 2. The second working state is the continuous flow air lift mode: when the inner sliding sleeve 4 is at the upper dead point, the upper flow channel hole 8 is blocked by the inner wall of the outer working cylinder 2, and the lower flow channel hole 9 is connected to the lower annular cavity 61. At this time, the high pressure gas enters the lower annular cavity 61 through the air inlet channel 7 and the lower air inlet hole 72, and then is injected into the fluid in the central flow channel 5 through the lower flow channel hole 9. Finally, it flows out from the air outlet pipe 13 through the central flow channel 5, which is used to lift the liquid in the outer working cylinder 2.

[0035] In this embodiment, specifically, the side wall of the annular force-bearing shoulder 11 and the inner wall of the outer working cylinder 2 are fitted together.

[0036] In this embodiment, specifically, both the upper connector 1 and the lower connector 3 are nut-shaped structures.

[0037] In this embodiment, specifically, at least two central flow channels 5 are provided.

[0038] In this embodiment, specifically, the radius of curvature of the arc-shaped guide head 122 of the switching rod 12 is 5-10mm, the flatness of the end face of the planar impact head 123 is not greater than 0.05mm, and the diameter of the planar impact head 123 is not less than the inner diameter of the annular force-bearing shoulder 11 at the top of the inner sliding sleeve 4.

[0039] In this embodiment, specifically, the center of the upper flow channel hole 8 and the center of the lower flow channel hole 9 are located on the same vertical line.

[0040] In this embodiment, specifically, a fixed air lift valve is connected to the air inlet channel 7 on the outer working cylinder 2.

[0041] In this embodiment, specifically, a valve body 14 is provided on the air outlet pipe 13.

[0042] In this embodiment, specifically, the upper inner wall of the inner sleeve 4 is provided with an air injection pipe 62 for air intake. The air injection pipe 62 and the upper flow channel hole 8 are interconnected inside the inner sleeve 4. When the air injection pipe 62 is interconnected with the upper air inlet hole 71, the upper flow channel hole 8 and the lower flow channel hole 9 are both blocked by the inner wall of the outer working cylinder 2.

[0043] The present invention also provides a method for manufacturing a composite air lift device, the method comprising the following steps: S1: Machining basic components Machining of upper connector 1, lower connector 3, and outer working cylinder 2 respectively; Internal threads are machined on the inner walls of the upper connector 1 and the lower connector 3, and external threads are machined on the outer walls. An air injection hole 101 communicating with the air intake channel 7 is machined through the upper end of the upper connector 1. At least one set of air intake channels 7 are machined on the side wall of the outer working cylinder 2. The air intake channels 7 need to be formed with upper air intake hole 71 and lower air intake hole 72, and a connection structure for connecting with the fixed air lift valve is reserved.

[0044] S2: Processing core functional components Machining of inner sleeve 4: The center flow channel 5, the upper annular cavity 6, and the lower annular cavity 61 are machined inside the cylindrical blank. The annular groove for installing the sealing ring 10 is machined on its outer wall, and the upper flow channel hole 8 and the lower flow channel hole 9 are machined on the side wall to ensure that the centers of the upper flow channel hole 8 and the lower flow channel hole 9 are on the same vertical line. A limiting shoulder and annular force-bearing shoulder 11 are machined at the top to ensure that the sidewalls of the limiting shoulder and annular force-bearing shoulder 11 can fit against the inner wall of the outer working cylinder 2. The installation structure of the gas injection pipe 62 is processed on the upper inner wall to ensure that the gas injection pipe 62 and the upper flow channel hole 8 are internally interconnected, and when the gas injection pipe 62 is connected to the upper air inlet hole 71, both the upper and lower flow channel holes can be blocked by the inner wall of the outer working cylinder 2. The assembly interface of the air pipe 13 is machined at the bottom.

[0045] Processing of switching rod 12: The long strip rod 121 is made of metal material, and its length is adapted to the well depth, while its diameter is smaller than the inner diameter of the production tubing. A circular arc-shaped guide head 122 is machined at the top of the rod 121, and a flat impact head 123 is machined at the bottom. The diameter is not less than the inner diameter of the annular force-bearing shoulder 11 at the top of the inner sliding sleeve 4, and the end face roughness Ra≤1.6μm.

[0046] S3: Enhancement Processing The outer working cylinder 2, inner sliding sleeve 4, and switching rod 12 are subjected to quenching and tempering heat treatment: held at 820-860℃ for 2-3 hours and cooled by oil cooling to improve their mechanical strength, wear resistance, and corrosion resistance.

[0047] S4: Anti-corrosion treatment The joint 1, outer working cylinder 2, lower joint 3, inner sliding sleeve 4, switching rod 12, air injection pipe 62, and air outlet pipe 13 are chrome-plated or phosphated to enhance corrosion resistance.

[0048] S5: Assembly and Debugging Install the sealing ring 10 in the annular groove of the inner sliding sleeve 4, assemble the air injection pipe 62 to the corresponding position on the upper part of the inner sliding sleeve 4, and install the air outlet pipe 13 and its matching valve body 14 on the lower part of the inner sliding sleeve 4. Insert the inner sliding sleeve 4 into the outer working cylinder 2 to ensure that the inner sliding sleeve 4 can slide smoothly up and down, and that the sealing ring 10 can effectively seal the annular space between the inner sliding sleeve 4 and the outer working cylinder 2. Connect the upper connector 1 and the lower connector 3 to the outer working cylinder 2 in sequence and tighten them so that the annular stop surface of the upper connector 1 corresponds to the top limiting shoulder of the inner sliding sleeve 4 and the annular stop surface of the lower connector 3 corresponds to the bottom limiting shoulder of the inner sliding sleeve 4, so as to ensure that the upper and lower stop points of the inner sliding sleeve 4 are accurately positioned. A fixed air lift valve is installed on the reserved structure of the air intake channel 7; Debugging and verification: Drive the inner sliding sleeve 4 between the upper and lower dead points by switching rod 12 to check the channel connectivity in the two working states. Check whether the upper flow channel hole 8 is connected to the upper air inlet hole 71 in the chamber air lift mode, and whether the lower flow channel hole 9 is connected to the annular cavity 6 in the continuous flow air lift mode. The switching rod 12 is stored independently as a supporting component and is used to drive the inner sliding sleeve 4 to switch working states during subsequent operations.

[0049] Working Principle: When this composite gas lift device is in operation, the position of the inner sliding sleeve 4 inside the outer working cylinder 2 needs to be adjusted by the matching switching rod 12 to achieve precise switching between chamber gas lift mode and continuous flow gas lift mode. The device is first fixedly connected to the external production tubing through the upper connector 1 and the lower connector 3. The outer working cylinder 2 provides a stable sliding support space for the inner sliding sleeve 4. The sealing ring 10 on the central plate of the outer wall of the inner sliding sleeve 4 can effectively seal the annulus between the inner sliding sleeve 4 and the outer working cylinder 2 to prevent gas or liquid leakage during operation. When the chamber gas lift mode needs to be activated, the operator lowers the switching rod 12 through the tubing, so that the planar impact head 123 of the switching rod 12 makes precise contact with the limiting shoulder at the top of the inner sliding sleeve 4 and applies a downward force, driving the inner sliding sleeve 4 to slide downward along the inner wall of the outer working cylinder 2. Until the annular force-bearing shoulder 11 at the bottom of the inner sliding sleeve 4 abuts against the lower connector 3, that is, the inner sliding sleeve 4 is at the lower stop point. At this time, the lower flow channel hole 9 of the inner sliding sleeve 4 is completely blocked by the inner wall of the outer working cylinder 2, while the upper flow channel hole 8 is precisely connected to the upper air inlet hole 71 of the upper air inlet channel 7 of the outer working cylinder 2. The high-pressure gas enters the air inlet channel 7 through the air injection hole 101 of the upper connector 1, and then enters the upper part of the central flow channel 5 of the inner sliding sleeve 4 through the upper air inlet hole 71 and the upper flow channel hole 8 in sequence. Then the high-pressure gas flows downward along the central flow channel 5 and finally flows out from the air outlet pipe 13 at the bottom of the inner sliding sleeve 4. The valve body 14 on the air outlet pipe 13 can adjust the fluid output according to actual needs. The high-pressure gas is fully mixed with the liquid in the outer working cylinder 2 during the flow process, and the liquid is transported upward by the lifting force of the gas to realize the chamber-type air lift function. When switching to continuous flow air lift mode, the operator lifts the switching rod 12 through the tubing column, so that the flat impact head 123 of the switching rod 12 contacts the limiting shoulder at the top of the inner sliding sleeve 4 again and applies an upward force, driving the inner sliding sleeve 4 to slide upward along the inner wall of the outer working cylinder 2 until the limiting shoulder at the top of the inner sliding sleeve 4 abuts against the lower end of the upper connector 1, that is, the inner sliding sleeve 4 is at the upper stop point. At this time, the upper flow channel hole 8 of the inner sliding sleeve 4 is blocked by the inner wall of the outer working cylinder 2, while the lower flow channel hole 9 is connected to the upper annular cavity 6 of the inner sliding sleeve 4. The high pressure gas enters the air intake channel 7 through the air injection hole 101 of the upper connector 1, and then enters the upper annular cavity 6 of the inner sliding sleeve 4 through the lower air intake hole 72 of the air intake channel 7. Subsequently, the high-pressure gas is injected into the fluid in the central channel 5 of the inner sliding sleeve 4 through the lower flow channel hole 9, forming a continuous gas-liquid mixture with the fluid. The mixture flows downward along the central flow channel 5 and is discharged from the outlet pipe 13, realizing the continuous flow air lift function. Furthermore, when the inner sliding sleeve 4 is in a specific adjustment position so that the gas injection pipe 62 is interconnected with the upper air inlet 71, the upper flow channel hole 8 and the lower flow channel hole 9 of the inner sliding sleeve 4 are blocked by the inner wall of the outer working cylinder 2, which can realize the temporary gas cut-off or pressure regulation state of the device. The fixed gas lift valve connected to the air inlet channel 7 of the outer working cylinder 2 can stably control the air inlet pressure. The lower annular cavity 61 inside the inner sliding sleeve 4 assists in fluid diversion. The long strip metal rod 121 of the switching rod 12 can be adapted to the length according to the well depth. The arc-shaped guide head 122 at the top facilitates its smooth movement in the tubing string, ensuring that the switching position of the inner sliding sleeve 4 is accurate and reliable. The entire device achieves stable switching between the two gas lift modes and efficient gas lift operation through the coordinated action of various components.

[0050] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A composite air lift device, characterized in that, include: The upper connector (1), outer working cylinder (2) and lower connector (3) are fixedly connected from top to bottom. The outer working cylinder (2) is provided with an inner sliding sleeve (4) that can slide up and down. The inner sliding sleeve (4) forms a central flow channel (5), an upper annular cavity (6) and a lower annular cavity (61). At least one set of air inlet channels (7) are opened on the side wall of the outer working cylinder (2). The air inlet channels (7) are provided with an upper air inlet hole (71) and a lower air inlet hole (72). The upper end of the upper connector (1) is provided with an air injection hole (101) that communicates with the air inlet channel (7). The inner sleeve (4) has two sets of flow channel holes on its side wall, namely the upper flow channel hole (8) and the lower flow channel hole (9). The inner sliding sleeve (4) has a central disk fixed to its outer wall, and a sealing ring (10) is fixed to the side wall of the central disk. The sealing ring (10) is used to seal the annular space between the inner sliding sleeve (4) and the outer working cylinder (2). The inner sliding sleeve (4) has a limiting shoulder at the top and an annular force-bearing shoulder (11) at the bottom for limiting. The upper stop point is the position where the inner sliding sleeve (4) slides upward to the position where its top limiting shoulder abuts against the lower end of the upper connector (1), and the lower stop point is the position where the inner sliding sleeve (4) slides downward to the position where its bottom annular force-bearing shoulder (11) abuts against the lower connector (3) or is blocked by the lower connector (3). It also includes a switching rod (12) for driving the inner sliding sleeve (4) to slide up and down. The switching rod (12) is a long strip metal rod (121) with an arc-shaped guide head (122) at the top and a flat impact head (123) at the bottom. The limiting shoulder at the top of the inner sliding sleeve (4) is adapted to the flat impact head (123). An air outlet pipe (13) is provided at the lower part of the inner sliding sleeve (4); The device has two operating states: The first working state is the chamber-type gas lift mode: when the inner sleeve (4) is at the lower stop point, the lower flow channel hole (9) is blocked by the inner wall of the outer working cylinder (2). At this time, the upper flow channel hole (8) is connected to the upper air inlet hole (71) on the outer working cylinder (2). The high pressure gas enters the upper part of the central flow channel (5) through the air inlet channel (7), the upper air inlet hole (71) and the upper flow channel hole (8), and then flows out from the outlet pipe (13) through the central flow channel (5) to lift the liquid in the outer working cylinder (2). The second working state is the continuous flow air lift mode: when the inner sleeve (4) is at the top dead center, the upper flow channel hole (8) is blocked by the inner wall of the outer working cylinder (2), and the lower flow channel hole (9) is connected to the lower annular cavity (61). At this time, the high pressure gas enters the lower annular cavity (61) through the air inlet channel (7) and the lower air inlet hole (72), and then is injected into the fluid in the central flow channel (5) through the lower flow channel hole (9). Finally, it flows out from the outlet pipe (13) through the central flow channel (5) to lift the liquid in the outer working cylinder (2).

2. The composite air lift device according to claim 1, characterized in that, The side wall of the annular load-bearing shoulder (11) is attached to the inner wall of the outer working cylinder (2).

3. The composite air lift device according to claim 1, characterized in that, Both the upper connector (1) and the lower connector (3) are nut-shaped structures.

4. The composite air lift device according to claim 1, characterized in that, The central flow channel (5) has at least two.

5. The composite air lift device according to claim 1, characterized in that, The arc-shaped guide head (122) of the switching rod (12) has a radius of curvature of 5-10mm, the flatness of the end face of the planar impact head (123) is not greater than 0.05mm, and the diameter of the planar impact head (123) is not less than the inner diameter of the annular force-bearing shoulder (11) at the top of the inner sliding sleeve (4).

6. The composite air lift device according to claim 1, characterized in that, The center of the upper flow channel hole (8) and the center of the lower flow channel hole (9) are located on the same vertical line.

7. The composite air lift device according to claim 1, characterized in that, A fixed air lift valve is connected to the air inlet channel (7) on the outer working cylinder (2).

8. The composite air lift device according to claim 1, characterized in that, A valve body (14) is provided on the air outlet pipe (13).

9. The composite air lift device according to claim 1, characterized in that, The inner wall of the upper part of the inner sleeve (4) is provided with an air injection pipe (62) for air intake. The air injection pipe (62) and the upper flow channel hole (8) are interconnected inside the inner sleeve (4). When the air injection pipe (62) is interconnected with the upper air inlet hole (71), the upper flow channel hole (8) and the lower flow channel hole (9) are both blocked by the inner wall of the outer working cylinder (2).

10. A method for manufacturing a composite air lift device, characterized in that, Includes the following steps: S1: Machining basic components The upper connector (1), lower connector (3) and outer working cylinder (2) are machined respectively. Internal threads are machined on the inner walls of the upper connector (1) and the lower connector (3), and external threads are machined on the outer walls. An air injection hole (101) communicating with the air intake channel (7) is machined through the upper end of the upper connector (1). At least one set of air intake channels (7) are machined on the side wall of the outer working cylinder (2). The air intake channels (7) need to be formed with an upper air intake hole (71) and a lower air intake hole (72), and a connection structure for a fixed air lift valve is reserved. S2: Processing core functional components Machining of the inner sliding sleeve (4): The center flow channel (5), the upper annular cavity (6) and the lower annular cavity (61) are machined inside the cylindrical blank. The annular groove for installing the sealing ring (10) is machined on its outer wall, and the upper flow channel hole (8) and the lower flow channel hole (9) are machined on the side wall to ensure that the centers of the upper flow channel hole (8) and the lower flow channel hole (9) are on the same vertical line; A limiting shoulder and an annular force-bearing shoulder (11) are machined at the top to ensure that the sidewalls of the limiting shoulder and the annular force-bearing shoulder (11) can fit against the inner wall of the outer working cylinder (2); The installation structure of the gas injection pipe (62) is processed on the upper inner wall to ensure that the gas injection pipe (62) and the upper flow channel hole (8) are internally interconnected, and when the gas injection pipe (62) is connected to the upper air inlet hole (71), the upper and lower flow channel holes can be blocked by the inner wall of the outer working cylinder (2). The assembly interface of the vent pipe (13) is machined at the bottom; Processing of switching rod (12): The long strip rod (121) is made of metal material, and its length is adapted to the well depth, while its diameter is smaller than the inner diameter of the production tubing. A circular arc guide head (122) is machined at the top of the rod (121), and a flat impact head (123) is machined at the bottom. The diameter is not less than the inner diameter of the annular force-bearing shoulder (11) at the top of the inner sleeve (4), and the end face roughness Ra≤1.6μm. S3: Enhancement Processing The outer working cylinder (2), inner sliding sleeve (4) and switching rod (12) are subjected to quenching and tempering heat treatment: held at 820-860℃ for 2-3 hours and cooled by oil cooling to improve their mechanical strength, wear resistance and corrosion resistance. S4: Anti-corrosion treatment The joint (1), outer working cylinder (2), lower joint (3), inner sliding sleeve (4), switching rod (12), air injection pipe (62), and air outlet pipe (13) are chrome-plated or phosphated to enhance corrosion resistance. S5: Assembly and Debugging Install the sealing ring (10) in the annular groove of the inner sliding sleeve (4), assemble the air injection pipe (62) to the corresponding position on the upper part of the inner sliding sleeve (4), and install the air outlet pipe (13) and its matching valve body (14) on the lower part of the inner sliding sleeve (4). Insert the inner sliding sleeve (4) into the outer working cylinder (2) to ensure that the inner sliding sleeve (4) can slide smoothly up and down, and that the sealing ring (10) can effectively seal the annular space between the inner sliding sleeve (4) and the outer working cylinder (2); Connect the upper connector (1) and lower connector (3) to the outer working cylinder (2) in sequence and tighten them so that the annular stop surface of the upper connector (1) corresponds to the top limiting shoulder of the inner sliding sleeve (4) and the annular stop surface of the lower connector (3) corresponds to the bottom limiting shoulder of the inner sliding sleeve (4), so as to ensure that the upper and lower stops of the inner sliding sleeve (4) are accurately positioned. A fixed air lift valve is installed on the reserved structure of the air intake channel (7); Debugging and verification: Drive the inner sliding sleeve (4) between the upper and lower stops by switching bar (12) to check the channel connectivity in the two working states. In the chamber-type air lift mode, whether the upper flow channel hole (8) is connected to the upper air inlet hole (71) and in the continuous flow air lift mode, whether the lower flow channel hole (9) is connected to the annular cavity (6). The switching rod (12) is stored independently as a supporting component and is used to drive the inner sliding sleeve (4) to switch working states during subsequent operations.

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