Gas well drainage gas recovery control device and method with switching function

Abstract

The invention relates to the field of gas field development, in particular to a gas well drainage gas recovery control device and method with a switching function. Comprising an upper connector, a lower connector, an outer sleeve, a gas lift control valve, a central pipe and a U-shaped pipe. The outer sleeve is arranged between the upper connector and the lower connector and fixedly connected with the upper connector and the lower connector in a sealed mode. The lower joint is provided with an air inlet hole for communicating the outside and the inside cavity of the device, and the gas lift control valve is arranged in the air inlet hole; when the gas lift pressure exceeds the pre-pressure, the gas lift control valve is opened, injected gas enters the inner cavity of the device through the gas inlet and is mixed with accumulated liquid in the oil pipe, and the accumulated liquid is lifted. A plurality of control devices are connected in series in a gas well oil pipe to form a multi-stage independent cavity, the pre-pressure of each stage of device is gradually reduced from top to bottom, each stage of device is sequentially opened and closed by adjusting the gas lift pressure step by step, accumulated liquid in the deep position of a gas well can be effectively lifted even under the low gas lift pressure, and the safety of the gas well is improved. The problem that the yield is affected by later-stage liquid accumulation of a gas well is solved.

Description

Technical Field

[0001] This invention relates to the field of gas field development, and specifically to a gas well drainage and gas production control device and method with switching function. Background Technology

[0002] As shale gas fields enter the mid-to-late stages of development, the formation energy and pressure of gas wells continue to decline, resulting in an increasing number of wells unable to produce naturally. Insufficient formation energy in gas wells easily leads to fluid accumulation at the bottom of the well, which not only reduces gas well production but can also cause well shutdowns in severe cases. Gas lift technology can restore and maintain the continued production of gas wells and has become an important technical means to solve the problem of fluid accumulation in gas wells.

[0003] However, traditional drop-and-reach or fixed gas lift valves have significant technical limitations. Injected gas struggles to effectively reach deep sections and horizontal segments of the gas well, requiring higher gas lift pressures to lift accumulated liquid. This not only increases energy consumption but also results in poor liquid lifting at deeper levels, severely impacting well production efficiency. To address this, a gas well drainage and production control device is proposed, which can effectively lift deep-seated liquid in the gas well even at lower gas lift pressures, restoring normal well production. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a gas well drainage and gas production control device and method with a switching function. By connecting multiple gas well drainage and gas production control devices in series, the gas well is made into a multi-level independent chamber, which lifts the accumulated liquid from top to bottom step by step. Even at a low gas lift pressure, it can effectively lift the accumulated liquid deep in the gas well.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a gas well drainage and gas production control device with switching function, characterized in that: it includes an upper connector, a lower connector, an outer sleeve, a gas lift control valve, a central pipe, and a U-shaped pipe; the outer sleeve is disposed between the upper connector and the lower connector, and is fixedly and sealed to the upper connector and the lower connector; the lower connector is provided with an air inlet hole connecting the outside of the device and the internal cavity, and the gas lift control valve is disposed in the air inlet hole; the central pipe is disposed inside the outer sleeve, and is fixedly and sealed to the upper connector; the opening of the U-shaped pipe faces upward, and is fixed below the central pipe by a connecting component; there are gaps between the pipe wall of the U-shaped pipe and the outer sleeve and the central pipe, forming two annular channels that are connected at the top, and the two annular channels are respectively connected to the lower connector and the central pipe.

[0006] According to the above technical solution, the air inlet includes a first channel and a second channel, the diameter of the second channel is larger than the diameter of the first channel, and the air lift control valve is disposed in the second channel.

[0007] According to the above technical solution, the air lift control valve includes a sealing ball, an elastic element, and a valve lock. The sealing ball is movably disposed in the second channel, the valve lock is fixed at the outlet of the second channel, and the two ends of the elastic element are respectively connected to the sealing ball and the valve lock.

[0008] According to the above technical solution, the diameter of the sealing ball is larger than the diameter of the first channel, the elastic element is in a compressed state, a pre-pressure is applied to the sealing ball, so that the sealing ball abuts against the outlet end of the first channel, and the air lift control valve is in a closed state.

[0009] According to the above technical solution, the outer sleeve is fixedly connected to the upper connector and the lower connector, and the upper connector is fixedly connected to the central tube by threads.

[0010] According to the above technical solution, the threaded connection is provided with at least one sealing ring.

[0011] According to the above technical solution, the connecting assembly includes a radial support and an axial connector. The radial support is fixed to the bottom surface of the central tube, and the two ends of the axial connector are respectively connected to the center of the radial support and the bottom of the U-shaped tube.

[0012] According to the above technical solution, the control method of the gas well drainage and gas production control device with switching function of the present invention is characterized by the following steps:

[0013] S1: Multiple gas well drainage and gas production control devices are installed in series at different depths of the gas well. In the early stage of gas well development, the gas well itself uses its own formation energy and pressure to produce gas flow.

[0014] S2: When the formation pressure of the gas well drops to the point where it cannot flow on its own, the gas lift pressure is applied to the gas well through the surface compressor. When the gas lift pressure exceeds the pre-pressure applied to the sealing ball by the elastic element in the first-stage gas well drainage and gas production control device, the gas lift pressure pushes the sealing ball upward. The injected gas enters the device through the air inlet and mixes with the accumulated liquid, reducing the fluid gradient and lifting the accumulated liquid in the first-stage device.

[0015] S3: Gradually reduce the surface gas lift pressure. When the gas lift pressure is lower than the pre-pressure of the first-stage gas well drainage and gas production control device, the first-stage gas well drainage and gas production control device is closed. The gas moves to the second-stage gas well drainage and gas production control device and opens it, lifting the accumulated liquid in the second-stage gas well drainage and gas production control device.

[0016] S4: Repeat step S3 to sequentially open and close the multi-stage gas well drainage and gas production control device, thereby achieving gas lift of liquid accumulation throughout the wellbore.

[0017] According to the above technical solution, the pre-pressure of the gas well drainage and gas production control device at each level decreases gradually from top to bottom.

[0018] The beneficial effects of this invention are:

[0019] 1. This invention applies pre-pressure to the sealing ball using an elastic element, keeping the gas lift control valve closed, with the inner U-shaped tube opening facing upwards to prevent backflow of accumulated liquid. When liquid accumulation in the gas well leads to reduced production, a gas lift pressure is applied to the well via a surface compressor. When the gas lift pressure exceeds the pre-pressure of the elastic element, the gas lift control valve automatically opens, injecting gas into the device to mix with the accumulated liquid, reducing the fluid gradient, achieving liquid lift, and improving gas well production efficiency.

[0020] 2. This invention involves arranging multiple gas well drainage and gas production control devices in series from top to bottom within the gas well tubing, forming multi-stage independent chambers. The pre-pressure of each stage of the gas well drainage and gas production control device decreases progressively from top to bottom. Initially, the gas lift pressure is controlled to be greater than the pre-pressure set in the gas lift control valve of the first-stage device, lifting the accumulated liquid inside. Then, the gas lift pressure is gradually reduced, allowing the injected gas to sequentially activate each stage of the device from top to bottom, gradually draining the accumulated liquid throughout the entire gas well. Even at lower gas lift pressures, the accumulated liquid deep within the gas well can be gradually lifted to the surface, restoring gas well production. Attached Figure Description

[0021] Figure 1 A schematic diagram of a gas well drainage and gas production control device with switching function provided in an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of a series connection of multiple gas well drainage and gas production control devices provided in an embodiment of the present invention;

[0023] In the diagram: 1. Upper connector; 2. Lower connector; 21. First channel; 22. Second channel; 3. Outer sleeve; 4. Gas lift control valve; 41. Sealing ball; 42. Spring; 43. Valve lock; 5. Central tube; 6. U-tube; 7. Sealing ring; 8. Radial support; 9. Axial connector; 10. Annular channel; 100. First-stage gas well drainage and gas production control device; 200. Second-stage gas well drainage and gas production control device; 300. Third-stage gas well drainage and gas production control device. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] like Figure 1 As shown, this invention provides a gas well drainage and gas production control device with a switching function, including an upper connector 1, a lower connector 2, an outer sleeve 3, a gas lift control valve 4, a central pipe 5, and a U-shaped pipe 6. The upper connector 1 and the lower connector 2 are respectively connected to the upper oil pipe and the lower oil pipe. The outer sleeve 3 is located between the upper connector 1 and the lower connector 2 and is fixedly and sealed to the upper connector 1 and the lower connector 2. The lower connector 2 is provided with an air inlet that connects the outside of the device to the internal cavity, and the gas lift control valve 4 is located in the air inlet. The central pipe 5 is located inside the outer sleeve 3 and is fixedly and sealed to the upper connector 1. The opening of the U-shaped pipe 6 faces upward and is fixed below the central pipe 5 by a connecting assembly to prevent backflow of accumulated liquid. There are gaps between the pipe wall of the U-shaped pipe 6 and the outer sleeve 3 and the central pipe 5, forming two annular channels 10 that are connected at the top. The two annular channels 10 are respectively connected to the lower connector 2 and the central pipe 5.

[0027] This device automatically adjusts the air pressure inside the device through the air lift control valve 4. When the external air lift pressure exceeds the pre-pressure of the elastic element on the sealing ball 41, the sealing ball 41 moves upward, opens the air inlet, and injects air into the device to mix with the accumulated liquid, reducing the gradient of the fluid in the tubing, replenishing the fluid with energy, and realizing the lifting of the fluid in downhole oil transportation; then the external air lift pressure is gradually reduced to less than the pre-pressure, the sealing ball 41 returns to its original position, and the air lift control valve 4 automatically closes.

[0028] In this embodiment, the upper connector 1 and the lower connector 2 are arranged opposite to each other and are respectively connected to the upper oil pipe and the lower oil pipe. The outer sleeve 3 is cylindrical and is fixedly connected to the upper connector 1 and the lower connector 2 by threads. At least one sealing ring is provided between the outer sleeve 3 and the opposing circumferential surfaces of the upper connector 1 and the lower connector 2. The lower connector 2 is provided with an air inlet that connects the outside of the device to the internal cavity. The air inlet includes a first channel 21 and a second channel 22. The first channel 21 connects to the outside of the device, and the second channel 22 connects to the internal cavity. The diameter of the second channel 22 is larger than the diameter of the first channel 21. An air lift control valve 4 is provided in the second channel 22.

[0029] In this embodiment, the air lift control valve 4 includes a sealing ball 41, an elastic element, and a valve lock 43. The sealing ball 41 is movably disposed in the second channel 22, and the diameter of the sealing ball 41 is larger than the diameter of the first channel 21. The valve lock 43 is fixed at the outlet of the second channel 22. The elastic element is specifically a spring 42, one end of which is connected to the valve lock 43, and the other end is connected to the sealing ball 41. When the spring 42 is in a compressed state, one end abuts against the valve lock 43 and remains stationary, while the other end applies pre-pressure to the sealing ball 41, so that the sealing ball 41 tightly abuts against the first channel 21, and the entire air lift control valve 4 is in a closed state.

[0030] In this embodiment, the central tube 5 is disposed inside the outer sleeve 3. The central tube 5 is fixedly connected to the upper connector 1 by threads. At least one sealing ring 7 is provided between the opposing circumferential surfaces of the central tube 5 and the upper connector 1. A U-shaped tube 6 is fixed to the bottom of the central tube 5 by a connecting assembly. The connecting assembly includes a radial support 8 and an axial connector 9. The radial support 8 is cross-shaped and fixed to the bottom end face of the central tube 5. The axial connector 9 is vertically arranged, with one end fixed to the cross intersection of the radial support 8 and the other end fixed to the bottom of the U-shaped tube 6. The opening of the U-shaped tube 6 faces upward to prevent backflow of accumulated liquid. There are gaps between the tube wall of the U-shaped tube 6 and the outer sleeve 3 and the central tube 5, forming two annular channels 10 that are connected at the top. The two annular channels 10 are respectively connected to the lower connector 2 and the central tube 5.

[0031] In this embodiment, when the gas well is unable to produce gas normally due to accumulated liquid, gas is injected into the gas well through a surface compressor to increase the gas lift pressure inside the well. When the gas lift pressure is greater than the pre-pressure applied by the spring 42 to the sealing ball 41 inside the gas lift control valve 4, the injected gas pushes the sealing ball 41 upward, opening the gas lift control valve 4. The injected gas enters the internal cavity of the device through the air inlet, mixes with the accumulated liquid in the tubing, reduces the fluid gradient in the tubing, replenishes the fluid with energy, and achieves fluid lift in downhole oil transportation. When the accumulated liquid is discharged and the gas well resumes normal gas production, the pressure of the injected gas is reduced so that the gas lift pressure is less than the pre-pressure of the gas lift control valve 4 inside the device. At this time, the spring 42 pushes the sealing ball 41 against the air inlet, and the gas lift control valve 4 automatically closes. This device can automatically open or close the gas lift control valve 4 by adjusting the pressure of the injected gas.

[0032] like Figure 2 As shown, the present invention provides a control method for a gas well drainage and gas production control device with switching function, the specific steps of which are as follows:

[0033] S1: In the early stages of gas well development, the gas well itself utilizes formation energy and pressure to produce flowing gas.

[0034] S2: When the formation pressure of the gas well drops to the point where it cannot flow on its own, the gas lift pressure is applied to the gas well by the ground compressor. The gas lift pressure exceeds the pre-pressure applied to the sealing ball 41 by the elastic element in the first-stage gas well drainage and gas production control device 100. The sealing ball 41 moves upward, opens the air inlet, and injects gas into the device to mix with the accumulated liquid, reducing the fluid gradient and lifting the accumulated liquid in the first-stage device.

[0035] S3: Gradually reduce the surface gas lift pressure. When the gas lift pressure is lower than the pre-pressure of the first-stage gas well drainage and gas production control device 100, the first-stage gas well drainage and gas production control device 100 is closed, and the gas moves to the second-stage gas well drainage and gas production control device 200 and opens it, lifting the accumulated liquid in the second-stage gas well drainage and gas production control device 200.

[0036] S4: Repeat step S3 to sequentially open and close the multi-stage gas well drainage and gas production control device, thereby achieving gas lift of liquid accumulation throughout the wellbore.

[0037] In this embodiment, multiple gas well drainage and gas production control devices can be used in series, making the entire tubing form a multi-level independent chamber. For example... Figure 2 As shown, from top to bottom, there are a first-stage gas well drainage and gas production control device 100, a second-stage gas well drainage and gas production control device 200, and a third-stage gas well drainage and gas production control device 300. The pre-pressure of each stage of the gas well drainage and gas production control device decreases from top to bottom.

[0038] In this embodiment, during the initial stage of gas well development, the gas well itself utilizes formation energy and pressure for self-flowing production. When the formation pressure of the gas well drops to the point where it can no longer flow, a gas lift pressure is applied to the gas well through a surface compressor. Initially, the gas lift pressure is relatively high, exceeding the pre-pressure applied to the sealing ball 41 by the elastic element in the first-stage gas well drainage and gas production control device 100. The injected gas pushes the sealing ball 41 upward, opening the gas lift control valve 4. The injected gas enters the internal cavity of the device through the air inlet, mixes with the accumulated liquid in the tubing, reduces the gradient of the fluid in the tubing, replenishes the fluid with energy, and realizes the lifting of the fluid in downhole oil transportation.

[0039] In this embodiment, after the accumulated liquid in the first-stage gas well drainage and gas production control device 100 is drained, the gas lift pressure of the surface-injected gas is gradually reduced. When the gas lift pressure is lower than the pre-pressure of the first-stage gas well drainage and gas production control device 100, the first-stage gas well drainage and gas production control device 100 automatically closes, and the gas flows downward to the second-stage gas well drainage and gas production control device 200, opening its gas lift control valve 4 to lift the accumulated liquid in the second-stage gas well drainage and gas production control device 200. Then, the gas lift pressure of the surface-injected gas continues to decrease, the second-stage gas well drainage and gas production control device 200 automatically closes, and the third-stage gas well drainage and gas production control device 300 is opened. The opening and closing of the multi-stage gas well drainage and gas production control devices are realized sequentially downwards, achieving gas lift of the accumulated liquid in the entire wellbore.

[0040] In summary, by using a multi-stage gas well drainage and gas production control device in series, the problem of ground compressor air being unable to reach deep into the gas well is solved, and the gas pressure and volume required to lift the liquid are reduced. Even at a lower gas lift pressure, the accumulated liquid in the deep and horizontal sections of the gas well can be lifted to the surface step by step, thus enabling the gas well to resume production.

[0041] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A gas well drainage and gas production control device with switching function, characterized in that: It includes an upper connector, a lower connector, an outer sleeve, an air lift control valve, a central tube, and a U-shaped tube. The outer sleeve is located between the upper connector and the lower connector and is fixedly and sealed to them. The lower connector has an air inlet that connects the outside of the device to the internal cavity, and the air lift control valve is located inside the air inlet. The central tube is located inside the outer sleeve and is fixedly and sealed to the upper connector. The U-shaped tube has its opening facing upward and is fixed below the central tube by a connecting assembly. There are gaps between the wall of the U-shaped tube and both the outer sleeve and the central tube, forming two annular channels that connect at the top. The two annular channels are respectively connected to the lower connector and the central tube.

2. The gas well drainage and gas production control device with switching function according to claim 1, characterized in that: The air inlet includes a first channel and a second channel, the diameter of the second channel being larger than the diameter of the first channel, and the air lift control valve is disposed in the second channel.

3. A gas well drainage and gas production control device with switching function according to claim 2, characterized in that: The air lift control valve includes a sealing ball, an elastic element, and a valve lock. The sealing ball is movably disposed in the second channel, the valve lock is fixed at the outlet of the second channel, and the two ends of the elastic element are respectively connected to the sealing ball and the valve lock.

4. A gas well drainage and gas production control device with switching function according to claim 3, characterized in that: The diameter of the sealing ball is larger than the diameter of the first channel. The elastic element is in a compressed state, and a pre-pressure is applied to the sealing ball so that the sealing ball abuts against the outlet end of the first channel. The air lift control valve is in a closed state.

5. A gas well drainage and gas production control device with switching function according to claim 1, characterized in that: The outer sleeve is fixedly connected to the upper and lower connectors, and the upper connector is fixedly connected to the central tube by threads.

6. A gas well drainage and gas production control device with switching function according to claim 5, characterized in that: The threaded connection is provided with at least one sealing ring.

7. A gas well drainage and gas production control device with switching function according to claim 1, characterized in that: The connecting assembly includes a radial support and an axial connector. The radial support is fixed to the bottom surface of the central tube, and the two ends of the axial connector are respectively connected to the center of the radial support and the bottom of the U-shaped tube.

8. A control method for a gas well drainage and gas production control device with switching function according to any one of claims 1-7, characterized in that: Includes the following steps: S1: Multiple gas well drainage and gas production control devices are installed in series at different depths of the gas well. In the early stage of gas well development, the gas well itself uses its own formation energy and pressure to produce gas flow. S2: When the formation pressure of the gas well drops to the point where it cannot flow on its own, the gas lift pressure is applied to the gas well through the surface compressor. When the gas lift pressure exceeds the pre-pressure applied to the sealing ball by the elastic element in the first-stage gas well drainage and gas production control device, the gas lift pressure pushes the sealing ball upward. The injected gas enters the device through the air inlet and mixes with the accumulated liquid, reducing the fluid gradient and lifting the accumulated liquid in the first-stage device. S3: Gradually reduce the surface gas lift pressure. When the gas lift pressure is lower than the pre-pressure of the first-stage gas well drainage and gas production control device, the first-stage gas well drainage and gas production control device is closed. The gas moves to the second-stage gas well drainage and gas production control device and opens it, lifting the accumulated liquid in the second-stage gas well drainage and gas production control device. S4: Repeat step S3 to sequentially open and close the multi-stage gas well drainage and gas production control device, thereby achieving gas lift of liquid accumulation throughout the wellbore.

9. The control method for a gas well drainage and gas production control device with switching function according to claim 8, characterized in that: The pre-pressure of the gas well drainage and gas production control device at each level decreases progressively from top to bottom.

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