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

Abstract

The present application belongs to the technical field of rock wave velocity monitoring, and particularly relates to a rock wave velocity dynamic monitoring test system for simulating gas content change of source rock, comprising: a rock wave velocity and desorbed gas combined monitoring system, a gas chamber for placing a core column sample is arranged in the rock wave velocity and desorbed gas combined monitoring system, the gas chamber has a gas inlet end and a gas outlet end, and the gas pressure in the gas chamber is adjustable; a desorbed gas recovery system, the number of the desorbed gas recovery system is matched with that of the rock wave velocity and desorbed gas combined monitoring system, the gas inlet end of the desorbed gas recovery system is communicated with the gas outlet end of the rock wave velocity and desorbed gas combined monitoring system, and the desorbed gas recovery system is used for recovering desorbed gas; a constant temperature system, the rock wave velocity and desorbed gas combined monitoring system and the desorbed gas recovery system are arranged in the constant temperature system; the constant temperature system is used for providing a temperature environment required by the rock wave velocity and desorbed gas combined monitoring system; and a gas supply control system, connected with the gas inlet end of the rock wave velocity and desorbed gas combined monitoring system, used for supplying gas and detecting the gas pressure of the gas chamber.

Description

Technical Field

[0001] This invention belongs to the field of rock wave velocity monitoring technology, and in particular relates to a dynamic monitoring test system for rock wave velocity that simulates changes in the gas content of source rocks. Background Technology

[0002] Rock wave velocity is a very important kinematic characteristic parameter in the field of seismic exploration. Precise rock wave velocity is required for detailed geological and geophysical modeling and stratigraphic lithology interpretation.

[0003] While existing equipment effectively simulates the characteristics of rock wave velocity variations at different burial depths, in actual oil and gas production, the thickness and depth of the reservoir we are concerned with are often constant. However, as oil and gas are produced, the hydrocarbon gas content in the reservoir exhibits a non-linear decreasing trend. When gas escapes from the rock pores, according to the Wyllie equation, 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 at different gas content stages of oil and gas reservoirs.

[0004] 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 are produced, the decrease in reservoir oil and gas content leads to changes in rock wave velocity, which affects the accuracy of geophysical modeling and stratigraphic lithology interpretation in seismic exploration. Therefore, we propose a dynamic monitoring system for rock wave velocity that simulates changes in source rock gas content. This experimental method reveals the trend of rock wave velocity variation with oil and gas content, providing important 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

[0005] The purpose of this invention is to provide a dynamic monitoring test system for rock wave velocity that simulates changes in the gas content of source rocks, in order to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A dynamic monitoring test system for rock wave velocity to simulate changes in the gas content of source rocks includes:

[0008] At least one rock wave velocity and desorbed gas combined monitoring system, wherein the rock wave velocity and desorbed gas combined monitoring system is provided with a gas chamber for placing a core sample, the gas chamber having an inlet end and an outlet end, and the gas pressure inside the gas chamber is adjustable;

[0009] A desorbed gas recovery system matched with the rock wave velocity and desorbed gas combined monitoring system, an air inlet end of the desorbed gas recovery system being communicated with an air outlet end of the rock wave velocity and desorbed gas combined monitoring system, for recovering desorbed gas;

[0010] A constant temperature system, the rock wave velocity and desorbed gas combined monitoring system and the desorbed gas recovery system being arranged in the constant temperature system; the constant temperature system being used for providing a temperature environment required by the rock wave velocity and desorbed gas combined monitoring system;

[0011] A gas supply control system connected with an air inlet end of the rock wave velocity and desorbed gas combined monitoring system, for supplying gas and detecting the air chamber air pressure.

[0012] Optionally, the rock wave velocity and desorbed gas combined monitoring system comprises:

[0013] A high-pressure-resistant heat-insulating outer cylinder, a sample chamber being arranged on the high-pressure-resistant heat-insulating outer cylinder, the sample chamber being used for placing a core sample;

[0014] A wave velocity measuring part arranged in the sample chamber, for testing the wave velocity of the core sample;

[0015] An air pressure balancing part arranged on one side of the high-pressure-resistant heat-insulating outer cylinder, an air inlet end of the air pressure balancing part being communicated with an air outlet end of the gas supply control system, an air outlet end of the air pressure balancing part being communicated with an air inlet end of the sample chamber; an air outlet end of the sample chamber being communicated with an air inlet end of the desorbed gas recovery system; an electric control valve for controlling the opening and closing of a pipeline being arranged between the air outlet end of the air pressure balancing part and the air inlet end of the sample chamber; an electric control valve for controlling the opening and closing of a pipeline being arranged between the air outlet end of the sample chamber and the air inlet end of the desorbed gas recovery system; a gas pressure sensor being connected in parallel with the air outlet end of the sample chamber, the gas pressure sensor being electrically connected with the gas supply control system;

[0016] The gas supply control system collects the air pressure data of the air pressure balancing part and the sample chamber, and collects the wave velocity data of the wave velocity measuring part.

[0017] Optionally, the air pressure balancing part comprises a reference cylinder, an air inlet end of the reference cylinder being communicated with the gas supply control system, an air outlet end of the reference cylinder being communicated with the sample chamber, another gas pressure sensor being connected in parallel with the air outlet end of the reference cylinder, the gas pressure sensor being electrically connected with the gas supply control system.

[0018] Optionally, the wave velocity measuring part comprises:

[0019] An ultrasonic pulse penetration device arranged on the top of the sample chamber;

[0020] An ultrasonic receiving device is arranged at the bottom of the sample chamber;

[0021] A core column sample is arranged between the ultrasonic pulse penetration device and the ultrasonic receiving device;

[0022] The ultrasonic receiving device is signal connected with the gas supply control system.

[0023] Optionally, the ultrasonic pulse penetration device comprises:

[0024] A core column sample coupling top plate is arranged at the bottom of the core column sample coupling top plate, and the top of the core column sample coupling top plate is provided with a plurality of gas inlets which are equidistantly arranged in the circumferential direction;

[0025] An ultrasonic pulser is arranged at the top of the core column sample coupling top plate, and the ultrasonic pulser is electrically connected with a conductive cushion through a connecting circuit, the conductive cushion is arranged between two adjacent gas inlets, and the conductive cushion is fixed to the top of the core column sample coupling top plate;

[0026] A conductive elastic part is fixed to the bottom end of the conductive cushion, and the top end of the conductive elastic part is connected with the top of the sample chamber, and the conductive elastic part is used for connecting with a power supply wire.

[0027] Optionally, the conductive elastic part comprises a spring, the bottom end of the spring is fixed to the conductive cushion, the top end of the spring is fixed with a conductive sheet, the conductive sheet is embedded in the inner wall of the top of the sample chamber, and the conductive sheet is electrically connected with a power supply.

[0028] Optionally, the ultrasonic receiving device comprises:

[0029] A core column sample coupling bottom plate is fixed to the bottom of the sample chamber;

[0030] An ultrasonic receiver is arranged at the top of the core column sample coupling bottom plate, and the ultrasonic receiver is signal connected with the gas supply control system.

[0031] Optionally, the gas supply control system comprises:

[0032] A terminal operation and gas storage system is connected with the gas outlet of the gas supply system, the gas outlet of the terminal operation and gas storage system is connected with the gas inlet of the reference cylinder, and the terminal operation and gas storage system is used for controlling gas supply and feeding back gas pressure and wave speed data.

[0033] Optionally, the terminal operation and gas storage system comprises:

[0034] A power supply circuit is used for electric energy supply, and is electrically connected with the gas pressure sensor and the conductive sheet;

[0035] A state display is electrically connected with the conductive sheet and the gas pressure sensor, and is used for displaying the power supply state of the gas pressure sensor and the ultrasonic pulser.

[0036] A data processing display device is electrically connected with the gas pressure sensor, and is used for displaying the gas pressure in the sample chamber and the reference cylinder.

[0037] A total gas path pressure gauge is communicated with the gas supply system, and is used for displaying the total input gas pressure.

[0038] An electric control switch is used for controlling the start and stop of the device, and controlling the opening and closing of the electric control valve and the start and stop of the ultrasonic pulser.

[0039] Optionally, the gas supply system comprises:

[0040] A plurality of gas storage tanks are provided, and the plurality of gas storage tanks respectively store different gas sources.

[0041] Pressure gauges are arranged in parallel at the gas outlet ends of the corresponding gas storage tanks, and are used for monitoring the gas outlet pressure of the corresponding gas storage tanks.

[0042] Compared with the prior art, the present application has the following advantages and technical effects:

[0043] In use, the rock wave velocity and desorbed gas combined monitoring system is arranged in a constant temperature system, the constant temperature system provides an experimental environment at different temperatures, and the gas supply control system provides desorbed gas for the rock wave velocity and desorbed gas combined monitoring system, the gas supply control system provides an experimental environment at different gas pressures, and the above arrangement can realize the combined determination experiment of the gas desorption of the source rock and the rock wave velocity under different temperatures and different gas pressures. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only illustrate some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0045] Figure 1 Structure diagram of the present application;

[0046] Figure 2 Structure diagram of the rock wave velocity and desorbed gas combined monitoring system of the present application;

[0047] Figure 3 Top view of the ultrasonic pulse penetration device of the present application;

[0048] Figure 4 Top view of the ultrasonic receiving device of the present application;

[0049] Figure 5 Installation structure diagram of the ultrasonic pulse penetration device and the ultrasonic receiving device of the present application;

[0050] Among them, 1, terminal operation and gas storage system; 11, data processing display device; 12, total gas path pressure gauge; 13, electric control switch; 2, gas supply system; 21, pressure gauge; 22, gas storage tank; 3, rock wave velocity and desorbed gas combined monitoring system; 31, high-pressure-resistant heat-insulating outer cylinder; 32, sample chamber; 33, ultrasonic pulse penetration device; 331, ultrasonic pulser; 332, conductive cushion pad; 333, gas inlet; 334, connecting circuit; 335, core column sample coupling top plate; 336, pulser tenon; 34, ultrasonic receiving device; 341, ultrasonic receiver; 342, core column sample coupling bottom plate; 35, conductive sheet; 36, spring; 37, reference cylinder; 38, gas pressure sensor; 4, state display; 41, gas pressure sensor state light; 42, ultrasonic pulse device state light group; 5, desorbed gas recovery system; 6, constant temperature system. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, and not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0052] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0053] Referring to Figures 1 to 5 The application discloses a rock wave velocity dynamic monitoring test system for simulating gas content change of a hydrocarbon source rock, comprising:

[0054] At least one rock wave velocity and desorbed gas combined monitoring system 3 is internally provided with a gas chamber for placing a core column sample, the gas chamber has a gas inlet end and a gas outlet end, and the gas pressure in the gas chamber is adjustable;

[0055] A desorbed gas recovery system 5 is matched in number with the rock wave velocity and desorbed gas combined monitoring system 3, the gas inlet end of the desorbed gas recovery system 5 is communicated with the gas outlet end of the rock wave velocity and desorbed gas combined monitoring system 3, and the desorbed gas recovery system 5 is used for recovering desorbed gas;

[0056] A constant temperature system 6 is internally provided with the rock wave velocity and desorbed gas combined monitoring system 3 and the desorbed gas recovery system 5; the constant temperature system 6 is used for providing a temperature environment required by the rock wave velocity and desorbed gas combined monitoring system 3;

[0057] A gas supply control system is connected with the gas inlet end of the rock wave velocity and desorbed gas combined monitoring system 3 and is used for supplying gas and detecting the gas pressure of the gas chamber.

[0058] In use, the rock wave velocity and desorbed gas combined monitoring system 3 is arranged in the constant temperature system 6, a different temperature experimental environment is provided by the constant temperature system 6, the desorbed gas is provided for the rock wave velocity and desorbed gas combined monitoring system 3 by the gas supply control system, a different gas pressure experimental environment is provided by the gas supply control system, and the above arrangement can realize the combined determination experiment of the desorbed gas of the hydrocarbon source rock and the rock wave velocity under different temperatures and different gas pressures. The application can simulate the rock wave velocity dynamic monitoring experiment of the hydrocarbon source rock with different gas content changes, can simulate the desorbed gas rate of the hydrocarbon source rock in the unconventional natural gas production engineering and the dynamic data determination of the change trend of the rock wave velocity of the hydrocarbon source rock with the desorbed gas content in different production stages by carrying out the isothermal desorption experiment under different temperatures, different gas pressures and different lithology multi-factor coupling conditions. The experimental device is simple, easy to operate, has good use effect and is easy to popularize.

[0059] The constant temperature system 6 is composed of a top open type heating box body and methyl silicone oil, the rock wave velocity and desorbed gas combined monitoring system 3 and the desorbed gas recovery system 5 are immersed in the methyl silicone oil during the desorption and rock wave velocity determination experiment, and the temperature control and temperature preservation functions can be realized.

[0060] As an optional implementation manner, the rock wave velocity and desorbed gas combined monitoring system 3 comprises:

[0061] A high-pressure-resistant heat preservation outer cylinder 31 is internally provided with a sample chamber 32, the sample chamber 32 is used for placing the core column sample;

[0062] A wave velocity measuring unit is arranged in the sample chamber 32 to test the wave velocity of the core sample;

[0063] A gas pressure balancing unit is arranged on one side of the high-pressure resistant heat-insulating outer cylinder 31. The gas inlet end of the gas pressure balancing unit is connected with the gas outlet end of the gas supply control system, and the gas outlet end of the gas pressure balancing unit is connected with the gas inlet end of the sample chamber 32. The gas outlet end of the sample chamber 32 is connected with the gas inlet end of the desorbed gas recovery system 5. An electrically controlled valve for controlling the opening and closing of the pipeline is arranged between the gas outlet end of the gas pressure balancing unit and the gas inlet end of the sample chamber 32. An electrically controlled valve for controlling the opening and closing of the pipeline is arranged between the gas outlet end of the sample chamber 32 and the gas inlet end of the desorbed gas recovery system 5. The gas outlet end of the sample chamber 32 is connected in parallel with a gas pressure sensor 38, and the gas pressure sensor 38 is electrically connected with the gas supply control system.

[0064] The gas supply control system collects the gas pressure data of the gas pressure balancing unit and the sample chamber 32, and collects the wave velocity data of the wave velocity measuring unit.

[0065] As an optional embodiment, the gas pressure balancing unit comprises a reference cylinder 37. The gas inlet end of the reference cylinder 37 is connected with the gas supply control system, and the gas outlet end of the reference cylinder 37 is connected with the sample chamber 32. The gas outlet end of the reference cylinder 37 is connected in parallel with another gas pressure sensor 38, and the gas pressure sensor 38 is electrically connected with the gas supply control system.

[0066] As an optional embodiment, the wave velocity measuring unit comprises:

[0067] An ultrasonic pulse penetration device 33 is arranged on the top of the sample chamber 32.

[0068] An ultrasonic receiving device 34 is arranged on the bottom of the sample chamber 32.

[0069] The core sample is arranged between the ultrasonic pulse penetration device 33 and the ultrasonic receiving device 34.

[0070] The ultrasonic receiving device 34 is signal connected with the gas supply control system.

[0071] As an optional embodiment, the ultrasonic pulse penetration device 33 comprises:

[0072] A core sample coupling top plate 335 is arranged on the top of the ultrasonic pulse penetration device 33. The bottom of the core sample coupling top plate 335 is in contact with the top of the core sample. A plurality of gas inlets 333 are arranged on the top of the core sample coupling top plate 335 in equal intervals in the circumferential direction.

[0073] The ultrasonic pulser 331 is axially connected to the top of the core sample coupling top plate 335; the ultrasonic pulser 331 is electrically connected to the conductive cushion 332 through the connecting circuit 334, the conductive cushion 332 is arranged between two adjacent air inlets 333, and the conductive cushion 332 is fixed to the top of the core sample coupling top plate 335;

[0074] The conductive elastic part is fixed to the bottom end of the conductive cushion 332, and the top end of the conductive elastic part is connected to the top of the sample chamber 32; the conductive elastic part is used for connecting the power supply wire.

[0075] As an optional implementation, the conductive elastic part includes a spring 36, the bottom end of the spring 36 is fixed to the conductive cushion 332, and the top end of the spring 36 is fixed to a conductive sheet 35, the conductive sheet 35 is embedded in the inner wall of the top of the sample chamber 32, and the conductive sheet 35 is electrically connected to the power supply.

[0076] As an optional implementation, the ultrasonic receiving device 34 includes:

[0077] The core sample coupling bottom plate 342 is fixed to the bottom of the sample chamber 32;

[0078] The ultrasonic receiver 341 is axially connected to the top of the core sample coupling bottom plate 342, and the ultrasonic receiver 341 is signal-connected to the gas supply control system.

[0079] The rock wave velocity and desorbed gas combined monitoring system 3 includes a high-pressure-resistant heat-insulating outer cylinder 31, a sample chamber 32, an ultrasonic pulse penetration device 33, an ultrasonic receiving device 34, a conductive sheet 35, a spring 36, a reference cylinder 37, and a gas pressure sensor 38; the gas pressure sensor 38 is connected to the end of each branch gas path of the reference cylinder 37 and the sample chamber 32, and is used for monitoring the gas pressure change of different units in real time; the ultrasonic pulse penetration device 33 is connected to the spring 36 and the conductive sheet 35, and the spring 36 can tightly couple the ultrasonic pulse penetration device 33 to the top of the core sample, thereby ensuring the accuracy of rock wave velocity measurement.

[0080] The ultrasonic pulse penetration device 33 includes an ultrasonic pulser 331, a conductive cushion 332, an air inlet 333, a connecting circuit 334, a core sample coupling top plate 335, and a pulser dowel 336; the ultrasonic receiving device 34 includes an ultrasonic receiver 341 and a core sample coupling bottom plate 342.

[0081] The ultrasonic pulser 331 is fixed to the core sample coupling top plate 335 through the pulser tenon 336, the coupling top plate is connected with the sample chamber 32 through the spring 36, and the relative position of the core sample coupling top plate 335 in the cylinder is controlled through the spring 36, so that the core sample coupling top plate 335 is tightly connected with the top of the core sample. The core sample coupling bottom plate 342 is fixed to the bottom of the sample chamber, and is tightly connected with the bottom of the core sample.

[0082] The conductive buffer pad 332 on the core sample coupling top plate 335 can reduce the influence of the instantaneous release of spring kinetic energy on the coupling top plate, avoid the longitudinal displacement of the coupling top plate, and reduce the experimental error; the four circular gas inlets 333 of the coupling top plate can ensure the smoothness of the gas path when the coupling top plate is tightly connected with the core sample.

[0083] The desorbed gas recovery system 5 is connected with the sample chamber 32 through the unit gas path, can temporarily store the desorbed gas of the source rock, is finally connected to the total gas path, and directly discharges the desorbed waste gas after the experiment is completed, or is connected with the gas chromatograph to carry out further desorbed gas component analysis.

[0084] As an optional implementation, the gas supply control system comprises:

[0085] The terminal operation and gas storage system 1 is connected with the gas outlet end of the gas supply system 2, and the gas outlet end of the terminal operation and gas storage system 1 is connected with the gas inlet end of the reference cylinder 37. The terminal operation and gas storage system 1 is used for controlling the gas supply and feeding back the gas pressure and wave velocity data.

[0086] As an optional implementation, the terminal operation and gas storage system 1 comprises:

[0087] The power supply line is used for electric energy supply, and is electrically connected with the gas pressure sensor 38 and the conductive sheet 35;

[0088] The state display 4 is electrically connected with the conductive sheet 35 and the gas pressure sensor 38, and is used for displaying the power supply state of the gas pressure sensor 38 and the ultrasonic pulser 331;

[0089] The data processing and display device 11 is electrically connected with the gas pressure sensor 38, and is used for displaying the gas pressure in the sample chamber 32 and the reference cylinder 37. The data processing and display device 11 is signal connected with the ultrasonic receiver 341, and is used for displaying the wave velocity data.

[0090] The total gas path pressure gauge 12 is connected with the gas supply system 2, and is used for displaying the total input gas pressure.

[0091] The electric control switch 13 is used for controlling the start and stop of the device, and controlling the opening and closing of the electric control valve and the start and stop of the ultrasonic pulser 331.

[0092] As an optional implementation, the gas supply system 2 comprises:

[0093] The gas storage tanks 22 are provided in plurality, and the plurality of gas storage tanks 22 respectively store different gas sources;

[0094] The pressure gauges 21 are arranged in parallel at the gas outlet ends of the corresponding gas storage tanks 22, and are used for monitoring the gas outlet pressure of the corresponding gas storage tanks 22; the gas outlet ends of the plurality of gas storage tanks 22 are communicated with the gas inlet end of the reference cylinder 37 through the same pipeline, and the total gas circuit pressure gauge 12 is arranged in parallel on the pipeline.

[0095] The total circuit is responsible for connecting the terminal operation and gas storage system 1, the ultrasonic pulse penetration device 33 and the gas pressure sensor 38, and can transmit the monitored gas pressure and rock wave speed data to the terminal operation and gas storage system 1 and display the data in real time on the data processing and display device 11, so as to facilitate the experimental operators to carry out data collation and analysis.

[0096] The gas supply system 2 comprises three independent gas storage tanks 22, each of which is independently connected with a pressure gauge 21, and can flexibly perform content proportioning of experimental gas. In actual use, in a conventional experiment, three independent gas storage tanks respectively store 99.9% high-purity gas of three different components, i.e., low-pressure helium (3Mpa), high-pressure methane (12Mpa) and high-pressure carbon dioxide (12Mpa), the low-pressure helium is an inert gas and is not adsorbed by the hydrocarbon source rock pores, and can be used for free space volume determination of the reference cylinder and the sample chamber; the high-pressure methane and carbon dioxide can be mixed in the terminal operation and gas storage system 1, and the content proportioning of the mixed gas can be flexibly adjusted according to the experimental requirements and the types of core samples. At the same time, the terminal operation and gas storage system 1 is provided with a total gas circuit pressure gauge 12 and an electric control switch 13, and can adjust and control the gas pressure finally delivered to each experimental unit.

[0097] The state display 4 comprises a gas pressure sensor state lamp 41 and an ultrasonic pulse device state lamp group 42, and is connected with the ultrasonic pulse penetration device 33, the gas pressure sensor 38 and the terminal operation and gas storage system 1 through a circuit, and can monitor the working states of the ultrasonic pulse penetration device 33 and the gas pressure sensor 38 in real time, so as to ensure normal operation of the instrument and effective recovery of data.

[0098] The working principle and process of the present application are as follows:

[0099] When the experiment is carried out, first, the volume parameters of the core column sample are measured and recorded, the top cover of the sample chamber 32 is opened, then the core column sample is vertically placed in the sample chamber 32, and the bottom of the core column sample is tightly connected with the core column sample coupling bottom plate 342; the top cover of the sample chamber 32 is tightly pressed, and the core column sample coupling top plate 335 is tightly connected with the top of the core column sample under the action of the spring 36. After the core sample is placed, the rock wave speed and desorbed gas combined monitoring system 3 and the desorbed gas recovery system 5 are placed in the constant temperature system 6.

[0100] The ultrasonic pulse penetration device 33 is opened, and the rock wave speed of the core column sample is continuously monitored until the experiment is completed. The time taken by the ultrasonic wave to pass through the core column sample is measured, the length of the core column is divided by the time, the elastic wave speed of the ultrasonic wave passing through the experimental sample is obtained (formula 2, 3), and finally the rock wave speed determined is viewed in real time through the data processing display device 11,

[0101] Vp = L / tp (2)

[0102] Vs = L / ts (3)

[0103] In the formula, Vp is the rock longitudinal wave speed, Vs is the rock transverse wave speed, L is the length of the core column sample, and tp and ts respectively represent the time taken by the longitudinal wave and the transverse wave to pass through the rock sample.

[0104] The experimental temperature is set through the constant temperature system 6, after the system temperature is stable, the helium gas tank of the gas supply system 2 is opened, and the pressure is adjusted to 0.5 MPa, the first gas path and the second gas path electric control valves are opened, the helium gas is filled into the terminal operation and gas storage system 1 and the reference cylinder 37, the gas pressure reaches 0.5 MPa, and the gas pressure values of the reference cylinder 37 and the sample chamber 32 at this time are recorded; then the first gas path and the second gas path electric control valves are closed, the electric control valve of the unit gas path between the reference cylinder 37 and the sample chamber 32 is opened, the reference cylinder 37 and the sample chamber 32 are kept in communication, and the system is left for 20 minutes. After the gas pressure of the reference cylinder 37 and the sample chamber 32 is stable and balanced, the gas pressure values of the two cylinders at this time are recorded. The above steps are repeated for 3-5 times, the average value of the measured gas pressure before and after balancing is taken, and the free space volume of the sample chamber 32 is calculated by substituting it into the corresponding formula. After the free space volume is measured, the first gas path electric control valve is closed, and all the second gas path and unit gas path electric control valves are opened, and the helium gas is completely discharged from the experimental device.

[0105] Open the methane gas tank, carbon dioxide gas tank of the gas supply system 2, and adjust the pressure to obtain the required mixed gas ratio (in addition to the helium gas tank, the other two gases can be flexibly replaced according to the experimental requirements), open the first gas path, the second gas path electric control valve, fill the experimental gas into the terminal operation and gas storage system 1, the reference cylinder 37, make the gas pressure reach 12MPa, record the gas pressure, rock wave velocity value of the reference cylinder 37, the sample chamber 32 at this time; then close the first gas path, the second gas path electric control valve, open the electric control valve of the unit gas path between the reference cylinder 37, the sample chamber 32, keep the reference cylinder 37 and the sample chamber 32 in communication, stand for 12 hours, until the core sample in the sample chamber 32 reaches the adsorption saturation state, record the gas pressure, rock wave velocity value of the core sample reaching the adsorption saturation state.

[0106] After the core sample is saturated with adsorbed gas, the electric control valve of the unit gas path between the reference cylinder 37, the sample chamber 32 is closed, the desorption gas pressure gradient designed in the experiment is taken as the threshold value (for example: 10MPa, 8MPa, 6MPa, 4MPa, 2MPa, 0MPa), the electric control valve of the unit gas path between the sample chamber 32, the desorption gas recovery system 5 is repeatedly opened and closed, so that the gas pressure of the sample chamber 32 is reduced to the designed gas pressure gradient threshold value, and is kept for 12 hours, until the negative pressure desorption is completed, the gas pressure, rock wave velocity value of the core sample at the desorption pressure point is recorded. Repeat the above steps until the lowest set pressure 0Mpa, ensure that the core sample adsorbed gas has been completely desorbed, record the gas pressure, rock wave velocity value of the core sample after desorption is completed, and the gas content of the core sample under different desorption pressures is calculated through the corresponding formula, and finally the terminal operation and gas storage system 1 is used to represent that the rock wave velocity of the core sample under different desorption pressures changes dynamically with the gas content.

[0107] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application.

[0108] The above-described embodiments are only descriptions of the preferred modes of the present application, and do not limit the scope of the present application, and various modifications and improvements to the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope determined by the claims of the present application.

Claims

1. A rock wave velocity dynamic monitoring test system for simulating gas content change of a hydrocarbon source rock, characterized in that, The application relates to a rock wave velocity and desorbed gas combined monitoring system. The application comprises: at least one rock wave velocity and desorbed gas combined monitoring system (3) which is internally provided with a gas chamber for placing a core column sample, the gas chamber has a gas inlet end and a gas outlet end, and the gas pressure in the gas chamber can be adjusted; a desorbed gas recovery system (5) which is matched with the rock wave velocity and desorbed gas combined monitoring system (3), the gas inlet end of the desorbed gas recovery system (5) is communicated with the gas outlet end of the rock wave velocity and desorbed gas combined monitoring system (3), and the desorbed gas recovery system (5) is used for recovering desorbed gas; a constant temperature system (6) in which the rock wave velocity and desorbed gas combined monitoring system (3) and the desorbed gas recovery system (5) are arranged, and the constant temperature system (6) is used for providing a temperature environment required by the rock wave velocity and desorbed gas combined monitoring system (3); a gas supply control system which is connected with the gas inlet end of the rock wave velocity and desorbed gas combined monitoring system (3) and is used for supplying gas and detecting the gas pressure of the gas chamber; the rock wave velocity and desorbed gas combined monitoring system (3) comprises: a high-pressure-resistant heat-insulating outer cylinder (31) in which a sample chamber (32) is arranged, and the sample chamber (32) is used for placing a core column sample; a wave velocity measuring part which is arranged in the sample chamber (32) and is used for testing the wave velocity of the core column sample; a gas pressure balancing part which is arranged on one side of the high-pressure-resistant heat-insulating outer cylinder (31), the gas inlet end of the gas pressure balancing part is communicated with the gas outlet end of the gas supply control system, the gas outlet end of the gas pressure balancing part is communicated with the gas inlet end of the sample chamber (32), the gas outlet end of the sample chamber (32) is communicated with the gas inlet end of the desorbed gas recovery system (5), an electric control valve for controlling the opening and closing of a pipeline is arranged between the gas outlet end of the gas pressure balancing part and the gas inlet end of the sample chamber (32), an electric control valve for controlling the opening and closing of a pipeline is arranged between the gas outlet end of the sample chamber (32) and the gas inlet end of the desorbed gas recovery system (5), a gas pressure sensor (38) is connected in parallel with the gas outlet end of the sample chamber (32), and the gas pressure sensor (38) is electrically connected with the gas supply control system; the gas supply control system collects the gas pressure data of the gas pressure balancing part and the sample chamber (32) and collects the wave velocity data of the wave velocity measuring part; 2. The rock wave velocity dynamic monitoring test system for simulating the gas content change of hydrocarbon source rock according to claim 1, characterized in that, the gas pressure balancing part comprises a reference cylinder (37), the gas inlet end of the reference cylinder (37) is communicated with the gas supply control system, the gas outlet end of the reference cylinder (37) is communicated with the sample chamber (32), another gas pressure sensor (38) is connected in parallel with the gas outlet end of the reference cylinder (37), and the gas pressure sensor (38) is electrically connected with the gas supply control system. the wave velocity measuring part comprises: an ultrasonic wave pulse penetration device (33) which is arranged on the top of the sample chamber (32); an ultrasonic wave receiving device (34) which is arranged on the bottom of the sample chamber (32); a core column sample is arranged between the ultrasonic wave pulse penetration device (33) and the ultrasonic wave receiving device (34); the ultrasonic wave receiving device (34) is signal-connected with the gas supply control system.

3. The rock wave velocity dynamic monitoring test system for simulating the gas content change of hydrocarbon source rock according to claim 2, characterized in that, The ultrasonic pulse penetrating device (33) comprises: A core column sample coupling top plate (335) is arranged at the bottom of the core column sample and is in contact with the top of the core column sample; a plurality of air inlets (333) are arranged on the top of the core column sample coupling top plate (335) in equal intervals in the circumferential direction; An ultrasonic pulser (331) is arranged on the top of the core column sample coupling top plate (335); the ultrasonic pulser (331) is electrically connected with a conductive cushion (332) through a connecting circuit (334), the conductive cushion (332) is arranged between two adjacent air inlets (333), and the conductive cushion (332) is fixed on the top of the core column sample coupling top plate (335); A conductive elastic part is fixedly connected with the conductive cushion (332) at the bottom end, the top end of the conductive elastic part is connected with the top of the sample chamber (32), and the conductive elastic part is used for being connected with a power supply wire.

4. The rock wave velocity dynamic monitoring test system for simulating the change of hydrocarbon source rock gas content according to claim 3, characterized in that: The conductive elastic part comprises a spring (36), the bottom end of the spring (36) is fixedly connected with the conductive cushion (332), and the top end of the spring (36) is fixedly connected with a conductive sheet (35) which is embedded in the inner wall of the top of the sample chamber (32); and the conductive sheet (35) is electrically connected with a power supply.

5. The rock wave velocity dynamic monitoring test system for simulating the change of hydrocarbon source rock gas content according to claim 4, characterized in that, The ultrasonic receiving device (34) comprises: A core column sample coupling bottom plate (342) is fixedly connected with the bottom of the sample chamber (32); An ultrasonic receiver (341) is arranged on the top of the core column sample coupling bottom plate (342), and the ultrasonic receiver (341) is signal-connected with the gas supply control system.

6. The rock wave velocity dynamic monitoring test system for simulating the change of hydrocarbon source rock gas content according to claim 5, characterized in that, The gas supply control system comprises: A terminal operation and gas storage system (1) is connected with the outlet of a gas supply system (2) at the gas inlet end, the outlet of the terminal operation and gas storage system (1) is connected with the gas inlet end of the reference cylinder (37), and the terminal operation and gas storage system (1) is used for controlling gas supply and feeding back gas pressure and wave velocity data.

7. The rock wave velocity dynamic monitoring test system for simulating the change of hydrocarbon source rock gas content according to claim 6, characterized in that, The terminal operation and gas storage system (1) comprises: A power supply circuit is used for electric energy supply and is electrically connected with the gas pressure sensor (38) and the conductive sheet (35); A state display (4) is electrically connected with the conductive sheet (35) and the gas pressure sensor (38) and is used for displaying the power supply state of the gas pressure sensor (38) and the ultrasonic pulser (331); A data processing and display device (11) is electrically connected with the gas pressure sensor (38) and is used for displaying the gas pressure in the sample chamber (32) and the reference cylinder (37); the data processing and display device (11) is signal-connected with the ultrasonic receiver (341) and is used for displaying wave velocity data; A total gas path pressure gauge (12) is connected with the gas supply system (2) and is used for displaying total input gas pressure; An electric control switch (13) is used for controlling the start and stop of the device, the opening and closing of the electric control valve and the start and stop of the ultrasonic pulser (331).

8. The rock wave velocity dynamic monitoring test system for simulating the change of hydrocarbon source rock gas content according to claim 7, characterized in that, The gas supply system (2) comprises: A plurality of gas storage tanks (22) are provided, and each of the plurality of gas storage tanks (22) stores different gas sources; A pressure gauge (21) is provided in parallel at the gas outlet end of the corresponding gas storage tank (22) to monitor the gas outlet pressure of the corresponding gas storage tank (22), and the gas outlet ends of the plurality of gas storage tanks (22) are communicated with the gas inlet end of the reference cylinder (37) through the same pipeline, and the total gas path pressure gauge (12) is provided in parallel on the pipeline.

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