Physical simulation experiment device and method for fine exploration of water outlet layer section of underground rock stratum

Abstract

The invention provides an underground rock stratum water outlet section fine exploration physical simulation experiment device and method.The underground rock stratum water outlet section fine exploration physical simulation experiment device comprises a water storage tank, the water storage tank is connected with a water pump, the water pump is connected with one ends of a plurality of water supply valves through one-way valves, and the other ends of the water supply valves are connected with rock bins in a one-to-one correspondence mode; the rock bins are vertically installed on the side wall of the simulation drilling pipe. Flange end covers are installed at the two ends of the simulation drilling pipe respectively, a water return opening sealing head is installed on the flange end cover at the tail end of the simulation drilling pipe, and the water return opening sealing head is connected with the water storage tank through a water return valve to return water. An energy storage pressure stabilizer is further arranged between the water storage tank and one end of each water supply valve. A sound wave sensing armored optical cable is coaxially installed in the simulation drilling pipe. Various geological and hydrological conditions in an actual underground rock stratum environment can be effectively simulated, the exploration precision of a water-rich layer section is improved by analyzing the change rule of sound wave signals, and reliable technical support is provided for coal mine water disaster prevention and control and safe production.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogeological exploration, relates to the detection of aquifers, and specifically relates to a physical simulation experimental device and method for fine exploration of water-bearing strata sections in underground rock formations. Background Art

[0002] During the coal mining process, the exploration of relatively water-rich strata sections in the aquifers of the coal seam roof and floor (underground rock formations) is crucial for ensuring the safe production of coal mines. However, the existing exploration methods have significant deficiencies in terms of accuracy, efficiency, and cost, and are difficult to cope with the increasingly complex mine environment, especially in key areas such as the Jurassic coalfields in western China. The coal seam roof in this area usually has special geological characteristics such as high porosity, well-developed microfractures, and thick sandstone, which easily lead to water inrush during the mining process, seriously threatening the safe production of the mining area. Traditional hydrogeological exploration methods, such as core logging and pumping tests, although they can provide macroscopic geological parameters, have limitations in accurately exploring relatively water-rich strata sections and are difficult to meet the high-precision requirements of modern mine water prevention and control measures such as water interception and emission reduction projects, thus affecting the safe and efficient mining of mines.

[0003] To solve this problem, in recent years, the development of Distributed Acoustic Sensing (DAS) technology has provided a new solution for the fine exploration of aquifers in underground rock formations. The DAS technology realizes real-time monitoring of continuous acoustic signals over a large range through fiber optic sensors, has advantages such as high spatial resolution, strong real-time performance, and low cost, can accurately capture the tiny acoustic signals caused by groundwater flow and geological structure changes, and thus detect relatively water-rich strata sections in underground rock formations. Compared with traditional exploration methods, the DAS technology has more significant advantages in terms of monitoring range and sensitivity, and is particularly suitable for the exploration of relatively water-rich strata sections and water hazard prevention and control in complex geological environments. It can significantly improve the accuracy of exploring relatively water-rich strata sections of water hazards and the response speed of water hazard prevention and control. At the same time, the DAS technology provides reliable data support for the dynamic management of mine water prevention and control and the intelligent mining of mines in mining areas, helps to optimize mine water prevention and control measures, such as the design of water interception and emission reduction projects, reduces the risk of water inrush in mining areas, and ensures the safety of miners' lives.

[0004] Although the DAS technology shows great potential in the exploration of relatively water-rich strata sections of aquifers, most of the existing research relies on on-site test data, which brings many difficulties in actual operation. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a physical simulation experimental device and method for fine exploration of water-bearing strata sections in underground rock formations, and solve the technical problem that the exploration accuracy of the existing exploration methods for water-rich strata sections needs to be further improved due to relying on on-site test data.

[0006] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0007] A physical simulation experiment device for fine exploration of water-producing intervals in underground rock formations, comprising a water storage water tank, the water storage water tank is connected to a water pump, the water pump is connected to one end of a plurality of water supply valves through a one-way valve, and the other end of each water supply valve is correspondingly connected to a rock chamber, and the plurality of rock chambers are vertically installed on the side wall of a simulation drilling pipe.

[0008] Flange end covers are respectively installed at both ends of the simulation drilling pipe, and a water return port sealing head is installed on the flange end cover at the tail end of the simulation drilling pipe. The water return port sealing head is connected to the water storage water tank through a water return valve for water return.

[0009] The rock chamber includes a hollow rock chamber main body, a rock chamber cap is installed at the top of the rock chamber main body, and the rock chamber cap is communicated with the water supply valve; the bottom end of the rock chamber main body is detachably installed at the top end of a hollow connector, and the bottom end of the connector is connected to the side wall of the simulation drilling pipe. An interchangeable water outlet plate is clamped inside the connector, and a simulation water outlet is provided through the middle of the water outlet plate; the cavity between the water outlet plate, the connector, the rock chamber main body and the rock chamber cap is a lithology simulation cavity.

[0010] An energy storage voltage stabilizer is further provided between the water storage water tank and one end of the plurality of water supply valves.

[0011] An acoustic sensing armored optical cable is coaxially installed inside the simulation drilling pipe, and both ends of the acoustic sensing armored optical cable extend out of the flange end covers at both ends of the simulation drilling pipe.

[0012] A liquid turbine flowmeter and a pressure transmitter are respectively installed on the high-pressure pipelines between each water supply valve and the rock chamber.

[0013] The present invention further has the following technical features:

[0014] The energy storage voltage stabilizer includes a plurality of energy storage devices. The energy storage device includes an energy storage tank, and an energy storage tank inlet valve, an energy storage tank drain valve and an overflow valve are installed in parallel on the energy storage tank. A pressure gauge is provided between the energy storage tank and the overflow valve.

[0015] The energy storage voltage stabilizer further includes a first electromagnetic flow valve and a second electromagnetic flow valve connected in parallel. One end of the first electromagnetic flow valve and one end of the second electromagnetic flow valve are both connected to one end of the plurality of water supply valves; the other end of the first electromagnetic flow valve is connected to the energy storage tank inlet valve of the first group of energy storage devices connected in parallel, and the energy storage tank drain valve and the overflow valve of the first group of energy storage devices connected in parallel are connected to the water storage water tank; the other end of the second electromagnetic flow valve is connected to the energy storage tank inlet valve of the second group of energy storage devices connected in parallel, and the energy storage tank drain valve and the overflow valve of the second group of energy storage devices connected in parallel are connected to the water storage water tank.

[0016] One end of the first electromagnetic flow valve and one end of the second electromagnetic flow valve are both connected to one end of the same water discharge valve, and the other end of the water discharge valve is connected to the water storage tank.

[0017] It further includes a hydrodynamic parameter acquisition system. The hydrodynamic parameter acquisition system includes a computer terminal. The computer terminal is connected to an analog signal acquisition board through a 485-to-USB communication module. The analog signal acquisition board is connected to a 24V power module. The analog signal acquisition board is also respectively connected to a liquid turbine flowmeter and a pressure transmitter to collect signals, and the liquid turbine flowmeter and the pressure transmitter are also connected to the 24V power module to obtain power.

[0018] The water pump adopts a reciprocating piston pump.

[0019] There are three rock chambers, which are respectively placed at positions 12.64 - 12.83m, 18.47 - 18.66m, and 20.54 - 20.73m away from the head end of the simulated drilling pipe.

[0020] The acoustic sensing armored optical cable is connected to the flange end cover through an optical fiber sealing head.

[0021] The acoustic sensing armored optical cable is connected to a distributed acoustic sensing system.

[0022] This embodiment protects a physical simulation experiment method for fine exploration of the water-producing layer section in underground rock strata. The physical simulation experiment method is characterized in that the physical simulation experiment device for fine exploration of the water-producing layer section in underground rock strata as described above is adopted.

[0023] The sandstones filled in the lithology simulation cavity are respectively fine-grained sandstone, medium-grained sandstone, coarse-grained sandstone or conglomerate.

[0024] The shape of the simulated water outlet is circular or square. The inner diameter of the circular simulated water outlet is 3mm, 5mm, 7mm or 9mm.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] (Ⅰ) By simulating the acoustic wave generation and propagation environment under complex conditions such as different flow velocities, lithologies and outlet sizes, and combining with the advanced distributed acoustic sensing technology (DAS), the present invention realizes the accurate identification of relatively water-rich layer sections in a thick aquifer. This technology can effectively simulate various geological and hydrological conditions in the actual underground rock strata environment. By analyzing the variation law of acoustic wave signals, it improves the exploration accuracy of water-rich layer sections, providing reliable technical support for coal mine water disaster prevention and safe production.

[0027] (II) The present invention breaks through the technical bottleneck of traditional hydrogeological exploration methods. Traditional exploration of water-rich strata in coal mine roofs usually relies on methods such as drilling, geophysical exploration, and geological analysis. However, these methods often face problems such as insufficient accuracy, long time consumption, and being greatly affected by the environment, especially under complex groundwater conditions. To address this technical bottleneck, the present invention provides a multi-condition simulation experimental device that simulates the complex hydrodynamic environment of actual underground aquifers by controlling multiple key factors such as flow rate, lithology, and outlet size. This innovation breaks through the limitations of traditional exploration methods and provides a more accurate and flexible exploration means for coal mine water hazard prevention and control.

[0028] (III) The present invention precisely controls the simulation of the water flow and acoustic wave propagation environment. Another innovation of the present invention lies in the precise adjustment function of the hydrodynamic control system, especially the simulation of the dynamic changes of water flow under different flow rates and lithology conditions. The experimental device combines the dynamic environment of acoustic wave propagation and precisely controls multiple parameters such as water pressure, flow rate, and outlet size to simulate the flow regime of underground water in real time. This precise control based on the experimental simulation environment enables the present invention to effectively reproduce the real situation of underground water-rich strata and solves the problem of data deviation caused by unstable experimental conditions in traditional technologies.

[0029] (IV) The present invention conducts hydrodynamic and lithology analysis based on distributed acoustic sensing technology (DAS). The present invention realizes high-precision acquisition and real-time analysis of acoustic signals through distributed acoustic sensing technology (DAS). DAS technology can sense minute vibration changes through optical fibers, so it can accurately capture the effects of water flow changes, lithology differences, and outlet conditions on acoustic wave propagation. This technical means can not only solve the problem of insufficient sensitivity in traditional acoustic detection but also greatly improve the identification accuracy of water-rich strata in coal mine roofs, providing strong data support for flood prevention and control.

[0030] (V) The present invention realizes experimental data and model inversion technology under multi-variable conditions. During the experiment, the present invention combines various variables (such as sandstone particle size, flow rate, outlet size, etc.) to gradually adjust the experimental conditions and inversely derive the hydrodynamic model through the acoustical signals collected in real time. This innovative experimental design enables comprehensive hydrogeological data to be obtained under multiple experimental conditions, thereby further improving the exploration accuracy of water-rich strata. This analysis method based on acoustic signal inversion has strong adaptability and universality and can be applied to the exploration of other types of underground aquifers.

[0031] (Ⅵ) The present invention has an adjustable water outlet design. The simulated water outlet drilling device designed by the present invention can simulate water outlets of different shapes (such as circular, square, rectangular) and different sizes through replaceable water outlets, and can reproduce a variety of different underground water flow environments. Each water outlet shape and size can generate different water flow patterns, which enables the experimental device to conduct simulation experiments in a more diverse hydrographic environment, thereby improving the adaptability of the experiment and the diversity of experimental data. This design breaks through the limitation of the fixed water outlet size in traditional experimental devices and has stronger application scalability.

[0032] (Ⅶ) The present invention can realize an intelligent hydrodynamic and acoustic signal monitoring system. The hydrodynamic control system of the present invention is combined with a distributed acoustic sensing system to form an intelligent monitoring and data analysis platform. Through the data interaction of a high-precision flowmeter, pressure sensor and DAS system, the system can monitor the changes of hydrodynamic parameters in the experiment in real time, and analyze the acoustic signals through a signal processing system to invert the relevant characteristics of underground water flow. This system not only improves the accuracy of data collection, but also realizes automatic data storage and analysis, greatly improving the efficiency and reliability of the experiment.

[0033] (Ⅷ) The present invention has a highly integrated and modular design. The experimental device of the present invention adopts a highly integrated and modular design concept, allowing users to freely combine and adjust each module (such as the rock chamber (4), water outlet, hydrodynamic control system, acoustic sensor, etc.) according to experimental needs, so as to adapt to the exploration needs of different types of groundwater layers. This flexible configuration design makes the device have strong scalability and applicability, and can be widely used in groundwater hydrogeological exploration tasks of different scales and types.

[0034] (Ⅸ) The present invention not only proposes a number of novel design concepts in traditional hydrogeological exploration equipment, but also solves the problems of low exploration accuracy and poor environmental adaptability commonly existing in the prior art through a simulation method of multi-condition experiments and advanced acoustic technology. The present invention has great application potential and market prospects in the fields of coal mine water disaster prevention and control, water resource utilization, hydrogeological exploration, etc., significantly improving the exploration accuracy of the water-rich layer section of the coal mine roof, and providing a reliable technical guarantee for the efficient, safe and sustainable mining of coal mines. Description of the Drawings

[0035] Figure 1 It is a schematic diagram of the overall connection relationship of the simulation device for detecting the water-richness of sandstone aquifers.

[0036] Figure 2 It is a schematic diagram of the structure of the rock chamber.

[0037] Figure 3 It is a schematic diagram of the structure of the energy storage device.

[0038] Figure 4 It is a schematic diagram of the working principle of the energy storage voltage stabilizer.

[0039] Figure 5 It is a schematic diagram of the principle of the hydrodynamic parameter acquisition system.

[0040] The meanings of each label in the figure are as follows: 1 - water storage tank, 2 - water pump, 3 - check valve, 4 - rock chamber, 5 - simulated drilling pipe, 6 - flange end cover, 7 - return water port sealing head, 8 - return water valve, 9 - energy storage voltage stabilizer, 10 - acoustic wave sensing armored optical cable, 11 - optical fiber sealing head, 12 - hydrodynamic parameter acquisition system, 13 - water supply valve, 14 - high-pressure pipeline, 15 - distributed acoustic wave sensing system.

[0041] 401 - rock chamber main body, 402 - rock chamber cap, 403 - connector, 404 - water outlet plate, 405 - simulated water outlet, 406 - lithology simulation cavity.

[0042] 901 - energy storage device, 902 - first electromagnetic flow valve, 903 - second electromagnetic flow valve, 904 - drain valve.

[0043] 90101 - energy storage tank, 90102 - energy storage tank water inlet valve, 90103 - energy storage tank drain valve, 90104 - overflow valve, 90105 - pressure gauge.

[0044] 1201 - computer terminal, 1202 - 485 to USB communication module, 1203 - analog signal acquisition board, 1204 - 24V power module, 1205 - liquid turbine flowmeter, 1206 - pressure transmitter.

[0045] The following further elaborates on the specific content of the present invention in conjunction with embodiments. Specific Embodiments

[0046] It should be noted that all the devices and methods in the present invention, unless otherwise specified, all adopt the devices and methods known in the prior art.

[0047] In the present invention, the thickness range of the extremely thick aquifer is 200m to 500m and above.

[0048] In the present invention, the relatively water-rich layer is divided according to the magnitude of the specific yield q: q > 10 L / (s·m) is extremely strong water-richness; 1 < q < 10 L / (s·m) is strong water-richness; 0.1 < q < 1 L / (s·m) is medium water-richness; 0.01 < q < 0.1 L / (s·m) is weak water-richness: q < 0.01 L / (s·m) is extremely weak water-richness.

[0049] To achieve a detailed exploration of the extremely thick aquifer in the underground rock formation, it is urgent to establish a physical device for simulation experiments under controlled conditions. This device should be able to simulate the water outlet states under different flow rates, lithologies, and outlet sizes, so as to study the relationship between acoustic signals and the water outlet velocity / flow rate of the water-rich section of the aquifer, and based on this, construct an accurate mathematical model of flow rate and acoustic characteristics. Through the application of this physical simulation experimental device, the accuracy of the DAS technology in exploring the relatively water-rich section of the extremely thick aquifer in the underground rock formation can be effectively improved, providing a reliable theoretical basis and technical support for future on-site applications.

[0050] Therefore, the research and development of a physical simulation experimental device combined with DAS technology and a method for exploring the water-rich section can not only make up for the deficiencies of traditional technologies but also meet the requirements of coal mine safety production for high-precision exploration technologies. This innovative technology will provide strong technical support for the prevention and control of water hazards in extremely thick rock aquifers and has broad practical application prospects, providing important support for the efficient, safe, and sustainable mining of coal mines.

[0051] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and any equivalent transformation based on the technical solutions of this application falls within the protection scope of the present invention.

[0052] Embodiment 1:

[0053] This embodiment provides a physical simulation experimental device for detailed exploration of the water outlet section of the underground rock formation, as Figure 1 shown, including a water storage tank 1. The water storage tank 1 is connected to a water pump 2. The water pump 2 is connected to one end of a plurality of water supply valves 13 through a one-way valve 3. The other end of each water supply valve 13 is correspondingly connected to a rock chamber 4. The plurality of rock chambers 4 are vertically installed on the side wall of a simulated drilling pipe 5.

[0054] As Figure 1 shown, flange end caps 6 are respectively installed at both ends of the simulated drilling pipe 5. A water return port sealing head 7 is installed on the flange end cap 6 at the tail end of the simulated drilling pipe 5. The water return port sealing head 7 is connected to the water storage tank 1 for water return through a water return valve 8.

[0055] As Figure 2 shown, the rock chamber 4 includes a hollow rock chamber main body 401. A rock chamber cap 402 is installed at the top of the rock chamber main body 401. The rock chamber cap 402 is communicated with the water supply valve 13. The bottom end of the rock chamber main body 401 is detachably installed at the top end of a hollow connector 403. The bottom end of the connector 403 is connected to the side wall of the simulated drilling pipe 5. A replaceable water outlet plate 404 is clamped inside the connector 403. A simulated water outlet 405 is provided through the middle of the water outlet plate 404. The cavity between the water outlet plate 404, the connector 403, the rock chamber main body 401, and the rock chamber cap 402 is a lithology simulation cavity 406.

[0056] As Figure 1 shown, an energy storage and voltage stabilizer 9 is also provided between the water storage tank 1 and one end of a plurality of water supply valves 13.

[0057] As Figure 1 shown, an acoustic sensing armored optical cable 10 is coaxially installed inside the simulated drilling pipe 5, and both ends of the acoustic sensing armored optical cable 10 extend out of the flange end covers 6 at both ends of the simulated drilling pipe 5.

[0058] As Figure 4 shown, a liquid turbine flowmeter 1205 and a pressure transmitter 1206 are respectively and correspondingly installed on the high-pressure pipelines 14 between each water supply valve 13 and the rock chamber 4.

[0059] In this embodiment, the various devices are mainly connected through the high-pressure pipeline 14. The maximum pressure-bearing capacity of the high-pressure pipeline 14 is 34 MPa, meeting the pressure requirements under different experimental conditions.

[0060] In this embodiment, the water storage tank 1 is used to store the water source required for the experiment to ensure the continuous supply of the water source.

[0061] As a preferred solution of this embodiment, the water pump 2 adopts a reciprocating piston pump. In this embodiment, the reciprocating piston pump is used to provide hydrodynamic power for the experiment, and can maintain the uniformity of the water flow under different flow rate conditions, ensuring a smooth transition from low flow rate to high flow rate.

[0062] As a preferred solution of this embodiment, there are three rock chambers 4, which are respectively placed at positions 12.64 - 12.83 m, 18.47 - 18.66 m, and 20.54 - 20.73 m away from the first end of the simulated drilling pipe 5.

[0063] In this embodiment, the rock chamber 4 is used to simulate the acoustic response of groundwater flow under different lithology conditions. The outer diameter of the rock chamber 4 is 80 mm, the inner diameter is 54 mm, and the length is 130 mm, which is made of 20# steel pipe.

[0064] In this embodiment, the material of the water outlet plate 404 is 20# steel pipe, the diameter of the circular simulated water outlet 405 is 3 - 9 mm, and the side length of the square simulated water outlet 405 is 3 - 12 mm. Different shapes and different sizes of water outlets can generate different hydrodynamic sound waves. The water outlet conditions under actual working conditions are simulated through the simulated water outlets 405 with different shapes and different sizes.

[0065] In this embodiment, different sandstones can be loaded inside the lithology simulation cavity 406 to simulate different lithologies.

[0066] In this embodiment, the simulated drilling pipe 5 is used to reproduce the flow of groundwater under different flow velocities, lithologies, and outlet conditions, and accurately reproduce the hydrodynamic environment in an actual drill hole. The simulated drilling pipe 5 is made of 20# stainless steel, with a diameter of 177.8 mm and a total length of 30.56 m. It is formed by screwing together thirty-one 0.95 m steel pipes and three 0.2 m steel pipes. The total length of the simulated drilling pipe 5 being 30.56 m avoids the influence of acoustic wave reflections at both ends on the acoustic wave measurement at the outlet due to the simulated drill hole being too short.

[0067] As a specific solution of this embodiment, as Figure 3 shown, the energy storage pressure stabilizer 9 includes a plurality of energy storage devices 901. The energy storage device 901 includes an energy storage tank 90101. An energy storage tank inlet valve 90102, an energy storage tank drain valve 90103, and an overflow valve 90104 are installed in parallel on the energy storage tank 90101. A pressure gauge 90105 is provided between the energy storage tank 90101 and the overflow valve 90104.

[0068] As Figure 4 shown, the energy storage pressure stabilizer 9 further includes a first electromagnetic flow valve 902 and a second electromagnetic flow valve 903 connected in parallel. One end of the first electromagnetic flow valve 902 and one end of the second electromagnetic flow valve 903 are both connected to one end of a plurality of water supply valves 13; the other end of the first electromagnetic flow valve 902 is connected to the energy storage tank inlet valve 90102 of the first group of energy storage devices 901 connected in parallel. The energy storage tank drain valve 90103 and the overflow valve 90104 of the first group of energy storage devices 901 connected in parallel are connected to the water storage tank 1; the other end of the second electromagnetic flow valve 903 is connected to the energy storage tank inlet valve 90102 of the second group of energy storage devices 901 connected in parallel. The energy storage tank drain valve 90103 and the overflow valve 90104 of the second group of energy storage devices 901 connected in parallel are connected to the water storage tank 1.

[0069] Further preferably, as Figure 4 shown, one end of the first electromagnetic flow valve 902 and one end of the second electromagnetic flow valve 903 are both connected to one end of the same drain valve 904. The other end of the drain valve 904 is connected to the water storage tank 1. The drain valve 904 is used to control the discharge of the remaining water in the energy storage pressure stabilizer 9 after the experiment.

[0070] In this embodiment, the energy storage pressure stabilizer 9 is used to maintain the stability of the water flow pressure and avoid the influence of water pressure fluctuations on the flow rate and experimental results. The energy storage pressure stabilizer 9 is a simulation of the hydrodynamic condition control link, achieving the initial hydrodynamic conditions of stable water pressure and water flow rate at the beginning of the experiment, avoiding the influence of sudden increases and decreases in water pressure pulsation during the water injection of the water pump 2 on the flow rate and experimental results, as well as the hydrodynamic conditions of the stable decrease in water flow rate in the later stage of the experiment.

[0071] In this embodiment, the capacity of the energy storage tank 90101 is 100 L.

[0072] As a further preferred solution of this embodiment, as Figure 5 shown, it further includes a hydrodynamic parameter acquisition system 12. The hydrodynamic parameter acquisition system 12 includes a computer terminal 1201. The computer terminal 1201 is connected to an analog signal acquisition board 1203 through a 485-to-USB communication module 1202. The analog signal acquisition board 1203 is connected to a 24V power module 1204. The analog signal acquisition board 1203 is also respectively connected to a liquid turbine flowmeter 1205 and a pressure transmitter 1206 to collect signals. The liquid turbine flowmeter 1205 and the pressure transmitter 1206 are also connected to the 24V power module 1204 to obtain power.

[0073] In this embodiment, the computer terminal 1201, the 485-to-USB communication module 1202, the analog signal acquisition board 1203, and the 24V power module 1204 all adopt devices known in the art.

[0074] As a preferred solution of this embodiment, as Figure 1 shown, the acoustic wave sensing armored optical cable 10 is connected to the flange end cover 6 through an optical fiber sealing head 11.

[0075] In this embodiment, the acoustic wave sensing armored optical cable 10 is used for acoustic wave sensing. A high-precision steel pipe armored optical cable is adopted to ensure the stability and low noise of signal transmission. A high-performance and durable armored optical cable is adopted, reducing the maintenance frequency and cost, thereby improving the overall reliability and service life of the system.

[0076] As a preferred solution of this embodiment, as Figure 1 shown, the acoustic wave sensing armored optical cable 10 is connected to a distributed acoustic wave sensing system 15.

[0077] In this embodiment, the distributed acoustic wave sensing system 15 adopts a distributed acoustic wave sensing system known in the art. The distributed acoustic wave sensing system 15 is used to collect in real time the acoustic wave signals generated by the water flow in the simulated borehole, analyze the acoustic wave signals in real time, extract acoustic wave characteristics and invert flow data, and display the acoustic wave signals and related data in real time.

[0078] Embodiment 2:

[0079] This embodiment provides a physical simulation experiment method for fine exploration of the water-producing layer section of underground rock formations. This physical simulation experiment method uses the physical simulation experiment device for fine exploration of the water-producing layer section of underground rock formations given in Embodiment 1.

[0080] In this embodiment, the indoor simulation experiment is a key step to verify the concept and performance of DAS in the exploration of the water-rich layer section of the sandstone aquifer in underground rock formations. This embodiment designs a flow rate change simulation experiment to simulate the acoustic wave propagation environment at different flow velocities in the underground aquifer.

[0081] In this embodiment, the flow rate of water flowing into the simulated borehole is controlled by adjusting the injection pressure. The length of the acoustic sensing armored optical cable 10 is 140 m, the length of the simulated borehole pipe 5 is 30.56 m, the simulated water outlet 405 is at the 87 m position of the optical fiber, and the simulated borehole pipe 5 is at the 68.34 m to 98.9 m positions of the optical fiber.

[0082] In the embodiment, an initial pressure of 4 MPa and an initial flow rate of 1 m 3 / h are adopted, and the stop flow rate is 0.1 m 3 / h to simulate the water outlet acoustic waves under different flow velocity conditions in the steady state.

[0083] In this embodiment, four different types of sandstones, namely fine-grained sandstone, medium-grained sandstone, coarse-grained sandstone, and conglomerate, are adopted to simulate the water outlet acoustic waves under different lithologic aquifer conditions.

[0084] In this embodiment, four circular simulated water outlets 405 with different sizes are adopted, and the inner diameters are φ = 3 mm, φ = 5 mm, φ = 7 mm, and φ = 9 mm respectively, to simulate the water outlet acoustic waves under different water outlet size conditions.

[0085] In this embodiment, after each replacement of the simulated water outlet 405, a variety of different sandstones designed in the experiment are sequentially simulated, and each sandstone needs to collect data under a variety of flow rate conditions. This process ensures the integrity of the experimental data under each combination condition of the water outlet, sandstone, and flow rate, facilitating a comprehensive analysis of the acoustic wave generation and propagation characteristics in the relatively water-rich layer section of the aquifer and establishing an accurate flow rate model.

[0086] Specifically, this physical simulation experiment method includes the following experimental steps:

[0087] Step 1, start the monitoring system:

[0088] Turn on the distributed acoustic sensing system 15 (i.e., the DAS system), and set the acquisition parameters, such as the sampling frequency, sampling interval, and data storage length. In this embodiment, the acquisition mode is differential data, the sampling frequency is 4 kHz, the sampling interval is 0.5 m, and the single data storage duration is 30 s.

[0089] At the same time, start the hydrodynamic parameter acquisition system 12, and set the unit of the flow rate and the sampling frequency. In this embodiment, the flow rate unit is m3 / h, and the acquisition frequency is 1 Hz.

[0090] Synchronize the system time of the hydrodynamic parameter acquisition system 12 and the distributed acoustic sensing system 15 to achieve effective data comparison and analysis.

[0091] Step 2, set the simulated water outlet:

[0092] Install the water outlet plate 404 with the first type of simulated water outlet 405 (such as a circular diameter of 3 mm) at the bottom of the lithology simulation cavity 406 of the rock bin 4, ensure firm installation, and install a screen at the simulated water outlet 405 to prevent sand grains from entering the simulated drilling pipe 5, ensuring the reliability and continuity of the experiment.

[0093] Step 3, load the first type of sandstone:

[0094] Select the sandstone with the particle size required for the first type of experiment (such as fine-grained sandstone), and evenly load it into the lithology simulation cavity 406, ensuring that the sandstone is tightly packed and evenly distributed to avoid experimental errors caused by uneven sand filling. Connect the connector 403 of the rock bin 4 to the simulated drilling pipe 5, and connect the rock bin cap 402 of the rock bin 4 to the water supply valve 13 through the high-pressure pipeline 14 to ensure accurate simulation of the experimental conditions.

[0095] Step 4, water injection and pressure stabilization adjustment:

[0096] Start the water pump 2, fill the rock bin 4 and the simulated drilling pipe 5 with water through the water supply valve 13, and close all the water supply valves 13. The water storage tank 1 injects water into the energy storage pressure stabilizer 9 through the water pump 2 and the one-way valve 3 until the maximum experimental pressure (such as: 1 MPa, 2 MPa, 3 MPa, 4 MPa), and then turn off the water pump 2.

[0097] Open the return water valve 8 and the water supply valve 13, inject water into the rock bin 4 and the simulated drilling pipe 5 through the energy storage pressure stabilizer 9, and control the initial water injection flow rate by adjusting the water supply valve 13, such as setting it to 1 m 3 / h, and use the energy storage pressure stabilizer 9 to ensure high-quality data collection of acoustic signals under stable flow conditions.

[0098] Step 5, data collection:

[0099] Start collecting data from the initial stable flow rate, such as 1 m 3 / h, and continue until the minimum flow rate designed for the flow experiment, such as 0.1 m 3 / h, and then stop data collection.

[0100] Step 6, replace with other sandstones:

[0101] Replace with the second type of sandstone, which is medium-grained sandstone in this embodiment, in the same way as in Step 3, and repeat Steps 4 to 5.

[0102] Replace with the third type of sandstone, which is coarse-grained sandstone in this embodiment, in the same way as in Step 3, and repeat Steps 4 to 5.

[0103] Replace with the fourth type of sandstone, which is conglomerate in this embodiment, in the same way as in Step 3, and repeat Steps 4 to 5.

[0104] Step 7, replace with other simulated water outlets:

[0105] Replace the second simulated water outlet 405 with a circular diameter of 5 mm in the same way as in Step 2, and repeat Steps 3 to 6.

[0106] Replace the third simulated water outlet 405 with a circular diameter of 7 mm in the same way as in Step 2, and repeat Steps 3 to 6.

[0107] Replace the third simulated water outlet 405 with a circular diameter of 9 mm in the same way as in Step 2, and repeat Steps 3 to 6.

[0108] If it is necessary to test simulated water outlets of other shapes (such as squares or rectangles), further experiments shall be carried out according to the experimental objectives.

[0109] Step 8, Shut down the equipment and data processing:

[0110] After the experiment, close the water supply valve 13 and the return water valve 8, turn off the hydrodynamic parameter acquisition system 12, and turn off the distributed acoustic sensing system 15 to ensure the safe shutdown of the equipment. Then open the drain valve 904 to empty the remaining water in the energy storage and pressure stabilizer 9, and thoroughly clean the equipment to ensure its normal operation in subsequent experiments.

[0111] Next, conduct a detailed analysis of all the acoustic data collected. Combine different flow rates, sandstones, and simulated water outlet conditions to extract sensitive acoustic characteristics related to the water-rich layer section. Finally, establish and verify the mathematical model between the acoustic data and the flow rate changes, so as to improve the accuracy and reliability of the exploration of the water-rich layer section in the underground rock formation.

Claims

1. A physical simulation experimental device for fine exploration of water-producing intervals in underground rock formations, comprising a water storage water tank (1), the water storage water tank (1) being connected to a water pump (2), characterized in that, The water pump (2) is connected to one end of multiple water supply valves (13) through a check valve (3). The other end of each water supply valve (13) is correspondingly connected to a rock chamber (4). The multiple rock chambers (4) are vertically installed on the side wall of the simulated drilling pipe (5). Flange end caps (6) are respectively installed at both ends of the simulated drilling pipe (5). A water return port seal head (7) is installed on the flange end cap (6) at the tail end of the simulated drilling pipe (5). The water return port seal head (7) is connected to the water storage tank (1) through a water return valve (8) for water return. The rock chamber (4) includes a hollow rock chamber main body (401). A rock chamber cap (402) is installed at the top end of the rock chamber main body (401). The rock chamber cap (402) is communicated with the water supply valve (13). The bottom end of the rock chamber main body (401) is detachably installed at the top end of a hollow connector (403). The bottom end of the connector (403) is connected to the side wall of the simulated drilling pipe (5). A replaceable water outlet plate (404) is clamped inside the connector (403). A simulated water outlet (405) is provided through the middle of the water outlet plate (404). The cavity between the water outlet plate (404), the connector (403), the rock chamber main body (401), and the rock chamber cap (402) is a lithology simulation cavity (406). An energy storage voltage stabilizer (9) is also provided between the water storage tank (1) and one end of multiple water supply valves (13). An acoustic wave sensing armored optical cable (10) is coaxially installed inside the simulated drilling pipe (5). Both ends of the acoustic wave sensing armored optical cable (10) extend out of the flange end caps (6) at both ends of the simulated drilling pipe (5). A liquid turbine flowmeter (1205) and a pressure transmitter (1206) are respectively installed on the high-pressure pipelines (14) between each water supply valve (13) and the rock chamber (4).

2. The physical simulation experimental device for fine exploration of water-producing sections of underground rock formations according to claim 1 is characterized in that: The energy storage voltage stabilizer (9) includes multiple energy storage devices (901). The energy storage device (901) includes an energy storage tank (90101). An energy storage tank inlet valve (90102), an energy storage tank drain valve (90103), and an overflow valve (90104) are installed in parallel on the energy storage tank (90101). A pressure gauge (90105) is provided between the energy storage tank (90101) and the overflow valve (90104). The energy storage voltage stabilizer (9) further includes a first electromagnetic flow valve (902) and a second electromagnetic flow valve (903) connected in parallel. One end of the first electromagnetic flow valve (902) and one end of the second electromagnetic flow valve (903) are both connected to one end of the plurality of water supply valves (13); the other end of the first electromagnetic flow valve (902) is connected to the energy storage tank water inlet valve (90102) of the first group of parallel energy storage devices (901), and the energy storage tank drain valve (90103) and the overflow valve (90104) of the first group of parallel energy storage devices (901) are connected to the water storage tank (1); the other end of the second electromagnetic flow valve (903) is connected to the energy storage tank water inlet valve (90102) of the second group of parallel energy storage devices (901), and the energy storage tank drain valve (90103) and the overflow valve (90104) of the second group of parallel energy storage devices (901) are connected to the water storage tank (1).

3. The physical simulation experimental device for fine exploration of the water-producing section of underground rock formations according to claim 2, characterized in that, One end of the first electromagnetic flow valve (902) and one end of the second electromagnetic flow valve (903) are both connected to one end of the same drain valve (904), and the other end of the drain valve (904) is connected to the water storage tank (1).

4. The physical simulation experimental device for fine exploration of the water-producing interval in underground rock formations according to claim 1, characterized in that, It further includes a hydrodynamic parameter acquisition system (12). The hydrodynamic parameter acquisition system (12) includes a computer terminal (1201). The computer terminal (1201) is connected to an analog signal acquisition board (1203) through a 485-to-USB communication module (1202). The analog signal acquisition board (1203) is connected to a 24V power supply module (1204). It is characterized in that the analog signal acquisition board (1203) is further respectively connected to a liquid turbine flowmeter (1205) and a pressure transmitter (1206) to acquire signals, and the liquid turbine flowmeter (1205) and the pressure transmitter (1206) are also connected to the 24V power supply module (1204) to obtain power.

5. The physical simulation experimental device for fine exploration of water-producing layer sections of underground rock formations according to claim 1 is characterized in that: The water pump (2) uses a reciprocating piston pump.

6. The physical simulation experimental device for fine exploration of the water-producing interval in underground rock formations according to claim 1, wherein, There are three rock chambers (4), which are respectively placed at positions 12.64 - 12.83 m, 18.47 - 18.66 m, and 20.54 - 20.73 m from the head end of the simulated drilling pipe (5).

7. The physical simulation experimental device for fine exploration of the water-producing interval in underground rock formations according to claim 1, wherein The acoustic sensing armored optical cable (10) is connected to the flange end cover (6) through an optical fiber seal head (11).

8. The physical simulation experimental device for fine exploration of water-producing sections of underground rock formations according to claim 1 is characterized in that: The acoustic sensing armored optical cable (10) is connected to a distributed acoustic sensing system (15).

9. A physical simulation experimental method for fine exploration of water-producing sections of underground rock formations, characterized in that: This physical simulation experiment method uses the physical simulation experiment device for fine exploration of the underground rock formation water outlet section as described in any one of claims 1 to 8.

10. The physical simulation experiment method for fine exploration of the water-producing interval in underground rock formations according to claim 9, characterized in that, The sandstones filled in the lithology simulation chamber (406) are respectively fine-grained sandstone, medium-grained sandstone, coarse-grained sandstone or conglomerate; The shape of the simulated water outlet (405) is circular or square. The inner diameter of the circular simulated water outlet (405) is 3 mm, 5 mm, 7 mm or 9 mm.

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