Insertion-type self-propelled mixed-flow drainage gas extraction tool and its drainage gas extraction method

Abstract

This invention relates to a tool for gas well drainage and gas production. This insert-type self-lifting mixed-flow drainage and gas production tool includes a cavity with a chamber. One end of the cavity is connected to a discharge pipe, which is connected to the discharge pipe via a diffuser. The inlet end of the diffuser is a narrow-diameter inlet located within the cavity, and the outlet end is an wide-diameter outlet connected to the discharge pipe. A throat with the smallest diameter is provided between the narrow-diameter inlet and the wide-diameter outlet. The other end of the cavity is connected to a gas pipe. A nozzle with a diameter smaller than the gas pipe is installed at the outlet of the gas pipe, communicating with the gas pipe. The nozzle is located within the cavity and points towards the inlet of the diffuser. A flow channel connecting the cavity to the outside is provided on the cavity wall. The key to this drainage and gas production method lies in controlling the gas-liquid mixing ratio in the discharge pipe. This drainage tool can be widely adapted to gas wells with different parameters, can be deployed in gas wells for extended periods, and can automatically discharge the liquid generated in the gas well. When necessary, it should be combined with appropriate tubing pressurization technology.

Description

Technical Field

[0001] This invention relates to gas well drainage and gas production, and more particularly to a tool for gas well drainage and gas production. Background Technology

[0002] Water generated inside gas wells can be drained through various methods, including self-flowing drainage, plunger lift, foam drainage, and combined drainage and gas production. However, the available drainage methods are limited for gas wells with different parameters. Therefore, it is necessary to design a drainage and gas production tool that can be widely adapted to gas wells with different parameters, has good drainage performance, and requires minimal maintenance, thus providing a new drainage option for the gas well drainage and gas production field. The self-lifting drainage and gas production device with announcement number CN201671603U is a device that uses downhole diameter throttling to change the natural gas flow rate and create a pressure difference before and after throttling. However, this device is not effective for dead wells where the pressure difference is insufficient. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an insertable self-lifting mixed flow drainage gas production tool. This drainage tool can be widely adapted to gas wells with different parameters. The drainage gas production tool can be deployed in the gas well for a long time and can automatically discharge the liquid generated in the gas well. When necessary, it should be combined with the corresponding drainage process.

[0004] The technical solution adopted by the present invention to solve its technical problem is: an insertable self-lifting mixed-flow drainage gas sampling tool, comprising a cavity having a chamber, one end of the cavity being connected to a discharge pipe, the cavity being connected to the discharge pipe through a diffuser, the inlet end of the diffuser being a narrow-diameter inlet located inside the cavity, the outlet end of the diffuser being an wide-diameter outlet connected to the discharge pipe, a throat with the smallest diameter being provided between the narrow-diameter inlet and the wide-diameter outlet, the other end of the cavity being connected to a trachea, and a nozzle with a diameter smaller than that of the trachea being installed at the outlet of the trachea, the nozzle being located inside the cavity and pointing towards the inlet of the diffuser.

[0005] Unless otherwise specified in this specification, "diameter" refers to the "inner diameter" of the corresponding tubular structure.

[0006] When gas at a certain pressure is introduced into the gas pipe, the gas velocity increases and the pressure decreases after passing through the narrow channel of the nozzle. The cavity is equipped with flow channels, through which liquid enters the cavity. The high-speed gas passing through the nozzle carries the liquid in the cavity through the diffuser. The diffuser has a small diameter at the throat and large diameters at both ends. After the high-speed gas carries the liquid through the throat of the diffuser, they are mixed and atomized. The resulting mist-like gas-liquid mixture flows towards the discharge pipe, thereby achieving drainage of the gas well.

[0007] The cavity is provided with pipe connectors at both ends. One pipe connector is used to connect the diffuser and the discharge pipe, and the other pipe connector is used to connect the air pipe and the nozzle to facilitate the assembly and adjustment of the tool. The specifications of the pipe connectors at the two locations can be different.

[0008] The diffuser tube and the cavity are connected by a threaded structure to achieve a basic sealed connection. At the same time, the distance between the inlet of the diffuser tube and the outlet of the nozzle can be easily adjusted to adjust the atomization effect of the gas-liquid mixture.

[0009] To facilitate the mixing ratio of the gas-liquid mixture in the discharge pipe based on the pressure difference between the trachea and the discharge pipe, in addition to changing the size of the trachea and nozzle, a more convenient method is to adjust the real-time flow rate of the liquid entering the chamber. Therefore, it is advisable to install a flow regulating valve on the flow channel.

[0010] Under normal conditions, the application scenario of the insertion-type self-lifting mixed-flow drainage gas extraction tool of the present invention is an oil pipe with accumulated liquid. When applying it, the cavity should be placed inside the oil pipe with accumulated liquid, and the insertion depth should be adjusted so that the inlet of the flow channel is below the liquid surface of the oil pipe, while the inlet of the gas pipe is above the liquid surface of the oil pipe. The accumulated liquid outside the cavity enters the cavity through the flow channel after passing through the flow regulating valve, and is drained by mixing and atomizing the accumulated liquid with the airflow ejected by the gas pipe nozzle. The drainage energy comes from the pressure energy inside the oil pipe.

[0011] The tool also includes a first pressure sensor for measuring the pressure inside the chamber, a second pressure sensor for measuring the pressure outside the chamber, and a gas supply network at the outlet end of the discharge pipe. The power supply and control module calculates and makes logical judgments based on the pressure measured by each pressure sensor and presets the pressure value at the outlet end of the discharge pipe to be slightly higher than the pressure of the gas supply network. According to the calculation method described in detail later in this specification, it outputs a signal to adjust the opening degree of the flow regulating valve. That is, the power supply and control module collects pressure sensor data and performs calculations to control the opening degree of the flow regulating valve, thereby controlling the flow rate of liquid entering the chamber and making the gas-liquid mixture form a suitable mixing ratio.

[0012] In essence, this invention achieves a balance between drainage efficiency and prevention of drainage failures by adjusting the appropriate liquid carrying capacity through pressure differential measurement. Based on the above description, it is also possible to design two or more flow channels, arranged in layers along the cavity axis. By adjusting the depth of the tool immersed below the liquid surface, the number of flow channels for liquid to flow into the cavity can be adjusted, thereby regulating the liquid carrying capacity.

[0013] In addition, by pressurizing the oil pipe, the kinetic energy of the gas-liquid fluid through the insertion-type self-lifting mixed-flow drainage gas extraction tool can be increased, thereby improving the drainage capacity of the insertion-type self-lifting mixed-flow drainage gas extraction tool. In this case, the inlet end of the gas pipe is connected to the pressurized gas source through the oil pipe.

[0014] The pressure source for the booster gas source can be the casing of the oil tubing, because the pressure inside the casing is usually greater than the pressure inside the oil tubing. The pressure source for the booster gas source can also be other gas spaces or external gas generating equipment. Other gas spaces can be nearby gas wells with higher gas pressure, etc.

[0015] The drainage gas extraction method of this invention controls the pressure difference between the gas pipe and the discharge pipe, or controls the flow rate of liquid entering the chamber, so that the mixing ratio of the gas-liquid mixture in the discharge pipe is within a set range. The aforementioned insertion-type self-lifting mixed-flow drainage gas extraction tool with a flow control valve can be used to control the opening of the flow regulating valve to control the flow rate of liquid entering the chamber, or an oil pipe pressurization process can be used to adjust the pressure difference between the gas pipe and the discharge pipe. One or both of these methods can be used simultaneously to ensure that the mixing ratio of the gas-liquid mixture in the discharge pipe is within a set range; specifically, the mixing ratio is not greater than the maximum mixing ratio M described below. MAX .

[0016] The beneficial effects of this invention are: when the gas well pressure is sufficient, drainage can be achieved using the gas well's own energy; if necessary, drainage can be achieved by combining it with tubing pressurization technology. Therefore, it is applicable to drainage of all gas wells, including those that have been flooded. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the insertion-type self-lifting mixed-flow drainage gas extraction tool of the present invention (using a casing for pressurization).

[0018] Figure 2 This is another schematic diagram of the overall structure of the insertion-type self-lifting mixed-flow drainage gas extraction tool of the present invention (using a pressurized gas source for pressurization).

[0019] Figure 3 yes Figure 1 Cross-sectional view of the mixed-flow drainage gas extraction tool.

[0020] Figure 4 yes Figure 3 Cross-sectional view of the diffuser tube.

[0021] Figure 5 yes Figure 3 Cross-sectional view of the central cavity.

[0022] Figure 6 yes Figure 3 Cross-sectional view of the nozzle.

[0023] Figure 7 This is another schematic diagram of the overall structure (multi-layer flow channel) of the insertion-type self-lifting mixed-flow drainage gas extraction tool of the present invention.

[0024] Figure 8 This is a schematic diagram illustrating the application of the mixed-flow drainage gas extraction tool of the present invention.

[0025] The diagram is labeled as follows: 1-Boosting pipeline, 2-Gas-liquid mixture, 3-Gas, 4-Casing, 5-Oil pipe, 6-Airflow, 7-Insertion-type self-lifting mixed-flow drainage gas sampling tool, 8-Accumulated liquid, 9-Regulating valve, 71-Discharge pipe, 72-Pipe connector, 73-Diffuser, 74-Cavity, 75-Nozzle, 76-Gas pipe, 701-Power supply and control module, 702-Flow regulating valve, 703-First pressure sensor, 704-Second pressure sensor, 731-Throat, 741-Cavity, 742-Flow channel, 743-Pressure measurement channel, 1001-Gas sampling tree, 1002-Gas pipe seal, 1003-Continuous gas pipe coil, P1-Cavity ambient pressure, P2-Cavity pressure, P3-Gas pipe inlet pressure, P4-Discharge pipe set pressure. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Example 1:

[0028] like Figures 1-6 As shown, the insertion-type self-lifting mixed-flow drainage gas extraction tool of the present invention is mainly used for gas well drainage. The tool is composed of multiple parts such as a discharge pipe 71, a diffuser pipe 73, a cavity 74, a pipe joint 72, a nozzle 75, and a gas pipe 76. The main body of the tool is a cavity 74 with a chamber 741. A flow channel 742 connecting the cavity 741 to the outside is provided on the cavity wall. One end of the cavity 74 is connected to the discharge pipe 71 through the diffuser pipe 73. The inlet end of the diffuser pipe 73 is a narrow-diameter inlet located in the cavity 741, and the outlet end of the diffuser pipe 73 is an expanding-diameter outlet connected to the discharge pipe 71. A throat 731 with the smallest diameter is provided between the narrow-diameter inlet and the expanding-diameter outlet. The other end of the cavity 74 is connected to the gas pipe. The trachea 76 is connected to the outlet of the trachea 76, which is connected to the trachea 76 and has a smaller diameter nozzle 75. The nozzle 75 is located in the chamber 741 and points towards the inlet of the diffuser 73. The power supply and control module 701 is fixedly installed at the step connecting the chamber 74 and the diffuser 73. The chamber wall of the chamber 741 is provided with a flow channel 742 connecting the chamber 741 and the outside. The flow regulating valve 702 is installed at the inlet of the flow channel 742 of the chamber. The first pressure sensor 703 is fixed on the outer wall of the chamber, which blocks the pressure measuring channel 743 of the chamber 741. The second pressure sensor 704 is adjacent to the first pressure sensor 703 and fixed on the outer wall of the chamber, and is used to measure the pressure outside the chamber.

[0029] The present invention utilizes the pressure difference between the trachea 76 and the discharge pipe 71 to allow the liquid entering the chamber 741 through the flow channel 742 to converge with the airflow from the nozzle 75. The two fluids mix at the throat 731 of the diffuser, allowing the liquid to be discharged through the discharge pipe 71 along with the gas ejected from the nozzle 75, thus achieving drainage.

[0030] Due to the long distance and high height of the discharge pipe, when the fluid passes through the discharge pipe, the fluid will be subject to fluid resistance and combined with the influence of fluid gravity to resist the pressure energy inside the oil pipe. The fluid resistance is also affected by factors such as fluid viscosity, pipe wall roughness, and flow velocity. Fluid gravity is mainly affected by fluid density. In order to achieve a good drainage effect, it is necessary to avoid the formation of long liquid columns or excessive high-density gas-liquid mixtures in the discharge pipe.

[0031] In this invention, a first pressure sensor measures the pressure P1 in the chamber, and a second sensor measures the pressure P2 in the surrounding environment outside the chamber. When the airflow passes through the nozzle, the gas velocity increases and the pressure decreases, resulting in a decrease in the chamber pressure, where P2 > P1. Considering the discharge pipe as a small-diameter oil pipe, the gas velocity in the pipe needs to reach a critical liquid-carrying velocity to prevent droplets from falling and forming liquid accumulation. A critical liquid-carrying velocity V is obtained through a formula or experimental method. 临 Let the gas velocity in the outlet pipe after the nozzle be V1. The pressure inside the cavity is affected by the gas velocity, and a functional relationship can be established: V1 = f(P1). The specific functional relationship is obtained through computer fluid simulation analysis or experiments, and it is necessary to ensure that V1 ≥ V 临 That is, f(P1)≥V 临 (Equation 1) Let the gas flow rate in the discharge pipe after the nozzle outlet be Q1, and the cross-sectional area of ​​the discharge pipe channel be S. Then Q1 = SV1, i.e., Q1 = S·f(P1). (Pipe flow rate calculation formula) ΔP is the pressure difference, ρ is the fluid density, g is the acceleration due to gravity, s is the flow resistance, and l is the pipe length. The formula is simplified to... By using a simplified formula for calculating pipe flow rate, the relationship between the flow rate (denoted as Q2) of the accumulated liquid through the flow control valve and flow channel and the pressure difference can be calculated. R is a coefficient obtained through computer fluid simulation analysis or experimental methods. Since the internal flow channel of the flow control valve is adjustable, the value of R is a variable parameter. The gas-liquid mixing ratio in the discharge pipe (where the gas-liquid mixing ratio is liquid flow rate / gas flow rate, denoted as M) is then... The maximum gas-liquid mixing ratio M was obtained through experimental methods. max Then M needs to be guaranteed max ≥M, that is (Equation 2) By combining Equations 1 and 2, a parametric relationship model is established. Using the pressure values ​​calculated by the power supply and electronic control module program, the opening of the flow regulating valve is controlled to obtain a suitable gas-liquid mixing ratio. This prevents the formation of liquid columns or excessive high-density gas-liquid mixtures in the discharge pipe, achieving continuous drainage operation while maintaining drainage efficiency. For example... Figures 1-3As shown, pipe connectors 72 are provided at both ends of the cavity 74. One pipe connector 72 is used to connect the diffuser 73 and the discharge pipe 71, and the other pipe connector 72 is used to connect the air pipe 76 and the nozzle 75. Figures 1-3 The diagram shows a case where one pipe joint is used at each end of the cavity. Multiple reducing pipe joints can be used when necessary to facilitate the replacement of gas pipes, discharge pipes or nozzles with different inner diameters according to different gas well parameters.

[0032] like Figure 3 As shown, the diffuser 73 and the cavity 74 are connected by a threaded structure, which allows for easy adjustment of the position of the diffuser 73's inlet within the cavity 74. This indirectly adjusts the distance between the nozzle 75 and the diffuser 73's inlet, thereby indirectly adjusting the drainage efficiency to a suitable level. Adjusting the position of the nozzle 75 relative to the diffuser aims to regulate the atomization effect. Larger droplets tend to adhere to the wall of the discharge pipe 71, thus weakening the drainage function of the airflow, while smaller droplets are more easily carried out by the airflow.

[0033] Theoretically, the smaller the diameter of the discharge pipe within a certain range, the greater the pressure difference between the gas pipe and the discharge pipe, the higher the flow velocity of the gas-liquid mixture, and the higher the drainage efficiency. Increasing the pressure difference usually relies on increasing the pressure inside the gas pipe, which can be achieved by connecting a pressurizing gas source to the gas pipe 76. The pressure source can be the casing 4 of the tubing 5, because the pressure inside the casing 4 is usually greater than the pressure inside the tubing 5. In addition to pressurizing the tubing through the casing of the gas well itself, pressurization methods for the tubing can include introducing gas from other gas wells, or using gas generation equipment. The methods for pressurizing the tubing are not limited to those described above.

[0034] Example 2:

[0035] like Figure 7 As shown, compared with Example 1, Example 2 differs in that it does not have a pressure sensor and a flow regulating valve. There are more than two flow channels 742, which are arranged in layers along the axis of the cavity. By adjusting the number of layers or quantities of flow channels below the liquid surface through the lifting tool body, the flow rate entering the cavity can be manually adjusted. Ultimately, the flow rate entering the cavity is matched with the pressure difference between the air pipe and the discharge pipe, ensuring smooth liquid discharge while ensuring the discharge efficiency with a suitable gas-liquid mixing ratio.

[0036] Example 3:

[0037] refer to Figures 1 to 6 ,like Figure 8As shown, the insertion-type self-lifting mixed-flow drainage gas production tool is used by inserting it into the gas well. A gas tree 1001 with a gas pipe seal 1002 is installed at the wellhead. After passing through the gas tree 1001, the main body of the tool enters the tubing 5. The discharge pipe 71 is wound and connected to the continuous tubing coil 1003. The continuous tubing coil 1003 allows the discharge pipe 71 to be extended and retracted. The gas pipe seal 1002 acts as a sealing component to prevent gas leakage from the top of the well. By rotating the continuous tubing coil 1003, the insertion-type self-lifting mixed-flow drainage gas production tool is slowly deployed from the wellhead into the depth of the tubing, thereby draining the accumulated fluid deep within the tubing.

[0038] For water-flooded wells, due to low formation energy, directly using an insert-type self-lifting mixed-flow drainage gas production tool may not achieve good drainage results. It's advisable to first maintain pressure in the dead well to increase tubing pressure, and then gradually insert the insert-type self-lifting mixed-flow drainage gas production tool into the tubing to drain the water and see if it can restore the well's flow. If the gas well cannot continuously drain the fluid accumulated inside the tubing, then a tubing pressurization process combined with the insert-type self-lifting mixed-flow drainage gas production tool is necessary for drainage. Figure 1 As shown, a booster gas source can be introduced into the oil pipe 5 through a booster pipe 1 equipped with a regulating valve 9, thereby increasing the oil pipe pressure.

[0039] like Figure 8 As shown, drainage is achieved using the tool of this invention in conjunction with the oil pipe pressurization process. The preferred method is as follows: Figure 1 The method shown involves using the gas in the casing of the gas well itself to pressurize the tubing. The pressure inside casing 4 is greater than the pressure inside tubing 5. Gas from casing 4 is introduced into tubing 5 through the pressurization pipeline. The flow rate of the introduced gas is controlled to control the increase of tubing pressure within a certain range. After the tubing pressure increases, the pressure at the gas pipe also increases. The pressure difference between the gas pipe inlet and outlet increases, increasing the pressure potential energy. This increases the airflow velocity and kinetic energy within the insertion-type self-lifting mixed-flow drainage gas production tool, and also increases its water-carrying capacity.

[0040] Besides pressurizing the tubing through the casing of the gas well itself, other methods for pressurizing the tubing include... Figure 2 As shown, the oil tubing can be pressurized by introducing gas from other gas wells, or by using gas production equipment. The methods for pressurizing the oil tubing are not limited to those described above.

[0041] It should also be noted that, due to convention, the pressure mentioned in this instruction manual, strictly speaking, refers to pressure intensity.

Claims

1. An insertion-type self-lifting mixed-flow drainage gas sampling tool, comprising a cavity (74) having a chamber (741), one end of which is connected to a discharge pipe (71), characterized in that: The cavity (74) is connected to the discharge pipe (71) via a diffuser (73). The inlet end of the diffuser (73) is a narrowed inlet located inside the cavity (741), and the outlet end of the diffuser (73) is an expanded outlet connected to the discharge pipe (71). A throat (731) with the smallest diameter is provided between the narrowed inlet and the expanded outlet. The other end of the cavity (74) is connected to the trachea (76). The outlet of the trachea (76) is equipped with a nozzle (75) with a diameter smaller than that of the trachea (76) that communicates with the trachea (76). The nozzle (75) is located inside the cavity (741) and points to the trachea. The inlet of the diffuser (73) is provided with a flow channel (742) on the wall of the chamber (741) connecting the chamber (741) to the outside. A flow regulating valve (702) is installed on the flow channel (742). The tool also includes a first pressure sensor (703) for measuring the pressure inside the chamber (741), a second pressure sensor (704) for measuring the pressure outside the chamber (741), and a power supply and control module (701). The power supply and control module (701) adjusts the opening of the flow regulating valve (702) according to the pressure measured by each pressure sensor.

2. The insertion-type self-propelled mixed-flow drainage gas extraction tool as described in claim 1, characterized in that: The cavity (74) is provided with pipe joints (72) at both ends. One pipe joint (72) is used to connect the diffuser (73) and the discharge pipe (71), and the other pipe joint (72) is used to connect the air pipe (76) and the nozzle (75).

3. The insertion-type self-lifting mixed-flow drainage gas extraction tool as described in claim 1, characterized in that: The diffuser tube (73) and the cavity (74) are connected by a threaded structure.

4. The insertion-type self-propelled mixed-flow drainage gas extraction tool as described in claim 1, characterized in that: The flow channel (742) has two or more channels, and is arranged in layers along the axis of the cavity.

5. The insertion-type self-propelled mixed-flow drainage gas extraction tool as described in any one of claims 1 to 4, characterized in that: The cavity (74) is located inside the oil pipe (5) with accumulated liquid (8), the inlet of the flow channel (742) is located below the liquid level of the oil pipe (5), and the inlet of the gas pipe (76) is located above the liquid level of the oil pipe (5).

6. The insertion-type self-propelled mixed-flow drainage gas extraction tool as described in claim 5, characterized in that: The inlet end of the gas pipe (76) is connected to the booster gas source through the oil pipe (5), and the pressure source of the booster gas source is the sleeve (4) of the oil pipe (5).

7. The insertion-type self-propelled mixed-flow drainage gas extraction tool as described in claim 5, characterized in that: The inlet end of the gas pipe (76) is connected to a pressurized gas source, the pressure source of which is other gas space or external gas generating equipment.

8. A drainage and gas extraction method using the insertion-type self-propelled mixed-flow drainage and gas extraction tool according to any one of claims 1 to 7, characterized in that: Control the pressure difference between the trachea (76) and the discharge tube (71) or control the flow rate of liquid entering the chamber (741) so that the mixing ratio of the gas-liquid mixture in the discharge tube (71) is within a set range.

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