DTS fracturing injection flow distribution monitoring device and method based on DAS interpretation

Abstract

The invention relates to the technical field of hydraulic fracturing, in particular to a DTS fracturing injection flow distribution monitoring device and method based on DAS interpretation. The device comprises a simulated rock core, a simulated wellbore, a distributed optical fiber, a triaxial pressurization plate, a heating plate, a heat insulation plate, an intermediate container, a high-pressure constant-flux pump, a fracturing fluid injection pump, a fracturing fluid tank, a hydraulic oil tank, a three-way hydraulic pump, a distributed optical fiber demodulation instrument, a true triaxial simulated fracturing rock core rack and a computer. According to the DTS fracturing injection flow distribution monitoring method based on DAS explanation, the hydraulic fracturing process under the reservoir temperature field condition can be simulated in the laboratory environment, real-time monitoring of injection flow distribution in the hydraulic fracturing process is achieved, real-time adjustment of fracturing injection parameters is facilitated, reference is provided for on-site fracturing design, and the method has the advantages of being high in practicability and the like. In addition, on the basis of the established relational expression of the flow and the temperature, distributed monitoring of the flow of each section can be achieved only through the DTS.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and natural gas production enhancement and modification, and in particular relates to a DTS fracturing injection flow distribution monitoring device and method based on DAS interpretation. Background Art

[0002] In recent years, with the gradual reduction of conventional oil and gas resources and the increasing difficulty of exploitation, unconventional oil and gas resources have gradually come into people's view. Faced with the complex geological engineering problems in the process of unconventional oil and gas resource exploitation, hydraulic fracturing technology has become one of the core technical means to increase oil and gas field production.

[0003] Distributed fiber optic monitoring technology can realize real-time monitoring of the distribution of fracturing injection profiles and the expansion of hydraulic fractures during the operation, and thus make real-time adjustments to the fracturing operation parameters. After the fracturing operation is completed, distributed fiber optics can also be used to monitor the fluid production profile, understand the production status of each fracturing layer, and conduct post-fracturing effect evaluation.

[0004] Currently, hydraulic fracturing experimental equipment utilizing distributed fiber optic monitoring utilizes only one of the following technologies: distributed fiber optic temperature sensing or distributed fiber optic acoustic sensing. There is a lack of experimental equipment that can monitor both together. Furthermore, the distributed fiber optic temperature monitoring systems currently used in indoor hydraulic fracturing simulation experiments can only qualitatively monitor flow using temperature, but cannot quantitatively interpret flow. The monitoring results are inaccurate. Regarding fiber optic laying methods, some employ "adjacent well" laying, while others employ spiral laying around the wellbore. There is a lack of a method that more closely aligns with the conditions at the fracturing construction site, where the fiber is laid closely along the wellbore. From a field application perspective, achieving quantitative distribution of injected and produced fluids throughout the entire fracturing production process requires the use of different distributed fiber optic sensing technologies and quantitative interpretation at different stages, which is cumbersome and costly. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides the following technical solutions:

[0006] In the first aspect, the present invention provides a DTS fracturing injection flow distribution monitoring device based on DAS interpretation, characterized in that the device includes a large-size true triaxial confining pressure module for placing test specimens and providing a simulated downhole pressure environment for the test specimens; a temperature control module for providing a simulated formation temperature environment; a hydraulic fracturing module for pressurized water injection into the test specimens; a distributed optical fiber temperature and acoustic wave signal acquisition module for collecting core temperature and acoustic wave signals during the fracturing process, and interpreting the temperature and acoustic wave signals to obtain temperature distribution information and injection flow distribution information along the simulated wellbore.

[0007] Preferably, the large-scale true triaxial confining pressure module comprises a true triaxial simulated fracturing core rack (21), a triaxial pressure plate (4), an X-direction hydraulic pump (13), a Y-direction hydraulic pump (14), a Z-direction hydraulic pump (15), a hydraulic oil tank (16), and a computer (12); the triaxial pressure plate (4) is used to apply simulated triaxial ground stress to the simulated core (1) placed on the true triaxial simulated fracturing core rack (21); and the triaxial pressure plate (4) is connected to three independent hydraulic pumps via piston rods.

[0008] Preferably, the temperature control module comprises a heating plate (5), a heat insulating plate (6), a temperature controller (19), and a computer (20); the heating plate (5) is distributed on the outer surface of the simulated core (1); the heat insulating plate (6) is arranged outside the heating plate (5); and the temperature controller (19) is used to control the heating temperature of the simulated core (1).

[0009] Preferably, the hydraulic fracturing module comprises a simulated wellbore (2), an intermediate container (7), a fracturing fluid injection pump (9), a fracturing fluid tank (10), a high-pressure horizontal flow pump (8), a hydraulic oil tank (11), and a computer (12), and is used to simulate the fracturing injection process.

[0010] Preferably, the distributed optical fiber temperature and acoustic wave signal acquisition module comprises a DTS optical fiber (3), a DAS optical fiber (22), a distributed optical fiber temperature demodulation instrument (18), a distributed optical fiber acoustic wave demodulation instrument (23) and a computer (17), and is used for receiving and interpreting monitoring data.

[0011] Preferably, the distributed optical fiber (3) and the distributed optical fiber (22) are arranged outside the simulated wellbore (2).

[0012] On the other hand, the present invention provides a DTS fracturing injection flow rate distribution monitoring experimental method based on DAS interpretation, which is performed by any of the above-mentioned DTS fracturing injection flow rate distribution monitoring devices based on DAS interpretation, comprising the following steps:

[0013] Step 1: Preparation of test piece

[0014] According to the experimental design, a simulated wellbore (2) is processed, and distributed optical fibers (3) and distributed optical fibers (22) are tightly laid outside the simulated wellbore (2). The simulated core (1) is made of cement, gravel and additives, and a certain amount of water is added to prepare concrete, which is poured into a mold. During the pouring process, initial cracks are prefabricated inside the simulated core (1) according to the designed perforation position. The simulated wellbore (2) after laying the optical fibers is placed in the center of the core casting mold, and the top of the simulated wellbore (2) is exposed to the artificial specimen. After the specimen is completed, the simulated wellbore exposed to the specimen is connected to the pumping pipeline through a threaded connection, and the specimen is placed in a true triaxial simulated fracturing core rack (21), and a triaxial pressure plate (4), a heating plate (5) and a heat insulation plate (6) are installed;

[0015] Step 2: Set the simulation reservoir parameters

[0016] Start the hydraulic pumps in the X, Y, and Z directions, set the simulated ground stress in the horizontal, vertical, and vertical directions on the computer (12), and apply confining pressure to the specimen by synchronous loading in accordance with the experimental design and the ground stress difference of the target block. The pressure in each direction can be controlled separately. After the simulated ground stress loading is completed, set the temperature of the heating plate (5) according to the temperature of the reservoir;

[0017] Step 3: Conduct hydraulic fracturing physical simulation experiments

[0018] The high-pressure horizontal flow pump (8) and the fracturing fluid injection pump (9) are started to pump the fracturing fluid into the intermediate container (7). The high-pressure horizontal flow pump (8) is controlled by a computer (12) to inject the fracturing fluid into the simulated wellbore (2) according to the set pump pressure and displacement. At the same time, the distributed optical fiber temperature demodulation instrument (18) and the distributed optical fiber acoustic wave demodulation instrument (23) are started to collect the optical fiber temperature and acoustic wave sensor signals and transmit them to the computer (17) after demodulation. The computer (17) records the temperature change along the wellbore and the acoustic wave energy change at the perforation position along the wellbore during the fracturing process.

[0019] Step 4: Complete the experiment and unload the specimen

[0020] When the pump pressure and time curve displayed on the computer (12) stabilizes at a certain pressure value over time, the fracturing fluid injection pump (9) and the high-pressure horizontal flow pump (8) are turned off. After the pump pressure gradually decreases to a stable value, the distributed optical fiber temperature demodulation instrument (18), the distributed optical fiber acoustic wave demodulation instrument (23) and the computer (17) are turned off, and the acquisition and demodulation of the optical fiber temperature and acoustic wave sensor signals are stopped. Then, the computer (20) is used to stop the continued heating of the simulated core (1) through the temperature controller (19), and the three-way hydraulic pressure is unloaded to zero to restore the system to its initial state.

[0021] On the other hand, the present invention provides a DTS fracturing injection flow distribution monitoring method based on DAS interpretation, which is performed by the DTS fracturing injection flow distribution monitoring device based on DAS interpretation according to any one of the above claims, comprising the following steps:

[0022] Step 1: Demodulate to obtain the sound wave energy and temperature distribution curve

[0023] The distributed optical fiber acoustic wave demodulation instrument (23) is used to demodulate and obtain an acoustic wave energy distribution curve, wherein the acoustic wave energy is the horizontal coordinate and the monitoring depth is the vertical coordinate; the distributed optical fiber temperature demodulation instrument (18) is used to demodulate and obtain a temperature distribution curve along the wellbore during the simulated fracturing experiment, wherein the temperature is the horizontal coordinate and the monitoring depth is the vertical coordinate;

[0024] Step 2: Correct the perforation position and read the acoustic energy and temperature change values

[0025] Compare the temperature distribution curve with the acoustic energy distribution curve to correct the perforation position, and read the peak acoustic energy E at different perforation positions after correction. n , read the temperature change value △T at different perforation positions after correction;

[0026] Step 3: Calculate the flow distribution at different perforation locations

[0027] By reading the peak acoustic energy at different perforation locations, the flow rate distribution at different perforation locations is calculated using a flow interpretation model based on high-frequency acoustic energy.

[0028] Step 4: Regression analysis to establish the relationship between temperature and flow

[0029] The temperature change value △T at different perforation positions after correction and the calculated flow rate value q at different perforation positions were recorded. The above experimental process was repeated to obtain multiple sets of temperature and flow rate data. Finally, regression analysis was performed to establish the relationship between temperature and flow rate, realizing the quantitative interpretation of flow rate demodulated by distributed optical fiber temperature sensing.

[0030] Preferably, the traffic interpretation model is:

[0031]

[0032] N1q1(t)+…+N n q n (t) = q T (t) (2)

[0033]

[0034] Where, E is the acoustic energy FBE in a certain perforation cluster i, dB; n is the total number of perforation clusters, q iis the flow rate at a certain perforation position, m 3 / s;q T is the total flow rate of injected fluid, m 3 / s; t is the monitoring time, s; N is the number of perforations per cluster; A is an empirical constant, which is taken as 0.09.

[0035] Preferably, the method further comprises step five:

[0036] The experiment was conducted again, and the corresponding flow rate value q was calculated by using the established relationship through the temperature change value △T at different perforation positions. The calculated flow rate values ​​at different perforation positions were added together and compared with the total injection volume of the experiment to verify the accuracy of the calculation results.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The DTS fracturing injection flow distribution monitoring device proposed in this invention, based on DAS interpretation, can simulate real reservoir temperature and pressure under indoor conditions by combining a temperature control device with a large-scale true triaxial hydraulic fracturing device. At the same time, it utilizes distributed fiber optic temperature and acoustic wave sensing technology to achieve a quantitative interpretation of the fracturing injection flow during hydraulic fracturing based on distributed fiber optic temperature sensing technology. This overcomes the disadvantage that the current distributed fiber optic temperature sensing technology used in indoor testing to monitor hydraulic fracturing can only provide a qualitative interpretation of the injection flow distribution.

[0039] (2) The present invention uses distributed fiber optic temperature sensing technology to monitor the distribution of fracturing injection flow during hydraulic fracturing under reservoir temperature and pressure conditions, explores the influence of perforation parameters, pumping parameters, ground stress, reservoir temperature and other parameters on the injection flow distribution during hydraulic fracturing, and evaluates the hydraulic fracturing effect more realistically and effectively. A large number of experiments can guide actual fracturing production and construction, and provide a reference for the application of distributed fiber optic temperature sensing technology in the integrated monitoring of hydraulic fracturing and liquid production profiles. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural schematic diagram of the fracturing injection flow distribution monitoring device of the present invention.

[0041] Among them: 1. Simulated core, 2. Simulated wellbore, 3. Distributed optical fiber, 4. Triaxial pressure plate, 5. Heating plate, 6. Insulation plate, 7. Intermediate container, 8. High-pressure horizontal flow pump, 9. Fracturing fluid injection pump, 10. Fracturing fluid tank, 11. Hydraulic oil tank, 12. Computer, 13. X-direction hydraulic pump, 14. Y-direction hydraulic pump, 15. Z-direction hydraulic pump, 16. Hydraulic oil tank, 17. Computer, 18. Distributed optical fiber temperature demodulation instrument, 19. Temperature controller, 20. Computer, 21. True triaxial simulated fracturing core rack, 22. Distributed optical fiber, 23. Distributed optical fiber acoustic wave demodulation instrument. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below with reference to the accompanying drawings.

[0043] like Figure 1 As shown, the present invention provides a DTS fracturing injection flow distribution monitoring device based on DAS interpretation. The device mainly includes the following four modules: a large-scale true triaxial confining pressure module, which is used to place test specimens and provide a simulated downhole pressure environment for the test specimens; a temperature control module, which provides a simulated formation temperature environment; a hydraulic fracturing module, which is used to pressurize and inject fracturing fluid into the test specimens; a distributed optical fiber temperature and acoustic wave signal acquisition module, which is used to collect the temperature and acoustic wave distributed optical fiber signals of the core during the fracturing process, and interpret the temperature and acoustic wave signals to obtain the temperature difference before and after injection and the injection flow distribution information.

[0044] The large-scale true triaxial confining pressure module includes a true triaxial simulated fracturing core rack 21 for placing the simulated core 1, a triaxial pressure plate 4 for pressurizing the simulated core 1, an X-direction hydraulic pump 13, a Y-direction hydraulic pump 14, a Z-direction hydraulic pump 15, and a hydraulic oil tank 16 connected to the triaxial pressure plate 4 via piston rods. A computer 12 is connected to the three-way hydraulic pump to control the loading of the three axial pressures. The triaxial loading mode has a constant pressure control mode and can also achieve independent loading of the three axes. The true triaxial simulated fracturing core rack 21 is suitable for cores of 500mm×500mm×500mm cubes (it can also meet the requirements of cores of 400mm×400mm×400mm and 300mm×300mm). It consists of a true triaxial simulated fracturing core rack base, a pressure-bearing shell, a loading pad, a short-stroke loading piston, a center hole injection port, a lifting bracket, etc. (the component dimensions match the overall core dimensions).

[0045] The simulated rock core 1 is made of cement, gravel and additives as raw materials, and is cast with a certain amount of water. Initial cracks are prefabricated inside it, and distributed optical fibers are tightly laid along the wellbore direction on the outside of the pre-perforated simulated wellbore 2. Then, the simulated wellbore 2 is placed in the center of the simulated rock core casting mold to cast the simulated rock core 1, and the top of the simulated wellbore 2 is exposed to the artificial specimen. After the specimen is completed, the simulated wellbore exposed to the specimen is connected to the hydraulic fracturing module through a pumping pipeline. The hydraulic fracturing device provides injection pressure for the simulated wellbore 2. Under the action of the injection pressure, the pre-perforated pressure of the simulated wellbore 2 is transmitted to the simulated rock core 1, and then to the pre-fabricated initial cracks. The injection of low-temperature liquid generates a temperature difference inside the simulated rock core 1. The distributed optical fiber monitors the temperature difference and the acoustic wave signal generated by the fluid flow, thereby monitoring the distribution of the injection flow of the injection fracturing.

[0046] The temperature control module includes a heating plate 5 for heating the core and an insulation plate 6 for isolating the high temperature. The heating plate 5 is close to the surface of the core 1, and the insulation plate 6 is arranged outside the heating plate 5. It also includes a temperature controller 18 and a computer 19 for setting reservoir temperature parameters. One end of the temperature controller 18 is connected to the heating plate 5, and the other end is connected to the computer 19 to control the simulated core heating temperature.

[0047] The heating plate 5 and the heat insulation plate 6 are distributed on the outer surface of the simulated core 1. The triaxial pressure plate 4 squeezes the specimen in the horizontal, vertical and vertical directions. The triaxial pressure plates 4 in different directions are respectively connected to the three-way hydraulic pump through piston rods, and the stress in different directions is loaded using a computer setting.

[0048] The hydraulic fracturing module includes a simulated wellbore 2 with prefabricated perforations, a fracturing fluid injection pump 9 for injection fracturing control, a high-pressure horizontal flow pump 8, and a computer 12 and a hydraulic oil tank 10 connected to the high-pressure horizontal flow pump 8. The fracturing fluid tank 10 provides injection fracturing fluid.

[0049] The distributed optical fiber temperature and acoustic wave signal acquisition module includes a distributed optical fiber 3 and a distributed optical fiber 22 for monitoring the fracturing injection flow along the wellbore direction, wherein the distributed optical fiber 3 and the distributed optical fiber 22 are DTS optical fiber and DAS optical fiber respectively, as well as a distributed optical fiber temperature demodulation instrument 18, a distributed optical fiber acoustic wave demodulation instrument 23 and a computer 17 for receiving, interpreting and imaging optical fiber data.

[0050] In order to better understand the present invention, the following is a detailed description of a method for using the DTS fracturing injection flow distribution monitoring device based on DAS interpretation, including the following steps:

[0051] Step 1: Make the experimental specimen

[0052] According to the experimental design, the simulated wellbore (2) is processed. First, perforations are prepared on the simulated wellbore (2), and soluble plastic sheets are installed at the position of each cluster of perforations. The function of the soluble plastic sheets is to dissolve the soluble plastic sheets as the fluid is injected during the simulated fracturing process, forming initial cracks and making it easier for the fluid to enter. Then, the prepared simulated wellbore (2) is fixed to the center of the mold with a clamp. Cement, gravel and additives are used as raw materials, and a certain amount of water is added to make concrete. The concrete is poured into a 500mm×500mm×500mm cubic mold. At the same time, a simulated wellbore 2 with prefabricated perforations is prepared according to the experimental design, and a plastic sheet is placed outside the simulated wellbore 2. The distributed optical fiber is tightly laid along the direction of the wellbore, and the simulated wellbore 2 with the laid distributed optical fiber and prefabricated perforations is placed in the center of a 500mm×500mm×500mm cubic mold, and then the simulated core 1 is cast. During the casting process, the soluble plastic sheet dissolves to form prefabricated initial cracks to simulate the cracks after artificial perforation, and the top of the simulated wellbore 2 is exposed to the artificial specimen. After the simulated core is air-dried, it is demoulded and placed in a true triaxial simulated fracturing core rack 21, and then the triaxial pressure plate 4, heating plate 5 and insulation plate 6 are installed, and the simulated wellbore 2 exposed to the specimen is connected to the pumping pipeline through threads.

[0053] Step 2: Set the simulation reservoir parameters

[0054] According to the experimental design and the difference in ground stress in the target block, the hydraulic pumps in the X, Y, and Z directions are started, and the simulated ground stress in the horizontal, vertical, and vertical directions is set on the computer 12. The confining pressure is applied to the specimen by synchronous loading to maintain the pressure at a constant level. The pressure in each direction can be controlled separately. After the simulated ground stress loading is completed, the temperature of the heating plate 5 is set on the computer 20 according to the experimental design and the temperature of the reservoir in the target block.

[0055] Step 3: Conduct hydraulic fracturing physical simulation experiments

[0056] Start the fracturing fluid injection pump 9 and the high-pressure horizontal flow pump 8, set the pump pressure and displacement on the computer 12, and then inject liquid into the test piece. The control software collects the pumping pressure conditions during the hydraulic fracturing process in real time. At the same time, the distributed optical fiber temperature demodulation instrument 18 and the distributed optical fiber acoustic wave demodulation instrument 23 are turned on to collect the optical fiber temperature and acoustic wave sensor signals, demodulate them, and transmit them to the computer 17. The computer 17 records the temperature and acoustic wave changes at the perforation positions along the wellbore during the fracturing process, and then interprets the temperature changes and liquid inflow conditions at each perforation position.

[0057] Step 4: Complete the experiment and unload the test specimen

[0058] When the pump pressure and time curve displayed on the computer 12 stabilizes near a certain pressure value over time, it means that fracturing has been completed. At this time, the fracturing fluid injection pump 9 and the high-pressure horizontal flow pump 8 are first turned off. After the pump pressure gradually decreases to a stable value, the distributed optical fiber temperature demodulator 18, the distributed optical fiber acoustic wave demodulator 23 and the computer 17 are turned off, and the acquisition and demodulation of the optical fiber temperature and acoustic wave sensor signals are stopped. Then, the computer 20 is used to stop the continued heating of the simulated core 1 through the temperature controller 19, and the three-way hydraulic pressure is unloaded to zero, the system is restored to the initial state, and the experiment is completed.

[0059] The DTS fracturing injection flow distribution monitoring method based on DAS interpretation includes the following steps:

[0060] Step 1: Demodulate to obtain the sound wave energy and temperature distribution curve

[0061] The distributed optical fiber acoustic wave demodulation instrument 23 demodulates the acoustic wave energy distribution curve, where the abscissa represents the acoustic wave energy and the ordinate represents the monitoring depth. The distributed optical fiber temperature demodulation instrument 22 demodulates the temperature distribution curve during the simulated fracturing experiment, where the abscissa represents the temperature and the ordinate represents the monitoring depth.

[0062] Step 2: Correct the perforation position and read the acoustic energy and temperature change values

[0063] Compare the obtained temperature distribution curve with the acoustic wave energy distribution curve to correct the perforation position, and read the acoustic wave energy peak value E at different perforation positions after correction. n and temperature change △T;

[0064] Step 3: Calculate the flow distribution at different perforation locations

[0065] Based on the read acoustic energy peak, the flow rate distribution at different perforation locations is calculated using a flow interpretation model based on high-frequency acoustic energy. The model is as follows:

[0066]

[0067] N1q1(t)+...+N n q n (t) = q T (t) (2)

[0068]

[0069] Where E is the acoustic energy in a certain perforation cluster i, dB; n is the total number of perforation clusters, q i is the flow rate at a certain perforation position, m 3 / s;q T is the total flow rate of injected fluid, m 3 / s; t is the monitoring time, s; N is the number of perforations per cluster; A is an empirical constant, which is 0.09;

[0070] Step 4: Regression analysis to establish the relationship between temperature and flow

[0071] The temperature change ΔT at different perforation locations after correction and the calculated flow rate q at different perforation locations were recorded. The above experimental process was repeated to obtain multiple sets of temperature and flow rate data. Finally, regression analysis was performed to establish the relationship between temperature and flow rate, realizing the quantitative interpretation of flow rate demodulated by distributed optical fiber temperature sensing.

[0072] Step 5: Formula Verification

[0073] The experiment was conducted again, and the corresponding flow rate value q was calculated by using the established relationship through the temperature change value △T at different perforation positions. The calculated flow rate values ​​at different perforation positions were added together and compared with the total injection volume of the experiment to verify the accuracy of the calculation results.

[0074] The present invention proposes a DTS fracturing injection flow distribution monitoring device and method based on DAS interpretation. A large-scale true triaxial physical simulation device including a temperature control system is developed. Based on the DAS flow interpretation method, a quantitative relationship between the temperature difference monitored by the DTS and the injected fluid is established, enabling quantitative monitoring of the distribution of the fracturing injection flow using distributed fiber optic temperature sensing technology. The device and method provided by the present invention can establish a relationship between temperature and flow using DAS-monitored flow data. Since DTS technology is widely used in the field, the method proposed by the present invention can be used during field construction to quantitatively monitor the distribution of injected and produced fluids throughout the entire fracturing production process using only distributed fiber optic temperature sensing technology, simplifying operations and reducing costs.

[0075] 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 and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A DTS fracturing injection flow distribution monitoring device based on DAS interpretation, characterized in that: The device includes a large-size true triaxial confining pressure module, which is used to place the test specimen and provide a simulated downhole pressure environment for the test specimen; a temperature control module, which is used to provide a simulated formation temperature environment; a hydraulic fracturing module, which is used to pressurize and inject water into the test specimen; and a distributed optical fiber temperature and acoustic wave signal acquisition module, which is used to collect core temperature and acoustic wave signals during the fracturing process, and interpret the temperature and acoustic wave signals to obtain temperature distribution information and injection flow distribution information along the simulated wellbore.

2. The DTS fracturing injection flow distribution monitoring device based on DAS interpretation as described in claim 1, wherein the large-size true triaxial confining pressure module comprises a true triaxial simulated fracturing core rack (21), a triaxial pressure plate (4), an X-direction hydraulic pump (13), a Y-direction hydraulic pump (14), a Z-direction hydraulic pump (15), a hydraulic oil tank (16), and a computer (12). The triaxial pressure plate (4) is used to apply simulated triaxial geostress to the simulated core (1) placed on the true triaxial simulated fracturing core rack (21), and the triaxial pressure plate (4) is connected to three independent hydraulic pumps through a piston rod.

3. According to the DTS fracturing injection flow distribution monitoring device based on DAS interpretation as described in claim 1, the temperature control module includes a heating plate (5), an insulation plate (6), a temperature controller (19), and a computer (20), the heating plate (5) is distributed on the outer surface of the simulated core (1), the insulation plate (6) is arranged outside the heating plate (5), and the temperature controller (19) is used to control the heating temperature of the simulated core (1).

4. The DTS fracturing injection flow distribution monitoring device based on DAS interpretation as described in claim 1, the hydraulic fracturing module includes a simulated wellbore (2), an intermediate container (7), a fracturing fluid injection pump (9), a fracturing fluid tank (10), a high-pressure horizontal flow pump (8), a hydraulic oil tank (11), and a computer (12), which are used to simulate the fracturing injection process.

5. According to the DTS fracturing injection flow distribution monitoring device based on DAS interpretation as described in claim 1, the distributed optical fiber temperature and acoustic wave signal acquisition module includes a DTS optical fiber (3), a DAS optical fiber (22), a distributed optical fiber temperature demodulation instrument (18), a distributed optical fiber acoustic wave demodulation instrument (23) and a computer (17), which is used for receiving and interpreting monitoring data.

6. The DTS fracturing injection flow distribution monitoring device based on DAS interpretation according to claim 1, wherein the distributed optical fiber (3) and the distributed optical fiber (22) are arranged outside the simulated wellbore (2).

7. A DTS fracturing injection flow distribution monitoring experimental method based on DAS interpretation, which is carried out by the DTS fracturing injection flow distribution monitoring device based on DAS interpretation according to any one of claims 1 to 6, comprising the following steps: Step 1: Preparation of test piece Processing and preparing a simulated wellbore (2), preparing perforation holes on the simulated wellbore (2), installing a soluble mold at each cluster of perforation positions to prepare initial fractures, closely laying distributed optical fibers (3) and distributed optical fibers (22) outside the simulated wellbore (2), and then fixing the prepared simulated wellbore (2) at the center of the mold with a clamp, pouring concrete material into the mold to cast the simulated core (1); after the test piece is made, connecting the simulated wellbore (2) exposed in the test piece to a pumping pipeline, placing the test piece in a true triaxial simulated fracturing core rack (21), and installing a triaxial pressure plate (4), a heating plate (5) and a heat insulation plate (6); Step 2: Set simulation reservoir parameters Starting the hydraulic pump to apply confining pressure to the test piece to simulate ground stress, and after the simulated ground stress loading is completed, setting the temperature of the heating plate (5) according to the temperature of the reservoir; Step 3: Conduct hydraulic fracturing physical simulation experiments The fracturing fluid is injected into the simulated wellbore (2) according to the set pump pressure and displacement, and the monitored optical fiber temperature and acoustic wave sensor signals are collected to obtain the temperature changes along the wellbore during the fracturing process and the acoustic wave energy changes at the perforation positions along the wellbore.

8. A DTS fracturing injection flow distribution monitoring method based on DAS interpretation, which is performed by the DTS fracturing injection flow distribution monitoring device based on DAS interpretation according to any one of claims 1 to 6, comprising the following steps: Step 1: Demodulate to obtain the sound wave energy and temperature distribution curve The distributed optical fiber acoustic wave demodulation instrument (23) is used to demodulate the acoustic wave energy distribution curve, and the distributed optical fiber temperature demodulation instrument (18) is used to demodulate the temperature distribution curve along the wellbore during the simulated fracturing experiment; Step 2: Correct the perforation position and read the acoustic energy and temperature change values Compare the temperature distribution curve with the acoustic wave energy distribution curve to correct the perforation position, and read the acoustic wave energy peak value E at different perforation positions after correction. n , read the temperature change value △T at different perforation positions after correction; Step 3: Calculate the flow distribution at different perforation locations The flow interpretation model based on high-frequency acoustic energy calculates the flow distribution at different perforation locations; Step 4: Establish the relationship between temperature and flow Using the flow distribution calculated in step three, establish the relationship between temperature change and flow.

9. The DTS fracturing injection flow distribution monitoring method based on DAS interpretation as claimed in claim 8, wherein the flow interpretation model in step 3 is: N1q1(t)+…+N n q n (t)=q T (t) (2) Where E is the acoustic energy in a certain perforation cluster i; n is the total number of perforation clusters; q i is the flow at a certain perforation position; q T is the total flow rate of injected fluid; t is the monitoring time; N is the number of perforations per cluster; A is an empirical constant.

10. The DTS fracturing injection flow rate distribution monitoring method based on DAS interpretation according to claim 8 further comprises the steps of: The experiment was carried out again, and the established relationship was used to calculate the corresponding flow value q through the temperature change value △T at different perforation positions. The calculated flow values ​​at different perforation positions were added together and compared with the total injection volume of the experiment to verify the accuracy of the calculation results.

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