CN107290224B - Microwave heating device for true triaxial hydraulic fracturing simulation experiment and experiment method - Google Patents

Abstract

The invention discloses a microwave heating device and an experimental method for a true triaxial hydraulic fracturing simulation experiment, wherein the microwave heating device comprises a triaxial pressurizing unit, a microwave heating unit, a fracturing fluid injection unit, an acoustic emission monitoring unit, a temperature monitoring unit and a control and signal acquisition unit: the invention combines the microwave heating equipment and the hydraulic fracturing equipment, avoids the change of the property of the experimental test block caused by the lack of simulated ground stress in the connection process in the existing experimental equipment, and better simulates the influence of the expansion and contraction property of the rock on the hydraulic fracturing effect; the condition that the test block is subjected to thermal expansion in the microwave heating process under the simulated ground stress condition can be monitored; the influence rule of parameters such as the ground stress condition, the heating temperature, the temperature difference between the test block and the fracturing fluid, the perforation condition and the like on the initiation and extension of the crack can be inspected.

Description

Microwave heating device and experimental method for true triaxial hydraulic fracturing simulation experiment

technical field

The present invention relates to the field of oil and gas reservoir hydraulic fracturing and microwave heating research, in particular to a microwave heating device and experimental method for a true triaxial hydraulic fracturing simulation experiment, which is used to monitor the properties of thermal expansion and contraction of rocks under simulated ground stress conditions To improve the effect of hydraulic fracturing, and investigate the influence of parameters such as ground stress conditions, heating temperature, temperature difference between test block and fracturing fluid, and perforation conditions on fracture initiation and extension.

Background technique

With the rapid development of the economy, the country's energy demand continues to increase. Hydraulic fracturing technology is a commonly used stimulation measure in the process of oil and gas reservoir exploitation. The use of hydraulic fracturing technology can increase the natural fractures of oil and gas reservoirs, form artificial fractures, enhance the connectivity between fractures, and improve the permeability of oil and gas reservoirs. At the same time, utilizing the thermal expansion and contraction properties of rocks can improve the efficiency of hydraulic fracturing and facilitate the formation of fracture networks.

Compared with traditional heating technologies such as conduction and convection, microwave heating technology has the characteristics of instantaneous heating, small heat loss and convenient operation. The microwave heating process is a process in which the inside and outside of the heating medium are heated and heated at the same time. Therefore, there is no temperature gradient in the heating process, which greatly improves the heating quality and heating efficiency of the medium. At the same time, its feature of starting and stopping is conducive to the production of automatic control.

In previous studies, the effect of in-situ stress was not considered in the process of heating oil and gas reservoirs, and the experimental results were often different from the heating conditions in real formations. At the same time, the existing devices fail to link the heating of oil and gas reservoirs with the process of hydraulic fracturing, and cannot effectively simulate the effects of thermal expansion and contraction on hydraulic fracturing of underground oil and gas reservoirs. Therefore, designing an experimental device that can combine heating of oil and gas reservoirs with hydraulic fracturing is of great significance for simulating the thermal expansion of underground oil and gas reservoirs and the effects of thermal expansion and contraction of rocks during fracturing.

Therefore, it is first necessary to investigate the in-situ stress conditions, fracture initiation and extension of the oil and gas reservoir burial area in the production area. At the same time, considering the harmfulness of microwave leakage, microwave leakage detection must be carried out in the area where the microwave device is controlled before the experimental device is used, with the standard of "no more than 5 milliwatts per square centimeter".

Contents of the invention

The purpose of the present invention is to monitor the effect of thermal expansion and contraction of rock on improving the effect of hydraulic fracturing under simulated ground stress conditions, and to observe the influence of parameters such as different temperatures, temperature differences and perforation conditions on fracture initiation and extension. This provides a microwave heating device and an experimental method for a true triaxial hydraulic fracturing simulation experiment.

The microwave heating device for the true triaxial hydraulic fracturing simulation experiment of the present invention includes a triaxial pressurization unit, a microwave heating unit, a fracturing fluid injection unit, an acoustic emission monitoring unit, a temperature monitoring unit, and a control and signal acquisition unit:

The three-axis pressurization unit includes four fixed shafts, eight bolts, a fracturing chamber host, a propulsion platform, three loading plates, a rear baffle, an X-direction three-way valve, a Y-direction three-way valve, and a Z-direction three-way valve. Through valve, X-direction pressure sensor, Y-direction pressure sensor, Z-direction pressure sensor, X-direction pressurization hydraulic cylinder, Y-direction pressurization hydraulic cylinder, Z-direction pressurization hydraulic cylinder, two X-direction discharge hydraulic cylinders and hydraulic station ;

Among them, the Y-direction pressurized hydraulic cylinder and the Z-directed pressurized hydraulic cylinder are fixed on the main machine of the fracturing chamber through countersunk screws; the X-directed pressurized hydraulic cylinder and the main machine of the fracturing room are threaded through four fixed shafts and eight bolts. Sealed connection; the propulsion platform is connected by glue, one side is connected to the base of the X-direction pressurized hydraulic cylinder, and the other side is connected to the main machine of the fracturing chamber, and coincides with the bottom edge of the sample chamber, so as to push the experimental test block into the sample chamber; The X-direction material return cylinder is fixed on the main machine of the fracturing chamber through the countersunk head screw; the ends of the hydraulic rods of the X-direction pressurization hydraulic cylinder, Y-direction pressurization hydraulic cylinder, and Z-direction pressurization hydraulic cylinder are respectively connected to the loading plate. It is connected by countersunk screws; in the X direction, there is a rear baffle in the sample chamber, and it is connected with the ends of the hydraulic rods of the two X-direction unloading hydraulic cylinders through countersunk screws;

The X-direction pressurized hydraulic cylinder, Y-directed pressurized hydraulic cylinder and Z-directed pressurized hydraulic cylinder oil inlet connections are divided into two lines with X-direction three-way valve, Y-direction three-way valve and Z-direction three-way valve respectively. , one way is respectively connected with the X-direction pressure sensor, Y-direction pressure sensor and Z-direction pressure sensor through thread sealing, and the pressure information is transmitted to the control and signal acquisition unit; the other one is respectively connected with the hydraulic oil transportation pipeline, and the connection method is hexagonal joint thread Connection; the X-direction return hydraulic cylinder is connected with the hydraulic oil transportation pipeline, and the connection method is a hexagonal joint threaded connection;

The hydraulic station includes a hydraulic valve combination, a pump device, an oil tank, a pressure controller and a bladder accumulator, which are connected to the hydraulic oil transportation pipeline to provide a hydraulic source, and the connection method is a hexagonal joint threaded connection;

The microwave heating unit includes a microwave generating device, a waveguide and a microwave antenna; the microwave generating device can adjust the frequency and power of the microwave within a certain range; the microwave antenna is fixed in the base of the triaxial pressurizing unit device, The microwave antenna is located below the fracturing sample chamber; the waveguide is connected to the microwave antenna, and the waveguide is fixed in the base of the triaxial pressurization unit device;

The fracturing fluid injection unit includes a one-way hydraulic cylinder, a fracturing fluid pumping control system and a fracturing fluid pipeline, which can control the pressure and speed of the fracturing fluid pumping; the fracturing fluid pipeline passes through the front hexagon bolt and The rear hexagonal bolt, the front hexagonal bolt and the simulated casing fixed on the experimental test block are connected through thread sealing, and the rear hexagonal bolt is connected with the host machine of the fracturing chamber through thread sealing to prevent microwave leakage;

The acoustic emission monitoring unit includes an acoustic emission sensor connected to the four vertices of the loading plate by gluing, the transmission line of the acoustic emission sensor protrudes from the notch behind the loading plate, and the transmission line of the acoustic emission sensor is fixed in the fixed pipeline; in Y, In the Z direction, one end of the fixed pipe is threadedly connected to the main unit of the fracturing chamber, and the other end can be used to fix the transmission line; the material of the fixed pipe is a microwave reflective material;

The temperature monitoring unit includes a temperature sensor connected to the center of the loading plate through glue, and the temperature sensor transmission line protrudes from the notch behind the loading plate and is fixed in the fixed pipe;

The control and signal acquisition unit is connected with the pressure sensor transmission line, and the simulated ground stress value is collected and displayed on the display device; the control and signal acquisition unit is connected with the hydraulic station through the signal transmission line, and the three-axis pressurization control device can be used to directly control the applied pressure. The magnitude of the triaxial stress; the control and signal acquisition unit is connected with the transmission line of the acoustic emission sensor, and the built-in acoustic emission signal processing device processes the acoustic emission signal and displays it on the display device; the control and signal acquisition unit and the fracturing fluid injection unit pass through the signal transmission line Connect, collect the fracturing fluid pumping information and display it on the display device; the control and signal acquisition unit is connected with the temperature sensor transmission line, monitor the real-time information of the heating of the experimental test block and display it on the display device;

Preferably, except for the material at the bottom of the sample chamber directly above the microwave antenna, the other materials of the fracturing chamber host are all microwave reflective materials; The cylinders and hydraulic rods of the pressurizing hydraulic cylinder, the pressurizing hydraulic cylinder in the Z direction, and the two unloading hydraulic cylinders in the X direction are microwave reflective materials; the acoustic emission sensor and temperature sensor are resistant to high temperature, and the coupling agent used is resistant to high temperature, which is convenient Sensitively detected signal.

The experimental method of the microwave heating device of the true three-axis hydraulic fracturing simulation experiment of the present invention comprises the following steps:

Step 1. Calculate the microwave frequency λ: measure the dielectric constant ε' and dielectric loss factor ε" of the collected oil and gas reservoir rock samples, and calculate the microwave frequency λ based on the size of the test block, where L is the experimental test Distance between the bottom surface of the block and the microwave antenna:

Step 2. Make the experimental test block: Drill the reaming section and the open hole fracturing section at the center of the collected oil and gas reservoir rock samples, insert the simulated casing, and take it as the center, pour concrete to make a size of 200* 200*200mm experimental test block;

Step 3: Put the experimental test block in place: inject water into the simulated casing on the prepared experimental test block to drain the air, and connect it to the fracturing fluid pipeline; smear on the surface of the acoustic emission sensor in the X, Y, and Z directions High-temperature-resistant couplant to better measure the acoustic emission signal, and use the X-direction pressurized hydraulic cylinder to push the experimental test block into the sample chamber of the fracturing chamber host, and at the same time connect the rear hexagonal bolt to the fracturing chamber host;

Step 4. Triaxial pressure loading: start the control and signal acquisition unit, and use the triaxial pressure control device to control the triaxial pressure loading until the set simulated ground stress value is reached;

Step 5, microwave heating: turn on the microwave generating device, heat the experimental test block with the microwave frequency λ calculated in step 1, and observe the acoustic emission signal waveform collected by the acoustic emission monitoring unit; when the temperature on the display device reaches the set temperature, Turn off the microwave generator;

Step 6. Carry out hydraulic fracturing: turn on the fracturing fluid pump system, pump fracturing fluid to the experimental test block with a certain displacement according to the set pumping pressure or pumping speed; collect data during the fracturing process through the acoustic emission monitoring unit Acoustic emission signal, observe the waveform change of the acoustic emission signal; observe the hydraulic fracturing pressure curve and the X, Y, Z triaxial pressure curve on the display device; when the hydraulic fracturing pressure value and the triaxial pressure value return to zero, the hydraulic fracturing pressure end of cracking process;

Step 7. Take out the experimental test block: Use the three-axis pressurization control device to control the pressure in the X, Y, and Z directions to gradually decrease until it returns to zero. The cylinder and the rear baffle push out the test block;

Beneficial effects of the present invention:

Compared with the prior art, the microwave heating device and the experimental method of the true triaxial hydraulic fracturing simulation experiment provided by the present invention combine the microwave heating equipment and the hydraulic fracturing equipment, avoiding the existing experimental equipment, due to the The change of the properties of the experimental test block caused by the lack of simulated in-situ stress can better simulate the influence of rock thermal expansion and contraction on the effect of hydraulic fracturing; it can monitor the impact of the experimental test block when microwave heating is performed under the simulated in-situ stress condition. The situation of thermal expansion; it can investigate the influence of parameters such as ground stress conditions, heating temperature, temperature difference between test block and fracturing fluid, and perforation conditions on fracture initiation and extension.

Description of drawings

Fig. 1 is the schematic structural diagram of the simulation experiment device of the present invention.

Fig. 2 is a three-dimensional structure schematic diagram of the triaxial pressing unit of the present invention.

Fig. 3 is a structural sectional view of the triaxial pressing unit of the present invention.

Fig. 4 is a schematic diagram of the half-section structure of the loading plate of the present invention.

Fig. 5 is a schematic diagram of the transmission structure of the acoustic emission sensor and the temperature sensor of the present invention.

Fig. 6 is a schematic diagram of the structure of the experimental test block in the present invention.

In the figure: 1. Microwave generator; 2. Waveguide; 3. Microwave antenna; 4. Hydraulic station; 5. Oil tank; 6. Bladder accumulator; 7. Hydraulic valve combination; 8. Pump device; 9. Pressure Controller; 10. X-direction pressurized hydraulic cylinder; 11. Y-directed pressurized hydraulic cylinder; 12. Z-directed pressurized hydraulic cylinder; 13. X-directed material return hydraulic cylinder; 14. Bolts; 15. Fixed shaft; 16. 17. Fracturing chamber host; 18. Sample chamber; 9. X-direction pressure sensor; 20. Y-direction pressure sensor; 21. Z-direction pressure sensor; 22. X-direction three-way valve; 23. Y-direction three-way valve; One-way valve; 24. Z-direction three-way valve; 25. Loading plate; 26. Fracturing fluid pipeline; 27. Front hexagonal bolt; 28. Rear hexagonal bolt; 29. Hydraulic oil transportation pipeline; 30. Fracturing fluid pumping control System; 31. One-way hydraulic cylinder; 32. Signal transmission line; 33. Fixed pipeline; 34. Acoustic emission sensor transmission line; 35. Temperature sensor transmission line; 36. Pressure sensor transmission line; 37. Display device; 38. Three-axis pressurization control Device; 39. Acoustic emission signal processing device; 301. Back baffle; 401. Acoustic emission sensor; 402. Temperature sensor; 403. Notch; 601. Experimental test block; ; 604. Mock casing.

Detailed ways

As shown in Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5, a microwave heating device for a true triaxial hydraulic fracturing simulation experiment according to the present invention includes a triaxial pressurizing unit, a microwave heating unit, a pressing Fissure fluid injection unit, acoustic emission monitoring unit, temperature monitoring unit and control and signal acquisition unit:

The three-axis pressurization unit includes four fixed shafts 15, eight bolts 14, a fracturing chamber host 17, a propulsion table 16, three loading plates 25, a rear baffle 301, an X-direction three-way valve 22, and a Y-direction three-way valve. One-way valve 23, Z-direction three-way valve 24, X-direction pressure sensor 19, Y-direction pressure sensor 20, Z-direction pressure sensor 21, X-direction pressurization hydraulic cylinder 10, Y-direction pressurization hydraulic cylinder 11, Z-direction pressurization hydraulic cylinder Cylinder 12, two X-direction unloading hydraulic cylinders 13 and hydraulic station 4;

Among them, the Y-direction pressurized hydraulic cylinder 11 and the Z-directed pressurized hydraulic cylinder 12 are fixed on the main machine 17 of the fracturing chamber through countersunk screws; It is threaded and sealed with eight bolts 14; the propulsion platform 16 is connected with the base of the X-direction pressurized hydraulic cylinder 10 on one side, and connected to the main machine 17 of the fracturing chamber on the other side, and coincides with the bottom edge of the sample chamber 18 , so as to push the experimental test block into the sample chamber 18; the X-direction material return cylinder 13 is fixed on the fracturing chamber main machine 17 through countersunk screws; the X-direction pressurization hydraulic cylinder 10, the Y-direction pressurization hydraulic cylinder 11, the Z-direction pressurization The ends of the hydraulic rods of the pressure hydraulic cylinder 12 are respectively connected with the loading plate 25 by countersunk screws; in the X direction, a rear baffle 301 is placed in the sample chamber, and it is connected with two X direction unloading hydraulic cylinders 13 The end of the hydraulic rod is connected by a countersunk screw;

X-direction pressurized hydraulic cylinder 10, Y-directed pressurized hydraulic cylinder 11 and Z-directed pressurized hydraulic cylinder 12 are connected to the oil inlet ports of X-directed three-way valve 22, Y-directed three-way valve 23 and Z-directed three-way valve respectively. 24 The thread connection is divided into two ways, one way is respectively connected with the X-direction pressure sensor 19, the Y-direction pressure sensor 20 and the Z-direction pressure sensor 21 through thread sealing, and the pressure information is transmitted to the control and signal acquisition unit; the other way is respectively connected with the hydraulic oil transportation The pipeline 29 is connected, and the connection method is a hexagonal joint threaded connection; the X-direction material return hydraulic cylinder 13 is connected to the hydraulic oil transportation pipeline 29, and the connection method is a hexagonal joint threaded connection;

The hydraulic station 4 includes a hydraulic valve combination 7, a pump device 8, a fuel tank 5, a pressure controller 9 and a bladder accumulator 6, and is connected to a hydraulic oil transportation pipeline 29 to provide a hydraulic source, and the connection method is a hexagonal joint threaded connection;

The microwave heating unit includes a microwave generator 1, a waveguide 2 and a microwave antenna 3; the microwave generator 1 can adjust the frequency and power of microwaves within a certain range; the microwave antenna 3 is fixed on the triaxial pressurization unit In the base, the microwave antenna 3 is located below the fracturing sample chamber; the waveguide 2 is connected to the microwave antenna 3, and the waveguide 2 is fixed in the base of the triaxial pressurization unit;

The fracturing fluid injection unit includes a one-way hydraulic cylinder 31, a fracturing fluid pumping control system 30 and a fracturing fluid pipeline 26, which can control the pressure and speed of fracturing fluid pumping; the fracturing fluid pipeline 26 passes through The front hexagonal bolt 27 and the rear hexagonal bolt 28, the front hexagonal bolt 27 and the simulated sleeve 604 fixed on the experimental test block 601 are connected by thread sealing, and the rear hexagonal bolt 28 is connected with the host machine 17 of the fracturing chamber by thread sealing to prevent microwave leakage ;

The acoustic emission monitoring unit includes an acoustic emission sensor 401 connected to the four apexes of the loading plate by gluing, the acoustic emission sensor transmission line 34 protrudes from the notch 403 behind the loading plate 25, and the acoustic emission sensor transmission line 34 is fixed on a fixed In the pipeline 33; in the Y and Z directions, one end of the fixed pipeline 33 is threadedly connected to the fracturing chamber host 17, and the other end of the fixed pipeline 33 can fix the transmission line; the material of the fixed pipeline 33 is a microwave reflective material;

The temperature monitoring unit includes a temperature sensor 402 connected to the center of the loading plate by gluing, and the temperature sensor transmission line 35 protrudes from the notch 403 behind the loading plate 25 and is fixed in the fixed pipe 33;

The control and signal acquisition unit is connected with the pressure sensor transmission line 36, collects the simulated ground stress value and displays it on the display device 37; the control and signal acquisition unit is connected with the hydraulic station 4 through the signal transmission line 32, and uses its three-axis pressurization control device 38 can directly control the magnitude of the applied triaxial stress; the control and signal acquisition unit is connected to the acoustic emission sensor transmission line 34, and the built-in acoustic emission signal processing device 39 processes the acoustic emission signal and displays it on the display device 37; the control and signal acquisition unit is connected to the acoustic emission sensor transmission line 34. The fracturing fluid injection unit is connected through the signal transmission line 32, collects the fracturing fluid pumping information and displays it on the display device 37; the control and signal acquisition unit is connected with the temperature sensor transmission line 35, monitors the real-time information of the heating of the experimental test block and displays it on the display device 37 on;

Preferably, except for the bottom material of the sample chamber 18 directly above the microwave antenna 3, the main machine 17 of the fracturing chamber is made of microwave reflective materials; The cylinder bodies and hydraulic rods of the pressurizing hydraulic cylinder 10, the Y-direction pressurizing hydraulic cylinder 11, the Z-direction pressurizing hydraulic cylinder 12, and the two X-direction unloading hydraulic cylinders 13 are microwave reflective materials; the acoustic emission sensor 401 and temperature The sensor 402 is resistant to high temperature, and the couplant used is resistant to high temperature, so it is convenient and sensitive to measure the signal.

The experimental method of the microwave heating device of the true three-axis hydraulic fracturing simulation experiment of the present invention comprises the following steps:

Step 1. Calculate the microwave frequency λ: measure the dielectric constant ε' and dielectric loss factor ε" of the collected oil and gas reservoir rock samples, and calculate the microwave frequency λ based on the size of the test block, where L is the experimental test Distance between the bottom surface of the block and the microwave antenna:

Step 2. Make the test block: Drill the reaming section 602 and the open hole fracturing section 603 at the center of the collected oil and gas reservoir rock sample, insert the simulated casing 604, and pour concrete to obtain the size An experimental test block 601 of 200*200*200mm;

Step 3: Put the experimental test block in place: inject water into the simulated casing 604 on the prepared experimental test block 601 to drain the air, and connect it to the fracturing fluid pipeline 26; the acoustic emission sensors in the X, Y, and Z directions Apply high-temperature-resistant couplant on the 401 surface to better measure the acoustic emission signal, and use the X-direction pressurized hydraulic cylinder 10 to push the experimental test block into the sample chamber 18, and at the same time connect the rear hexagonal bolt 28 to the main machine of the fracturing chamber 17 connections;

Step 4. Triaxial pressure loading: start the control and signal acquisition unit, and use the triaxial pressure control device 38 to control the triaxial pressure loading until the set simulated ground stress value is reached;

Step 5, microwave heating: turn on the microwave generating device 1, heat the experimental test piece with the microwave frequency λ calculated in step 1, observe the acoustic emission signal waveform collected by the acoustic emission monitoring unit; when the temperature on the display device 37 reaches the set temperature , turn off the microwave generator 1;

Step 6. Perform hydraulic fracturing: turn on the fracturing fluid pump system 30, pump fracturing fluid to the experimental test block with a certain displacement according to the set pumping pressure or pumping speed; collect the fracturing process through the acoustic emission monitoring unit Acoustic emission signal in, observe the waveform change of acoustic emission signal; Observe the hydraulic fracturing pressure curve and the X, Y, Z triaxial pressure curve on the display device 37; When the hydraulic fracturing pressure value and the triaxial pressure value return to zero, The hydraulic fracturing process ends;

Step 7. Take out the experimental test block: Use the triaxial pressurization control device 38 to control the pressure in the X, Y, and Z directions to gradually decrease until it returns to zero. The unloading hydraulic cylinder 13 and the tailgate 301 push out the experimental test block 601.

Claims (3)

1. A microwave heating device for a true triaxial hydraulic fracturing simulation experiment, characterized in that it includes a triaxial pressurization unit, a microwave heating unit, a fracturing fluid injection unit, an acoustic emission monitoring unit, a temperature monitoring unit, and control and signal Acquisition unit: The triaxial pressurization unit includes four fixed shafts (15), eight bolts (14), a fracturing chamber host (17), a propulsion table (16), three loading plates (25), a rear baffle (301 ), X-direction three-way valve (22), Y-direction three-way valve (23), Z-direction three-way valve (24), X-direction pressure sensor (19), Y-direction pressure sensor (20), Z-direction pressure sensor ( 21), X-direction pressurization hydraulic cylinder (10), Y-direction pressurization hydraulic cylinder (11), Z-direction pressurization hydraulic cylinder (12), two X-direction unloading hydraulic cylinders (13) and hydraulic station (4) ; Y-direction pressurized hydraulic cylinder (11) and Z-directed pressurized hydraulic cylinder (12) are all fixed on the fracturing chamber host (17) by countersunk screws; X-directed pressurized hydraulic cylinder (10) is connected to the fracturing chamber host ( 17) Through four fixed shafts (15) and eight bolts (14) for thread sealing connection; the propulsion table (16) is connected by glue joint, one side is connected to the base of the X-direction pressurized hydraulic cylinder (10), and the other side is connected to the The host machine (17) of the fracturing chamber is connected and coincides with the bottom edge of the sample chamber (18), so as to push the test piece into the sample chamber (18); On the split chamber host machine (17); the hydraulic rod ends of the X-direction pressurization hydraulic cylinder (10), the Y-direction pressurization hydraulic cylinder (11), and the Z-direction pressurization hydraulic cylinder (12) are respectively connected with the loading plate (25) , the connection mode is a countersunk screw connection; in the X direction, a rear baffle (301) is placed in the sample chamber, and it is connected with the ends of the hydraulic rods of the two X-direction unloading hydraulic cylinders (13) through countersunk screws; X-direction pressurized hydraulic cylinder (10), Y-directed pressurized hydraulic cylinder (11), and Z-directed pressurized hydraulic cylinder (12) are connected to the oil inlet ports of the X-direction three-way valve (22) and Y-direction three-way valve respectively. The valve (23) and the Z-direction three-way valve (24) are threadedly connected into two paths, and one path is respectively connected to the X-direction pressure sensor (19), the Y-direction pressure sensor (20) and the Z-direction pressure sensor (21) through threaded sealing. The pressure information is transmitted to the control and signal acquisition unit; the other road is respectively connected to the hydraulic oil transportation pipeline (29), and the connection method is a hexagonal joint threaded connection; the X-direction unloading hydraulic cylinder (13) is connected to the hydraulic oil transportation pipeline (29) , the connection method is hexagonal joint threaded connection; The hydraulic station (4) includes a hydraulic valve combination (7), a pump device (8), an oil tank (5), a pressure controller (9) and a bladder accumulator (6), and is connected with a hydraulic oil transportation pipeline (29) to Provide a hydraulic source, and the connection method is a hexagonal joint threaded connection; The microwave heating unit includes a microwave generating device (1), a waveguide (2) and a microwave antenna (3); the microwave antenna (3) is fixed in the base of the triaxial pressurization unit, and the microwave antenna (3) is located The bottom of the sample chamber; the waveguide (2) is connected with the microwave antenna (3), and the waveguide (2) is fixed in the base of the triaxial pressurization unit; The fracturing fluid injection unit includes a one-way hydraulic cylinder (31), a fracturing fluid pumping control system (30) and a fracturing fluid pipeline (26), which can control the pressure and speed of the fracturing fluid pumping; The cracking liquid pipeline (26) passes through the front hexagonal bolt (27) and the rear hexagonal bolt (28), and the front hexagonal bolt (27) is connected with the simulated casing (604) fixed on the experimental test block (601) by thread sealing, The rear hex bolt (28) is connected to the fracturing chamber host (17) through a threaded seal; The acoustic emission monitoring unit includes an acoustic emission sensor (401) connected to the four vertices of the loading plate by gluing, and the acoustic emission sensor transmission line (34) protrudes from the notch (403) behind the loading plate (25), The acoustic emission sensor transmission line (34) is fixed in the fixed pipe (33); in the Y and Z directions, one end of the fixed pipe (33) is threadedly connected to the fracturing chamber host (17), and the other end of the fixed pipe (33) can be fixed Transmission line; The temperature monitoring unit includes a temperature sensor (402) connected to the center of the loading plate by glue, and the temperature sensor transmission line (35) protrudes from the notch (403) behind the loading plate (25) and is fixed in the fixed pipe ( 33) in; The control and signal acquisition unit is connected with the pressure sensor transmission line (36), and the simulated ground stress value is collected and displayed on the display device (37); the control and signal acquisition unit is connected with the hydraulic station (4) through the signal transmission line (32), The applied triaxial stress can be directly controlled by using its triaxial pressure control device (38); the control and signal acquisition unit is connected with the acoustic emission sensor transmission line (34), and the built-in acoustic emission signal processing device (39) processes the acoustic emission signal And displayed on the display device (37); the control and signal acquisition unit is connected with the fracturing fluid injection unit through the signal transmission line (32), and the fracturing fluid pumping information is collected and displayed on the display device (37); the control and signal acquisition The unit is connected with the temperature sensor transmission line (35), monitors the real-time information of the heating of the experimental test block and displays it on the display device (37). 2. A microwave heating device for a true triaxial hydraulic fracturing simulation experiment according to claim 1, characterized in that: the loading plate (25), the rear baffle (301), the rear hexagonal bolt (28) , fixed pipeline (33), X-direction pressurization hydraulic cylinder (10), Y-direction pressurization hydraulic cylinder (11), Z-direction pressurization hydraulic cylinder (12), two cylinders of X-direction discharge hydraulic cylinder (13) Body and hydraulic rod are microwave reflective materials. 3. an experimental method of the microwave heating device of the true triaxial hydraulic fracturing simulation experiment described in claim 1, comprising the steps: Step 1. Calculate the microwave frequency λ: measure the dielectric constant ε' and dielectric loss factor ε" of the collected oil and gas reservoir rock samples, and calculate the microwave frequency λ based on the size of the test block, where L is the experimental test Distance between the bottom surface of the block and the microwave antenna:

Step 2. Making the experimental test block: Drill the reaming section (602) and the open hole fracturing section (603) at the center of the collected oil and gas reservoir rock sample, and insert the simulated casing (604), and take it as the center , pouring concrete to make an experimental test block (601) whose size is 200*200*200mm; Step 3, put the experimental test block in place: inject water into the simulated casing (604) on the prepared experimental test block (601) to discharge the air, and connect it to the fracturing fluid pipeline (26); Apply high-temperature-resistant couplant on the surface of the acoustic emission sensor (401) in the direction to better measure the acoustic emission signal, and use the X-direction pressurized hydraulic cylinder (10) to push the experimental test block into the sample chamber (18) , and connect the rear hex bolt (28) with the fracturing chamber host (17) at the same time; Step 4, triaxial pressure loading: start the control and signal acquisition unit, and use the triaxial pressure control device (38) to control the triaxial pressure loading until the set simulated ground stress value is reached; Step 5, microwave heating: open the microwave generating device (1), heat the experimental test block with the microwave frequency λ calculated in step 1, observe the acoustic emission signal waveform collected by the acoustic emission monitoring unit; when the temperature on the display device (37) When the set temperature is reached, the microwave generating device (1) is turned off; Step 6. Perform hydraulic fracturing: the fracturing fluid pumping control system (30) pumps fracturing fluid to the experimental test block with a certain displacement according to the set pumping pressure or pumping speed; Acoustic emission signal during the fracturing process, observe the waveform change of the acoustic emission signal; observe the hydraulic fracturing pressure curve and the X, Y, Z triaxial pressure curve on the display device (37); when the hydraulic fracturing pressure value and the triaxial pressure When the value returns to zero, the hydraulic fracturing process ends; Step 7. Take out the experimental test block: use the three-axis pressurization control device (38) to control the pressure in the X, Y, and Z directions to gradually decrease until it returns to zero, and the hydraulic rod of the X-direction pressurization hydraulic cylinder (10) moves out of the sample chamber ( 18), control the X-direction unloading hydraulic cylinder (13) and tailgate (301) to push out the experimental test block (601).

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