Physical simulation device and method for fracturing and permeation enhancement and in-situ leaching injection and production of protolith

Abstract

The invention discloses a physical simulation device for protolith fracturing and permeation enhancement and in-situ leaching injection and production. The physical simulation device comprises a triaxial loading assembly, a mixing assembly, an injection assembly, an additive assembly, a flowback metering assembly and a sample, protolith stress borne by a sample is provided by pressure pillows in three directions in a pressure chamber of the triaxial loading assembly and liquid confining pressure in a liquid filling space in the pressure chamber, the mixing assembly is used for preparing in-situ immersion liquid, different additives are added into the sample through the additive assembly, and the flowback metering assembly is used for achieving multi-parameter monitoring. According to the invention, protolith boundary simulation, disturbance load application, in-situ leaching liquid continuous preparation, in-situ leaching liquid continuous injection, leaching liquid extraction and metering, multi-parameter monitoring in the reservoir transformation and mining process, reservoir fracture expansion support simulation and the like in the uranium mine reservoir transformation-mining process can be realized; through quantitative evaluation of influences of different factors in mining of in-situ leaching liquid, main factors influencing reservoir mining efficiency are determined, and reference is provided for further optimization of a uranium mine reservoir mining process.

Description

Technical Field

[0001] The invention relates to the technical field of true triaxial rock physical simulation, and in particular to a physical simulation device and method for original rock fracturing and permeability enhancement and in-situ leaching. Background Art

[0002] In recent years, in situ CO 2 -O 2 In-situ leaching of uranium has been widely promoted and applied. The in-situ leaching liquid is a corrosive liquid. After entering the ore layer, it takes a long time to react to leach the uranium. Uranium in-situ leaching is a long-term injection and mining process. The uranium in the reservoir is leached by continuously injecting in-situ leaching liquid. 4 + Oxidized to soluble U 6 +,U 6 + and HCO in the groundwater 3 - ions are leached out with the leachate after binding, and the oxygen content, HCO 3 -The ratio of ion concentration, additives and other ingredients has a great influence on the leaching efficiency of uranium ore. Before in-situ leaching, the uranium reservoir needs to be transformed into a uniform fracture network so that the ore and rock of the surrounding rock layer containing the ore are permeable to chemical solvents. The existing fracture network transformation technology is difficult to produce a homogenized fracture network in the reservoir, and most of the main fractures exist, resulting in low efficiency of in-situ leaching.

[0003] Conduct physical simulation experiments of the whole process of fracturing and permeability-increasing reservoir transformation and in-situ leaching under original rock boundary conditions in the laboratory, optimize the mining process of tight sandstone reservoirs based on the experimental results, and develop a set of tight sandstone in-situ leaching technology and equipment suitable for tight sandstone uranium reservoirs. At present, the use of blasting fracturing is the main means of reservoir transformation to produce homogenized fracture networks, including: CO 2 Micro gas explosion, CH 4 Micro gas explosion and explosive blasting, etc., but the existing blasting technology is mostly suitable for blasting scenes with free faces, and there are few studies on the physical simulation of blasting fracturing without free faces. Most simulation equipment uses rigid pad loading to simulate formation stress. During rigid loading, it is generally believed that the area 1 / 4 of the side length away from the loading surface is not affected by the boundary stress. Most areas of the sample are affected by the loading boundary under rigid loading, and the rigid loading boundary will reflect the blasting stress wave. The combination of the above factors will lead to the distortion of crack expansion during the reservoir transformation simulation process; and the existing equipment cannot realize the physical simulation of the entire process of reservoir transformation-ground mirror mining. In general, the existing physical simulation device is difficult to meet the physical simulation conditions of the entire process of in-situ leaching and mining, and has the following main deficiencies: 1. The simulation of the original rock boundary conditions is distorted, and the blasting fracturing process of the reservoir cannot be simulated. During triaxial rigid loading, the stress deformity distribution area of ​​the boundary is large, and there is stress wave reflection at the rigid boundary; 2. It is impossible to continuously prepare in-situ leaching fluid with precise ratio, which is insufficient to support the oxygen content and HCO in the in-situ leaching fluid. 3- The influence of the ratio of ion concentration, additives and other ingredients on the leaching efficiency of uranium ore is studied, and the preparation capacity is limited, which is not enough to support the physical similarity simulation experiments of continuous injection, chemical reaction and pumping backflow of leaching fluid; 3. It is impossible to simulate the extraction and metering process of leaching fluid; 4. It is not easy to apply the disturbance load in reservoir transformation; 5. The monitoring method of the destruction signal in the physical simulation process of injection and production is single, and the number of measuring points that can be arranged is small; 6. It is impossible to simulate the process of adding proppants, expanders and surfactants after reservoir transformation.

[0004] It can be seen that how to realize the physical simulation of reservoir fracturing under original rock conditions during in situ leaching is a difficult problem in optimizing uranium reservoir mining technology, especially large-scale in situ leaching physical simulation equipment and methods, which is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The purpose of the present invention is to propose a physical simulation device and method for original rock fracturing and permeability enhancement and in-situ leaching and mining, which can realize original rock boundary simulation, disturbance load application, continuous preparation of in-situ leaching liquid, continuous and accurate injection of in-situ leaching liquid, leaching liquid production and metering in the whole process of reservoir transformation-in-situ mining, as well as multi-parameter monitoring of reservoir transformation and mining process and simulation of reservoir fracture expansion support, etc., quantitatively evaluate the influence of different factors in the mining of in-situ leaching liquid, thereby clarifying the main factors affecting the efficiency of reservoir mining, and providing a reference for further optimizing the mining process of uranium ore reservoirs.

[0006] The technical solution adopted by the present invention is:

[0007] A physical simulation device for in situ rock fracturing permeability enhancement and in situ leaching, comprising a triaxial loading component, a mixing component, an injection component, an additive component, a flowback metering component and a sample; the triaxial loading component comprises a hydraulic servo system, a pressure chamber and a pressure pillow; the sample is installed in the pressure chamber, and the pressure pillows are respectively arranged below and on four sides of the sample; the in situ rock stress on the sample is provided by the pressure pillows in three directions and the liquid confining pressure in the liquid-filled space inside the pressure chamber; the internal pressure of the pressure pillow and the liquid confining pressure are provided by the hydraulic servo system; the mixing component comprises a dissolved oxygen generator, a CO 2 The booster device and mixing container group, the dissolved oxygen generator and CO 2 The outlets of the booster device are respectively connected to the inlets of the mixing container group, and the oxygen-containing solution and CO are uniformly mixed through the mixing container group. 2In order to prepare the ground immersion liquid, the outlet of the mixing container group is connected to the inlet of the injection component; the outlet of the injection component is connected to the inlet of the additive component through a branch, and the outlet of the injection component is also connected to the injection pipe of the triaxial loading component through another branch, and the injection pipe is connected to the pre-buried pipe of the sample; the inlet of the additive component is connected to the outlet of the injection component, and the outlet of the additive component is connected to the injection pipe of the triaxial loading component, and different additives are added to the sample through the additive component; the backflow metering component includes a vacuum pump, a backflow liquid outlet pipe, a solid separator, a back pressure valve, a gas-liquid separator, a gas flow meter group and a liquid flow meter group; the vacuum pump is connected to the injection pipe through a pipeline; the backflow liquid in the pressure chamber is led out through the backflow liquid outlet pipe, the solid separator, the back pressure valve, and the gas-liquid separator are sequentially arranged on the backflow liquid outlet pipe, and the gas-liquid separator is divided into a gas pipeline and a liquid pipeline, the gas flow meter group is installed on the gas pipeline, and the liquid flow meter group is installed on the liquid pipeline.

[0008] In the above scheme, the hydraulic servo system includes an X-direction oil circuit, a Y-direction oil circuit, a Z-direction oil circuit and a confining pressure oil circuit, the X-direction oil circuit is connected to the pressure pillow below the sample, the Y-direction oil circuit is connected to the pressure pillows on the left and right sides of the sample, the Z-direction oil circuit is connected to the pressure pillows on the front and back sides of the sample, and the confining pressure oil circuit is connected to the liquid-filled space inside the pressure chamber; when loading, the internal pressure value of the pressure pillow is greater than the liquid confining pressure value.

[0009] In the above scheme, the pressure pillow includes a pressure pillow shell, an elastic lining and granular material. The elastic lining is arranged inside the pressure pillow shell, and the elastic lining is filled with granular material.

[0010] In the above scheme, the backflow metering assembly also includes a liquid sampler and a gas sampler. The liquid sampler is arranged on the branch between the solid separator and the back pressure valve, and the gas sampler is arranged on the pipeline after the gas flow meter group.

[0011] In the above scheme, the dissolved oxygen generating device comprises an oxygen gas source, an oxygen solution stirring container and a water source, the outlets of the oxygen gas source and the water source are respectively connected to the inlet of the oxygen solution stirring container, and the outlet of the oxygen solution stirring container is connected to the inlet of the mixing container group; the CO 2 The booster device includes a CO 2 Gas source, CO 2 Booster pump, CO 2 Storage tanks and CO 2 Metering pump, CO 2 The outlet of the metering pump is connected to the inlet of the mixing container group.

[0012] In the above scheme, the outlet pipeline of the oxygen gas source is provided with an oxygen pressure regulating valve, an oxygen pressure gauge and an oxygen stop valve; the oxygen solution stirring container is provided with an oxygen content sensor and a liquid level meter (212), and the outlet pipeline of the oxygen solution stirring container is provided with an oxygen solution metering pump and a stop valve (216).

[0013] In the above scheme, the CO 2 The inlet pipe of the tank is equipped with a CO 2 Pressure gauge, CO 2 The outlet pipe of the storage tank is equipped with a CO 2 Safety valve and stop valve (253), CO 2 The outer shell of the storage tank is provided with a heat preservation and heating jacket; the CO 2 The outlet pipe of the metering pump is equipped with a CO 2 Pressure regulating valve, CO 2 Pressure gauge and stop valve (263), CO 2 The outer shell of the metering pump is provided with a heat-insulating heating jacket.

[0014] In the above scheme, a liquid level meter (272) and a heat preservation and heating jacket are arranged outside the mixing container group, and a stop valve (273) is arranged on the outlet pipeline of the mixing container group.

[0015] In the above scheme, the injection assembly adopts a double-cylinder constant speed and constant pressure injection pump, and the double-cylinder constant speed and constant pressure injection pump includes a first single pump 321 and a second single pump 322 arranged in parallel. The inlet pipeline of the first single pump 321 is provided with a stop valve (312), and the outlet pipeline is provided with a stop valve (313). The inlet pipeline of the second single pump 322 is provided with a stop valve (314), and the outlet pipeline is provided with a stop valve (315). The two single pumps can independently perform liquid suction and liquid discharge actions.

[0016] In the above scheme, the additive assembly includes a high-pressure storage tank, a screw pump and a screw pump motor. The lower funnel outlet of the high-pressure storage tank is connected to the outlet of the injection assembly. The additive in the high-pressure storage tank falls to the outlet under its own weight and mixes with the immersion liquid. The screw pump motor rotates the screw pump to pump the mixed immersion liquid into the cracks inside the sample.

[0017] In the above scheme, the triaxial loading assembly also includes an end pad block arranged around the sample, and space for arranging various monitoring probes is reserved in the end pad block to meet the arrangement requirements of acoustic wave probes, strain gauges, optical fibers and electrodes, and support the arrangement of array-type acoustic wave probes; a water distribution trough and a pad diversion hole are also provided in the end pad block to divert the ground immersion liquid flowing through the embedded pipes and seam networks in the sample out of the pressure chamber.

[0018] In the above scheme, the three-axis loading assembly also includes an end cover assembly, and the end cover assembly includes an upper end cover, a lower end cover, a shear ring gasket and a shear ring. The upper end cover is installed at the upper end of the pressure chamber, and the upper end cover is provided with an upper end cover sealing ring along the annular direction; the lower end cover is installed at the lower end of the pressure chamber, and the lower end cover is provided with a lower end cover sealing ring along the annular direction; the shear ring is installed on the inner wall of the pressure chamber and is located above the upper end cover, and the shear ring gasket is installed between the upper end cover and the shear ring.

[0019] In the above scheme, the three-axis loading assembly also includes a supporting pad assembly, which includes an upper pad, a lower tray, an annular pad and a lower pad. The upper pad is installed between the vertical end pad and the upper end cover, the lower tray is installed at the lower end of the pressure pillow below the sample, the lower pad is installed between the lower tray and the lower end cover, and the annular pad is installed between the outer periphery of the lower pad and the inner wall of the pressure chamber.

[0020] In the above scheme, holes are respectively opened in the centers of the upper end cover, the upper pad, and the vertical end pad for applying engineering disturbance loads, and a fixing hole for the disturbance load device is provided at the upper end of the pressure chamber; plane seals are respectively provided between the upper end cover and the upper pad, and between the upper pad and the vertical end pad to prevent the confining pressure liquid from seeping out from the gaps between the pads.

[0021] In the above scheme, the three-axis loading assembly also includes a wedge pad assembly arranged between the pressure pillow and the inner wall of the pressure chamber, the wedge pad assembly includes a circular arc wedge pad and a square wedge pad, the circular arc wedge pad is installed on the inner wall of the pressure chamber, and the square wedge pad is installed between the circular arc wedge pad and the pressure pillow.

[0022] In the above scheme, the original rock fracturing permeability enhancement and in-situ leaching physical simulation device also includes a multi-parameter acquisition component, which includes a variety of monitoring probes and acquisition instruments and signal cables connecting the monitoring probes and the acquisition instruments; the various monitoring probes are installed in the end pad, and the types of the various monitoring probes include acoustic emission probes, ultrasonic probes, strain gauges, optical fibers, and electrode acceleration sensors. The types of the acquisition instruments include acoustic emission acquisition cards, acoustic wave acquisition cards, strain gauges, optical fiber instruments, resistivity acquisition instruments, and acceleration acquisition instruments.

[0023] Correspondingly, the present invention also proposes a physical simulation method for in situ leaching of original rock, which uses the above-mentioned in situ rock fracturing, permeability enhancement and in situ leaching physical simulation device, and comprises the following steps:

[0024] Use a vacuum pump to evacuate the sample from the injection hole and the embedded pipe;

[0025] Start the mixing component, prepare the ground leaching liquid required for the simulation experiment in the mixing container group, and fill the ground leaching liquid with the double-cylinder constant speed and constant pressure pump in the injection component, then close all the stop valves, and add additives to the additive component;

[0026] In-situ rock stress application: first apply vertical stress to 2MPa-5MPa, fix the sample, and then apply 2MPa-5MPa horizontal pressure. After the pressure stabilizes, apply confining pressure, and then simultaneously increase the three-dimensional stress and confining pressure to the target pressure; during the loading process, keep the internal pressure of the pressure pillow greater than the confining pressure; heat the pressure chamber as a whole by wrapping a heat-insulating heating jacket outside the pressure chamber; after the pressure is stabilized, observe whether there is confining pressure liquid flowing out of the injection hole on the end pad and the embedded pipe in the sample. If there is liquid flowing out, terminate the experiment and install the next sample until there is no liquid flowing out; monitor and record the state of the sample, including the acoustic wave velocity of the sample, the initial strain of each measuring point, and the resistance value, as the subsequent monitoring baseline;

[0027] Physical simulation of reservoir transformation: fix the disturbance load simulation device on the pressure chamber, embed the shock wave generator at the bottom of the embedded pipe hole, release the cylindrical shock wave after excitation, simulate the reservoir transformation, i.e. the homogenization fracture network construction process, after the disturbance load is applied, remove the disturbance load simulation device; open the stop valves related to the injection component and the additive component, set the injection flow rate of the in-situ leaching liquid, pump the additive into the fracture network, use the liquid collecting tank to collect the waste liquid discharged from the return liquid pipeline, and close all the stop valves after the above operations are completed;

[0028] Physical simulation of in-situ leaching process: start the mixing component, injection component, backflow metering component and control component, set the in-situ leaching solution concentration, injection pressure and production pressure according to the target values, inject the in-situ leaching solution into the sample, produce the uranium ore in the sample through chemical reaction, use the gas flow meter group and liquid flow meter group in the backflow metering component to record the gas flow and liquid flow in the produced material respectively, and use the gas sampler and liquid sampler to collect the produced gas and liquid for inspection and analysis; start the back pressure valve, set the back pressure valve pressure, start the injection component, set the injection flow, and continuously inject the in-situ leaching solution until The pressure value fluctuation of the injection port pressure gauge is less than 1MPa / min, and the value of the injection port pressure gauge is recorded; the Darcy formula is used to calculate the equivalent permeability of the reservoir at this time; during the experiment, the sound, light, electricity, temperature, pressure, and flow data observed during the simulation process are recorded through a multi-parameter acquisition component; by analyzing the sound, light, electricity, temperature, pressure, flow and other data during the reservoir transformation and exploitation process, and inverting the multi-parameter monitoring signal to study the fracture network evolution process before reservoir transformation and during exploitation, the main factors affecting the reservoir exploitation efficiency can be further clarified, and a quantitative evaluation of different factors can be made.

[0029] The beneficial effects produced by the present invention are:

[0030] The present invention can realize the original rock boundary simulation, disturbance load application, continuous preparation of leaching fluid, continuous and accurate injection of leaching fluid, leaching fluid extraction and metering, as well as multi-parameter monitoring of reservoir transformation and mining process and reservoir fracture expansion support simulation in the whole process of reservoir transformation and mining. Among them:

[0031] 1. The present invention adopts a pressure pillow to apply the original rock stress of the sample, fills the granular energy-absorbing material in the elastic lining of the pressure pillow, absorbs the stress shock wave generated during the blasting process, suppresses the rebound of the boundary stress wave, and simultaneously applies liquid confining pressure to improve the stress deformity of the boundary during rigid loading, thereby meeting the loading requirements of the original rock stress of the reservoir.

[0032] 2. The present invention applies disturbance load by fixing a disturbance load simulation device on the top of the pressure chamber, and pre-buries a shock wave generating device at the bottom of the hole of the pre-buried pipe, and releases cylindrical shock waves after excitation to simulate reservoir transformation, that is, the homogenization fracture network construction process.

[0033] 3. The present invention prepares the ground leaching solution by mixing components, and controls the oxygen solution and CO 2 The temperature and pressure conditions are then used to pump oxygen solution and CO 2 The metering pumps are used to add oxygen solution and CO with a certain concentration into the mixing container group. 2 Mix and prepare in-situ leaching liquid, and set up more than two mixing container groups that can be switched for use to meet the needs of continuous preparation of in-situ leaching liquid during the physical simulation process of in-situ leaching mining.

[0034] 4. The present invention uses a dual-cylinder constant-speed constant-pressure injection pump of an injection component to output in-situ leaching fluid at a set flow rate and pressure. During this period, an additive component can be used to quantitatively add proppant, swelling agent and surfactant to the in-situ leaching fluid and inject them into the transformed reservoir fracture network to meet the research needs on the effects of different additives on reservoir transformation.

[0035] 5. Different types of monitoring probes can be arranged in the end pads to meet the needs of multi-parameter collection during in-situ leaching.

[0036] 6. Use injection components and flowback metering components to measure the reservoir equivalent permeability and recovery rate; quantitatively evaluate the reservoir transformation and production effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1It is a schematic diagram of the overall structure of the physical simulation device for in situ rock fracturing, permeability enhancement and in situ leaching and mining according to the present invention;

[0039] Figure 2 yes Figure 1 A schematic diagram of the structure of a triaxial loading assembly of a physical simulation device for in situ rock fracturing, permeability enhancement and in situ leaching;

[0040] Figure 3 yes Figure 2 A schematic structural diagram of a pressure pillow of a triaxial loading assembly shown;

[0041] Figure 4 yes Figure 2 A schematic diagram of the structure of the end pad of the triaxial loading assembly shown;

[0042] Figure 5 yes Figure 2 A schematic structural diagram of the lower end cover of the triaxial loading assembly is shown.

[0043] In the figure: 11-hydraulic servo system, 111-X direction oil circuit, 112-Y direction oil circuit, 113-Z direction oil circuit, 114-confining pressure oil circuit, 12-pressure chamber, 121-fixing hole of disturbance load device, 122-lifting ear, 123-pressure chamber base, 124-liquid filling space inside the pressure chamber, 131-upper end cover, 1311-upper end cover sealing ring, 1312-upper end cover exhaust hole stop valve, 1313-upper end cover exhaust hole, 132-lower end cover, 1321-lower end cover sealing ring, 1322-monitoring signal line through-cabin joint, 1323-pressurized pipe through-cabin joint, 1324-cross-shaped lower pad placement area, 1325, 1327-through-cabin hole, 1326-circular lower pad placement area, 133-shear ring pad, 134-shear ring, 141-circular wedge pad, 142-square wedge pad, 151-horizontal end pad, 1511-monitoring probe arrangement blind hole, 1512-monitoring probe arrangement through hole, 1513-water distribution trough, 1514-wire trough, 1515-pad diversion hole, 152-vertical end pad, 161-upper pad, 1611-plane seal, 162-lower tray, 163-ring pad, 164-lower pad, 17-pressure pillow, 171-pressure pillow shell, 172-elastic lining, 173-granular material, 174-pressure pillow high-pressure pipe,

[0044] 21-oxygen solution stirring container, 211-oxygen content sensor, 212-liquid level meter, 214-motor, 215-oxygen solution metering pump, 217-oxygen circulation pump, 22-oxygen gas source, 221-oxygen pressure regulating valve, 222-oxygen pressure gauge, 223-oxygen stop valve, 23-CO 2 Gas source, 24-CO 2 Booster Pump, 25-CO 2Storage tank, 251-CO 2 Pressure Gauge, 252-CO 2 Safety valve, 26-CO 2 Metering Pump, 261-CO 2 Pressure Regulator, 262-CO 2 Pressure gauge; 27-mixing container group, 271-frequency conversion motor, 272-liquid level meter, 28-water source,

[0045] 318-safety valve, 319-injection port pressure gauge, 320-injection pipe, 321-first single pump, 322-second single pump,

[0046] 41- High-pressure storage tank, 42- Screw pump, 43- Screw pump motor,

[0047] 51- vacuum pump, 511- high pressure stop valve, 512- dryer, 52- solid separator, 521- return liquid outlet pipe, 522- outlet pressure gauge, 53- back pressure valve, 531- back pressure valve buffer container, 532- back pressure pressure gauge, 533- back pressure tracking pump, 54- gas-liquid separator, 541- dryer, 542- gas flow meter group, 543- liquid flow meter group, 544- return liquid storage tank, 55- gas sampler, 56- liquid sampler, 57- liquid collecting tank,

[0048] 6-multi-parameter acquisition component, 61-monitoring probe, 62-in-cabin signal line, 63-out-cabin signal line,

[0049] 7-control component, 71-control signal line,

[0050] 8-sample, 81-seam mesh, 82-prefabricated groove, 83-buried pipe,

[0051] 213, 216, 281, 253, 263, 273, 312, 313, 314, 315, 316, 317, 44, 45, 46, 551, 552, 561, 562, 571, 58 - stop valve. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] It should be noted that the illustrations provided in the embodiments of the present invention are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout type may also be more complicated.

[0054] In the present invention, it is also necessary to explain that, if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first" and "second" appear, they are only used for description and distinction purposes, and cannot be understood as indicating or implying relative importance.

[0055] Embodiment 1: Device embodiment

[0056] like Figure 1 As shown, a physical simulation device for in situ rock fracturing, permeability enhancement and in situ leaching provided by an embodiment of the present invention includes a triaxial loading component, a mixing component, an injection component, an additive component, a flowback metering component, a multi-parameter acquisition component, a control component and a sample. The triaxial loading component includes a hydraulic servo system 11, a pressure chamber 12 and a pressure pillow 17. The sample 8 is installed in the pressure chamber 12. Pressure pillows 17 are respectively provided below and on the four sides of the sample 8. The in situ rock stress on the sample 8 is provided by the pressure pillows 17 in three directions and the liquid confining pressure in the liquid-filled space 124 inside the pressure chamber. The internal pressure of the pressure pillow 17 and the liquid confining pressure are provided by the hydraulic servo system 11. The mixing component is used to prepare in situ leaching solution, including a dissolved oxygen generator, a CO 2 Booster and mixing container group 27, dissolved oxygen generator and CO 2The outlets of the booster device are respectively connected to the inlets of the mixing container group 27, and the outlets of the mixing container group 27 are connected to the inlet of the injection assembly. The outlet of the injection assembly is connected to the inlet of the additive assembly through a branch, and the outlet of the injection assembly is also connected to the injection pipe of the triaxial loading assembly through another branch, and the injection pipe is connected to the embedded pipe 83 of the sample 8. The inlet of the additive assembly is connected to the outlet of the injection assembly, and the outlet of the additive assembly is connected to the injection pipe 320 of the triaxial loading assembly, and different additives are added to the sample 8 through the additive assembly. The backflow metering assembly includes a vacuum pump 51, a backflow liquid outlet pipe 521, a solid separator 52, a back pressure valve 53, a gas-liquid separator 54, a gas flow meter group 542 and a liquid flow meter group 543; the vacuum pump 51 is connected to the injection pipe 320 through a pipeline; the backflow liquid in the pressure chamber 12 is led out through the backflow liquid outlet pipe 521, the solid separator 52, the back pressure valve 53, and the gas-liquid separator 54 are sequentially arranged on the backflow liquid outlet pipe 521, and the gas-liquid separator 54 is divided into a gas pipeline and a liquid pipeline, the gas flow meter group 542 is installed on the gas pipeline, and the liquid flow meter group 543 is installed on the liquid pipeline. Sample 8 is a square sample, and a prefabricated groove 82 and a pre-buried pipe 83 are arranged in the sample 8. The function of the prefabricated groove 82 is to orient the crack initiation and expansion. During the simulation transformation, a seam network 81 is generated in the sample 8, and the expansion of the seam network 81 will connect the pre-buried pipe 83 with the surface of the sample 8.

[0057] After the sample 8 is installed in the triaxial loading assembly, a flat pressure pillow 17 is used to apply the three-dimensional original rock boundary stress of the sample 8, and a liquid confining pressure is applied in the pressure chamber 12 to improve the stress uniformity of the sample 8; an external engineering disturbance simulation device is used to apply disturbance to generate a fracture network 81 in the sample 8; a mixing assembly is used to continuously prepare the required in-situ immersion liquid for simulation, the dissolved oxygen content in the oxygen-containing solution is controlled by controlling the temperature and pressure in the dissolved oxygen generating device, and the oxygen-containing water is injected into the mixing container group 27 using the oxygen solution metering pump 215; a CO 2 Booster components produce high-pressure CO 2 , through CO 2 The metering pump 26 accurately adds CO to the mixing container group 27. 2 , the oxygen-containing solution and CO are uniformly mixed by the mixing container group 27 2; Then use the injection assembly to output the in-situ leaching liquid at the set flow rate and pressure, during which the additive assembly can be used to quantitatively add proppant, expansion agent and other components to the in-situ leaching liquid; finally, the outlet pressure is set by the back pressure valve 53 of the backflow metering assembly, and a gas-liquid separator 54 is set after the back pressure valve 53 to separate the gas and liquid, and the gas flow meter group 542, the liquid flow meter group 543 and the sampler and chromatograph are used to measure the flow rate, concentration and composition of the backflow liquid, so as to calculate the permeability coefficient of the reservoir through Darcy's law and evaluate the permeability of the fracture network 81. In the above process, the mixing speed, injection flow rate, injection pressure, etc. of the in-situ leaching liquid are controlled by the control assembly, and the multi-parameter acquisition assembly is used to monitor the reservoir transformation-in-situ leaching mining physical simulation process through different measuring points, and the multi-parameter inversion of the fracture network 81 morphology is performed; finally, quantitative research is achieved in the in-situ leaching injection and mining process.

[0058] like Figure 2 As shown, the hydraulic servo system 11 includes an X-direction oil circuit 111, a Y-direction oil circuit 112, a Z-direction oil circuit 113 and a confining pressure oil circuit 114. The X-direction oil circuit 111 is connected to the pressure pillow 17 below the sample 8, the Y-direction oil circuit 112 is connected to the pressure pillows 17 on the left and right sides of the sample 8, the Z-direction oil circuit 113 is connected to the pressure pillows 17 on the front and rear sides of the sample 8, and the confining pressure oil circuit 114 is connected to the liquid-filled space inside the pressure chamber 12. The triaxial pressure on the sample 8 is provided by the pressure pillows 17 in three directions and the liquid confining pressure. The internal pressure of the pressure pillow 17 and the liquid confining pressure are provided by the corresponding oil circuit and the hydraulic servo system 11. Each hydraulic branch is provided with a servo valve, a safety valve and a filter. A booster is provided when necessary. The injection pressure is precisely controlled by a servo controller to prevent the pressure pillow 17 in a certain direction from deforming excessively and causing the sample 8 to deviate from the center position. In addition, in order to prevent the oil temperature from being too high during continuous operation, a water cooler with cooling performance matching the heat generation is provided. When loaded, the internal pressure value of the pressure pillow 17 is greater than the liquid confining pressure value, and the force uniformity of the sample 8 is improved by applying a certain confining pressure.

[0059] Further optimization, the three-axis loading assembly also includes end pads arranged around the sample 8. By grooving, drilling and prefabricating interfaces in the end pads, monitoring probes are arranged on the surface of the sample 8, and the signals of the monitoring probes are transmitted using the in-cabin signal line, the signal line through the cabin joint and the out-cabin signal line.

[0060] The material of the end pad and the pressure pillow 17 is a high-density alloy, which can well conduct the stress shock wave transmitted from the sample 8. Figure 3As shown, the pressure pillow 17 includes a pressure pillow shell 171, an elastic lining 172 and a granular material 173. The elastic lining 172 is arranged inside the pressure pillow shell 171, and the granular material 173 is filled in the elastic lining 172, which can effectively absorb the stress shock wave transmitted by the end pad and reduce the interface rebound of the stress shock wave on the loading boundary. The energy absorption performance of the granular material 173 can be adjusted by setting the particle size gradation of the granular material 173.

[0061] Further optimization, the end pad includes a horizontal end pad 151 and a vertical end pad 152. The end pad is reserved with space for arranging various monitoring probes, meeting the arrangement requirements of acoustic wave probes, strain gauges, optical fibers and electrodes, and supporting the arrangement of array acoustic wave probes; the end pad is also provided with a water distribution trough and a pad diversion hole, which is used to divert the ground leaching liquid flowing through the embedded pipe 83 and the seam network 81 in the sample 8 out of the pressure chamber 12. Take the horizontal end pad 151 as an example, see Figure 5 A monitoring probe arrangement blind hole 1511, a monitoring probe arrangement through hole 1512, a wire trough 1514, a water distribution trough 1513 and a pad block diversion hole 1515 are provided in the horizontal end pad 151. Different monitoring probes are arranged in the monitoring probe arrangement blind hole 1511, the monitoring probe arrangement through hole 1512 and the wire trough 1514. The ground leaching liquid flowing through the embedded pipe 83 and the seam network 81 in the sample 88 is diverted out of the pressure chamber 12 through the water distribution trough 1513 and the pad block diversion hole 1515.

[0062] Further optimization, the three-axis loading assembly also includes an end cover assembly, which includes an upper end cover 131, a lower end cover 132, a shear ring pad 133 and a shear ring 134. The upper end cover 131 is installed at the upper end of the pressure chamber 12, and the upper end cover 131 is provided with two upper end cover sealing rings 1311 along the circumferential direction. The lower end cover 132 is installed at the lower end of the pressure chamber 12, and the lower end cover 132 is provided with two lower end cover sealing rings 1321 along the circumferential direction. The shear ring 134 is installed on the inner wall of the pressure chamber 12 and is located above the upper end cover 131. The shear ring 134 is annular and is cut into multiple sections when used for easy installation and operation; the shear ring pad 133 is installed between the upper end cover 131 and the shear ring 134.

[0063] Further optimized, the three-axis loading assembly also includes a supporting pad assembly, which includes an upper pad 161, a lower tray 162, an annular pad 163 and a lower pad 164, the upper pad 161 is installed between the vertical end pad 152 and the upper end cover 131, the lower tray 162 is installed at the lower end of the pressure pillow 17 below the sample 8, the lower pad 164 is installed between the lower tray 162 and the lower end cover 132, and the annular pad 163 is installed between the outer periphery of the lower pad 164 and the inner wall of the pressure chamber 12.

[0064] like Figure 4As shown, in this embodiment, two opening solutions of the lower end cover 132 corresponding to the shapes of the lower pad 164 are exemplified. Figure 4 -a corresponds to the opening scheme of the lower end cover 132 when the lower pad 164 is cross-shaped, the cross-shaped lower pad placement area 1324 is used to place the lower pad 164, and the through-tank hole 1325 is used to arrange various through-tank joints. Figure 4 -b corresponds to the opening scheme of the lower end cover 132 when the lower pad 164 is circular. The circular lower pad placement area 1326 is used to place the lower pad 164, and the through-cabin hole 1327 is used to arrange various through-cabin connectors. The types of through-cabin connectors include but are not limited to the monitoring signal line through-cabin connector 1322 and the pressurized pipe through-cabin connector 1323. The material and seal of the through-cabin connector are selected according to different pressures and temperatures.

[0065] Further optimization, the center of the upper end cover 131, the upper pad 161, and the vertical end pad 152 are respectively opened for applying engineering disturbance loads such as drilling excavation, blasting impact, and hydraulic fracturing. The upper end of the pressure chamber 12 is provided with a disturbance load device fixing hole 121 for installing an engineering disturbance simulation device. Planar seals 1611 are respectively provided between the upper end cover 131 and the upper pad 161 and between the upper pad 161 and the vertical end pad 152 to prevent the confining pressure fluid from leaking out from the gaps between the pads.

[0066] Further optimized, the three-axis loading assembly also includes a wedge pad assembly arranged between the pressure pillow 17 and the inner wall of the pressure chamber 12, the wedge pad assembly includes a circular arc wedge pad 141 and a square wedge pad 142, the circular arc wedge pad 141 is installed on the inner wall of the pressure chamber 12, and the square wedge pad 142 is installed between the circular arc wedge pad 141 and the pressure pillow 17.

[0067] For further optimization, the wall thickness of the pressure chamber 12 is designed and verified in accordance with the current standard specifications, and the material of the pressure chamber 12 is determined in combination with the use conditions and standard specifications. The outer wall of the pressure chamber 12 is provided with symmetrical lifting ears 122 for lifting the pressure chamber 12, and the lower end of the pressure chamber 12 is provided with a pressure chamber base 123. When installing the sample 8, the sample 8 and the end pads are placed on the lower tray 162, and then hoisted into the pressure chamber 12. The wedge pads are used to adjust the horizontal position of the sample 8 before loading, and the vertical height of the sample 8 is adjusted by the vertical pressure pillow 17.

[0068] Continue to see Figure 1, a mixing component, wherein the dissolved oxygen generating device comprises an oxygen gas source 22, an oxygen solution stirring container 21 and a water source 28, wherein the oxygen gas source 22 and the water source 28 are respectively connected to the inlet of the oxygen solution stirring container 21, and the outlet of the oxygen solution stirring container 21 is connected to the inlet of the mixing container group 27. An oxygen pressure regulating valve 221, an oxygen pressure gauge 222 and an oxygen stop valve 223 are arranged on the outlet pipeline of the oxygen gas source 22; an oxygen content sensor 211 and a liquid level gauge 212 are arranged on the oxygen solution stirring container 21, an oxygen solution metering pump 215 and a stop valve 216 are arranged on the outlet pipeline of the oxygen solution stirring container 21, and a heat preservation heating jacket is arranged on the outer wall of the oxygen solution stirring container 21 to control its temperature. A motor 214 is arranged above the oxygen solution stirring container 21, and the oxygen solution stirring container 21 is also provided with an oxygen circulation pump 217, through which oxygen circulates inside the oxygen solution stirring container 21 to accelerate the mixing process, and when the oxygen content reaches the target value, the stirring and oxygenation are stopped. A stop valve 281 is provided on the outlet pipeline of the water source 28 .

[0069] CO 2 The booster device includes a CO 2 Gas source 23, CO 2 Booster pump 24, CO 2 Tank 25 and CO 2 Metering pump 26, CO 2 The outlet of the metering pump 26 is connected to the inlet of the mixing container group 27. 2 The inlet pipeline of the storage tank 25 is provided with a CO 2 Pressure gauge 251, CO 2 The outlet pipe of storage tank 25 is provided with a CO 2 Safety valve 252 and stop valve 253, CO 2 The outer shell of the storage tank 25 is provided with a heat preservation and heating jacket; 2 The outlet pipe of the metering pump 26 is provided with a CO 2 Pressure regulating valve 261, CO 2 Pressure gauge 262 and stop valve 263, CO 2 The outer shell of the metering pump 26 is provided with a heat-insulating heating jacket. 2 The function of the pressure regulating valve 261 is to accurately measure CO 2 The injection volume provides a stable outlet pressure.

[0070] The mixing container group 27 is provided with a variable frequency motor 271 , a liquid level meter 272 and a heat preservation and heating jacket are provided outside the mixing container group 27 , and a stop valve 273 is provided on the outlet pipeline of the mixing container group 27 .

[0071] Further optimization, at least two sets of oxygen solution stirring containers 21 are configured, and the volume of oxygen solution stirring containers 21 is set according to the required flow rate, which can be cyclically switched to meet the needs of continuous preparation of ground leaching liquid. The mixing container group 27 is configured with at least two sets of mixing containers, which are pressure-resistant components and can be connected to high-pressure gas to drive the solution in the component to the injection assembly.

[0072] When preparing the oxygen solution, open the water source 28 and the stop valve 281 to inject water into the oxygen solution stirring container 21 to a predetermined liquid level, then close the water source 28 and the stop valve 281, then open the oxygen gas source 22, open the stop valve 223, close the stop valve 213, adjust the low pressure of the oxygen pressure reducing valve 221 to a set value, use the oxygen gas source 22 and the oxygen pressure reducing valve 221 to inject oxygen into the oxygen solution stirring container 21, monitor the oxygen content in the solution through the oxygen content sensor 211, and further accurately control the oxygen content in the oxygen solution by controlling the temperature and pressure environment of the oxygen solution stirring container 21; when the oxygen content reaches the target value C, close the oxygen pressure reducing valve 221, close the stop valve 223, open the stop valves 213 and 216, use the oxygen solution metering pump 215 to pump the oxygen-containing solution into the mixing container group 2727, and record the volume V of the oxygen solution through the liquid level gauge 272 on the mixing container group 27.

[0073] Preparation of supercritical CO 2 When the stop valve 253 is closed, the CO 2 Gas source 23, start CO 2 Booster pump 24 makes CO 2 The booster pump 24 converts CO 2 CO in tank 25 2 Pressurize to target pressure P through CO 2 The heat preservation and heating jacket outside the storage tank 25 transmits CO 2 When heated to a pressure above the supercritical temperature, CO 2 Tank 25 is filled with supercritical CO 2 After that, turn off CO 2 Booster pump 24. Add CO to the mixing container group 27 2 When the stop valves 216 and 273 are closed, the stop valves 253 and 263 are opened, and the CO 2 Pressure reducing valve 261, set the outlet pressure to P, start CO 2 The metering pump 26 delivers a preset amount of CO 2 Inject it into the mixing container group 27, close the stop valve 263, turn on the variable frequency motor 271 to start stirring the mixed liquid, and close the inlet stop valve 263 after mixing evenly. If necessary, switch to another mixing container group 27 to repeat the filling of oxygen solution and CO 2 The operation is continued until a predetermined amount of ground leaching liquid is prepared.

[0074] Continue to see Figure 1 The injection component adopts a double-cylinder constant speed and constant pressure injection pump, which includes a first single pump 321 and a second single pump 322 arranged in parallel. The inlet pipeline of the first single pump 321 is provided with a stop valve 312, and the outlet pipeline is provided with a stop valve 313. The inlet pipeline of the second single pump 322 is provided with a stop valve 314, and the outlet pipeline is provided with a stop valve 315. The two single pumps can independently perform liquid suction and discharge actions. When the ground immersion liquid is continuously injected, the stop valves 312, 315, 273, and 316 are opened, the stop valves 313 and 314 are closed, the second single pump 322 discharges the liquid, and the first single pump 321 absorbs the liquid, and the liquid absorption speed is 1.5 times the liquid discharge speed. After the liquid is fully absorbed, the stop valve 312 is closed. When the ground immersion liquid in the second single pump 322 is completely discharged, the stop valves 313 and 314 are opened, the stop valves 312 and 315 are closed, and the first single pump 321 is switched to discharge the liquid, and the second single pump 322 absorbs the liquid. This cyclic switching is carried out to realize the continuous injection of the ground immersion liquid. Therefore, the present invention can use two constant speed and constant pressure injection pumps to cyclically absorb the ground immersion liquid in the mixing container group 27, and output the ground immersion liquid according to the predetermined flow rate and pressure.

[0075] Continue to see Figure 1 The additive assembly includes a high-pressure storage tank 41, a screw pump 42 and a screw pump motor 43. The lower part of the high-pressure storage tank 41 is a funnel structure. The outlet of the injection assembly is connected to the outlet of the lower funnel of the high-pressure storage tank 41. The additive in the high-pressure storage tank 41 falls to the outlet under its own weight and mixes with the ground leaching liquid. The screw pump motor 43 rotates the screw pump 42 to pump the mixed ground leaching liquid into the cracks inside the sample 8. The types of additives include proppants, expanders and activators.

[0076] Continue to see Figure 1 The backflow metering assembly also includes a liquid sampler 56 and a gas sampler 55. The liquid sampler 56 is arranged on the branch between the solid separator 52 and the back pressure valve 53, and the gas sampler 55 is arranged on the pipeline after the gas flow meter group 542. After the backflow liquid flows out from the backflow liquid outlet pipe 521, the solid particles are first separated by the solid separator 52. The backflow liquid is collected by the liquid sampler 56 and sent for inspection and measurement of oxygen and HCO 3 - content; the outlet pressure of the return liquid is controlled by setting a back pressure valve 53, and the pressure of the return liquid drops to atmospheric pressure after passing through the back pressure valve 53. After the return liquid passes through the gas-liquid separator 54, the gas flow meter group 542 and the liquid flow meter group 543 are used to measure the flow of gas and liquid in the return liquid. A gas sampler 55 is used to collect the gas in the return liquid, and the proportion of each component in the mixed gas is measured by a chromatograph analysis method.

[0077] Further optimization: the gas flow meter is composed of 3-5 flow meters with different ranges connected in parallel, and the gas flow meters with different ranges are automatically switched according to the flow rate when in use; the liquid flow meter is composed of 2-3 flow meters with different ranges connected in parallel, and the liquid flow meters with different ranges are automatically switched according to the flow rate when in use.

[0078] For further optimization, a branch is provided on the pipeline after the gas flow meter group 542 to connect to the atmosphere, and a stop valve 58 is installed on the branch.

[0079] For further optimization, the number of gas samplers 55 is no less than 3, which are connected to the pipeline behind the stop valve 552 through a quick connector. When in use, the stop valve 58 is closed, and the stop valves 551 and 552 are opened. After the sampling is completed, the stop valve 551 is closed, and the stop valve 58 is opened (connected to the atmosphere).

[0080] Further optimization, a dryer 512 is provided before the vacuum pump 5151 to prevent oil and water pollution in the vacuum pump 51. A high-pressure stop valve 511 is provided before the dryer 512.

[0081] Further optimized, the back pressure valve 53 includes a back pressure valve buffer container 531, a pressure sensor 532 and a back pressure tracking pump 533. The back pressure is set by setting the pressure of the back pressure tracking pump 533. The function of the back pressure buffer container 531 is to prevent the outlet impact pressure from causing the back pressure valve 53 tracking pump pressure overload.

[0082] The multi-parameter acquisition component includes a variety of monitoring probes and acquisition instruments and signal cables connecting the monitoring probes and the acquisition instruments. The signal cable is composed of an in-cabin signal line 62, a monitoring signal line cabin joint 1322 and an out-cabin signal line 63, which transmits the monitoring signal to the multi-parameter acquisition component. The monitoring signal line cabin joint 1322 passes through the lower end cover 132 of the triaxial loading component. The types of various monitoring probes include acoustic emission probes, ultrasonic probes, strain gauges, optical fibers, electrodes, and acceleration sensors. The types of acquisition instruments include acoustic emission acquisition cards, acoustic wave acquisition cards, strain gauges, optical fiber instruments, resistivity acquisition instruments, and acceleration acquisition instruments. Various signal acquisition instruments use a method based on a time synchronization protocol to synchronize the time of different acquisition instruments. Various signal acquisition instruments use the same data transmission communication protocol to store the collected data in a file in the same dynamic data format. While storing the data, the data stored in the database can be read to perform multi-parameter data analysis on the experimental process.

[0083] The control components include a controller. Various sensors, controllers and actuators form a closed-loop control system. The actuators include: a three-axis loading component, a mixing component, an injection component, an additive component and a backflow metering component, which can control the three-axis pressure, the mixing speed of the leaching liquid, the injection speed of the leaching liquid, the additive dosage and the opening and closing of the backflow component.

[0084] Embodiment 2: Method embodiment

[0085] Accordingly, the present invention also proposes a physical simulation method for in situ rock fracturing and permeability enhancement and in situ leaching, comprising the following steps:

[0086] S1. Experimental preparation:

[0087] S1.1, press Figure 1 The physical simulation device for in situ rock fracturing, permeability enhancement and in situ leaching required for construction is shown;

[0088] S1.2. Prepare a sample 8 with a known uranium content, set a pre-buried tube 83 and a prefabricated slot 82 in the sample 8 according to the experimental requirements, and use the same batch of samples 8 to measure the basic physical parameters of the sample 8, including uniaxial compressive strength, uniaxial tensile strength, and permeability;

[0089] S1.3, place the pressure pillow 17, the vertical end pad 152 and the sample 8 on the lower tray 162 in sequence, then arrange the monitoring probe 61 and install the friction-reducing plate according to the predetermined plan, then install the end pads 15 on the four sides, and finally apply the sealing coating on the exposed area of ​​the sample 8 to isolate the sample 8 from the confining pressure medium during the experiment. The sealing coating needs to cover the boundary of the contact surface between the end pad 15 and the sample 8;

[0090] S1.4, after the glue is cured, use the vacuum pump 51 to evacuate the sample 8 from the injection hole and the embedded pipe 83, and only after the sealing of the sample 8 after the glue coating is tested to be qualified can the next step of the experiment be carried out;

[0091] S1.5. Connect the signal line of the monitoring probe, check the monitoring probe, and record the problematic measuring points;

[0092] S1.6, start the mixing component, prepare the ground immersion liquid required for the simulation experiment in the mixing container group 27, and fill the double-cylinder constant speed and constant pressure injection pump with the ground immersion liquid, then close all the stop valves in the system, and add additives to the high-pressure storage tank 41; start the multi-parameter acquisition component 6 and the control component 7.

[0093] For further optimization, for experiments with higher temperatures, a heating box is used to preheat the sample 8 to be used so as to shorten the heating time of the sample 8 in the pressure chamber 12 .

[0094] After further optimization, the test methods for permeability and rock strength comply with GB / T 28912-2012 and GBT50266-2013 standards. The number of rock samples tested is not less than 5, and the average value of the 5 test results is taken as the permeability and strength value of sample 8.

[0095] S2. Equipment self-test:

[0096] Check whether the functions of each component are normal and whether the sensors in key parts are normal.

[0097] For further optimization, all sensors should be inspected and calibrated every six months, the injection pump flow should be calibrated every six months, and the monitoring probes and collectors should be inspected and calibrated before each experiment.

[0098] S3, sample 8 installation:

[0099] S3.1. Install the lower end cover sealing ring 1321, the monitoring signal line through-cabin joint 1322 and the pressurized pipe through-cabin joint 1323, etc., and then install the lower end cover 132 to the lower part of the pressure chamber 12;

[0100] S3.2. After installing the annular pad 163 and the lower pad 164, install two pairs of arc wedge-shaped pads 141 in the horizontal direction, connect the cabin signal line 62 on the lower end cover 132 to the cable strip, and connect the pressure pillow high-pressure pipe 174;

[0101] S3.3, hoist the lower tray 162, the vertical pressure pillow 17, the end pad 161 and the sample 8 to the center of the lower pad 164 in the pressure chamber 12, then install the horizontal pressure pillow 17 and the square wedge pad 142, then connect each pressure pillow 17 to the pressure pillow high-pressure pipe 174, adjust the height of the sample 8 to the predetermined position through the pressure pillow 17 under the sample 8, and then adjust the horizontal position of the sample 8 through the wedge pad 142, and control the overall installation error within 1mm;

[0102] S3.4, install the flat seal 1611 and the upper end cover seal 1311 on the upper gasket 161, and then install the upper gasket 161, the upper end cover 131, the shear ring gasket 133, and the shear ring 134 on the sample 8 in sequence. After the pressure chamber 12 is assembled, check each monitoring probe and record the abnormal probes;

[0103] S3.5, connect the hydraulic servo system 11 and the three-axis pressure chamber 12, open the stop valve 1312 of the upper end cover exhaust hole, connect the upper end cover exhaust hole 1313 to the atmosphere, fill the pressure pillow 17 with hydraulic oil, and then fill the hydraulic pressure into the internal liquid filling space 124 of the pressure chamber 12 through the confining pressure oil circuit 114. When the hydraulic oil is filled, close the stop valve 1312; connect the return flow metering component 5 and the return flow outlet pipe 521.

[0104] S4. In-situ rock stress application:

[0105] S4.1. First, apply vertical stress to 2MPa-5MPa at a pressurization rate of 20MPa / min, fix the sample 8, and provide pressure to the sealing structure between the upper pads. Then, apply a smaller horizontal pressure. After the pressure stabilizes, apply confining pressure. Subsequently, the three-dimensional stress and confining pressure are simultaneously increased to the target pressure at a pressurization rate of 10MPa / min. At this time, the three-dimensional stress of the sample 8 is: σ i =α i ·P i , i = x, y, z, where: σ i is the stress of the sample in the 8i direction, unit: MPa, α i is the force transmission coefficient of the pressure pillow 17 in the i direction, P i is the internal pressure of the pressure pillow 17 in the i direction, in MPa; during the loading process, the internal pressure of the pressure pillow 17 is kept greater than the confining pressure; the pressure chamber 12 is heated as a whole by wrapping a heat preservation heating jacket outside the pressure chamber 12; after the pressure is stabilized, observe whether there is confining pressure liquid flowing out of the injection hole on the end pad and the embedded pipe 83 in the sample 8. If there is liquid flowing out, terminate the experiment and install the next sample 8;

[0106] S4.2. Monitor and record the status of sample 8, including the wave velocity, initial strain at each measuring point, resistance value, etc. of sample 8, as a baseline for subsequent monitoring.

[0107] Further optimization is performed. There is a certain difference between the internal pressure of the pressure pillow 17 and its actual output stress on the surface of the sample 8. Before the experiment, the output stress of each pressure pillow 17 within the operating pressure range is calibrated.

[0108] For further optimization, when the stress of more than 31.5 MPa needs to be applied to the internal pressure and the confining pressure of the pressure pillow 17, it is necessary to increase the pressure with the help of a hydraulic booster, drive the hydraulic oil between the plunger and the piston through a pump, and use the pressure difference to increase the oil pressure, thereby achieving the purpose of boosting.

[0109] S5. Physical simulation of reservoir transformation:

[0110] S5.1. Fix the disturbance load simulation device by using the disturbance load device fixing hole 121, embed the shock wave generating device at the bottom of the embedded pipe 83, release the cylindrical shock wave after excitation, simulate the reservoir transformation, i.e. the homogenization fracture network 81 construction process, after the disturbance load is applied, remove the disturbance load simulation device, and connect the injection assembly 3, the additive assembly 4 and the injection pipe 320;

[0111] S5.2, open the stop valves 273, 316, 45, 46, 571, turn on the screw pump motor 43, turn on the double-cylinder constant speed and constant pressure injection pump, set the ground leaching liquid injection flow rate to Q, pump additives into the seam network 81, use the liquid collecting tank to collect the waste liquid discharged from the return liquid pipeline 521, and after the above operations are completed, turn off the screw pump motor 43 and the double-cylinder constant speed and constant pressure injection pump, and close all the stop valves.

[0112] S6. Physical simulation of in-situ leaching process:

[0113] S6.1. Start the mixing component, injection component 3, backflow component 5 and control component 7, set the in-situ leaching solution concentration, injection pressure and production pressure according to the target values, inject the in-situ leaching solution into the sample 8, produce the uranium ore in the sample 8 through chemical reaction, use the gas flow meter group 542 and the liquid flow meter group 543 in the backflow metering component to record the gas flow and liquid flow in the produced material, and use the gas sampler 55 and the liquid sampler 56 to collect the produced gas and liquid for inspection and analysis; the theoretical production rate of the in-situ leaching solution is: where ρ 1 - Sample density, unit: kg / m 3 , L-specimen side length, unit: m, C 1 - sample uranium mass fraction, V-flowback volume, unit: m 3 , C 2 The uranium mass fraction is calculated based on the test results, ρ 2 -Density of the return fluid, unit: kg / m 3 ;

[0114] S6.2, open the stop valves 316 and 317, start the back pressure valve 53, open the stop valve 58, set the pressure of the back pressure valve 53, start the injection assembly 3, set the injection flow rate, and continuously inject the ground soaking liquid until the pressure value of the injection port pressure gauge 319 fluctuates less than 1MPa / min, and record the value of the injection port pressure gauge; use Darcy's formula to calculate the equivalent permeability coefficient of the reservoir at this time: Where: P 1 -Injection pressure, unit: MPa, P 2 - back pressure, μ-in-situ leaching fluid viscosity, unit: mPa·s; Q-in-situ leaching fluid flow rate, unit: cm 3 / s, L-side length of the sample, A-cross-sectional area of ​​the ground leaching liquid passing through the sample, unit: cm 2 ;

[0115] S6.3. During the experiment, the monitoring component records the sound, light, electricity, temperature, pressure, flow and other data observed during the simulation process; by analyzing the sound, light, electricity, temperature, pressure, flow and other data during the reservoir transformation and exploitation process, and inverting the multi-parameter monitoring signal to study the evolution process of the fracture network 81 before reservoir transformation and during exploitation, the main factors affecting the reservoir exploitation efficiency can be further clarified, and a quantitative evaluation of different factors can be made.

[0116] S7, unloading and post-processing of sample 8:

[0117] S7.1. After closing all stop valves, close the mixing component, injection component 3, flowback component 5, and multi-parameter acquisition component 6, and then open the stop valve 571 to guide the flowback liquid in the pressure relief process to the liquid collecting tank 57;

[0118] S7.2. Use the servo hydraulic system 11 to synchronously reduce the internal pressure of the pressure pillow 17 and the confining pressure. Set the pressure reduction rate to 30 MPa / min. The target value of the internal pressure of the pressure pillow 17 is 2 MPa, and the target value of the confining pressure is 0 MPa. After reaching the target, open the stop valve 1312, extract the confining pressure fluid from the confining pressure oil circuit 114, and unload the internal pressure of the pressure pillow 17. The pressure reduction rate is 30 MPa / min. During the unloading process, keep the confining pressure value lower than the internal pressure value of the pressure pillow 17.

[0119] S7.3. Remove the high-pressure pipe connected to the injection pipe 320, remove the shear ring 134, then hoist the shear ring pad 133, the upper end cover 131, and the upper pad 161 out of the pressure chamber 12, disconnect the monitoring signal line and the high-pressure pipe of the pressure pillow 17, then remove the horizontal square wedge pad 142 and the horizontal flat pressure pillow 17, and finally hoist the sample 8 together with the end pad, the lower pressure pillow 17 and the lower pad 164 out of the pressure chamber 12, and remove the end pad on the surface of the sample 8;

[0120] S7.4. Clean the injection assembly, mixing assembly, additive assembly and flowback assembly, and close the control assembly; send sample 8 to the analysis center for analysis, and perform the following operations: take photos, scan the surface morphology of sample 8, reconstruct the seam network 81 by CT scanning, reconstruct the seam network 81 by nuclear magnetic resonance scanning, reconstruct the seam network 81 by ultrasonic scanning, fracture analysis, post-cutting analysis, component analysis, etc.

[0121] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0122] The order of execution of each step in the above embodiment does not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0123] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A physical simulation device for in situ rock fracturing, permeability enhancement and in situ leaching, comprising a triaxial loading assembly, characterized in that: It also includes a mixing component, an injection component, an additive component, a flowback metering component and a test sample; The triaxial loading assembly includes a hydraulic servo system, a pressure chamber and a pressure pillow. The sample is installed in the pressure chamber. The pressure pillows are respectively arranged below and on four sides of the sample. The original rock stress on the sample is provided by the pressure pillows in three directions and the liquid confining pressure in the liquid-filled space inside the pressure chamber. The internal pressure of the pressure pillow and the liquid confining pressure are provided by the hydraulic servo system. The mixing assembly includes a dissolved oxygen generator, a CO2 booster and a mixing container group, wherein the outlets of the dissolved oxygen generator and the CO2 booster are respectively connected to the inlet of the mixing container group, and the ground leaching solution is prepared by uniformly mixing the oxygen-containing solution and CO2 through the mixing container group, and the outlet of the mixing container group is connected to the inlet of the injection assembly; The outlet of the injection assembly is connected to the inlet of the additive assembly through a branch, and the outlet of the injection assembly is also connected to the injection pipe of the triaxial loading assembly through another branch, and the injection pipe is connected to the pre-buried pipe of the sample; The inlet of the additive assembly is connected to the outlet of the injection assembly, and the outlet of the additive assembly is connected to the injection pipe of the triaxial loading assembly, and different additives are added into the sample through the additive assembly; The backflow metering assembly includes a vacuum pump, a backflow liquid outlet pipe, a solid separator, a back pressure valve, a gas-liquid separator, a gas flow meter group and a liquid flow meter group; the vacuum pump is connected to the injection pipe through a pipeline; the backflow liquid in the pressure chamber is discharged through the backflow liquid outlet pipe, the solid separator, the back pressure valve, and the gas-liquid separator are sequentially arranged on the backflow liquid outlet pipe, and the gas-liquid separator is divided into a gas pipeline and a liquid pipeline, the gas flow meter group is installed on the gas pipeline, and the liquid flow meter group is installed on the liquid pipeline.

2. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 1, characterized in that: The hydraulic servo system comprises an X-direction oil circuit, a Y-direction oil circuit, a Z-direction oil circuit and a confining pressure oil circuit, wherein the X-direction oil circuit is connected to the pressure pillow below the sample, the Y-direction oil circuit is connected to the pressure pillows on the left and right sides of the sample, the Z-direction oil circuit is connected to the pressure pillows on the front and rear sides of the sample, and the confining pressure oil circuit is connected to the liquid-filled space inside the pressure chamber; when loading, the internal pressure value of the pressure pillow is greater than the liquid confining pressure value.

3. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 1, characterized in that: The pressure pillow comprises a pressure pillow shell, an elastic lining and granular material. The elastic lining is arranged inside the pressure pillow shell, and the granular material is filled in the elastic lining.

4. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 1, characterized in that: The backflow metering component also includes a liquid sampler and a gas sampler. The liquid sampler is arranged on a branch line between the solid separator and the back pressure valve, and the gas sampler is arranged on a pipeline after the gas flow meter group.

5. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 1, characterized in that: The dissolved oxygen generating device comprises an oxygen gas source, an oxygen solution stirring container and a water source, wherein the outlets of the oxygen gas source and the water source are respectively connected to the inlet of the oxygen solution stirring container, and the outlet of the oxygen solution stirring container is connected to the inlet of the mixing container group; the CO2 boosting device comprises a CO2 gas source, a CO2 boosting pump, a CO2 storage tank and a CO2 metering pump which are sequentially connected through pipelines, and the outlet of the CO2 metering pump is connected to the inlet of the mixing container group.

6. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 5, characterized in that: The outlet pipeline of the oxygen gas source is provided with an oxygen pressure regulating valve, an oxygen pressure gauge and an oxygen stop valve; the oxygen solution stirring container is provided with an oxygen content sensor and a liquid level meter (212); the outlet pipeline of the oxygen solution stirring container is provided with an oxygen solution metering pump and a stop valve (216).

7. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 5, characterized in that: The inlet pipeline of the CO2 storage tank is provided with a CO2 pressure gauge, the outlet pipeline of the CO2 storage tank is provided with a CO2 safety valve and a stop valve (253), and the outer shell of the CO2 storage tank is provided with a thermal insulation heating jacket; the outlet pipeline of the CO2 metering pump is provided with a CO2 pressure regulating valve, a CO2 pressure gauge and a stop valve (263), and the outer shell of the CO2 metering pump is provided with a thermal insulation heating jacket.

8. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 5, characterized in that: A liquid level meter (272) and a heat preservation and heating jacket are arranged outside the mixing container group, and a stop valve (273) is arranged on the outlet pipeline of the mixing container group.

9. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 1, characterized in that: The injection assembly adopts a double-cylinder constant-speed constant-pressure injection pump, which includes a first single pump 321 and a second single pump 322 arranged in parallel. The inlet pipeline of the first single pump 321 is provided with a stop valve (312), and the outlet pipeline is provided with a stop valve (313). The inlet pipeline of the second single pump 322 is provided with a stop valve (314), and the outlet pipeline is provided with a stop valve (315). The two single pumps can independently perform liquid suction and liquid discharge actions.

10. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 1, characterized in that: The additive assembly includes a high-pressure storage tank, a screw pump and a screw pump motor. The lower funnel outlet of the high-pressure storage tank is connected to the outlet of the injection assembly. The additive in the high-pressure storage tank falls to the outlet under its own weight and mixes with the ground leaching liquid. The screw pump motor rotates the screw pump to pump the mixed ground leaching liquid into the cracks inside the sample.

11. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 1, characterized in that: The triaxial loading assembly also includes an end pad block arranged around the sample, and a space for arranging various monitoring probes is reserved in the end pad block to meet the arrangement requirements of acoustic wave probes, strain gauges, optical fibers and electrodes, and support the arrangement of array-type acoustic wave probes; a water distribution trough and a pad diversion hole are also provided in the end pad block to divert the ground immersion liquid flowing through the embedded pipes and seam networks in the sample out of the pressure chamber.

12. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 11, characterized in that: The three-axis loading assembly also includes an end cover assembly, which includes an upper end cover, a lower end cover, a shear ring gasket and a shear ring. The upper end cover is installed at the upper end of the pressure chamber, and the upper end cover is provided with an upper end cover sealing ring along the circumferential direction; the lower end cover is installed at the lower end of the pressure chamber, and the lower end cover is provided with a lower end cover sealing ring along the circumferential direction; the shear ring is installed on the inner wall of the pressure chamber and is located above the upper end cover, and the shear ring gasket is installed between the upper end cover and the shear ring.

13. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 12, characterized in that: The triaxial loading assembly also includes a supporting pad assembly, which includes an upper pad, a lower tray, an annular pad and a lower pad. The upper pad is installed between the vertical end pad and the upper end cover, the lower tray is installed at the lower end of the pressure pillow below the sample, the lower pad is installed between the lower tray and the lower end cover, and the annular pad is installed between the outer periphery of the lower pad and the inner wall of the pressure chamber.

14. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 13, characterized in that: The centers of the upper end cover, the upper pad, and the vertical end pad are respectively opened with holes for applying engineering disturbance loads, and the upper end of the pressure chamber is provided with a fixing hole for the disturbance load device; plane seals are respectively arranged between the upper end cover and the upper pad, and between the upper pad and the vertical end pad, to prevent the confining pressure liquid from seeping out from the gaps between the pads.

15. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 1, characterized in that: The three-axis loading assembly also includes a wedge pad assembly arranged between the pressure pillow and the inner wall of the pressure chamber, the wedge pad assembly includes a circular arc wedge pad and a square wedge pad, the circular arc wedge pad is installed on the inner wall of the pressure chamber, and the square wedge pad is installed between the circular arc wedge pad and the pressure pillow.

16. The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device according to claim 11, characterized in that: The in-situ rock fracturing permeability enhancement and in-situ leaching physical simulation device also includes a multi-parameter acquisition component, which includes a variety of monitoring probes and acquisition instruments and signal cables connecting the monitoring probes and the acquisition instruments; The various monitoring probes are installed in the end pad, and the types of the various monitoring probes include acoustic emission probes, ultrasonic probes, strain gauges, optical fibers, and electrode acceleration sensors. The types of collectors include acoustic emission collection cards, acoustic wave collection cards, strain gauges, optical fiber instruments, resistivity collection instruments, and acceleration collection instruments.

17. A physical simulation method for in situ leaching of rock, characterized in that: The physical simulation device for in situ rock fracturing, permeability enhancement and in situ leaching mining according to any one of claims 1 to 16 is used, comprising the following steps: Use a vacuum pump to evacuate the sample from the injection hole and the embedded pipe; Start the mixing component, prepare the ground leaching liquid required for the simulation experiment in the mixing container group, and fill the ground leaching liquid with the double-cylinder constant speed and constant pressure pump in the injection component, then close all the stop valves, and add additives to the additive component; In-situ rock stress application: first apply vertical stress to 2MPa-5MPa, fix the sample, and then apply 2MPa-5MPa horizontal pressure. After the pressure stabilizes, apply confining pressure, and then simultaneously increase the three-dimensional stress and confining pressure to the target pressure; during the loading process, keep the internal pressure of the pressure pillow greater than the confining pressure; heat the pressure chamber as a whole by wrapping a heat-insulating heating jacket outside the pressure chamber; after the pressure is stabilized, observe whether there is confining pressure liquid flowing out of the injection hole on the end pad and the embedded pipe in the sample. If there is liquid flowing out, terminate the experiment and install the next sample until there is no liquid flowing out; monitor and record the state of the sample, including the acoustic wave velocity of the sample, the initial strain of each measuring point, and the resistance value, as the subsequent monitoring baseline; Physical simulation of reservoir transformation: fix the disturbance load simulation device on the pressure chamber, embed the shock wave generator at the bottom of the embedded pipe hole, release the cylindrical shock wave after excitation, simulate the reservoir transformation, i.e. the homogenization fracture network construction process, after the disturbance load is applied, remove the disturbance load simulation device; open the stop valves related to the injection component and the additive component, set the injection flow rate of the in-situ leaching liquid, pump the additive into the fracture network, use the liquid collecting tank to collect the waste liquid discharged from the return liquid pipeline, and close all the stop valves after the above operations are completed; Physical simulation of in-situ leaching process: start the mixing component, injection component, backflow metering component and control component, set the in-situ leaching solution concentration, injection pressure and production pressure according to the target values, inject the in-situ leaching solution into the sample, produce the uranium ore in the sample through chemical reaction, use the gas flow meter group and liquid flow meter group in the backflow metering component to record the gas flow and liquid flow in the produced material respectively, and use the gas sampler and liquid sampler to collect the produced gas and liquid for inspection and analysis; start the back pressure valve, set the back pressure valve pressure, start the injection component, set the injection flow, and continuously inject the in-situ leaching solution until The pressure value fluctuation of the injection port pressure gauge is less than 1MPa / min, and the value of the injection port pressure gauge is recorded; the Darcy formula is used to calculate the equivalent permeability of the reservoir at this time; during the experiment, the sound, light, electricity, temperature, pressure, and flow data observed during the simulation process are recorded through a multi-parameter acquisition component; by analyzing the sound, light, electricity, temperature, pressure, flow and other data during the reservoir transformation and exploitation process, and inverting the multi-parameter monitoring signal to study the fracture network evolution process before reservoir transformation and during exploitation, the main factors affecting the reservoir exploitation efficiency can be further clarified, and a quantitative evaluation of different factors can be made.

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