Rock mass breaking method and system based on phase change fluid-rock mass coupling

Abstract

The application provides a rock mass breaking method and system based on phase change fluid-rock mass coupling, comprising: a phase change fluid supply module for supplying phase change fluid; a rock mass structure analysis module for obtaining spatial distribution parameters and mechanical parameters of a rock mass structure surface of a target rock mass; an energy release module comprising an in-hole energy concentrator and a multi-layer coupling structure jet nozzle, the in-hole energy concentrator being used for pressurizing the phase change fluid and setting the phase change fluid in a predetermined direction, and the multi-layer coupling structure jet nozzle being used for jetting the pressurized phase change fluid in the predetermined direction; and a process matching unit for determining process parameters of the energy release module according to characteristic parameters of the phase change fluid, spatial distribution parameters and physical and mechanical parameters of the natural structure surface of the target rock mass. Through the system, the transmission direction of the phase change fluid can be better controlled, and the fracturing effect of the phase change fluid is improved.

Description

Technical Field

[0001] This application belongs to the field of rock mass fracturing, and in particular relates to a rock mass fracturing method and system based on phase change fluid-rock mass coupling. Background Technology

[0002] In fields such as hard rock mining, unconventional oil and gas resource development, geothermal reservoir construction, and underground space engineering, efficient, safe, and controllable fracturing of deep or complex rock masses is a core technical challenge that restricts project progress, cost, and efficiency. Currently, the mainstream rock fracturing technologies in the industry are mainly divided into three categories: traditional explosive blasting technology, hydraulic fracturing technology, and phase transformation fracturing technology. Each type of technology has inherent defects that are difficult to overcome, and cannot meet the requirements for efficient, green, and controllable rock fracturing under complex geological conditions.

[0003] Traditional explosive blasting technology relies on the shock waves generated by explosive detonation to break up rock masses. Although it achieves high fragmentation strength, it has three major drawbacks: First, it poses extremely high safety risks. The storage, transportation, and use of explosives require strict administrative approval and control procedures, making it unsuitable for sensitive areas such as near residential areas, underground tunnels, and important structures. Second, it causes severe disturbance to the surrounding rock. The high-frequency, strong shock waves generated by the detonation can cause irreversible damage to the surrounding rock, easily inducing secondary disasters such as rockfall, surface subsidence, and rock bursts. Third, it has extremely poor controllability. The detonation energy is released spherically and disorderly, with an energy utilization rate of less than 30%. The fragment size is extremely uneven, significantly increasing the costs of subsequent loading, transportation, and secondary crushing.

[0004] Hydraulic fracturing technology, as a supplement to blasting technology, achieves rock breaking by injecting high-pressure water into the rock mass to induce fracture propagation. However, it has significant limitations: First, it consumes a huge amount of water resources, with the water consumption for fracturing a single cubic meter of rock mass reaching 10-20 m³, making it unsuitable for widespread application in arid and water-scarce areas. Second, it has poor adaptability to low-permeability rock masses, as high-pressure water has difficulty penetrating into the micro-fractures inside the rock mass, resulting in limited fracturing effect and a tendency to generate water-locking effects, damaging the seepage channels of oil and gas and geothermal reservoirs and reducing resource recovery rates.

[0005] Phase change fracturing technology, which utilizes liquid CO2, liquid nitrogen, liquid oxygen, and other phase change fluids, is a green, non-explosive rock breaking technology that has emerged in recent years. Its core principle involves injecting a low-temperature liquid fluid into the borehole, causing it to rapidly vaporize and undergo a phase change, generating high-pressure gas that expands hundreds of times in volume. This high-pressure gas is then used to break up the rock mass through quasi-static loading. This technology eliminates the risks associated with explosives, is environmentally friendly, and causes minimal disturbance to the surrounding rock. It has already seen initial applications in mining, underground engineering, and other fields.

[0006] However, phase transformation fracturing technology is still in its early stages of development, with four major technological bottlenecks that severely restrict its industrial application: First, the energy transfer efficiency is extremely low. Existing phase change fracturing technologies use ordinary jet nozzles without energy confinement structures. The expansion energy generated by phase change attenuates rapidly during transmission through heterogeneous, fractured rock masses, resulting in significant energy dissipation at the borehole opening and ineffective transmission to deep target areas. Industry measurement data shows that the energy efficiency of existing phase change fracturing technologies is less than 30%, and the effective range is only one-third of the borehole depth, failing to meet the requirements for fracturing deep rock masses.

[0007] Second, the energy release is completely disordered. Existing technologies cannot achieve directional guidance of phase change energy. Expansion energy is released randomly around the borehole, making it impossible to accurately identify and act on weak structural surfaces such as joints, bedding, and fractures in the rock mass. This results in extremely low energy utilization, small fragmentation range, irregular shape, and difficulty in forming a well-connected fracture network, which cannot meet engineering requirements such as volumetric fracturing and precise top cutting.

[0008] Third, it has poor adaptability to geological conditions. Different lithologies (granite, sandstone, shale, coal seams, etc.) and different geological structures (degree of fracture development, geostress state) have significantly different requirements for energy conduction and release. However, existing technologies lack systematic parameter optimization methods, and the selection of process parameters relies entirely on engineering experience, without forming a standardized design system. For high-strength hard rocks, existing parameters cannot provide sufficient energy focusing; for low-permeability soft rocks, they easily lead to excessive energy dissipation, resulting in extremely poor versatility.

[0009] Fourth, the energy accumulation mechanism is lacking. Existing phase transformation fracturing technology lacks secondary pressurization and energy focusing structures. The pressure waves generated by the phase transformation cannot be superimposed and multiplied, and the jet energy is not directionally guided. A large amount of energy is used to overcome the overall strength of the rock mass rather than to drive the fracture to extend along the weak surface, which further aggravates the ineffective dissipation of energy.

[0010] In summary, existing rock fracturing technologies all have insurmountable technical bottlenecks. The industry urgently needs a core technology that can achieve deep, accurate, and effective transmission and release of phase change expansion energy, solve the core problems of low energy transfer efficiency, disordered release, and poor adaptability of existing phase change fracturing technologies, and promote the industrial upgrading of phase change fracturing technologies. Summary of the Invention

[0011] In view of this, this application provides a rock mass fracturing method and system based on phase change fluid-rock mass coupling, which aims to solve one or more of the above problems.

[0012] In a first aspect, this application provides a rock mass fracturing system based on phase change fluid-rock mass coupling, comprising: Phase change fluid supply module, used to supply phase change fluid; The rock mass structure analysis module is used to obtain the spatial distribution parameters and mechanical parameters of the rock mass structure planes of the target rock mass. The energy release module includes an in-orifice energy collector and a multi-layer coupled jet nozzle. The in-orifice energy collector is used to pressurize the phase change fluid and set the phase change fluid in a predetermined direction. The multi-layer coupled jet nozzle is used to eject the pressurized phase change fluid in a predetermined direction. And a process matching unit, used to determine the process parameters to be used by the energy release module based on the characteristic parameters of the phase change fluid, the spatial distribution parameters of the natural structural surfaces of the target rock mass, and the physical and mechanical parameters.

[0013] Optionally, the multi-layer coupled jet nozzle includes: The inner flow channel and the outer annular flow channel surrounding the inner flow channel; the inner flow channel is used to transport phase change fluid to form the main jet, and the outer annular flow channel is used to transport high-pressure medium to form an energy curtain that surrounds the main jet.

[0014] Optionally, the in-orifice energy concentrator includes: The reflective chamber and the guide vanes; the reflective chamber pressurizes the phase change fluid based on the pressure wave multiplication effect; the guide vanes are used to direct and focus the pressurized main jet to the target area.

[0015] Secondly, this application provides a rock mass fracturing method based on phase change fluid-rock mass coupling, applied to the rock mass fracturing system based on phase change fluid-rock mass coupling as described above, including: Obtain the characteristic parameters of the phase change fluid, the spatial distribution parameters and mechanical parameters of the rock mass structure plane of the target rock mass; Based on the spatial distribution parameters and mechanical parameters of the rock mass structure planes of the target rock mass, a three-dimensional mesh model of the target rock mass is established, and the global energy impedance matrix of the three-dimensional mesh model is calculated. Calculate the fracturing energy of rock mass structural planes, and use the fracturing energy of rock mass structural planes as an indicator to determine several rock mass structural planes as candidate structural planes; The preset nozzle position is determined, and combined with the physical property parameters of the phase change fluid, the optimization algorithm is used to determine the path with the minimum total energy attenuation from the preset nozzle position to several candidate structural surfaces, and a set of candidate paths is obtained. Then, through fluid-structure interaction analysis, the connectivity of several candidate paths in the set of candidate paths is determined, and the target path is obtained. The phase change fluid is controlled to be delivered along the target path to the target area of ​​the target rock mass, thereby breaking up the target rock mass; Data on rock mass fracture, fracture propagation, and borehole pressure changes are collected from the target rock mass. The parameters used by the energy release module are adjusted based on the rock mass fracture data, fracture propagation data, and borehole pressure distribution data.

[0016] Optionally, the calculation process for the global energy impedance matrix of the three-dimensional mesh model is as follows: Calculate the energy attenuation coefficient at each element in the three-dimensional mesh model; where the energy attenuation coefficient of the intact rock mass is determined based on the rock mass strength and density, and the energy attenuation coefficient of the rock mass structural plane is determined based on the structural plane attenuation reduction coefficient and the energy attenuation coefficient of the intact rock mass; Based on the energy attenuation coefficient and perimeter of each element in the 3D mesh model, the impedance value of each element in the 3D mesh model is determined, and the global energy impedance matrix of the 3D mesh model is obtained.

[0017] Optionally, the calculation process for the fracture energy of the rock mass structural plane is as follows: Based on the fracture toughness and elastic modulus of the rock mass structural plane, determine the tensile fracturing energy per unit area of ​​the rock mass structural plane. The total critical tensile fracturing energy of the rock mass structural plane is determined based on the effective working area of ​​the rock mass structural plane and the tensile fracturing energy per unit area of ​​the rock mass structural plane. The shear strength of the rock mass structural surface is determined based on the cohesion of the rock mass structural surface, the normal stress of the rock mass structural surface, and the internal friction angle of the rock mass structural surface. Based on the shear strength of the rock mass structural surface and the boundary shear displacement of the rock mass structural surface, determine the shear fracture energy per unit area of ​​the rock mass structural surface; The total critical shear fracture energy of the rock mass structural surface is determined based on the shear fracture energy per unit area of ​​the rock mass structural surface and the effective working area of ​​the rock mass structural surface. The fracture energy of the rock mass structural plane is determined based on the total critical tensile fracture energy and the total critical shear fracture energy of the rock mass structural plane.

[0018] Optionally, the objective function used by the optimization algorithm is: In some embodiments, the objective function used by the three-dimensional optimization algorithm is:

[0019] In the formula: Energy efficiency; For the first Effective interaction energy at each candidate structural surface; Inject total energy into the phase change fluid.

[0020] Optionally, the process of adjusting the parameters used by the energy release module based on rock mass fracture data, fracture propagation data, and borehole pressure distribution data includes: The fracture propagation rate and fracture propagation degree are calculated based on the fracture propagation data. The deviation rate of the energy release path was calculated based on the pressure distribution data inside the borehole; Energy release efficiency was calculated based on rock mass fracture data; The parameters used in the energy release module are adjusted based on the fracture propagation rate and fracture propagation extent, the deviation rate of the energy release path, and the energy release efficiency.

[0021] Thirdly, this application provides an electronic device, including a rock mass fracturing system based on phase change fluid-rock mass coupling as described in any of the preceding claims.

[0022] Fourthly, this application provides a computer-readable storage medium storing at least one piece of program code, which is executed by a processor to implement the rock mass fracturing method based on phase change fluid-rock mass coupling as described in any of the preceding claims.

[0023] The beneficial effects of the technical solution provided in this application include: 1. Theoretical and methodological innovation: A full-chain phase transformation fracturing theory and method of "rock mass structural surface identification - energy conduction path optimization - directional focused release" was proposed. This breaks the inherent mode of disordered "flooding" energy release in traditional phase transformation fracturing technology and realizes a fundamental transformation from "blind rock breaking" to "precise targeted rock breaking". It solves the core problem of disordered energy release and low utilization rate of existing technologies from the root, and fills the industry gap in directional phase transformation fracturing theory and method.

[0024] 2. Core Equipment Innovation: A pioneering two-stage pressurization and focusing actuator, combining a multi-layered coupled jet nozzle and an in-orifice energy concentrator, simulates the physical process of "rocket engine nozzle constraint + optical lens focusing," achieving two-stage pressurization and directional focusing of phase change expansion energy. Specifically, the multi-layered coupled jet nozzle, through the constraint of the outer energy curtain, improves energy transfer efficiency by over 40%; the in-orifice energy concentrator, through the pressure wave superposition effect of the reflection chamber, increases the peak pressure after secondary pressurization by 60%-100% compared to traditional jets. Combined with adjustable guide vanes, this achieves precise directional energy release, completely overcoming the technical bottlenecks of low energy transfer efficiency and inability to conduct energy deep into the body in existing technologies.

[0025] 3. Enhanced Intelligent Adaptability: An energy transfer path optimization model based on a rock mechanics-fluid mechanics coupled algorithm was constructed, incorporating a comprehensive lithology parameter database. This represents a leap from "experience-based judgment" to "scientific quantitative optimization" of process parameters. The model can automatically match the optimal process scheme based on rock mass parameters of different lithologies and geological structures, significantly improving the technology's adaptability to complex geological conditions. This overcomes the shortcomings of existing technologies, such as poor versatility and reliance on experience, and establishes a standardized phase transformation fracturing design and construction system.

[0026] 4. Significantly Improved Rock Breaking Efficiency and Energy Utilization: Through a two-stage pressurization constraint and relay-focused release technology, the rapid attenuation of phase change energy in complex rock masses is effectively overcome, increasing the effective energy range by more than 50% compared to traditional technologies, thus meeting the needs of deep rock mass fracturing. The energy release direction is precisely matched to the weak structural planes of the rock mass, concentrating over 70% of the phase change expansion energy onto the target fracturing area. The effective energy utilization rate is 2-3 times higher than traditional phase change fracturing technology and more than 1.5 times higher than traditional explosive blasting technology. This invention can induce tensile-shear composite fracturing along natural structural planes in the rock mass, forming a complex fracture network with good connectivity and uniform distribution, resulting in uniform fragment size and significantly reducing subsequent operation costs. In granite hard rock fracturing scenarios, phase change fluid consumption can be reduced by more than 40%, and in roadway fault pre-fracture scenarios, tunneling efficiency can be increased by more than 50%.

[0027] 5. Excellent Safety and Environmental Performance: This invention utilizes a non-explosive phase change fluid, eliminating the risk of detonation and the need for cumbersome explosive approval and control procedures. The entire process of storage, transportation, and use is safe and controllable, making it suitable for rock fracturing operations in sensitive areas. The phase change fluid can be recycled or naturally volatilized after phase change, producing no toxic or harmful gases and causing no pollution to soil or groundwater, meeting the requirements of green mine construction and environmental protection. Compared to hydraulic fracturing technology, it requires no large amounts of water, completely avoiding the water-locking effect, making it particularly suitable for arid and water-scarce areas and low-permeability reservoir stimulation. Furthermore, the phase change fracturing process of this invention is a quasi-static loading process with an action time of approximately 200 milliseconds. Compared to the microsecond-level detonation process of explosive blasting, this can reduce the deformation of the surrounding rock in the tunnel by 20%-30%, significantly reducing disturbance to the surrounding rock and lowering the risk of secondary disasters.

[0028] 6. Wide Applicability and High Industrialization Value: This invention is adaptable to various rock types, including granite, sandstone, shale, and coal seams. It is widely applicable to various rock fracturing projects such as hard rock mining, ore body pre-fracture, unconventional oil and gas reservoir stimulation, geothermal reservoir construction, underground engineering excavation, coal mine roof cutting and pressure relief, and fault pre-fracture. It only requires optimizing process parameters through an intelligent control unit to adapt to different engineering scenarios, without the need for large-scale system modifications, demonstrating extremely high versatility. This invention solves the core pain points of existing phase transformation fracturing technologies, significantly improving engineering efficiency, reducing construction costs, and ensuring operational safety. It has broad prospects for industrialization and significant economic, social, and environmental benefits. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 A schematic diagram of a rock mass fracturing system based on phase change fluid-rock mass coupling provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a multi-layer coupled jet nozzle provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of an in-orifice energy collector provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a guide vane provided in one embodiment of this application; Figure 5 This is a flowchart of a rock mass fracturing method coupled with phase change fluid in one embodiment of this application; Figure 6 A schematic diagram comparing the rock mass fracture network formed by the traditional phase transformation fracturing technique and the method of the present invention, as provided in an embodiment of this application; Figure 7 This is a structural block diagram of an electronic device provided in an embodiment of this application.

[0031] The attached figures are labeled as follows: 1: Phase change fluid supply module; 11: Insulated storage tank; 12: High-pressure plunger booster pump; 13: Filter; 14: Flow control valve; 2: Rock mass structure analysis module; 21: Ground penetrating radar; 22: Borehole camera equipment; 23: Microseismic monitoring equipment; 24: Data acquisition terminal; 3: Energy release module; 31: Multi-layer coupled jet nozzle; 311: Inner flow channel; 312: Outer annular flow channel; 313: Energy curtain; 314: Phase change fluid main jet; 32: Energy collector in the orifice; 321: Reflection chamber; 322: Guide vane; 323: Sealing device; 4: Process matching unit; 41: PLC industrial controller; 42: Touch operation panel; 43: Data communication module; 44: Energy conduction path optimization model; 5: Injection string; 6: Drill hole; 7: Target rock mass; 8: Target structural plane; 9: Rock mass fracture monitoring equipment. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] Figure 1 This is a schematic diagram of a rock mass fracturing system based on phase change fluid-rock mass coupling, provided as an embodiment of this application. See also... Figure 1 ,include: Phase change fluid supply module 1, used to supply phase change fluid; Rock mass structure analysis module 2 is used to obtain the spatial distribution parameters and mechanical parameters of the rock mass structure planes of the target rock mass 7; The energy release module 3 includes a multi-layer coupled jet nozzle 31 and an in-hole energy collector 32, which are used to transfer phase change fluid into the target rock mass. And process matching unit 4, which is used to determine the optimal energy conduction path based on the characteristic parameters of the phase change fluid, the spatial distribution parameters and mechanical parameters of the natural structural surface of the target rock mass, and control the energy release module to transmit the phase change fluid to the target rock mass according to the optimal energy conduction path.

[0034] In this embodiment, the phase change fluid supply unit 1 is the core of the system's energy supply, used to realize the storage, pressurization and precise pumping of the low-temperature phase change fluid.

[0035] In some examples, the phase change fluid supply unit 1 includes: The insulated storage tank 11, the high-pressure plunger booster pump 12, the filter 13, and the flow control valve 14 are arranged in sequence and connected by matching pipelines.

[0036] In some examples, the insulated storage tank 11 may be designed with vacuum insulation to achieve long-term stable storage of cryogenic phase change fluids such as liquid oxygen, liquid CO2, and liquid nitrogen, thereby reducing the evaporation loss of the phase change fluid.

[0037] In some examples, the output pressure of the high-pressure plunger booster pump 12 is adjustable from 10MPa to 200MPa, and the output pressure can be precisely adjusted according to the rock mass crushing requirements.

[0038] In some examples, filter 13 is used to filter solid impurities in the phase change fluid to prevent clogging of the associated piping and the multi-layer coupled jet nozzle.

[0039] In some examples, the flow control valve 14 is used to precisely regulate the injection rate of the phase change fluid.

[0040] In some examples, during single-hole drilling operations, the phase change fluid supply unit 1 can be connected in series with a set of energy release modules 3. When multiple drilling operations need to be performed simultaneously, the phase change fluid supply unit 1 can be connected in parallel with multiple sets of energy release modules 3.

[0041] In this embodiment, the spatial distribution parameters and mechanical parameters of the rock mass structure surface of the target rock mass obtained by the rock mass structure analysis module 2 can serve as the core geological data support for the directional release of energy.

[0042] In some examples, rock mass structure analysis module 2 includes: 21. Ground-penetrating radar, 22. Borehole camera equipment, 23. Microseismic monitoring equipment, and 24. Data acquisition terminal.

[0043] In some examples, the ground-penetrating radar 21 is used to detect the spatial distribution of shallow to intermediate structural planes in a rock mass.

[0044] In some examples, the performance specifications of the ground-penetrating radar 21 are: maximum detection depth greater than or equal to 50m, and resolution less than or equal to 0.1m.

[0045] In some examples, the borehole camera device 22 is used to acquire structural details of the rock mass inside the borehole and accurately identify the degree of development and spatial orientation of fractures and joints inside the borehole.

[0046] In some examples, the microseismic monitoring device 23 is used to acquire micro-fracture signals inside the rock mass in real time and invert the stress distribution and mechanical properties of the rock mass.

[0047] In some examples, the data acquisition terminal 24 is used to integrate and analyze geological and mechanical data acquired by various devices, generate three-dimensional distribution maps of rock mass structural surfaces and mechanical parameter reports, and provide basic data for energy conduction path optimization.

[0048] In this embodiment, the energy release module 3 is the core working component of the system, used to realize multi-stage pressurization, directional focusing and efficient conduction of phase change energy.

[0049] In some examples, the energy release module 3 includes: The multi-layered coupled jet nozzle 31 and the in-orifice energy collector 32 work together to complete the two-stage pressurization and directional guidance of energy.

[0050] In some examples, the multi-layer coupled jet nozzle 31 is installed at the end of the injection string 5 and is lowered into the borehole 6 along with the string. It is a coaxial structure with at least two nested flow channels, used to deliver the phase change fluid to the target structural surface 8.

[0051] The inner flow channel 311 is used to transport high-speed phase change fluid to form the main jet 314, and the outer annular flow channel 312 is used to inject high-pressure gas or low-viscosity liquid to form an energy curtain 313 that surrounds the main jet.

[0052] See Figure 2 In some examples, the inner flow channel 311 has an inlet diameter of 4 mm to 8 mm, the outer annular flow channel has a width of 1 mm to 3 mm, the length ratio of the inner flow channel 312 to the outer annular flow channel is 0.7 to 0.8, and the diameter ratio is 2.5 to 2.7.

[0053] In some examples, the multi-layer coupled jet nozzle 31 can form a coupling constraint on the main jet through the outer energy curtain, which greatly reduces the radial diffusion of the main jet at the orifice, avoids energy dissipation caused by premature collision between the jet and the borehole wall, and achieves efficient energy conduction and initial accumulation to the depth of the borehole.

[0054] See Figure 3 In some examples, the in-hole energy collector 32 is a pre-installed or expandable mechanical / hydraulic sealing device that can be adapted to borehole diameters of 50mm to 150mm. It is equipped with a reflection chamber 321, an angle-adjustable guide vane 322 and a sealing device 323, and can be placed at a predetermined position within ±0.5m of the target structural surface inside the borehole.

[0055] In some examples, the reflection chamber 321 adopts a spherical or cylindrical structure with an inner diameter of 20-50mm, which allows the pressure wave generated by the jet impact to be reflected and superimposed multiple times in the chamber, achieving a multiplication effect of the pressure wave and completing the secondary pressurization of energy.

[0056] See Figure 4 In some examples, the number of the guide vanes 322 is 3 to 6, and the angle adjustment range is 30° to 60°. The guide direction can be adjusted according to the spatial orientation of the target structural surface to direct and focus the energy flow after secondary pressurization to the target structural surface.

[0057] In some examples, the in-orifice energy collector 32 is activated by the pressure or temperature of the phase change fluid jet reaching a set position. The trigger pressure is 15 MPa to 30 MPa, and the trigger temperature is -50°C to 0°C. After activation, the orifice is quickly sealed and the energy is collected.

[0058] In some examples, the process matching unit 4 is the core of the system's control and decision-making, used to achieve coordinated control of each unit and intelligent optimization of process parameters.

[0059] In some examples, process matching unit 4 includes: The system includes a PLC industrial controller 41, a touch operation panel 42, a data communication module 43, and a built-in energy conduction path optimization model 44.

[0060] In some examples, the PLC industrial controller 41 has an instruction response speed of ≤100ms, which is used to realize real-time closed-loop control of the phase change fluid supply and pressurization unit and the energy directional release execution unit.

[0061] In some examples, the touch control panel 42 is used for process parameter setting, real-time data display, and manual emergency operation.

[0062] In some examples, the data communication module 43 is used to enable high-speed data transmission and instruction synchronization between units.

[0063] In some examples, the energy conduction path optimization model 44 is used to determine the process parameters adopted by the energy release module based on the characteristic parameters of the phase change fluid, the spatial distribution parameters of the natural structural surfaces of the target rock mass, and the physical and mechanical parameters.

[0064] In some embodiments, the rock mass fracture monitoring device 9 can also detect the rock mass fracture effect, and then adjust the parameters adopted by the energy release module according to the rock mass fracture effect to further improve the rock mass fracture effect.

[0065] The energy conduction path optimization model provided in this application is based on the theories of discontinuous rock mechanics, fluid dynamics, and fracture mechanics, and makes the following reasonable assumptions in combination with engineering practice: (1) The target rock mass is a discontinuous medium with natural structural planes, and the attenuation of energy conduction along the structural planes is significantly lower than that of intact rock mass; (2) Phase change energy is mainly transmitted through pressure wave conduction and quasi-static expansion work, and the energy peak value follows an exponential decay law along the propagation path; (3) The outer energy curtain of the multi-layer coupled structure jet nozzle is equivalent to the radial constraint boundary of the main jet, which can reduce the axial energy attenuation of the jet; (4) Rock mass fracture preferentially occurs along the natural structural planes, and the failure mode is mainly tension-shear composite failure. Please refer to the following for the optimization process of energy conduction path optimization model. Figure 5 The method shown.

[0066] Figure 5 This is a flowchart illustrating a phase change fluid-rock mass coupling rock fracturing method according to an embodiment of this application. See also... Figure 5 ,include: S101. Obtain the spatial distribution parameters and mechanical parameters of the rock mass structural planes of the target rock mass.

[0067] In some embodiments, the spatial distribution of rock mass structural surfaces is detected by ground-penetrating radar, the structural details of the rock mass inside the borehole are obtained by borehole camera equipment, and the mechanical properties and stress distribution of the rock mass are inverted by microseismic monitoring equipment; all collected data are input into a data acquisition terminal and integrated to generate a spatial distribution map and mechanical parameters of the rock mass structural surfaces.

[0068] In some embodiments, the input data may also be preprocessed using standardization: The system organizes, converts, and completes the spatial distribution parameters of rock mass structural planes, the mechanical parameters of the target rock mass, and the characteristic parameters of phase change fluids. It also extracts the spatial coordinates, attitude, spacing, aperture, and strength parameters of the rock mass structural planes to generate a structured list, and automatically matches the built-in lithological database to complete missing parameters after importing the lithological parameters.

[0069] In some embodiments, the built-in lithological parameter database can be obtained by calibrating and correcting the model's core parameters such as attenuation coefficient, fracture energy, and reflection coefficient based on indoor experimental data and engineering measured data of common lithologies such as granite, sandstone, shale, and coal seams.

[0070] S102. Based on the spatial distribution parameters and mechanical parameters of the rock mass structure planes of the target rock mass, establish a three-dimensional mesh model of the target rock mass and calculate the global energy impedance matrix of the three-dimensional mesh model.

[0071] In some embodiments, step S102 includes: S1021. Establish a three-dimensional mesh model of the target rock mass.

[0072] Among them, based on the spatial distribution parameters and mechanical parameters of the rock mass structural plane, the spatial coordinates, attitude and mechanical parameters of the rock mass structural plane are automatically identified, and the discontinuous rock mass is transformed into a three-dimensional mesh model with attributes.

[0073] Step S1022: Determine the global energy impedance matrix of the three-dimensional mesh model.

[0074] In step S1022, firstly, attenuation coefficient calculation models are established for the rock mass and rock mass structural surfaces respectively. Then, combined with mechanical parameters, the energy attenuation coefficient of each unit in the three-dimensional mesh model is calculated through the attenuation coefficient calculation model, and the impedance value of each unit is calculated based on the energy attenuation coefficient of each unit in the three-dimensional mesh model to obtain the global energy impedance matrix.

[0075] Specifically, step S1022 includes: Step 1: Calculate the energy attenuation coefficient at each element in the 3D mesh model; where the energy attenuation coefficient of the intact rock mass is determined based on the rock mass strength and density, and the energy attenuation coefficient of the rock mass structural plane is determined based on the structural plane attenuation reduction coefficient and the energy attenuation coefficient of the intact rock mass.

[0076] Step 2: Based on the energy attenuation coefficient and perimeter of each element in the 3D mesh model, determine the impedance value of each element in the 3D mesh model to obtain the global energy impedance matrix of the 3D mesh model.

[0077] In some embodiments, the attenuation coefficient calculation model is as follows: Phase transition energy is transmitted in the rock mass in the form of pressure waves, and the peak pressure along the propagation path follows an exponential decay law:

[0078] In the formula: For the distance of transmission Peak pressure at the location, in MPa; The initial incident pressure is expressed in MPa. Energy decay coefficient, unit is m -1 ; This represents the distance energy travels, measured in meters (m).

[0079] In some examples, the energy decay coefficient Different values ​​are assigned based on the type of conductive medium: For intact rock masses, the attenuation coefficient is denoted as... , The value of is positively correlated with the rock mass strength and density.

[0080] For rock mass structural planes, the attenuation coefficient is denoted as... The calculation formula is:

[0081] In the formula: The attenuation reduction factor of the structural surface ranges from 0.2 to 0.5. It decreases as the opening of the rock mass structural surface increases, reflecting the low impedance conduction characteristics of the structural surface.

[0082] For a confined jet (a main jet radially confined by an energy curtain), the radial diffusion of the main jet within the borehole is suppressed under the radial confinement of the outer energy curtain, and the axial attenuation is further reduced. The axial attenuation coefficient of the confined jet... Calculate using the following formula:

[0083] In the formula: The axial attenuation coefficient of the confined jet, in meters (m). - ¹; The reference axial attenuation coefficient for the unconstrained jet is expressed in meters (m). - ¹; The energy curtain constraint coefficient has a value range of 0.4 to 0.8 and is positively correlated with curtain pressure and flow rate.

[0084] In some embodiments, the energy curtain constraint coefficient The formula for calculation is:

[0085] In the formula: This is the baseline coefficient for the case without a curtain, and its value is 1.0; The working pressure of the energy curtain is expressed in MPa. The working flow rate of the energy curtain is expressed in cubic meters per second (m³). 3 / min.

[0086] Based on the aforementioned energy attenuation coefficient calculation model, the attenuation coefficient of the intact rock mass can be determined. Structural attenuation coefficient Axial attenuation coefficient of confined jet This allows us to calculate the energy attenuation coefficient at each element in the three-dimensional mesh model.

[0087] In some embodiments, after determining the energy attenuation coefficient at each element in the three-dimensional mesh model, the impedance value at each element in the three-dimensional mesh model can be calculated based on the energy attenuation coefficient, thereby obtaining the global energy impedance matrix of the three-dimensional mesh model. The impedance value at each element in the three-dimensional mesh model can be calculated as follows: Impedance = Attenuation Coefficient × Element Side Length.

[0088] S103. Calculate the fracturing energy of the rock mass structural planes. Using the fracturing energy of the rock mass structural planes as an indicator, determine several rock mass structural planes as candidate structural planes.

[0089] In step S103, the critical fracture energy of all rock mass structural surfaces is calculated one by one, and key structural surfaces with low fracture energy and controlling effect on the overall integrity of the rock mass are selected as candidate structural surfaces (also candidate energy release targets).

[0090] In some embodiments, the selection priority of candidate structural planes is as follows, from high to low: joint intersections > dense fracture zones > principal bedding planes > isolated joints.

[0091] In some embodiments, the calculation process for the fracture energy of rock mass structural planes is as follows: Step 1: Determine the tensile fracturing energy per unit area of ​​the rock mass structural plane based on the fracture toughness and elastic modulus of the rock mass.

[0092] Step 2: Determine the total critical tensile fracturing energy of the rock mass structural plane based on the effective working area of ​​the rock mass structural plane and the tensile fracturing energy per unit area of ​​the rock mass structural plane.

[0093] Step 3: Determine the shear strength of the rock mass structural surface based on the cohesion of the rock mass structural surface, the normal stress of the rock mass structural surface, and the internal friction angle of the rock mass structural surface.

[0094] Step 4: Determine the shear fracture energy per unit area of ​​the rock mass structural surface based on the shear strength of the rock mass structural surface and the boundary shear displacement of the rock mass structural surface.

[0095] Step 5: Determine the total critical shear fracture energy of the rock mass structural surface based on the shear fracture energy per unit area and the effective working area of ​​the rock mass structural surface.

[0096] Step 6: Determine the fracture energy of the rock mass structural plane based on the total critical tensile fracture energy and the total critical shear fracture energy of the rock mass structural plane.

[0097] Specifically, the calculation process for the critical fracture energy of the rock mass structural plane is as follows: First, the minimum energy threshold required for each structural plane to break is quantified, serving as the basis for target screening and path effectiveness verification.

[0098] Regarding the tensile fracture threshold, based on fracture mechanics theory, the tensile fracture energy per unit area of ​​the structural surface is... Calculate using the following formula:

[0099] In the formula: Tensile fracturing energy per unit area of ​​structural surface, in J / m 2 ; Fracture toughness of the structural plane, in MPa m^0.5; This represents the elastic modulus of the rock mass, expressed in GPa.

[0100] Total critical tensile fracture energy of a single target structural surface for:

[0101] In the formula: The tensile fracture energy at the structural boundary is expressed in J. The effective working area of ​​the rock mass structural plane, in m². 2 .

[0102] For the shear fracture threshold, based on the Mohr-Coulomb strength criterion, the shear strength of the structural surface is calculated using the following formula:

[0103] In the formula: The shear strength of the structural surface is expressed in MPa. The cohesion of the structural surface is expressed in MPa. This represents the normal geostress of the structural surface, expressed in MPa. The internal friction angle of the structural surface is expressed in degrees (°).

[0104] Shear fracture energy per unit area of ​​structural surface Calculate using the following formula:

[0105] In the formula: Shear fracture energy per unit area of ​​the structural surface, in J / m 2 ; This represents the shear displacement at the structural boundary, expressed in meters (m).

[0106] The total critical shear fracture energy of a single target structural plane is .

[0107] The critical fracture energy of this structural surface is determined by taking the smaller value between the tensile fracture threshold and the shear fracture threshold. This indicates that the rock mass preferentially fails along the direction of least resistance.

[0108] S104. Determine the preset nozzle position, and in combination with the physical property parameters of the phase change fluid, use optimization algorithms to determine the path with the minimum total energy attenuation from the preset nozzle position to several candidate structural surfaces, obtain a set of candidate paths, and determine the connectivity of several candidate paths in the set of candidate paths through fluid-structure interaction analysis, and obtain the target path.

[0109] In step S104, after importing the characteristic parameters of the phase change fluid, the phase change expansion energy and jet kinetic energy per unit volume of the phase change fluid are calculated based on the characteristic parameters of the phase change fluid for subsequent analysis and calculation.

[0110] In step S104, a three-dimensional optimization algorithm is used to determine the path with the minimum total energy attenuation from the preset nozzle position to several candidate structural surfaces as candidate paths. Each candidate structural surface corresponds to a candidate path, thereby forming a set of candidate paths.

[0111] In some embodiments, the three-dimensional optimization algorithm determines candidate paths from a preset nozzle position to the target structural surface with the goal of maximizing energy utilization.

[0112] In some embodiments, the objective function used by the three-dimensional optimization algorithm is:

[0113] In the formula: Energy efficiency; For the first The effective energy at the energy release target point is expressed in kJ. The total energy injected into the phase change fluid, expressed in kJ.

[0114] In some embodiments, the total energy injected by the phase change fluid The calculation formula is as follows:

[0115] In the formula: To inject pressure, For injection rate, For injection time.

[0116] After obtaining the set of paths with the minimum total energy attenuation through a three-dimensional optimization algorithm, the crack propagation process is simulated using a fluid-structure interaction solver to verify the connectivity of the paths, ensure that the crack penetration rate meets the constraint requirements, and finally determine the optimal energy conduction path.

[0117] In some embodiments, the three-dimensional optimization algorithm can be a particle swarm optimization algorithm, a genetic algorithm, etc.

[0118] After obtaining the candidate path set, the connectivity of several candidate paths in the set is determined through fluid-structure interaction (FSI) analysis. The governing equations used in the FSI analysis are as follows: Fluid-structure interaction analysis, based on the effective stress principle, achieves bidirectional coupling between the fluid pressure field and the rock mass stress field, using the effective stress tensor. Calculate using the following formula:

[0119] In the formula: For effective stress tensor; This represents the total stress tensor of the rock mass. The Kronecker function; This represents the pore fluid pressure, expressed in MPa.

[0120] The elastic constitutive relation of the rock mass satisfies: In the formula: Let be the rock mass elastic stiffness tensor. From the elastic modulus of rock mass Compared with Poisson Sure; This represents the rock mass strain tensor.

[0121] When the fluid pressure reduces the effective normal stress of the structural surface to the tensile strength, the structural surface cracks, the energy conduction channel expands, and the attenuation coefficient decreases simultaneously, forming a positive feedback mechanism of "energy conduction - crack expansion - attenuation reduction". The energy conduction path optimization model simulates the continuous expansion and evolution of the crack by iteratively solving this process.

[0122] S105. Control the phase change fluid to be delivered along the target path to the target area of ​​the target rock mass, and break the target rock mass.

[0123] Drilling and equipment deployment are carried out according to the target path determined in S104. The drilling diameter is controlled between 50mm and 150mm, the drilling depth is between 5m and 50m, and the drilling angle is determined according to the spatial orientation of the target structural surface to ensure that the drilling can cover the target area.

[0124] After drilling is completed, high-pressure air is used to clean the rock powder and impurities inside the borehole to prevent blockage of pipelines and nozzles. Then, the injection string, multi-layer coupled jet nozzle, and in-hole energy collector are installed in the borehole in sequence according to the optimized plan. The placement position and guide vane angle of the in-hole energy collector are precisely adjusted to ensure that its reflection chamber and guide direction are aligned with the target structural surface. After the equipment is deployed, the entire system is tested for sealing and linkage to ensure that all components are working properly.

[0125] Drilling and equipment deployment parameters are matched in reverse: Based on the spatial distribution of the target path, the coordinate position, depth and inclination of the borehole are optimized to ensure that the borehole is deployed along the main conduction path; at the same time, the placement position of the energy collector in each borehole, the angle of the guide vanes, and the structural parameters of the matched multi-layer coupling jet nozzle are accurately calculated.

[0126] Injection process parameter optimization calculation: Combining the total energy attenuation of the optimal path and the critical fracture energy of the target point, the required initial injection pressure and injection rate are calculated in reverse; Based on lithological characteristics and engineering requirements, the injection method, pulse frequency and injection sequence are optimized and determined; The matching energy curtain pressure and flow rate are calculated simultaneously to ensure the optimal first-level constraint conduction effect.

[0127] Multi-objective verification and result output: Verify all conditions such as energy utilization rate, fracture effect, equipment parameters, and construction constraints. If not met, iteratively adjust the number of target points, drilling location, and process parameters until all constraints are met. Finally, output a complete set of design results, including the coordinates of the core energy release target points, the three-dimensional distribution of the optimal energy conduction path, drilling construction parameters, nozzle working parameters, collector placement and flow guidance parameters, and phase change fluid injection parameters, providing a complete design basis for subsequent construction.

[0128] The multi-stage energy coupling loading startup system performs energy transfer and release operations, realizing multi-stage energy coupling loading in two phases: (1) First-stage pressurization and constraint conduction: The phase change fluid supply and pressurization unit is started to extract the phase change fluid from the insulated storage tank. After being filtered, the fluid is pressurized to the set pressure (10-200MPa) calculated by the model through a high-pressure plunger booster pump, and then delivered to the multi-layer coupled structure jet nozzle through the injection tubing. The inner flow channel injects the phase change fluid into the borehole in the form of a high-speed jet of 100-300m / s; at the same time, the outer annular flow channel injects high-pressure medium synchronously to form an energy curtain that surrounds the main jet. The flow rate of the high-pressure medium is 0.05-0.5m³ / s. 3 / min, pressure of 5-15MPa. By radially confining the main jet through the energy curtain, the energy dissipation at the orifice of the jet is greatly reduced, achieving efficient confined energy transfer to the depth of the borehole and ensuring stable energy transfer to the energy collector inside the borehole; (2) Secondary pressurization and directional focusing release: When the high-energy fluid jet arrives at the energy collector in the borehole, the collector is activated by the pressure or temperature of the jet, and the borehole section is quickly sealed. The jet energy flow enters the reflection chamber of the collector, where it undergoes multiple reflections and superpositions to achieve a multiplication effect of the pressure wave and complete the secondary pressurization of energy. Subsequently, the high-energy fluid after secondary pressurization is directionally focused onto the pre-identified key structural surface of the rock mass by the pre-adjusted guide vanes, achieving precise directional release of energy and driving the rock mass to undergo tensile or shear fracture along the structural surface, forming initial fractures.

[0129] S106. Collect rock mass fracture data, fracture propagation data, and borehole pressure change data of the target rock mass, and adjust the parameters used by the energy release module based on the rock mass fracture data, fracture propagation data, and borehole pressure change data.

[0130] In some embodiments, monitoring devices such as acoustic emission sensors, strain gauges, and borehole pressure sensors are used to collect real-time data on rock mass fracture, fracture propagation, and borehole pressure changes. The monitoring data is then fed back to the intelligent control and process matching unit in real time via a data communication module.

[0131] The PLC industrial controller analyzes the feedback data in real time to determine the energy release effect and the crack expansion status. If it detects that the energy release deviates from the optimal path, the crack expansion is insufficient or excessively broken, it will finely adjust the injection pressure, injection rate, and injection sequence of the phase change fluid, as well as the pressure of the energy curtain and the angle of the guide vanes of the agglomerator in real time.

[0132] The parameter deviation of the fine-tuning does not exceed ±10% of the optimal parameter, ensuring that energy is always released along the optimal path, and finally forming a well-connected and evenly distributed network or sheet-like fracture system in the target rock mass. The fracture spacing is controlled at 0.1-0.5m, and the fracture penetration rate is ≥80%, thus completing the efficient crushing of the rock mass.

[0133] In some embodiments, the process of adjusting the parameters used by the energy release module based on rock mass fracture data, fracture propagation data, and borehole pressure distribution data includes: Step 1: Calculate the fracture propagation rate and fracture propagation degree based on the fracture propagation data.

[0134] Step 2: Calculate the deviation rate of the energy release path based on the pressure distribution data inside the hole.

[0135] Step 3: Calculate the energy release efficiency based on rock mass fracture data.

[0136] Step 4: Adjust the parameters used by the energy release module based on the fracture propagation rate and fracture propagation degree, the deviation rate of the energy release path, and the energy release efficiency.

[0137] The specific process for determining the fracture propagation rate and fracture propagation degree based on fracture propagation data is as follows: Step 1: Calculate the fracture propagation rate based on the fracture propagation length. The specific process is as follows:

[0138] In the formula: The crack propagation length per unit time (in meters). The data acquisition time interval (in seconds).

[0139] The second step is to calculate the fracture propagation based on acoustic emission counting. The specific process is as follows:

[0140] In the formula: The count of acoustic emissions per unit time. The optimal acoustic emission count threshold is calculated for the model.

[0141] In some embodiments, when 0.3≤ ≤0.8 and When ∈ [0.01 mm / s, 0.1 mm / s], the crack propagation state is reasonable; when <0.3 or <0.01mm / s, is judged as insufficient crack propagation; when >0.8 or >0.1 mm / s indicates excessive rock mass fracturing.

[0142] In some embodiments, the pressure distribution data inside the orifice determines the deviation of the energy release path, specifically as follows: The first step is to calculate the actual pressure gradient based on the pressure distribution data inside the orifice. The specific process is as follows:

[0143] In the formula: For drilling different depths Pressure inside the hole (MPa). For drilling different depths The pressure inside the hole (MPa).

[0144] Step 2: Based on the optimal pressure gradient Determine the deviation rate of the energy release path. The specific process is as follows:

[0145] In some embodiments, when If the deviation is greater than 10%, it is determined that the energy release has deviated from the optimal path and parameter fine-tuning is required.

[0146] In some embodiments, the process of determining energy release efficiency is as follows: Calculate energy utilization rate Combining the energy injected by the phase change fluid with the energy absorbed by the rock mass, the formula is as follows:

[0147] In the formula: Energy (KJ) absorbed by the rock mass. Energy (KJ) is injected into the phase change fluid.

[0148] In some embodiments, the process of calculating the energy absorbed by the rock mass based on rock mass fracture data (such as rock mass strain) is as follows:

[0149] In the formula: The bulk modulus of the rock mass. For the rock mass strain increment, The target rock mass volume.

[0150] In some embodiments, the calculation process for the phase change fluid injection energy is as follows:

[0151] In the formula: To inject pressure, For injection rate, For injection time.

[0152] In some embodiments, the judgment criterion is when If the energy dissipation is less than 60%, it is determined that the energy curtain pressure or jet parameters need to be adjusted.

[0153] After the operation is completed, shut down the phase change fluid supply and pressurization unit, stop fluid injection, and wait for the pressure inside the borehole to drop to atmospheric pressure. Then, recover the energy collector, jet nozzle and injection string inside the borehole, clean the borehole, and complete the entire operation process.

[0154] See Figure 6 The diagram shows a comparison of the rock fracture network formed by traditional phase transformation fracturing technology and the method of this invention. It can be seen that the method of this application has a better rock fracture effect.

[0155] Example 1: Application in pre-fracture of granite hard rock ore bodies This embodiment addresses the pre-fracture scenario of granite hard rock ore bodies (compressive strength 100-150 MPa, Poisson's ratio 0.2-0.3, elastic modulus 30-40 GPa). In this scenario, the rock mass has high strength and good integrity. Traditional phase transformation fracturing technology has low energy utilization and poor fracturing effect. The system and method of this invention are adopted, and the specific steps are as follows: 1. Rock Mass Diagnosis and Path Planning: Utilizing rock mass structural plane identification and mechanical analysis units, the distribution of shallow and intermediate structural planes in the ore body is detected by ground-penetrating radar. Details of joints and fractures within the borehole are obtained using borehole camera equipment. The mechanical properties of the rock mass are inverted using microseismic monitoring equipment to acquire detailed geological data for the target area. This ore body exhibits two sets of dominant joint surfaces, with joint spacing of 0.5-1m, tensile strength of 10-15MPa, and shear strength of 30-40MPa. The data was input into the energy conduction path optimization model, which was matched with the "high-stress hard rock mode". The main energy release target point was determined to be the intersection of two sets of dominant joint surfaces. The optimal energy conduction path was perpendicular to the joint surface. The optimal process parameters were calculated as follows: nozzle diameter 6 mm, nozzle pressure 120 MPa, collector placement position 0.5 m away from the joint surface, collector guide vane angle 45°, liquid nitrogen injection rate 0.3 m³ / min, pulse injection with a pulse frequency of 3 Hz, and compressed air for the outer energy curtain at a pressure of 10 MPa and a flow rate of 0.2 m³ / min.

[0156] 2. Drilling and Equipment Layout: Drilling will be carried out according to the plan, with a diameter of 100mm, a depth of 15m, and an angle of 30° between the borehole and the joint surface. After drilling is completed, the rock powder inside the borehole will be cleaned. The injection tubing, multi-layer coupled jet nozzle (inner flow channel inlet diameter 6mm, outer annular flow channel width 2mm, cavity length ratio 0.75, cavity diameter ratio 2.6), and in-hole energy concentrator (reflection chamber is cylindrical, inner diameter 30mm, with 4 guide vanes) will be installed in the borehole according to the optimized plan. The angle of the concentrator will be adjusted to ensure that the guide vanes are aligned with the joint surface intersection, and the equipment will be debugged.

[0157] 3. Multi-stage energy coupling loading: The phase change fluid supply and pressurization unit is activated, using liquid nitrogen as the phase change fluid. The liquid nitrogen is extracted and pressurized to 120 MPa, and then delivered to the jet nozzle through the injection string. The inner flow channel injects liquid nitrogen into the borehole at a high speed of 200 m / s, while the outer annular flow channel simultaneously injects compressed air to form an energy curtain, constraining jet diffusion and achieving primary energy conduction. After the liquid nitrogen jet reaches the energy collector in the borehole, it triggers the collector to activate (trigger pressure 20 MPa, trigger temperature -30℃). The pressure wave is reflected and superimposed in the reflection chamber, and the pressure is pressurized a second time to 250 MPa. Through 45° guide vanes, the energy flow is directed and focused to the joint surface intersection, achieving secondary energy release and driving joint surface expansion.

[0158] 4. Dynamic Feedback and Adjustment: During construction, acoustic emission monitoring equipment was used to collect rock fracture signals in real time, and the data was fed back to the intelligent control unit. Monitoring revealed that some energy initially deviated from the target joint surface. The controller then fine-tuned the angle of the aggregator's guide vanes to 48° and the liquid nitrogen injection pressure to 125 MPa in real time to ensure energy focusing. After 30 minutes of continuous operation, injection was stopped, and the equipment was retrieved after the borehole pressure dropped to atmospheric pressure.

[0159] Effect Verification: After adopting the method of this invention, the granite ore body formed a well-connected network of fractures with a fracture spacing of 0.2-0.4m and a fracture penetration rate of 85%. The broken pieces were of uniform size, with the largest piece not exceeding 50cm, facilitating subsequent loading operations. Compared with traditional liquid nitrogen fracturing technology, when fracturing the same volume (100m³) of rock mass, the liquid nitrogen consumption decreased from 20m³ to 12m³, a reduction of 40%; the energy efficiency increased from 28% to 72%, an increase of 2.6 times; and the pre-splitting efficiency increased from 5m³ / h to 12m³ / h, an increase of 1.4 times. Moreover, there was no significant vibration during the fracturing process, no damage to the surrounding rock, and significantly improved safety.

[0160] Example 2: Volumetric Stimulation of Shale Gas Reservoirs This embodiment addresses the volumetric fracturing scenario of low-permeability shale gas reservoirs (permeability ≤ 0.1 mD, compressive strength 60-80 MPa, Poisson's ratio 0.25-0.35, elastic modulus 20-30 GPa). In this scenario, the rock mass has low permeability, traditional hydraulic fracturing consumes a large amount of water and is prone to water-locking effects, and existing phase transformation fracturing techniques are difficult to form complex fracture networks. The system and method of this invention are adopted, and the specific steps are as follows: 1. Rock Mass Diagnosis and Path Planning: Utilizing the rock mass structure plane identification and mechanical analysis unit, and employing ground-penetrating radar and microseismic monitoring equipment, a natural fracture network of the reservoir was mapped to obtain the degree of fracture development, distribution orientation, and mechanical parameters of the shale reservoir. This reservoir exhibits dense natural fractures with a spacing of 0.1-0.3 m, tensile strength of 8-12 MPa, and shear strength of 20-30 MPa. The data was input into an energy conduction path optimization model, which was matched to a "low-permeability shale multi-cluster model." Five energy release target points were designed, and the pathways connecting the main fracture and natural fractures were planned. The optimal process parameters were calculated as follows: nozzle diameter 4 mm, nozzle pressure 80 MPa, multiple collectors distributed according to fractures with a spacing of 2 m, guide vane angle adjustable from 35° to 55°, liquid CO2 injection rate 0.5 m³ / min, continuous injection mode, and an outer energy curtain using clean water at a pressure of 8 MPa and a flow rate of 0.3 m³ / min.

[0161] 2. Drilling and Equipment Deployment: Drilling will be carried out according to the plan, with a diameter of 80mm and a depth of 30m. The drilling direction will be parallel to the natural fracture. After drilling is completed, the rock powder inside the borehole will be removed. A multi-layered coupled jet nozzle (inner flow channel inlet diameter 4mm, outer annular flow channel width 1mm, cavity length ratio 0.7, cavity diameter ratio 2.5) and five in-hole energy concentrators (spherical reflection chambers with an inner diameter of 25mm and three guide vanes) will be deployed in the borehole at the optimized positions via coiled tubing. The angle of the guide vanes of each concentrator will be adjusted to ensure alignment with the target fracture. Equipment commissioning will then be completed.

[0162] 3. Multi-stage energy coupling loading: The phase change fluid supply and pressurization unit is activated, using liquid CO2 as both the phase change fluid and fracturing fluid. The liquid CO2 is extracted and pressurized to 80 MPa, then transported to the jet nozzle through coiled tubing. The inner flow channel injects the liquid CO2 into the borehole at a high speed of 250 m / s, while the outer annular flow channel simultaneously injects clean water to form an energy curtain, constraining jet diffusion and achieving primary energy conduction. After the liquid CO2 jet reaches the energy collectors in each borehole, it is sequentially activated (trigger pressure 18 MPa, trigger temperature -20℃). The pressure wave is reflected and superimposed in the reflection chamber, resulting in a secondary pressurization to 160 MPa (the peak pressure after phase change can reach 185 MPa). Through adjustable-angle guide vanes, the energy flow is directionally released to each target fracture, opening fractures at multiple locations. The adsorption and replacement effect of CO2 with shale promotes fracture propagation.

[0163] 4. Dynamic Feedback and Adjustment: During construction, strain gauges and microseismic monitoring equipment are used to collect real-time signals of rock fracture propagation and borehole pressure changes, feeding the data back to the intelligent control unit. Monitoring revealed insufficient fracture propagation in some areas. The controller fine-tuned the liquid CO2 injection rate to 0.6 m³ / min and adjusted the guide vane angle of the corresponding collector to 50° to increase energy release intensity. For areas with excessive fracture propagation, the injection rate was fine-tuned to 0.4 m³ / min to reduce energy release intensity. After 60 minutes of continuous operation, injection was stopped, and the equipment was retrieved after the borehole pressure dropped to atmospheric pressure.

[0164] Effect Verification: After adopting the method of this invention, a complex network of fractures was formed in the shale gas reservoir, with fracture spacing of 0.1-0.3m, fracture penetration rate of 88%, and fracture surface area increased by 60% compared with traditional hydraulic fracturing; no large amount of water is required, and the water consumption per cubic meter of reservoir stimulation is reduced from 15m³ to 0, avoiding the water-locking effect, and the shale gas recovery rate is increased from 18% to 35%, an increase of 1.9 times; compared with the existing liquid CO2 phase change fracturing technology, the energy effective utilization rate is increased from 32% to 75%, an increase of 2.3 times, and no toxic or harmful gases are generated during the stimulation process, which is environmentally friendly and realizes the green and efficient development of shale gas reservoirs.

[0165] Example 3: Roof cutting and pressure relief applied to hard roofs in coal mines This embodiment addresses the scenario of roof cutting and pressure relief in coal mines with hard, thick sandstone roofs (compressive strength 90-110 MPa, Poisson's ratio 0.22-0.28, elastic modulus 28-35 GPa). In this scenario, the roof has high strength and poor self-collapse capability, making traditional blasting roof cutting risky and existing phase transformation fracturing techniques ineffective. The system and method of this invention are adopted, and the specific steps are as follows: 1. Rock Mass Diagnosis and Path Planning: Utilizing the rock mass structure plane identification and mechanical analysis unit, and through ground-penetrating radar and borehole camera equipment, the bedding distribution, fracture development, and mechanical parameters of the roof were identified. The bedding spacing of the roof is 0.8-1.2m, the tensile strength is 9-14MPa, and the shear strength is 28-38MPa. The data was input into the energy conduction path optimization model, which was matched to the "hard roof cutting mode." The energy release target point was determined to be the roof bedding plane, and the optimal energy conduction path was perpendicular to the roof bedding direction. The optimal process parameters were calculated as follows: nozzle diameter 7mm, nozzle pressure 100MPa, collector placement position 0.6m from the roof bedding plane, guide vane angle 40°, liquid CO2 injection rate 0.4m³ / min, pulsed injection, pulse frequency 2Hz, and compressed air for the outer energy curtain at a pressure of 12MPa and a flow rate of 0.25m³ / min.

[0166] 2. Drilling and Equipment Layout: Drilling will be carried out in the roadway sidewalls according to the plan. The borehole diameter is 120mm, the drilling depth is 20m, the roof cutting height is 8m, and the angle between the borehole and the roof bedding plane is 30°. After the drilling is completed, the rock powder inside the borehole will be cleaned. The injection tubing, multi-layer coupled jet nozzle (inner flow channel inlet diameter 7mm, outer annular flow channel width 2.5mm, cavity length ratio 0.78, cavity diameter ratio 2.7), and in-hole energy collector (reflection chamber is cylindrical, inner diameter 40mm, with 5 guide vanes) will be installed in the borehole. The angle of the collector will be adjusted to ensure that the guide vanes are aligned with the roof bedding plane, and the equipment will be debugged.

[0167] 3. Multi-stage energy coupling loading: The phase change fluid supply and pressurization unit is activated, using liquid CO2 as the phase change fluid. The liquid CO2 is extracted and pressurized to 100MPa, and then delivered to the jet nozzle through the injection string. The inner flow channel injects the liquid CO2 into the borehole at a high speed of 180m / s, while the outer annular flow channel simultaneously injects compressed air to form an energy curtain, achieving primary energy conduction. After the liquid CO2 jet reaches the energy collector in the borehole, it triggers the collector to activate (trigger pressure 25MPa, trigger temperature -25℃). The pressure wave is reflected and superimposed in the reflection chamber, and the pressure is pressurized a second time to 220MPa (the peak pressure after phase change can reach over 185MPa). Through 40° guide vanes, the energy flow is directionally focused onto the top plate bedding plane, achieving secondary energy release and driving the expansion of the top plate bedding plane to form continuous directional fracture grooves.

[0168] 4. Dynamic Feedback and Adjustment: During construction, microseismic monitoring equipment and roof displacement monitoring equipment were used to collect roof fracture signals and displacement data in real time, and the data was fed back to the intelligent control unit. Monitoring revealed that the initial roof displacement growth was slow. The controller fine-tuned the liquid CO2 injection pressure to 105 MPa in real time and adjusted the angle of the aggregator guide vanes to 42° to accelerate fracture propagation. After 40 minutes of continuous operation, injection was stopped, and the equipment was retrieved after the drilling pressure dropped to atmospheric pressure.

[0169] Effect Verification: After adopting the method of this invention, a continuous directional fracture groove was formed in the roof, with a fracture penetration rate of 90%, effectively disrupting the stress transmission path of the roof. The roof in the goaf could collapse in time, and the overhanging area was reduced by 80%. Monitoring data showed that the convergence of the roof and floor decreased by 23.5%, the deformation of the sidewalls decreased by 29.2%, the peak support pressure decreased by 22.3%, and the maintenance cycle of the roadway was extended by 42%. Compared with traditional explosive blasting for roof cutting, safety is significantly improved, and there is no need for cumbersome explosive approval and management procedures. Compared with the existing liquid CO2 phase change fracturing roof cutting technology, the roof cutting efficiency is increased by 65%, and the effective energy utilization rate is increased from 30% to 73%, an increase of 2.4 times. This effectively solves the problem of roof cutting and pressure relief in hard roofs and reduces the risk of disasters such as rock bursts and sudden roof collapse.

[0170] Figure 7 This is a structural block diagram of an electronic device provided according to an embodiment of this application. See also... Figure 7 Electronic devices may include Figure 6 The rock mass fracturing system based on phase change fluid-rock mass coupling is described above. Typically, the electronic device 50 includes a processor 51 and a memory 52.

[0171] Processor 51 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. Processor 51 may be implemented using at least one hardware form selected from DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). Processor 51 may also include a main processor and a coprocessor. The main processor is used to process data in the wake-up state, also known as a CPU (Central Processing Unit); the coprocessor is a low-power processor used to process data in the standby state. Memory 52 may include one or more computer-readable storage media, which may be non-transitory. Memory 52 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In some embodiments, the non-transitory computer-readable storage media in memory 52 is used to store at least one instruction, which is executed by processor 51 to implement the rock fracturing method based on phase change fluid-rock mass coupling provided by the method embodiments of this application, executed by an electronic device.

[0172] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rock mass breaking system based on phase change fluid-rock mass coupling, characterized in that, include: Phase change fluid supply module, used to supply phase change fluid; The rock mass structure analysis module is used to obtain the spatial distribution parameters and mechanical parameters of the rock mass structure planes of the target rock mass. The energy release module includes an in-orifice energy collector and a multi-layer coupled jet nozzle. The in-orifice energy collector is used to pressurize the phase change fluid and set the phase change fluid in a predetermined direction. The multi-layer coupled jet nozzle is used to eject the pressurized phase change fluid in a predetermined direction. And a process matching unit, used to determine the process parameters to be used by the energy release module based on the characteristic parameters of the phase change fluid, the spatial distribution parameters of the natural structural surfaces of the target rock mass, and the physical and mechanical parameters.

2. The rock mass fragmentation system based on phase change fluid-rock mass coupling of claim 1, wherein, The multi-layer coupled jet nozzle includes: The inner flow channel and the outer annular flow channel surrounding the inner flow channel; the inner flow channel is used to transport phase change fluid to form the main jet, and the outer annular flow channel is used to transport high-pressure medium to form an energy curtain that surrounds the main jet.

3. The rock mass fragmentation system based on phase change fluid-rock mass coupling of claim 1, wherein, The in-orifice energy concentrator includes: The reflective chamber and the guide vanes; the reflective chamber pressurizes the phase change fluid based on the pressure wave multiplication effect; the guide vanes are used to direct and focus the pressurized main jet to the target area.

4. A rock mass breaking method based on phase change fluid-rock mass coupling, characterized in that, The rock mass fracturing system based on phase change fluid-rock mass coupling as described in any one of claims 1 to 3 includes: Obtain the characteristic parameters of the phase change fluid, the spatial distribution parameters and mechanical parameters of the rock mass structure plane of the target rock mass; Based on the spatial distribution parameters and mechanical parameters of the rock mass structure planes of the target rock mass, a three-dimensional mesh model of the target rock mass is established, and the global energy impedance matrix of the three-dimensional mesh model is calculated. Calculate the fracturing energy of rock mass structural planes, and use the fracturing energy of rock mass structural planes as an indicator to determine several rock mass structural planes as candidate structural planes; The preset nozzle position is determined, and combined with the physical property parameters of the phase change fluid, the optimization algorithm is used to determine the path with the minimum total energy attenuation from the preset nozzle position to several candidate structural surfaces, and a set of candidate paths is obtained. Then, through fluid-structure interaction analysis, the connectivity of several candidate paths in the set of candidate paths is determined, and the target path is obtained. The phase change fluid is controlled to be delivered along the target path to the target area of ​​the target rock mass, thereby breaking up the target rock mass; Data on rock mass fracture, fracture propagation, and borehole pressure changes are collected from the target rock mass. The parameters used by the energy release module are adjusted based on the rock mass fracture data, fracture propagation data, and borehole pressure distribution data.

5. The phase change fluid - rock mass coupled based rock mass fragmentation system according to claim 1, characterized in that, The calculation process for the global energy impedance matrix of the 3D mesh model is as follows: Calculate the energy attenuation coefficient at each element in the three-dimensional mesh model; where the energy attenuation coefficient of the intact rock mass is determined based on the rock mass strength and density, and the energy attenuation coefficient of the rock mass structural plane is determined based on the structural plane attenuation reduction coefficient and the energy attenuation coefficient of the intact rock mass; Based on the energy attenuation coefficient and perimeter of each element in the 3D mesh model, the impedance value of each element in the 3D mesh model is determined, and the global energy impedance matrix of the 3D mesh model is obtained.

6. The method according to claim 4, wherein, The calculation process for the fracture energy of the rock mass structural plane is as follows: Based on the fracture toughness and elastic modulus of the rock mass structural plane, determine the tensile fracturing energy per unit area of ​​the rock mass structural plane. The total critical tensile fracturing energy of the rock mass structural plane is determined based on the effective working area of ​​the rock mass structural plane and the tensile fracturing energy per unit area of ​​the rock mass structural plane. The shear strength of the rock mass structural surface is determined based on the cohesion of the rock mass structural surface, the normal stress of the rock mass structural surface, and the internal friction angle of the rock mass structural surface. Based on the shear strength of the rock mass structural surface and the boundary shear displacement of the rock mass structural surface, determine the shear fracture energy per unit area of ​​the rock mass structural surface; The total critical shear fracture energy of the rock mass structural surface is determined based on the shear fracture energy per unit area of ​​the rock mass structural surface and the effective working area of ​​the rock mass structural surface. The fracture energy of the rock mass structural plane is determined based on the total critical tensile fracture energy and the total critical shear fracture energy of the rock mass structural plane.

7. The method according to claim 4, wherein, The objective function used in the optimization algorithm is: In some embodiments, the objective function used by the three-dimensional optimization algorithm is: In the formula: Energy efficiency; For the first Effective interaction energy at each candidate structural surface; Inject total energy into the phase change fluid.

8. The rock mass fracturing method based on phase change fluid-rock mass coupling according to claim 4, characterized in that, The process of adjusting the parameters used in the energy release module based on rock mass fracture data, fracture propagation data, and borehole pressure distribution data includes: The fracture propagation rate and fracture propagation degree are calculated based on the fracture propagation data. The deviation rate of the energy release path was calculated based on the pressure distribution data inside the borehole; Energy release efficiency was calculated based on rock mass fracture data; The parameters used in the energy release module are adjusted based on the fracture propagation rate and fracture propagation extent, the deviation rate of the energy release path, and the energy release efficiency.

9. An electronic device, characterized in that, Including the rock mass fracturing system based on phase change fluid-rock mass coupling as described in any one of claims 1 to 3.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one piece of program code, which is executed by a processor to implement the rock mass fracturing method based on phase change fluid-rock mass coupling as described in any one of claims 4 to 8.

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