Evaluation device and method suitable for foam drainage gas recovery in horizontal well section

Abstract

The application discloses an evaluation device and method suitable for foam liquid drainage gas production of horizontal well sections, and belongs to the technical field of natural gas exploitation. The evaluation device comprises an experimental tube which is internally detachably installed with a foam liquid drainage gas production pipe column or a contrast pipe column; a gas supply unit, a liquid supply unit and a foaming liquid supply unit are connected with the experimental tube through a gas-liquid mixer; gas, experimental liquid and foaming agent solution are mixed in the gas-liquid mixer and then enter the experimental tube, so that the gas-liquid two-phase flow and the downside liquid accumulation state in the horizontal well section are simulated; the experimental tube is connected with a liquid accumulation height metering unit and a gas-liquid separation metering unit; the gas-liquid separation metering unit is connected with a liquid drainage collection unit; a conveying unit, the gas-liquid mixer, the liquid accumulation height metering unit and an outlet end of the experimental tube are connected with a data acquisition unit; the evaluation method is to realize horizontal liquid accumulation simulation and liquid drainage foaming through the evaluation device, to arrange and comparatively analyze experimental data, and to quantitatively evaluate the liquid drainage foaming effect of the foam liquid drainage gas production pipe column.

Description

Technical Field

[0001] This invention belongs to the field of natural gas extraction technology, and specifically relates to an evaluation device and method suitable for foam drainage gas extraction in horizontal well sections. Background Technology

[0002] As gas reservoir development enters the middle and late stages, formation energy gradually decreases, reducing the fluid-carrying capacity of gas wells. Fluid accumulation in the wellbore gradually becomes a significant factor affecting stable gas well production. Fluid accumulation in the wellbore increases bottomhole back pressure, reduces production differential, and in severe cases, can cause reduced gas well production or even water flooding and shutdown. For water-bearing gas reservoirs and low-pressure gas reservoirs, the problem of fluid retention in horizontal well sections is even more pronounced.

[0003] Horizontal well sections exhibit distinct gravity differentiation characteristics compared to vertical well sections. The gas phase typically flows at high speed along the upper part or central region of the tubing string, while the liquid phase is more easily affected by gravity, flowing back, settling, and accumulating along the lower wall of the tubing string. When gas velocity is insufficient, foam stability decreases, or the liquid supply increases, continuous liquid films, localized liquid pools, or intermittent liquid plugs can form on the lower side of the horizontal well section, thereby increasing flow resistance and weakening the gas-liquid carrying capacity.

[0004] Foam drainage is a common method for managing liquid accumulation in gas wells. This method typically relies on a foaming agent to react with the accumulated liquid in the wellbore, forming foam under the disturbance of natural gas flow. This foam reduces the apparent density of the liquid system and increases the gas's liquid-carrying capacity, thus achieving drainage and gas production. However, during long-distance migration in horizontal well sections, the foam can rupture due to factors such as gravity differentiation, wall friction, shear attenuation, and liquid film drainage. The liquid phase released after foam rupture will then flow back and settle along the bottom of the tubing, forming secondary liquid accumulation.

[0005] Existing fluid drainage and gas production tools mostly focus on enhancing disturbance, increasing fluid carrying velocity, or improving local mixing. Some structures enhance gas-liquid contact through spiral guides, flow holes, or vortex components. While these structures can improve gas-liquid mixing to some extent, their technical focus is usually limited to local disturbance. They lack continuous structural coordination design for how to recapture the refluxed fluid after foam collapse in horizontal well sections, how to retain it for a short period, and how to re-entrain it into the mainstream to form stable foam.

[0006] On the other hand, if only the drainage tubing itself is designed locally, without supporting structures such as gas supply, liquid supply, quantitative injection of foaming fluid, gas-liquid mixing, simulation of liquid accumulation in horizontal sections, monitoring of liquid accumulation height, gas-liquid separation and metering, and data acquisition, it is difficult to fully demonstrate the drainage and foaming capacity of the tubing under different operating conditions, and it is also not conducive to comparing and evaluating the contribution of each structural unit. Therefore, it is necessary to establish a complete system outside the core drainage tubing, which can not only simulate the gas-liquid two-phase flow in horizontal well sections, but also continuously, quantitatively, and repeatably evaluate the drainage and foaming effect. Summary of the Invention

[0007] The purpose of this invention is to provide an evaluation device and method suitable for foam drainage gas production in horizontal well sections, so as to solve the problems that existing foam drainage gas production tools only focus on the local structure of a single tubing string, lack complete system support, are difficult to simulate the liquid accumulation state in horizontal well sections, and are difficult to quantitatively evaluate the drainage foaming effect.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] An evaluation device for foam drainage gas production in horizontal well sections is disclosed. The device includes a gas supply unit, a liquid supply unit, a foaming agent supply unit, and a horizontally arranged transparent experimental tube. A foam drainage gas production string or a control string can be detachably installed inside the experimental tube. The gas supply unit, liquid supply unit, and foaming agent supply unit respectively provide the gas, experimental liquid, and foaming agent solution required for the experiment. A gas-liquid mixer is provided at the inlet end of the experimental tube. The gas supply unit is connected to the gas-liquid mixer. The liquid supply unit and the foaming agent supply unit are connected to the gas-liquid mixer via a conveying unit. The conveying unit controls the injection volume, injection rate, and injection ratio of the experimental liquid and foaming agent solution. The gas-liquid mixer mixes the gas, experimental liquid, and foaming agent solution to form a gas-liquid mixture. This gas-liquid mixture enters the experimental tube to simulate the gas-liquid two-phase flow and the underlying liquid accumulation state in the horizontal well section.

[0010] The experimental tube is connected to a liquid accumulation height measuring unit, which measures the liquid accumulation height or liquid film thickness at the bottom of the experimental tube. The outlet end of the experimental tube is connected to a gas-liquid separation measuring unit, which separates and measures the gas-liquid mixture after it has passed through the foam drainage gas collection tube. The gas-liquid separation measuring unit is connected to a drainage collection unit, which collects the separated liquid.

[0011] The delivery unit, gas-liquid mixer, liquid accumulation height metering unit, and experimental tube outlet are all connected to the data acquisition unit to collect gas flow rate, liquid flow rate, foaming agent solution injection volume, tube pressure difference, liquid accumulation height, outlet discharge volume, image data, and experimental time data.

[0012] Furthermore, the gas supply unit is connected to the gas-liquid mixer via a pressure regulating valve and a gas flow control element; the delivery unit includes a metering pump and an injection pipeline, the outlets of the liquid supply unit and the foaming liquid supply unit are both connected to the inlet of the metering pump, and the outlet of the metering pump is connected to the gas-liquid mixer via multiple parallel injection pipelines.

[0013] The liquid accumulation height measuring unit is equipped with a transparent observation area, a liquid level scale, and a liquid level gauge. The liquid level gauge can be replaced by a laser liquid level monitor, all of which are used to measure the liquid accumulation height or liquid film thickness.

[0014] Furthermore, the experimental tube is a transparent cylindrical tube sealed at both ends. The two ends of the foam drainage and gas sampling tube are detachably installed inside the experimental tube through connectors, and its inlet and outlet ends are respectively sealed and connected to the inlet and outlet ends of the experimental tube.

[0015] The foam drainage and gas collection tubing includes a main body and a double-helix guide plate disposed inside it. The internal cavity of the main body forms a main channel. After the gas-liquid mixture enters through the inlet end of the experimental tube, it flows towards the outlet end along the main channel. The double-helix guide plate includes two guide plates, both of which are located in the main channel and are fixed to the inner wall of the main body of the drainage and gas collection tubing in a spiral spatially interlaced manner.

[0016] Furthermore, the double-helix guide plate adopts a segmented variable pitch structure along its length, which includes a dense pitch section, a transition pitch section, and a sparse pitch section from the inlet end to the outlet end.

[0017] Furthermore, the guide plate is provided with multiple notches, which are spaced apart along the length direction of the guide plate; the length direction of the notches forms an inclined angle with the length direction of the guide plate, and the notches penetrate through both sides of the guide plate.

[0018] Furthermore, the guide plate is provided with a composite step on the side near the inner wall of the main body of the drainage pipe column. The surface of the composite step is divided into a liquid-introducing surface, a liquid-stagnating groove, a check-back step surface, and a re-entrainment transition surface in sequence.

[0019] Furthermore, the inner wall of the main body of the drainage pipe string, the surface of the double helix guide plate, the surface of the notch, and the surface of the composite step are all provided with a modified nano-SiO2 epoxy double-hydrophobic coating.

[0020] Furthermore, the data acquisition unit includes a pressure acquisition module, a flow acquisition module, a liquid level acquisition module, an image acquisition module, a timing module, and a data processing module. The pressure acquisition module includes pressure gauges installed at the inlet and outlet of the experimental tube. The flow acquisition module includes a flow meter installed on the injection pipeline at the outlet of the metering pump. The liquid level acquisition module is a liquid level gauge on the liquid accumulation height measuring unit. The image acquisition module is installed on the side of the experimental tube. The timing module is used to record the start time of the experiment, the duration of the experiment, and the timestamps corresponding to each acquired data. The data processing module is installed in a computer. The pressure acquisition module, flow acquisition module, liquid level acquisition module, and image acquisition module are all connected to the computer.

[0021] This invention also provides an evaluation method for foam drainage gas production in horizontal well sections, comprising the following steps:

[0022] Step 1: Assemble the above-mentioned evaluation device and install the foam drainage and gas sampling tubing inside the horizontal experimental tube, so that the foam drainage and gas sampling tubing is arranged coaxially with the experimental tube.

[0023] Step 2: Start the data acquisition unit and initialize the acquisition parameters for gas flow rate, liquid flow rate, foaming agent solution injection volume, pressure, liquid accumulation height, and liquid discharge volume;

[0024] Step 3: The experimental liquid and the foaming agent solution are injected into the gas-liquid mixer through the liquid supply unit and the foaming liquid supply unit, respectively, and the experimental liquid is formed according to the set ratio. The mass concentration of the foaming agent in the experimental liquid is 0.01%-2.0%, preferably 0.05%-0.5%. At the same time, an initial liquid film or local liquid accumulation state is formed on the lower side of the experimental tube, and the initial liquid accumulation height is recorded by the liquid accumulation height measurement unit. The initial image and initial operating condition data are recorded by the data acquisition unit.

[0025] Step 4: Start the gas supply unit to allow the gas, experimental liquid, and foaming agent solution to form an initial gas-liquid mixture through the gas-liquid mixer and enter the experimental tube;

[0026] Step 5: The gas-liquid mixture flows through the foam drainage and gas collection column in the experimental tube to conduct a foam drainage and gas collection experiment.

[0027] Step 6: Record the changes in liquid height in the experimental tube during the experiment using the liquid height metering unit; separate and meter the outlet gas-liquid mixture using the gas-liquid separation metering unit; collect the separated liquid using the liquid collection unit; and record the gas flow rate, liquid flow rate, foaming agent solution injection volume, tube pressure difference, outlet liquid discharge volume, experimental images, and experimental time data using the data acquisition unit.

[0028] Step 7: The experimenters retrieved liquid accumulation height, flow rate, pressure, outlet discharge volume and image data under different times and operating conditions through the data acquisition unit, and generated liquid accumulation height change map, liquid phase distribution map, foam migration map, binary liquid film distribution map, analysis report and experimental log;

[0029] Step 8: Change the gas flow rate of the gas supply unit, the liquid flow rate of the liquid supply unit, the foaming agent solution concentration of the foaming liquid supply unit, or the initial liquid accumulation height in the experimental tube to re-form the initial liquid film or local liquid accumulation state under the corresponding working conditions, and repeat steps 3 to 7 to obtain the drainage foaming performance data under different working conditions.

[0030] Step 9: Replace the foam drainage and gas collection tubing in the experimental tube with the control tubing, reinitialize the data acquisition parameters, and repeat steps 3 to 7 under the same experimental conditions; if it is necessary to obtain control data under different operating conditions, repeat the experiment according to the parameter change method in step 8, and compare the experimental data of the foam drainage and gas collection tubing with the control tubing to evaluate the drainage and gas collection performance of the foam drainage and gas collection tubing.

[0031] Under the same experimental conditions, for foam drainage gas collection tubing with different sizes, inner diameters, or structural parameters, repeating the above steps will yield drainage foaming performance data for the corresponding structure.

[0032] Furthermore, based on the liquid height data collected by the liquid height metering unit, the liquid height reduction rate is calculated, and its expression is as follows:

[0033]

[0034] in, The height of the liquid in the experimental tube at the initial moment of the experiment. For the experiment to proceed to The height of the fluid at that moment. The rate of decrease in fluid height;

[0035] The liquid height reduction rate is used to characterize the ability of the foam drainage gas sampling string to reduce the liquid accumulation on the lower side of the experimental tube. The larger the value, the more significant the drainage and gas collection effect;

[0036] The experimental images acquired by the data acquisition unit are subjected to grayscale and binarization processing on the liquid film distribution inside the experimental tube, and the area ratio of the liquid film is calculated. The expression is as follows:

[0037]

[0038] in, Let A represent the area of ​​the liquid film-covered region in the binary liquid film distribution map, and let A be the total area of ​​the image observation region. This represents the percentage of the liquid film area.

[0039] The liquid film area ratio is used to characterize the degree of liquid retention in the experimental tube. The smaller the value, the smaller the area of ​​the remaining liquid film in the experimental tube, and the better the drainage effect of the foam drainage gas sampling column.

[0040] The discharge efficiency is calculated based on the outlet discharge volume obtained from the gas-liquid separation metering unit and the discharge collection unit. The expression for this efficiency is:

[0041]

[0042] in, To set the cumulative volume of discharged liquid collected by the discharge collection unit within the experimental time, This represents the initial total volume of liquid injected into the experiment. For drainage efficiency;

[0043] Drainage efficiency is used to characterize the overall drainage capacity of a foam drainage gas sampling string within a set experimental time. The larger the value, the stronger the liquid discharge capacity of the gas sampling tubing.

[0044] The technological advancements achieved by this invention compared to existing technologies are as follows:

[0045] This invention can simultaneously achieve gas supply, liquid supply, foaming liquid supply, gas-liquid mixing, horizontal liquid accumulation simulation, liquid drainage foaming, gas-liquid separation metering, and data acquisition, making the device structure more complete. The foam drainage gas production string can be detachably installed inside a horizontal transparent experimental tube, which can maintain the continuity of the flow simulation in the horizontal well section and facilitate the replacement of the control string for easy comparison and evaluation. By sorting, calculating, and comparing the experimental data, evaluation indicators such as liquid accumulation height reduction rate, liquid film area ratio, and drainage efficiency can be obtained, which can comprehensively evaluate the drainage and gas production performance of the foam drainage gas production string under different gas flow rate, liquid flow rate, foaming liquid concentration, and initial liquid accumulation height conditions. This invention has a simple structure, is easy to operate, and can quantitatively evaluate the drainage and foaming effect of the foam drainage gas production string. Attached Figure Description

[0046] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0047] In the attached diagram:

[0048] Figure 1 A schematic diagram of the structure of an evaluation device for foam drainage gas production in horizontal well sections provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the structure of the foam drainage gas collection tubing in an embodiment of the present invention;

[0050] Figure 3 This is a layout diagram of the internal double-helix guide plate of the main body of the drainage pipe column in the embodiment of the present invention under transparent view;

[0051] Figure 4 for Figure 2 A schematic diagram of the arrangement of the guide plate at point A on the inner wall of the main body of the drainage pipe string (partial cross-section along the axial direction of the main body of the drainage pipe string);

[0052] Figure 5 for Figure 2Axial sectional view of the guide plate at point B on the upper end face of the inner wall of the main body of the drainage pipe string;

[0053] Figure 6 for Figure 2 A partial sectional view of the main body of the drainage pipe string at point C;

[0054] Figure 7 This is a cross-sectional view of the main body of the drainage pipe column in an embodiment of the present invention, perpendicular to the axis.

[0055] Figure 8 This is a cross-sectional view of the main body of the drainage pipe string along its axial direction in an embodiment of the present invention;

[0056] Figure 9 This is a cross-sectional view of the junction between the guide plate and the inner wall of the main body of the drainage pipe in an embodiment of the present invention;

[0057] In the picture:

[0058] 1. Gas supply unit; 2. Liquid supply unit; 3. Foaming liquid supply unit; 4. Conveying unit; 41. Metering pump; 42. Injection pipeline; 5. Gas-liquid mixer; 6. Experimental tube; 7. Liquid accumulation height metering unit; 8. Gas-liquid separation metering unit; 9. Drainage collection unit; 10. Data acquisition unit; 11. Drainage and extraction tubing main body; 12. Double helix guide plate; 13. Notch; 14. Composite step; 15. Modified nano-SiO2 epoxy double hydrophobic coating; 16. Liquid-facing inlet surface; 17. Stagnation groove; 18. Check valve step surface; 19. Re-entrainment transition surface; 20. Guide plate. Detailed Implementation

[0059] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0060] like Figure 1As shown in the figure, an evaluation device for foam drainage gas production in horizontal well sections is provided by an embodiment of the present invention. The evaluation device includes a gas supply unit 1, a liquid supply unit 2, a foaming liquid supply unit 3, and a horizontally arranged transparent experimental tube 6. A foam drainage gas production tubing or a control tubing (not shown in the figure) can be detachably installed in the experimental tube 6. The gas supply unit 1, the liquid supply unit 2, and the foaming liquid supply unit 3 are used to provide the gas, experimental liquid, and foaming agent solution required for the experiment, respectively. A gas-liquid mixer 5 is provided at the inlet end of the experimental tube 6. The gas supply unit 1 is connected to the gas-liquid mixer 5. The liquid supply unit 2 and the foaming liquid supply unit 3 are connected to the gas-liquid mixer 5 through a conveying unit 4. The conveying unit 4 is used to control the injection volume, injection speed, and injection ratio of the experimental liquid and the foaming agent solution. The gas-liquid mixer 5 is used to mix the gas, experimental liquid, and foaming agent solution to form a gas-liquid mixture. The gas-liquid mixture enters the experimental tube 6 to simulate the gas-liquid two-phase flow and the liquid accumulation state on the lower side in the horizontal well section. In specific installation, the gas supply unit 1, liquid supply unit 2, and foaming liquid supply unit 3 are arranged side by side on the test bench. The experimental tube 6 is mounted above the test bench via a support frame. Different types of foam drainage gas sampling tubing or control tubing are replaced within the same horizontal transparent experimental tube to evaluate the drainage foaming performance under different structural parameters. The gas supply unit 1 is a gas cylinder that provides gas with adjustable pressure and flow rate; the liquid supply unit 2 is a storage tank that contains the experimental liquid or simulated formation water; the foaming liquid supply unit 3 is a storage tank that contains the foaming agent solution. In specific implementation, the gas in the gas supply unit 1 is nitrogen, compressed air, or simulated natural gas, preferably nitrogen; the experimental liquid in the liquid supply unit 2 is clean water, brine, or simulated formation water, preferably simulated formation water. The foaming agent solution is prepared using existing foam drainage gas sampling foaming agents, and the foaming agent can be one or more compound systems of anionic, nonionic, and amphoteric surfactants. The mass concentration of the foaming agent in the experimental solution ranges from 0.01% to 2.0%, preferably from 0.05% to 0.5%.

[0061] The liquid accumulation height measuring unit 7 is located on the side or bottom of the experimental tube 6 and corresponds to the liquid accumulation observation area below the main channel of the foam drainage gas sampling column. It is used to measure the liquid accumulation height or liquid film thickness below the main channel. The outlet end of the foam drainage gas sampling column is sealed and connected to the outlet end of the experimental tube 6 through a connector. The outlet end of the experimental tube 6 is connected to the inlet end of the gas-liquid separation measuring unit 8 through a pipeline. The gas-liquid separation measuring unit 8 can be an existing gas-liquid separator, such as a vertical gravity gas-liquid separator or a transparent gas-liquid separation measuring cylinder. Its pressure resistance rating and processing flow rate are matched with the experimental conditions. It is used to separate and measure the gas-liquid mixture after it has been processed by the foam drainage gas sampling column. The gas-liquid separation measuring unit 8 is connected to the drainage collection unit 9, which is used to collect the separated liquid.

[0062] The liquid accumulation height measuring unit 7 is equipped with a transparent observation area, a liquid level scale, and a liquid level gauge. The liquid level gauge can be replaced by a laser liquid level monitor. Both are used to measure the liquid accumulation height or liquid film thickness, enabling manual reading or non-contact measurement. The gas-liquid separation measuring unit 8 includes a gas-liquid separator, a liquid level gauge, and a flow meter. The inlet end of the gas-liquid separator is connected to the outlet end of the experimental tube. The gas outlet is located at the upper part of the gas-liquid separator, and the liquid outlet is located at the lower part. The liquid level gauge and the outlet flow meter are used to measure the volume or flow rate of the liquid discharged per unit time. After gas-liquid separation, the liquid outlet of the gas-liquid separator is connected to the drainage collection unit to collect the separated liquid.

[0063] The delivery unit 4, gas-liquid mixer 5, liquid accumulation height metering unit 7, and the outlet end of the experimental tube 6 are all connected to the data acquisition unit 10 for collecting gas flow rate, liquid flow rate, foaming agent solution injection volume, tube pressure difference, liquid accumulation height, outlet discharge volume, image data, and experimental time data.

[0064] In specific manufacturing, the gas supply unit 1 is connected to the gas-liquid mixer 5 through a pressure regulating valve and a gas flow control element; the delivery unit 4 includes a metering pump 41 and an injection pipeline 42; the outlets of the liquid supply unit 2 and the foaming liquid supply unit 3 are both connected to the inlet of the metering pump 41; and the outlet of the metering pump 41 is connected to the gas-liquid mixer 5 through multiple parallel injection pipelines 42.

[0065] As a preferred structure, such as Figure 2 As shown, the experimental tube 6 is a transparent cylindrical tube sealed at both ends. The two ends of the foam drainage and gas collection tube are detachably installed inside the experimental tube 6 via connectors (detachable design facilitates replacement of the control tube or foam drainage and gas collection tubes with different structural parameters), and the foam drainage and gas collection tube is coaxially arranged with the experimental tube 6. The main body 11 of the foam drainage and gas collection tube is a hollow tubular structure, with its internal cavity forming a main channel. The main channel extends axially along the main body 11 and is sealed and connected to the inlet and outlet ends of the experimental tube 6 via connectors at both ends of the foam drainage and gas collection tube. The main body 11 has a flow channel. The double-helix guide plate 12 includes two guide plates 20, both located within the main channel and spirally and spatially interlocked on the inner wall of the main body 11. Figure 3 , 7 As shown. The double-helix guide plate structure can expand the circumferential range of action of the gas-liquid mixture within the main body 11 of the drainage pipe string, making it easier for the wall-adhering liquid on the lower side of the main body 11 of the drainage pipe string to enter the helical reinforcement area of ​​the guide plate.

[0066] In specific manufacturing, the double helix guide plate 12 adopts a segmented variable pitch structure along its length direction, which includes a dense pitch section, a transition pitch section and a sparse pitch section from the inlet end to the outlet end, so that the main body of the drainage and production tubing forms a continuous process of inlet liquid interception and foaming, middle re-contact foaming and outlet stable foam output.

[0067] like Figure 2 , 3 As shown in Figures 4, 7, and 8, the guide plate 20 has multiple notches 13. The notches 13 are elliptical or oblong on the sidewall of the guide plate 20, and are spaced apart along the length of the guide plate 20. The length of the notches 13 forms an inclined angle with the length of the guide plate 20. The notches 13 penetrate both sides of the guide plate 20, allowing the liquid film or accumulated liquid on the lower side of the horizontal drainage pipe column 11 to pass through the notches 13 and undergo secondary contact and mixing with the mainstream gas. Figure 6 As shown, the inner wall of the main body 11 of the drainage pipe string, the surface of the double helix guide plate 12, the surface of the notch 13, and the surface of the composite step 14 are all provided with a modified nano-SiO2 epoxy double-repellent coating 15. The coating uses epoxy resin as the continuous phase and surface-modified nano-SiO2 particles as the functional phase. It is used to reduce the tendency of water phase and oil phase to wet, hang liquid and adhere on the inner wall of the main body 11 of the drainage pipe string and the surface of the internal guide structure, and to improve the corrosion resistance and wear resistance of the inner surface of the pipe string.

[0068] Further optimize the above structure, such as Figure 3 , 5 As shown in Figure 7, the guide plate 20 is provided with a composite step 14 on the side near the inner wall of the main body 11 of the drainage pipe column. The composite step 14 is a partially convex and concave step structure, and its local cross section is in the shape of a composite step. The working surface of the composite step 14 is divided into a liquid-introducing surface 16, a liquid-stagnating groove 17, a check step surface 18, and a re-entrainment transition surface 19 in sequence. Figure 9 This is a partially enlarged cross-sectional view of the composite step 14 on the guide plate 20. The guide plate 20 with this structure can introduce, briefly retain, and re-entrain the liquid below the horizontal drainage string body 11. This allows the intercepted liquid to re-enter the axially flowing gas-liquid mixture within the main channel of the drainage string body 11 under the guidance of the re-entrainment transition surface 19, and participate in foam formation. The axial gas-liquid mixture flow within the main channel of the drainage string body 11 is distinct from the locally retained liquid in the stagnant groove of the composite step 14, the branched flow within the double-helix guide plate 12, and the localized flow near the notch 13. This clearly indicates that the intercepted liquid, after re-entrainment, re-enters the main flow area of ​​the gas-liquid mixture moving from the inlet to the outlet within the main channel.

[0069] In a specific embodiment of the present invention, the data acquisition unit 10 includes a pressure acquisition module, a flow acquisition module, a liquid level acquisition module, an image acquisition module, a timing module, and a data processing module, used to acquire tube pressure difference, gas-liquid flow rate, foaming liquid injection volume, liquid accumulation height, outlet discharge volume, and image data; the pressure acquisition module includes pressure gauges installed at the inlet and outlet of the experimental tube 6, the flow acquisition module includes a flow meter installed on the outlet injection pipe 42 of the metering pump 41, the liquid level acquisition module is a liquid level gauge on the liquid accumulation height metering unit 7, and the image acquisition module is a camera installed on the side of the experimental tube 6, used to acquire images of the foam discharge gas sampling tube or control tube in the experimental tube 6; the timing module is a timer or computer clock module communicatively connected to the data processing module, used to record the experiment start time, experiment duration, and timestamps corresponding to each acquired data; the data processing module is installed in a computer, and the pressure acquisition module, flow acquisition module, liquid level acquisition module, and image acquisition module are all connected to the computer. The data processing module can store and process experimental data, and generate graphs of liquid height change, liquid phase distribution, foam transport, binary liquid film distribution, and experimental analysis reports.

[0070] This invention also provides an evaluation method for foam drainage gas production in horizontal well sections, comprising the following steps:

[0071] Step 1: Assemble the evaluation device described above. Install the foam drainage and gas sampling tubing inside the horizontal transparent experimental tube 6, ensuring the tubing is coaxial with the tube and the composite step 14 faces the liquid accumulation area below the main flow channel of the horizontal transparent drainage and gas sampling tubing body 11. Check all pipeline interfaces and sealing connections to ensure stable system connections.

[0072] Step 2: Start the data acquisition unit 10 and initialize the acquisition parameters for gas flow rate, liquid flow rate, foaming agent solution injection volume, pressure, liquid accumulation height, and liquid discharge volume;

[0073] Step 3: The experimental liquid and the foaming agent solution are injected into the gas-liquid mixer 5 through the liquid supply unit 2 and the foaming liquid supply unit 3, respectively, and the injection volume is controlled to make the foaming agent mass concentration in the experimental liquid 0.01%-2.0%, preferably 0.05%-0.5%; at the same time, the initial liquid film or local liquid accumulation state is formed in the liquid accumulation area on the lower side of the main channel of the drainage and production string 11, and the initial liquid accumulation height is recorded by the liquid accumulation height metering unit 7, and the initial image and initial operating condition data are recorded by the data acquisition unit 10.

[0074] Step 4: Start the gas supply unit 1 to allow the gas, experimental liquid and foaming agent solution to pass through the gas-liquid mixer 5 to form an initial gas-liquid mixture, which then enters the experimental tube 6.

[0075] Step 5: The gas-liquid mixture flows through the foam drainage and gas collection column in experimental tube 6 to conduct a foam drainage and gas collection experiment. The gas-liquid mixture flows along the segmented variable pitch structure of the double helix guide plate in the foam drainage and gas collection column, and forms a drainage and foaming process under the action of the notch, the composite stepped liquid stagnant section, and the modified nano-SiO2 epoxy double-repellent coating.

[0076] Step 6: Record the changes in liquid height in the experimental tube 6 during the experiment using the liquid height measurement unit 7; separate and measure the outlet gas-liquid mixture using the gas-liquid separation measurement unit 8; collect the separated liquid using the drain collection unit 9; and record the gas flow rate, liquid flow rate, foaming agent solution injection volume, tube pressure difference, outlet drain volume, experimental images, and experimental time data using the data acquisition unit 10.

[0077] Step 7: The experimenters retrieved liquid accumulation height, flow rate, pressure, outlet discharge volume and image data under different times and operating conditions through the data acquisition unit, and generated liquid accumulation height change map, liquid phase distribution map, foam migration map, binary liquid film distribution map, analysis report and experimental log. These are the routine processing, display and recording forms of the acquired data and experimental images, and their specific processes will not be described in detail here.

[0078] Step 8: Change the gas flow rate of gas supply unit 1, the liquid flow rate of liquid supply unit 2, the foaming agent solution concentration of foaming liquid supply unit 3, or the initial liquid accumulation height in experimental tube 6 to re-form the initial liquid film or local liquid accumulation state under the corresponding working conditions, and repeat steps 3 to 7 to obtain drainage foaming performance data under different working conditions.

[0079] Step 9: Replace the foam drainage and gas collection tubing in experimental tube 6 with the control tubing, reinitialize the data acquisition parameters, and repeat steps 3 to 7 under the same experimental conditions; if control data under different operating conditions are required, repeat the experiment according to the parameter change method in step 8, and compare the experimental data of the foam drainage and gas collection tubing with the control tubing to evaluate the drainage and gas collection performance of the foam drainage and gas collection tubing.

[0080] Under the same experimental conditions, the same method is used for foam drainage and gas collection tubing with different sizes, inner diameters, or structural parameters. By repeating the above steps, the drainage and foaming performance data under the corresponding structure can be obtained.

[0081] The use of a horizontally transparent experimental tube (6) can simulate the gas-liquid two-phase flow and the underlying liquid accumulation state within a horizontal well section, facilitating the observation of liquid film distribution, foam migration, and changes in liquid accumulation. During the experiment, the foam drainage and gas production tubing can be replaced with a single-helix tubing, a constant-pitch tubing, a no-notch tubing, a tubing without a composite stepped cross-section, or a control tubing without the modified nano-SiO2 epoxy dual-repellent coating. This structure allows for comparative evaluation of different tubing structures under the same experimental conditions.

[0082] To avoid evaluation results remaining solely at the qualitative observation level, this invention uses data such as continuously collected liquid height, outlet discharge volume, liquid film images, and pipe section pressure differential during the experiment to quantitatively evaluate the foaming effect of the foam drainage gas sampling tubing. Specifically, the liquid height data at different time points inside the horizontally transparent experimental tube 6 is first obtained through the liquid height measurement unit 7; experimental images and pipe section pressure data are obtained through the data acquisition unit 10; and outlet discharge volume data are obtained through the gas-liquid separation measurement unit 8 and the discharge collection unit 9. Then, the above raw data are processed, calculated, and compared to obtain evaluation indicators such as liquid height reduction rate, liquid film area ratio, and discharge efficiency.

[0083] The liquid height reduction rate, liquid film area ratio, and drainage efficiency were calculated from experimental measurements. The liquid height reduction rate reflects the degree of liquid reduction over time, the liquid film area ratio reflects the residual liquid range within the horizontal transparent experimental tube section, and the drainage efficiency reflects the ability of liquid to be carried out of the system within a set time. By repeating the experiment under different gas flow rates, liquid flow rates, foaming agent concentrations, initial liquid heights, and different tube structures, the variation patterns of each evaluation index under different operating conditions can be further compared, thereby characterizing the effects of the double-helix guide plate structure, variable pitch structure, notch, composite stepped cross-section, and modified nano-SiO2 epoxy double-phobic coating on the drainage and foaming effect.

[0084] The specific calculation process for the liquid accumulation height reduction rate, liquid film area ratio, and drainage efficiency is as follows:

[0085] (1) Rate of decrease in fluid accumulation height

[0086] Based on the liquid height data collected by the liquid height measurement unit 7, the liquid height reduction rate is calculated, and its expression is as follows:

[0087]

[0088] in, The height of the liquid in the experimental tube at the initial moment of the experiment. For the experiment to proceed to The height of the fluid at that moment. The rate of decrease in fluid height;

[0089] The liquid height reduction rate is used to characterize the ability of the foam drainage gas sampling string to reduce the liquid accumulation on the lower side of the experimental tube. The larger the value, the more significant the drainage and gas collection effect;

[0090] (2) Percentage of liquid film area

[0091] The experimental images acquired by the data acquisition unit 10 are used to perform grayscale and binarization processing on the liquid film distribution in the experimental tube 6, and the area ratio of the liquid film is calculated. The expression is as follows:

[0092]

[0093] in, Let A represent the area of ​​the liquid film-covered region in the binary liquid film distribution map, and let A be the total area of ​​the image observation region. This represents the percentage of the liquid film area.

[0094] The liquid film area ratio is used to characterize the degree of liquid retention in the experimental tube. The smaller the value, the smaller the area of ​​the remaining liquid film in the experimental tube, and the better the drainage effect of the foam drainage gas sampling column.

[0095] (3) Drainage efficiency

[0096] Based on the outlet discharge volume obtained from the gas-liquid separation metering unit 8 and the discharge collection unit 9, the discharge efficiency is calculated, and its expression is as follows:

[0097]

[0098] in, To set the cumulative volume of discharged liquid collected by the discharge collection unit within the experimental time, This represents the initial total volume of liquid injected into the experiment. For drainage efficiency;

[0099] Drainage efficiency is used to characterize the overall drainage capacity of a foam drainage gas sampling string within a set experimental time. The larger the value, the stronger the liquid discharge capacity of the gas sampling tubing.

[0100] In practical implementation, the data obtained under different working conditions can be used... (The height of the accumulated fluid up to time t during the experiment) (This represents the area of ​​the liquid film-covered region up to time t during the experiment.) , A data table was established based on experimental data such as (volume under different operating conditions over a certain time). Gas flow rate, liquid flow rate, foaming agent concentration, initial liquid accumulation height, pitch parameter, notch diameter, and characteristic dimensions of the composite stepped cross-section were used as independent variables, while liquid accumulation height reduction rate, liquid film area ratio, and drainage efficiency were used as dependent variables for comparative analysis. By performing curve fitting or regression analysis on multiple sets of experimental data, the influence trends of different structural and operating parameters on the drainage foaming effect can be obtained. Therefore, the evaluation method of this invention can not only provide the drainage effect under a single operating condition but also summarize the empirical rules between the structural parameters of the foam drainage gas sampling pipe and the drainage performance based on experimental data, providing a basis for subsequent structural optimization and on-site parameter selection.

[0101] By evaluating the liquid accumulation height reduction rate, liquid film area ratio, and drainage efficiency, the drainage and gas collection performance of foam drainage gas collection tubing under different gas flow rates, liquid flow rates, foaming liquid concentrations, and initial liquid accumulation heights can be comprehensively assessed. For foam drainage gas collection tubing with different structural parameters, the above indicators can also be used for comparative analysis to determine the impact of double-helix guide plates, variable pitch, notches, composite stepped cross-sections, and modified nano-SiO2 epoxy dual-repellent coatings on the drainage and foaming effect.

[0102] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0103] First, this invention expands from a single drainage and extraction tubing string into a complete system, which can simultaneously realize gas supply, liquid supply, foaming liquid supply, metering injection, gas-liquid mixing, horizontal liquid accumulation simulation, liquid drainage foaming, gas-liquid separation metering, and data acquisition, making the device structure more complete.

[0104] Second, the present invention still takes the foam drainage gas production string as its core. The foam drainage gas production string can be detachably installed in a horizontal transparent experimental tube, which can maintain the continuity of flow simulation in the horizontal well section and facilitate the replacement and comparative evaluation of different string structures.

[0105] Third, the present invention enables the liquid on the lower side of the horizontal well section to undergo interception, introduction, short-term retention, re-entrainment, secondary foaming and stable foam output processes through the combined action of the double helix guide plate structure, segmented variable pitch structure, notch, composite stepped liquid stabilization section and modified nano-SiO2 epoxy double hydrophobic coating.

[0106] Fourth, this invention records the changes in liquid accumulation inside the foam drainage gas sampling pipe column through a horizontally transparent experimental tube and a liquid accumulation height measuring unit, so that the evaluation results not only depend on the outlet drainage volume, but also reflect the liquid reduction process inside the pipe section.

[0107] Fifth, this invention obtains the outlet discharge volume, discharge rate, pipe section pressure difference and operating parameters through the gas-liquid separation metering unit, discharge collection unit and data acquisition unit, making the evaluation of discharge foaming performance more continuous, repeatable and comparable.

[0108] Sixth, this invention can evaluate the contributions of the double-helix guide plate structure, variable pitch scheme, notch, composite stepped liquid stagnant section and modified nano-SiO2 epoxy double-hydrophobic coating to the drainage foaming performance by replacing the control column in the experimental tube, providing a basis for subsequent structural optimization and field application.

[0109] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An evaluation device suitable for foam drainage gas production in horizontal well sections, characterized in that: The evaluation device includes a gas supply unit, a liquid supply unit, a foaming agent supply unit, and a horizontally arranged transparent experimental tube. A foam drainage and gas production string or a control string can be detachably installed inside the experimental tube. The gas supply unit, liquid supply unit, and foaming agent supply unit are used to provide the gas, experimental liquid, and foaming agent solution required for the experiment, respectively. A gas-liquid mixer is provided at the inlet end of the experimental tube. The gas supply unit is connected to the gas-liquid mixer. The liquid supply unit and the foaming agent supply unit are connected to the gas-liquid mixer via a conveying unit. The conveying unit is used to control the injection volume, injection rate, and injection ratio of the experimental liquid and foaming agent solution. The gas-liquid mixer is used to mix the gas, experimental liquid, and foaming agent solution to form a gas-liquid mixture. This gas-liquid mixture enters the experimental tube to simulate the gas-liquid two-phase flow and the liquid accumulation state on the lower side within the horizontal well section. The foam drainage and gas collection tubing includes a main body of the drainage and collection tubing and a double-helix guide plate disposed inside it. The double-helix guide plate includes two guide plates, both of which are located in the main channel and are fixed to the inner wall of the main body of the drainage and collection tubing in a spiral spatially interlaced manner. The guide plate is provided with multiple notches, which are spaced apart along the length of the guide plate and penetrate both sides of the guide plate. The guide plate has a composite step on the side near the inner wall of the main body of the drainage pipe string. The surface of the composite step is divided into a liquid-introducing surface, a liquid-stagnating groove, a backflow-preventing step surface and a re-entrainment transition surface in sequence; so that the composite step faces the liquid accumulation area on the lower side of the main flow channel of the drainage pipe string string. The experimental tube is connected to a liquid accumulation height measuring unit, which measures the liquid accumulation height or liquid film thickness at the bottom of the experimental tube. The outlet end of the experimental tube is connected to a gas-liquid separation measuring unit, which separates and measures the gas-liquid mixture after it has passed through the foam drainage gas collection tube. The gas-liquid separation measuring unit is connected to a drainage collection unit, which collects the separated liquid. The delivery unit, gas-liquid mixer, liquid accumulation height metering unit, and experimental tube outlet are all connected to the data acquisition unit to collect gas flow rate, liquid flow rate, foaming agent solution injection volume, tube pressure difference, liquid accumulation height, outlet discharge volume, image data, and experimental time data.

2. The evaluation device for foam drainage gas production in horizontal well sections according to claim 1, characterized in that: The gas supply unit is connected to the gas-liquid mixer via a pressure regulating valve and a gas flow control element; the delivery unit includes a metering pump and an injection pipeline; the outlets of the liquid supply unit and the foaming liquid supply unit are both connected to the inlet of the metering pump; and the outlet of the metering pump is connected to the gas-liquid mixer via multiple parallel injection pipelines.

3. The evaluation device for foam drainage gas production in horizontal well sections according to claim 1, characterized in that: The experimental tube is a transparent cylindrical tube sealed at both ends. The two ends of the foam drainage and gas collection tube are detachably installed inside the experimental tube through connectors, and its inlet and outlet ends are sealed and connected to the inlet and outlet ends of the experimental tube, respectively. The internal cavity of the drainage and gas collection tube forms a main channel. After the gas-liquid mixture enters through the inlet end of the experimental tube, it flows towards the outlet end along the main channel.

4. The evaluation device for foam drainage gas production in horizontal well sections according to claim 1, characterized in that: The double-helix guide plate adopts a segmented variable pitch structure along its length.

5. An evaluation device for foam drainage gas production in horizontal well sections according to claim 1, characterized in that: The length direction of the notch forms an inclined angle with the length direction of the guide plate.

6. An evaluation device for foam drainage gas production in horizontal well sections according to claim 1, characterized in that: The inner wall of the main body of the drainage pipe string, the surface of the double helix guide plate, the surface of the notch, and the surface of the composite step are all provided with a modified nano-SiO2 epoxy double hydrophobic coating.

7. An evaluation device for foam drainage gas production in horizontal well sections according to claim 1, characterized in that: The data acquisition unit includes a pressure acquisition module, a flow acquisition module, a liquid level acquisition module, an image acquisition module, a timing module, and a data processing module. The pressure acquisition module includes pressure gauges installed at the inlet and outlet of the experimental tube. The flow acquisition module includes a flow meter installed on the injection pipeline at the outlet of the metering pump. The liquid level acquisition module is a liquid level gauge on the liquid accumulation height measuring unit. The image acquisition module is located on the side of the experimental tube. The timing module is used to record the start time of the experiment, the duration of the experiment, and the timestamps corresponding to each acquired data. The data processing module is located in a computer. The pressure acquisition module, flow acquisition module, liquid level acquisition module, and image acquisition module are all connected to the computer.

8. An evaluation method applicable to foam drainage gas production in horizontal well sections, characterized in that: Includes the following steps: Step 1: Assemble the evaluation device as described in any one of claims 1-7, and install the foam drainage and gas sampling tubing in the horizontal experimental tube, so that the foam drainage and gas sampling tubing is arranged coaxially with the experimental tube. Step 2: Start the data acquisition unit and initialize the acquisition parameters for gas flow rate, liquid flow rate, foaming agent solution injection volume, pressure, liquid accumulation height, and liquid discharge volume; Step 3: The experimental liquid and the foaming agent solution are injected into the gas-liquid mixer through the liquid supply unit and the foaming liquid supply unit, respectively, and the experimental liquid is formed according to the set ratio. The mass concentration of the foaming agent in the experimental liquid is 0.01%-2.0%. At the same time, an initial liquid film or local liquid accumulation state is formed on the lower side of the experimental tube, and the initial liquid accumulation height is recorded by the liquid accumulation height measurement unit. The initial image and initial operating condition data are recorded by the data acquisition unit. Step 4: Start the gas supply unit to allow the gas, experimental liquid, and foaming agent solution to form an initial gas-liquid mixture through the gas-liquid mixer and enter the experimental tube; Step 5: The gas-liquid mixture flows through the foam drainage and gas collection column in the experimental tube to conduct a foam drainage and gas collection experiment. Step six: Record the changes in the liquid height in the experimental tube during the experiment using the liquid height metering unit; separate and measure the outlet gas-liquid mixture using the gas-liquid separation metering unit; and collect the separated liquid using the liquid collection unit. The data acquisition unit records gas flow rate, liquid flow rate, foaming agent solution injection volume, pipe pressure difference, outlet discharge volume, experimental images, and experimental time data. Step 7: The experimenters retrieved liquid accumulation height, flow rate, pressure, outlet discharge volume and image data under different times and operating conditions through the data acquisition unit, and generated liquid accumulation height change map, liquid phase distribution map, foam migration map, binary liquid film distribution map, analysis report and experimental log; Step 8: Change the gas flow rate of the gas supply unit, the liquid flow rate of the liquid supply unit, the foaming agent solution concentration of the foaming liquid supply unit, or the initial liquid accumulation height in the experimental tube to re-form the initial liquid film or local liquid accumulation state under the corresponding working conditions, and repeat steps 3 to 7 to obtain the drainage foaming performance data under different working conditions. Step 9: Replace the foam drainage and gas collection tubing in the experimental tube with the control tubing, reinitialize the data acquisition parameters, and repeat steps 3 to 7 under the same experimental conditions. If control data under different operating conditions are required, repeat the experiment according to the parameter change method in step 8, and compare the experimental data of the foam drainage and gas collection tubing with the control tubing to evaluate the drainage and gas collection performance of the foam drainage and gas collection tubing.

9. The evaluation method for foam drainage gas production in horizontal well sections according to claim 8, characterized in that: Based on the liquid height data collected by the liquid height metering unit, the liquid height reduction rate is calculated, and its expression is as follows: ； in, The height of the liquid in the experimental tube at the initial moment of the experiment. For the experiment to proceed to The height of the fluid accumulation at that time. The rate of decrease in fluid height; The liquid height reduction rate is used to characterize the ability of the foam drainage gas sampling string to reduce the liquid accumulation on the lower side of the experimental tube. The larger the value, the more significant the drainage and gas collection effect; The experimental images acquired by the data acquisition unit are subjected to grayscale and binarization processing on the liquid film distribution inside the experimental tube, and the area ratio of the liquid film is calculated. The expression is as follows: ； in, Let A represent the area of ​​the liquid film-covered region in the binary liquid film distribution map, and let A be the total area of ​​the image observation region. This represents the percentage of the liquid film area. The liquid film area ratio is used to characterize the degree of liquid retention in the experimental tube. The smaller the value, the smaller the area of ​​the remaining liquid film in the experimental tube, and the better the drainage effect of the foam drainage gas sampling column. The discharge efficiency is calculated based on the outlet discharge volume obtained from the gas-liquid separation metering unit and the discharge collection unit. The expression for this efficiency is: ； in, To set the cumulative volume of discharged liquid collected by the discharge collection unit within the experimental time, This represents the initial total volume of liquid injected into the experiment. For drainage efficiency; Drainage efficiency is used to characterize the overall drainage capacity of a foam drainage gas sampling string within a set experimental time. The larger the value, the stronger the liquid discharge capacity of the gas sampling tubing.

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