A rock wave speed dynamic monitoring system for simulating gas content change of a hydrocarbon source rock

Abstract

The application discloses a rock wave velocity dynamic monitoring system for simulating gas content change of a hydrocarbon source rock, which comprises a rock wave velocity and desorbed gas combined monitoring system, a terminal operation and gas storage system, a gas supply system, a desorbed gas recovery system, a state display, a total gas path and a constant temperature system; the total gas path comprises a first gas path, a second gas path and a unit gas path; the terminal operation and gas storage system and the gas supply system are connected in communication by the first gas path; the rock wave velocity and desorbed gas combined monitoring system and the terminal operation and gas storage system are connected in communication by the second gas path; and the sample cylinder, the reference cylinder and the desorbed gas recovery system in the rock wave velocity and desorbed gas combined monitoring system are connected in communication by the unit gas path. The application can carry out isothermal desorption experiments under different temperature, different gas pressure and different lithology multi-factor coupling conditions, can truly simulate the gas desorption rate of the hydrocarbon source rock in unconventional natural gas production engineering, and can complete dynamic data determination.

Description

Technical Field

[0001] This invention relates to multiple fields such as unconventional natural gas exploration, geophysical exploration, and rock physics, specifically a dynamic monitoring system for rock wave velocity that simulates changes in the gas content of source rocks. Background Technology

[0002] Accurately determining rock wave velocity through experimental methods is one of the key scientific issues of concern in the field of geophysics both domestically and internationally. Rock wave velocity is a very important kinematic characteristic parameter in the field of seismic exploration, and precise stratigraphic rock wave velocity is required for detailed geological and geophysical modeling and stratigraphic lithology interpretation.

[0003] The lithology, burial depth (temperature, pressure), and fluid saturation (oil and gas content) of rocks are important factors affecting rock wave velocity. Currently, a series of in-depth studies have been carried out on the determination of rock wave velocity under temperature and pressure variation environments (Birch, 1961; Fang Weiqing, 1962; Xie Hongsen et al., 1993; Liu Yongxiang et al., 1995; Liu Xi et al., 2017; Mao Zhu et al., 2022). Birch first published the longitudinal wave velocity of rocks under high pressure in 1961; Fang Weiqing (1962) measured the elastic modulus parameters of diabase, basalt, granite, and limestone under 1–1000 Pa using static and dynamic methods; Xie Hongsen et al. (1993) established a new method for measuring the elastic wave velocity of high-temperature and high-pressure rocks on a tightly fitted six-sided high-pressure device, which can simultaneously measure both longitudinal and transverse wave velocities. Liu Yongxiang et al. (1995) studied the properties of rock elastic wave velocity under high pressure and created a pressure-temperature-velocity (P-TV) contour map in 1997, producing a density-wave velocity diagram of deep rocks. However, to date, there is no device or system for dynamically measuring rock wave velocity during changes in oil and gas content.

[0004] Existing rock wave velocity detection instruments only focus on measuring rock wave velocity under high temperature and high pressure environments, such as (CN108120768A; CN110618198B; Zhao Zhidan, 1996; Jiang Xi et al., 2013; Zang Chunjuan et al., 2014), which effectively simulates the characteristics of rock wave velocity changes at different burial depths. However, in actual oil and gas production, the thickness and depth of the oil and gas reservoirs we are concerned with are often fixed, but with the production of oil and gas, the hydrocarbon gas content in the reservoir will show a non-linear decreasing trend. When the gas in the rock pores escapes, according to the Wyllie equation (Equation 1), the rock wave velocity will change accordingly. However, existing rock wave velocity detection instruments cannot monitor the dynamic change trend of rock wave velocity with its gas content, and cannot obtain accurate rock wave velocities of oil and gas reservoirs at different gas content stages.

[0005]

[0006] In the formula, V is the actual layer velocity of the wave in the rock; V f V is the velocity of the wave in the pore fluid of the rock; r φ is the wave velocity in the rock matrix; φ is the rock porosity; C is the pressure differential adjustment coefficient.

[0007] In summary, the efficient development and high-quality development of unconventional oil and gas reservoirs rely heavily on time-lapse seismic monitoring (TLS). However, as reservoir oil and gas production decreases, the resulting decline in reservoir hydrocarbon content alters rock wave velocity. This change in rock wave velocity affects the accuracy of geophysical modeling and stratigraphic lithology interpretation during seismic exploration. Therefore, we propose a dynamic rock wave velocity monitoring system that simulates changes in source rock gas content. Through experimental methods, we reveal the trend of rock wave velocity variation with hydrocarbon content, providing crucial scientific reference for more accurate time-lapse seismic monitoring, geophysical modeling, and stratigraphic lithology interpretation of unconventional oil and gas reservoirs. Summary of the Invention

[0008] To address the problems mentioned in the background art, this invention provides a dynamic monitoring system for rock wave velocity that simulates changes in the gas content of source rocks. By isothermally and isobarically desorbing adsorbed gas in source rocks, the system monitors the gas content and rock wave velocity of source rocks under different desorption degrees, thereby achieving a dynamic monitoring effect that simulates changes in rock wave velocity during actual underground reservoir oil and gas production. This provides an important reference for time-lapse seismic geological modeling and lithological interpretation in exploration areas.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is: a dynamic monitoring system for rock wave velocity that simulates changes in the gas content of source rocks, characterized in that it includes a joint monitoring system for rock wave velocity and desorbed gas, a terminal operation and gas storage system, a gas supply system, a desorbed gas recovery system, a status display, a main gas path, and a constant temperature system.

[0010] The overall gas path includes a first gas path, a second gas path, and unit gas paths. The terminal operation and gas storage system is connected to the gas supply system via the first gas path. The rock wave velocity and desorbed gas joint monitoring system is connected to the terminal operation and gas storage system via the second gas path. The sample cylinder, reference cylinder, and desorbed gas recovery system within the rock wave velocity and desorbed gas joint monitoring system are connected via unit gas paths.

[0011] The constant temperature system is used to control and maintain the temperature of the rock wave velocity and desorbed gas joint monitoring system and the desorbed gas recovery system.

[0012] Furthermore, the rock wave velocity and desorbed gas joint monitoring system includes a desorption cylinder, a reference cylinder, and a gas pressure sensor. The desorption cylinder includes a high-pressure resistant and heat-insulated outer cylinder and a sample cylinder. The sample cylinder is located inside the high-pressure resistant and heat-insulated outer cylinder. An ultrasonic pulse penetration device and an ultrasonic receiving device are respectively installed at the upper and lower ends of the sample cylinder. At the same time, the sample cylinder is connected to the reference cylinder through a unit gas path, and the reference cylinder is connected to the terminal operation and gas storage system through a second gas path. The gas paths between the sample cylinder, the reference cylinder, the terminal operation, and the gas storage system are all controlled by independent electrically controlled gas valves, which individually control the intake and exhaust functions of each unit.

[0013] Furthermore, the ultrasonic pulse penetration device is connected to a spring coupling device and a conductive sheet. The spring coupling device tightly couples the ultrasonic pulse device to the top of the core sample, ensuring the accuracy of rock wave velocity measurement.

[0014] Furthermore, the ultrasonic pulse penetration device includes an ultrasonic pulser, a conductive buffer pad, an air inlet, a connecting circuit, a rock sample coupling top plate, and a pulser latch. The ultrasonic receiving device includes an ultrasonic receiver and a rock sample coupling bottom plate. The ultrasonic pulser is fixed to the rock sample coupling top plate via the pulser latch. The rock sample coupling top plate is connected to the sample cylinder cover plate via a spring coupling device, and the relative position of the coupling top plate inside the cylinder is controlled by the spring coupling device to ensure that the coupling top plate is in close contact with the top of the rock sample. The coupling bottom plate is fixed to the bottom of the sample cylinder to ensure that it is in close contact with the bottom of the rock sample.

[0015] Furthermore, each branch gas path of the reference cylinder and sample cylinder is equipped with a gas pressure sensor to monitor the gas pressure changes of different units in real time.

[0016] Furthermore, the terminal operation and gas storage system has data display and gas storage functions. The terminal operating system is connected to the gas pressure sensor and ultrasonic pulse penetration device of each unit through circuitry to ensure real-time recovery and display of rock wave velocity and gas pressure monitoring data. The gas storage system is connected to the gas supply system through the first gas path for temporary storage and mixing of gas, and is also connected to the rock wave velocity and desorbed gas joint monitoring system through the second gas path for regulating gas pressure and distributing it to each independent unit.

[0017] Furthermore, the gas supply system includes three independent gas tanks, which can be filled with different components of gas according to experimental requirements, and each gas tank is connected to an independent pressure gauge.

[0018] Furthermore, the desorption gas recovery system is connected to the sample cylinder through a unit gas path to temporarily store the desorption gas and regulate the gas pressure in the sample cylinder, while avoiding the direct discharge of desorption gas, which could cause safety hazards and environmental pollution.

[0019] Furthermore, the status display includes a gas pressure sensor status light and an ultrasonic pulse device status light group, which are connected to the ultrasonic pulse penetration device, the gas pressure sensor, the terminal operation and the gas storage system through circuitry to monitor the working status of the ultrasonic pulse penetration device and the gas pressure sensor in real time.

[0020] Furthermore, the constant temperature system includes a top-open heating chamber and methyl silicone oil for temperature control and insulation during the experiment.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention utilizes a combined monitoring system for rock wave velocity and desorbed gas to accurately determine the dynamic variation trend of rock wave velocity in source rocks under different desorption gas pressures. A spring coupling device ensures close coupling of the ultrasonic pulse device to the top of the core sample, guaranteeing the accuracy of rock wave velocity measurements. A conductive buffer pad on the coupling top plate reduces the impact of the instantaneous release of spring kinetic energy on the coupling top plate, preventing longitudinal displacement and minimizing experimental errors. Four circular air inlets on the coupling top plate ensure unobstructed gas flow when the coupling top plate is in close contact with the core sample. A gas storage system and a constant temperature system provide experimental environments with different pressures and temperatures, enabling combined measurements of source rock gas desorption and rock wave velocity under varying temperatures and pressures.

[0023] This invention enables dynamic monitoring experiments of rock wave velocity under varying gas content in source rocks, and allows for isothermal desorption experiments under multiple coupled conditions of different temperatures, gas pressures, and lithologies. It can realistically simulate the gas desorption rate of source rocks in unconventional natural gas drainage projects, and dynamically measure the trend of rock wave velocity with desorbed gas content at different drainage stages. The experimental apparatus is simple to operate, effective, and easily promoted. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of the rock wave velocity and desorbed gas joint monitoring system of the present invention;

[0026] Figure 3 This is a schematic diagram of the internal structure of the rock wave velocity measuring device and desorption cylinder of the present invention;

[0027] In the diagram: 1. Terminal operation and gas storage system; 11. Data display; 12. Main gas pressure gauge; 13. Electrical control switch; 2. Gas supply system; 21. Pressure gauge; 22. Gas storage tank; 3. Rock wave velocity and desorbed gas joint monitoring system; 31. High-pressure resistant and heat-insulated outer cylinder; 32. Sample cylinder; 33. Ultrasonic pulse penetration device; 331. Ultrasonic pulser; 332. Conductive buffer pad; 333. Air inlet; 334. Connecting circuit; 335. Rock sample coupling top plate; 336. Pulser latch; 34. 1. Ultrasonic receiving device; 341. Ultrasonic receiver; 342. Rock sample coupling base plate; 35. Conductive sheet; 36. Spring coupling device; 37. Reference cylinder; 38. Gas pressure sensor; 4. Status display; 41. Gas pressure sensor status light; 42. Ultrasonic pulse device status light group; 5. Desorption gas recovery system; 6. Main gas path; 61. Ultra-high pressure gas pipe; 62. Electrically controlled gas valve; 63. First gas path; 64. Second gas path; 65. Unit gas path; 7. Main circuit; 8. Constant temperature system. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] Please see Figure 1-3 This invention provides a dynamic monitoring system for rock wave velocity to simulate changes in the gas content of source rocks. The system includes a terminal operation and gas storage system 1, a gas supply system 2, a combined rock wave velocity and desorbed gas monitoring system 3, a status display 4, a desorbed gas recovery system 5, a main gas path 6, a main circuit 7, and a constant temperature system 8. The main gas path 6 includes a first gas path 63, a second gas path 64, and a unit gas path 65. The terminal operation and gas storage system 1 and the gas supply system 2 are connected via the first gas path 63. The terminal operation and gas storage system 1 and the combined rock wave velocity and desorbed gas monitoring system 3 are connected via the second gas path 64. The sample cylinder 32, the reference cylinder 37, and the desorbed gas recovery system 5 of the combined rock wave velocity and desorbed gas monitoring system 3 are connected via the unit gas path 65. Furthermore, each gas path between components is controlled by an independent electrically controlled gas valve 62 to ensure airtightness and the independence of each unit during the experiment.

[0030] Please see Figure 1-2 The main circuit 7 is responsible for connecting the terminal operation and gas storage system 1, the ultrasonic pulse penetration device 33, and the gas pressure sensor 38. It can transmit the monitored gas pressure and rock wave velocity data to the terminal operation and gas storage system 1 and display them in real time on the data display 11, which is convenient for experimental operators to carry out data verification and analysis.

[0031] Please see Figure 1The gas supply system 2 includes three independent gas storage tanks 22, each independently connected to a pressure gauge 21, allowing for flexible mixing of experimental gases. In actual use, during conventional experiments, the three independent gas storage tanks store 99.9% high-purity gases of three different components: low-pressure helium (3 MPa), high-pressure methane (12 MPa), and high-pressure carbon dioxide (12 MPa). Low-pressure helium is an inert gas and is not adsorbed by the pores of the source rock, allowing for the determination of the free space volume of the reference cylinder and sample cylinder. High-pressure methane and carbon dioxide can be mixed in the terminal operation and gas storage system 1, and the mixing ratio of the mixed gases can be flexibly adjusted according to experimental requirements and the type of core sample. Simultaneously, the terminal operation and gas storage system 1 is equipped with a total gas pressure gauge 12 and a total gas valve switch 13, which can regulate the gas pressure ultimately delivered to each experimental unit.

[0032] Please see Figure 1 The desorption gas recovery system 5 is connected to the sample cylinder 32 through the unit gas path, which can temporarily store the desorption gas from the source rock. Finally, it is connected to the main gas path 6. After the experiment is completed, the desorption waste gas is directly discharged, or it can be connected to a gas chromatograph to carry out further analysis of the desorption gas components.

[0033] Please see Figure 1 The constant temperature system 8 consists of a top-open heating chamber and methyl silicone oil. When conducting desorption and rock wave velocity measurement experiments, the rock wave velocity and desorbed gas joint monitoring system 3 and the desorbed gas recovery system 5 are immersed in methyl silicone oil, which can play a role in temperature control and heat preservation during the experiment.

[0034] Please see Figure 2 The rock wave velocity and desorbed gas joint monitoring system 3 includes a high-pressure resistant heat-insulated outer cylinder 31, a sample cylinder 32, an ultrasonic pulse penetration device 33, an ultrasonic receiving device 34, a conductive sheet 35, a spring coupling device 36, a reference cylinder 37, and a gas pressure sensor 38. The gas pressure sensor 38 is fixed to the end of each branch gas path of the reference cylinder and the sample cylinder to monitor the gas pressure changes of different units in real time. The ultrasonic pulse penetration device 33 is connected to the spring coupling device 36 and the conductive sheet 35. Through the spring coupling device 36, the ultrasonic pulse device 33 can be tightly coupled to the top of the core sample to ensure the accuracy of rock wave velocity measurement. The status display 4 includes a gas pressure sensor status light 41 and an ultrasonic pulse device status light group 42. It is connected to the ultrasonic pulse penetration device 33, the gas pressure sensor 38, the terminal operation and gas storage system through the circuit 7 to monitor the working status of the ultrasonic pulse penetration device 33 and the gas pressure sensor 38 in real time, ensuring normal operation of the instrument and effective data recovery.

[0035] Please see Figure 3The ultrasonic pulse penetration device 33 includes an ultrasonic pulser 331, a conductive buffer pad 332, an air inlet 333, a connecting circuit 334, a rock sample coupling top plate 335, and a pulser latch 336. The ultrasonic receiving device 34 includes an ultrasonic receiver 341 and a rock sample coupling bottom plate 342. The ultrasonic pulser 331 is fixed to the rock sample coupling top plate 335 through the pulser latch 336. The coupling top plate is connected to the sample cylinder 32 through a spring coupling device 36, and the relative position of the coupling top plate 335 inside the cylinder is controlled by the spring coupling device 36 to ensure that the coupling top plate 335 is in close contact with the top of the rock sample. The coupling bottom plate 342 is fixed to the bottom of the sample cylinder to ensure that it is in close contact with the bottom of the rock sample.

[0036] Please see Figure 3 The conductive buffer pad 332 on the rock sample coupling top plate 335 can reduce the impact of the instantaneous release of spring kinetic energy on the coupling top plate, avoid longitudinal displacement of the coupling top plate, and reduce experimental errors; the four circular air inlets 333 of the coupling top plate can ensure the smooth flow of air when the coupling top plate is in close contact with the rock core sample.

[0037] Working principle and usage process of this invention:

[0038] During the experiment, the volume parameters of the core sample were first measured and recorded. The top cover of the sample cylinder 32 was opened, and the core sample was then placed vertically in the sample cylinder 32, ensuring that the bottom of the core sample was in close contact with the coupling base plate 342. The top cover of the sample cylinder 32 was then pressed down, ensuring that the coupling top plate 335 was in close contact with the top of the core sample under the action of the spring coupling device 36. After the core sample was placed, the rock wave velocity and desorbed gas joint monitoring system 3 and the desorbed gas recovery system 5 were placed in the constant temperature system 8.

[0039] Turn on the ultrasonic pulse penetration device 33 and continuously monitor the rock wave velocity of the core sample until the end of the experiment. By measuring the time it takes for the ultrasonic wave to pass through the core sample, divide the core length by the time to obtain the elastic wave velocity of the ultrasonic wave passing through the experimental sample (Equations 2 and 3). Finally, view the measured rock wave velocity in real time on the data display 11.

[0040] V p =L / t p (2)

[0041] V s =L / t s (3)

[0042] In the formula V p V is the longitudinal wave velocity of the rock. s Let L be the shear wave velocity of the rock, L be the length of the core sample, and t be the velocity of the rock shear wave. p , t sThese represent the time taken for the longitudinal wave and transverse wave to pass through the rock sample, respectively.

[0043] The experimental temperature is set using the constant temperature system 8. After the system temperature stabilizes, the helium cylinder in the gas supply system 2 is opened, and the pressure is adjusted to 0.5 MPa. The first and second gas path electrically controlled valves 62 are opened to charge helium into the gas storage system 1 and the reference cylinder 37, bringing the gas pressure to 0.5 MPa. The gas pressure values ​​of the reference cylinder 37 and the sample cylinder 32 at this time are recorded. Then, the first and second gas path electrically controlled valves 62 are closed, and the electrically controlled valve 62 of the unit gas path between the reference cylinder 37 and the sample cylinder 32 is opened, keeping the reference cylinder 27 and the sample cylinder 32 connected. The cylinders are left to stand for 20 minutes until the gas pressures in the reference cylinder 27 and the sample cylinder 32 stabilize and balance. The gas pressure values ​​of the two cylinders at this time are recorded. The above steps are repeated 3-5 times. The average value of the gas pressure before and after balancing is taken, and the free space volume of the sample cylinder 32 is calculated by substituting it into the corresponding formula. After the free space volume is measured, the first gas path electrically controlled valve 62 is closed, and all the second gas paths and unit gas paths electrically controlled valves 62 are opened to discharge all helium gas from the experimental apparatus.

[0044] Open the methane and carbon dioxide cylinders of gas supply system 2 and adjust the pressure to obtain the required mixed gas ratio (except for the helium cylinder, the other two gases can be flexibly replaced according to experimental needs). Open the first and second gas path electric control valves 62 to charge the experimental gas into the gas storage system 1 and reference cylinder 37, so that the gas pressure reaches 12MPa. Record the gas pressure and rock wave velocity values ​​of reference cylinder 37 and sample cylinder 32 at this time. Then close the first and second gas path electric control valves 62, open the electric control valve 62 of the unit gas path between reference cylinder 37 and sample cylinder 32, keep reference cylinder 27 connected to sample cylinder 32, and let it stand for 12 hours until the rock core sample in sample cylinder 32 reaches the adsorption saturation state. Record the gas pressure and rock wave velocity values ​​of the rock core sample when it reaches the adsorption saturation state.

[0045] After the core sample is saturated with adsorbed gas, the electrically controlled gas valve 62 of the unit gas path between the reference cylinder 37 and the sample cylinder 32 is closed. Using the designed desorption pressure gradient as a threshold (e.g., 10MPa, 8MPa, 6MPa, 4MPa, 2MPa, 0MPa), the electrically controlled gas valve 62 of the unit gas path between the sample cylinder 32 and the desorption gas recovery system 5 is repeatedly opened and closed to reduce the gas pressure in the sample cylinder 32 to the designed pressure gradient threshold. The sample is then left to stand for 12 hours until desorption under negative pressure is complete. The gas pressure and rock wave velocity of the core sample at this desorption pressure point are recorded. The above steps are repeated until the lowest set gas pressure of 0MPa is reached to ensure that the adsorbed gas in the core sample is completely desorbed. The gas pressure and rock wave velocity of the core sample after desorption are recorded. The gas content of the core sample under different desorption pressures is calculated using the corresponding formula. Finally, the dynamic change trend of rock wave velocity with gas content under different desorption pressures is characterized by the combined operation of the terminal and the gas storage system 1.

[0046] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the scope of protection of the present invention in any way, and all technical solutions obtained by equivalent substitution or other means fall within the scope of protection of the present invention.

[0047] All parts not covered in this invention are the same as or can be implemented using existing technologies.

Claims

1. A dynamic monitoring system for rock wave velocity to simulate changes in the gas content of source rocks, characterized in that, The system includes a combined monitoring system for rock wave velocity and desorbed gas; characterized in that it further includes a terminal operation and gas storage system, a gas supply system, a desorbed gas recovery system, a status display, a main gas path, and a constant temperature system. The overall gas path includes a first gas path, a second gas path, and unit gas paths. The terminal operation and gas storage system is connected to the gas supply system via the first gas path. The rock wave velocity and desorbed gas joint monitoring system is connected to the terminal operation and gas storage system via the second gas path. The sample cylinder, reference cylinder, and desorbed gas recovery system within the rock wave velocity and desorbed gas joint monitoring system are connected via unit gas paths. The constant temperature system is used to control and maintain the temperature of the rock wave velocity and desorbed gas joint monitoring system and the desorbed gas recovery system.

2. The rock wave velocity dynamic monitoring system for simulating changes in gas content of source rocks according to claim 1, characterized in that, The rock wave velocity and desorbed gas joint monitoring system includes a desorption cylinder, a reference cylinder, and a gas pressure sensor. The desorption cylinder includes a high-pressure resistant and heat-insulated outer cylinder and a sample cylinder. The sample cylinder is located inside the high-pressure resistant and heat-insulated outer cylinder. An ultrasonic pulse penetration device and an ultrasonic receiving device are respectively installed at the upper and lower ends of the sample cylinder. At the same time, the sample cylinder is connected to the reference cylinder through a unit gas path. The reference cylinder is connected to the terminal operation and gas storage system through a second gas path. The gas paths between the sample cylinder, the reference cylinder, and the terminal operation and gas storage system are all controlled by independent electrically controlled gas valves, which individually control the intake and exhaust functions of each unit.

3. The rock wave velocity dynamic monitoring system for simulating changes in gas content of source rocks according to claim 2, characterized in that, The ultrasonic pulse penetration device is connected to the spring coupling device and the conductive sheet. The spring coupling device tightly couples the ultrasonic pulse device to the top of the core sample, ensuring the accuracy of rock wave velocity measurement.

4. The rock wave velocity dynamic monitoring system for simulating changes in gas content of source rocks according to claim 2, characterized in that, The ultrasonic pulse penetration device includes an ultrasonic pulser, a conductive buffer pad, an air inlet, a connecting circuit, a rock sample coupling top plate, and a pulser latch. The ultrasonic receiving device includes an ultrasonic receiver and a rock sample coupling bottom plate. The ultrasonic pulser is fixed to the rock sample coupling top plate via the pulser latch. The rock sample coupling top plate is connected to the sample cylinder cover plate via a spring coupling device, and the relative position of the coupling top plate inside the cylinder is controlled by the spring coupling device to ensure that the coupling top plate is in close contact with the top of the rock sample. The coupling bottom plate is fixed to the bottom of the sample cylinder to ensure that it is in close contact with the bottom of the rock sample.

5. The rock wave velocity dynamic monitoring system for simulating changes in gas content of source rocks according to claim 2, characterized in that, Each branch gas path of the reference cylinder and sample cylinder is equipped with a gas pressure sensor to monitor the gas pressure changes of different units in real time.

6. The rock wave velocity dynamic monitoring system for simulating changes in gas content of source rocks according to claim 1, characterized in that, The terminal operation and gas storage system has data display and gas storage functions. The terminal operating system is connected to the gas pressure sensor and ultrasonic pulse penetration device of each unit through the circuit to ensure the real-time recovery and display of rock wave velocity and gas pressure monitoring data. The gas storage system is connected to the gas supply system through the first gas path for temporary storage and mixing of gas. At the same time, it is connected to the rock wave velocity and desorbed gas joint monitoring system through the second gas path for regulating gas pressure and distributing it to each independent unit.

7. The rock wave velocity dynamic monitoring system for simulating changes in gas content of source rocks according to claim 1, characterized in that, The gas supply system includes three independent gas tanks, which can be filled with different components of gas according to experimental requirements, and each gas tank is connected to an independent pressure gauge.

8. The rock wave velocity dynamic monitoring system for simulating changes in gas content of source rocks according to claim 1, characterized in that, The desorption gas recovery system is connected to the sample cylinder through a unit gas path. It is used to temporarily store the desorption gas and regulate the gas pressure in the sample cylinder, while avoiding the direct discharge of desorption gas, which could cause safety hazards and environmental pollution.

9. The rock wave velocity dynamic monitoring system for simulating changes in gas content of source rocks according to claim 1, characterized in that, The status display includes a gas pressure sensor status light and an ultrasonic pulse device status light group. It is connected to the ultrasonic pulse penetration device, gas pressure sensor, terminal operation and gas storage system through circuitry to monitor the working status of the ultrasonic pulse penetration device and the gas pressure sensor in real time.

10. A dynamic monitoring system for rock wave velocity to simulate changes in gas content of source rocks according to claim 1, characterized in that, The constant temperature system includes a top-open heating chamber and methyl silicone oil, used for temperature control and insulation during the experiment.

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