Rock fracture mineralization experimental device and experimental method

Abstract

The application discloses a rock fracture mineralization experiment device and an experiment method, and belongs to the technical field of mineralization experiments.The device comprises a three-dimensional transparent rock fracture model, a liquid injection unit, a hydraulic and waste liquid monitoring unit, a visual monitoring unit and a data acquisition and processing unit.The liquid injection unit adopts two sets of independent pulse injection devices to respectively transport fluid to the first inlet and the second inlet of the model in a pulse injection mode.In the visual monitoring unit, a fluorescence imaging and three-dimensional imaging system can perform double-color fluorescence tracing imaging, particle image velocimetry on the fluid in the model, and three-dimensional image acquisition on the fracture channel.The data acquisition and processing unit can acquire pulse control signals, pressure signals, flow signals, turbidity signals and image signals under a unified time reference.The application can study fluid mixing, mineral precipitation, local plugging and hydraulic response evolution in rough rock fractures under different pulse injection conditions.

Description

Technical Field

[0001] This application relates to the field of mineralization experimental technology, and more specifically, to a rock fracture mineralization experimental apparatus and method. Background Technology

[0002] In natural environments, the geometric distribution of rock fissures is complex and varied, exhibiting a heterogeneous and intersecting pattern, often accompanied by the mixing, reaction, and migration of different solutions. When two fluids containing reacting ions come into contact within a rough fissure, mineral dissolution, crystal growth, and precipitation blockage may occur. The presence of precipitates alters the local fissure opening, further affecting flow characteristics and causing dynamic changes in fissure pressure differential, outlet flow rate, and solute residence time. This is of great significance for many engineering projects, such as geothermal reinjection, carbon dioxide geological sequestration, underground energy development, seepage prevention and reinforcement of fissure rock masses, and mineralization sealing. Therefore, real-time monitoring of the mineralization process, degree of mixing, and distribution and migration trajectory of derived precipitates after solution mixing within rock fissures is necessary.

[0003] However, existing fracture reaction transport experiments often use constant pressure boundaries, and a small number of pulse injection studies mainly focus on improving injection capacity or inducing crack propagation, making it difficult to clarify the influence mechanism of pulse pressure on the degree of solution mixing, reaction hotspots, and the migration trajectory of the generated precipitates. Summary of the Invention

[0004] This application aims to provide a rock fracture mineralization experimental apparatus and method to study the effects of different pulse action modes on the mixing degree and velocity field of two fluids in a three-dimensional rough cross fracture, reveal the changes in the local fracture aperture caused by the formation, local dissolution or scouring and migration of mineral precipitation, and further evaluate the effects of local blockage on the hydraulic aperture, permeability and flow capacity of the fracture.

[0005] A rock fracture mineralization experimental apparatus, comprising: A three-dimensional transparent rock fracture model has a three-dimensional intersecting fracture channel with a first inlet, a second inlet, and an outlet. The three-dimensional transparent rock fracture model has multiple pressure measuring holes, which are respectively arranged in the inlet section, confluence zone, midstream zone, and outlet section of the three-dimensional intersecting fracture channel. The liquid injection unit includes a first liquid storage tank, a second liquid storage tank, a first pulse injection device, and a second pulse injection device; the input terminals of the first pulse injection device and the second pulse injection device are respectively connected to the first liquid storage tank and the second liquid storage tank, and the output terminals of the first pulse injection device and the second pulse injection device are respectively connected to the first inlet and the second inlet; the first pulse injection device and the second pulse injection device are used to deliver fluid to the first inlet and the second inlet respectively in constant injection, in-phase pulse, out-of-phase pulse, phase difference pulse, and single-sided pulse modes. The hydraulic and waste liquid monitoring unit includes a first inlet pressure sensor and a second inlet pressure sensor respectively installed at the first inlet and the second inlet, an outlet pressure sensor and an outlet flow sensor installed at the outlet, multiple external sensors installed at multiple pressure measuring holes, a waste liquid collector connected to the outlet, and a turbidity monitor for detecting the turbidity of the outlet liquid. The visualization monitoring unit includes a workbench, a fluorescence imaging and a three-dimensional imaging system; the fluorescence imaging and three-dimensional imaging system is used to perform dual-color fluorescence tracer imaging, particle image velocimetry, and acquire three-dimensional images of the three-dimensional cross fracture channels in the three-dimensional transparent rock fracture model. The data acquisition and processing unit is connected to the first pulse injection device, the second pulse injection device, the first inlet pressure sensor, the second inlet pressure sensor, the outlet pressure sensor, the outlet flow sensor, multiple external sensors, the turbidity monitor, and the fluorescence imaging and three-dimensional imaging system, respectively, and is used to acquire pulse control signals, pressure signals, flow signals, turbidity signals and image signals under a unified time reference.

[0006] Optionally, the first pulse injection device and the second pulse injection device are flow pulse generators or pressure pulse generators.

[0007] Optionally, the first pulse injection device includes a first programmable injection pump, and the second pulse injection device includes a second programmable injection pump; each pulse cycle includes a high flow rate phase QH with a duration of D·T and a low flow rate phase QL with a duration of (1-D)·T, where T is the period and D is the duty cycle; the first programmable injection pump and the second programmable injection pump form in-phase pulses, out-of-phase pulses, and phase difference pulses by means of common triggering, delayed triggering, or preset different start phases.

[0008] Optionally, the three-dimensional transparent rock fracture model includes an assembled upper model and a lower model. The upper model and the lower model are respectively provided with an upper fracture replication surface and a lower fracture replication surface. The upper fracture replication surface and the lower fracture replication surface are arranged opposite to each other and sealed together to form the three-dimensional intersecting fracture channel.

[0009] Optionally, the upper model and the lower model are mounted and fixed by a model clamping assembly; the model clamping assembly includes a metal clamping frame, an annular sealing groove, a sealing ring, a positioning pin, and fastening bolts; the annular sealing groove is disposed between the upper model and the lower model, and the sealing ring is embedded in the annular sealing groove and located on the periphery of the upper crack replication surface and the lower crack replication surface; the upper model and the lower model are disposed on the metal clamping frame, and the upper model, the lower model, and the metal clamping frame are respectively provided with positioning holes, and the positioning pins are inserted into the positioning holes for positioning and aligning the upper model, the lower model, and the metal clamping frame; the fastening bolts pass through the metal clamping frame, the lower model, and the upper model in sequence to connect and fix the three.

[0010] Optionally, the material of the three-dimensional transparent rock fracture model includes transparent epoxy resin, transparent epoxy acrylate photocurable resin, or transparent polymethyl methacrylate.

[0011] Optionally, the multiple pressure measuring holes are connected to the multiple external sensors via multiple short flexible tubes of the same length and inner diameter.

[0012] Optionally, the fluorescence imaging and three-dimensional imaging system includes a green laser source, a high-speed camera, a filter assembly, and a laser scanning confocal microscope. The filter assembly includes an excitation filter disposed between the three-dimensional transparent rock fracture model and the green laser source, and an emission filter disposed at the incident end of the high-speed camera. The excitation filter and the emission filter are used to construct a green fluorescence channel, and the high-speed camera is used to acquire green fluorescence images. The laser scanning confocal microscope has a built-in red laser source, a red fluorescence channel, and a red fluorescence image acquisition window. The laser scanning confocal microscope is used to acquire red fluorescence images. The laser scanning confocal microscope is also used to scan the three-dimensional transparent rock fracture model at set time intervals and acquire three-dimensional images.

[0013] Optionally, the center wavelength of the excitation filter is 495 nm, and the center wavelength of the emission filter is 520 nm.

[0014] This application also provides a method for rock fracture mineralization experiments, using the rock fracture mineralization experimental apparatus described above, including the following steps: Step 1: Prepare, wash, disperse, filter, degas, and pre-treat the fluorescent tracer particles, non-reactive carrier liquid, sodium sulfate solution, and barium chloride solution at a constant temperature, and perform concentration-grayscale calibration on the fluorescent imaging and three-dimensional imaging system. Step 2: Fabricate and assemble the three-dimensional transparent rock fracture model, and complete the calibration of the image, pressure, flow, and turbidity sensors; Step 3: Inject pure water into the first inlet and the second inlet, check the device's sealing performance, establish a stable flow-pressure differential baseline, and apply a non-reactive pulse to obtain the device's background amplitude attenuation and phase delay; Step 4: Inject the first non-reactive fluid containing red fluorescent tracer particles and the second non-reactive fluid containing green fluorescent tracer particles respectively. Simultaneously acquire fluorescence images and hydraulic data under constant injection, in-phase pulse, out-of-phase pulse, phase difference pulse and single-sided pulse conditions to obtain the concentration field, mixing ratio, mixing index and velocity field of the two fluids. Step 5: Inject sodium sulfate solution and barium chloride solution respectively, and simultaneously acquire high-speed images, confocal 3D images, inlet pressure, fracture segment pressure, outlet pressure, outlet flow rate and turbidity data according to the preset pulse working conditions to obtain precipitation generation area, precipitation distribution, local aperture change, precipitation migration trajectory and blockage evolution. Step 6: While keeping the average flow rate, total injection volume and total molar amount of reactants consistent, change the pulse frequency, amplitude, duty cycle and phase difference, and change the initial fracture aperture, roughness, intersection angle or reactant concentration, and analyze the effects of each parameter on mixing, mineralization and seepage capacity. Step 7: Merge the image, pressure, flow rate, and turbidity data according to a unified timestamp, calculate the local fissure opening, equivalent hydraulic opening, and equivalent permeability, and verify them by mass analysis of the outlet sample and residual sediment in the fissure.

[0015] Beneficial effects: The rock fracture mineralization experimental apparatus and method described in this application, through a first pulse injection device and a second pulse injection device, form in-phase, out-of-phase, phase difference, and unilateral rectangular pulse injections, enabling comparison of the effects of different pulse modes on the oscillation and mixing efficiency of the cross fracture mixing interface under the condition of consistent average injection volume; the three-dimensional transparent rock fracture model is replicated from the three-dimensional morphology of real rock fractures, enabling continuous observation of precipitation formation, detachment, and migration processes while preserving roughness, non-uniformity of aperture, and intersection geometric features; through fluorescence imaging and a three-dimensional imaging system, using dual-color fluorescence tracer and particle image velocimetry technology, the concentration field, local mixing ratio, and velocity field of the two fluids can be obtained simultaneously, and the three-dimensional information of local aperture and sediment layer can be obtained through three-dimensional imaging. Combined with pressure-flow data, the equivalent hydraulic aperture and equivalent permeability can be calculated, enabling quantitative evaluation of the impact of precipitation blockage on seepage capacity; through the data acquisition and processing unit, data such as images, pressure, flow rate, and outlet turbidity are uniformly triggered and processed synchronously, and pressure anomalies can be correlated with events such as precipitation bridging, cluster detachment, channel reopening, and increased outlet particles. This application is applicable to barium sulfate precipitation systems and can also be extended to reaction transport processes such as carbonate mineralization, underground fissure sealing, geothermal scaling, and groundwater remediation. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a rock fracture mineralization experimental device proposed in one embodiment of this application; Figure 2 This is a schematic diagram of the waveforms of in-phase pulses, out-of-phase pulses, phase difference pulses, and unilateral pulses generated by the first pulse injection device and the second pulse injection device in the rock fracture mineralization experimental apparatus proposed in an embodiment of this application. Figure 3 This is an exploded view of a three-dimensional transparent rock fracture model in a rock fracture mineralization experimental apparatus proposed in an embodiment of this application; Figure 4 This is a schematic diagram of the three-dimensional cross fracture channel structure of the three-dimensional transparent rock fracture model in a rock fracture mineralization experimental device proposed in an embodiment of this application; Figure 5 This is a diagram showing the acquisition relationship of a multi-channel synchronous data acquisition system in a rock fracture mineralization experimental apparatus according to an embodiment of this application; Figure 6This is a flowchart of data processing for a rock fracture mineralization experimental apparatus proposed in one embodiment of this application.

[0018] Explanation of reference numerals in the attached figures: 1. First reservoir; 2. Second reservoir; 3. First programmable injection pump; 4. Second programmable injection pump; 5. First inlet pressure sensor; 6. Second inlet pressure sensor; 7. Three-dimensional transparent rock fracture model; 71a. Upper model; 71b. Lower model; 72a. First inlet; 72b. Second inlet; 72c. Outlet; 73. Sealing ring; 74. Annular sealing groove; 75. Positioning pin; 76. Metal clamping frame; 77. Fastening bolt; 7 8a. Upper fracture replication surface; 78b. Lower fracture replication surface; 79. Pressure measuring hole; 79a. Short flexible tube; 79b. External sensor; 8. Laser scanning confocal microscope; 9. Worktable; 10. Green laser source; 11. High-speed camera; 12. Outlet pressure sensor; 13. Outlet flow sensor; 14. Communication cable; 15. Multi-channel synchronous data acquisition system; 16. Computer; 17. Flexible tube; 18. Waste liquid collector; 19. Turbidity monitor. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] In related technologies, fracture reaction transport experiments often employ constant pressure boundaries, making it difficult to simulate the periodic pressurization or intermittent injection conditions considered in actual engineering. Among these, a small number of pulse injection studies primarily focus on improving injection capacity or inducing crack propagation, neglecting to consider the visualization of the reaction process between the two reaction liquids within the fracture and the mineralization process inside the fracture. Therefore, it is difficult to clarify the influence mechanism of pulse pressure on the degree of solution mixing, reaction hotspots, and the migration trajectory of the resulting precipitates.

[0021] In view of this, embodiments of this application provide a rock fracture mineralization experimental apparatus and method.

[0022] See Figure 1 An experimental apparatus for rock fracture mineralization, comprising: A three-dimensional transparent rock fracture model 7 has a three-dimensional intersecting fracture channel with a first inlet 72a, a second inlet 72b, and an outlet 72c inside. The three-dimensional transparent rock fracture model 7 has a plurality of pressure measuring holes 79, which are respectively arranged in the inlet section, confluence area, midstream area, and outlet section of the three-dimensional intersecting fracture channel. The liquid injection unit includes a first liquid storage tank 1, a second liquid storage tank 2, a first pulse injection device, and a second pulse injection device. The input terminals of the first pulse injection device and the second pulse injection device are respectively connected to the first liquid storage tank 1 and the second liquid storage tank 2, and the output terminals of the first pulse injection device and the second pulse injection device are respectively connected to the first inlet 72a and the second inlet 72b. The first pulse injection device and the second pulse injection device are used to deliver fluid to the first inlet 72a and the second inlet 72b respectively in constant injection, in-phase pulse, out-of-phase pulse, phase difference pulse, and single-sided pulse modes. The hydraulic and waste liquid monitoring unit includes a first inlet pressure sensor 5 and a second inlet pressure sensor 6 respectively installed at the first inlet 72a and the second inlet 72b, an outlet pressure sensor 12 and an outlet flow sensor 13 installed at the outlet 72c, multiple external sensors 79b installed at multiple pressure measuring holes 79, a waste liquid collector 18 connected to the outlet 72c, and a turbidity monitor 19 for detecting the turbidity of the outlet liquid. The visualization monitoring unit includes a workbench 9 and a fluorescence imaging and three-dimensional imaging system; the fluorescence imaging and three-dimensional imaging system is used to perform dual-color fluorescence tracer imaging, particle image velocimetry, and acquire three-dimensional images of the three-dimensional cross fracture channels in the three-dimensional transparent rock fracture model 7. The data acquisition and processing unit is connected to the first pulse injection device, the second pulse injection device, the first inlet pressure sensor 5, the second inlet pressure sensor 6, the outlet pressure sensor 12, the outlet flow sensor 13, multiple external sensors 79b, the turbidity monitor 19, and the fluorescence imaging and three-dimensional imaging system, respectively, and is used to acquire pulse control signals, pressure signals, flow signals, turbidity signals and image signals under a unified time reference.

[0023] In this embodiment, the three-dimensional transparent rock fracture model 7 is a replica of the three-dimensional morphology of a real rock fracture, and its transparent structure facilitates visualization during experiments. The model's interior forms a three-dimensional intersecting fracture channel with a first inlet 72a, a second inlet 72b, and an outlet 72c. Experimental studies are conducted by injecting two different fluids into the first inlet 72a and the second inlet 72b, respectively. Pressure measuring holes 79 are respectively provided at the inlet section, confluence zone, midstream zone, and outlet section of the three-dimensional intersecting fracture channel to facilitate connection to external sensors 79b to obtain pressure data at different locations. For ease of description, the overall flow direction from the first inlet 72a and the second inlet 72b to the outlet 72c is defined as the length direction, the direction between the upper and lower fracture replica surfaces is defined as the opening direction, and the direction perpendicular to the length direction and the opening direction is defined as the width direction.

[0024] The first storage tank 1 is connected to the first pulse injection device via a chemically resistant input pipe. The outlet 72c of the first pulse injection device is connected in sequence to the first inlet pressure sensor 5 and the first inlet 72a via the input pipe. The second storage tank 2 is connected to the first pulse injection device via another independent chemically resistant input pipe. The outlet 72c of the first pulse injection device is connected in sequence to the second inlet pressure sensor 6 and the second inlet 72b. The first storage tank 1 and the second storage tank 2 are used to store the first fluid and the second fluid used in the experiment, respectively. The first pulse injection device and the second pulse injection device are used to inject the two fluids into the first inlet 72a and the second inlet 72b in the form of independent pulses, respectively. The two injection pipelines are independent of each other and only come into contact in the cross fracture area after entering the three-dimensional transparent rock fracture model 7, so as to avoid premature reaction in the external pipeline. Through the two independent pulse injection devices, various injection modes such as constant injection, in-phase pulse, out-of-phase pulse, phase difference pulse, and single-sided pulse can be realized to meet the simulation requirements of different experimental conditions and to conform to the working conditions such as periodic pressurization and intermittent injection in actual engineering.

[0025] In the hydraulic and waste liquid monitoring unit, the first inlet pressure sensor 5 and the second inlet pressure sensor 6 monitor the injection pressure of the two inlets in real time, respectively. The outlet pressure sensor 12 and the outlet flow sensor 13 at the outlet 72c monitor the pressure and outflow of the outlet 72c, respectively. Multiple external sensors 79b arranged at pressure measuring holes 79 in different areas can accurately obtain the pressure at different positions of the three-dimensional cross fracture channel. The waste liquid collector 18 collects and processes the waste liquid after the experiment and provides it for subsequent ion concentration and precipitation quality analysis. The detection probe of the turbidity monitor 19 is set in the inlet area of ​​the waste liquid collector 18 to continuously record the turbidity changes caused by suspended precipitate particles in the outlet liquid.

[0026] In the visualization monitoring unit, the three-dimensional transparent rock fracture model 7 is fixedly placed on the workbench 9 to ensure the stability of the imaging position. Through the fluorescence imaging and three-dimensional imaging system, dual-color fluorescence tracer imaging, particle image velocimetry and three-dimensional image acquisition can be realized simultaneously. It can simultaneously obtain the concentration field distribution, motion velocity and three-dimensional distribution information of fluid and sediment inside the fracture.

[0027] The data acquisition and processing unit is connected to the aforementioned pressure sensors, flow sensors, turbidity monitor 19, fluorescence imaging and three-dimensional imaging system respectively, and triggers and processes pressure, flow, outlet 72c turbidity and images in a unified manner to ensure that various signals can correspond to each other in the time dimension and avoid data analysis errors caused by time asynchrony.

[0028] Optionally, the first pulse injection device and the second pulse injection device are flow pulse generators or pressure pulse generators.

[0029] Specifically, the first and second pulse injection devices can be either flow pulse generators or pressure pulse generators. The flow pulse generator can be a programmable high-precision syringe pump, whose direct control quantity is the syringe plunger speed or instantaneous flow rate, while the inlet pressure is the response quantity resulting from the combined effects of gap resistance, tubing compliance, syringe deformation, and air bubble content. The pressure pulse generator can be a combination of a multi-channel microfluidic pressure controller, a media-isolated high-speed solenoid valve, and an electromagnetic proportional regulating valve to directly apply pressure pulses. It can be combined with the measured signals from the first inlet pressure sensor 5 and the second inlet pressure sensor 6 to form a closed-loop control.

[0030] Optionally, the first pulse injection device includes a first programmable injection pump 3, and the second pulse injection device includes a second programmable injection pump 4; each pulse cycle includes a high flow stage QH with a duration of D·T and a low flow stage QL with a duration of (1-D)·T, where T is the period and D is the duty cycle; the first programmable injection pump 3 and the second programmable injection pump 4 form in-phase pulses, out-of-phase pulses, and phase difference pulses by means of common triggering, delayed triggering, or preset different start stages.

[0031] In this embodiment, a programmable high-precision syringe pump is used as the flow pulse generator. A PHD ULTRA type programmable high-precision syringe pump with method program editing and external triggering functions can be selected, or other models with the same functions can be used.

[0032] Before the experiment, a cyclic program was established for each pump: program segment A ran at a high flow rate QH for D·T, program segment B ran at a low flow rate QL for (1-D)·T, and then returned to program segment A and cyclically repeated N times. If QL was set to zero, a start-stop rectangular pulse was formed; if QL was greater than zero, a rectangular pulse with a reference flow rate was formed.

[0033] like Figure 2 As shown, the in-phase pulse is obtained by simultaneously sending TTL start signals to both injection pumps and executing the same program; the out-of-phase pulse is obtained by starting the second programmable injection pump 4 from a low-flow program segment, or by delaying its start relative to the first programmable injection pump 3 by T / 2; the phase difference pulse is obtained by delaying the start of the second programmable injection pump 4. Start-up is achieved; a single-sided pulse causes the first programmable syringe pump 3 to execute a rectangular program while the second programmable syringe pump 4 maintains a constant flow rate. To eliminate differences in total injection volume, all operating conditions preferably meet the same average flow rate. .

[0034] In addition to rectangular waves, sine waves, triangular waves, trapezoidal waves, stepped waves, pseudo-random binary sequences, or combined pulses can also be used, and the amplitude, frequency, duty cycle, and phase difference can still be controlled.

[0035] Optionally, the three-dimensional transparent rock fracture model 7 includes an integrated upper model 71a and a lower model 71b. The upper model 71a and the lower model 71b are respectively provided with an upper fracture replication surface 78a and a lower fracture replication surface 78b. The upper fracture replication surface 78a and the lower fracture replication surface 78b are arranged opposite to each other and sealed together to form the three-dimensional intersecting fracture channel.

[0036] In this embodiment, the main body of the three-dimensional transparent rock fissure model 7 is assembled from two transparent models, upper and lower. The bottom surface of the upper model 71a is provided with an upper fissure replication surface 78a, and the top surface of the lower model 71b is provided with a lower fissure replication surface 78b. Both the upper fissure replication surface 78a and the lower fissure replication surface 78b are replicated from the fissure surface of real rock. After the two replication surfaces are arranged opposite each other and sealed and assembled, a three-dimensional cross fissure channel with the same internal morphology as the real rock can be formed. While ensuring the restoration of the geometric features of the real fissure, it also meets the observation requirements of transparent visualization.

[0037] Optionally, the upper model 71a and the lower model 71b are mounted and fixed by a model clamping assembly; the model clamping assembly includes a metal clamping frame 76, an annular sealing groove 74, a sealing ring 73, a positioning pin 75, and a fastening bolt 77; the annular sealing groove 74 is disposed between the upper model 71a and the lower model 71b, and the sealing ring 73 is embedded in the annular sealing groove 74 and located around the upper crack replication surface 78a and the lower crack replication surface 78b; the upper model Model 71a and the lower model 71b are mounted on the metal clamping frame 76. Positioning holes are provided in the upper model 71a, the lower model 71b and the metal clamping frame 76 respectively. Positioning pins 75 are inserted into the positioning holes to position and align the upper model 71a, the lower model 71b and the metal clamping frame 76. Fastening bolts 77 pass through the metal clamping frame 76, the lower model 71b and the upper model 71a in sequence to connect and fix the three together.

[0038] See Figure 3 and Figure 4 The upper model 71a and the lower model 71b are mounted on a metal clamping frame 76, which supports and positions the upper and lower models. An annular sealing groove 74 is located between the upper model 71a and the lower model 71b, and a sealing ring 73 is embedded in the annular sealing groove 74, surrounding the outer sides of the upper fracture replication surface 78a and the lower fracture replication surface 78b. After the upper and lower models are assembled and pressed together, the fracture channel can be sealed to prevent leakage during the experiment. The metal clamping frame 76 is provided with positioning holes that engage with positioning pins 75. Correspondingly, corresponding positioning holes are also provided in the upper model 71a and the lower model 71b. The positioning holes are located in the non-fracture flow area on the periphery of the upper and lower fracture replication surfaces to avoid damaging the structure of the fracture channel. Positioning pins 75 are inserted into corresponding positioning holes to align and position the upper model 71a, lower model 71b, and metal clamping frame 76, ensuring precise mold fitting of the replicated crack surface and preventing misalignment from affecting the realism of the crack structure. Bolt holes for fastening bolts 77 are also provided on the upper model 71a, lower model 71b, and metal clamping frame 76. These bolt holes are located in the non-crack flow area surrounding the upper and lower crack replication surfaces. By passing the fastening bolts 77 sequentially through the bolt holes in the metal clamping frame 76, lower model 71b, and upper model 71a, the three components are fixed together, ensuring the overall stability of the model structure.

[0039] Optionally, the material of the three-dimensional transparent rock fissure model 7 includes transparent epoxy resin, transparent epoxy acrylate light-cured resin, or transparent polymethyl methacrylate.

[0040] In some embodiments, the main material of the three-dimensional transparent rock fracture model 7 may be selected from transparent epoxy resin, epoxy acrylate light-cured resin, transparent polymethyl methacrylate, transparent polycarbonate, or other materials that meet the requirements of chemical corrosion resistance and light transmission.

[0041] In actual production, the three-dimensional transparent rock fissure model 7 can be manufactured using either a natural fissure casting method or a three-dimensional scanning-printing method. This embodiment preferably uses the three-dimensional scanning-printing method, employing transparent photocurable epoxy acrylate resin as the main body of the model; polyvinyl alcohol can be used as the printing support material, which is removed with water after printing. The specific method is as follows: a removable revealing agent is sprayed onto the upper and lower fissure surfaces of the real rock; point cloud data is collected using a three-dimensional surface topography scanner; outlier removal, hole repair, coordinate unification, upper and lower surface registration, and triangulation are performed; a solid model is established based on the initial opening and intersection angle of the target, and the first inlet 72a, second inlet 72b, outlet 72c, pressure measuring hole 79, annular sealing groove 74, positioning holes, and bolt holes are designed; the model is imported into a transparent resin three-dimensional printing device to print the upper and lower models; after printing, the optical observation surface is progressively ground and polished, and residual resin is cleaned with deionized water.

[0042] During assembly of the upper and lower models, first, embed the sealing ring 73 into the annular sealing groove 74, and check that the sealing ring 73 is free from twisting, damage, or particle adhesion. Insert the positioning pin 75 into the positioning hole of the metal clamping frame 76, place the lower model 71b onto the metal clamping frame 76, and ensure that the positioning hole in the lower model 71b fits onto the positioning pin 75 to restrict its planar position. Similarly, place the upper model 71a onto the lower model 71b, and ensure that the positioning hole in the upper model 71a fits onto the positioning pin 75, so that the upper model 71a... The upper fracture replication surface 78a and the lower fracture replication surface 78b are aligned according to the scanning registration relationship. Then, fastening bolts 77 are installed, sequentially passing through the corresponding bolt holes in the lower model 71b, the metal clamping frame 76, and the upper model 71a to clamp them together to form a detachable, integrated structure. Tightening is performed in a diagonal, tiered manner, increasing the torque by the same small amount each time, until the sealing ring 73 is uniformly compressed and the gaps on all sides are consistent, reducing model warping and the impact of excessive local preload on the initial opening. Corrosion-resistant joints are used at the first inlet 72a, the second inlet 72b, and the outlet 72c, and are sealed to the model using gaskets or threaded sealing materials.

[0043] Optionally, the plurality of pressure measuring holes 79 are respectively connected to the plurality of external sensors 79b through a plurality of short flexible tubes 79a of the same length and inner diameter.

[0044] In this embodiment, pressure measuring holes 79 are formed in the upper model 71a or the lower model 71b, extending from the outer surface of the model to the wall of the three-dimensional fracture flow channel. The inner port of each pressure measuring hole 79 is flush with the fracture wall and does not protrude into the fracture flow channel. The outer end of each pressure measuring hole 79 is connected to an external sensor 79b through a short flexible tube 79a of the same length and inner diameter. The short flexible tube 79a does not extend into the fracture flow channel. The consistent length and inner diameter of the multiple short flexible tubes 79a ensure consistent dynamic response at each pressure measuring point. The external sensor 79b is preferably a voltage output type high-precision gauge pressure sensor or differential pressure sensor. Its main body is fixed outside the model and does not enter the fracture flow channel, which reduces the disturbance of the probe to the local flow field.

[0045] Optionally, the first inlet pressure sensor 5 and the second inlet pressure sensor 6 are preferably installed close to the first inlet 72a and the second inlet 72b to reduce the influence of pressure drop in the long pipeline on the measured inlet pressure. Both the first inlet pressure sensor 5 and the second inlet pressure sensor 6 can be high-precision pressure transmitters with outputs of 0–10 V, ±5 V, or 4–20 mA. Their main function is to record the actual pressure pulses entering the fracture and to distinguish the pressure response caused by changes in the set flow rate of the injection pump and the hydraulic resistance of the fracture.

[0046] Optionally, the outlet pressure sensor 12 and outlet flow sensor 13 are connected to the waste liquid collector 18 via hose 17. The turbidity monitor 19 can be an online flow-through turbidity sensor, or the detection probe of the turbidity monitor 19 can be placed in the stable inlet zone of the waste liquid collector 18. The waste liquid collector 18 is a corrosion-resistant sealed container and is equipped with a manual sampling port. Barium chloride and soluble barium salts are toxic; all reaction waste liquids should be collected separately and must not be directly discharged. After the experiment, particulate barium sulfate can be obtained through filtration, and the Ba in the filtrate can be... 2+ and SO4 2- Offline analysis was performed to verify the amount of sediment retained in the fracture.

[0047] Optionally, the fluorescence imaging and three-dimensional imaging system includes a green laser source 10, a high-speed camera 11, a filter assembly, and a laser scanning confocal microscope 8. The filter assembly includes an excitation filter disposed between the three-dimensional transparent rock fissure model 7 and the green laser source 10, and an emission filter disposed at the incident end of the high-speed camera 11. The excitation filter and the emission filter are used to construct a green fluorescence channel, and the high-speed camera 11 is used to acquire green fluorescence images. The laser scanning confocal microscope 8 has a built-in red laser source, a red fluorescence channel, and a red fluorescence image acquisition window. The laser scanning confocal microscope 8 is used to acquire red fluorescence images. The laser scanning confocal microscope 8 is also used to scan the three-dimensional transparent rock fissure model 7 at set time intervals and acquire three-dimensional images.

[0048] Specifically, a three-dimensional transparent rock fracture model 7 is fixed on a worktable 9. A laser scanning confocal microscope 8 is positioned above or to the side of the three-dimensional transparent rock fracture model 7, with its scanning area covering the cross-mixing zone of the first inlet 72a and the second inlet 72b, as well as the downstream precipitation-sensitive zone. A green laser source 10 is positioned below the transparent window of the worktable 9 or on the other side of the three-dimensional transparent rock fracture model 7. A high-speed camera 11 is mounted on a rigid adjustable bracket and aligned with the observation area of ​​the three-dimensional transparent rock fracture model 7. This arrangement is used to obtain images of tracer particles, mixing interfaces, precipitation formation, and precipitation cluster migration without contact with the fluid.

[0049] When conducting mineralization research using the device provided in this embodiment, it is necessary to perform non-reactive dual-channel tracer experiments, low-concentration pre-reaction experiments, and formal mineralization reaction experiments. The non-reactive tracer experiments employ red and green fluorescent tracer particles with similar particle size and density. The red fluorescent tracer particles are polystyrene microspheres pre-labeled with Rhodamine B fluorescent dye, while the green fluorescent tracer particles are polystyrene microspheres pre-labeled with FITC (isothiocyanate) fluorescein. Both types of microspheres maintain consistent particle size and density and are centrifuged, washed, resuspended in deionized water, and ultrasonically dispersed before use to reduce free dye and particle aggregation. In the mineralization reaction experiment, the first reaction solution is a sodium sulfate solution of 0.01 mol / L to 1.00 mol / L, and the second reaction solution is a barium chloride solution of 0.01 mol / L to 1.00 mol / L. Preferably, the concentration of both solutions is 0.01 mol / L in the pre-reaction experiment and 0.10 mol / L in the formal mineralization experiment. They are mixed at equimolar flow rates to generate barium sulfate precipitate.

[0050] An excitation filter with a center wavelength of approximately 495 nm is installed between the green laser source 10 and the three-dimensional transparent rock fracture model 7, and an emission filter with a center wavelength of approximately 520 nm is installed in front of the high-speed camera 11. These filters are used to acquire FITC green microspheres and form a continuous image sequence for PIV (Particle Image Velocimetry) calculation. The red fluorescence channel does not use a separate external red laser source; instead, it utilizes the 543 nm / 561 nm laser channel built into the laser scanning confocal microscope 8 as the excitation source, and acquires Rhodamine B-type red microspheres through its corresponding red emission detection window. Since the 495 / 520 nm filter combination is only applicable to the FITC green channel and cannot effectively acquire the red channel, this embodiment employs a separate acquisition method where the high-speed camera 11 acquires the green channel and the laser scanning confocal microscope 8 acquires the red channel.

[0051] The high-speed camera 11 acquires continuous image pairs through PIV synchronous triggering. The frame rate during the normal flow phase can be set to 20-100 frames per second, while it can be increased to 100-1000 frames per second during pulse switching or rapid particle migration phases. The specific frame rate is determined based on the pulse frequency and particle displacement within the field of view, ensuring that the particle displacement in adjacent images is within a reasonable range calculated by PIV.

[0052] The laser scanning confocal microscope 8 is also used to periodically scan the three-dimensional transparent rock fracture model 7 and acquire three-dimensional images. The scanning interval is 30s to 120s, preferably a z-axis layer scan is performed every 60s. The layer spacing and scanning range of each scan are determined according to the initial fracture opening and the expected precipitation thickness.

[0053] Optionally, the data acquisition and processing unit includes a multi-channel synchronous data acquisition system 15, a communication cable 14, and a computer 16. For example... Figure 5 As shown, the multi-channel synchronous data acquisition system 15 is connected to the first programmable injection pump 3, the second programmable injection pump 4, the first inlet pressure sensor 5, the second inlet pressure sensor 6, the outlet pressure sensor 12, the outlet flow sensor 13, the external sensor 79b, the high-speed camera 11, the laser scanning confocal microscope 8, and the turbidity monitor 19 via communication cables 14, and acquires pulse control signals, pressure signals, flow signals, image signals, and turbidity signals under a unified time reference.

[0054] The multi-channel synchronous data acquisition system 15 includes a modular data acquisition chassis, a synchronous analog input module, and a digital trigger module. The synchronous analog input module acquires voltage or current signals output from each pressure sensor, outlet flow sensor 13, and turbidity monitor 19. The digital trigger module sends a unified trigger signal to two programmable injection pumps, a high-speed camera 11, and a laser scanning confocal microscope 8. The computer 16 performs time synchronization, particle image velocimetry, mixing zone identification, sedimentation zone segmentation, fracture local aperture identification, pressure-flow feature extraction, and multi-source data fusion on the acquired data, outputting mixing ratio, mineralization intensity, equivalent hydraulic aperture, equivalent permeability, sediment migration trajectory, sedimentation location, and degree of blockage.

[0055] Specifically, the multi-channel synchronous data acquisition system 15 is an existing modular data acquisition device. In a specific configuration that is not limiting, the multi-channel synchronous data acquisition system 15 uses a CompactDAQ class eight-slot USB data acquisition chassis, configured with a sixteen-channel synchronous voltage input module and a 5V TTL digital input / output module. The synchronous voltage input module is used to receive voltage signals from the first inlet pressure sensor 5, the second inlet pressure sensor 6, the outlet pressure sensor 12, the outlet flow sensor 13, each external sensor 79b, and the turbidity monitor 19; for 4-20 mA output instruments, the signals can be acquired after conversion by a precision sampling resistor or current input module. The digital input / output module sends the same TTL start signal to the first programmable syringe pump 3, the second programmable syringe pump 4, and the high-speed camera 11 at the start of the experiment, and receives camera exposure or frame synchronization signals. The laser scanning confocal microscope 8 sends scanning commands from the computer 16 at preset 60s intervals, and writes the start and end times of each scan into a data file.

[0056] The multi-channel synchronous data acquisition system 15 is connected to the computer 16 via USB or Ethernet. The computer 16 can run LabVIEW, Python, MATLAB, or similar software to perform real-time display, data storage, and experimental status assessment. Figure 6 As shown, the data processing flow is as follows: time synchronization of pressure, flow, image and waste liquid data; data and image preprocessing; identification of mixing zone, segmentation of sedimentation zone, identification of local fissure opening, extraction of pressure-flow characteristics and measurement of sediment mass; finally, multi-source data fusion is performed to output mixing state, mineralization reaction intensity, fissure seepage capacity, sedimentation location and degree of blockage.

[0057] Computer 16 first aligns the pump program segment switching markers, pressure, flow rate, turbidity, and image frames according to a unified timestamp. It then performs dark field subtraction, flat field correction, lens distortion correction, and image registration on the original image; based on the calibration curves of the red and green channels, it converts grayscale to relative concentration. and And calculate the local mixing fraction. The mixing index can be determined based on... The spatial standard deviation is normalized relative to the standard deviation of the completely separated state, so that its value ranges from 0 to 1, representing from completely separated to fully mixed.

[0058] The PIV module divides adjacent images into query windows and calculates the velocity vector through cross-correlation. The velocity gradient and vorticity were analyzed, and the velocity changes in the convergence zone, low-speed zone, and mainstream zone were statistically analyzed. By comparing the mixing index, interface oscillation amplitude, and velocity field under in-phase, out-of-phase, phase difference, and single-pulse conditions, the enhancing or inhibiting effect of the pulse on mixing can be determined.

[0059] In the mineralization reaction images, barium sulfate precipitation regions were identified through background subtraction, threshold segmentation, and morphological processing. Precipitation coverage, frontal position, centroid coordinates, local area growth rate, and cluster number were calculated. Target matching or optical flow tracking was performed on precipitation clusters in continuous images to obtain the trajectory, velocity, and residence time of clusters moving downstream from the junction area.

[0060] Z-axis tomographic images from a laser scanning confocal microscope 8 were used to reconstruct the upper fracture replication surface 78a, the lower fracture replication surface 78b, and the surface of the sedimentary layer. This was achieved using an initial local aperture. Based on this, obtain the remaining overcurrent opening at time t. The local opening changes as follows When sediment occupies space A negative value indicates that the precipitate has partially dissolved or been washed away. It can rebound.

[0061] The overall seepage capacity of the fracture is obtained by the first inlet pressure sensor 5, the second inlet pressure sensor 6, the external sensor 79b, the outlet pressure sensor 12, and the outlet flow sensor 13.

[0062] When the differential pressure in a certain segment continuously increases, the local opening in the corresponding area decreases, and the sediment coverage increases, sediment blockage is determined to have occurred in that segment. When the differential pressure in a segment suddenly decreases, the clusters in the image disappear or move downstream, and the outlet turbidity increases simultaneously, sediment cluster detachment and migration are determined to have occurred. By using the above multi-source criteria, misjudgments caused by relying solely on a single pressure or a single image can be reduced.

[0063] The rock fracture mineralization experimental apparatus provided in this embodiment has at least the following advantages compared with the prior art: (1) By using two independent programmable high-precision injection pumps to generate in-phase, out-of-phase, phase difference and single-sided rectangular pulses, it is possible to compare the effects of different pulse modes on the oscillation and mixing efficiency of the cross-crack mixing interface under the condition that the average injection volume is consistent. (2) By combining the green laser light source 10, the high-speed camera 11 and the laser scanning confocal microscope 8, red and green dual-channel fluorescence tracing and particle image velocimetry can be realized. The concentration field, local mixing ratio and velocity field of the two fluids can be obtained at the same time, avoiding the judgment of the mixing state based solely on the final color or the outlet 72c concentration. Furthermore, the laser scanning confocal microscope 8 can obtain the local opening and three-dimensional information of the sedimentation layer. Combined with pressure-flow data, the equivalent hydraulic opening and equivalent permeability can be calculated, which can quantitatively evaluate the impact of sedimentation blockage on the seepage capacity. (3) The three-dimensional transparent rock fracture model 7 is a copy of the three-dimensional morphology of real rock fractures and is a transparent structure. It can achieve continuous observation of precipitation generation, shedding and migration processes while preserving roughness, non-uniformity of aperture and intersection geometric features. (4) The partition pressure response is obtained through the flush pressure measuring hole 79 and the external sensor 79b of the model, without the sensor body extending into the flow channel, thereby reducing the interference of the measuring device on the flow field and nucleation process; (5) Through the multi-channel synchronous data acquisition system 15, communication cable 14 and computer 16, video, confocal image, pressure, flow and outlet turbidity are triggered and processed synchronously in a unified manner, and pressure abnormality can be correlated with events such as sedimentation bridging, cluster shedding, channel reopening and increase in outlet particles.

[0064] This application also provides a method for rock fracture mineralization experiments, using the rock fracture mineralization experimental apparatus described above, including the following steps: Step 1: Prepare, wash, disperse, filter, degas, and pre-treat the fluorescent tracer particles, non-reactive carrier liquid, sodium sulfate solution, and barium chloride solution at a constant temperature, and perform concentration-grayscale calibration on the fluorescent imaging and three-dimensional imaging system.

[0065] Step 1 specifically includes the following steps: Step 11: Prepare the first non-reactive fluid and the second non-reactive fluid. The two carrier fluids use the same deionized water-based solution, and the density and viscosity are kept close by adding inert salts or viscosity modifiers. Rhodamine B-type red fluorescent microspheres and FITC green fluorescent microspheres are added respectively.

[0066] Step 12: The two types of fluorescent microspheres were centrifuged, washed, resuspended, and ultrasonically dispersed to determine their particle size distribution and sedimentation stability.

[0067] Step 13: Prepare the mineralization reaction solution using analytical grade anhydrous sodium sulfate and barium chloride dihydrate. In the low-concentration pre-reaction experiment, prepare 0.01 mol / L sodium sulfate solution and 0.01 mol / L barium chloride solution respectively; in a preferred embodiment of the formal mineralization reaction experiment, prepare 0.10 mol / L sodium sulfate solution and 0.10 mol / L barium chloride solution respectively. Both solutions are filtered, degassed, and kept at a constant temperature of 25±1 °C.

[0068] Step 14: When simultaneous rate measurement is required in the reaction experiment, low-concentration inert fluorescent microspheres with compatibility verification can be added to both reaction solutions, and a parallel control group without microspheres can be set up to confirm that the tracer microspheres do not significantly change the nucleation time, precipitation quality or particle size of barium sulfate.

[0069] Step 2: Fabricate and assemble the three-dimensional transparent rock fracture model, and complete the calibration of the image, pressure, flow, and turbidity sensors.

[0070] Step 2 specifically includes the following steps: Step 21: Perform a three-dimensional scan of the surface of the upper and lower fissures of the real rock, and complete point cloud denoising, registration and meshing; design the intersection angle, initial average aperture and pressure measurement hole position according to the research objectives.

[0071] Step 22: Import the digital model into the transparent resin 3D printing equipment, and use transparent light-curing epoxy acrylate resin to print the upper and lower models; when using polyvinyl alcohol as the support material, thoroughly wash away the support with water after printing and complete secondary curing and polishing.

[0072] Step 23: Install the sealing ring into the annular sealing groove, complete the registration using the positioning pin, place the upper and lower models in the metal clamping frame, and tighten the fastening bolts in a diagonal sequence; connect the joints at the first inlet, the second inlet, and the outlet.

[0073] Step 24: Connect each pressure measuring hole to external sensors through short flexible tubes, and install the first inlet pressure sensor, the second inlet pressure sensor, the outlet pressure sensor, the outlet flow sensor, the turbidity monitor, the high-speed camera, the green laser light source, and the laser scanning confocal microscope.

[0074] Step 25: Calibrate each pressure sensor using a static pressure source, calibrate the outlet flow sensor using a weighing method, and calibrate the turbidity monitor using a standard barium sulfate suspension.

[0075] Step 3: Inject pure water into the first inlet and the second inlet, check the device's sealing performance, establish a stable flow-pressure differential baseline, and apply a non-reactive pulse to obtain the device's background amplitude attenuation and phase delay.

[0076] Step 3 specifically includes the following steps: Step 31: Slowly inject degassed pure water into the two injection lines and the three-dimensional transparent rock fracture model to expel all visible air bubbles. Close the outlet and gradually increase the inlet pressure. Check for leaks at the sealing rings, joints, short hoses, and sensor connections.

[0077] Step 32: With the outlet open, set several constant flow rates, record the first inlet pressure, second inlet pressure, pressure of each segment, outlet pressure, and outlet flow rate to establish the initial... relation.

[0078] Step 33: Perform the following steps under pure water conditions. Figure 3 The pulse program shown records the pump program signal and the response of each measuring point, and obtains the pulse rise time, amplitude attenuation, phase delay and recovery time of the device itself, providing a baseline for subsequent identification of abnormalities caused by precipitation.

[0079] Step 4: Inject the first non-reactive fluid containing red fluorescent tracer particles and the second non-reactive fluid containing green fluorescent tracer particles respectively. Simultaneously acquire fluorescence images and hydraulic data under constant injection, in-phase pulse, out-of-phase pulse, phase difference pulse and single-sided pulse conditions to obtain the concentration field, mixing ratio, mixing index and velocity field of the two fluids.

[0080] Step 4 specifically includes the following steps: Step 41: Add the first non-reactive fluid containing red fluorescent microspheres to the first storage tank, and add the second non-reactive fluid containing green fluorescent microspheres to the second storage tank, confirming that no chemical reaction occurs between the two fluids.

[0081] Step 42: Turn on the green laser source and high-speed camera, install the 495 nm excitation filter and the 520 nm emission filter, and acquire green tracer images; use the red channel of the laser scanning confocal microscope to acquire red tracer images.

[0082] Step 43: Perform constant injection, in-phase pulse, out-of-phase pulse, phase difference pulse and single-sided pulse experiments in sequence; keep the average flow rate, total injection volume and experimental time consistent for each operating condition.

[0083] Step 44: The multi-channel synchronous data acquisition system simultaneously records the pump program, inlet pressure, segment pressure, outlet pressure, outlet flow rate, and image frames; the computer obtains fluid velocity, red-green concentration field, local mixing ratio, mixing index, interface oscillation amplitude, and mixing zone migration speed through PIV and dual-channel concentration calibration.

[0084] Step 45: Compare the mixing index, peak velocity, low-velocity range, and pressure fluctuations in the confluence and downstream regions under different pulse patterns to determine the enhancing or inhibiting effect of the pulse on mixing and flow velocity.

[0085] Step 5: Inject sodium sulfate solution and barium chloride solution respectively, and simultaneously acquire high-speed images, confocal 3D images, inlet pressure, fracture segment pressure, outlet pressure, outlet flow rate and turbidity data according to the preset pulse operating conditions to obtain precipitation formation area, precipitation distribution, local opening changes, precipitation migration trajectory and blockage evolution.

[0086] Step 5 specifically includes: Step 51: Conduct a low-concentration mineralization pre-reaction experiment.

[0087] Step 511: Add 0.01 mol / L sodium sulfate solution to the first storage tank and 0.01 mol / L barium chloride solution to the second storage tank. Determine the initial precipitation visibility, nucleation time and outlet turbidity range using a low flow rate and constant injection method.

[0088] Step 512: Turn on the high-speed camera to continuously shoot, and use the laser scanning confocal microscope to perform a z-axis scan every 60 seconds to check whether the precipitation area, precipitation layer thickness and remaining crack opening can be stably identified.

[0089] Step 513: Check whether the outlet flow sensor and turbidity monitor are experiencing particle retention or blockage, and determine the flow range, sampling frequency, camera frame rate and confocal scanning parameters for the formal experiment.

[0090] Step 52: Conduct a formal mineralization reaction experiment.

[0091] Step 521: Add 0.10 mol / L sodium sulfate solution to the first storage tank, and add 0.10 mol / L barium chloride solution to the second storage tank; inject the two solutions at an equimolar average flow rate, so that Ba... 2+ With SO4 2- The average molar ratio is 1:1.

[0092] Step 522: Set up the constant injection reference group and the in-phase, out-of-phase, phase difference, and single-sided pulse groups. Pre-set QH, QL, T, D, and [other parameters] for each group. And ensure that the average flow rate, experimental time, total injection volume and total molar amount of reactants are consistent.

[0093] Step 523: Start the multi-channel synchronous data acquisition system, and simultaneously start the two syringe pumps and the high-speed camera by the digital trigger signal; continuously record the signals of the first inlet pressure sensor, the second inlet pressure sensor, the external sensor, the outlet pressure sensor, the outlet flow sensor and the turbidity monitor.

[0094] Step 524: A high-speed camera is used to acquire images of the precipitation formation region, precipitation front, and cluster migration; when using compatibility-verified fluorescent microspheres, the PIV module simultaneously acquires the reaction flow rate. A laser scanning confocal microscope performs three-dimensional scanning every 60 seconds to obtain the precipitation layer distribution and local aperture changes.

[0095] Step 525: Calculate the mixing ratio, mineralization intensity, sediment coverage, sediment centroid, sediment migration trajectory, local opening, equivalent hydraulic opening, equivalent permeability, and degree of blockage in real time; identify blockage when the segment pressure difference increases and the local opening decreases, and identify sediment shedding and migration when the pressure difference suddenly drops and is accompanied by an increase in outlet turbidity.

[0096] Step 6: While keeping the average flow rate, total injection volume, and total molar amount of reactants consistent, change the pulse frequency, amplitude, duty cycle, and phase difference, and change the initial fracture opening, roughness, intersection angle, or reactant concentration to analyze the effects of each parameter on mixing, mineralization, and seepage capacity.

[0097] Step 6 specifically includes: Step 61: While keeping other parameters constant, change the pulse frequency to study the matching relationship between the cycle time scale and the mixing time, reaction time, and fluid residence time.

[0098] Step 62: Change the difference between QH and QL and the duty cycle D to study low-amplitude pulses, medium-amplitude mixed-enhanced pulses, and high-amplitude pulses that may cause sediment erosion or shedding.

[0099] Step 63: Set 0°, 90°, 180° and other phase differences to analyze the interface oscillation, reaction hot spot location, sedimentation space uniformity and inlet blockage degree.

[0100] Step 64: Replace the three-dimensional transparent rock fracture model with one that has different initial opening, roughness and intersection angle, or change the concentration of sodium sulfate and barium chloride, and repeat steps 3 to 6 to study the coupling effect of geometric, chemical and pulse parameters.

[0101] Step 7: Merge the image, pressure, flow rate, and turbidity data according to a unified timestamp, calculate the local fissure opening, equivalent hydraulic opening, and equivalent permeability, and verify them by mass analysis of the outlet sample and residual sediment in the fissure.

[0102] Step 7 specifically includes: Step 71: After the experiment, preserve the samples in the waste liquid collector according to the time intervals, filter and dry the outlet particles, and analyze the Ba in the filtrate. 2+ and SO4 2- Concentration; disassemble a three-dimensional transparent rock fracture model, collect and weigh the residual precipitates inside the fractures.

[0103] Step 72: Perform a mass conservation check based on the total amount of reactants at the inlet, dissolved ions at the outlet, particulate precipitates at the outlet, and precipitates retained in the fissures; calibrate the confocal precipitate volume, two-dimensional precipitate area, and turbidity signal with the actual precipitate mass.

[0104] Step 73: Use a multi-source data fusion algorithm to establish the relationship between pulse parameters and mixing index, mineralization intensity, local aperture change, equivalent permeability, sedimentation location, migration distance and blockage degree, and compare the differences in the effects of in-phase, out-of-phase, phase difference and single-sided pulses.

[0105] Using the above method, this application can use low-amplitude pulses as diagnostic signals for fracture conditions, medium-amplitude pulses as signals for controlling mixing and precipitation positions, and adjust subsequent pulse parameters according to real-time changes in pressure, flow rate, confocal opening, and outlet turbidity, thereby providing experimental basis for underground fracture mineralization sealing, geothermal reinjection scaling control, and reactive fluid injection.

[0106] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0107] It should also be noted that, in this document, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor should they be construed as indicating or implying relative importance. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device 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 terminal device. In the absence of further restrictions, an element defined by the phrase "includes a..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes the element.

[0108] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand this application, and the content of this specification should not be construed as a limitation of this application. Furthermore, for those skilled in the art, there will be different forms of changes in the specific implementation methods and application scope based on this application. It is neither necessary nor possible to exhaustively list all implementation methods here, and obvious changes or modifications derived therefrom are still within the protection scope of this application.

Claims

1. An experimental apparatus for rock fracture mineralization, characterized in that, include: A three-dimensional transparent rock fracture model, which contains three-dimensional intersecting fracture channels with a first inlet, a second inlet, and an outlet. The three-dimensional transparent rock fracture model has multiple pressure measuring holes, which are respectively arranged in the inlet section, confluence zone, midstream zone and outlet section of the three-dimensional intersecting fracture channel; The liquid injection unit includes a first liquid storage tank, a second liquid storage tank, a first pulse injection device, and a second pulse injection device; the input terminals of the first pulse injection device and the second pulse injection device are respectively connected to the first liquid storage tank and the second liquid storage tank, and the output terminals of the first pulse injection device and the second pulse injection device are respectively connected to the first inlet and the second inlet; the first pulse injection device and the second pulse injection device are used to deliver fluid to the first inlet and the second inlet respectively in constant injection, in-phase pulse, out-of-phase pulse, phase difference pulse, and single-sided pulse modes. The hydraulic and waste liquid monitoring unit includes a first inlet pressure sensor and a second inlet pressure sensor respectively installed at the first inlet and the second inlet, an outlet pressure sensor and an outlet flow sensor installed at the outlet, multiple external sensors installed at multiple pressure measuring holes, a waste liquid collector connected to the outlet, and a turbidity monitor for detecting the turbidity of the outlet liquid. The visualization monitoring unit includes a workbench, a fluorescence imaging and a three-dimensional imaging system; the fluorescence imaging and three-dimensional imaging system is used to perform dual-color fluorescence tracer imaging, particle image velocimetry, and acquire three-dimensional images of the three-dimensional cross fracture channels in the three-dimensional transparent rock fracture model. The data acquisition and processing unit is connected to the first pulse injection device, the second pulse injection device, the first inlet pressure sensor, the second inlet pressure sensor, the outlet pressure sensor, the outlet flow sensor, multiple external sensors, the turbidity monitor, and the fluorescence imaging and three-dimensional imaging system, respectively, and is used to acquire pulse control signals, pressure signals, flow signals, turbidity signals and image signals under a unified time reference.

2. The experimental apparatus for rock fracture mineralization according to claim 1, characterized in that: The first pulse injection device and the second pulse injection device are flow pulse generators or pressure pulse generators.

3. The experimental apparatus for rock fracture mineralization according to claim 1, characterized in that: The first pulse injection device includes a first programmable injection pump, and the second pulse injection device includes a second programmable injection pump; each pulse cycle includes a high flow rate phase QH with a duration of D·T and a low flow rate phase QL with a duration of (1-D)·T, where T is the period and D is the duty cycle; the first programmable injection pump and the second programmable injection pump form in-phase pulses, out-of-phase pulses, and phase difference pulses by means of common triggering, delayed triggering, or preset different start phases.

4. The experimental apparatus for rock fracture mineralization according to claim 1, characterized in that: The three-dimensional transparent rock fracture model includes an assembled upper model and a lower model. The upper model and the lower model are respectively provided with an upper fracture replication surface and a lower fracture replication surface. The upper fracture replication surface and the lower fracture replication surface are arranged opposite to each other and sealed together to form the three-dimensional intersecting fracture channel.

5. The experimental apparatus for rock fracture mineralization according to claim 4, characterized in that: The upper model and the lower model are installed and fixed by a model clamping assembly; the model clamping assembly includes a metal clamping frame, an annular sealing groove, a sealing ring, a positioning pin and a fastening bolt; the annular sealing groove is disposed between the upper model and the lower model, and the sealing ring is embedded in the annular sealing groove and located on the periphery of the upper crack replication surface and the lower crack replication surface; The upper model and the lower model are mounted on the metal clamping frame. The upper model, the lower model, and the metal clamping frame are provided with corresponding positioning holes. The positioning pin passes through the positioning hole and is used to position and align the upper model, the lower model, and the metal clamping frame. The fastening bolt passes through the metal clamping frame, the lower model, and the upper model in sequence to connect and fix the three together.

6. The experimental apparatus for rock fracture mineralization according to claim 1, characterized in that: The materials used in the three-dimensional transparent rock fracture model include transparent epoxy resin, transparent epoxy acrylate light-cured resin, or transparent polymethyl methacrylate.

7. The experimental apparatus for rock fracture mineralization according to claim 1, characterized in that: The pressure measuring holes are connected to the external sensors via multiple short flexible tubes of the same length and inner diameter.

8. The experimental apparatus for rock fracture mineralization according to claim 1, characterized in that: The fluorescence imaging and three-dimensional imaging system includes a green laser source, a high-speed camera, a filter assembly, and a laser scanning confocal microscope; The filtering assembly includes an excitation filter disposed between the three-dimensional transparent rock fracture model and the green laser source, and an emission filter disposed at the incident end of the high-speed camera. The excitation filter and the emission filter are used to construct a green fluorescence channel, and the high-speed camera is used to acquire green fluorescence images. The laser scanning confocal microscope has a built-in red laser source, a red fluorescence channel, and a red fluorescence image acquisition window. The laser scanning confocal microscope is used to acquire red fluorescence images. The laser scanning confocal microscope is also used to scan the three-dimensional transparent rock fracture model at set time intervals and acquire three-dimensional images.

9. The experimental apparatus for rock fracture mineralization according to claim 8, characterized in that: The center wavelength of the excitation filter is 495 nm, and the center wavelength of the emission filter is 520 nm.

10. A method for experimental rock fracture mineralization, using the experimental apparatus for rock fracture mineralization as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Prepare, wash, disperse, filter, degas, and pre-treat the fluorescent tracer particles, non-reactive carrier liquid, sodium sulfate solution, and barium chloride solution at a constant temperature, and perform concentration-grayscale calibration on the fluorescent imaging and three-dimensional imaging system. Step 2: Fabricate and assemble the three-dimensional transparent rock fracture model, and complete the calibration of the image, pressure, flow, and turbidity sensors; Step 3: Inject pure water into the first inlet and the second inlet, check the device's sealing performance, establish a stable flow-pressure differential baseline, and apply a non-reactive pulse to obtain the device's background amplitude attenuation and phase delay; Step 4: Inject the first non-reactive fluid containing red fluorescent tracer particles and the second non-reactive fluid containing green fluorescent tracer particles respectively. Simultaneously acquire fluorescence images and hydraulic data under constant injection, in-phase pulse, out-of-phase pulse, phase difference pulse and single-sided pulse conditions to obtain the concentration field, mixing ratio, mixing index and velocity field of the two fluids. Step 5: Inject sodium sulfate solution and barium chloride solution respectively, and simultaneously acquire high-speed images, confocal 3D images, inlet pressure, fracture segment pressure, outlet pressure, outlet flow rate and turbidity data according to the preset pulse working conditions to obtain precipitation generation area, precipitation distribution, local aperture change, precipitation migration trajectory and blockage evolution. Step 6: While keeping the average flow rate, total injection volume and total molar amount of reactants consistent, change the pulse frequency, amplitude, duty cycle and phase difference, and change the initial fracture aperture, roughness, intersection angle or reactant concentration, and analyze the effects of each parameter on mixing, mineralization and seepage capacity. Step 7: Merge the image, pressure, flow rate, and turbidity data according to a unified timestamp, calculate the local fissure opening, equivalent hydraulic opening, and equivalent permeability, and verify them by mass analysis of the outlet sample and residual sediment in the fissure.

Images