A flow restriction tool for preventing liquid fallback in a gas well bore

Abstract

The application discloses a gas well wellbore liquid fall-preventing throttling tool, which comprises a fishing head, a liquid fall-preventing throttling body, a sleeve, a liquid inlet cylinder, a connecting cylinder, a setting spring, a clamping sleeve, a sealing ring, a throttling channel, a liquid fall-preventing spiral flow channel, a setting clamp and a setting chamber. The device divides the inflowing gas-liquid fluid into two parts by the liquid fall-preventing throttling body, throttles, accelerates and depressurizes most of the fluid in the throttling channel, effectively prevents the liquid from falling back, and makes the other part of the fluid spiral upward along the liquid fall-preventing spiral flow channel. The asymmetric "narrowing-expanding" structure of the flow channel makes the forward resistance of the liquid smaller than the backward resistance, so that the liquid is less likely to fall back. The device is suitable for the water-gas well with insufficient gas liquid-carrying capacity, liquid fall or liquid accumulation in the wellbore, and can realize throttling, acceleration, pressure reduction, liquid fall prevention and improvement of the gas liquid-carrying capacity.

Description

A throttling device inside a gas wellbore to prevent liquid from flowing back. Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and to a tool used in the natural gas extraction process that can achieve throttling, speed increase, and pressure reduction, while preventing liquid backflow and improving the gas's liquid-carrying capacity, particularly a throttling tool for preventing liquid backflow inside a gas wellbore. Background Technology

[0002] In the process of gas reservoir development, insufficient water production in gas wells or insufficient formation energy can lead to insufficient gas-carrying capacity for liquid. As a result, the liquid carried by the gas falls back into the wellbore before it can be carried out of the wellhead. In addition, low-production gas wells have limited liquid-carrying capacity due to low gas flow rate, which can also cause liquid accumulation or water flooding in the wellbore. This problem is the main reason for the significant decline in gas well productivity and the reduction in gas well life.

[0003] Currently, the most common solutions to the above problems are drainage gas production technology or the installation of downhole choke technology to improve the gas-liquid carrying capacity. However, in actual application, it has been found that drainage gas production tools have insufficient choke effect and insignificant gas acceleration and pressure reduction effects during the drainage process. In addition, there is a significant accumulation of liquid in the wellbore upstream of the downhole choke during the use of the gas well.

[0004] Therefore, in view of the shortcomings of the above-mentioned drainage and gas production tools and gas well downhole throttling devices in application, the present invention provides a throttling tool in the gas wellbore that can prevent liquid backflow, which can achieve the purpose of throttling while preventing liquid backflow, thus achieving the purpose of drainage and gas production. Summary of the Invention

[0005] The purpose of this invention is to provide a device for current water-producing gas wells that can both drain and throttle, thereby achieving throttling, speed increase, and pressure reduction, while preventing liquid backflow and improving gas liquid carrying capacity, thereby increasing gas well production, extending gas well life, and improving recovery rate.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a throttling tool for preventing liquid backflow inside a gas well shaft, characterized in that it includes a retrieval head (1), a liquid backflow prevention throttling device (2), a sleeve (3), a liquid inlet cylinder (4), a connecting cylinder (5), a setting spring (6), a ferrule (7), a sealing ring (8), a throttling channel (201), a liquid backflow prevention spiral flow channel (202), a setting clamp (301), and a setting chamber (501). The retrieval head (1) has a central hole that is through it. The anti-liquid backflow throttling device (2) has a cylindrical structure and includes key components such as a throttling channel (201) and an anti-liquid backflow spiral flow channel (202). The throttling channel (201) has a symmetrical "expansion-contraction" form. The through hole formed by the "expansion-contraction" configuration of the throttling channel (201) is spherical or cup-shaped at the "expansion" configuration to prevent liquid backflow. The anti-liquid backflow spiral flow channel (202) has an asymmetrical "contraction-expansion" channel structure and is spirally distributed along the outer cylindrical surface of the anti-liquid backflow throttling device (2). The sleeve (3) has a cylindrical structure. The lower part of the inner wall of the sleeve (3) is provided with a setting head (301). The connecting cylinder (5) is cylindrical and has a through hole with the same diameter as the inner wall of the sleeve (3). The outer wall has a boss and groove with different diameters. The groove is provided at the upper part of the outer wall of the connecting cylinder (5). The groove has a concave cavity type setting chamber (501) inside the groove. The upper part of the sleeve (7) is cylindrical and the lower part is petal-shaped. The through hole formed by the connection of the retrieval head (1), the anti-liquid backflow throttling fluid (2), the liquid inlet cylinder (4), and the connecting cylinder (5) constitutes the central through hole of the throttling tool (0) in the gas well shaft that can prevent liquid backflow and can completely penetrate the entire structure.

[0007] Preferably, the retrieval head (1) and the anti-liquid backflow throttling device (2) are integral components. The upper end face of the throttling channel (201) is connected to the lower end face of the central hole of the retrieval head (1) and is coaxial, serving as the main flow channel for the fluid. The lower end face of the anti-liquid backflow throttling device (2) is provided with an internal thread, which is located between the throttling channel (201) and the anti-liquid backflow spiral flow channel (202). The upper end of the liquid inlet cylinder (4) is provided with an external thread, and the lower end internal thread of the anti-liquid backflow throttling device (2) is screwed into the upper end external thread of the liquid inlet cylinder (4), ensuring that the anti-liquid backflow throttling device (2) and the liquid inlet cylinder (4) are connected while forming a through hole.

[0008] Preferably, the outer wall of the sleeve (3) is completely fitted with the inner wall of the gas well shaft, and the upper part of the inner wall of the sleeve (3) is fitted with the outer wall of the anti-liquid backflow throttling fluid (2), ensuring that the fluid to be flowed can advance along the flow groove of the anti-liquid backflow spiral flow channel (202). There is a certain gap between the middle part of the inner wall of the sleeve (3) and the outer wall of the inlet cylinder (4), so that a part of the fluid advances along the through hole of the inlet cylinder (4) and the anti-liquid backflow throttling fluid (2), and another part enters the gap between the middle part of the inner wall of the sleeve (3) and the outer wall of the inlet cylinder (4) through the side wall hole of the inlet cylinder (4), and enters the anti-liquid backflow spiral flow channel (202) along the gap.

[0009] Preferably, the connection between the sleeve (3) and the connecting cylinder (5) is achieved by changing the positional relationship between the setting clamp (301) and the setting chamber (501). The setting clamp (301) is hung in the setting chamber (501) at the upper part of the connecting cylinder (5). When the throttling tool (0) that prevents liquid backflow in the gas well shaft is in a non-working state or an unset state, the setting clamp (301) is in a lifted state, with a gap between it and the bottom of the setting chamber (501), and the position in contact with the connecting cylinder (5) is tightly fitted. When the flow tool (0) is in working or setting state, the setting head (301) is pressed down and pushed into the setting chamber (501), fitting against the bottom of the setting chamber (501) and being locked; the groove provided on the upper part of the outer wall of the connecting cylinder (5) sequentially connects the upper cylindrical structure of the sleeve (7) and the setting spring (6), the groove provided on the middle part of the outer wall of the connecting cylinder (5) is used to set the petal structure below the sleeve (7), and the groove provided on the lower part of the outer wall of the connecting cylinder (5) is used to install the sealing ring (8).

[0010] Preferably, the symmetrical "expansion-contraction" configuration of the throttling channel (201) can be superimposed in series, and the number of the anti-liquid backflow spiral flow channel (202) is one or more; the anti-liquid backflow throttling fluid (2) can divide the upstream fluid into two parts, most of the fluid flows through the throttling channel (201) for throttling, acceleration and pressure reduction, and a small amount of fluid flows through the anti-liquid backflow spiral flow channel (202), so that the liquid cannot fall back into the wellbore; the core through hole of the throttling tool (0) in the gas wellbore that can prevent liquid backflow completely penetrates the entire structure, so that the upstream fluid can flow smoothly into the anti-liquid backflow throttling fluid (2), and after flowing through the throttling channel (201) and the anti-liquid backflow spiral flow channel (202) of the anti-liquid backflow throttling fluid (2), it maintains two flow modes and continues to advance in the wellbore.

[0011] Preferably, the device of the present invention closely combines the characteristics of gas-liquid fluid in the gas wellbore with the flow channel features formed by the fluid movement within the device. This ensures that the gas-liquid fluid smoothly enters the tool through the central through-hole that runs through the entire structure. In the throttling channel with a symmetrical "expansion-contraction" configuration that can be connected in series, most of the gas-liquid fluid undergoes throttling, acceleration, and pressure reduction. This allows most of the liquid to be carried downstream of the tool and accelerate forward at a certain distance. The remaining gas-liquid fluid that does not pass through the throttling channel can only advance spirally through the asymmetrical "contraction-expansion" flow channel structure to prevent liquid backflow. Thanks to the asymmetrical "contraction-expansion" flow channel structure, the forward resistance of the liquid is less than the backward resistance, thus ensuring that the liquid is less likely to fall back or flow back. Attached Figure Description

[0012] Figure 1 is a three-dimensional structural schematic diagram and a half-sectional view of the present invention.

[0013] Figure 2 is a schematic diagram showing the connection relationship between the anti-liquid backflow throttling fluid and other structures of the present invention.

[0014] Figure 3 is a schematic diagram of the connection relationship between the sleeve and the connecting cylinder in the non-setting and setting states of the present invention.

[0015] In the diagram, 0-a throttling tool inside the gas wellbore to prevent liquid backflow, 1-retrieval head, 2-anti-liquid backflow throttling device, 201-throttling channel, 202-anti-liquid backflow spiral channel, 3-sleeve, 301-setting clamp, 4-inlet cylinder, 5-connecting cylinder, 501-setting chamber, 6-setting spring, 7-clamp, 8-sealing ring. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] As shown in Figures 1 and 2, this embodiment of the invention provides a throttling tool for preventing liquid backflow in a gas wellbore. It may include: a retrieval head 1, a liquid backflow prevention throttling device 2, a sleeve 3, an inlet cylinder 4, a connecting cylinder 5, a setting spring 6, a clamping sleeve 7, a sealing ring 8, a throttling channel 201, a liquid backflow prevention spiral flow channel 202, a setting clamp 301, and a setting chamber 501. The retrieval head 1 has a central core hole that is through-hole. The liquid backflow prevention throttling device 2 has a cylindrical structure and includes key components such as the throttling channel 201 and the liquid backflow prevention spiral flow channel 202. The throttling channel 201 has a symmetrical "expansion-contraction" configuration and can be stacked in series. The through-hole formed by the "expansion-contraction" configuration of the throttling channel (201) is spherical or cup-shaped at the "expansion" configuration to prevent liquid backflow. The liquid backflow prevention spiral flow channel 202 has an asymmetrical "expansion-contraction" configuration. The flow channel structure of "contraction-expansion" is one or more, and is spirally distributed on the outer cylindrical surface of the anti-liquid backflow throttling fluid 2. The resistance of the fluid moving forward along the asymmetric "contraction-expansion" flow channel is less than the resistance moving backward, which can prevent the liquid from falling back. The sleeve 3 is a cylindrical structure. The lower part of the inner wall of the sleeve 3 is provided with a setting seal head 301. The connecting cylinder 5 is a cylindrical shape with a through hole of the same diameter as the inner wall of the sleeve 3. The outer wall has bosses and grooves of different diameters. The groove is provided at the upper part of the outer wall of the connecting cylinder 5. The groove has a concave cavity setting chamber 501 inside. The upper part of the ferrule 7 is cylindrical and the lower part is petal-shaped. The through hole formed by the connection of the retrieval head 1, the anti-liquid backflow throttling fluid 2, the inlet cylinder 4, and the connecting cylinder 5 constitutes the central through hole of the throttling tool 0 in the gas well shaft, which can completely penetrate the entire structure.

[0018] The retrieval head 1 and the anti-liquid backflow throttling fluid 2 are integral components. The upper end face of the throttling channel 201 is connected to the lower end face of the central hole of the retrieval head 1 and is coaxial, serving as the main flow channel for the fluid. The lower end face of the anti-liquid backflow throttling fluid 2 is provided with an internal thread, which is located between the throttling channel 201 and the anti-liquid backflow spiral flow channel 202. The upper end of the liquid inlet cylinder 4 is provided with an external thread. The lower end internal thread of the anti-liquid backflow throttling fluid 2 is screwed into the upper end external thread of the liquid inlet cylinder 4, ensuring that the anti-liquid backflow throttling fluid 2 is connected to the liquid inlet cylinder 4 while forming a through hole. The outer wall of the sleeve 3 is completely fitted with the inner wall of the gas well shaft. The upper part of the inner wall of the sleeve 3 is fitted with the outer wall of the anti-liquid backflow throttling fluid 2, ensuring that the fluid to be flowed can advance along the flow channel of the anti-liquid backflow spiral flow channel 202. There is a certain gap between the middle part of the inner wall of the sleeve 3 and the outer wall of the inlet cylinder 4, so that part of the fluid advances along the through hole of the inlet cylinder 4 and the anti-liquid backflow throttling fluid 2, and the other part enters the gap between the middle part of the inner wall of the sleeve 3 and the outer wall of the inlet cylinder 4 through the side wall hole of the inlet cylinder 4, and enters the anti-liquid backflow spiral flow channel 202 along the gap.

[0019] The connection between the sleeve 3 and the connecting sleeve 5 is achieved by changing the positional relationship between the setting clamp 301 and the setting chamber 501. The setting clamp 301 is hung in the setting chamber 501 at the upper part of the connecting sleeve 5. When the throttling tool 0, which prevents liquid backflow in the gas well shaft, is in a non-working or unset state, the setting clamp 301 is in a lifted state, with a gap between it and the bottom of the setting chamber 501, and the contact position with the connecting sleeve 5 is tightly fitted. When the throttling tool 0, which prevents liquid backflow in the gas well shaft, is in a working or set state, the setting clamp 301 is pressed down and pushed into the setting chamber 501, fitting against the bottom of the setting chamber 501 and being locked.

[0020] The groove on the upper part of the outer wall of the connecting cylinder 5 is connected in sequence to the upper cylindrical structure of the ferrule 7 and the setting spring 6. The groove in the middle part of the outer wall of the connecting cylinder 5 is used to set the petal-shaped structure below the ferrule 7. The groove on the lower part of the outer wall of the connecting cylinder 5 is used to install the sealing ring 8.

[0021] To better explain the working principle of the device, referring to Figures 1-3, the difference between the tool in a non-working state and a working state (unset state or set state) is that in the non-working state (unset state), the connection between the sleeve 3 and the connecting cylinder 5 is as shown in Figure 3(a). The setting clamp 301 is hung in the setting chamber 501 and is in a lifted state. There is a gap between it and the bottom of the setting chamber 501, and the position of contact with the connecting cylinder 5 is tightly fitted. In addition, the setting spring 6 is in a natural state without compression, and the petal-shaped structure below the clamp 7 is in a natural contraction state, which facilitates the tool to be lowered into the gas well shaft. In the working state (setting state), the setting clamp 301 is pressed down and pushed into the setting chamber 501, fitting against the bottom of the setting chamber 501 and being locked. At the same time, the setting spring 6 is compressed by the descending sleeve 3. The spring continues to transmit the compression force to the cylindrical structure on the upper part of the clamp 7 and pushes the clamp 7 downward. As the clamp 7 descends, the petal-shaped structure contacts the boss of the connecting cylinder 5 and expands, finally locking into the groove below the boss of the connecting cylinder 5, thus achieving locking. At this time, the clamp 7 fits tightly against the inside of the wellbore and firmly locks against the inner wall of the wellbore to achieve setting.

[0022] The working process of the device after setting is as follows: The gas-liquid fluid from the upstream direction first enters the tool through the central through hole at the bottom of the connecting cylinder 5. Since the sealing ring 8 seals the inner wall of the well barrel with the connecting cylinder 5, it ensures that the gas-liquid fluid can only enter through the central through hole at the bottom of the connecting cylinder 5. After advancing along the central through hole of the connecting cylinder 5 to the inlet cylinder 4, the gas-liquid fluid begins to split into two parts. Most of the fluid flows directly upward from the through hole of the inlet cylinder 4 into the throttling channel 201 of the anti-liquid backflow throttling fluid 2. Since the throttling channel 201 is in a symmetrical "expansion-contraction" form and can be superimposed in series, the through hole formed by the "expansion-contraction" configuration of the throttling channel (201) is in the shape of a spherical cone or a bowl at the "expansion" configuration, which can prevent the liquid from falling back. The "expansion-contraction" configuration can also accelerate the upward movement of the gas-liquid fluid. At the same time, pressure is reduced in this process. Finally, the fluid flows along the current flow state from the central through hole opened by the retrieval head 1. One part of the fluid flows out through the hole; while another part of the gas-liquid fluid enters the gap between the middle part of the inner wall of the sleeve 3 and the outer wall of the inlet cylinder 4 through the side wall hole of the inlet cylinder 4, and enters the anti-liquid backflow spiral channel 202 along the gap. Since the anti-liquid backflow spiral channel (202) has an asymmetrical "contraction-expansion" channel structure, it is spirally distributed along the outer cylindrical surface of the anti-liquid backflow throttling fluid (2) cylinder. The resistance of the fluid moving forward along the asymmetrical "contraction-expansion" channel is less than the resistance of moving backward, ensuring that this part of the fluid cannot fall back during the process of moving forward in the anti-liquid backflow spiral channel (202) and remains in the form of the channel to enter the downstream direction of the tool. The gas-liquid fluid after passing through the tool will produce two forms. The liquid will be carried by the accelerated airflow to flow downward for a longer distance. Through the device of the present invention, the tool can achieve throttling, speed increase, and pressure reduction while effectively preventing the liquid from falling back and improving the gas-liquid carrying capacity.

[0023] While the embodiments disclosed herein are as described above, the content is merely for the purpose of understanding this document and is not intended to limit it. Any person skilled in the art may make any modifications and changes to the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection herein shall still be determined by the scope defined in the appended claims.

Claims

1. A throttling device for preventing liquid backflow inside a gas well shaft, characterized in that, The system includes a retrieval head (1), a liquid backflow prevention throttling device (2), a sleeve (3), an inlet cylinder (4), a connecting cylinder (5), a setting spring (6), a ferrule (7), a sealing ring (8), a throttling channel (201), a liquid backflow prevention spiral flow channel (202), a setting clamp (301), and a setting chamber (501). The retrieval head (1) has a central hole that is through-hole. The liquid backflow prevention throttling device (2) has a cylindrical structure and includes key components such as the throttling channel (201) and the liquid backflow prevention spiral flow channel (202). The throttling channel (201) has a symmetrical "expansion-contraction" form. The through hole formed by the "expansion-contraction" configuration of the throttling channel (201) is spherical or cup-shaped at the "expansion" configuration, which can prevent liquid backflow. The anti-liquid backflow spiral channel (202) has an asymmetric "contraction-expansion" channel structure, which is spirally distributed along the outer cylindrical surface of the anti-liquid backflow throttling fluid (2) cylinder, and the resistance of the fluid moving forward along the asymmetric "contraction-expansion" channel is less than the resistance of moving backward; the sleeve (3) is a cylindrical structure, and a setting seal head (301) is provided at the lower part of the inner wall of the sleeve (3). The connecting cylinder (5) is a cylindrical shape, with a through hole of the same diameter as the inner wall of the sleeve (3) inside, and a boss and groove of different diameters on the outer wall. The groove is provided at the upper part of the outer wall of the connecting cylinder (5), and a cavity-type setting chamber (501) is provided inside the groove. The upper part of the ferrule (7) is cylindrical, and the lower part is petal-shaped; the retrieval head (1) and the anti-liquid backflow The through hole formed by connecting the throttling fluid (2), the inlet cylinder (4), and the connecting cylinder (5) constitutes the central through hole of the throttling tool (0) in the gas well shaft that can prevent liquid backflow, and can completely penetrate the entire structure; the retrieval head (1) and the anti-liquid backflow throttling fluid (2) are an integral component, the upper end face of the throttling channel (201) is connected to the lower end face of the central hole of the retrieval head (1) and is coaxial, which is the main flow channel of the fluid. The lower end face of the anti-liquid backflow throttling fluid (2) is provided with an internal thread, which is located between the throttling channel (201) and the anti-liquid backflow spiral flow channel (202). The upper end of the inlet cylinder (4) is provided with an external thread, and the lower end internal thread of the anti-liquid backflow throttling fluid (2) is screwed into the upper end external thread of the inlet cylinder (4) to ensure that the anti-liquid backflow throttling fluid is contained within the gas well shaft. While the backflow throttling fluid (2) is connected to the inlet cylinder (4), a through hole is formed; the outer wall of the sleeve (3) is completely fitted with the inner wall of the gas well shaft, and the upper part of the inner wall of the sleeve (3) is fitted with the outer wall of the anti-backflow throttling fluid (2), ensuring that the fluid to be flowed can advance along the flow groove of the anti-backflow spiral flow channel (202). There is a certain gap between the middle part of the inner wall of the sleeve (3) and the outer wall of the inlet cylinder (4), so that a part of the fluid advances along the through hole between the inlet cylinder (4) and the anti-backflow throttling fluid (2), and another part enters the gap between the middle part of the inner wall of the sleeve (3) and the outer wall of the inlet cylinder (4) through the side wall hole of the inlet cylinder (4), and enters the anti-backflow spiral flow channel (202) along the gap.The connection between the sleeve (3) and the connecting sleeve (5) is achieved by changing the positional relationship between the setting clamp (301) and the setting chamber (501). The setting clamp (301) is hung in the setting chamber (501) at the upper part of the connecting sleeve (5). When the throttling tool (0) that prevents liquid backflow in the gas well shaft is in a non-working state or an unset state, the setting clamp (301) is in a lifted state, with a gap between it and the bottom of the setting chamber (501), and the contact position with the connecting sleeve (5) is tightly fitted. When the device (0) is in the working state or the setting state, the setting head (301) is pressed down and pushed into the setting chamber (501), fitting against the bottom of the setting chamber (501) and being locked; the groove provided on the upper part of the outer wall of the connecting cylinder (5) sequentially connects the upper cylindrical structure of the sleeve (7) and the setting spring (6); the groove provided on the middle part of the outer wall of the connecting cylinder (5) is used to set the petal-shaped structure below the sleeve (7); the groove provided on the lower part of the outer wall of the connecting cylinder (5) is used to install the sealing ring (8).

2. The throttling tool for preventing liquid backflow inside the gas wellbore according to claim 1, characterized in that, The throttling channel (201) has a symmetrical "expansion-contraction" configuration and can be connected in series and superimposed. The number of anti-liquid fall spiral channels (202) is one or more.

3. The throttling tool for preventing liquid backflow inside the gas wellbore according to claim 1, characterized in that, The anti-liquid backflow throttling fluid (2) can divide the upstream fluid into two parts. Most of the fluid flows through the throttling channel (201) for throttling, acceleration and pressure reduction, while a small amount of fluid flows through the anti-liquid backflow spiral channel (202), so that the liquid cannot fall back into the wellbore.

4. The throttling tool for preventing liquid backflow inside the gas wellbore according to claim 1, characterized in that, The central through-hole of the throttling tool (0) that prevents liquid backflow in the gas wellbore completely penetrates the entire structure, allowing the upstream fluid to flow smoothly into the anti-liquid backflow throttling fluid (2), and after flowing through the throttling channel (201) and the anti-liquid backflow spiral channel (202) of the anti-liquid backflow throttling fluid (2), it maintains two flow patterns and continues to advance in the wellbore.

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