An experimental device and method for simulating hydrate radio frequency deblocking in a production gas well wellbore

Abstract

The application discloses a kind of simulation production gas well wellbore hydrate radio frequency deblocking experimental device and method, including radio frequency transmitting system, gas injection system, liquid injection system, simulation wellbore deblocking system, data monitoring and processing system.The application can realize simulation gas well production working condition, by changing frequency current monitoring hydrate decomposition situation of jamming position, further obtain hydrate jamming block decomposition duration and gas-liquid flow under different radio frequency current, calculate the decomposition rate of wellbore hydrate, evaluate the deblocking effect of radio frequency heating under different gas-liquid ratio conditions.Simulation deblocking effect is good, and operability is strong.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrate plugging removal in gas well bore, and particularly to a hydrate plugging removal device based on radio frequency heating. BACKGROUND

[0002] Natural gas hydrate is a non-stoichiometric cage-shaped crystalline substance formed by gas molecules and water molecules under high pressure and low temperature conditions. In the production process, natural gas is produced in the gas well (gas storage well), and the wellbore near the bottom is in a high temperature and high pressure state. As the gas rises in the wellbore, the temperature decreases significantly. Under the condition of low temperature and high pressure, water and natural gas are prone to form hydrates at the position close to the wellhead, the gas production channel of the reservoir, the wellbore, the blowout preventer (BOP), the choke pipeline and other parts, causing wellbore plugging, reducing gas production efficiency or even stopping production. Therefore, plugging removal measures must be taken to restore normal production.

[0003] At present, the measures for hydrate plugging removal in the wellbore include: (1) physical plugging removal method, which crushes the hydrate plugging block by electrically rotating a conical pulverizer, or uses a vibration rod to knock the inner wall of the wellbore to make the hydrate break and fall. However, the plugging removal takes a long time and cannot achieve complete plugging removal. (2) Chemical agent plugging removal method, which changes the activity of hydrate by adding different proportions of plugging removal agents to change the phase change characteristics of hydrate, so as to achieve the effect of plugging removal. However, the dosage of ordinary plugging removal agent is huge, and it has a great impact on the wellbore and the production environment, such as methanol (toxic); the production cost of new polymer inhibitor is extremely high, which is not economical. (3) Heating method, which heats the plugged part to above the hydrate phase equilibrium temperature to make the hydrate decompose and remove the plug. It includes casing bundle heating, electric heating tape heating, direct electric heating, etc. However, the traditional heating method has the disadvantages of slow heating rate, large heat loss, immature technology, high energy consumption and low economy. In contrast, radio frequency heating method can quickly heat as needed, and it has shown its effectiveness in heavy oil. Radio frequency is a high-frequency alternating electromagnetic wave, and radio frequency heating is to cause the rapid rotation of polar molecules in the material by a rapidly alternating electric field, and generate heat by friction. SUMMARY

[0004] The present application provides a simulation production gas well bore hydrate radio frequency plugging removal experimental device and method, which aims to provide an experimental device and method for evaluating the plugging removal effect of radio frequency heating.

[0005] To solve the above problems, the technical scheme adopted by the present application is:

[0006] The application discloses an experimental device for simulating hydrate radio frequency deblocking of a gas well, which comprises a radio frequency generating system, a hydrate plugging deblocking system, a gas injection system, a liquid injection system, a waste gas and liquid recovery system and a data monitoring and processing system.

[0007] Optionally or preferably, the radio frequency generating system comprises a radio frequency transmitting motor, a circulating refrigerator, a water-cooled circulating pipeline, a current matcher, a coaxial cable, a ring-shaped electrode ring and an electrode plate; one end of the radio frequency transmitting motor is connected with the circulating refrigerator through the water-cooled circulating pipeline; the other end of the radio frequency transmitting motor is connected with the current matcher; the current matcher is connected with the ring-shaped electrode ring and the electrode plate through the coaxial cable; an electromagnetic valve and a safety valve are arranged on the water-cooled circulating pipeline; the circulating refrigerator, the radio frequency transmitting motor and the current matcher are connected with a whole device control box and a computer.

[0008] Optionally or preferably, the radio frequency transmitting motor is a transistor type radio frequency transmitting motor, which comprises a signal source, a power divider, a driving module, a power amplifier module and a synthesizer.

[0009] Optionally or preferably, the hydrate plugging deblocking system comprises a wellbore with a visual window, a hydrate plugging block, a retractable alloy frame body with a built-in resistance probe, a perforated baffle for placing the hydrate plugging block, a temperature probe, a pressure probe, a resistivity tester, a sealing flange, a real-time camera and a shielding box; the two ends of the wellbore are provided with the ring-shaped electrode ring and the electrode plate, and the wellbore is provided with the visual window; the hydrate plugging block is a standard cylindrical hydrate, which is placed in the retractable alloy frame body at the upper end and the lower end and is placed on the perforated baffle as a whole; the retractable alloy frame body is provided with the probes of the resistivity tester at the upper end and the lower end; the temperature probe and the pressure probe are optical fiber temperature sensor probes and optical fiber pressure sensor probes respectively; the temperature probe is arranged near the sealing flange in the wellbore and on the upper side of the hydrate plugging block; the shielding box is made of stainless steel and is additionally provided with an outer thermal insulation layer; the real-time camera faces the hydrate plugging block; the retractable alloy frame body is connected with the resistivity tester; the temperature probe and the pressure probe are connected with a temperature sensor and a pressure sensor respectively; the shielding box is connected with the current matcher through the coaxial cable and is sealed and protected by copper foil; the shielding box is grounded; the temperature sensor, the pressure sensor, the resistivity tester and the real-time camera are connected with the whole device control box and the computer.

[0010] Optionally or preferably, the gas injection system comprises a methane gas cylinder, an air inlet valve, a gas booster, a gas air compressor, a gas mass flow meter, a gas flow regulating valve, a first control valve, a second control valve, and a pressure relief valve; the methane gas cylinder is provided with an air inlet valve connected to the gas booster through the first control valve, the gas booster is connected to the gas air compressor through the second control valve, the gas booster is connected to the gas mass flow meter through the gas flow regulating valve, the gas flow regulating valve and the gas mass flow meter are provided with the pressure relief valve therebetween, and the methane gas cylinder is connected to the wellbore through a gas injection pipeline; the gas booster, the gas air compressor, and the gas mass flow meter are connected to the whole device control box and the computer.

[0011] Optionally or preferably, the liquid injection system comprises a liquid tank, a control valve, a liquid injection pump, a liquid flow regulating valve, a liquid flow meter, and a check valve; the outlet end of the liquid tank is connected to the liquid inlet end of the liquid injection pump through the control valve; the liquid outlet end of the liquid injection pump is connected to the liquid inlet end of the upper end of the wellbore through the liquid flow regulating valve, the liquid flow meter, and the check valve in sequence on the liquid injection pipeline; the liquid injection pump and the liquid flow meter are connected to the whole device control box and the computer.

[0012] Optionally or preferably, the waste gas and liquid recovery system comprises a liquid recovery tank and a pressure relief valve; the liquid recovery tank is connected to the lower end of the wellbore through the control valve; and the pressure relief valve is arranged between the gas mass flow meter and the gas flow regulating valve.

[0013] Optionally or preferably, the data monitoring and processing system comprises a central processing chip, a computer, a connection line, and a supporting operation software; the system can control the simulated wellbore hydrate plug removal system, control the pump body of the gas injection system and the liquid injection system, store the flow of gas and liquid, and process the data of the resistivity tester and the multiple temperature and pressure sensors distributed in the wellbore in real time.

[0014] An experimental method for simulating radio frequency plug removal of hydrates in a production gas well wellbore, comprising the following steps:

[0015] S1: First, place the prepared cylindrical hydrate plug in the hole baffle in the wellbore; the hydrate plug is prepared according to the working conditions and related data of the production gas well, to ensure that the position is in the center of the visualization window and check that the real-time camera can clearly observe the hydrate plug; display the real-time image to the computer screen through the control system;

[0016] S2: Inject methane gas into the wellbore through the gas injection system to reach the required experimental pressure; then inject a certain amount of water into the wellbore according to the amount of injected methane gas to meet the setting of different gas-liquid ratios, and simulate the hydrate plug removal effect evaluation under different production conditions;

[0017] S3: After ensuring the shielding box is grounded, close the shielding box, and use the handheld electromagnetic leakage energy tester to monitor the wave power density around the system, observe the tester indicator light, and ensure that the data does not exceed 1 W / cm 2 If the test value is higher than the value, stop the experiment immediately and install the electromagnetic wave leakage component; set the temperature at which the hydrate plug is completely decomposed through the full device control box, the circulating refrigerator temperature, and the working power; turn on the circulating refrigerator and set the temperature to 17-22℃, turn on the electromagnetic valve; turn on the radio frequency transmitter and set the working power to 500W; set the maximum temperature at which the hydrate plug is completely decomposed under the experimental pressure condition according to the hydrate phase change chart through the control system, and set the current matching device to automatically adjust the impedance to 50Ω; the full device control box always monitors the reflected power and the temperature near the hydrate plug in the wellbore, and when the temperature exceeds the limit, the radio frequency transmitter is turned off and an alarm is given (the limit is greater than the temperature value of the hydrate phase equilibrium curve), if the reflected power is within the limit, increase the radio frequency power to the working power and continue to work, while monitoring the temperature in the wellbore, when the temperature exceeds the limit, the radio frequency transmitter is turned off and an alarm is given, if the reflected power is within the limit, observe the hydrate plug decomposition through the real-time camera, when the temperature in the wellbore reaches the temperature at which the hydrate plug is completely decomposed, turn off the radio frequency transmitter and the electromagnetic valve, complete a radio frequency plug removal experiment, and when the experiment is normal, observe the hydrate plug decomposition and analyze the resistivity tester imaging inversion chart in real time; after the experiment is completed, store a set of data records of the time length of the hydrate plug completely decomposed under the gas-liquid ratio condition through the real-time camera, and calculate the hydrate decomposition rate;

[0018] S4: After completing a radio frequency plug removal experiment, discharge the gas through the pressure relief valve via the gas mass flow meter, and then recover the liquid in the wellbore to the liquid recovery tank; open the shielding box to allow the wellbore to stand, and after all devices are naturally cooled, repeat the above steps to perform at least three sets of plug removal experiments under the same gas-liquid ratio and different radio frequency powers, and perform plug removal experiments under different gas-liquid ratios and the same radio frequency power.

[0019] Based on the above technical solution, the following technical effects can be achieved:

[0020] The application provides a simulated production gas well wellbore hydrate radio frequency deblocking experimental device and method, hydrate blocking blocks generated by a preparation kettle are placed on a hole baffle, the wellbore is filled with methane gas and water in an equal proportion, and the hydrate blocking blocks are located between upper and lower annular electrode rings and electrode plates; a signal generated by a radio frequency transmitting motor acts on the upper and lower annular electrode rings and the electrode plates through a current matcher, a large number of polar molecules (the hydrate blocking blocks and water) exist in the wellbore, a high-frequency alternating electric field is generated between the two electrodes, and a dipole is formed under the action of the electric field; when the size and direction of the electric field change according to a certain frequency, the dipole generates a flip motion to be consistent with the changing direction of the electric field, friction and collision between hydrate molecules are caused, a large amount of heat is generated, the hydrate blocking blocks in the wellbore are heated efficiently, and the hydrate blocking blocks are decomposed, so that the purpose of hydrate rapid deblocking is achieved; the application can quantitatively analyze hydrate decomposition conditions under different gas-liquid ratios by setting different radio frequency currents, can monitor the hydrate decomposition conditions in real time, and can evaluate the radio frequency deblocking effect of the hydrate blocking blocks in the wellbore. BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 is a schematic diagram of an experimental device of the application; Fig. 1 FIG. 2 is a flow chart of radio frequency deblocking operation of the application;

[0022] FIG. 3 is a schematic diagram of a radio frequency deblocking principle of the application. Fig. 2

[0023] FIG. 4 is a schematic diagram of a radio frequency deblocking principle of the application. Fig. 3

[0024] In the figure, 1 is a liquid tank, 2 is a control valve, 3 is a liquid injection pump, 4 is a first control valve, 5 is a methane gas cylinder, 6 is an air inlet valve, 7 is a gas booster, 8 is a second control valve, 9 is a gas flow regulating valve, 10 is a gas air compressor, 11 is a pressure relief valve, 12 is a gas mass flow meter, 13 is a liquid recovery tank, 14 is a control valve, 15 is a shielding box, 16 is a circulating refrigerator, 17 is a water-cooled circulating pipeline, 18 is a safety valve, 19 is a radio frequency transmitting motor, 20 is an electromagnetic valve, 21 is a current matcher, 22 is a liquid flow regulating valve, 23 is a liquid flow meter, 24 is a coaxial cable, 25 is a whole device control box, 26 is a computer, 27 is a real-time camera, 28 is an annular electrode ring and an electrode plate, 29 is a sealing flange, 30 is a pressure probe, 31 is a temperature probe, 32 is a visual window, 34 is a hydrate blocking block, 35 is a retractable aluminum alloy frame, 36 is a hole baffle, 39 is a one-way valve, 40 is a gas injection pipeline, 41 is a liquid injection pipeline, 44 is a wellbore, and 45 is a resistivity tester. EMBODIMENT

[0025] It should be understood that the specific embodiments described herein are merely illustrative of the application and do not limit the application.

[0026] ​​In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by the upper, lower, front, rear, left, right and the like, is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0027] In the description of the present application, unless otherwise explicitly defined, the words such as setting, mounting, connecting and the like should be understood broadly, and the person skilled in the art can determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor are within the protection scope of the present application.

[0029] As Figs. 1-3 For example, a simulated production gas well wellbore hydrate radio frequency plugging removal experimental device, comprising a radio frequency generating system, a simulated wellbore hydrate plugging removal system, a gas injection system, a liquid injection system, a waste gas and liquid recovery system, a data monitoring and processing system; the radio frequency generating system, the simulated wellbore hydrate plugging removal system, the gas injection system, the liquid injection system are connected with the data monitoring and processing system respectively, realizing data monitoring and storage of the radio frequency generating system, the simulated wellbore hydrate plugging removal system, the gas injection system, the liquid injection system, the radio frequency generating system outputs radio frequency to the simulated wellbore hydrate plugging removal system and heats.

[0030] According to one embodiment of the present application, the radio frequency generating system comprises a radio frequency transmitting motor 19, a circulating refrigerator 16, a water-cooled circulating pipeline 17, a current matcher 21, a coaxial cable 24, a ring electrode ring and an electrode plate 28; one end of the radio frequency generating motor 19 is connected with the circulating refrigerator 16 through the water-cooled circulating pipeline 17; the other end of the radio frequency transmitting motor 19 is connected with the current matcher 21, the current matcher 21 is connected with the ring electrode ring and the electrode plate 28 through the coaxial cable 24, and the water-cooled circulating pipeline 17 is provided with an electromagnetic valve 20 and a safety valve 18; the circulating refrigerator 16, the radio frequency transmitting motor 19 and the current matcher 21 are all connected with a whole device control box 25 and a computer 26, the circulating refrigerator 16 is used for consuming a large amount of heat generated by the radio frequency transmitting motor 19 in operation, so as to ensure that the radio frequency transmitting motor 19 always works at a safe temperature, the electromagnetic valve 20 is arranged on the water-cooled circulating pipeline 17, so as to prevent the cooling water from causing dew condensation of components and elements under high temperature, thereby preventing the cooling water from directly flowing back without passing through the radio frequency transmitting motor 19; the function of the current matcher 21 is to automatically match the load impedance according to the decomposition of the hydrate blockage block 34 in the wellbore 33, so that the impedance between the two electrode plates of the wellbore 44 is matched with the output impedance of the radio frequency generator 19, the output power of the radio frequency generating motor 19 can be fully absorbed by the load, so as to improve the efficiency and stability of the radio frequency transmission.

[0031] According to one embodiment of the present application, the radio frequency transmitting motor 19 is a transistor type radio frequency transmitting motor, the radio frequency transmitting motor 19 comprises a signal source, a power divider, a driving module, a power amplifier module, a synthesizer, an input power source of which is three-phase 380V, each module is powered after rectification and filtering, the signal source generates an excitation signal under the control of a controller, the excitation signal is distributed to the driving module and transmitted to the power amplifier module through the power divider, each power amplifier module amplifies the signal by a driver, the amplified signal is pushed to the amplifier after distribution, and then reaches the set power after filtering and synthesizing, finally, the radio frequency output is realized through a directional coupler.

[0032] According to one embodiment of the present application, the simulated wellbore hydrate plug removal system comprises a wellbore 44 with a visualizing window 32, a hydrate plug 34, a retractable alloy frame 35 with built-in resistance probes, a perforated baffle 36 for placing the hydrate plug 34, a temperature probe 31, a pressure probe 30, a resistivity tester 45, a sealing flange 29, a real-time camera 27, and a shielding box 25. The wellbore 44 is provided with annular electrode rings and electrode plates 28 at both ends. An alternating electric field is formed between the two electrode plates in the presence of hydrates and gas-containing water environment, thereby heating the hydrate plug 34. The wellbore 44 is provided with a visualizing window 32, which facilitates the real-time recording of the hydrate decomposition process and the required duration of decomposition by the real-time camera 27. The hydrate plug 34 is a standard cylindrical hydrate. The hydrate plug 34 is placed in the retractable alloy frame 35 at both ends and is placed as a whole on the perforated baffle 36. The retractable alloy frame 35 is provided with probes of the resistivity tester 45 at both ends to monitor the hydrate content of the hydrate plug 34 as a whole and locally in real time. The temperature probe 31 and the pressure probe 30 are optical fiber temperature sensor probes and optical fiber pressure sensor probes, respectively. The temperature probe 31 is arranged near the sealing flange 29 in the wellbore 44 and on the upper side of the hydrate plug 34 to measure the required temperature and pressure conditions for the decomposition of the hydrate plug 34 at different positions. The hydrate plug removal effect can be evaluated by recording the decomposition duration and calculating the hydrate decomposition rate. The shielding box 15 is made of stainless steel to prevent electromagnetic waves from radiating to the surrounding and damaging other instruments in the laboratory. An additional thermal insulation layer is provided on the outside to ensure that the hydrate plug 34 does not decompose naturally. The real-time camera 27 is directed at the hydrate plug 34. The retractable alloy frame 35 is connected to the resistivity tester 45. The temperature probe 31 and the pressure probe 30 are connected to temperature sensors and pressure sensors, respectively. The shielding box 15 is connected to the current matcher 21 through a coaxial cable 24 and is sealed and protected by a copper foil ring. The shielding box 15 is grounded. The temperature sensors, the pressure sensors, the resistivity tester 45, and the real-time camera 27 are connected to the device control box 25 and the computer 26.

[0033] According to one embodiment of the present application, the gas injection system comprises a methane gas cylinder 5, an inlet valve 6, a gas booster 7, a gas air compressor 10, a gas mass flow meter 12, a gas flow regulating valve 9, a first control valve 4, a second control valve 8, and a pressure relief valve 11. The methane gas cylinder 5 is connected to the gas booster 7 through the first control valve 4 and the inlet valve 6, the gas booster 7 is connected to the gas air compressor 10 through the second control valve 8, the gas booster 7 is connected to the gas mass flow meter 12 through the gas flow regulating valve 9, and the pressure relief valve 11 is arranged between the gas flow regulating valve 9 and the gas mass flow meter 12. The compressed gas from the gas booster 7 enters the wellbore 44 from the upper end of the wellbore 44 through the gas flow regulating valve 9 and the gas mass flow meter 12 in sequence, and the methane gas cylinder 5 is connected to the wellbore 44 through the gas injection pipeline 40. The gas booster 7, the gas air compressor 10, and the gas mass flow meter 12 are connected to the device control box 25 and the computer 26. The methane gas cylinder 5 is used to provide natural gas required in the early stage of the experiment, the wellbore 44 can reach the required pressure after being filled with methane gas, and the high natural gas content working condition in the production gas well can be simulated. The gas booster 7 compresses the gas in the methane gas cylinder 5 for the second time, and the compressed air from the gas booster 7 provides power for pumping the methane gas. The gas flow regulating valve 9 is used to change the natural gas content in the wellbore 44, and the effect of radio frequency heating and plugging removal under different natural gas content conditions is analyzed. The gas mass flow meter 12 records the natural gas flow in each experiment in real time, so as to calculate the hydrate decomposition speed under the condition in the experiment. The pressure relief valve 11 is a vent valve, which can release the pressure in the wellbore 44 after the experiment is completed.

[0034] According to one embodiment of the present application, the liquid injection system comprises a liquid tank 1, a control valve 2, a liquid injection pump 3, a liquid flow regulating valve 22, a liquid flow meter 23, and a one-way valve 39. The liquid tank 1 is used to fill the wellbore 44 with liquid in the experimental stage, different gas-liquid ratio conditions are set in the wellbore 44 according to the gas injection amount, and the outlet end of the liquid tank 1 is connected to the liquid inlet end of the liquid injection pump 3 through the control valve 2. The liquid outlet end of the liquid injection pump 3 is connected to the liquid inlet end of the upper end of the wellbore 44 through the liquid flow regulating valve 22, the liquid flow meter 23, and the one-way valve 39 on the liquid injection pipeline 41 in sequence. The liquid flow regulating valve 22 is used to adjust the outlet flow size of the liquid outlet end of the liquid injection pump 3, the liquid flow meter 23 is used to measure the liquid flow injected into the wellbore 44, and the one-way valve 39 prevents the backflow of the fluid in the wellbore 44. The liquid injection pump 3 and the liquid flow meter 23 are connected to the device control box 25 and the computer 26.

[0035] According to one embodiment of the present application, the waste gas and liquid recovery system comprises a liquid recovery tank 13 and a pressure relief valve 11. The liquid recovery tank 13 is connected to the lower end of the wellbore 44 through the control valve 14. The pressure relief valve 11 is arranged between the gas mass flow meter 12 and the gas flow regulating valve 9.

[0036] According to one embodiment of the present application, the data monitoring and processing system includes a central processing chip, a computer 26, a connecting line and a supporting operation software, which can control the simulation of the hydrate plug removal system in the wellbore, control the pump body of the gas injection system and the liquid injection system, store the flow of gas and liquid, process the data of the multiple temperature and pressure sensors distributed in the resistivity tester 45 and the wellbore 44 in real time, and specifically, the data monitoring and processing system controls the radio frequency transmitting motor 19, the circulating refrigerator 16, the current matcher 21, the annular electrode ring and the electrode plate 28, controls the pump body of the gas injection system and the liquid injection system, stores the flow of gas and liquid, processes the data of the multiple temperature and pressure sensors distributed in the resistivity tester 45 and the wellbore 44 in real time, and forms a complete radio frequency plug removal processing system.

[0037] The experimental method for simulating the radio frequency plug removal of the hydrate in the wellbore of the production gas well in the embodiment includes the following steps:

[0038] S1: First, place the prepared cylindrical hydrate plug 34 on the hole baffle 36 in the wellbore 44, the hydrate plug 34 is prepared according to the working condition of the production gas well and related data, ensure that the position is in the center of the visualization window 32 and check that the real-time camera 27 can clearly observe the hydrate plug 34, and display the real-time image to the computer 26 screen through the control system;

[0039] S2: Inject methane gas into the wellbore 44 through the gas injection system to reach the required pressure; then inject a certain amount of water into the wellbore 44 according to the amount of injected methane gas to meet the setting of different gas-liquid ratios, simulate the hydrate plug removal effect evaluation of the wellbore 44 under different production conditions;

[0040] S3: After ensuring that the shielding box 15 is grounded, close the shielding box 15, hold the electromagnetic leakage energy tester, and turn around the shielding box 15 and the surrounding system to monitor the wave power density around the system, observe the tester indicator light and ensure that the data does not exceed 1 W / cm 2If the test value is higher than the value, stop the experiment immediately and install the leakage electromagnetic wave component; set the temperature at which the hydrate plug 34 is completely decomposed, the circulating refrigerator 16 temperature and the working power through the whole device control box 25; open the circulating refrigerator 16, set the temperature to 17-22℃, open the electromagnetic valve 20; then open the radio frequency transmitting motor 19, set the working power to 500W; set the maximum temperature at which the hydrate plug 34 is completely decomposed under the experimental pressure condition according to the hydrate phase change chart through the control system, and set the current matching device 21 to automatically adjust the impedance to 50Ω; the whole device control box 25 always monitors the reflected power and the temperature near the hydrate plug 34 in the wellbore 44, when the temperature exceeds the limited value, the radio frequency transmitting motor 19 is turned off and an alarm is given (the limited value is greater than the temperature value of the hydrate phase equilibrium curve), if the reflected power is within the limit, the radio frequency power is increased to the working power and continues to work, while the temperature in the wellbore 44 is monitored, when the temperature exceeds the limited value, the radio frequency transmitting motor 19 is turned off and an alarm is given, if the reflected power is within the limit, the hydrate plug 34 decomposition condition is observed through the real-time camera 27, when the temperature in the wellbore 44 reaches the temperature at which the hydrate plug 34 is completely decomposed, the radio frequency transmitting motor 19 and the electromagnetic valve 20 are turned off, and a radio frequency plug removal experiment is completed, when the experiment is normally carried out, the hydrate plug 34 decomposition condition is observed in time and the resistivity tester 45 imaging inversion chart is analyzed; after the experiment is completed, a group of gas-liquid ratio conditions of the hydrate plug 34 complete decomposition time is stored through the real-time camera 27, and the hydrate decomposition rate is calculated;

[0041] S4: after completing a radio frequency plug removal experiment, the gas is discharged through the pressure relief valve 11 through the gas mass flow meter 12, and then the liquid in the wellbore 44 is recovered to the liquid recovery tank 13; the wellbore 44 is placed in the shielding box 15, and after all the devices are naturally cooled, the above steps are cycled, and at least three groups of plug removal experiments under the same gas-liquid ratio and different radio frequency powers are carried out, and plug removal experiments under different gas-liquid ratios and the same radio frequency power are carried out.

[0042] The simulated production gas well wellbore hydrate radio frequency plug removal experiment device and method provided by the application can quantitatively analyze the hydrate decomposition condition under different gas-liquid ratio conditions by setting different radio frequency currents, can monitor the hydrate decomposition condition in real time, and can evaluate the radio frequency plug removal effect of the wellbore hydrate plug block.

[0043] The application has been described in detail above in combination with the drawings and examples, but the application is not limited to the above examples, and various changes can be made within the scope of ordinary skills possessed by those skilled in the art without departing from the purpose of the application. Therefore, the application is not limited to the specific examples disclosed herein, and all examples falling within the scope of the claims of the present application belong to the scope of protection of the application.

Claims

1. A radio frequency unblocking experimental device for simulating gas well hydrate blockage, characterized in that, The system includes a radio frequency (RF) generation system, a simulated wellbore hydrate blockage and unblocking system, a gas injection system, a liquid injection system, a waste gas and waste liquid recovery system, and a data monitoring and processing system. The RF generation system, simulated wellbore hydrate blockage and unblocking system, gas injection system, and liquid injection system are each connected to the data monitoring and processing system to monitor and store data from these systems. The RF generation system outputs radio frequency signals to the simulated wellbore hydrate blockage and unblocking system and provides heating. The radio frequency generation system includes a radio frequency transmitting motor (19), a circulating chiller (16), a water-cooled circulating pipeline (17), a current matching device (21), a coaxial cable (24), an annular electrode ring, and an electrode plate (28). One end of the radio frequency transmitting motor (19) is connected to the circulating chiller (16) through the water-cooled circulating pipeline (17). The other end of the radio frequency transmitting motor (19) is connected to the current matching device (21). The current matching device (21) is connected to the annular electrode ring and the electrode plate (28) through the coaxial cable (24). A solenoid valve (20) and a safety valve (18) are installed on the water-cooled circulating pipeline (17). The circulating chiller (16), the radio frequency transmitting motor (19), and the current matching device (21) are all connected to the overall device control box (25) and the computer (26). The simulated wellbore hydrate blockage unblocking system includes a wellbore (44) with a visualization window (32), a hydrate blockage block (34), a retractable alloy frame (35) with a built-in resistance probe, a perforated baffle (36) for placing the hydrate blockage block (34), a temperature probe (31), a pressure probe (30), a resistivity meter (45), a sealing flange (29), a real-time camera (27), and a shielding enclosure (15). The wellbore (44) has annular electrode rings and electrode plates (28) at both ends, and a visualization window (32) on it. The hydrate blockage block (34) is a standard cylindrical hydrate, placed inside the retractable alloy frame (35) at both ends, and entirely placed on the perforated baffle (36). The probes of the resistivity meter (45) are distributed at both ends of the retractable alloy frame (35). The temperature probe (31)... The pressure probes (30) are fiber optic temperature sensor probes and fiber optic pressure sensor probes, respectively. The temperature probes (31) are respectively set near the sealing flange (29) inside the well barrel (44) and on the upper side of the hydrate block (34). The shielding box (15) is made of stainless steel and has an additional heat insulation layer on the outside. The real-time camera (27) is facing the hydrate block (34). The retractable alloy frame (35) is connected to the resistivity tester (45). The temperature probes (31) and pressure probes (30) are respectively connected to the temperature sensor and the pressure sensor. The shielding box (15) is connected to the current matching device (21) through the coaxial cable (24) and is sealed with copper foil. The shielding box (15) is grounded. The temperature sensor, pressure sensor, resistivity tester (45), and real-time camera (27) are connected to the whole device control box (25) and computer (26). The gas injection system includes a methane cylinder (5), an inlet valve (6), a gas booster (7), a gas air compressor (10), a gas mass flow meter (12), a gas flow regulating valve (9), a first control valve (4), a second control valve (8), and a pressure relief valve (11). The methane cylinder (5) is equipped with an inlet valve (6) which is connected to the gas booster (7) via the first control valve (4). The gas booster (7) is connected to the gas air compressor (10) via the second control valve (8). 0) Connection: The gas booster (7) is connected to the gas mass flow meter (12) through the gas flow regulating valve (9). A pressure relief valve (11) is set between the gas flow regulating valve (9) and the gas mass flow meter (12). The methane cylinder (5) is connected to the well shaft (44) through the gas injection pipeline (40). The gas booster (7), the gas air compressor (10), and the gas mass flow meter (12) are all connected to the whole device control box (25) and the computer (26). The injection system includes a liquid tank (1), a control valve (2), a liquid injection pump (3), a liquid flow regulating valve (22), a liquid flow meter (23), and a check valve (39); the outlet end of the liquid tank (1) is connected to the inlet end of the liquid injection pump (3) through the control valve (2); the outlet end of the liquid injection pump (3) is connected to the inlet end of the wellbore (44) in sequence through the liquid flow regulating valve (22), the liquid flow meter (23), and the check valve (39) on the injection pipeline (41); the liquid injection pump (3) and the liquid flow meter (23) are connected to the control box (25) and the computer (26) of the whole device.

2. The experimental device for simulating radio frequency unblocking of hydrated wellbore in a gas well as described in claim 1, characterized in that, The radio frequency transmitting motor (19) is a transistor-type radio frequency transmitting motor, which includes a signal source, a power divider, a drive module, a power amplifier module, and a synthesizer.

3. The experimental device for simulating radio frequency unblocking of hydrated wellbore in a gas well according to claim 1, characterized in that, The waste gas and waste liquid recovery system includes a liquid recovery tank (13) and a pressure relief valve (11). The liquid recovery tank (13) is connected to the lower end of the well shaft (44) through a control valve (14). The pressure relief valve (11) is located between the gas mass flow meter (12) and the gas flow regulating valve (9).

4. The experimental device for simulating radio frequency unblocking of hydrated wellbore in a gas well as described in claim 1, characterized in that, The data monitoring and processing system includes a central processing chip, a computer (26), connecting lines and supporting operating software. It can control the simulated wellbore hydrate blockage and unblocking system, control and store the gas and liquid flow rates of the gas injection system and liquid injection system pumps, and process the resistivity tester (45) and multiple temperature and pressure sensor data distributed in the wellbore (44) in real time.

5. An experimental method for simulating radiofrequency unblocking of hydrated wellbore in a gas production well, implemented based on the experimental apparatus for simulating radiofrequency unblocking of hydrated wellbore in a gas production well as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: First, place the prepared cylindrical hydrate plug (34) onto the perforated baffle (36) in the wellbore (44). The hydrate plug (34) is prepared based on the working conditions and related data of the gas production well. Ensure that the position of the hydrate plug (34) is in the center of the visualization window (32) and check that the real-time camera (27) can clearly observe the hydrate plug (34). Display the real-time image on the computer (26) screen through the control system. S2: First, methane gas is injected into the wellbore (44) through the gas injection system to reach the pressure required for the experiment; then, a certain amount of water is injected into the wellbore (44) according to the amount of methane gas injected, so as to meet the different gas-liquid ratio settings and simulate the evaluation of the hydrate unblocking effect of the wellbore (44) under different production conditions. S3: After ensuring the shielding box (15) is grounded, close the shielding box (15). Hold the electromagnetic leakage energy tester and circle the shielding box (15) and the surrounding system to monitor the wave power density around the system. Observe the indicator light of the tester and ensure that the data does not exceed the electromagnetic radiation safety limit. If the test value is higher than the electromagnetic radiation safety limit, stop the experiment immediately and install the anti-leakage electromagnetic wave component. Set the temperature, temperature and working power of the circulating refrigerator (16) for the complete decomposition of the hydrate block (34) through the full device control box (25). Turn on the circulating refrigerator (16) and set the temperature to 17~22℃. Open the solenoid valve (20). Then turn on the radio frequency transmitter motor (19) and set the working power to 500W. According to the hydrate phase change chart, set the maximum temperature for the complete decomposition of the hydrate block (34) under the experimental pressure condition through the control system. Set the current matching device (21) to automatically adjust the impedance to 50Ω. The full device control box (25) continuously monitors the reflection. The power and temperature near the hydrate block (34) in the wellbore (44) are monitored. When the temperature exceeds the limit, the radio frequency transmitter motor (19) is turned off and an alarm is triggered. If the reflected power is within the limit, the radio frequency power is increased to the working power and continues to work. At the same time, the temperature in the wellbore (44) is monitored. When the temperature exceeds the limit, the radio frequency transmitter motor (19) is turned off and an alarm is triggered. If the reflected power is within the limit, the decomposition of the hydrate block (34) is observed through the real-time camera (27). When the temperature in the wellbore (44) reaches the point where the hydrate block (34) is completely decomposed, the radio frequency transmitter motor (19) and the solenoid valve (20) are turned off to complete one radio frequency unblocking experiment. When the experiment is proceeding normally, the decomposition of the hydrate block (34) needs to be observed in real time and the resistivity tester (45) imaging inversion diagram needs to be analyzed. After the experiment, the data stored by the real-time camera (27) is recorded to record the time for the complete decomposition of the hydrate block (34) under a gas-liquid ratio condition, and the hydrate decomposition rate is calculated. S4: After completing one radio frequency unblocking experiment, first discharge the gas through the gas mass flow meter (12) and the pressure relief valve (11), and then recover the liquid in the well barrel (44) to the liquid recovery tank (13); open the shielding box (15) and let the well barrel (44) stand still. After all the devices have cooled down naturally, repeat the above steps and carry out at least three sets of unblocking experiments with the same gas-liquid ratio and different radio frequency power, and carry out unblocking experiments with different gas-liquid ratios and the same radio frequency power.

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