An apparatus and method for simulating a rock acoustics testing device in a CO2 geological storage environment

Abstract

The application relates to the field of rock physical property detection, and discloses a rock acoustic testing device and method for simulating a CO2 geological storage environment, which comprises a pressure chamber, the outer surface of the pressure chamber is coupled with a detection unit and a pressurizing unit, and the detection unit and the pressurizing unit are electrically connected with a preset control unit; the preset rock sample to be detected is detected through the detection unit, and the detection result is fed back to the control unit; the application is characterized in that a special clamping device and laser positioning are used to accurately fix and adjust the plunger sample, rock acoustic testing under the simulated CO2 geological storage environment can be carried out, the response characteristics of rock acoustic parameters (P and S wave velocities) under different CO2 phase states and pore pressures can be explored, the feasibility and risks of CO2 storage can be better evaluated, meanwhile, the development of CO2 geological storage monitoring technology by using earthquakes in domestic related CCUS projects can be supported, and basic data and basis for the technology are provided.

Description

Technical Field

[0001] This invention relates to the field of rock physical property testing, and in particular to an acoustic testing device and method for rocks in a simulated CO2 geological storage environment. Background Technology

[0002] Rock acoustic testing refers to a testing method that uses the characteristics and laws of sound wave propagation inside rocks to detect and analyze the physical and mechanical properties, rock structure, and internal cracks of rocks.

[0003] Conventional rock acoustic testing is generally conducted at room temperature. However, when testing and studying rocks in underground environments, the temperature, pressure, and other conditions of the underground environment are different from those at room temperature. Conventional testing cannot fully simulate the underground environment. For example, when CO2 is trapped underground, the geological environment (temperature and pressure) is variable, which will affect the authenticity and reliability of the test results, and thus affect the accuracy of the test. Summary of the Invention

[0004] To address the above problems, embodiments of the present invention provide a rock acoustic testing device that simulates a CO2 geological storage environment.

[0005] In a first aspect, embodiments of the present invention provide a rock acoustic testing device for simulating a CO2 geological storage environment, including a pressure chamber, wherein a detection unit and a pressurization unit are coupled to the outer surface of the pressure chamber, and the detection unit and the pressurization unit are respectively electrically connected to a preset control unit;

[0006] The detection unit detects the preset rock sample to be tested and feeds back the detection results to the control unit. The control unit controls the pressurization unit to apply a preset pressure value to the pressure chamber based on the detection results. When the pressure value reaches the preset value, the control unit sends an excitation and reception command for the rock sample to be tested to the detection unit and collects the arrival time of the transmitted ultrasonic waveform signal of the rock sample to be tested.

[0007] Furthermore, the outer surface of the pressure chamber is also provided with a heating unit for controlling the temperature inside the pressure chamber to remain constant.

[0008] Furthermore, the pressure chamber is equipped with a sealing sleeve for enclosing the rock sample to be tested, and a CO2 fluid injection unit is provided outside the pressure chamber to maintain the pore pressure of the rock sample to be tested inside the sealing sleeve.

[0009] Furthermore, the sealing sleeve is made of a material resistant to CO2 corrosion.

[0010] Furthermore, the CO2 corrosion-resistant material is made of silicone rubber or Teflon.

[0011] Furthermore, the CO2 injection unit includes a corrosion-resistant constant-speed and constant-pressure pump and a pore fluid cooling system. One end of the corrosion-resistant constant-speed and constant-pressure pump is connected to the pore fluid cooling system, and the other end passes through a pipeline through a pressure chamber and a sealing sleeve into the rock sample to be tested. The other end of the pore fluid cooling system is connected to a CO2 cylinder. The phase of CO2 entering the corrosion-resistant constant-speed and constant-pressure pump is controlled by the pore fluid cooling system, and a preset pore pressure is applied to the rock sample to be tested by the corrosion-resistant constant-speed and constant-pressure pump.

[0012] Furthermore, the pressure chamber is cylindrical to ensure a uniform pressure distribution inside.

[0013] Furthermore, the control unit includes a computer, which includes a signal control port and a signal receiving port. The signal control port is connected to the pressurization unit, and the signal receiving port is connected to the detection unit. The pressurization unit is controlled by the signal control port to apply a preset pressure value to the pressure chamber, and the arrival time of the ultrasonic waveform signal transmitted by the detection unit to the rock sample under test is acquired by the signal receiving port.

[0014] Secondly, embodiments of the present invention provide a method for testing the acoustic properties of rocks in a simulated CO2 geological storage environment, and the specific steps of the testing method are as follows:

[0015] The preset rock sample to be tested is detected by the detection unit;

[0016] The control unit controls the pressurization unit to apply a preset pressure value to the pressure chamber based on the detection results of the detection unit. When the pressure value reaches the preset value and stabilizes at the preset value, the pressurization of the rock sample to be tested is stopped.

[0017] After the pressurization is stopped, the control unit sends a command to the detection unit to excite ultrasonic waves at one end of the preset test rock sample and to receive the ultrasonic longitudinal and transverse wave waveform signals collected after passing through the preset test rock sample.

[0018] After the command is sent, the control unit picks up the initial arrival time of the longitudinal and transverse wave waveforms transmitted through the rock sample to be tested. This time can also be called the arrival time. Based on the preset length L of the sample to be tested and the preset ultrasonic probe zero time, which includes the longitudinal wave zero time t, the control unit then selects the initial arrival time. p0 and transverse wave at zero time t s0 Calculate the longitudinal wave velocity V of rocks in a simulated CO2 geological sequestration environment. p and transverse wave velocity V s :

[0019]

[0020] Where L is the sample length, t1 is the arrival time of the longitudinal wave, and t p0 When the longitudinal wave reaches zero, t2 is when the transverse wave arrives, and t...s0 It is when the transverse wave is at zero.

[0021] Compared with the prior art, the above-mentioned technical solution of the present invention has the following beneficial effects:

[0022] By conducting acoustic tests on rocks in simulated CO2 geological storage environments, we can explore the response characteristics of rock acoustic parameters (P-wave and S-wave velocities) under different CO2 phases, pore pressures, and other conditions. This will help to better assess the feasibility and risks of CO2 storage, and at the same time support the development of seismic monitoring technology for CO2 geological storage in relevant domestic CCUS projects, providing basic data and evidence for these technologies. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a module connection diagram of a rock acoustic testing device for simulating a CO2 geological storage environment in this invention;

[0025] Figure 2 This is a flowchart of a method for simulating the acoustic testing of rocks in a CO2 geological storage environment according to the present invention.

[0026] Figure 3 This is the method used in this invention. Figure 2 The curves of longitudinal and transverse wave velocities of fully CO2-saturated rocks as a function of confining pressure were obtained by using a rock acoustic testing method in a simulated CO2 geological storage environment at a temperature of 45℃ and a pore pressure of 10MPa.

[0027] Figure 4 This is a flowchart of a method for testing the acoustic properties of rocks in a simulated CO2 geological storage environment, as described in this invention.

[0028] In the picture:

[0029] 1. Detection unit;

[0030] 2. Pressure chamber;

[0031] 3. Sealing sleeve;

[0032] 4. Control unit;

[0033] 5. Pressurization unit;

[0034] 6. Heating unit;

[0035] 7. CO2 fluid injection unit. Detailed Implementation

[0036] The present disclosure will be further described below with reference to the embodiments shown in the accompanying drawings.

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] This invention proposes a rock acoustic testing device and method for simulating a CO2 geological storage environment. By conducting rock acoustic tests in a simulated CO2 geological storage environment, the response characteristics of P-wave and S-wave velocities of rock acoustic parameters under different CO2 phases, pore pressures, and other conditions are explored, supporting the development of seismic monitoring technology for CO2 geological storage in relevant domestic CCUS projects.

[0039] Example 1

[0040] Figure 1 An acoustic testing device for simulating a CO2 geological storage environment is provided in this embodiment of the present disclosure, such as... Figure 1 As shown:

[0041] An acoustic testing device for rocks in a simulated CO2 geological storage environment, in this embodiment, includes a pressure chamber 2 for containing a preset rock sample to be tested. The pressure chamber 2 is cylindrical to ensure uniform pressure distribution inside the pressure chamber 2. A detection unit 1 is provided on one side of the pressure chamber 2. The detection unit 1 consists of two sets of ultrasonic probes for exciting and receiving ultrasonic signals. The two sets of ultrasonic probes are respectively in close contact with both ends of the preset rock sample to be tested.

[0042] In this scheme, the cylindrical pressure chamber is closer to the real underground reservoir in shape and size, so it can better simulate the real underground environment and more accurately assess the acoustic characteristics of the carbon dioxide geological storage process.

[0043] Furthermore, cylindrical pressure chambers can be used to control changes in pressure and temperature, which affect the results of acoustic property tests. For example, as pressure increases, the closure of pores inside the rock sample affects the propagation and reflection of sound waves. Therefore, controlling pressure and temperature makes it easier to obtain accurate test results.

[0044] Furthermore, conducting tests in a cylindrical pressure chamber facilitates sampling and processing, eliminates the need for cascaded testing instruments, simplifies the testing process, reduces the possibility of testing errors, and ensures the accuracy of test results.

[0045] In summary, placing the rock sample to be tested in a cylindrical pressure chamber for acoustic testing can more accurately simulate the underground environment, better control pressure and temperature changes, facilitate sampling and processing, and thus improve the reliability of the test results.

[0046] In use, the preset rock sample to be tested is placed in the pressure chamber, and the ultrasonic probe at one end of the detection unit 1 is placed close to one end of the preset rock sample, while the ultrasonic probe at the other end of the detection unit 1 is placed close to the other end of the preset rock sample.

[0047] In this invention, the ultrasonic probe is in close contact with both ends of the rock sample, which can greatly reduce the reflection and refraction of the sound wave signal during propagation, avoid waveform interference and mutual interference, thereby improving the accuracy and reliability of the test data.

[0048] Direct contact between the probe and the rock sample can reduce test errors caused by uneven contact quality between the media, and also reduce the influence of other factors on the test results, thus improving the accuracy of the test.

[0049] The ultrasonic probe is attached to both ends of the rock sample, eliminating the need for other auxiliary devices to clamp and fix the rock sample. This method is simple to operate and also facilitates data acquisition and control.

[0050] In this embodiment, a control unit 4 is provided at one end of the detection unit 1, and the control unit 4 is provided with a computer, which includes a signal control port and a signal receiving port.

[0051] The signal control port is connected to the pressurization unit 5 to apply confining pressure and axial pressure to the pressure chamber 2. The signal receiving port is connected to the detection unit 1 to collect the ultrasonic longitudinal and transverse wave signals transmitted through the preset test rock sample.

[0052] In the equipment used for testing, the computer and control unit, such as the pressurization unit, are connected through a signal control port. The control unit receives test data through a signal input port, and the computer uses its own signal processing and control program to operate and control the equipment in the control unit and collect data.

[0053] Furthermore, the test results are transmitted to the detection unit for processing and analysis through the signal output port. This method makes it easier to control the test and process the data, while improving the accuracy and reliability of the test.

[0054] In this embodiment of the invention, by applying stable confining pressure and axial pressure to the rock sample to be tested in the pressure chamber 2 using the confining pressure pump and axial pressure pump in the pressurization unit 5 in constant pressure mode, the experimental data can be kept in a stable state, and the impact of changes in confining pressure or axial pressure on the experimental results can be reduced.

[0055] Using constant pressure mode allows for more accurate pressure measurement based on the established correspondence between pressure parameters and experimental results, ensuring the stability and reliability of experimental results and avoiding inaccurate data due to excessive measurement errors.

[0056] Using constant pressure mode makes experimental operation more convenient and practical. Since the pressure is fixed, it is easier to stop and start the experimental process, reducing the difficulty of operation and the risk of error.

[0057] In this scheme, the signal receiving port is connected to the detection unit 1 and is used to collect the ultrasonic longitudinal and transverse wave signals transmitted through the preset rock sample to be tested. The existence of the signal receiving port allows the detection unit 1 to fully receive the ultrasonic longitudinal and transverse wave signals transmitted through the preset rock sample to be tested, so as to realize comprehensive ultrasonic detection and obtain complete material properties and damage information.

[0058] By using a signal receiving port to collect ultrasonic signals, wireless data transmission can be achieved, which greatly improves the efficiency and accuracy of experimental data acquisition and provides a strong foundation for optimizing the experimental process and improving its quality.

[0059] Since the signal receiving port can receive all signals, it can improve the accuracy and sensitivity of the test to meet the needs of high-precision and high-sensitivity detection.

[0060] In use, pressurization unit 5 is activated, which applies stable confining pressure and axial pressure to pressure chamber 2 through confining pressure pump and axial pressure pump. The pressure sensor monitors the pressure of the preset rock sample in pressure chamber 2 in real time. When the confining pressure and axial pressure reach the preset value and stabilize at the preset value, pressurization of the rock sample is stopped. At this time, the detection unit 1 collects the ultrasonic longitudinal and transverse wave signals transmitted through the preset rock sample.

[0061] In this embodiment, a heating unit 6 for heating the interior of the pressure chamber 2 is provided on one side of the pressure chamber 2.

[0062] Specifically, the presence of heating unit 6 can simulate a real geological storage environment, improve the reliability and practicality of the test, and the heating of rock samples can take into account the acoustic properties of rocks under high temperature and high pressure in a CO2 environment.

[0063] Meanwhile, the heating unit 6 can reduce the impact of environmental factors on test results during the experiment. For example, by maintaining a constant temperature and pressure, data errors caused by environmental factors can be avoided.

[0064] Furthermore, the heating unit can accelerate the experimental process and enable faster data collection, thereby improving experimental efficiency;

[0065] Furthermore, the heating temperature of heating unit 6 can enable the testing of acoustic properties of different rocks at different temperatures, thereby expanding the testing range.

[0066] When in use, start the heating unit 6, set the preset heating temperature, place the pressure chamber 2 in a sealed environment, and monitor the temperature outside the pressure chamber 2 in real time through two temperature sensors installed outside the pressure chamber 2. After the temperature outside the pressure chamber 2 reaches the preset temperature and stabilizes at the preset temperature for at least 20 minutes, stop heating.

[0067] In this embodiment of the invention, the pressure chamber 2 is connected to a CO2 injection fluid unit 7 via pipelines. The CO2 injection fluid unit 7 is equipped with a corrosion-resistant constant speed and pressure pump and a pore fluid cooling system. The pore fluid cooling system includes a low-temperature constant temperature bath, a cooling coil, and a liquid storage container. One end of the pore fluid cooling system is connected to a CO2 gas cylinder, and the other end is connected to the corrosion-resistant constant speed and pressure pump. The other end of the corrosion-resistant constant speed and pressure pump is connected to a preset rock sample to be tested, which is used to build a rock acoustic testing environment that simulates the CO2 geological storage environment.

[0068] In this scheme, the pressure chamber 2 is connected to the CO2 injection fluid unit 7 via pipeline. Using CO2 as the test fluid, it can simulate the acoustic testing environment of rocks in the CO2 geological storage environment. This breaks the limitation that acoustic testing can only be performed on preset rock samples under normal temperature conditions, and provides strong data support for the acoustic testing of rock samples.

[0069] Furthermore, the CO2 injection unit is equipped with a corrosion-resistant constant speed and pressure pump, which can provide stable fluid pressure within a certain flow rate and velocity range. The corrosion-resistant material ensures that the fluid used will not have a corrosive effect on the pump.

[0070] Furthermore, one end of the pore fluid cooling system is connected to a CO2 gas cylinder, and the other end is connected to a corrosion-resistant constant-speed, constant-pressure pump to control the temperature of the fluid used. This method ensures that the fluid temperature remains within a certain range, avoiding any impact on the experimental results.

[0071] Furthermore, the other end of the corrosion-resistant constant speed and pressure pump is connected to a preset rock sample to be tested. Pressure can be applied to the preset rock sample through fluid to control the pore pressure of the rock sample. At the same time, the fluid can pass through the rock sample to obtain the acoustic signal of the saturated fluid rock.

[0072] During the experiment, a stable fluid pressure was used to control the pore pressure of the rock sample under test, and the fluid used was controlled at a certain temperature to ensure the experimental data.

[0073] In this embodiment of the invention, a preset confining pressure step size is adopted, and the confining pressure is gradually increased. By gradually increasing the confining pressure, the rock sample to be tested can be subjected to stress conditions similar to those underground, which can more realistically simulate the stress environment of underground reservoirs, thereby more accurately evaluating the rock mechanical properties of the reservoir; thus realizing rock variable confining pressure testing under preset pore pressure conditions.

[0074] Furthermore, maintaining the confining pressure of the rock sample in the pressurized chamber 2 to be greater than the pore pressure during the experiment can prevent the pore fluid from generating additional pressure on the rock sample, thereby ensuring the accuracy and precision of the experimental results. In the experiment, maintaining the confining pressure of the rock sample in the pressurized chamber to be greater than the pore pressure can ensure the safety of the experiment and avoid dangerous situations caused by excessive or unstable pressure.

[0075] In use, by starting the CO2 injection fluid unit 7, the corrosion-resistant constant speed and constant pressure pump is set to constant pressure mode, and the preset pore pressure is set. When the preset pore pressure of the rock sample to be tested injected with CO2 in the pressurization chamber 2 reaches a stable preset value, the pore pressure is stopped.

[0076] Repeatedly start the pressurization unit 5, set the preset confining pressure and axial pressure through the control unit 4, and monitor the pressure of the preset rock sample in the pressure chamber 2 in real time. When the confining pressure and axial pressure reach the preset values ​​and stabilize at the preset values, stop the pressurization step of the rock sample to be tested.

[0077] By using a preset confining pressure step size, the confining pressure is gradually increased to achieve rock variable confining pressure test under preset pore pressure conditions; and during the experiment, the confining pressure of the rock sample to be tested in the pressurized chamber 2 is always greater than the pore pressure.

[0078] Example 2:

[0079] Based on Example 1, such as Figure 1 As shown:

[0080] The pressure chamber 2 is equipped with a sealing sleeve 3, which encloses the pre-set rock sample to be tested in order to prevent the pre-set rock sample from being corroded.

[0081] In this embodiment of the invention, a sealing sleeve 3 is provided in the inner cavity of the pressure chamber 2, and the preset rock sample to be tested is wrapped in the sealing sleeve 3, which can effectively prevent the preset rock sample to be tested from being corroded and affecting the test results.

[0082] In this embodiment of the invention, the sealing sleeve 3 is made of CO2 corrosion resistant material to prevent the preset rock sample to be tested from being corroded.

[0083] In this embodiment of the invention, the CO2 corrosion-resistant material includes silicone rubber material and Teflon material used for corrosion protection.

[0084] In practice, stainless steels such as 304, 316, and 321 can resist corrosion from carbon dioxide.

[0085] High-chromium alloy steels, such as P22, P91, and P92, can resist corrosion from carbon dioxide media and have high strength and durability.

[0086] Products such as INCONEL 625 and HASTELLOY C-276 have good corrosion resistance and can be used in harsh environments such as high temperature, high pressure, and strong acids and alkalis.

[0087] Sodium-calcium glass, borosilicate glass and other glass materials have certain corrosion resistance, but their durability is poor and they are suitable for short-cycle experiments.

[0088] Polymer materials such as polyimide, polypropylene, and polyvinyl chloride have excellent corrosion resistance and toughness, making them suitable for small-scale devices and underground tests that do not require high strength.

[0089] In this embodiment of the invention, CO2 medium has strong corrosiveness, while silicone rubber and Teflon materials have good corrosion resistance, which can effectively protect the testing device and improve its service life.

[0090] Silicone rubber and Teflon materials have excellent high temperature resistance, can withstand high temperature and high pressure environments, and can ensure the stability and reliability of acoustic testing devices under high temperature and high pressure conditions.

[0091] Silicone rubber and Teflon materials have excellent sealing performance, which can ensure the stability and consistency of the internal medium of the testing device, and guarantee the accuracy and reliability of the test.

[0092] Silicone rubber and Teflon materials have good wear resistance, which can reduce the wear of the testing equipment caused by the external environment and improve the service life of the testing equipment.

[0093] Example 3:

[0094] Based on Example 2, such as Figure 1 As shown:

[0095] In this embodiment, one end of the ultrasonic probe is used to excite an ultrasonic signal to a preset rock sample to be tested, and the other end is used to receive the ultrasonic signal transmitted through the preset rock sample to be tested.

[0096] In this embodiment, the ultrasonic probe may be made of piezoelectric material, thermal expansion material, or magnetic material.

[0097] In this embodiment, the heating unit 6 uses an electric heating wire heating method.

[0098] In this embodiment, the heating wire is made of metal heating wire material, silicide heating wire material, or conductive ceramic heating wire material.

[0099] Heating unit 6 uses electric heating wire, which has a fast heating speed and can quickly heat the rock sample to the required temperature, thereby shortening the test time.

[0100] The heating wire heating method can precisely control the heating power and automatically adjust the heating amount as needed, thereby ensuring precise temperature control during the test.

[0101] The heating method using electric heating wires can distribute heat evenly to all parts, and uneven heating will not affect the accuracy of test results.

[0102] Ultrasonic probes can be made of piezoelectric, thermally expanding, or magnetic materials. Piezoelectric materials possess excellent mechanical properties and stability, enabling them to stably output sound wave signals. Therefore, they are commonly used in the sensor field and widely applied in acoustics. Furthermore, piezoelectric materials have a very small coefficient of thermal expansion, making them less susceptible to temperature changes and ensuring the accuracy of test results.

[0103] Thermally expandable materials expand when heated, and this expansion can generate ultrasonic signals. Therefore, thermally expandable materials can be used as materials for ultrasonic probes in fields such as thermal expansion acoustic measurement and temperature testing. At the same time, thermally expandable materials also have advantages such as high-temperature stability and corrosion resistance, ensuring their long-term stability in simulated carbon dioxide geological storage environments.

[0104] Magnetic materials deform under the influence of a magnetic field, and this deformation can generate ultrasonic signals. Therefore, magnetic materials can be used to make magnetoacoustic probes, which are applied in fields such as magnetoacoustic measurement and magnetostriction. Compared with other probe materials, magnetic materials have high sensitivity and can be used to detect minute changes. At the same time, these materials also have good properties in terms of heat resistance, corrosion resistance, and mechanical strength.

[0105] Example 4:

[0106] Based on Example 3, such as Figure 3 As shown:

[0107] Figure 3 The red line represents the curves showing the variation of P-wave and S-wave velocities in fully saturated supercritical CO2 rocks with confining pressure, obtained using the rock acoustic testing method for simulating a CO2 geological storage environment provided in this invention, at a temperature of 45°C and a pore pressure of 10 MPa. For ease of comparison, Figure 3The paper also shows the curves of the P and S wave velocities of dry rock (blue line) and saturated rock (green line) as a function of confining pressure at a temperature of 45℃. It can be seen that there are significant differences between the P and S wave velocities of saturated supercritical CO2 rocks and those of dry and saturated rocks. This provides a basis and support for using seismic monitoring of CO2 geological sequestration in the CCUS project.

[0108] Example 5:

[0109] An acoustic testing method for rocks in a simulated CO2 geological storage environment, and the specific steps of the testing method are as follows:

[0110] Place the preset rock sample to be tested in the pressure chamber 2, and attach the two ultrasonic probes of the detection unit 1 to the upper and lower end faces of the preset rock sample to be tested respectively.

[0111] Start heating unit 6, set the preset heating temperature, place pressure chamber 2 in a sealed environment, monitor the temperature outside pressure chamber 2 in real time through two temperature sensors installed outside pressure chamber 2, and stop heating after the temperature outside pressure chamber 2 reaches the preset temperature and stabilizes at the preset temperature for at least 20 minutes.

[0112] Start the pressurization unit 5, set the preset confining pressure and axial pressure through the control unit 4, and monitor the pressure of the preset rock sample in the pressure chamber 2 in real time. When the confining pressure and axial pressure reach the preset values ​​and stabilize at the preset values, stop pressurizing the rock sample.

[0113] Start the CO2 injection fluid unit 7, set the corrosion-resistant constant speed and constant pressure pump to constant pressure mode, and set the preset pore pressure. After the preset pore pressure of the rock sample to be tested in the pressurization chamber 2 reaches a stable preset value after CO2 injection, stop adding pore pressure and repeat step 3. Use the preset confining pressure step size to gradually increase the confining pressure to realize the rock variable confining pressure test under the preset pore pressure condition; and during the experiment, keep the confining pressure of the rock sample to be tested in the pressurization chamber 2 greater than the pore pressure.

[0114] Activate detection unit 1, and for each pore pressure point and confining pressure point in step 4, send a command through control unit 4 to excite ultrasonic waves to one end of the rock sample to be tested, and receive the ultrasonic longitudinal and transverse wave waveform signals collected after passing through the preset rock sample to be tested.

[0115] When the initial arrival time of the transmitted longitudinal and transverse wave waveforms of the rock sample to be tested is reached, and the preset length L of the sample to be tested and the zero-time t of the longitudinal wave at zero time of the ultrasonic probe are obtained, p0 and transverse wave at zero time t s0 Based on this, the rock P-wave velocity V in the simulated CO2 geological storage environment is calculated according to the following formula. p and transverse wave velocity V s :

[0116]

[0117] Where L is the sample length, t1 is the arrival time of the longitudinal wave, and t p0 When the longitudinal wave reaches zero, t2 is when the transverse wave arrives, and t... s0 When the transverse wave is at zero, and when the longitudinal wave is at zero, t p0 and transverse wave at zero time t s0 Acoustic testing can be performed by probe docking experiments or by replacing the rock sample to be tested with aluminum standard samples of different sizes.

[0118] It should be noted that, in this disclosure, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element limited by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0119] While the embodiments disclosed herein are as described above, the foregoing content is merely for the purpose of facilitating understanding of this disclosure and is not intended to limit this disclosure. Any person skilled in the art to which this disclosure pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope of this disclosure; however, the scope of patent protection of this disclosure shall still be defined by the appended claims.

Claims

1. An acoustic testing device for rocks simulating a CO2 geological storage environment, comprising a pressure chamber, characterized in that, A detection unit and a pressurization unit are coupled to the outer surface of the pressure chamber, and the detection unit and the pressurization unit are respectively electrically connected to a preset control unit; The detection unit detects the preset rock sample to be tested and feeds back the detection results to the control unit. The control unit controls the pressurization unit to apply a preset pressure value to the pressure chamber based on the detection results. When the pressure value reaches the preset value, the control unit sends an excitation and reception command for the rock sample to be tested to the detection unit and collects the arrival time of the transmitted ultrasonic waveform signal of the rock sample to be tested.

2. The acoustic testing device for simulating CO2 geological storage environment rocks as described in claim 1, characterized in that, The outer surface of the pressure chamber is also equipped with a heating unit for controlling and maintaining a constant temperature inside the pressure chamber.

3. The acoustic testing device for simulating CO2 geological storage environment rocks as described in claim 1, characterized in that, The pressure chamber is equipped with a sealing sleeve for enclosing the rock sample to be tested, and a CO2 fluid injection unit is provided outside the pressure chamber to maintain the pore pressure of the rock sample to be tested inside the sealing sleeve.

4. The acoustic testing device for simulating CO2 geological storage environment rocks as described in claim 3, characterized in that, The sealing sleeve is made of a material resistant to CO2 corrosion.

5. The acoustic testing device for simulating CO2 geological storage environment rocks as described in claim 4, characterized in that, The CO2-resistant materials used are silicone rubber and Teflon.

6. The acoustic testing device for simulating a CO2 geological storage environment as described in claim 3, characterized in that, The CO2 injection unit includes a corrosion-resistant constant-speed and constant-pressure pump and a pore fluid cooling system. One end of the corrosion-resistant constant-speed and constant-pressure pump is connected to the pore fluid cooling system, and the other end passes through a pipeline through a pressure chamber and a sealing sleeve into the rock sample to be tested. The other end of the pore fluid cooling system is connected to a CO2 cylinder. The phase of CO2 entering the corrosion-resistant constant-speed and constant-pressure pump is controlled by the pore fluid cooling system, and a preset pore pressure is applied to the rock sample to be tested by the corrosion-resistant constant-speed and constant-pressure pump.

7. The acoustic testing device for simulating CO2 geological storage environment rocks as described in claim 1, characterized in that, The pressure chamber is cylindrical to ensure a uniform pressure distribution inside.

8. The acoustic testing device for simulating a CO2 geological storage environment as described in claim 1, characterized in that, The detection unit includes two sets of ultrasonic probes for transmitting and receiving ultrasonic waves, and the two sets of ultrasonic probes are respectively in close contact with both ends of the rock sample to be tested.

9. The acoustic testing device for simulated CO2 geological storage environment as described in claim 1, characterized in that, The control unit includes a computer, which includes a signal control port and a signal receiving port. The signal control port is connected to a pressurization unit, and the signal receiving port is connected to a detection unit. The signal control port controls the pressurization unit to apply a preset pressure value to the pressure chamber, and the signal receiving port collects the arrival time of the ultrasonic waveform signal transmitted by the detection unit to the rock sample under test.

10. A method for acoustic testing of rocks in a simulated CO2 geological storage environment, the method using the acoustic testing apparatus for rocks in a simulated CO2 geological storage environment as described in any one of claims 1-9, characterized in that, The method includes: The preset rock sample to be tested is detected by the detection unit; The control unit controls the pressurization unit to apply a preset pressure value to the pressure chamber based on the detection results of the detection unit. When the pressure value reaches the preset value and stabilizes at the preset value, the pressurization of the rock sample to be tested is stopped. After the pressurization is stopped, the control unit sends a command to the detection unit to excite ultrasonic waves at one end of the preset test rock sample and to receive the ultrasonic longitudinal and transverse wave waveform signals collected after passing through the preset test rock sample. After the command is sent, the control unit picks up the initial arrival time of the longitudinal and transverse wave waveforms transmitted through the rock sample to be tested. This time can also be called the arrival time. Based on the preset length L of the sample to be tested and the preset ultrasonic probe zero time, which includes the longitudinal wave zero time t, the control unit then selects the initial arrival time. p0 and transverse wave at zero time t s0 Calculate the longitudinal wave velocity V of rocks in a simulated CO2 geological sequestration environment. p and transverse wave velocity V s : Where L is the sample length, t1 is the arrival time of the longitudinal wave, and t p0 When the longitudinal wave reaches zero, t2 is when the transverse wave arrives, and t... s0 It is when the transverse wave is at zero.

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