Fracturing and storage device and method based on supercritical CO2 injection into basalt

Abstract

The present invention discloses a fracturing and sealing device and method based on supercritical CO2 injection into basalt. The fracturing and sealing device includes: a test body module, including a basalt sample; an injection module, which injects the required gas, liquid or gas-liquid mixture into the test body module; a pressure loading module, which is connected to the test body and applies axial pressure and / or confining pressure to the test body module; wherein the injection module and the pressure loading module are configured to achieve fracturing of the basalt sample, as well as the radial permeability of the basalt sample after fracturing and the sealing of CO2 by the basalt sample after fracturing. It can overcome the limitations of the single function of traditional indoor test devices and achieve a comprehensive understanding of the fracturing and sealing process under complex formation environmental conditions; it is also convenient for analyzing the formation law of basalt fracture networks, evaluating the permeability of fracture networks, and comparing the feasibility and effectiveness of basalt mineralization and CO2 storage under different injection modes.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 storage, and in particular to a fracturing storage device and method based on supercritical CO2 injection into basalt. Background Art

[0002] Basalt, a widely distributed volcanic rock rich in alkaline elements, is considered an ideal carbon sequestration medium due to its potential for rapid mineralization and CO2 storage. It is well known that some basalt formations are located in active rift zones and are porous and highly permeable, making them suitable for direct injection of CO2 and water (or a mixture of H2S) for mineralization and carbon sequestration. However, the timing of eruption and the geological environment affect the density and porosity of basalt. In other words, some basalt formations are denser and stronger. Therefore, to effectively utilize these dense basalt formations for CO2 storage, fracturing is necessary to stimulate them, forming a large-scale, complex fracture network that provides abundant mineralization reaction space. Supercritical CO2 is a water-free fracturing fluid with unique thermophysical properties that offer advantages such as reduced fracture pressure, increased formation permeability, and reduced formation damage. Supercritical CO2 fracturing has emerged as a promising alternative to hydraulic fracturing in the efficient extraction of oil and gas fields. Therefore, the combined application of CO2 fracturing stimulation and mineralization storage in tight basalt formations can help achieve the "dual carbon" goals and is a sustainable solution.

[0003] In these scenarios, compared to on-site project costs, physical simulation testing is an economical and effective means of analyzing the performance of CO2 storage through fracturing. Statistics show that current indoor test equipment for CO2 fracturing storage has two main limitations: The equipment's single function lacks a combined fracturing and storage process; and this limitation further limits sample selection. For example, samples containing particulate matter such as fly ash cannot meet the requirements of fracturing and cannot simulate actual formation application requirements. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] In view of this, the present invention provides a fracturing and sealing device and method based on supercritical CO2 injection into basalt, wherein the fracturing and sealing device can overcome the limitations of the single function of traditional indoor test equipment, and can achieve a comprehensive understanding of complex formation environmental conditions and the sealing process; it is also convenient for analyzing the formation rules of basalt fracture networks, evaluating the permeability of the fracture networks, and comparing the feasibility and effectiveness of basalt mineralization and CO2 storage under different injection modes.

[0006] Specifically, the following technical solutions are included:

[0007] An embodiment of the first aspect of the present invention provides a fracturing and sealing device based on supercritical CO2 injection into basalt, the fracturing and sealing device comprising:

[0008] A test body module includes a basalt assembly, wherein the basalt assembly includes a basalt sample;

[0009] An injection module is used to inject the required gas, liquid or gas-liquid mixture into the test main module;

[0010] a pressure loading module, connected to the test body, for applying axial pressure and / or confining pressure to the test body module;

[0011] The injection module and the pressure loading module are configured to achieve fracturing of the basalt sample, as well as radial permeability of the basalt sample after fracturing and storage of CO2 by the basalt sample after fracturing.

[0012] Optionally, the injection module includes a supercritical CO2 preparation unit, a water injection unit and a mixed solution injection unit; the supercritical CO2 preparation unit is configured to achieve fracturing of the basalt sample and the radial permeability of the basalt sample after fracturing; the supercritical CO2 preparation unit, the water injection unit and the mixed solution injection unit are configured to achieve the sealing of CO2 by the basalt sample after fracturing; wherein, the supercritical CO2 preparation unit, the water injection unit and the mixed solution injection unit are connected in parallel to the test main module.

[0013] Optionally, the supercritical CO2 preparation unit includes:

[0014] CO2 cylinders;

[0015] A CO2 injection pump, one end of which is connected to the outlet of the CO2 cylinder, a pressure reducing valve is provided between the CO2 cylinder and the CO2 injection pump, and the other end of the CO2 injection pump is respectively connected to the test main module and the mixed solution injection unit;

[0016] The booster is arranged between the pressure reducing valve and the CO2 injection pump, and the booster is connected to the air compressor through a driving gas inlet.

[0017] Optionally, the water injection unit includes:

[0018] A water injection pump, one end of which is connected to the water tank, and the other end of which is communicated with the test main module and the mixed solution injection unit respectively.

[0019] Optionally, the mixed solution injection unit includes:

[0020] A mixed solution displacement container, wherein the first end of the mixed solution displacement container is connected to the supercritical CO2 preparation unit and the water injection unit respectively, the second end of the mixed solution displacement container is connected to the test main module, and the third end of the mixed solution displacement container is connected to the mixed solution displacement pump.

[0021] Optionally, the test subject module further includes:

[0022] Three-axle load-bearing frame;

[0023] A three-axis loading frame base, located within the three-axis loading frame;

[0024] A basalt assembly is disposed in a triaxial cavity, a heating and heat-insulating component is provided outside the triaxial cavity, the triaxial cavity is located on the base of the triaxial loading frame, and the heating and heat-insulating component is located in the triaxial loading frame;

[0025] An axial top cylinder, comprising a piston and an oil chamber, is provided below the base of the triaxial loading frame;

[0026] The ball-correcting force-transmitting top is arranged above the three-axis cavity, and the ball-correcting force-transmitting top abuts against the upper side of the basalt assembly through a force-transmitting column.

[0027] Optionally, the basalt assembly further comprises: a central through hole provided on the basalt sample, an upper packing assembly and a lower packing assembly located in the central through hole, and a fracturing hole section enclosed by the central through hole, the upper packing assembly and the lower packing assembly, wherein a high-pressure resistant pipe is provided in the lower packing assembly, and the high-pressure resistant pipe is used to connect the injection module and the pressure hole section;

[0028] A thin film heat shrink tube is jacketed on the outside of the basalt sample, an acoustic emission probe positioning sleeve is jacketed on the thin film heat shrink tube, and an acoustic emission probe is arranged between the thin film heat shrink tube and the acoustic emission probe positioning sleeve;

[0029] A radial deformation meter includes a test probe, the test probe abutting against the outer wall of the basalt sample through the thin film heat shrink tube, the test probe passing through the acoustic emission probe positioning sleeve, and a plurality of radial deformation meters evenly arranged in the circumferential direction at the same height of the basalt sample, the radial deformation meters and the acoustic emission probe being staggered;

[0030] The triaxial cavity and the basalt assembly form a confined pressure medium cavity.

[0031] Optionally, the basalt assembly further comprises: a central through hole provided on the basalt sample; and

[0032] An upper pressure pad is arranged above the basalt sample, and a central through hole is provided on the upper pressure pad;

[0033] a lower pressure pad, arranged below the basalt sample;

[0034] The triaxial cavity and the basalt assembly enclose a radial seepage cavity.

[0035] Optionally, the basalt assembly further comprises: a central through hole provided on the basalt sample; and

[0036] A CO2-resistant sealing rubber cylinder is sheathed outside the basalt sample, and the CO2-resistant sealing rubber cylinder and the triaxial cavity form a confined pressure medium cavity.

[0037] Optionally, the basalt assembly further comprises:

[0038] An upper plug is provided above the triaxial cavity, and an outlet is provided on the upper plug, the outlet is communicated with the confining pressure medium cavity, and the confining pressure medium cavity is communicated with the oil collecting tank through a pipeline;

[0039] An upper pressure head is provided between the upper plug and the basalt sample, wherein a seepage groove is provided in the upper pressure head and an injection pipe is provided on the upper pressure head, and the injection pipe is communicated with the seepage groove;

[0040] A lower plug is provided below the triaxial cavity, and is provided with a data line terminal, a confining pressure medium channel, a seepage medium channel, and a mixed solution channel. The data line terminal is connected to the data integration box, and the confining pressure medium channel, the seepage medium channel, and the mixed solution channel are connected to the injection module.

[0041] The lower pressure head is arranged between the basalt sample and the lower plug.

[0042] Optionally, the pressure loading module includes:

[0043] An axial pressure servo pump is connected to the oil chamber of the axial top cylinder, and the axial pressure servo pump provides axial pressure for the basalt assembly;

[0044] A confining pressure servo pump is connected to the basalt assembly, and the confining pressure servo pump provides confining pressure for the basalt assembly.

[0045] Optionally, the fracturing and sealing device further includes a metering component, which is in communication with the test main module and includes:

[0046] A gas-liquid separator, a back pressure valve is provided between the gas-liquid separator and the test main module, the gas outlet of the gas-liquid separator is connected to a gas flow meter, the liquid outlet of the gas-liquid separator is connected to a liquid collecting bottle, and an electronic balance is provided under the liquid collecting bottle;

[0047] The fracturing and sealing device further includes a fluid channel, and the fluid channel is used to connect the injection module and the test main module.

[0048] An embodiment of the second aspect of the present invention provides a fracturing and sealing method based on supercritical CO2 injection into basalt, using the above-mentioned fracturing and sealing device, the fracturing and sealing method includes the following steps:

[0049] Install the test main module;

[0050] Starting the pressure loading module to apply pressure to the test main module and monitoring changes in the pressure;

[0051] According to the requirements of fracturing, seepage and sealing, the injection module is started to realize the fracturing, seepage and sealing tests on the main test module;

[0052] After the sealing test is completed, the basalt sample in the main test module is taken out to observe the surface morphology of the fracture and the distribution of mineral components on the test surface.

[0053] The embodiment of the present invention provides a fracturing and sealing device and a fracturing method based on supercritical CO2 injection into basalt, wherein the fracturing and sealing device includes a test body module, the test body module includes a basalt sample, the required gas, liquid or gas-liquid mixture is injected into the test body module through the injection module, and the axial pressure and confining pressure of the test subject module are applied through the pressure loading module so that the test body module can meet the test requirements. After the basalt sample is fractured by the fracturing and sealing device of the present application, the permeability of the basalt sample after fracturing is obtained, and the CO2 is sealed. It can be seen that the present application overcomes the limitation of the single function of traditional indoor test equipment and can obtain a comprehensive understanding of complex formation environmental conditions and sealing processes; at the same time, through the three test angles of fracturing, seepage and sealing of basalt samples, it can not only analyze the formation law of basalt fracture network, but also evaluate the permeability of the fracture network, and compare the feasibility and effectiveness of basalt mineralization and CO2 sealing under different injection modes. At the same time, the fracturing and storage device of this application will help researchers in the fields of geological engineering, environmental science, and energy to better understand the behavior of CO2 in basalt formation environments, and then optimize CO2 injection strategies, to achieve effective management and utilization of CO2 from the dual perspectives of fracturing and storage, and provide technical support for achieving the "dual carbon" goals.

[0054] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0056] Figure 1 is a schematic diagram of a fracturing and sealing device according to one embodiment of the present invention;

[0057] Figure 2 is a schematic diagram of a lower plug according to an embodiment of the present invention;

[0058] Figure 3 A schematic diagram of a basalt assembly for fracturing according to one embodiment of the present invention;

[0059] Figure 4 A schematic diagram of a basalt assembly for radial seepage according to one embodiment of the present invention;

[0060] Figure 5 A schematic diagram of a basalt assembly for storage according to one embodiment of the present invention;

[0061] Figure 6 1 is a schematic flow chart of the steps of a fracturing and sealing method according to one embodiment of the present invention.

[0062] in, Figures 1 to 5 The corresponding relationship between the reference numerals and component names is as follows:

[0063] 01CO2 gas cylinder, 02 pressure reducing valve, 0301-0315 first stop valve - fifteenth stop valve, 04 air compressor, 05 booster, 06 water injection pump, 07 water tank, 08CO2 injection pump, 09 mixed solution displacement container, 10 mixed solution displacement pump, 11 pressure loading module, 12 axial pressure servo pump, 13 confining pressure servo pump, 14 axial top cylinder, 1501-1506 first pressure sensor - sixth pressure sensor, 16 three-axis loading frame base, 17 ball correction force top, 18 three-axis load frame, 19 lower plug, 1901 data line terminal, 1902 confining pressure medium channel, 1903 seepage medium channel, 1904 mixed solution channel, 20 upper plug, 21 upper pressure head, 22 injection pipeline, 23 seal Trough, 24 triaxial cavity, 25 basalt assembly, 2501 upper packing assembly, 2502 lower packing assembly, 2503 basalt sample, 2504 fracturing hole section, 2505 film heat shrink tube, 2506 confining pressure medium cavity, 2507 central through hole, 2508 acoustic emission probe, 2509 acoustic emission probe positioning sleeve, 2510 radial seepage cavity, 2511 upper pressure pad, 2512 lower pressure pad, 2513 CO2 resistant sealing rubber cylinder, 2514 strain gauge, 2515 radial deformation meter, 26 lower pressure head, 27 oil collecting tank, 28 gas flow meter, 29 data integration box, 30 heating and insulation components, 31 back pressure valve, 32 gas-liquid separator, 33 liquid collecting bottle, 34 electronic balance, 35 fluid channel, 36 force transmission column. DETAILED DESCRIPTION

[0064] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0065] Before further describing the embodiments of the present invention in detail, the directional terms involved in the embodiments of the present invention, such as "upper part", "lower part" and "side part", do not have the meaning of limiting the scope of protection of the present invention.

[0066] To make the technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0067] Figure 1 Schematic diagram of a fracturing and sealing device according to one embodiment of the present invention.

[0068] like Figure 1 As shown, one embodiment of the present invention provides a fracturing and sealing device based on supercritical CO2 injection into basalt, the fracturing and sealing device comprising:

[0069] The test main body module includes a basalt assembly 25, and the basalt assembly 25 includes a basalt sample 2503;

[0070] Injection module, injecting the required gas, liquid or gas-liquid mixture into the test main module;

[0071] The pressure loading module 11 is connected to the test body and applies axial pressure and / or confining pressure to the test body module;

[0072] The injection module and the pressure loading module 11 are configured to achieve the fracturing of the basalt sample 2503 , as well as the radial permeability of the basalt sample 2503 after fracturing and the storage of CO 2 by the basalt sample 2503 after fracturing.

[0073] It should be noted that the fracturing and sealing device includes a test main module, which includes a basalt sample 2503. The required gas, liquid, or gas-liquid mixture is injected into the test main module through the injection module, and the axial pressure and confining pressure of the test subject module are applied to the test subject module through the pressure loading module 11, so that the test main module can meet the test requirements. After the basalt sample 2503 is fractured by the fracturing and sealing device of this application, the permeability of the fractured basalt sample 2503 is obtained, and the CO2 is sealed. It can be seen that this application overcomes the limitations of the single function of traditional indoor test devices and can obtain a comprehensive understanding of complex formation environmental conditions and the sealing process. At the same time, through the three test angles of fracturing, seepage, and sealing of the basalt sample 2503, it can not only analyze the formation law of the basalt fracture network, but also evaluate the permeability of the fracture network, and compare the feasibility and effectiveness of basalt mineralization and CO2 storage under different injection modes. At the same time, the fracturing and storage device of this application will help researchers in the fields of geological engineering, environmental science, and energy to better understand the behavior of CO2 in basalt formation environments, and then optimize CO2 injection strategies, to achieve effective management and utilization of CO2 from the dual perspectives of fracturing and storage, and provide technical support for achieving the "dual carbon" goals.

[0074] In a feasible embodiment, the injection module includes a supercritical CO2 preparation unit, a water injection unit and a mixed solution injection unit; the supercritical CO2 preparation unit is configured to achieve fracturing of the basalt sample 2503 and the radial permeability of the basalt sample 2503 after fracturing; the supercritical CO2 preparation unit, the water injection unit and the mixed solution injection unit are configured to achieve the sealing of CO2 by the basalt sample 2503 after fracturing; wherein, the supercritical CO2 preparation unit, the water injection unit and the mixed solution injection unit are connected in parallel to the test main module.

[0075] The injection module includes a supercritical CO2 production unit, a water injection unit, and a mixed solution injection unit. These units are connected to the mixed solution injection unit via pipelines to inject CO2 and water into the unit. A circulating agitator is located upstream of the mixed solution injection unit, allowing for variable speed mixing of different solutions.

[0076] In one feasible embodiment, the supercritical CO2 production unit includes:

[0077] CO2 cylinder 01;

[0078] A CO2 injection pump 08, one end of which is connected to the outlet of the CO2 cylinder 01, a pressure reducing valve 02 is provided between the CO2 cylinder 01 and the CO2 injection pump 08, and the other end of the CO2 injection pump 08 is respectively connected to the test main module and the mixed solution injection unit;

[0079] The booster 05 is provided between the pressure reducing valve 02 and the CO2 injection pump 08, and the booster 05 is connected to the air compressor 04 through the driving gas inlet.

[0080] It should be noted that by adjusting the boost ratio of the supercharger 05 in the supercritical CO2 preparation unit and cooperating with the heating and insulation component 30 outside the triaxial cavity 24 in the test main module, supercritical CO2 of specified pressure and temperature can be prepared.

[0081] It is understood that in order to achieve parallel connection of the supercritical CO2 production unit, water injection unit, and mixed solution injection unit, shutoff valves are required on the connecting pipes. A first shutoff valve 0301 is installed between the CO2 injection pump 08 and the pressurizing valve. A second shutoff valve 0302 is installed on the pipe connecting the booster 05 and the outlet of the CO2 injection pump 08. A third shutoff valve 0303 and a fourth shutoff valve 0304 are installed on the pipes at both ends of the CO2 injection pump 08, respectively. A fourth pressure sensor 1504 is also installed between the CO2 injection pump 08 and the CO2 cylinder 01.

[0082] In a feasible embodiment, the water injection unit includes:

[0083] A water injection pump 06 , one end of which is connected to the water tank 07 , and the other end of which is respectively connected to the test main module and the mixed solution injection unit.

[0084] A fifth shutoff valve 0305 is provided between the water tank 07 and the water injection pump 06, a sixth shutoff valve 0306 is provided above the water injection pump 06, a seventh shutoff valve 0307 is provided between the water injection pump 06 and the mixed solution displacement container 09, and an eighth shutoff valve 0308 is provided between the water injection pump 06 and the CO2 injection pump 08. A fifth pressure sensor 1505 is also provided at the outlet of the water injection pump 06.

[0085] In a feasible embodiment, the mixed solution injection unit includes:

[0086] The mixed solution displacement container 09, the first end of the mixed solution displacement container 09 is connected to the supercritical CO2 preparation unit and the water injection unit respectively, the second end of the mixed solution displacement container 09 is connected to the test main module, and the third end of the mixed solution displacement container 09 is connected to the mixed solution displacement pump 10.

[0087] A ninth shutoff valve 0309 is provided between the inlet of the mixed solution displacement container 09 and the CO2 injection pump 08, a tenth shutoff valve 0310 is provided between the outlet of the mixed solution displacement container 09 and the main test module, and an eleventh shutoff valve 0311 is provided between the mixed solution displacement pump 10 and the mixed solution displacement container 09. Furthermore, a sixth pressure sensor 1506 is provided between the mixed solution displacement pump 10 and the mixed solution displacement container 09.

[0088] It should be noted that the CO2 injection pump 08, the water injection pump 06 and the mixed solution displacement pump 10 are all equipped with the functions of constant injection displacement and constant injection volume, and are divided into two operating modes: manual control and automatic control. They can record and save data such as fluid pressure, displacement, and injection liquid volume in real time. Different injection schemes are designed by adjusting the displacement and pressure, such as constant, step-by-step, and circulating types. A temperature sensor is installed inside the pump cavity of the CO2 injection pump 08, and the output port of the CO2 injection pump 08 is equipped with a fourth pressure sensor 1504 for monitoring the temperature and pressure changes of the CO2 at the front end of different injection schemes; the output port of the water injection pump 06 is equipped with a fifth pressure sensor 1505, and the output port of the mixed solution displacement pump 10 is equipped with a sixth pressure sensor 1506 for monitoring the pressure changes of the injected fluid.

[0089] Optionally, the upstream top of the mixed solution displacement container 09 is equipped with a circulating agitator, which can adjust the speed to mix different solutions, and the downstream displacement medium is the water in the mixed solution displacement pump 10. The middle of the mixed solution displacement container 09 is equipped with a high-seal, low-inertia suspended piston to allow the downstream displacement medium to drive the upstream mixed solution and then inject it into the basalt sample 2503.

[0090] In a feasible implementation, the test subject module includes:

[0091] Three-axis load-bearing frame 18;

[0092] A three-axis loading frame base 16 is located within the three-axis loading frame 18;

[0093] The basalt assembly 25 is disposed in the triaxial cavity 24. A heating and heat-insulating component 30 is provided outside the triaxial cavity 24. The triaxial cavity 24 is located on the triaxial loading frame base 16. The heating and heat-insulating component 30 is located in the triaxial loading frame 18.

[0094] An axial top cylinder 14 includes a piston and an oil chamber. The axial top cylinder 14 is disposed below the triaxial loading frame base 16;

[0095] The ball-correcting force-transmitting top 17 is disposed above the triaxial cavity 24 , and the ball-correcting force-transmitting top 17 abuts against the upper side of the basalt assembly 25 through the force-transmitting column 36 .

[0096] Among them, it is necessary to carry out fracturing test, seepage test and sealing test on the main test module. When carrying out the fracturing test, the hydraulic oil is driven by the axial pressure servo pump 12 in the pressure loading module 11, input into the oil tank of the axial top cylinder 14, push the piston upward, apply force to the triaxial loading frame base 16, and set the upward speed or displacement as needed to complete the axial pressure loading. At the same time, the hydraulic oil is driven by the confining pressure servo pump 13 in the pressure loading module 11, and oil is injected into the confining pressure medium cavity 2506 until the hydraulic oil flows out from the outlet of the upper plug 20 to the oil collecting tank 27, so as to realize the loading of the confining pressure. The confining pressure medium cavity 2506 is enclosed by the basalt assembly 25 and the triaxial cavity 24. A temperature sensor is installed in the confining pressure medium cavity 2506 to monitor the formation temperature of the simulated basalt, and the temperature change control is realized by heating the insulation component 30. The upper plug 20 and the lower plug 19 are connected to the triaxial cavity 24 through multiple sealing grooves 23. The sealing grooves are set on the outer periphery of the upper plug 20 and the lower plug 19. O-rings are set in the sealing grooves. When the upper plug 20 and the lower plug 19 are inserted into the triaxial cavity 24, the O-rings will be compressed between the contact surfaces of the plugs and the triaxial cavity 24, realizing the system sealing function, ensuring that the medium in the confining pressure medium cavity 2506 does not leak and the pressure is maintained. The ball-correcting force transmission top 17 above the triaxial load frame 18 ensures that the end face of the upper pressure head 21 maintains close contact with the end face of the basalt sample 2503. After waiting for the temperature in the fracturing hole section 2504 to reach the experimental design value and stabilize, the CO2 injection pump 08 in the supercritical CO2 preparation module is turned on to perform supercritical CO2 fracturing of the basalt sample 2503. It should be noted that the depth and size of the sealing groove 23 only need to match the size of the O-ring to ensure that the O-ring is neither over-compressed during installation, causing damage or aging of the O-ring, nor too loose to form an effective seal.

[0097] After the fracturing test, the axial and confining pressures are alternately unloaded to conduct a seepage test. The acoustic emission probe positioning sleeve 2509 on the outer side of the cylindrical specimen is removed, and the surface film heat shrink tubing 2505 is removed. The upper and lower packer assemblies 2501 and 2502 are then removed. An upper pressure pad 2511 with a central through-hole 2507 and a lower pressure pad 2512 without a central through-hole 2507 are then installed to form the basalt assembly 25 for the radial seepage test. At this point, the axial pressure servo pump 12 is activated to apply axial pressure to the basalt assembly 25, ensuring that the seepage medium flows only from the central through-hole 2507 toward the injection pipe 22 of the upper pressure head 21. The supercritical CO2 preparation unit is connected to the confining pressure medium channel 1902 on the lower plug 19. The CO2 injection pump 08 is activated, set to constant pressure injection mode, and the radial seepage cavity 2510 is filled with the seepage medium CO2. The radial permeability is then calculated based on the data monitored by the gas flow meter 28 in the metering assembly.

[0098] After the radial seepage test is completed, the axial pressure is unloaded and the sealing test is carried out. Remove the upper pressure pad 2511 and the lower pressure pad 2512, install the CO2-resistant sealing rubber tube 2513, and form the basalt assembly 25 for the seam network mineralization sealing test. Disconnect the supercritical CO2 preparation unit from the confining pressure medium channel 1902 of the lower plug 19, connect the supercritical CO2 preparation unit to the mixed solution injection unit, and connect the whole to the mixed solution channel 1904 on the lower plug 19, and then connect it to the injection pipe 22 of the upper pressure head 21, and move the metering component to the fluid channel 35 interface to realize the injection and extraction of the sealing solution. Axial and confining pressures were alternately applied to the basalt assembly 25. The water injection pump 06 and CO2 injection pump 08 were activated, pumping CO2 and water into the mixed solution displacement container 09. The mixed solution displacement pump 10 was then started, set to injection mode, and the sealing solution was injected into the fractured basalt assembly 25, beginning the sealing test. During the test, the mineralized solution was measured, weighed, and subjected to ion analysis. Specifically, after depressurizing the assembly 25, the sealing medium was extracted from the confining pressure medium chamber 2506. After extraction, the original sealing test conditions were restored and the sealing process continued. After the sealing test, the axial and confining pressures were alternately unloaded, and the basalt sample 2503 was removed. The fracture surface morphology and the distribution of surface mineral composition were observed.

[0099] Figure 3 FIG. 1 is a schematic diagram of a basalt assembly for fracturing according to one embodiment of the present invention.

[0100] In one possible implementation, Figure 3As shown, the basalt assembly 25 further includes: a central through hole 2507 provided on the basalt sample 2503, an upper packing assembly 2501 and a lower packing assembly 2502 located within the central through hole 2507, and a fracturing hole section 2504 enclosed by the central through hole 2507, the upper packing assembly 2501, and the lower packing assembly 2502. A high-pressure resistant pipe is provided within the lower packing assembly 2502, and the high-pressure resistant pipe is used to connect the injection module and the pressure hole section 2504.

[0101] A thin film heat shrink tube 2505 is placed outside the basalt sample 2503. An acoustic emission probe positioning sleeve 2509 is placed outside the thin film heat shrink tube 2505. An acoustic emission probe 2508 is placed between the thin film heat shrink tube 2505 and the acoustic emission probe positioning sleeve 2509.

[0102] The radial deformation gauge 2515 includes a test probe, which is in contact with the outer wall of the basalt sample 2503 through a thin film heat shrink tube 2505. The test probe passes through the acoustic emission probe positioning sleeve 2509. Multiple radial deformation gauges 2515 are evenly arranged in the circumferential direction at the same height of the basalt sample 2503. The radial deformation gauges 2515 are staggered with the acoustic emission probe 2508.

[0103] strain gauge 2514, provided on basalt sample 2503;

[0104] The triaxial cavity 24 , the upper pressure head 21 , the lower pressure head 26 , the upper plug 20 , the lower plug 19 , and the basalt assembly 25 enclose a confined pressure medium cavity 2506 .

[0105] Specifically, during the fracturing test, the basalt assembly 25 is required to ensure that the basalt sample 2503 is isolated from the confining pressure medium (hydraulic oil). This is achieved through the cooperation of sealing grooves 23 and thin film heat shrink tubing 2505 on the upper and lower pressure heads 21 and 26. Sealing grooves 23 are provided on the outer peripheries of the upper and lower pressure heads 21 and 26, and O-rings are installed in the sealing grooves 23. When the upper and lower pressure heads 21 and 26 are inserted into the triaxial cavity 24, the system seal of the fracturing test is achieved. Seepage grooves are provided on the end faces of the upper and lower pressure heads 21 and 26, and are located in the upper and lower pressure heads 21 and 26. The seepage grooves on the upper pressure head 21 are connected to the injection pipeline, and the seepage grooves on the lower pressure head 26 are connected to the fluid channel. At the same time, in order to ensure the reception of the acoustic wave signal of the acoustic emission probe 2508, a layer of coupling agent is applied on the outer side of the basalt sample 2503, and the thin film heat shrink tube 2505 is tightened to the basalt sample 2503, and the acoustic emission probe positioning sleeve 2509 is slid from top to bottom. The outer wall of the acoustic emission probe positioning sleeve 2509 is provided with multiple probe holes and through grooves. The probe holes are used to place the acoustic emission probe 2508, and the through groove is used to place the test probe of the radial deformation meter 2515. A layer of coupling agent is applied again in the probe holes, and then the acoustic emission probe 2508 is inserted and fixed with a spring clip. Finally, the acoustic emission probe positioning sleeve 2509 is penetrated, and the radial deformation meter 2515 is installed in the through groove so that the test probe of the radial deformation meter 2515 is in contact with the basalt sample. In this embodiment, four radial deformation marks 2515 are provided, and the angle between two adjacent radial deformation meters 2515 is 90°. In this embodiment, the thickness of the thin film heat shrink tube 2505 is 0.1 mm to 0.2 mm. The thin film heat shrink tube 2505 is provided to prevent the confining pressure medium in the confining pressure medium cavity 2606 from directly contacting the basalt sample 2503, that is, the hydraulic oil cannot directly contact the basalt sample 2503. It is understood that the thickness of the heat shrink tubing 2505 affects the transmission of acoustic signals. The density and elastic modulus of the heat shrink tubing 2505 affect the propagation speed and attenuation of acoustic waves within it. Thicker heat shrink tubing 2505 typically has a higher mass, which can lead to increased acoustic signal attenuation. When acoustic waves propagate from the sample to the interface of the heat shrink tubing, they may be partially reflected and refracted, especially when the acoustic impedances of the interfacial materials differ significantly. Increasing the thickness of the heat shrink tubing 2505 increases the interfacial area, potentially introducing more signal loss. A thicker heat shrink tubing 2505 causes the acoustic waves to travel a longer path during transmission, thereby increasing acoustic attenuation. As acoustic signals propagate through a material, their signal strength gradually weakens with increasing propagation distance. In other words, a thicker heat shrink tubing 2505 results in poorer transmission. Therefore, thinner heat shrink tubing 2505 should be selected to minimize acoustic attenuation and signal distortion.Typically, the thickness of the thin film heat shrink tubing 2505 should be controlled between 0.1mm and 0.2mm to minimize the impact on the acoustic emission signal, and a suitable coupling agent should be used to improve the transmission efficiency of the sound waves. The coupling agent is a medium used to ensure the transmission of sound waves between the acoustic emission probe 2508 and the material being tested (such as the basalt sample 2503). Its main function is to eliminate the air gap between the acoustic emission probe 2508 and the surface of the basalt sample 2503, ensuring that the sound waves can be effectively transmitted, thereby ensuring the accurate reception of the acoustic emission signal. The coupling agent is preferably high-vacuum silicone grease, which has excellent chemical stability, high temperature resistance, and high adhesion, especially for use when good contact needs to be maintained for a long time during acoustic emission or ultrasonic testing. The spring clip is hinged to the outer wall of the acoustic emission probe positioning sleeve 2509 and is located near the probe hole slot. The spring clip is rotated to press the acoustic emission probe 2508 against the basalt sample 2503.

[0106] It should be noted that acoustic emission probes 2508 are used to monitor crack formation and propagation; analyze the failure mechanism of basalt sample 2503 and infer its fracture characteristics; locate crack locations, identify their origins and network distribution; and assess the fracturing and permeability of the basalt rock to which basalt sample 2503 belongs. Radial deformation meter 2515 also includes a support base to which the test probes are bolted. The test probes are evenly distributed on the outer surface of basalt sample 2503 to measure strain at multiple radial locations. Multiple test probes form a complete radial measurement network, ensuring accurate assessment of the overall deformation of the sample.

[0107] Basalt sample 2503 is typically cylindrical and has a central through-hole 2507. The diameter of central through-hole 2507 is 1 / 5 of the diameter of basalt sample 2503, with an allowable error of ±0.1 mm. The inner wall of central through-hole 2507 must be smooth. Fracturing hole section 2504 is formed by upper and lower packer assemblies 2501 and 2502. The height of fracturing hole section 2504 is 1 / 10 of the height of basalt sample 2503, with an allowable error of ±0.2 mm. This error range is based on the International Society for Rock Mechanics and relevant ISO standards, helping to ensure test accuracy and consistency and making data comparable across different tests.

[0108] It should be noted that during the fracturing test, it is necessary to collect the axial deformation, radial deformation, and acoustic emission signals of the basalt sample 2503, as well as the axial strain and radial strain outside the basalt sample 2503 around the fracturing hole section 2504, the temperature and pressure of the fluid inside the fracturing hole section 2504, and the temperature within the triaxial cavity 24. The above-collected parameter data is transmitted to the data integration box 29 via the data line terminal 1901. During the fracturing test, collecting data such as temperature, pressure, deformation, strain, and acoustic emission signals is crucial for studying the mechanical behavior of the material (basalt sample 2503) and the process of crack formation. This data not only helps to understand the physical mechanism of the test, but also provides important information for optimizing fracturing schemes and practical applications. In other words, these data work together to help fully understand the formation and expansion of cracks and the response behavior of basalt during basalt fracturing; they provide important experimental basis for evaluating the formation mechanism of the fracture network, optimizing fracturing technology, and predicting the failure mode of the material.

[0109] It is understandable that a fourteenth shut-off valve 0314 is provided between the upper plug 20 and the oil collecting tank 27 , and a second pressure sensor 1502 is provided between the upper plug 20 and the oil collecting tank 27 . The second pressure sensor 1502 is used to monitor the confining pressure data of the fracturing sealing device.

[0110] Figure 4 FIG. 1 is a schematic diagram of a basalt assembly for radial seepage according to one embodiment of the present invention.

[0111] In one possible implementation, Figure 4 As shown, the basalt assembly 25 further includes: a central through hole 2507 provided on the basalt sample 2503; and

[0112] An upper pressure pad 2511 is disposed above the basalt sample 2503 and has a central through hole 2507;

[0113] A lower pressure pad 2512 is provided below the basalt sample 2503;

[0114] The triaxial cavity 24 and the basalt assembly 25 enclose a radial seepage cavity 2510 .

[0115] Specifically, during the seepage test, a radial seepage chamber 2510 was formed by the upper pressure head 21, lower pressure head 26, upper plug 20, and lower plug 19 of the triaxial chamber 24 and basalt assembly 25. An upper pressure pad 2511 containing a central through-hole 2507 was positioned between the upper pressure head 21 and the basalt sample 2503, while a lower pressure pad 2512 without a central through-hole 2507 was positioned between the lower pressure head 26 and the basalt sample 2503. The axial end was sealed by applying load via the axial pressure servo pump 12, ensuring that the flow path of the seepage medium was from the radial seepage chamber 2510 through the pressure fracture to the central through-hole 2507 of the sample.

[0116] Among them, the seepage test selects a supercritical CO2 preparation unit as the input of the seepage medium, and a seepage groove is provided in the upper pressure head 21, which is connected to the injection pipe 22. The injection pipe 22 is perpendicular to the central axis of the upper pressure head 21. At the same time, the connection combination of the seepage medium channel 1903 inside the lower plug 19 serves as the output of the seepage medium, and is connected to the metering component to monitor flow changes and calculate radial permeability. It should be noted that radial permeability refers to the ability of a fluid medium to penetrate radially (usually from the center to the outside) in a material. It is an important physical parameter for characterizing porous media materials such as rocks. In basalt fracturing tests and other fields such as underground fluid storage, oil and gas extraction, and geothermal development, monitoring flow changes and calculating radial permeability can be used to evaluate the permeability of materials and understand the flow characteristics of fluid media in materials; optimize the fracture network and fracturing process, improve the connectivity and permeability of fractures; and improve fluid storage efficiency to ensure that the fluid effectively penetrates and is sealed in the rock.

[0117] Figure 5 FIG. 2 is a schematic diagram of a basalt assembly 25 for storage according to an embodiment of the present invention.

[0118] In one possible implementation, Figure 5 As shown, the basalt assembly 25 further includes: a central through hole 2507 provided on the basalt sample 2503; and

[0119] The CO2-resistant sealing rubber tube 2513 is sheathed on the outside of the basalt sample 2503 . The CO2-resistant sealing rubber tube 2513 and the triaxial cavity 24 enclose a confined pressure medium cavity 2506 .

[0120] During the containment test, the entire CO2-resistant sealing rubber cylinder 2513 enclosed the basalt sample 2503, the upper pressure head 21, and the lower pressure head 26, ensuring that the confining pressure medium would not come into direct contact with the basalt sample 2503. The CO2-resistant sealing rubber cylinder 2513 here functions similarly to the thin film heat shrink tubing 2505 used in the fracturing test. Specifically, the triaxial cavity 24, the upper pressure head 21, the lower pressure head 26, the upper plug 20, the lower plug 19, and the CO2-resistant sealing rubber cylinder 2513 enclosed a confining pressure medium cavity 2506.

[0121] The radial seepage chamber 2510 and the confining pressure medium chamber 2506 are similar in space, but the purpose of each chamber is different under different test conditions. It can be understood that in the fracturing test, the confining pressure medium chamber 2506 is enclosed by the triaxial chamber 24, the upper pressure head 21, the lower pressure head 26, the upper plug 20, the lower plug 19, and the thin film heat shrink tube 2505; in the seepage test, the radial seepage chamber 2510 is enclosed by the triaxial chamber 24, the upper pressure head 21, the lower pressure head 26, the upper plug 20, the lower plug 19, and the basalt sample 2503; in the sealing test, the confining pressure medium chamber 2506 is enclosed by the triaxial chamber 24, the upper pressure head 21, the lower pressure head 26, the upper plug 20, the lower plug 19, and the CO2-resistant sealing rubber tube 2513.

[0122] Specifically, during the sealing test, the mixed solution injection unit is used as the input end, and the output end is connected to the metering component. The mixed solution is injected through the mixed solution channel 1904 on the lower plug 19, through the seepage groove in the lower pressure head 26, to the basalt sample 2503, and then through the seepage groove in the upper pressure head 21 to the injection pipe 22. The injection pipe 22 is connected to the seepage medium channel 1903 of the lower plug 19 through pipelines and joints to the metering component. According to the sealing time and injection plan, the time for sampling the mineralized solution is selected, the solution is quantitatively taken, the ion concentration in the solution is detected and analyzed, the basalt sample 2503 is removed, the sample morphology and mineral distribution are observed and analyzed, and the effectiveness of the basalt mineralization sealing is evaluated. Among them, after the basalt sample 2503 is removed, in order to observe and analyze the morphology and mineral distribution of the basalt sample 2503 and evaluate the effectiveness of the basalt mineralization sealing, it is necessary to use a variety of experimental means and analytical methods to conduct a detailed study of the basalt sample 2503. These are all based on some external detection instruments not mentioned in this patent. For example: Observation of sample morphology: Observation of the morphological changes of the sealed basalt sample 2503 through SEM, optical microscopy, CT and other methods, and analysis of the morphology after mineral reaction; Mineral distribution analysis: Use XRD, EPMA, EDS and other methods to analyze the mineral phase distribution and chemical composition, and evaluate the progress of mineralization reaction; Sealing effectiveness assessment: Evaluation of the degree of mineralization reaction and sealing efficiency through the determination of mineralization product amount, porosity change, CO2 absorption and mineral stability.

[0123] It is understandable that the timing of sampling is based on the sealing time and the injection scheme, and usually includes sampling at the initial, mid-term, and final stages, with the purpose of monitoring the dynamic changes of the mineralization reaction. Quantitative liquid sampling can accurately control the volume of each sample through equipment such as a measuring cylinder, a sampling tube, and a syringe. For example, the liquid volume can be set to 5 ml, 10 ml, or other specific volumes per sampling, and the liquid volume can be adjusted according to experimental needs. Although the mineralization solution is injected through the mixed solution injection unit, the components in the solution will change over time during the reaction process after injection. Therefore, sampling is not carried out during the injection process, but at different time points after the injection to monitor the progress of the reaction. Through multiple sampling, the changes in the chemical composition of the mixed solution can be captured and the dynamic process of the mineralization reaction can be analyzed.

[0124] Figure 2 Schematic diagram of a lower plug according to an embodiment of the present invention.

[0125] In one possible implementation, Figure 2 As shown, the basalt assembly 25 further includes:

[0126] The upper plug 20 is disposed above the triaxial cavity 24 and is provided with an outlet, which is communicated with the confining pressure medium cavity 2506 , and the confining pressure medium cavity 2506 is communicated with the oil collecting tank 27 through a pipeline;

[0127] The upper pressure head 21 is provided between the upper plug 20 and the basalt sample 2503. The upper pressure head 21 is provided with a seepage groove. The upper pressure head 21 is provided with a liquid injection pipe 22, and the liquid injection pipe 22 is connected to the seepage groove.

[0128] The lower plug 19 is provided below the triaxial cavity 24 and is provided with a data line terminal 1901, a confining pressure medium channel 1902, a seepage medium channel 1903, and a mixed solution channel 1904. The data line terminal 1901 is connected to the data integration box 29, and the confining pressure medium channel 1902, the seepage medium channel 1903, and the mixed solution channel 1904 are connected to the injection module.

[0129] The lower pressure head 26 is arranged between the basalt sample 2503 and the lower plug 19.

[0130] Among them, the upper pressure head 21 is provided with an injection pipe 22, and the injection pipe 22 is arranged perpendicular to the axis of the upper pressure head. The injection pipe 22 is used to connect the seepage groove in the upper pressure head 21, so that the seepage medium can be input into the seepage groove through the injection pipe 22. The injection pipe 22 can be selectively connected to multiple places, such as a mixed solution injection unit, a metering component, etc., only through corresponding pipelines. The injection pipe 22 has a threaded interface, which can be connected to different components such as valves, joints, etc., and a sealed and stable connection is achieved through threads. It is understandable that when the injection pipe 22 is not in use, a threaded plug (usually a threaded plug for closing a port) can be used for temporary closure.

[0131] In a feasible embodiment, the pressure loading module 11 includes:

[0132] The axial pressure servo pump 12 is connected to the oil chamber of the axial top cylinder 14, and the axial pressure servo pump 12 provides axial pressure for the basalt assembly 25;

[0133] The confining pressure servo pump 13 is in communication with the basalt assembly 25 , and provides confining pressure for the basalt assembly 25 .

[0134] Among them, a twelfth stop valve 0312 is set between the axial pressure servo pump 12 and the axial top cylinder 14 to control the opening and closing of the axial pressure servo pump 12, and a thirteenth stop valve 0313 is set between the confining pressure servo pump 13 and the basalt assembly 25 to control the opening and closing of the confining pressure servo pump 13.

[0135] It should be noted that the pressure loading module 11 includes an axial pressure servo pump 12 and a confining pressure servo pump 13, and the axial pressure servo pump 12 and the confining pressure servo pump 13 apply axial pressure and confining pressure to the basalt sample respectively. It is understandable that the media of axial pressure and confining pressure are both hydraulic oil. A first pressure sensor 1501 is set at the outlet of the axial pressure servo pump 12, and a second pressure sensor 1502 is set between the upper plug 20 and the oil collecting tank 27. The second pressure sensor 1502 is used to monitor the confining pressure data of the fracturing sealing device, and can monitor the maintenance status of the axial pressure and confining pressure during the entire fracturing sealing test. It is understandable that the second pressure sensor 1502 can also be set at the outlet of the confining pressure servo pump 13, and the pressure value of the confining pressure can be obtained.

[0136] In a feasible embodiment, the fracturing and sealing device further includes a metering component, which is in communication with the test main module and includes:

[0137] A gas-liquid separator 32 is provided. A back pressure valve 31 is provided between the gas-liquid separator 32 and the test main module. The gas outlet of the gas-liquid separator 32 is connected to the gas flow meter 28. The liquid outlet of the gas-liquid separator 32 is connected to the liquid collecting bottle 33. An electronic balance 34 is provided under the liquid collecting bottle 33.

[0138] The fracturing and sealing device further includes a fluid channel 35 , which is used to connect the injection module and the test main module.

[0139] Among them, a fifteenth stop valve 0315 is connected in parallel with the back pressure valve 31, and a third pressure sensor 1503 is connected in series with the back pressure valve 31, and the third pressure sensor 1503 is used to obtain the fluid pressure of the seepage medium during seepage. The fluid channel 35 is a universal flexible port, which can be connected to different units in the injection module according to the test plan. The interface of the fluid channel 35 is a multi-purpose interface, and the connection method is a compression fitting. In other words, the fluid channel 35 can be connected to different components or piping systems. The design of this interface allows a flexible connection method so that different devices in the system (such as metering components, injection modules, fluid output devices, etc.) can be easily connected to the fluid channel.

[0140] It should be noted that the backpressure valve 31 is located closer to the basalt assembly 25 than the gas-liquid separator 32. A fifteenth shut-off valve 0315 is connected in parallel with the backpressure valve 31, and a third pressure sensor 1503 is also connected in series. This arrangement allows for better control and monitoring of the pressure within the fracturing and containment device, and allows for flexible operation via a bypass branch when needed. The backpressure valve 31 is used to maintain the system's upstream pressure, ensuring that the pressure in the injection pipeline 22 does not drop below a set value. The fifteenth shut-off valve 0315, connected in parallel with the backpressure valve 31, serves as a bypass control component. In certain situations, the backpressure valve 31 can be closed and the fifteenth shut-off valve 0315 opened, allowing fluid to bypass the backpressure valve 31 and flow directly to the downstream portion of the system. For example, when the fracturing and containment device is processing a gas-liquid mixture, the backpressure valve 31 can be closed and the fifteenth shut-off valve 0315 opened to enable the bypass path, allowing the gas-liquid mixture to be introduced directly into the gas-liquid separator 32 for separation. The gas-liquid separator 32 separates the gas and liquid, ensuring they do not interfere with each other during subsequent measurements. The backpressure valve 31 maintains system pressure balance; however, it is generally not suitable for handling a two-phase gas-liquid mixture. The gas flowmeter 28 measures gas flow and, in turn, permeability. The liquid collection flask 33 collects the liquid, and the electronic balance 34 measures its weight for sample analysis after the mineralization reaction.

[0141] Figure 6 1 is a schematic flow chart of the steps of a fracturing and sealing method according to one embodiment of the present invention.

[0142] like Figure 6 As shown, another embodiment of the present invention provides a fracturing and sealing method based on supercritical CO2 injection into basalt, using the above-mentioned pressure sealing device, the fracturing and sealing method includes the following steps:

[0143] Step 1: Install the test main module;

[0144] Step 2: Start the pressure loading module, apply pressure to the test main module, and monitor the pressure change;

[0145] Step 3: According to the requirements of fracturing, seepage and sealing, the injection module is started to realize the fracturing, seepage and sealing tests on the main test module;

[0146] Step 4: After the sealing test is completed, the basalt sample in the main test module is taken out to observe the surface morphology of the fracture and the distribution of mineral components on the test surface.

[0147] Specifically, a basalt sample 2503 containing a central through-hole 2507 was prepared and placed in the triaxial chamber 24 to form the basalt assembly 25. In this embodiment, a cylindrical basalt sample 2503 with a diameter of 50 mm and a height of 10 mm was selected. The central through-hole 2507 was drilled into the basalt sample 2503, the hole walls of the central through-hole 2507 were cleaned, and the location of the acoustic probe was marked on the outside of the basalt sample 2503. Strain gauges 2514 were attached to the outside of the basalt sample 2503 near the fracturing hole section 2504 at 90° intervals. Connect the lower packer assembly 2502 to the lower pressure head 26 and place it in the central through-hole 2507 of the basalt sample 2503. Then, insert the upper packer assembly 2501 into the central through-hole 2507 from the top of the basalt sample 2503. Place the upper pressure head 21 at the upper end of the basalt sample 2503, aligning the central axis of the upper pressure head 21 with the central axis of the basalt sample 2503 to ensure a more uniform axial pressure. Apply acoustic couplant to the location of the acoustic emission probe 2508 on the basalt sample 2503, then slide in the thin film heat shrink tubing 2505 to tighten the basalt sample 2503. Then, slide in the acoustic emission probe positioning sleeve 2509, and attach the acoustic emission probe 2508 to the space between the acoustic emission probe positioning sleeve 2509 and the thin film heat shrink tubing 2505 using couplant. Secure the acoustic emission probe 2508 with a spring clip. Install the radial deformation gauge 2515. After the above installation is completed, the basalt assembly 25 required for the fracturing test is formed in the triaxial cavity 24.

[0148] The pressure loading module 11 is activated, that is, the axial pressure servo pump 12 and the confining pressure servo pump 13 are alternately activated, axial pressure and confining pressure are alternately applied to the basalt sample 2503, and pressure changes are monitored (axial pressure is monitored via the first pressure sensor 1501, and confining pressure is monitored via the second pressure sensor 1502). The heating and heat preservation component 30 outside the triaxial chamber 24 is activated to heat the triaxial chamber 24 and the basalt sample 2503. The air compressor 04 and supercharger 05 in the supercritical CO2 production unit are activated to prepare CO2 at the set pressure and store it in the CO2 injection pump 08. Specifically, the basalt assembly 25 for the fracturing test is checked for proper installation. Once installed, it is assembled with the triaxial chamber 24 to complete the system sealing, and the heating and heat preservation component 30 is installed on the entire exterior of the triaxial chamber 24. The pressure loading module 11 is activated, and the operating modes of the axial pressure servo pump 12 and the confining pressure servo pump 13 are set. The basalt sample 2503 is subjected to alternating axial and confining pressure loading. The pressure loading module 11 simultaneously records and stores data such as the loading mode, axial pressure, confining pressure, and displacement. The heating and insulation component 30 is activated to heat the entire triaxial cavity 24 and the basalt sample 2503 within it. The temperature can be set from room temperature to 300°C to simulate the temperature conditions of the basalt formation. The CO2 cylinder 01, pressure reducing valve 02, second shut-off valve 0302, air compressor 04, and supercharger 05 are activated. The first shut-off valve 0301, third shut-off valve 0303, and fourth shut-off valve 0304 are closed, and the boost ratio of supercharger 05 is set to produce the specified high-pressure CO2 and store it in the CO2 injection pump 08. The axial pressure is calculated by combining the load applied by the axial pressure servo pump 12 (obtained by the first pressure sensor 1501) and the load-bearing area of ​​the basalt sample 2503 (displayed directly on the data terminal of the pressure loading module 11). The confining pressure servo pump 13 injects hydraulic oil into the confining pressure medium chamber 2506. The liquid pressure is the confining pressure, which is directly measured by the second pressure sensor 1502. The strain gauge 2514 obtains the data of the axial and radial strains of the basalt sample 2503 at the location of the strain gauge 2514. The radial deformation meter 2515 measures the radial change of the basalt sample 2503.

[0149] It should be noted that by opening the CO2 cylinder 01, the pressure reducing valve 02, and the first shut-off valve 0301, and closing the air compressor 04, the boost valve, the second shut-off valve 0302, the third shut-off valve 0303, and the fourth shut-off valve 0304, CO2 at a pressure slightly lower than that of the CO2 cylinder 01 can be input into the CO2 injection pump 08. It is understood that the pump chamber of the CO2 injection pump 08 is equipped with a constant temperature circulator, which can control the temperature of the fluid inside the CO2 injection pump 08 to range from -20°C to 100°C. The supercritical CO2 preparation unit is not limited to the triaxial cavity 24 cooperating to prepare supercritical CO2, but can also prepare and store gaseous or liquid CO2 at a specified temperature and pressure.

[0150] After the temperature in the fracturing hole section 2504 reaches the actual test value and stabilizes, the CO2 injection pump 08 in the supercritical CO2 preparation unit is turned on to perform supercritical CO2 fracturing on the basalt sample 2503. It should be noted that when conducting the fracturing test, the eighth stop valve 0308, the ninth stop valve 0309, and the tenth stop valve 0310 need to be closed to ensure that supercritical CO2 can be directly injected into the fracturing hole section 2504. It is understood that it is not limited to CO2 fracturing, and hydraulic fracturing or other solution fracturing can also be used. This can be achieved by adjusting the opening and closing states of the fourth stop valve 0304, the eighth stop valve 0308, the ninth stop valve 0309, and the tenth stop valve 0310, which will not be described in detail.

[0151] After the fracturing test is completed, the axial pressure and confining pressure of the fracturing and sealing device are alternately unloaded through the pressure loading module 11 .

[0152] Slide out the acoustic emission probe positioning sleeve 2509 and the film heat shrink tube 2505 on the outside of the basalt sample 2503, and remove the upper isolation assembly 2501 and the lower isolation assembly 2502. Then, install the upper pressure pad 2511 containing the central through hole 2507 and the lower pressure pad 2512 without the central through hole 2507 to form the basalt assembly 25 required for the radial seepage test. Specifically, after completing the unloading of the axial pressure and the confining pressure, ensure that the confining pressure medium (hydraulic oil) in the triaxial cavity 24 has been completely discharged, contact the assembly of the triaxial cavity 24, push aside the spring clip to remove the acoustic emission probe 2508, slide out the acoustic emission probe positioning sleeve 2509 on the outside of the basalt sample 2503, and remove the film heat shrink tube 2505 on the surface of the basalt sample 2503. After removing the upper pressure head 21 and taking out the basalt sample 2503, the upper and lower packer assemblies 2501 and 2502 within the extractor are removed, leaving the central through-hole 2507 hollow. A lower pressure pad 2512 is installed between the lower portion of the basalt sample 2503 and the lower pressure head 26, and an upper pressure pad 2511 is installed between the upper end face of the basalt sample 2503 and the upper pressure head 21, forming the basalt assembly 25 required for the seepage test.

[0153] Only the axial pressure servo pump 12 in the pressure loading module 11 is activated to ensure that the seepage medium flows out of the central through-hole 2507 toward the injection pipe 22 of the upper pressure head 21. It should be noted that to ensure the correct path of radial seepage, a certain axial pressure is applied to the basalt sample 2503 by the axial pressure servo pump 12 to compress the lower pressure pad 2512 and the upper pressure pad 2511. In this embodiment, the axial pressure used in the seepage test is 1 MPa.

[0154] Connect the supercritical CO2 preparation unit to the confining pressure medium channel 1902 on the lower plug 19, turn on the CO2 injection pump 08, set the constant pressure injection mode, ensure that the radial seepage cavity 2510 is filled with the seepage medium CO2, and the seepage medium passes through the radial seepage cavity 2510 and enters the central through hole 2507 through the pressure fracture, and flows out of the central through hole 2507 to the metering component, and then the gas flow meter 28 in the metering component monitors the data and calculates the radial permeability. Specifically, connect the supercritical CO2 preparation unit and the confining pressure medium channel 1902 on the lower plug 19, and connect the injection pipe 22 in the upper pressure head 21, the seepage medium channel 1903 and the metering component. Open the CO2 cylinder 01, pressure reducing valve 02, first stop valve 0301, and fourth stop valve 0304; shut off the air compressor 04, supercharger 05, second stop valve 0302, third stop valve 0303, eighth stop valve 0308, ninth stop valve 0309, and tenth stop valve 0310; adjust the pressure reducing valve 02 to fill the entire radial seepage cavity 2510 with the seepage medium CO2. Set the upstream pressure of the seepage (greater than atmospheric pressure), close the back pressure valve 31, and open the fifteenth stop valve 0315 (i.e., atmospheric pressure); or open the back pressure valve 31 (lower than the upstream pressure) and close the fifteenth stop valve 0315 to create a seepage pressure differential. This is used to read and record the monitoring data on the gas flow meter 28, thereby obtaining radial permeability. Once the seepage pressure differential is created, the seepage medium can flow, allowing the data of the seepage medium to be monitored. The gas flow meter 28 is used to monitor the volume flow rate, that is, the flow rate of the seepage medium when passing through the basalt sample 2503. The data for calculating the radial permeability also require: upstream pressure and downstream pressure (these are the initial parameters that need to be set for the seepage test), the geometric parameters of the basalt sample 2503 (inner and outer diameters, height), and dynamic viscosity (this is based on the test parameters and consulted in the chemical manual). Since the calculation of radial permeability is not the solution protected by this application, but common knowledge used in the field, it will not be elaborated here.

[0155] After the radial seepage test is completed, the CO2 injection pump 08 is turned off, the axial pressure is unloaded, the upper pressure pad 2511 and the lower pressure pad 2512 are removed, and the CO2 resistant sealing rubber cylinder 2513 is installed to form the Xuanwu element assembly required for the sealing test.

[0156] Disconnect the supercritical CO2 preparation unit and the confining pressure medium channel 1902, connect the supercritical CO2 preparation unit and the mixed solution injection unit, and plug the mixed solution channel 1904 of the lower plug 19 as a whole, then connect it to the injection pipe 22 of the upper pressure head 21, and move the metering component to the fluid channel 35 interface to realize the injection and extraction of the sealed solution.

[0157] The pressure loading module 11 is started to apply axial pressure and confining pressure alternately to the sealing basalt assembly 25 .

[0158] Start the water injection pump 06 and the CO2 injection pump 08 to deliver CO2 and water to the mixed solution container. Specifically, close the sixth shut-off valve 0306, open the fifth shut-off valve 0305 and the water injection pump 06, set the negative displacement mode, fill the pump chamber of the water injection pump 06 with water, close the fifth shut-off valve 0305 and the eighth shut-off valve 0308, open the seventh shut-off valve 0307, ​​start the water injection pump 06, and inject a certain amount of water into the mixed solution displacement container 09. The amount of injected liquid is recorded. It should be noted that the ninth shut-off valve 0309 and the tenth shut-off valve 0310 remain closed during the above water injection process. The water here refers to deionized water, but is not limited to deionized water. It can also be sodium bicarbonate solution, seawater, or brackish water. Close the water injection pump 06 and the seventh stop valve 0307, ​​open the fourth stop valve 0304 and the ninth stop valve 0309, turn on the CO2 injection pump 08 (as long as there is CO2 in the pump chamber of the injection pump 08, it can be directly injected into the mixed solution displacement container 09 through the injection pump 08), and continuously input high-pressure CO2 into the mixed solution displacement container 09. At the same time, turn on the circulation agitator in the mixed solution displacement container 09 to promote the dissolution of CO2. After reaching saturation, close the CO2 injection pump 08, the ninth stop valve 0309 and the fourth stop valve 0304.

[0159] Start the mixed solution displacement pump 10, set the injection mode, inject the sealing solution into the sealing basalt assembly 25, and start the sealing test. During the sealing test, measure the mineralized solution in a timely manner, weigh it, and perform ion analysis. Specifically, open the tenth stop valve 0310 and the eleventh stop valve 0311, start the mixed solution displacement pump 10, set the displacement mode, and inject the sealing solution into the basalt sample 2503 after fracturing. Among them, the mineralized solution is the solution left after the sealing test, which can be unreacted CO2 (if CO2 gas is used for sealing) or other gases. The dissolved ions generated by the mineralization reaction, such as carbonate ions (CO3 2- ) and metal ions (calcium, magnesium, iron, etc.) generated after reacting with CO2; the generated carbonate minerals may be partially precipitated in the solution, and some may be dissolved in deionized water. CO2 is dissolved in deionized water and reacts with minerals in basalt sample 2503, that is, the mineralization reaction occurs during the process of CO2 injection and reaction with minerals. As the test progresses, the mineralization reaction will gradually occur, and the mineralized products will gradually accumulate. It should be noted that at the beginning of the sealing test, the deionized water is pure, but during the mineralization reaction, the CO2 in the water will react with the rock minerals (basalt sample 2503) to produce different ions (such as carbonate ions and metal ions, such as calcium (Ca 2+ ), magnesium (Mg 2+ ), iron (Fe 2+) etc.). Therefore, the mineralized solution will contain dissolved ions generated by the mineralization reaction, reflecting the progress and effectiveness of the mineralization reaction. Therefore, during the experiment, researchers will measure, weigh, and sample the mineralized solution after the reaction at appropriate times. Ion analysis can be performed using techniques such as ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) to detect the concentrations of different ions in the solution. The progress of the mineralization reaction can be analyzed by measuring the concentrations of ions such as calcium, magnesium, and iron in the solution, combined with the carbonate ion concentration. The amount of mineral produced can be determined by calculating the molar concentration of the ions and the mass of the products.

[0160] It should be noted that the injection modes include the following three: slow continuous injection at a low constant displacement; injection at a constant volume and medium speed to a specified liquid volume; and injection of a certain amount of solution in batches, with the interval between batches being several days or months. It can be understood that the sealing experiment includes static system sealing and dynamic system sealing. The difference between the two lies in the status of the back pressure valve 31 and the fifteenth stop valve 0315 in the metering component. The static sealing system refers to closing the back pressure valve 31 and the fifteenth stop valve 0315. The pressure of the entire sealing system depends on the output pressure of the mixed solution displacement pump 10. The fifteenth stop valve 0315 is opened when liquid is taken regularly, and the system pressure is replenished after the liquid is taken. The dynamic sealing system refers to closing the fifteenth stop valve 0315 and setting the working pressure of the back pressure valve 31 to be constant lower than the output pressure of the mixed solution displacement pump 10. The pressure difference is usually set to 0.5MPa, thereby forming a micro-dynamic flow state. The output pressure of the mixed solution displacement pump 10 is typically lower than the confining pressure to ensure that the basalt sample 2503 is properly encapsulated. Otherwise, high fluid pressure could damage the outer film heat shrink tubing 2505, causing the sealed solution to leak into the confining pressure medium chamber 2506, resulting in test failure. Theoretically, the injected CO2 and water or mixed solution in the basalt sample 2503, as well as the reacted mineralized solution, remain confined to the basalt sample 2503 and will not leak outside the film heat shrink tubing 2505.

[0161] It can be understood that the static sealing system refers to keeping the sealing medium and basalt sample 2503 in a static state during the test, and not allowing the fluid to flow in the fracturing sealing device. The pressure and temperature in the fracturing sealing device can be maintained stable, but there is neither continuous fluid flow nor externally applied flow stimulation. After the sealing medium (such as CO2 or mineralizing solution) is injected into the sealing cavity, the basalt sample 2503 contacts the sealing medium, but the two are in a relatively static state and there is no continuous fluid circulation. Applicable scenarios and experimental plans: used to study the long-term stability of mineralization reactions, simulate underground sealing environments, and rocks or minerals with low permeability. Characteristics of the experimental results: slow reaction rate, suitable for long-term experiments.

[0162] A dynamic sealing system refers to a system in which there is continuous fluid flow during the test, usually by externally applying pressure or flow control, so that the sealing medium (such as mineralizing solution, CO2 gas, etc.) continuously circulates through the basalt sample 2503. The fracturing sealing device maintains stable pressure and fluid flow rate to simulate the fluid movement in a real underground environment. The fluid circulates continuously in the fracturing sealing device, and the flow of the fluid strengthens the transfer of reactants and enhances the rate of the sealing reaction. Applicable scenarios and experimental plans: used to study the mineralization rate under flow conditions, simulate actual underground fluid conditions, and highly permeable rocks (such as sandstone, basalt, etc.). Characteristics of the experimental results: fast reaction speed, suitable for short-term experiments. The fracturing sealing device of this application can meet the requirements of static tests and dynamic tests at the same time, and improve the scope of application of the fracturing sealing device.

[0163] After the sealing test, the axial pressure and confining pressure were alternately unloaded, and the basalt sample 2503 was taken out to observe the surface morphology of the fracture and the distribution of mineral components on the test surface.

[0164] In the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless otherwise clearly defined.

[0165] Other embodiments of the present invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as illustrative only.

[0166] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fracturing and storage device based on supercritical CO2 injection into basalt, characterized in that: The fracturing and sealing device comprises: A test body module includes a basalt assembly, wherein the basalt assembly includes a basalt sample; An injection module is used to inject the required gas, liquid or gas-liquid mixture into the test main module; a pressure loading module, connected to the test body, for applying axial pressure and / or confining pressure to the test body module; The injection module and the pressure loading module are configured to achieve fracturing of the basalt sample, as well as radial permeability of the basalt sample after fracturing and storage of CO2 by the basalt sample after fracturing; The test subject module also includes: Three-axle load-bearing frame; A three-axis loading frame base, located within the three-axis loading frame; A basalt assembly is disposed in a triaxial cavity, a heating and heat-insulating component is provided outside the triaxial cavity, the triaxial cavity is located on the base of the triaxial loading frame, and the heating and heat-insulating component is located in the triaxial loading frame; An axial top cylinder, comprising a piston and an oil chamber, is provided below the base of the triaxial loading frame; A ball-correcting force-transmitting top is provided above the triaxial cavity, and the ball-correcting force-transmitting top abuts against the upper side of the basalt assembly through a force-transmitting column; The basalt assembly further includes: a central through hole provided on the basalt sample, an upper packing assembly and a lower packing assembly located in the central through hole, and a fracturing hole section enclosed by the central through hole, the upper packing assembly and the lower packing assembly, wherein a high-pressure resistant pipe is provided in the lower packing assembly, and the high-pressure resistant pipe is used to connect the injection module and the pressure hole section; A thin film heat shrink tube is jacketed on the outside of the basalt sample, an acoustic emission probe positioning sleeve is jacketed on the thin film heat shrink tube, and an acoustic emission probe is arranged between the thin film heat shrink tube and the acoustic emission probe positioning sleeve; A radial deformation meter includes a test probe, the test probe abutting against the outer wall of the basalt sample through the thin film heat shrink tube, the test probe passing through the acoustic emission probe positioning sleeve, and a plurality of radial deformation meters evenly arranged in the circumferential direction at the same height of the basalt sample, the radial deformation meters and the acoustic emission probe being staggered; a strain gauge, disposed on the basalt sample; Wherein, the triaxial cavity and the basalt assembly enclose a confining pressure medium cavity; The basalt assembly further includes: a central through hole provided on the basalt sample; and An upper pressure pad is arranged above the basalt sample, and a central through hole is provided on the upper pressure pad; a lower pressure pad, arranged below the basalt sample; Wherein, the triaxial cavity and the basalt assembly enclose a radial seepage cavity; The basalt assembly further includes: a central through hole provided on the basalt sample; and A CO2-resistant sealing rubber cylinder is sheathed outside the basalt sample, and the CO2-resistant sealing rubber cylinder and the triaxial cavity form a confined pressure medium cavity.

2. The fracturing and sealing device based on supercritical CO2 injection into basalt according to claim 1 is characterized in that: The injection module includes a supercritical CO2 preparation unit, a water injection unit and a mixed solution injection unit; the supercritical CO2 preparation unit is configured to achieve fracturing of the basalt sample and the radial permeability of the basalt sample after fracturing; the supercritical CO2 preparation unit, the water injection unit and the mixed solution injection unit are configured to achieve the sealing of CO2 by the basalt sample after fracturing; wherein, the supercritical CO2 preparation unit, the water injection unit and the mixed solution injection unit are connected in parallel and communicated with the test main module.

3. The fracturing and sealing device based on supercritical CO2 injection into basalt according to claim 2, characterized in that: The supercritical CO2 preparation unit comprises: CO2 cylinders; A CO2 injection pump, one end of which is connected to the outlet of the CO2 cylinder, a pressure reducing valve is provided between the CO2 cylinder and the CO2 injection pump, and the other end of the CO2 injection pump is respectively connected to the test main module and the mixed solution injection unit; The booster is arranged between the pressure reducing valve and the CO2 injection pump, and the booster is connected to the air compressor through a driving gas inlet.

4. The fracturing and sealing device based on supercritical CO2 injection into basalt according to claim 2, characterized in that: The water injection unit comprises: A water injection pump, one end of which is connected to the water tank, and the other end of which is communicated with the test main module and the mixed solution injection unit respectively.

5. The fracturing and sealing device based on supercritical CO2 injection into basalt according to claim 2, characterized in that: The mixed solution injection unit includes: A mixed solution displacement container, wherein the first end of the mixed solution displacement container is connected to the supercritical CO2 preparation unit and the water injection unit respectively, the second end of the mixed solution displacement container is connected to the test main module, and the third end of the mixed solution displacement container is connected to the mixed solution displacement pump.

6. The fracturing and sealing device based on supercritical CO2 injection into basalt according to claim 1, characterized in that: The basalt assembly further comprises: An upper plug is provided above the triaxial cavity, and an outlet is provided on the upper plug, the outlet is communicated with the confining pressure medium cavity, and the confining pressure medium cavity is communicated with the oil collecting tank through a pipeline; An upper pressure head is provided between the upper plug and the basalt sample, wherein a seepage groove is provided in the upper pressure head and an injection pipe is provided on the upper pressure head, and the injection pipe is communicated with the seepage groove; A lower plug is provided below the triaxial cavity, and is provided with a data line terminal, a confining pressure medium channel, a seepage medium channel, and a mixed solution channel. The data line terminal is connected to the data integration box, and the confining pressure medium channel, the seepage medium channel, and the mixed solution channel are connected to the injection module. The lower pressure head is arranged between the basalt sample and the lower plug.

7. The fracturing and sealing device based on supercritical CO2 injection into basalt according to claim 1, characterized in that: The pressure loading module includes: An axial pressure servo pump is connected to the oil chamber of the axial top cylinder, and the axial pressure servo pump provides axial pressure for the basalt assembly; A confining pressure servo pump is connected to the basalt assembly, and the confining pressure servo pump provides confining pressure for the basalt assembly.

8. The fracturing and sealing device based on supercritical CO2 injection into basalt according to claim 1, characterized in that: The fracturing and sealing device further includes a metering assembly, which is in communication with the test main module and includes: A gas-liquid separator, a back pressure valve is provided between the gas-liquid separator and the test main module, the gas outlet of the gas-liquid separator is connected to a gas flow meter, the liquid outlet of the gas-liquid separator is connected to a liquid collecting bottle, and an electronic balance is provided under the liquid collecting bottle; The fracturing and sealing device further includes a fluid channel, and the fluid channel is used to connect the injection module and the test main module.

9. A fracturing and sealing method based on supercritical CO2 injection into basalt, using the fracturing and sealing device according to any one of claims 1 to 8, characterized in that: The fracturing sealing method comprises the following steps: Install the test main module; Starting the pressure loading module to apply pressure to the test main module and monitoring changes in the pressure; According to the requirements of fracturing, seepage and sealing, the injection module is started to realize the fracturing, seepage and sealing tests on the main test module; After the sealing test is completed, the basalt sample in the main test module is taken out to observe the surface morphology of the fracture and the distribution of mineral components on the test surface.

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