Experimental device and method for evaluating pulverized coal settlement of coal bed gas horizontal shaft

Abstract

The invention belongs to the technical field of coal bed gas development simulation experiments, and particularly relates to a coal bed gas horizontal shaft pulverized coal sedimentation evaluation experiment device and method. The experiment device comprises a horizontal shaft simulation system which comprises a bent horizontal shaft and a support; a gas-liquid mixer is arranged at an inlet of the bent horizontal shaft; the gas injection system at least comprises a gas cylinder, and the gas cylinder is connected to the gas inlet of the gas-liquid mixer through a first pipeline; the coal liquid injection system comprises a coal liquid stirrer, the coal liquid stirrer is used for uniformly stirring coal powder and formation water, and an outlet of the coal liquid stirrer is connected to a liquid inlet of the gas-liquid mixer through a second pipeline; an outlet of the bent horizontal shaft is connected with a gas-liquid separation device; and the liquid holdup measuring system is arranged corresponding to the bent horizontal shaft. And the state that a mixture of coal bed gas, pulverized coal and formation water under different pressures enters a bent horizontal shaft can be accurately simulated.

Description

Technical Field

[0001] The invention belongs to the technical field of coalbed methane development simulation experiments, and specifically relates to a coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device and method. Background Art

[0002] Coalbed methane is a self-generated and self-stored unconventional natural gas that is formed in coal seams and stored in coal seams. It is mainly composed of methane (more than 95%) and a very small amount of heavier hydrocarbons (mostly ethane and propane), as well as nitrogen and carbon dioxide. As a clean energy source, coalbed methane naturally has low-carbon properties. my country's coalbed methane resources are extremely rich, but they are generally secondary resources. In addition, they are often in low-pressure, low-porosity and low-permeability reservoirs, making coalbed methane difficult to mine. At the same time, coalbed methane is enriched in coal seams. When mining coal resources, coal and coalbed methane outburst accidents are serious, and are often accompanied by secondary disasters such as fire, explosion, and poisoning.

[0003] In order to achieve "increased reserves and increased production" of oil and gas and reduce secondary disasters during coal mining, it is necessary to first extract coalbed methane resources. Horizontal well fracturing transformation is the most core technical means to achieve efficient development of unconventional coalbed methane resources. However, the elastic modulus of coal seams is low and they are fragile. After large-scale hydraulic fracturing, coal reservoirs will produce a large amount of coal powder (including proppants); at the same time, coal seams are usually water-rich reservoirs. During the fracturing fluid return and drainage stage, coal powder and water are easily mixed together to form a viscous coal slurry and enter the wellbore under the pressure of the reservoir. Moreover, since horizontal wellbores often fluctuate with coal seams, coal powder may accumulate in the depressions of the wellbore, blocking the wellbore, seriously restricting the outflow of gas and liquid in the wellbore, and affecting the production of coalbed methane; and the existing physical experimental models and simulation schemes cannot simulate the migration, sedimentation, and blockage of coal powder in horizontal wellbores with complex fluctuation angles.

[0004] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Invention content

[0005] The purpose of the present invention is to provide a coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device and method, so as to at least solve the above-mentioned problems existing in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] An experimental device for evaluating coal dust settling in a coalbed methane horizontal wellbore, the experimental device comprising:

[0008] A horizontal wellbore simulation system, wherein the horizontal wellbore simulation device comprises a curved horizontal wellbore and a bracket, wherein the curved horizontal wellbore is supported by the bracket, and the bending angle and curvature radius of the curved horizontal wellbore are proportionally reduced according to the wellbore trajectory of an actual coalbed methane horizontal well;

[0009] A gas-liquid mixer is provided at the entrance of the curved horizontal wellbore;

[0010] A gas injection system, the gas injection system at least comprising a gas cylinder, the gas cylinder being connected to the gas inlet of the gas-liquid mixer through a first pipeline, and being used for inputting gas into the curved horizontal wellbore;

[0011] A coal liquid injection system, the coal liquid injection system at least comprising a coal liquid agitator, the coal liquid agitator being used to evenly agitate coal powder and formation water, the outlet of the coal liquid agitator being connected to the liquid inlet of the gas-liquid mixer through a second pipeline, and being used to input the coal liquid mixture into the curved horizontal wellbore;

[0012] A gas-liquid separation device is connected to the outlet of the curved horizontal wellbore, and the gas-liquid separation device is used to separate the gas and coal-liquid mixture rushing out of the curved horizontal wellbore;

[0013] A liquid holdup rate measurement system is provided corresponding to a curved horizontal wellbore and is used to detect the gas-liquid ratio set in the curved horizontal wellbore.

[0014] As described above, the coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device, preferably, the liquid holdup measurement system includes a plurality of conductivity measurement units, each of the conductivity measurement units includes 4 conductive rings, and each conductive ring is embedded on the inner wall of the curved horizontal wellbore;

[0015] Among them, the two conductive rings located on the outside constitute a voltage electrode pair, and the two conductive rings located on the inside constitute a current electrode pair. A constant voltage is applied to the voltage electrode pair to form an electric field, and then the current between the current electrode pair is measured. The conductivity to be measured is obtained by the ratio between the constant voltage and the measured current.

[0016] In the coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device as described above, preferably, a pressure controller and a valve are sequentially arranged on the first pipeline, and the pressure controller is used to control the flow rate and pressure of the gas released from the gas cylinder, so as to input gas with different flow rates and pressures into the curved horizontal wellbore.

[0017] In the coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device as described above, preferably, constant pressure and constant speed pumps are sequentially arranged on the second pipeline, and the constant pressure and constant speed pumps are used to input the coal-liquid mixture into the curved horizontal wellbore at a set pressure and flow rate.

[0018] In the above-mentioned coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device, preferably, a first gas flow meter is also provided on the first pipeline, and the first gas flow meter is located downstream of the valve;

[0019] The gas outlet of the gas-liquid separation device is connected to a second gas flow meter.

[0020] In the coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device as described above, preferably, a liquid flow meter is also provided on the second pipeline, and the liquid flow meter is located downstream of the constant pressure and constant speed pump.

[0021] As described above, in the coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device, preferably, a dryer is provided at the liquid outlet of the gas-liquid separation device, and the dryer is used to dry the coal-liquid mixture separated from the gas-liquid separation device into coal powder.

[0022] The coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device as described above, preferably, a first check valve is further provided on the first pipeline, and the first check valve is located upstream of the gas-liquid mixer;

[0023] A second check valve is also provided on the second pipeline, and the second check valve is located upstream of the gas-liquid mixer.

[0024] The above-mentioned coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device, preferably, the experimental device also includes a coal powder concentration monitoring system, the coal powder concentration monitoring system includes a plurality of monitoring units, and the plurality of monitoring units are distributed at different positions on the curved horizontal wellbore; the curved horizontal wellbore is made of transparent material;

[0025] The monitoring unit includes a light source transmitting end and a receiving end. The light source transmitting end is used to vertically transmit a beam of parallel light toward the curved horizontal wellbore. After the parallel light passes through the coal powder, scattering and projection reactions will occur.

[0026] The receiving end includes multiple scattered light receivers and multiple transmitted light receivers. The scattered light receivers are used to measure the scattered light intensity passing through the curved horizontal wellbore, and the transmitted light receivers are used to measure the transmitted light intensity passing through the curved horizontal wellbore. The ratio of the scattered light intensity to the transmitted light intensity is proportional to the coal powder content.

[0027] The present application also provides a coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental method, the experimental method uses the above-mentioned coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device, and the experimental method includes the following steps:

[0028] Step 1, prepare coal powder and mix it with formation water for experiment; introduce the coal powder and formation water into a coal liquid agitator and stir them evenly;

[0029] Step 2, constructing a curved horizontal wellbore in proportion to the actual wellbore trajectory of the coalbed methane horizontal well;

[0030] Step 3, adjusting the constant pressure and constant speed pump so that the coal-liquid mixture is injected into the curved horizontal wellbore through the gas-liquid mixer at a set flow rate;

[0031] Step 4, adjusting the pressure controller so that the gas enters the curved horizontal wellbore through the gas-liquid mixer at a set pressure;

[0032] Step 5, the gas, formation water and coal powder flow from the other end of the curved horizontal wellbore to the gas-liquid separation device;

[0033] Step 6: monitor the gas-liquid ratio at different positions in the curved horizontal wellbore by using a liquid holdup measurement device; detect the coal powder content at different positions in the curved horizontal wellbore by using a coal powder concentration monitoring system;

[0034] Step 7, a high-speed camera is arranged on one side of the curved horizontal wellbore, and the settling phenomenon of coal powder in the curved horizontal wellbore is monitored in real time by the camera;

[0035] Step 8, drying the coal-liquid mixture separated in the gas-liquid separation device, then measuring the dried product, and testing the components in the dried product using an X-ray diffractometer;

[0036] Step 9, change the parameters in the above steps and repeat the above steps to obtain the precipitation position and precipitation amount of coal powder in the curved horizontal wellbore under the gas flow rate, pressure and gas-liquid ratio parameters, as well as the change law of the amount of coal powder flowing out of the curved horizontal wellbore and the coal powder composition.

[0037] Beneficial effects:

[0038] In the experimental device, a curved horizontal wellbore is made by proportionally reducing the curved trajectory of the actual coalbed methane horizontal wellbore to simulate the curved and undulating state of the horizontal wellbore under actual working conditions, so that the experimental results are closer to the actual working conditions of coalbed methane extraction; at the same time, a gas-liquid mixer is set at the entrance of the curved horizontal wellbore, and the gas provided by the gas injection system and the coal-liquid mixture provided by the coal-liquid injection system are mixed by the gas-liquid mixer and enter the curved horizontal wellbore, so as to more accurately simulate the state of coalbed methane, coal powder and formation water mixtures of different pressures entering the curved horizontal wellbore, so as to ensure the reliability and accuracy of the experimental results; and a liquid holdup measurement system is set in the curved horizontal wellbore, which can monitor the gas-liquid ratio at the set position of the curved horizontal wellbore in real time, so as to facilitate the observation and recording of the coal powder sedimentation law in the curved horizontal wellbore. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings constituting part of the present application are used to provide a further understanding of the invention. The exemplary embodiments and descriptions of the invention are used to explain the invention and do not constitute an improper limitation on the invention. Among them:

[0040] Figure 1 A schematic diagram of a coal bed methane horizontal wellbore coal dust sedimentation evaluation experimental device according to an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the structure of a liquid holdup monitoring system according to an embodiment of the present invention;

[0042] Figure 3 A schematic structural diagram of a coal powder concentration monitoring system according to an embodiment of the present invention.

[0043] In the figure: 1. gas cylinder; 2. pressure controller; 3. valve; 4. first gas flowmeter; 5. first check valve; 6. gas-liquid mixer; 7. liquid holdup measurement system; 71. current electrode pair; 72. voltage electrode pair; 8. coal powder concentration monitoring system; 81. light source transmitting end; 82. scattered light receiver; 83. transmitted light receiver; 9. curved horizontal wellbore; 10. gas-liquid separation device; 11. dryer; 12. electronic balance; 13. second gas flowmeter; 14. second check valve; 15. liquid flowmeter; 16. constant pressure and constant speed pump; 17. coal liquid agitator; 18. water tank. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0045] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixedly connected or detachably connected; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0046] The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0047] According to the specific embodiments of the present invention, Figure 1-3 As shown, the present invention provides a coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device, the experimental device comprises:

[0048] The horizontal wellbore simulation system includes a curved horizontal wellbore 9 and a bracket, and the curved horizontal wellbore 9 is supported by the bracket. The bending angle and curvature radius of the curved horizontal wellbore 9 are proportionally reduced according to the wellbore trajectory of the actual coalbed methane horizontal well. In this embodiment, the curved horizontal wellbore 9 is composed of a plurality of short-joint pipes with curved structures. Such a configuration makes the short-joint pipes easier to manufacture. Two adjacent short-joint pipes are formed by corresponding threaded hoops to ensure the tightness and stability of the curved horizontal wellbore 9. Among them, the short-joint pipe is made of polymethyl methacrylate material, which has the characteristics of transparency and high hardness.

[0049] A gas-liquid mixer 6 is provided at the entrance of the curved horizontal wellbore 9;

[0050] The gas injection system at least comprises a gas cylinder 1, which is connected to the gas inlet of the gas-liquid mixer 6 through a first pipeline and is used to input gas into the curved horizontal wellbore 9; in this embodiment, the gas contained in the gas cylinder 1 is nitrogen, which is used to simulate formation gas;

[0051] The coal liquid injection system at least includes a coal liquid agitator 17, which is used to mix coal powder and formation water evenly. The outlet of the coal liquid agitator 17 is connected to the liquid inlet of the gas-liquid mixer 6 through a second pipeline, and is used to input the coal liquid mixture into the curved horizontal wellbore 9. In this embodiment, a water tank 18 is provided upstream of the coal liquid mixer, and the water tank 18 is used to store formation water.

[0052] A gas-liquid separation device 10 is connected to the outlet of the curved horizontal wellbore 9 , and the gas-liquid separation device 10 is used to separate the gas and coal-liquid mixture rushing out of the curved horizontal wellbore 9 .

[0053] The liquid holdup rate measurement system 7 is set corresponding to the curved horizontal wellbore 9 and is used to detect the gas-liquid ratio set in the curved horizontal wellbore 9.

[0054] In the experimental device, a curved horizontal wellbore 9 is made by proportionally reducing the curved trajectory of the actual coalbed methane horizontal wellbore to simulate the curved and undulating state of the horizontal wellbore under actual working conditions, so that the experimental results are closer to the actual working conditions of coalbed methane extraction; at the same time, a gas-liquid mixer 6 is set at the entrance of the curved horizontal wellbore 9, and the gas provided by the gas injection system and the coal-liquid mixture provided by the coal-liquid injection system are mixed by the gas-liquid mixer 6 and enter the curved horizontal wellbore 9, so as to more accurately simulate the state of coalbed methane, coal powder and formation water mixtures of different pressures entering the curved horizontal wellbore 9, so as to ensure the reliability and accuracy of the experimental results; and a liquid holdup measurement system 7 is set in the curved horizontal wellbore 9, which can monitor the gas-liquid ratio at a set position of the curved horizontal wellbore 9 in real time, so as to facilitate the observation and recording of the coal powder sedimentation law in the curved horizontal wellbore 9.

[0055] In this embodiment, the coal powder is the coal powder collected from the actual coalbed methane wellhead. At the same time, the mineralization, viscosity, ion type and concentration of the formation water collected from the actual coalbed methane wellhead are analyzed, and the experimental water is modulated based on this.

[0056] The liquid holdup measurement system 7 includes a plurality of conductivity measurement units, each of which includes four conductive rings, and each conductive ring is embedded in the inner wall of the curved horizontal wellbore 9. In this embodiment, the conductive rings of the annular structure can surround the inner wall of the wellbore. As long as there is water flowing through the wellbore, the water flow will conduct the conductive rings, thereby facilitating the improvement of the sensitivity of the liquid holdup measurement system 7. The conductive rings are embedded in the inner wall of the curved horizontal wellbore 9, so as not to affect the circulation of the fluid in the horizontal wellbore as much as possible.

[0057] Among them, the two conductive rings located on the outside constitute a voltage electrode pair 72, and the two conductive rings located on the inside constitute a current electrode pair 71. A constant voltage is applied to the voltage electrode pair 72 to form an electric field, and then the current between the current electrode pair 71 is measured. The conductivity to be measured is obtained by the ratio between the constant voltage and the measured current.

[0058] In one embodiment of the present application, the voltage electrode pair 72 is an excitation electrode pair, and the current electrode pair 71 is a measurement electrode pair; the polarization effect will cause charge accumulation on the electrode surface, thereby affecting the accuracy of the measurement result. By setting the current electrode and the voltage electrode separately, the polarization effect on the measurement electrode pair can be effectively avoided, the interference of the polarization effect can be reduced, and the measurement accuracy can be improved.

[0059] Moreover, the four-electrode structure in this application makes the conductivity sensor have higher sensitivity and stronger anti-pollution ability. In liquid, pollutants may adhere to the electrode surface and affect the measurement results; and in this application, many minerals are dissolved in the water coming out of the coal seam, which is easy to precipitate. This application uses 4 electrodes, and the electric field formed can inhibit the precipitation of minerals, so as to facilitate long-term use. That is, the four-electrode structure can reduce the impact of pollutants on the measurement and maintain the stability of the measurement.

[0060] In other embodiments of the present application, a conductivity measuring unit is composed of four conductive rings, which are embedded in the inner wall of the curved horizontal wellbore 9. Every two conductive rings form a group of conductivity sensors. Multiple groups of conductivity sensors are connected in parallel with a fixed resistor and powered by a DC power supply.

[0061] Among them, the greater the liquid holdup between each group of conductivity sensors, the higher the liquid level and the smaller the resistance, then the higher the voltage value across the custom resistor. That is, by measuring the voltage across the fixed resistor, the liquid holdup between the conductivity sensors can be obtained.

[0062] A pressure controller 2 and a valve 3 are sequentially arranged on the first pipeline. The pressure controller 2 is used to control the flow rate and pressure of the gas released from the gas cylinder 1 so as to input gas with different flow rates and pressures into the curved horizontal wellbore 9.

[0063] In one embodiment of the present application, the on-off of the first pipeline is controlled by a valve 3, and the flow rate and pressure of the gas released from the gas cylinder 1 are adjusted by a pressure controller 2, so as to simulate the situation where coalbed methane with different pressures enters the curved horizontal wellbore 9 under different formation pressures, thereby obtaining the change pattern of the precipitation position and precipitation amount of coal powder in the curved horizontal wellbore 9 under different flow rates, pressures and gas-liquid ratio parameters.

[0064] The second pipeline is provided with a constant pressure and constant speed pump 16 in sequence, and the constant pressure and constant speed pump 16 is used to input the coal-liquid mixture into the curved horizontal wellbore 9 at a set pressure and flow rate.

[0065] In one embodiment of the present application, a constant pressure and constant speed pump 16 is used to transport the coal-liquid mixture to a curved horizontal wellbore 9 at a set pressure and flow rate, so as to simulate a state in which the coal-liquid mixture enters a completely horizontal wellbore and settles under different formation pressures.

[0066] The first pipeline is also provided with a first gas flowmeter 4, which is located downstream of the valve 3; the gas outlet of the gas-liquid separation device 10 is connected to a second gas flowmeter 13. In one embodiment of the present application, the first gas flowmeter 4 is used to detect the total flow rate of gas delivered by the gas cylinder 1 to the curved horizontal wellbore 9, and the second gas flowmeter 13 is used to detect the total flow rate of gas discharged from the curved horizontal wellbore 9, so that the gas passing rate in the horizontal wellbore under different coal powder settling conditions can be obtained, thereby determining the law between different coal powder settling conditions and coalbed methane production rate.

[0067] The second pipeline is also provided with a liquid flow meter 15, which is located downstream of the constant pressure constant speed pump 16. In one embodiment of the present application, the liquid flow meter 15 is used to detect the total flow of the coal-liquid mixture transported by the coal-liquid agitator 17 to the curved horizontal wellbore 9.

[0068] A dryer 11 is provided at the liquid outlet of the gas-liquid separation device 10 , and the dryer 11 is used to dry the coal-liquid mixture separated from the gas-liquid separation device 10 into coal powder.

[0069] In one embodiment of the present application, an electronic scale 12 is provided downstream of the dryer 11. The mass of the dried coal powder is measured by the electronic scale 12. By comparing the total flow rate of the coal-liquid mixture entering the completely horizontal wellbore measured by the liquid flowmeter 15 and the coal-liquid mixing ratio in the coal-liquid agitator 17, the coal powder sedimentation amount in the completely horizontal wellbore and the composition ratio of the sedimentated coal powder can be obtained.

[0070] A first check valve 5 is also provided on the first pipeline, and the first check valve 5 is located upstream of the gas-liquid mixer 6 ; a second check valve 14 is also provided on the second pipeline, and the second check valve 14 is located upstream of the gas-liquid mixer 6 .

[0071] In one embodiment of the present application, the first check valve 5 is located on the first pipeline between the first gas flow meter 4 and the gas-liquid mixer 6, and the second check valve 14 is located on the second pipeline between the liquid flow meter 15 and the gas-liquid mixer 6. By arranging check valves in both the first pipeline and the second pipeline, it is used to prevent the internal materials of the curved horizontal wellbore 9 from returning into the first pipeline and the second pipeline after blockage occurs. This can not only ensure the accuracy of the experiment, but also avoid damage to the experimental equipment on the first pipeline and the second pipeline.

[0072] The experimental device also includes a coal powder concentration monitoring system 8, which includes a plurality of monitoring units, and the plurality of monitoring units are distributed at different positions on a curved horizontal wellbore 9; the curved horizontal wellbore 9 is made of transparent material;

[0073] The monitoring unit includes a light source transmitting end 81 and a receiving end. The light source transmitting end 81 is used to vertically transmit a beam of parallel light toward the curved horizontal shaft 9. After the parallel light passes through the coal powder, scattering and projection reactions will occur.

[0074] The receiving end includes multiple scattered light receivers 82 and multiple transmitted light receivers 83. The scattered light receivers are used to measure the scattered light intensity passing through the curved horizontal wellbore 9, and the transmitted light receivers 83 are used to measure the transmitted light intensity passing through the curved horizontal wellbore 9. The ratio of the scattered light intensity to the transmitted light intensity is proportional to the coal powder content.

[0075] In one embodiment of the present application, the scattered light receiver 82 and the transmitted light receiver 83 are distributed at an angle of 11°, and the ratio (σ) of the scattered light intensity to the transmitted light intensity is proportional to the coal powder content. σ can be used to monitor the change pattern of coal seam concentration in the fluid under different conditions and at different locations.

[0076] The present application also provides a coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental method, the experimental method uses the above-mentioned coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device, and the experimental method includes the following steps:

[0077] Step 1, prepare coal powder and mix it with formation water for experiment; introduce the coal powder and formation water into the coal liquid agitator 17 and mix them evenly;

[0078] Step 2, constructing a curved horizontal wellbore 9 in proportion to the actual wellbore trajectory of the coalbed methane horizontal well;

[0079] Step 3, adjusting the constant pressure and constant speed pump 16 so that the coal-liquid mixture is injected into the curved horizontal wellbore 9 via the gas-liquid mixer 6 at a set flow rate;

[0080] Step 4, adjusting the pressure controller 2 so that the gas enters the curved horizontal wellbore 9 through the gas-liquid mixer 6 at a set pressure;

[0081] Step 5, gas, formation water and coal powder flow from the other end of the curved horizontal wellbore 9 to the gas-liquid separation device 10;

[0082] Step 6: monitor the gas-liquid ratio at different positions in the curved horizontal wellbore 9 by means of a liquid holdup measurement device; detect the coal powder content at different positions in the curved horizontal wellbore 9 by means of a coal powder concentration monitoring system 8;

[0083] Step 7, a high-speed camera is arranged on one side of the curved horizontal shaft 9, and the sedimentation phenomenon of the coal powder in the curved horizontal shaft 9 is monitored in real time by the camera;

[0084] Step 8, drying the coal-liquid mixture separated in the gas-liquid separation device 10, then measuring the dried product, and testing the components in the dried product using an X-ray diffractometer;

[0085] Step 9, change the parameters in the above steps, and repeat the above steps to obtain the precipitation position and precipitation amount of coal powder in the curved horizontal wellbore 9 under the gas flow rate, pressure and gas-liquid ratio parameters, as well as the change law of the amount of coal powder flowing out of the curved horizontal wellbore 9 and the coal powder composition.

[0086] It should be understood that the above description is merely exemplary and the embodiments of the present application do not limit this.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device, characterized in that: The experimental device includes: A horizontal wellbore simulation system, wherein the horizontal wellbore simulation device comprises a curved horizontal wellbore and a bracket, wherein the curved horizontal wellbore is supported by the bracket, and the bending angle and curvature radius of the curved horizontal wellbore are proportionally reduced according to the wellbore trajectory of an actual coalbed methane horizontal well; A gas-liquid mixer is provided at the entrance of the curved horizontal wellbore; A gas injection system, the gas injection system at least comprising a gas cylinder, the gas cylinder being connected to the gas inlet of the gas-liquid mixer through a first pipeline, and being used for inputting gas into the curved horizontal wellbore; A coal liquid injection system, the coal liquid injection system at least comprising a coal liquid agitator, the coal liquid agitator being used to evenly agitate coal powder and formation water, the outlet of the coal liquid agitator being connected to the liquid inlet of the gas-liquid mixer through a second pipeline, and being used to input the coal liquid mixture into the curved horizontal wellbore; A gas-liquid separation device is connected to the outlet of the curved horizontal wellbore, and the gas-liquid separation device is used to separate the gas and coal-liquid mixture rushing out of the curved horizontal wellbore; A liquid holdup measurement system is provided corresponding to a curved horizontal wellbore and is used to detect the gas-liquid ratio set in the curved horizontal wellbore.

2. The coal bed methane horizontal wellbore coal powder sedimentation evaluation experimental device according to claim 1 is characterized in that: The liquid holdup measurement system includes a plurality of conductivity measurement units, each of which includes four conductive rings, and each conductive ring is embedded on the inner wall of the curved horizontal wellbore; Among them, the two conductive rings located on the outside constitute a voltage electrode pair, and the two conductive rings located on the inside constitute a current electrode pair. A constant voltage is applied to the voltage electrode pair to form an electric field, and then the current between the current electrode pair is measured. The conductivity to be measured is obtained by the ratio between the constant voltage and the measured current.

3. The coal bed methane horizontal wellbore coal powder sedimentation evaluation experimental device according to claim 2 is characterized in that: The first pipeline is provided with a pressure controller and a valve in sequence, and the pressure controller is used to control the flow rate and pressure of the gas released from the gas cylinder, so as to input gas with different flow rates and pressures into the curved horizontal wellbore.

4. The coal bed methane horizontal wellbore coal powder sedimentation evaluation experimental device according to claim 3 is characterized in that: The second pipeline is provided with constant pressure and constant speed pumps in sequence, and the constant pressure and constant speed pumps are used to input the coal-liquid mixture into the curved horizontal wellbore at a set pressure and flow rate.

5. The coal bed methane horizontal wellbore coal powder sedimentation evaluation experimental device according to claim 4, characterized in that: The first pipeline is also provided with a first gas flow meter, and the first gas flow meter is located downstream of the valve; The gas outlet of the gas-liquid separation device is connected to a second gas flow meter.

6. The coal bed methane horizontal wellbore coal powder sedimentation evaluation experimental device according to claim 5, characterized in that: The second pipeline is also provided with a liquid flow meter, and the liquid flow meter is located downstream of the constant pressure and constant speed pump.

7. The coal bed methane horizontal wellbore coal powder sedimentation evaluation experimental device according to claim 6, characterized in that: A dryer is provided at the liquid outlet of the gas-liquid separation device, and the dryer is used to dry the coal-liquid mixture separated from the gas-liquid separation device into coal powder.

8. The coal bed methane horizontal wellbore coal dust sedimentation evaluation experimental device according to claim 2, characterized in that: A first check valve is also provided on the first pipeline, and the first check valve is located upstream of the gas-liquid mixer; A second check valve is also provided on the second pipeline, and the second check valve is located upstream of the gas-liquid mixer.

9. The coal bed methane horizontal wellbore coal dust sedimentation evaluation experimental device according to claim 2, characterized in that: The experimental device also includes a coal powder concentration monitoring system, which includes a plurality of monitoring units, and the plurality of monitoring units are distributed at different positions on the curved horizontal wellbore; the curved horizontal wellbore is made of transparent material; The monitoring unit includes a light source transmitting end and a receiving end. The light source transmitting end is used to vertically transmit a beam of parallel light toward the curved horizontal wellbore. After the parallel light passes through the coal powder, scattering and projection reactions will occur. The receiving end includes multiple scattered light receivers and multiple transmitted light receivers. The scattered light receivers are used to measure the scattered light intensity passing through the curved horizontal wellbore, and the transmitted light receivers are used to measure the transmitted light intensity passing through the curved horizontal wellbore. The ratio of the scattered light intensity to the transmitted light intensity is proportional to the coal powder content.

10. An experimental method for evaluating coal dust sedimentation in a coalbed methane horizontal wellbore, characterized in that: The experimental method uses the coalbed methane horizontal wellbore coal powder sedimentation evaluation experimental device according to any one of claims 1 to 9, and the experimental method comprises the following steps: Step 1, prepare coal powder and mix it with formation water for experiment; introduce the coal powder and formation water into a coal liquid agitator and stir them evenly; Step 2, constructing a curved horizontal wellbore in proportion to the actual wellbore trajectory of the coalbed methane horizontal well; Step 3, adjusting the constant pressure and constant speed pump so that the coal-liquid mixture is injected into the curved horizontal wellbore through the gas-liquid mixer at a set flow rate; Step 4, adjusting the pressure controller so that the gas enters the curved horizontal wellbore through the gas-liquid mixer at a set pressure; Step 5, the gas, formation water and coal powder flow from the other end of the curved horizontal wellbore to the gas-liquid separation device; Step 6: monitor the gas-liquid ratio at different positions in the curved horizontal wellbore by using a liquid holdup measurement device; detect the coal powder content at different positions in the curved horizontal wellbore by using a coal powder concentration monitoring system; Step 7, a high-speed camera is arranged on one side of the curved horizontal wellbore, and the settling phenomenon of coal powder in the curved horizontal wellbore is monitored in real time by the camera; Step 8, drying the coal-liquid mixture separated in the gas-liquid separation device, then measuring the dried product, and testing the components in the dried product using an X-ray diffractometer; Step 9, change the parameters in the above steps and repeat the above steps to obtain the precipitation position and precipitation amount of coal powder in the curved horizontal wellbore under the gas flow rate, pressure and gas-liquid ratio parameters, as well as the change law of the amount of coal powder flowing out of the curved horizontal wellbore and the coal powder composition.

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