Underground CO2 pre-fracturing sand injection for enhanced permeability, CCUS equipment and methods

Abstract

This invention provides a pre-fracturing and permeability enhancement device and method for carbon dioxide capture, utilization, and storage (CCUS) in underground mines. Belonging to the field of energy and mining engineering technology, the device includes a high-pressure pumping system, a high-pressure sand injection system, an array-type acoustic monitoring system, a gas liquefaction and separation system, and a central monitoring system. The high-pressure pumping system includes a high-pressure fluid storage system and a pumping monitoring system. The method involves connecting each device after drilling. The monitoring system controls the pumping of high-pressure water, high-pressure acid gas, or a solid-liquid-gas multiphase fluid. Combined with array-type acoustic monitoring, the morphology of rock fractures is regulated. After fracturing, CO2 is recovered, and the carbon sequestration, capture, and utilization rates are analyzed. This invention integrates fracturing permeability enhancement with carbon capture, utilization, and storage, improving operational efficiency and safety. This device and method can be extended to the surface, contributing to the achievement of dual-carbon goals in the energy sector and the green development of deep resources.

Description

Technical Field

[0001] This invention relates to the field of energy and mining engineering technology, specifically to a carbon dioxide pre-fracturing sand injection and permeability enhancement device and method for underground mines. Background Technology

[0002] With the advancement of deep resource development, formation permeability enhancement technology has become a core support for overcoming engineering bottlenecks. The low porosity and low permeability characteristics of deep formations directly restrict the efficiency and safety of resource extraction, giving rise to a technology system centered on formation weakening. In the coal mining sector, high-gas, low-permeability coal seams have low gas extraction rates and are prone to accidents. The fracture network constructed by formation weakening can significantly improve extraction efficiency and is key to safe mining. In unconventional oil and gas extraction, shale gas and other reservoirs are tight, and formation permeability enhancement is a prerequisite for commercial mining. Weakening technologies such as hydraulic fracturing have become standard practice. In tunneling engineering, tunneling efficiency is low in hard rock formations. Pre-tunneling formation weakening treatment can significantly increase speed and shorten the construction period. High-strength roof weakening technology achieves controllable weakening by changing the mechanical properties of the roof, taking into account both support safety and resource recovery. Meanwhile, under the goal of "carbon neutrality," carbon capture, utilization, and storage (CCUS) technology has become a core direction for carbon reduction. The geological space of low-permeability coal and rock strata provides natural conditions for CO2 sequestration. Injecting CO2 into coal and rock strata to achieve integrated "permeability enhancement and carbon sequestration" has become an important path for the green transformation of industries such as coal. However, the integration of current coal and rock strata permeability enhancement technology and CCUS technology still faces many bottlenecks, making it difficult to balance permeability enhancement efficiency and carbon sequestration effect, and failing to meet the needs of safe, efficient, and green mining.

[0003] Existing technologies have several significant shortcomings. While traditional hydraulic equipment is simple and low-cost, it consumes a large amount of water, creating a significant contradiction with the water scarcity in mining areas. Furthermore, it easily triggers hydration and expansion of the coal and rock mass, leading to fracture closure, and the wastewater causes environmental pollution. CO2 fracturing, although offering advantages such as high rock-breaking efficiency and no wastewater discharge, lacks an effective fracture support mechanism. Fractures are prone to closure after depressurization, and the synergistic control technology of CO2, water, and proppant is immature. The precision of multiphase flow mixing and parameter control is insufficient, and the matching between CO2 injection parameters and coal seam fracture expansion during fracturing is poor, lacking real-time monitoring and adjustment methods. While proppant-assisted fracturing can maintain fracture conductivity, traditional systems are poorly compatible with CO2 fracturing. Insufficient proppant suspension easily leads to sand blockage, and the sand ratio adjustment lacks precise control. In terms of CCUS technology, CO2 capture and injection are disconnected, exhaust gas absorption and separation efficiency is low, there is a lack of full-process monitoring, and the sealing effect cannot be quantitatively evaluated. In terms of intelligent control, the existing system is decentralized, lacks an integrated central control platform, crack monitoring methods are limited, equipment fault early warning capabilities are weak, there is no effect analysis and feedback mechanism, and the corrosion resistance and high pressure resistance of underground equipment are insufficient, pipeline connections and sealing device sealing reliability are poor, and leakage and pressure loss are prone to occur.

[0004] The aforementioned technical bottlenecks hinder the realization of the synergistic benefits of permeability enhancement and CCUS, making the development of integrated and intelligent technologies an urgent need for the industry. This technology requires overcoming four core challenges: First, constructing a high-pressure, corrosion-resistant, multi-fluid transport and mixing system adapted to the mining environment to achieve precise proportioning and uniform mixing of supercritical CO2, water, and proppant; second, developing a dynamic monitoring and intelligent control mechanism for fractures to monitor fracture propagation in real time and optimize parameters; third, establishing a full-process monitoring and analysis system for CCUS to achieve end-to-end control of CO2 injection, absorption, separation, and storage; fourth, building an integrated intelligent control platform to integrate multiple modules for automated control and fault early warning; and fifth, utilizing single-phase or multi-phase fluids to achieve efficient perforation and uniform permeability enhancement in the reservoir. Summary of the Invention

[0005] To address the aforementioned technical shortcomings, the purpose of this invention is to provide a coal mine pre-fracturing sand injection and permeability enhancement (CCUS) equipment and method, providing technical support for reservoir weakening and permeability enhancement and carbon sequestration.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A coal mine carbon dioxide pre-fracturing and permeability enhancement (CCUS) device includes:

[0008] The high-pressure pumping system is used to pump fluids into the formation; the high-pressure pumping system includes a high-pressure fluid storage system and a pumping monitoring system; the high-pressure fluid storage system is used to store supercritical CO2, liquid nitrogen and other acidic or neutral fluids, including a backup of supercritical CO2 gas; the pumping monitoring system is used to monitor relevant parameters and equipment operating status of the acid gas path and water path, and to provide equipment fault alarms;

[0009] The high-pressure sand injection system is used to store solid particles as proppant, adjust the sand path pressure and flow rate, control the amount of sand added, and mix the proppant and fluid in the multiphase flow mixing chamber.

[0010] An array-type acoustic monitoring system is installed inside the rock wall to analyze the state of rock fractures in real time.

[0011] A gas liquefaction and separation system is used to separate gas components from a mixed gas transported by a multiphase fluid separator and to liquefy the separated gas.

[0012] The overall monitoring system is used to monitor the parameters of each system, control the operation of each device, analyze the state of rock fractures and CCUS effects, and achieve full-process control.

[0013] Preferably, the high-pressure injection system further includes an acid gas fluid high-pressure plunger pump, an acid gas path pump outlet valve, a water tank, a high-pressure / pulse pump, a water path pump outlet valve, and a gas-liquid mixing connector; one end of the high-pressure / pulse pump is connected to the water tank, and the other end is connected to the water path pump outlet valve; one end of the acid gas fluid high-pressure plunger pump is connected to the fluid high-pressure storage system, and the other end is connected to the acid gas path pump outlet valve, the other end of which is connected to the gas-liquid mixing connector; the gas-liquid mixing connector is connected to the high-pressure sand injection system via a high-pressure anti-corrosion hose; the acid gas fluid high-pressure plunger pump, the high-pressure / pulse pump, the path pump outlet valve, and the acid gas path pump outlet valve are electrically connected to the injection monitoring system.

[0014] Preferably, the system also includes a liquefied gas storage tank, a tee, a high-pressure corrosion-resistant connector, a high-pressure corrosion-resistant tubing string, a near-hole-end high-pressure corrosion-resistant sealer, a near-hole-bottom high-pressure corrosion-resistant sealer, a high-pressure corrosion-resistant fracturing tubing string, a corrosion-resistant high-strength drill bit, a multiphase fluid absorber, and a multiphase fluid separator; the corrosion-resistant high-strength drill bit, the high-pressure corrosion-resistant fracturing tubing string, and the high-pressure corrosion-resistant tubing string are connected sequentially; the high-pressure corrosion-resistant connector is installed on the high-pressure corrosion-resistant tubing string; the high-pressure corrosion-resistant tubing string is connected to the high-pressure sand injection system; the near-hole-bottom high-pressure corrosion-resistant sealer and the near-hole-end high-pressure corrosion-resistant sealer are sleeved and installed on the high-pressure... A multiphase fluid absorber is installed on a high-pressure corrosion-resistant fracturing string; the multiphase fluid absorber and the multiphase fluid separator are connected through a multiphase fluid transport pipeline; the multiphase fluid separator is connected to the gas liquefaction separation system through a mixed gas pipeline; a liquefied gas storage tank is connected between the high-pressure fluid storage system and the gas liquefaction separation system; one end of a tee is connected to the gas-liquid mixing connector through a high-pressure corrosion-resistant hose, and the other end is connected to the high-pressure sand injection system through a high-pressure corrosion-resistant hose; the liquefied gas storage tank, the multiphase fluid separator, and the main monitoring system are electrically connected.

[0015] Preferably, the high-pressure fluid storage system includes a supercritical CO2 storage tank, a liquid nitrogen storage tank, other acidic or neutral fluid storage tanks, a CO2 outlet valve, a liquid nitrogen outlet valve, other fluid outlet valves, a total acid gas outlet valve, an acid gas pressure sensor, and an acid gas flow sensor; one end of the total acid gas outlet valve is connected to the high-pressure acid gas plunger pump, and the other end is connected to the supercritical CO2 storage tank, the liquid nitrogen storage tank, and the other acidic or neutral fluid storage tank; the CO2 outlet valve is installed at both the supercritical CO2 storage tank and the total acid gas outlet valve. The pipeline between the outlet valves; the liquid nitrogen outlet valve is installed on the pipeline between the liquid nitrogen storage tank and the acid gas line main outlet valve; the other fluid outlet valve is installed on the pipeline between other acidic or neutral fluid storage tanks and the acid gas line main outlet valve; the acid gas line pressure sensor and the acid gas line flow sensor are installed on the pipeline between the acid gas line main outlet valve and the acid gas fluid high-pressure plunger pump; the CO2 outlet valve, liquid nitrogen outlet valve, other fluid outlet valves, acid gas line main outlet valve, acid gas line pressure sensor, and acid gas line flow sensor are electrically connected to the pumping monitoring system.

[0016] Preferably, the high-pressure sand injection system includes a sand pressure balancing valve, a sand pressure sensor, a sand flow sensor, a high-pressure corrosion-resistant sand tank, a sand adding valve, and a multiphase flow mixing chamber; the high-pressure corrosion-resistant sand tank is provided with a sand adding port; the lower end of the high-pressure corrosion-resistant sand tank is connected to the multiphase flow mixing chamber; the sand adding valve is installed on the pipeline between the high-pressure corrosion-resistant sand tank and the multiphase flow mixing chamber; the multiphase flow mixing chamber is connected between the high-pressure corrosion-resistant connector and the tee; one end of the sand pressure balancing valve is connected to the pipeline between the multiphase flow mixing chamber and the tee, and the other end is connected to the upper end of the high-pressure corrosion-resistant sand tank; the sand pressure sensor and the sand flow sensor are connected to the pipeline between the sand pressure balancing valve and the high-pressure corrosion-resistant sand tank; the sand pressure balancing valve, the sand pressure sensor, the sand flow sensor, and the sand adding valve are electrically connected to the main monitoring system.

[0017] Preferably, the pumping monitoring system includes an acid gas path monitoring system, a water path monitoring system, and a fault alarm system.

[0018] Preferably, the overall monitoring system includes an overall acid gas path monitoring system, an overall water path monitoring system, an overall sand path monitoring system, a CCUS analysis system, a rock fracture status monitoring system, a safety monitoring system, and an effect analysis system.

[0019] Preferably, a water supply valve is installed on the water tank; the water supply valve is electrically connected to the pumping monitoring system; a main pressure sensor is installed on the tee; a main flow sensor is installed on the pipeline between the tee and the high-pressure sand injection system; the main pressure sensor and the main flow sensor are electrically connected to the main monitoring system.

[0020] Preferably, a main pressure relief valve is installed on the pipeline between the high-pressure sand injection system and the high-pressure corrosion-resistant connector; the main pressure relief valve is electrically connected to the main monitoring system.

[0021] Preferably, the multiphase fluid absorber includes an absorber tube wall and an acid gas absorption plate; the acid gas absorption plate is installed inside the absorber tube wall; the acid gas absorption plate is provided with a circular hole to accommodate the passage of the high-pressure anti-corrosion tube column; and a solid-liquid flow channel is provided inside the absorber tube wall.

[0022] A method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS intelligent control in underground mines includes the following steps:

[0023] Step 1: Drill holes in the rock face using a directional drilling rig;

[0024] Step 2: Connect the high-pressure fluid storage system, high-pressure sand injection system, gas liquefaction and separation system, array-type acoustic monitoring system, pump injection monitoring system, and overall monitoring system;

[0025] Step 3: Under the overall control of the monitoring system, one or more fluids are pumped into the borehole, and the state of rock fractures is monitored in real time through an array-type acoustic monitoring system, and the fracture propagation morphology is intelligently controlled.

[0026] Step 4: Absorb, separate, and recover CO2 from the multiphase fluid after fracturing;

[0027] Step 5: Simultaneously, the monitoring system monitors and analyzes the carbon sequestration amount, capture amount, and utilization rate to achieve integrated operation of underground fracturing and permeability enhancement with carbon capture, utilization, and sequestration.

[0028] Preferably, step 3 employs a high-pressure water intelligent pumping method, specifically including:

[0029] F1. Equipment and Piping Connections: Connect the water tank to the high-pressure water pipe in the mine and install a water supply valve on the pipe. Connect the water tank to the high-pressure / pulse pump via a low-pressure hose. Connect the high-pressure / pulse pump to the water pump outlet valve via a high-pressure anti-corrosion hose. Install a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a main pressure relief valve, a tee, and a multiphase flow mixing chamber on the high-pressure anti-corrosion hose. Connect the high-pressure anti-corrosion hose to the high-pressure anti-corrosion tubing string via a high-pressure anti-corrosion connector. The high-pressure anti-corrosion tubing string is sequentially connected to a high-pressure anti-corrosion sealing device near the borehole opening, a high-pressure anti-corrosion fracturing tubing string, a high-pressure anti-corrosion sealing device near the bottom of the borehole, and a high-strength anti-corrosion drill bit. Install a multiphase fluid absorber at the borehole opening. Simultaneously, install an array-type acoustic monitoring system on the rock wall. Then connect all relevant equipment to the pump monitoring system and the main monitoring system via corresponding monitoring or monitoring lines. Connect the two systems via the pump monitoring system to the main system monitoring line.

[0030] F2. Pumping high-pressure liquid: Close the main pressure relief valve, sand circuit pressure balance valve, sand adding valve, and acid gas circuit pump outlet valve through the main monitoring system, and open the water circuit pump outlet valve. Monitor the water level in the tank. If the water level is less than 50%, add water to the tank through the water replenishment valve until the tank capacity reaches 90%. Monitor and adjust the water level in the tank throughout the high-pressure water pumping process. Then, start the high-pressure / pulse pump through the main monitoring system. High-pressure water enters the high-pressure anti-corrosion hose and passes sequentially through the gas-liquid mixing connector, main pressure sensor, main flow sensor, multiphase flow mixing chamber, high-pressure anti-corrosion connector, high-pressure anti-corrosion tubing string, and near-orifice high-pressure anti-corrosion hose. Corrosion-resistant fracturing tubing, high-pressure corrosion-resistant fracturing string, and near-bottom high-pressure corrosion-resistant sealer; when passing near-orifice and near-bottom high-pressure corrosion-resistant sealers, during the period when the water pressure does not exceed 5 MPa at the multiphase flow outlet pressure of the high-pressure corrosion-resistant fracturing tubing, the capsules of the near-orifice and near-bottom high-pressure corrosion-resistant sealers are opened and adhered to the rock wall, forming a fracturing sealed space; when the water pressure exceeds 5 MPa, the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing opens, high-pressure water enters the fracturing sealed space, and the water pressure acts on the rock wall. When the rock reaches the critical fracturing pressure, the rock fractures, forming hydraulic fractures;

[0031] F3. After the high-pressure water and rock have interacted, the high-pressure / pulse pump is shut down through the main monitoring system, and then the pressure relief valve is opened until the pressure in the pipeline is less than 0.2 MPa, at which point the fracturing is complete.

[0032] F4. Move the pipeline to the next fracturing borehole and repeat F1 to F3 to complete the regional intelligent fracturing operation.

[0033] Preferably, the entire process of implementing the high-pressure water intelligent pumping method is controlled by the central monitoring system, which controls the operation of all equipment. The array-type acoustic monitoring system monitors and inverts the crack propagation morphology in real time, and adjusts the parameters of each system to make the crack propagate along the required path.

[0034] Preferably, step 3 employs a high-pressure liquefied gas intelligent pump injection method, specifically including:

[0035] G1. Equipment and Piping Connections: Connect the supercritical CO2 storage tank, liquid nitrogen storage tank, and other acidic or neutral fluid storage tanks in parallel. The supercritical CO2 storage tank is connected to the CO2 outlet valve via a high-pressure corrosion-resistant hose. The liquid nitrogen storage tank is connected to the liquid nitrogen outlet valve via a high-pressure corrosion-resistant hose. The other acidic or neutral fluid storage tanks are connected to the outlet valves of other fluids via high-pressure corrosion-resistant hoses. Connect the multiple lines in parallel via a four-way valve. Connect the acid gas line main outlet valve, acid gas line pressure sensor, and acid gas line flow sensor sequentially via high-pressure corrosion-resistant hoses to form a high-pressure fluid storage system. The high-pressure fluid storage system is connected to the acid gas fluid high-pressure plunger pump via a low-pressure corrosion-resistant hose. The acid gas fluid high-pressure plunger pump is connected to the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a main pressure relief valve, and a multiphase flow mixing chamber. The high-pressure corrosion-resistant hose is connected to a high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is sequentially connected to a near-hole high-pressure corrosion-resistant sealing device, a high-pressure corrosion-resistant fracturing tubing string, a near-hole bottom high-pressure corrosion-resistant sealing device, and a corrosion-resistant high-strength drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock wall. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are connected through the pump monitoring system to the main system monitoring line.

[0036] G2. Pump in high-pressure acid gas fluid; close the main pressure relief valve, sand pressure balance valve, sand adding valve, and water pump outlet valve through the main monitoring system, and open the acid gas pump outlet valve and the main acid gas outlet valve; monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank should be prepared; then, control the opening of one of the supercritical CO2 outlet valve, liquid nitrogen outlet valve, or other fluid outlet valves through the main monitoring system, while keeping the other two closed; control the start of the high-pressure plunger pump for acid gas fluid through the main monitoring system, and the high-pressure acid fluid or neutral gas enters the high-pressure anti-corrosion system. The etching tubing sequentially passes through a tee, a main pressure sensor, a main flow sensor, a multiphase flow mixing chamber, a high-pressure corrosion-resistant connector, a high-pressure corrosion-resistant tubing string, a near-orifice high-pressure corrosion-resistant sealer, a high-pressure corrosion-resistant fracturing tubing string, and a near-bottom high-pressure corrosion-resistant sealer. When passing the near-orifice and near-bottom high-pressure corrosion-resistant sealers, if the acid gas fluid pressure exceeds 5 MPa, the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing string opens, allowing acidic or neutral fluid to enter the fracturing confined space. The acidic and neutral fluids act on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense network of fractures.

[0037] G3. After the interaction between the acid gas fluid and the rock is completed, the acid gas outlet valve and the main outlet valve of the acid gas line are closed sequentially through the main monitoring system. Then, the high-pressure plunger pump of the acid gas fluid is turned off. After waiting for 3 minutes, the pressure relief valve is slowly opened until the pressure in the pipeline is less than 0.15 MPa, and the fracturing is completed.

[0038] G4. Move the pipeline to the next fracturing borehole and repeat G1 to G3 to complete the regional intelligent fracturing operation.

[0039] Preferably, the entire process of the high-pressure liquefied gas intelligent pump injection method is controlled by a central monitoring system, which controls the operation of all equipment. The array-type acoustic monitoring system monitors and inverts the crack propagation morphology in real time, and adjusts the parameters of each system to make the crack propagate along the required path.

[0040] Preferably, step 3 employs a solid-liquid two-phase mixing intelligent pumping method, specifically including:

[0041] SF1. Equipment and Piping Connections: Connect the water tank to the high-pressure water pipe in the mine, and install a water supply valve on the pipe. The water tank is connected to the high-pressure / pulse pump via a low-pressure hose. The high-pressure / pulse pump is connected to the water pump outlet valve via a high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a high-pressure sand injection system, a main pressure relief valve, and a tee. The high-pressure sand injection system consists of a tee on the high-pressure corrosion-resistant hose; one tee connects to the multiphase flow mixing chamber, and the other connects to the sand pressure balancing valve. The sand pressure balancing valve is connected sequentially to the sand pressure sensor, sand flow sensor, and high-pressure corrosion-resistant sand tank via the high-pressure corrosion-resistant hose. A sand-adding valve is connected to a multiphase flow mixing chamber via a high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant sand tank is equipped with a sand-adding port. The high-pressure corrosion-resistant hose is connected to a high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is sequentially connected to a high-pressure corrosion-resistant sealing device near the borehole opening, a high-pressure corrosion-resistant fracturing tubing string, a high-pressure corrosion-resistant sealing device near the bottom of the borehole, and a high-strength corrosion-resistant drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock wall. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are connected to the main system monitoring line via the pump monitoring system.

[0042] SF2, high-pressure liquid injection: Close the main pressure relief valve, sand circuit pressure balancing valve, sand adding valve, and acid gas circuit pump outlet valve via the main monitoring system. Open the water circuit pump outlet valve and monitor the water level in the tank. If the water level is less than 50%, add water to the tank until it reaches 90% capacity by controlling the water replenishment valve. Monitor and adjust the water level in the tank throughout the high-pressure water injection process. Before injection, observe the sand level in the high-pressure anti-corrosion sand tank via the main monitoring system. When the sand level is less than 50%, open the sand adding valve via the monitoring system until the sand level in the sand tank exceeds 90%, then close the sand adding valve. Next, start the high-pressure / pulse pump via the main monitoring system. High-pressure water enters the high-pressure anti-corrosion hose, passing sequentially through the gas-liquid mixing connector, the main pressure sensor, and the main flow meter. The system consists of a sensor, a multiphase flow mixing chamber, a high-pressure corrosion-resistant connector, a high-pressure corrosion-resistant tubing string, a near-orifice high-pressure corrosion-resistant sealer, a high-pressure corrosion-resistant fracturing tubing string, and a near-bottom high-pressure corrosion-resistant sealer. When the water pressure passes through the near-orifice and near-bottom high-pressure corrosion-resistant sealers, and before the water pressure exceeds 5 MPa at the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing string, the capsules of these sealers are expanded to fit against the rock wall, forming a sealed fracturing space. When the water pressure exceeds 5 MPa, the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing string opens, allowing high-pressure water to enter the sealed fracturing space. The water pressure acts on the rock wall, and when the rock reaches the critical fracturing pressure, it fractures, forming a hydraulic fracture.

[0043] SF3 is pumped into a solid-liquid two-phase mixture. After a period of high-pressure fluid pumping, the pipeline pressure is reduced to 6-8 MPa. Then, the sand pressure balancing valve is opened, and the sand addition valve opening is slowly adjusted through the main monitoring system. The sand injection ratio is calculated based on the reduction in sand volume. Solid particles and high-pressure liquid mix in the multiphase flow mixing chamber to form a solid-liquid two-phase fluid. The solid-liquid two-phase flow passes through a high-pressure anti-corrosion hose, a high-pressure anti-corrosion connector, a high-pressure anti-corrosion tubing string, a high-pressure anti-corrosion seal near the wellhead, a high-pressure anti-corrosion fracturing tubing string, and a high-pressure anti-corrosion seal near the bottom of the well. When passing through the high-pressure anti-corrosion fracturing tubing string, the fluid enters the fracturing sealed space through the multiphase flow outlet, and then enters the liquid fracturing fracture, further expanding the fracture to form a dense fracture network, supporting the fracture, reducing fracture aperture changes, and maintaining high fracture conductivity.

[0044] After the interaction of SF4 and solid-liquid two-phase flow with the rock is completed, the sand injection valve is slowly closed by controlling the main monitoring system. After the sand injection valve is closed for 3 minutes, the high-pressure / pulse pump is closed by controlling the main monitoring system, and then the pressure relief valve is opened until the pressure in the pipeline is less than 0.25 MPa, and the fracturing is completed.

[0045] SF5. Move the pipeline to the next fracturing borehole and repeat SF1 to SF4 to complete the regional intelligent fracturing operation.

[0046] Preferably, the solid-liquid two-phase mixing intelligent pumping method is implemented throughout the entire process, with the operation of all equipment controlled by the central monitoring system, and the array-type acoustic monitoring system monitoring and inverting the crack propagation morphology in real time, adjusting the parameters of each system to make the crack propagate along the required path.

[0047] Preferably, step 3 employs a solid-gas two-phase mixing intelligent pumping method, specifically including:

[0048] SG1. Equipment and Piping Connections: Supercritical CO2 storage tanks, liquid nitrogen storage tanks, and other acidic or neutral fluid storage tanks are connected in parallel. The supercritical CO2 storage tank is connected to the CO2 outlet valve via a high-pressure corrosion-resistant hose. The liquid nitrogen storage tank is connected to the liquid nitrogen outlet valve via a high-pressure corrosion-resistant hose. Other acidic or neutral fluid storage tanks are connected to other fluid outlet valves via high-pressure corrosion-resistant hoses. Multiple lines are connected in parallel via a four-way valve. The acid gas path main outlet valve, acid gas path pressure sensor, and acid gas path flow sensor are sequentially connected via high-pressure corrosion-resistant hoses to form a high-pressure fluid storage system. The high-pressure fluid storage system is connected to an acid gas fluid high-pressure plunger pump via a low-pressure corrosion-resistant hose. The acid gas fluid high-pressure plunger pump is connected to the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a high-pressure sand injection system, a main pressure relief valve, and a three-way valve. The high-pressure sand injection system operates under high pressure... A three-way valve is installed on the corrosion-resistant hose. One way connects to the multiphase flow mixing chamber, and the other way connects to the sand path pressure balancing valve. The sand path pressure balancing valve is connected in sequence to the sand path pressure sensor, sand path flow sensor, high-pressure corrosion-resistant sand tank, and sand adding valve via the high-pressure corrosion-resistant hose. The sand adding valve is connected to the multiphase flow mixing chamber via the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant sand tank is equipped with a sand adding port. The high-pressure corrosion-resistant hose is connected to the high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is connected in sequence to the high-pressure corrosion-resistant sealing device near the borehole opening, the high-pressure corrosion-resistant fracturing tubing string, the high-pressure corrosion-resistant sealing device near the bottom of the borehole, and the corrosion-resistant high-strength drill bit. A multiphase fluid absorber is installed at the borehole opening. At the same time, an array-type acoustic monitoring system is installed on the rock wall. Then, all relevant equipment is connected to the pump monitoring system and the main monitoring system via corresponding monitoring or monitoring lines. The two systems are connected to the main system monitoring line through the pump monitoring system.

[0049] SG2. Pumping high-pressure acid gas fluid; close the main pressure relief valve, sand pressure balance valve, sand adding valve, and water pump outlet valve through the main monitoring system, and open the acid gas pump outlet valve and the main acid gas outlet valve; monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank should be prepared; in addition, before pumping, observe the sand storage volume in the high-pressure anti-corrosion sand tank through the main monitoring system. When the sand storage volume is less than 50%, control the sand adding valve to open through the monitoring system until the sand volume in the sand tank exceeds 90%, then close the sand adding valve; then, control the opening of one of the acid gas outlet valves—the supercritical CO2 outlet valve, liquid nitrogen outlet valve, or other fluid outlet valve—through the main monitoring system, while keeping the other two closed; through the main monitoring system... The control system starts the high-pressure plunger pump for acid gas fluid. High-pressure acid fluid or neutral gas enters the high-pressure anti-corrosion hose and passes sequentially through the gas-liquid mixing connector, the main pressure sensor, the main flow sensor, the multiphase flow mixing chamber, the high-pressure anti-corrosion connector, the high-pressure anti-corrosion tubing string, the high-pressure anti-corrosion seal near the wellhead, the high-pressure anti-corrosion fracturing tubing string, and the high-pressure anti-corrosion seal near the bottom of the well. When the acid gas fluid pressure exceeds 5MPa after passing through the high-pressure anti-corrosion seal near the wellhead and the high-pressure anti-corrosion seal near the bottom of the well, the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing string opens, and the acid or neutral fluid enters the fracturing sealed space. The acid and neutral fluids act on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense fracture network structure.

[0050] SG3. Pumping solid-gas two-phase mixed fluid: After pumping the acid gas fluid for a period of time, reduce the pipeline pressure to 6-8 MPa, then open the sand pressure balancing valve, and slowly adjust the sand addition valve opening through the main monitoring system. Calculate the injection sand ratio based on the sand reduction. Solid particles and high-pressure acid gas fluid mix in the multiphase flow mixing chamber to form a solid-gas two-phase fluid. The solid-gas two-phase flow passes through high-pressure anti-corrosion hoses, high-pressure anti-corrosion connectors, high-pressure anti-corrosion tubing, near-hole high-pressure anti-corrosion sealing device, high-pressure anti-corrosion fracturing tubing, and near-hole bottom high-pressure anti-corrosion sealing device. When passing through the high-pressure anti-corrosion fracturing tubing, it enters the fracturing sealed space through the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing, and then enters the acid gas fluid fracturing fracture, further expanding the fracture to form a dense fracture network, supporting the fracture, reducing fracture opening changes, and maintaining high fracture conductivity.

[0051] After the interaction between the solid-gas two-phase fluid and the rock is completed, the sand pressure balance valve and sand addition valve are closed sequentially through the main monitoring system. After 3 minutes, the acid gas outlet valve and the main outlet valve of the acid gas line are closed sequentially through the main monitoring system. Then, the acid gas fluid high-pressure plunger pump is turned off. After another 3 minutes, the pressure relief valve is slowly opened until the pressure in the pipeline is less than 0.25 MPa, and the fracturing is completed.

[0052] SG5. Move the pipeline to the next fracturing borehole and repeat SG1 to SG4 to complete the regional intelligent fracturing operation.

[0053] Preferably, the solid-gas two-phase mixing intelligent pumping method is implemented throughout the entire process, with the operation of all equipment controlled by the central monitoring system, and the array-type acoustic monitoring system monitoring and inverting the crack propagation morphology in real time, adjusting the parameters of each system to make the crack propagate along the required path.

[0054] Preferably, step 3 employs a solid-liquid-gas multiphase mixing intelligent pumping method, specifically including:

[0055] SFG1, Equipment and Piping Connections: Connect the supercritical CO2 storage tank, liquid nitrogen storage tank, and other acidic or neutral fluid storage tanks in parallel. The supercritical CO2 storage tank is connected to the CO2 outlet valve via a high-pressure corrosion-resistant hose. The liquid nitrogen storage tank is connected to the liquid nitrogen outlet valve via a high-pressure corrosion-resistant hose. Other acidic or neutral fluid storage tanks are connected to the outlet valves of other fluids via high-pressure corrosion-resistant hoses. Connect the multiple lines in parallel using a four-way valve. Then, sequentially connect the acid gas path main outlet valve, acid gas path pressure sensor, and acid gas path flow sensor via high-pressure corrosion-resistant hoses. The system forms a high-pressure fluid storage system. The high-pressure fluid storage system is connected to a high-pressure plunger pump for acid gas fluid via a low-pressure corrosion-resistant hose. The high-pressure plunger pump for acid gas fluid is connected to a high-pressure corrosion-resistant hose. A water tank is connected to a high-pressure water pipe in the mine, and a water supply valve is installed on the pipeline. The water tank is connected to a high-pressure / pulse pump via a low-pressure hose. The high-pressure / pulse pump is connected to the outlet valve of the water pump via a high-pressure corrosion-resistant hose. The outlet valves of the water pump and the acid gas pump are connected to a gas-liquid mixing connector via high-pressure corrosion-resistant hoses, and then connected to a high-pressure corrosion-resistant hose. Subsequently, a main pressure sensor, a main flow sensor, a high-pressure sand injection system, and a main pressure relief valve are installed on the high-pressure corrosion-resistant hose. The high-pressure sand injection system consists of a tee valve installed on the high-pressure corrosion-resistant hose; one tee connects to the multiphase flow mixing chamber, and the other connects to the sand pressure balancing valve. The sand pressure balancing valve is connected sequentially to the sand pressure sensor, sand flow sensor, high-pressure corrosion-resistant sand tank, and sand adding valve via the high-pressure corrosion-resistant hose. The sand adding valve is connected to the multiphase flow mixing chamber via the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant sand tank is equipped with a sand adding port. The corrosion-resistant hose is connected to the high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is then sequentially connected to the high-pressure corrosion-resistant sealing device near the borehole opening, the high-pressure corrosion-resistant fracturing tubing string, the high-pressure corrosion-resistant sealing device near the bottom of the borehole, and the corrosion-resistant high-strength drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock wall. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are then connected to the main system monitoring line via the pump monitoring system.

[0056] SFG2, pumping high-pressure acid gas fluid; close the main pressure relief valve, sand pressure balance valve, and sand adding valve through the main monitoring system, and open the acid gas pump outlet valve, acid gas main outlet valve, and water pump outlet valve; monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank should be prepared; monitor the water volume in the water tank. If the water volume is less than 50%, add water to the water tank by controlling the water replenishment valve until it reaches 90% of the water tank capacity. Monitor and adjust the water volume in the water tank throughout the high-pressure water pumping process; in addition, before pumping, observe the sand storage in the high-pressure anti-corrosion sand tank through the main monitoring system. When the sand storage is less than 50%, control the sand adding valve to open through the monitoring system until the sand volume in the sand tank exceeds 90%, and then close the sand adding valve;

[0057] Next, the main monitoring system controls the opening of one of the following acid gas outlet valves: supercritical CO2 outlet valve, liquid nitrogen outlet valve, or other fluid outlet valves, while the other two remain closed. The main monitoring system also controls the start of the high-pressure plunger pump for acid gas, allowing high-pressure acidic fluid or neutral gas to enter the high-pressure anti-corrosion hose. Simultaneously, the main monitoring system controls the start of the high-pressure / pulse pump, allowing high-pressure water to enter the high-pressure anti-corrosion hose. The gas and liquid phases are mixed within the gas-liquid mixing connector, and then the two-phase fluids enter the high-pressure anti-corrosion hose, passing sequentially through the tee and the main pressure sensor. The system includes a flow sensor, a multiphase flow mixing chamber, a high-pressure corrosion-resistant connector, a high-pressure corrosion-resistant tubing string, a near-orifice high-pressure corrosion-resistant sealer, a high-pressure corrosion-resistant fracturing tubing string, and a near-bottom high-pressure corrosion-resistant sealer. When the pressure of the gas-liquid two-phase fluid exceeds 5 MPa, the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing string opens, allowing the gas-liquid two-phase fluid to enter the fracturing sealed space. The gas-liquid two-phase fluid acts on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense network of cracks.

[0058] SFG3: Pumping a solid-liquid-gas multiphase mixture; After pumping the gas-liquid two-phase fluid for a period of time, reduce the pipeline pressure to 6-8 MPa, then open the sand pressure balancing valve, and slowly adjust the sand addition valve opening through the main monitoring system, calculating the injection sand ratio based on the sand reduction; Solid particles and high-pressure gas-liquid two-phase fluid are mixed in the multiphase flow mixing chamber to form a solid-liquid-gas multiphase fluid; The solid-liquid-gas multiphase fluid passes through a high-pressure anti-corrosion hose, a high-pressure anti-corrosion connector, a high-pressure anti-corrosion tubing string, a high-pressure anti-corrosion sealer near the wellhead, a high-pressure anti-corrosion fracturing tubing string, and a high-pressure anti-corrosion sealer near the bottom of the well; When passing through the high-pressure anti-corrosion fracturing tubing string, it enters the fracturing sealed space through the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing string, and then enters the gas-liquid two-phase fluid fracturing fracture, further expanding the fracture, forming a dense fracture network, supporting the fracture, reducing the fracture opening change, and maintaining the high conductivity of the fracture;

[0059] After the interaction of SFG4, solid-liquid-gas multiphase fluid, and rock is completed, the sand pressure balance valve and sand addition valve are closed sequentially through the main monitoring system. After 3 minutes, the acid gas outlet valve and the main acid gas outlet valve are closed sequentially through the main monitoring system. Then, the acid gas fluid high-pressure plunger pump and high-pressure / pulse pump are shut down. After another 3 minutes, the pressure relief valve is slowly opened until the pressure in the pipeline is less than 0.3 MPa, at which point the fracturing is complete.

[0060] SFG5: Move the pipeline to the next fracturing borehole and repeat SFG1 to SFG4 to complete the regional intelligent fracturing operation.

[0061] Preferably, the solid-liquid-gas multiphase mixing intelligent pumping method is implemented throughout the entire process, with the operation of all equipment controlled by the central monitoring system, and the array-type acoustic monitoring system monitoring and inverting the crack propagation morphology in real time, adjusting the parameters of each system to make the crack propagate along the required path.

[0062] Preferably, in step 3, the method for intelligently controlling the crack propagation morphology includes:

[0063] 1) Unidirectional crack control to crack network expansion: When monitoring shows that the crack is expanding in a single direction, if only water is injected, increase the pulsation frequency of the water injection. Through the pulsating effect of the water flow, fatigue damage is formed on the crack surface, thereby breaking the control of the ground stress and forming microcracks on the inner wall of the crack. After the microcracks are formed, observe the cracks to start expanding. When the amplitude of the expansion length change decreases, reduce the water injection frequency and increase the discharge rate. Use high discharge rate to impact the microcracks, causing the microcracks to expand and form a crack network. If the effect is still not good, the frequency can be adjusted multiple times to allow the crack network to develop fully.

[0064] 2) The crack network is controlled to be unidirectional crack propagation; when the monitoring and inversion show that the crack propagation is multidirectional crack network, such as only water injection, the fluid pressure and frequency are gradually reduced, and the crack direction is observed to gradually change from multidirectional to unidirectional. By reducing the water pressure and flow range, the crack is made to propagate only along the most easily propagating direction, and then the crack propagation direction is adjusted to maintain the crack propagation direction.

[0065] 3) Fracture network boundary control methods: ① If it is necessary to control the fractures from intersecting, and only through seepage migration, when the distance between the fracture network and the previous fracture network is 1m, reduce the fluid pressure and flow rate to stop the fractures from extending further. Increase the number of fractures within the existing fracture network only through low-volume, high-frequency pulsation. A small amount of solid can also be added to block micro-fractures, reduce fracture filtration efficiency, and improve the overall permeability of the area, thereby increasing production. ② When it is necessary to control the fractures from intersecting, allowing the fracture network to connect, once the fracture network is connected, the fluid pressure does not need to overcome the tensile strength of the rock, thus gradually decreasing, causing the fractures to expand slowly or even stop. At this time, there are fewer fractures at the fracture network boundary. It is necessary to increase the pulsation frequency and flow rate to ensure that the fluid loss is less than the injection volume, thereby promoting the expansion of the fracture network at the boundary, improving the permeability of the two borehole sections, and thus improving the flow conductivity of the fracture network. If the fracture network effect monitored by acoustic signals is still not ideal, the proportion of solid in the fluid can be increased to block micro-fracture channels, reduce fluid loss, increase fluid resistance, and thus allow the fracture network to develop more fully.

[0066] 4) Initial weakening of the fracture network: In the early stage of fracture propagation, in order to make the fractures propagate evenly in multiple directions, acidic fluid can be injected into the fractures for a period of time to weaken the rock layer and reduce the strength of the rock layer. Through the phase change of the gas, a relatively dense fracture network is formed in the closed section. Then, high-volume fracturing is carried out, combined with sand addition, to achieve the purpose of fully developing the fracture network.

[0067] Preferably, in step 5, the CCUS intelligent monitoring method is used to monitor and analyze carbon sequestration, capture, and utilization rates, specifically including:

[0068] The carbon content change (Q1) in the high-pressure fluid storage system is monitored by the overall monitoring system; the absorption rate (Q2) of the multiphase fluid absorber is monitored by the absorber monitoring line; and the CO2 content (Q3) and other carbon contents (Q4) separated from the mixed gas are monitored by the gas liquefaction separation system monitoring line. The carbon sequestration amount, capture amount, and utilization rate are calculated, with the carbon sequestration amount being Q. C =Q1-Q2-Q3, carbon capture amount is Q B =Q2+Q4, carbon utilization rate is Q L =1-(Q2+Q3) / Q1.

[0069] Preferably, when injecting acidic fluid into the borehole, the gas flowing out or seeping into the borehole is recovered. Specifically, for acidic gas, at the borehole opening, part of the gas is first absorbed by an acidic gas absorption plate. The remaining gas and solid-liquid multiphase fluid enter the multiphase fluid transport pipeline and reach the multiphase fluid separator. In the separator, the solid-liquid-gas multiphase fluid settles at the bottom, followed by the liquid, and then the gas. A solid-liquid discharge valve is installed at the bottom of the multiphase fluid separator. When the main monitoring system detects solid-liquid discharge in the separator... When the liquid level reaches 70% of the total volume of the separator, open the lower solid-liquid discharge valve to discharge the solid and liquid fluids. When the liquid level reaches 10% of the total volume of the separator, close the lower solid-liquid discharge valve. Connect a gas pipeline to the top of the multiphase fluid separator to deliver the gas to the gas liquefaction separation system. Then, the gas liquefaction separation system separates the multiple components in the mixed gas. Next, the liquefied gas or supercritical gas is stored in the corresponding liquefied gas storage tank. Then, the liquefied gas or supercritical gas in the liquefied gas storage tank is poured into the acid gas fluid storage tank.

[0070] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0071] 1. This invention designs a CO2 pre-fracturing sand injection and permeability enhancement and CCUS intelligent control equipment for underground mines, and provides an intelligent control method for CO2 pre-fracturing sand injection, realizing an integrated intelligent control process of "fracturing and permeability enhancement-CCUS" in underground mines, solving the coordination problem of the two operating independently in the past.

[0072] 2. This invention provides an intelligent pumping method for six types of fluids, including liquid phase, acid gas fluid, solid-liquid two-phase flow, solid-gas two-phase flow, gas-liquid two-phase flow, and solid-liquid-gas multiphase flow, and clarifies the control parameters for each fluid, breaking through the limitation of the single type of traditional fracturing fluid.

[0073] 3. The present invention designs a pumping monitoring system (including acid gas path monitoring, water path monitoring, and fault alarm modules) and a central monitoring system to form a dual control architecture. The central monitoring system can observe and control the operation of the pumping system in real time, and at the same time realize timely early warning of equipment failure, greatly improving the system's safety redundancy.

[0074] 4. This invention provides a method for intelligent control of rock fracture morphology, including unidirectional fracture control to fracture network expansion, fracture network control to unidirectional fracture expansion, fracture network boundary control, and initial weakening of the fracture network. The fracture morphology is inverted by an array-type acoustic monitoring system, and the direction and morphology of fracture expansion are intelligently adjusted by a total monitoring system.

[0075] 5. This invention designs an intelligent monitoring and analysis process for carbon capture, storage and utilization, clarifies the calculation methods for carbon storage capacity, carbon capture capacity and carbon utilization rate, realizes quantitative evaluation of CCUS effect, and makes up for the lack of data support in the past.

[0076] 6. The intelligent control system of this invention includes a multiphase separation and recovery system, which separates solid, liquid and gas after fracturing through a multiphase fluid absorber (with built-in acid gas absorption plate), a multiphase fluid separator and a gas liquefaction separation system. After CO2 is liquefied, it is reinjected into the storage tank for recycling, thereby improving resource utilization and reducing emissions.

[0077] 7. The entire set of equipment of this invention (high pressure anti-corrosion hose, sealing device, drill rod, sand jar, etc.) has high pressure anti-corrosion performance and is suitable for the complex environment of high pressure and acidic fluid erosion in mines.

[0078] 8. This invention can automatically monitor the water level in the water tank and the amount of sand in the sand container. When the water level in the water tank is less than 50%, it will automatically replenish water to 90% and when the amount of sand in the sand container is less than 50%, it will automatically replenish sand to 90%, without the need for manual intervention, thus solving the problem of frequent interruptions in traditional construction due to insufficient materials.

[0079] 9. In the early stage of fracturing, the present invention injects acidic fluid to weaken the rock layer strength, and combined with the gas phase change, forms dense micro-fractures in the closed section, creating conditions for subsequent large-volume fracturing and sand addition, and improving the development density of coal seam fracture network.

[0080] 10. The overall monitoring system of this invention integrates seven major modules: overall acid gas path monitoring, overall water path monitoring, overall sand path monitoring, CCUS analysis, rock fracture status monitoring, safety monitoring, and effect analysis, to achieve full-process parameter visualization and control.

[0081] 11. After fracturing is completed, the pipeline can be moved directly to the next borehole for repeated operation without rebuilding the core system, realizing regional continuous intelligent control of fracturing operation and greatly improving the overall construction efficiency.

[0082] 12. The present invention installs a multiphase fluid absorber at the borehole opening, which preferentially absorbs overflowing acidic gases such as CO2 through an internal acidic gas absorption plate, thereby reducing the gas concentration in the work area and ensuring the breathing safety of construction personnel. Traditional fracturing lacks such protective measures.

[0083] 13. This invention fills the fractures with solid proppant in a solid-liquid-gas multiphase fluid to prevent the fractures from closing due to the elastic recoil of the rock strata after fracturing, thus maintaining the high conductivity of the fractures for a long time. Traditional CO2 fracturing in mines is prone to fracture instability due to the lack of proppant.

[0084] 14. The overall monitoring system of this invention can evaluate the fracturing effect in real time based on array-type acoustic monitoring data and CCUS data, and optimize subsequent pumping parameters, sand ratio and pressure in reverse, forming a "monitoring-analysis-optimization" closed loop. Traditional fracturing does not have a real-time feedback optimization mechanism. Attached Figure Description

[0085] Figure 1 This is a structural block diagram of the present invention;

[0086] Figure 2 This is a schematic diagram of the multiphase fluid absorber in this invention;

[0087] Figure 3 for Figure 2 Cross-sectional view along the AA direction.

[0088] in:

[0089] 1. High-pressure fluid storage system; 1-1. Supercritical CO2 storage tank; 1-2. Liquid nitrogen storage tank; 1-3. Other acidic or neutral fluid storage tanks; 1-4. CO2 outlet valve; 1-5. Liquid nitrogen outlet valve; 1-6. Other fluid outlet valves; 1-7. CO2 outlet valve monitoring line; 1-8. Liquid nitrogen outlet valve monitoring line; 1-9. Other fluid outlet valve monitoring line; 1-10. Acid gas path main outlet valve; 1-11. Acid gas path pressure sensor; 1-12. Acid gas path flow sensor; 1-13. Acid gas path main outlet valve monitoring line; 1-14. Acid gas path pressure sensor monitoring line; 1-15. Acid gas path flow sensor monitoring line;

[0090] 2. High-pressure plunger pump for acid gas fluid; 2-1. Monitoring line for high-pressure plunger pump for acid gas fluid;

[0091] 3. Acid gas pump outlet valve; 3-1. Acid gas pump outlet valve monitoring line;

[0092] 4. Water supply valve; 4-1. Water supply valve monitoring line;

[0093] 5. Water tank; 5-1. Water tank level monitoring line;

[0094] 6. High-voltage / pulse pump; 6-1. High-voltage / pulse pump monitoring line;

[0095] 7. Water pump outlet valve; 7-1. Water pump outlet valve monitoring line;

[0096] 8. Gas-liquid mixing connector; 8-1. T-junction;

[0097] 9. High-pressure corrosion-resistant hoses;

[0098] 10. Main circuit pressure sensor;

[0099] 11. Total flow sensor;

[0100] 12. High-pressure sand injection system; 12-1. Sand circuit pressure balancing valve; 12-2. Sand circuit pressure sensor; 12-3. Sand circuit flow sensor; 12-4. High-pressure corrosion-resistant sand tank; 12-5. Sand adding valve; 12-6. Multiphase flow mixing chamber; 12-7. Sand adding port; 12-8. Sand circuit pressure balancing valve monitoring line; 12-9. Sand circuit pressure sensor detection line; 12-10. Sand circuit flow sensor monitoring line; 12-11. Sand adding valve monitoring line; 12-12. Sand quantity monitoring line; 12-13. Sand adding port monitoring line;

[0101] 13. Main pressure relief valve; 13-1. Main pressure relief valve monitoring line;

[0102] 14. High-pressure corrosion-resistant connector;

[0103] 15. High-pressure corrosion-resistant tubing;

[0104] 16. High-pressure corrosion-resistant borehole sealer near the borehole opening;

[0105] 17. High-pressure corrosion-resistant borehole sealer near the bottom of the hole;

[0106] 18. High-pressure corrosion-resistant fracturing tubing string; 18-1. High-pressure corrosion-resistant fracturing tubing string multiphase flow outlet;

[0107] 19. Corrosion-resistant, high-strength drill bit;

[0108] 20. Rock wall; 20-1. Array-type acoustic wave monitoring system; 20-2. Monitoring line of array-type acoustic wave monitoring system;

[0109] 21. Multiphase fluid absorber; 21-1. Acid gas absorption plate; 21-2. Absorber monitoring line; 21-3. Absorber tube wall; 21-4. Solid-liquid flow channel;

[0110] 22. Multiphase fluid transport pipelines;

[0111] 23. Multiphase fluid separator; 23-1. Multiphase fluid separator monitoring line;

[0112] 24. Mixed gas pipeline;

[0113] 25. Gas liquefaction and separation system; 25-1. Monitoring line for gas liquefaction and separation system;

[0114] 26. Liquefied petroleum gas (LPG) storage unit; 26-1. LPG storage unit monitoring line;

[0115] 27. Pumping monitoring system; 27-1. Acid gas path monitoring system; 27-2. Water path monitoring system; 27-3. Fault alarm system; 27-4. Pumping monitoring system to main system monitoring line;

[0116] 28. Overall monitoring system; 28-1. Overall acid gas path monitoring system; 28-2. Overall water path monitoring system; 28-3. Overall sand path monitoring system; 28-4. CCUS analysis system; 28-5. Rock stratum fracture status monitoring system; 28-6. Safety monitoring system; 28-7. Effect analysis system. Detailed Implementation

[0117] The invention will now be further described with reference to the accompanying drawings.

[0118] like Figures 1 to 3 As shown, a CO2 pre-fracturing and permeability enhancement (CCUS) device for mines includes a high-pressure fluid storage system 1, a high-pressure acid gas plunger pump 2, an acid gas pump outlet valve 3, a water supply valve 4, a water tank 5, a high-pressure / pulse pump 6, a water pump outlet valve 7, a gas-liquid mixing connector 8, a tee 8-1, a high-pressure corrosion-resistant hose 9, a main pressure sensor 10, a main flow sensor 11, a high-pressure sand injection system 12, a main pressure relief valve 13, a high-pressure corrosion-resistant connector 14, a high-pressure corrosion-resistant tubing string 15, a near-hole high-pressure corrosion-resistant sealing device 16, a near-hole bottom high-pressure corrosion-resistant sealing device 17, a high-pressure corrosion-resistant fracturing tubing string 18, a corrosion-resistant high-strength drill bit 19, a rock wall 20, a multiphase fluid absorber 21, a multiphase fluid transport pipeline 22, a multiphase fluid separator 23, a mixed gas pipeline 24, a gas liquefaction separation system 25, a liquefied gas storage tank 26, a pumping monitoring system 27, and a main monitoring system 28.

[0119] The high-pressure fluid storage system 1 includes: a supercritical CO2 storage tank 1-1, a liquid nitrogen storage tank 1-2, other acidic or neutral fluid storage tanks 1-3 (e.g., low-concentration hydrochloric acid, sulfuric acid, etc.), a CO2 outlet valve 1-4, a liquid nitrogen outlet valve 1-5, other fluid outlet valves 1-6, a CO2 outlet valve monitoring line 1-7, a liquid nitrogen outlet valve monitoring line 1-8, other fluid outlet valve monitoring lines 1-9, a total acid gas outlet valve 1-10, an acid gas pressure sensor 1-11, an acid gas flow sensor 1-12, a total acid gas outlet valve monitoring line 1-13, an acid gas pressure sensor monitoring line 1-14, and an acid gas flow sensor monitoring line 1-15.

[0120] The acid gas fluid high-pressure plunger pump 2 is connected to the pumping monitoring system 27 via the acid gas fluid high-pressure plunger pump monitoring line 2-1 to monitor the start and stop of the acid gas fluid high-pressure plunger pump 2 and pump the fluid in the high-pressure fluid storage system into the formation.

[0121] The acid gas pump outlet valve 3 is connected to the pumping monitoring system 27 via the acid gas pump outlet valve monitoring line 3-1 to monitor the opening and closing status of the acid gas pump outlet valve 3.

[0122] The water supply valve 4 is connected to the pump monitoring system 27 via the water supply valve monitoring line 4-1 to monitor the opening degree of the water supply valve 4.

[0123] Water tank 5 is connected to pump monitoring system 27 via water tank level monitoring line 5-1 to monitor changes in water level inside water tank 5.

[0124] The high-pressure / pulse pump 6 is connected to the pumping monitoring system 27 via the high-pressure / pulse pump monitoring line 6-1 to monitor the start and stop of the high-pressure / pulse pump 6 and pump high-pressure water into the formation at a horizontal or variable flow rate.

[0125] The water pump outlet valve 7 is connected to the pump injection monitoring system 27 via the water pump outlet valve monitoring line 7-1 to monitor the opening and closing status of the water pump outlet valve 7.

[0126] The high-pressure sand injection system 12 includes a sand pressure balancing valve 12-1, a sand pressure sensor 12-2, a sand flow sensor 12-3, a high-pressure corrosion-resistant sand tank 12-4, a sand adding valve 12-5, a multiphase flow mixing chamber 12-6, a sand adding port 12-7, a sand pressure balancing valve monitoring line 12-8, a sand pressure sensor detection line 12-9, a sand flow sensor monitoring line 12-10, a sand adding valve monitoring line 12-11, a sand quantity monitoring line 12-12, and a sand adding port monitoring line 12-13.

[0127] The sand circuit pressure balancing valve 12-1 is connected to the main monitoring system 28 via the sand circuit pressure balancing valve monitoring line 12-8 to monitor the opening and closing status of the sand circuit pressure balancing valve 12-1.

[0128] The sand pressure sensor 12-2 is connected to the main monitoring system 28 via the sand pressure sensor detection line 12-9 to monitor the sand pressure.

[0129] The sand flow sensor 12-3 is connected to the main monitoring system 28 via the sand flow sensor monitoring line 12-10 to monitor the sand flow.

[0130] The sand filling valve 12-5 is connected to the main monitoring system 28 via the sand filling valve monitoring line 12-11 to monitor the opening degree of the sand filling valve 12-5.

[0131] The high-pressure corrosion-resistant sand tank 12-4 is connected to the main monitoring system 28 via the sand quantity monitoring line 12-12 to monitor the sand quantity inside the sand tank.

[0132] The sand filling port 12-7 is connected to the main monitoring system 28 via the sand filling port monitoring line 12-13 to monitor the opening degree of the sand filling port 12-7.

[0133] The main pressure relief valve 13 is connected to the main monitoring system 28 via the main pressure relief valve monitoring line 13-1 to monitor the opening and closing status of the pressure relief valve.

[0134] The high-pressure corrosion-resistant fracturing string 18 is equipped with a multiphase flow outlet for passing through a multiphase mixture of solid, liquid, and gaseous fluids.

[0135] An array-type acoustic wave monitoring system 20-1 is installed inside the rock wall 20, and is connected to the main monitoring system 28 through the monitoring line 20-2 of the array-type acoustic wave monitoring system to analyze the state of rock fractures in real time.

[0136] The multiphase fluid absorber 21 is equipped with an acid gas absorption plate 21-1 for absorbing acid gases such as CO2. At the same time, it is connected to the main monitoring system 28 through the absorber monitoring line 21-2 to monitor information such as the flow rate of each phase of the multiphase fluid passing through the absorber.

[0137] The gas liquefaction and separation system 25 is connected to the main monitoring system through the gas liquefaction and separation system monitoring line 25-1 to monitor the gas composition and flow rate.

[0138] The LPG storage unit is connected to the main monitoring system via the LPG storage unit monitoring line to monitor the remaining LPG level.

[0139] The pumping monitoring system 27 mainly consists of three modules: the acid gas path monitoring system 27-1, the water path monitoring system 27-2, and the fault alarm system 27-3. The main monitoring system 28 can observe the status of the pumping monitoring system 27 and control its operation through the main system monitoring line 27-4.

[0140] The overall monitoring system 28 includes the overall acid gas path monitoring system 28-1, the overall water path monitoring system 28-2, the overall sand path monitoring system 28-3, the CCUS analysis system 28-4, the rock stratum fracture status monitoring system 28-5, the safety monitoring system 28-6, and the effect analysis system 28-7.

[0141] The underground CO2 pre-fracturing sand injection permeability enhancement and CCUS intelligent control method includes seven main methods, namely, high-pressure water intelligent pumping method, high-pressure liquefied gas intelligent pumping method, solid-liquid two-phase mixed intelligent pumping method, solid-gas two-phase mixed intelligent pumping method, solid-liquid-gas multi-phase mixed intelligent pumping method, rock fracture morphology intelligent control method, and CCUS intelligent monitoring method.

[0142] (1) High-pressure water intelligent pumping method

[0143] The equipment involved mainly includes: water tank 5, high pressure / pulse pump 6, water pump outlet valve 7, gas-liquid mixing connector 8, high pressure anti-corrosion hose 9, main pressure sensor 10, main flow sensor 11, main pressure relief valve 13, high pressure anti-corrosion connector 14, high pressure anti-corrosion tubing string 15, high pressure anti-corrosion sealing device near the borehole opening 16, high pressure anti-corrosion sealing device near the bottom of the borehole 17, high pressure anti-corrosion fracturing tubing string 18, anti-corrosion high-strength drill bit 19, rock wall 20, array-type acoustic monitoring system 20-1, multiphase fluid absorber 21, pumping monitoring system 27, main monitoring system 28, and corresponding monitoring lines, etc.

[0144] Includes the following steps:

[0145] F1. Drilling. Using a directional drilling rig, drill holes of the required dimensions (diameter, angle, length, etc.) into the rock face at a depth of 20 mm.

[0146] F2. Equipment and Piping Connections. Connect water tank 5 to the high-pressure water pipe in the mine, and install a water supply valve 4 on the pipeline. Water tank 5 is connected to high-pressure / pulse pump 6 through a low-pressure hose. High-pressure / pulse pump 6 is connected to water pump outlet valve 7 through high-pressure anti-corrosion hose 9. The high-pressure anti-corrosion hose 9 is equipped with a gas-liquid mixing connector 8, a main pressure sensor 10, a main flow sensor 11, a main pressure relief valve 13, a tee 8-1, a multiphase flow mixing chamber 12-6, etc. The high-pressure anti-corrosion hose 9 is connected to high-pressure anti-corrosion tubing string 15 through high-pressure anti-corrosion connector 14. The high-pressure anti-corrosion tubing string 15 is sequentially connected to a high-pressure anti-corrosion sealing device 16 near the borehole opening, a high-pressure anti-corrosion fracturing tubing string 18, a high-pressure anti-corrosion sealing device 17 near the bottom of the borehole, and an anti-corrosion high-strength drill bit 19. A multiphase fluid absorber 21 is installed at the borehole opening. At the same time, an array-type acoustic monitoring system 20-1 is installed on the rock wall 20, and then all relevant equipment is connected to the pumping monitoring system 27 and the main monitoring system 28 through corresponding monitoring or monitoring lines, and the two systems are connected to the main system monitoring line 27-4 through the pumping monitoring system.

[0147] F3. Pumping High-Pressure Liquid. After the equipment and pipeline connections are completed, close the main pressure relief valve 13, sand pressure balance valve 12-1, sand adding valve 12-5, and acid gas pump outlet valve 3 through the main monitoring system, and open the water pump outlet valve 7. Monitor the water level in the tank. If the water level is less than 50%, add water to the tank 5 through the water replenishment valve 4 until the tank capacity reaches 90%. Monitor and adjust the water level in the tank throughout the high-pressure water pumping process. Then, start the high-pressure / pulse pump 6 through the main monitoring system 28. The high-pressure water enters the high-pressure anti-corrosion hose and passes sequentially through the gas-liquid mixing connector 8, main pressure sensor 10, main flow sensor 11, multiphase flow mixing chamber 12-6, high-pressure anti-corrosion connector 14, high-pressure anti-corrosion tubing string 15, near-hole high-pressure anti-corrosion sealer 16, high-pressure anti-corrosion fracturing tubing string 18, and near-hole bottom high-pressure anti-corrosion sealer 17. After passing through the near-hole high-pressure anti-corrosion sealer 16 and near-hole bottom high-pressure anti-corrosion sealer 17, the water continues its flow through the high-pressure anti-corrosion sealer 16 and near-hole bottom high-pressure anti-corrosion sealer 17. When the water pressure does not exceed the pressure (5MPa) of the multiphase flow outlet 18-1 of the high-pressure anti-corrosion fracturing string, the capsules of the high-pressure anti-corrosion sealing device 16 near the borehole orifice and the high-pressure anti-corrosion sealing device 17 near the bottom of the borehole are opened and attached to the rock wall 20 to form a fracturing sealed space. When the water pressure exceeds 5MPa, the multiphase flow outlet of the high-pressure anti-corrosion fracturing string opens and high-pressure water enters the fracturing sealed space. The water pressure acts on the rock wall. When the rock reaches the critical fracturing pressure, the rock fractures and forms a hydraulic fracture.

[0148] F4. After the high-pressure water and rock interaction is completed, the high-pressure / pulse pump 6 is shut down by the main monitoring system 28, and then the pressure relief valve is opened until the pressure in the pipeline is less than 0.2MPa, at which point the fracturing is completed.

[0149] F5. Move the pipeline to the next fracturing borehole and repeat S1-S4 to complete the regional intelligent fracturing operation.

[0150] The entire process of high-pressure water fracturing of rocks is controlled by a central monitoring system through the monitoring lines of each device. The array-type acoustic wave monitoring system 20-1 monitors and inverts the crack propagation morphology in real time, providing a basis for the formation of dense cracks. The system also adjusts the parameters of each system through an intelligent system to make the cracks propagate along the required path.

[0151] (2) Intelligent pump injection of high-pressure liquefied gas

[0152] The equipment involved mainly includes: high-pressure fluid storage system, high-pressure plunger pump for acid gas fluid, outlet valve of acid gas circuit pump, gas-liquid mixing connector, high-pressure anti-corrosion hose, main pressure sensor, main flow sensor, multiphase flow mixing chamber, main pressure relief valve, high-pressure anti-corrosion connector, high-pressure anti-corrosion tubing string, high-pressure anti-corrosion sealing device near the borehole orifice, high-pressure anti-corrosion sealing device near the bottom of the borehole, high-pressure anti-corrosion fracturing tubing string, anti-corrosion high-strength drill bit, rock wall, array-type acoustic monitoring system, multiphase fluid absorber, pumping monitoring system, main monitoring system, and corresponding monitoring lines, etc.

[0153] Includes the following steps:

[0154] G1. Drilling. Drilling holes of the required size (diameter, angle, length, etc.) into the rock face using a directional drilling rig.

[0155] G2. Equipment and Piping Connections. Connect the supercritical CO2 storage tank 1-1, liquid nitrogen storage tank 1-2, and other acidic or neutral fluid storage tanks 1-3 in parallel. Connect the supercritical CO2 storage tank 1-1 to the CO2 outlet valve 1-4 via a high-pressure anti-corrosion hose. Connect the liquid nitrogen storage tank 1-2 to the liquid nitrogen outlet valve 1-5 via a high-pressure anti-corrosion hose. Connect the other acidic or neutral fluid storage tanks 1-3 to the outlet valves 1-6 of other fluids via high-pressure anti-corrosion hoses. Connect the multiple lines in parallel via a four-way valve. Then, connect the acid gas main outlet valve 1-10, acid gas pressure sensor 1-11, and acid gas flow sensor 1-12 in sequence via high-pressure anti-corrosion hoses to form a high-pressure fluid storage system. The high-pressure fluid storage system is connected to the acid gas high-pressure plunger pump via a low-pressure corrosion-resistant hose. The acid gas high-pressure plunger pump is connected to a high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a main pressure relief valve, and a multiphase flow mixing chamber. The high-pressure corrosion-resistant hose is connected to a high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is sequentially connected to a near-hole high-pressure corrosion-resistant sealing device, a high-pressure corrosion-resistant fracturing tubing string, a near-hole bottom high-pressure corrosion-resistant sealing device, and a corrosion-resistant high-strength drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock face. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are then connected via a line from the pump monitoring system to the main system monitoring line.

[0156] G3. Pumping high-pressure acid gas fluid. After the equipment and pipeline connections are completed, close the main line pressure relief valve 13, sand line pressure balancing valve 12-1, sand adding valve 12-5, and water line pump outlet valve 7 through the main monitoring system. Open the acid gas line pump outlet valve 3 and the acid gas line main outlet valve 1-10. Monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank needs to be prepared. Next, control the opening of one of the following acid gas outlet valves through the main monitoring system 28: supercritical CO2 outlet valve 1-4, liquid nitrogen outlet valve 1-5, or other fluid outlet valve 1-6. The other two should remain closed. The high-pressure plunger pump 2 for acid gas fluid is started by the overall monitoring system 28. High-pressure acid fluid or neutral gas enters the high-pressure anti-corrosion hose 9 and passes sequentially through the tee 8, the main pressure sensor 10, the main flow sensor 11, the multiphase flow mixing chamber 12-6, the high-pressure anti-corrosion connector 14, the high-pressure anti-corrosion tubing string 15, the high-pressure anti-corrosion sealer near the wellhead 16, the high-pressure anti-corrosion fracturing tubing string 18, and the high-pressure anti-corrosion sealer near the bottom of the well. When the acid gas fluid pressure exceeds 5MPa after passing through the high-pressure anti-corrosion sealer near the wellhead 16 and the high-pressure anti-corrosion sealer near the bottom of the well, the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing string opens, and the acid or neutral fluid enters the fracturing sealed space. The acid and neutral fluids act on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense crack network structure.

[0157] G4. After the interaction between the acid gas fluid and the rock is completed, the acid gas outlet valve and the acid gas line main outlet valve 1-10 are closed sequentially through the main monitoring system 28. Then, the acid gas fluid high-pressure plunger pump 2 is turned off. After waiting for 3 minutes, the pressure relief valve 13 is slowly opened until the pressure in the pipeline is less than 0.15 MPa, and the fracturing is completed.

[0158] G5. Move the pipeline to the next fracturing borehole and repeat G1-G4 to complete the regional intelligent fracturing operation.

[0159] The entire process of acid gas fluid fracturing of rock is controlled by a central monitoring system through the monitoring lines of each device. The array-type acoustic monitoring system 20-1 monitors and inverts the crack propagation morphology in real time, providing a basis for the formation of dense cracks. The system also adjusts the parameters of each system through an intelligent system to make the cracks propagate along the required path.

[0160] (3) Intelligent pumping of solid-liquid two-phase mixing

[0161] The equipment involved mainly includes: water tanks, high-pressure / pulse pumps, water pump outlet valves, gas-liquid mixing connectors, high-pressure corrosion-resistant hoses, main pressure sensors, main flow sensors, high-pressure sand injection systems, main pressure relief valves, high-pressure corrosion-resistant connectors, high-pressure corrosion-resistant tubing strings, near-hole high-pressure corrosion-resistant sealing devices, near-hole bottom high-pressure corrosion-resistant sealing devices, high-pressure corrosion-resistant fracturing tubing strings, corrosion-resistant high-strength drill bits, rock walls, array-type acoustic monitoring systems, multiphase fluid absorbers, pumping monitoring systems, main monitoring systems, and corresponding monitoring lines, etc.

[0162] Includes the following steps:

[0163] SF1. Drilling. Drilling holes of the required size (diameter, angle, length, etc.) into the rock face using a directional drilling rig.

[0164] SF2, Equipment and Piping Connections. The water tank is connected to the high-pressure water pipe in the mine, and a water supply valve is installed on the pipeline. The water tank is connected to the high-pressure / pulse pump via a low-pressure hose. The high-pressure / pulse pump is connected to the water pump outlet valve via a high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a high-pressure sand injection system, a main pressure relief valve, and a tee. The high-pressure sand injection system consists of a tee on the high-pressure corrosion-resistant hose. One tee connects to the multiphase flow mixing chamber, and the other connects to the sand pressure balancing valve 12-1. The sand pressure balancing valve is connected sequentially via the high-pressure corrosion-resistant hose to the sand pressure sensor 12-2, the sand flow sensor 12-3, the high-pressure corrosion-resistant sand tank 12-4, and the sand adding valve 12-5. The sand adding valve is connected to the multiphase flow mixing chamber via the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant sand tank has a sand adding port. High-pressure corrosion-resistant hoses are connected to high-pressure corrosion-resistant tubing strings via high-pressure corrosion-resistant connectors. These tubing strings are then sequentially connected to a near-hole high-pressure corrosion-resistant sealing device, a high-pressure corrosion-resistant fracturing tubing string, a near-hole bottom high-pressure corrosion-resistant sealing device, and a high-strength corrosion-resistant drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock face. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are then connected via a line from the pump monitoring system to the main system monitoring line.

[0165] SF3, high-pressure liquid injection. After the equipment and pipeline connections are completed, close the main pressure relief valve 13, sand circuit pressure balancing valve 12-1, sand adding valve 12-5, and acid gas circuit pump outlet valve 3 through the main monitoring system, and open the water circuit pump outlet valve 7. Monitor the water level in the water tank. If the water level is less than 50%, add water to the water tank 5 by controlling the water replenishment valve 4 until the water tank capacity reaches 90%. Monitor and adjust the water level in the tank throughout the high-pressure water injection process. Before injection, observe the sand level in the high-pressure anti-corrosion sand tank through the main monitoring system. When the sand level is less than 50%, open the sand adding valve 12-7 through the monitoring system until the sand level in the sand tank exceeds 90%, then close the sand adding valve 12-7. Next, the high-pressure / pulse pump 6 is started via the main monitoring system 28. High-pressure water enters the high-pressure anti-corrosion hose and passes sequentially through the gas-liquid mixing connector 8, the main pressure sensor 10, the main flow sensor 11, the multiphase flow mixing chamber 12-6, the high-pressure anti-corrosion connector 14, the high-pressure anti-corrosion tubing string 15, the near-hole high-pressure anti-corrosion sealer 16, the high-pressure anti-corrosion fracturing tubing string 18, and the near-hole bottom high-pressure anti-corrosion sealer 17. After passing through the near-hole high-pressure anti-corrosion sealer 16 and the near-hole bottom high-pressure anti-corrosion sealer 17, the water flows through the high-pressure anti-corrosion sealer 16 and the near-hole bottom high-pressure anti-corrosion sealer 17. When the water pressure does not exceed the pressure (5MPa) of the multiphase flow outlet 18-1 of the high-pressure anti-corrosion fracturing string, the capsules of the high-pressure anti-corrosion sealing device 16 near the borehole orifice and the high-pressure anti-corrosion sealing device 17 near the bottom of the borehole are opened and attached to the rock wall 20 to form a fracturing sealed space. When the water pressure exceeds 5MPa, the multiphase flow outlet of the high-pressure anti-corrosion fracturing string opens and high-pressure water enters the fracturing sealed space. The water pressure acts on the rock wall. When the rock reaches the critical fracturing pressure, the rock fractures and forms a hydraulic fracture.

[0166] SF4 is pumped to inject a solid-liquid two-phase mixture. High-pressure fluid is pumped for a period of time (5-10 minutes) to reduce the pipeline pressure to 6-8 MPa. Then, the sand pressure balancing valve 12-1 is opened, and the opening of the sand-adding valve 12-5 is slowly adjusted through the main monitoring system. The injection sand ratio is calculated based on the reduction in sand volume. Solid particles and high-pressure liquid mix in the multiphase flow mixing chamber to form a solid-liquid two-phase fluid. The solid-liquid two-phase flow passes through the high-pressure anti-corrosion hose 9, high-pressure anti-corrosion connector 14, high-pressure anti-corrosion tubing string 15, near-hole high-pressure anti-corrosion sealing device 16, high-pressure anti-corrosion fracturing tubing string 18, and near-hole bottom high-pressure anti-corrosion sealing device 17. While passing through the high-pressure anti-corrosion fracturing tubing string, the fluid enters the fracturing sealed space through the multiphase flow outlet, and then enters the liquid fracturing fracture, further expanding the fracture to form a dense fracture network, supporting the fracture, reducing fracture aperture changes, and maintaining high fracture conductivity.

[0167] After the interaction of SF5 and solid-liquid two-phase flow with the rock is completed, the sand injection valve 12-5 is slowly closed by the main monitoring system 28. After the sand injection valve is closed for 3 minutes, the high pressure / pulse pump 6 is closed by the main monitoring system 28, and then the pressure relief valve is opened until the pressure in the pipeline is less than 0.25 MPa, and the fracturing is completed.

[0168] SF6. Move the pipeline to the next fracturing borehole and repeat SF1-SF5 to complete the regional intelligent fracturing operation.

[0169] The entire process of rock fracturing using solid-liquid two-phase fluid is controlled by a central monitoring system through the monitoring lines of each device. The array-type acoustic monitoring system 20-1 monitors and inverts the crack propagation morphology in real time, providing a basis for the formation of dense cracks. The system also adjusts the parameters of each system through an intelligent system to make the cracks propagate along the required path.

[0170] (4) Intelligent pumping of solid-gas two-phase mixing

[0171] The equipment involved mainly includes: high-pressure fluid storage system, high-pressure plunger pump for acid gas fluid, outlet valve of acid gas circuit pump, tee, high-pressure anti-corrosion hose, main pressure sensor, main flow sensor, high-pressure sand injection system, main pressure relief valve, high-pressure anti-corrosion connector, high-pressure anti-corrosion tubing string, high-pressure anti-corrosion sealing device near the borehole orifice, high-pressure anti-corrosion sealing device near the bottom of the borehole, high-pressure anti-corrosion fracturing tubing string, anti-corrosion high-strength drill bit, rock wall, array-type acoustic monitoring system, multiphase fluid absorber, pumping monitoring system, main monitoring system, and corresponding monitoring lines, etc.

[0172] Includes the following steps:

[0173] SG1. Drilling. Drilling holes (diameter, angle, length, etc.) into the rock face using a directional drilling rig.

[0174] SG2. Equipment and Piping Connections. Supercritical CO2 storage tank 1-1, liquid nitrogen storage tank 1-2, and other acidic or neutral fluid storage tanks 1-3 are connected in parallel. Supercritical CO2 storage tank 1-1 is connected to CO2 outlet valve 1-4 via high-pressure corrosion-resistant hose. Liquid nitrogen storage tank 1-2 is connected to liquid nitrogen outlet valve 1-5 via high-pressure corrosion-resistant hose. Other acidic or neutral fluid storage tanks 1-3 are connected to other fluid outlet valves 1-6 via high-pressure corrosion-resistant hose. Multiple lines are connected in parallel via a four-way valve. The acid gas path main outlet valve 1-10, acid gas path pressure sensor 1-11, and acid gas path flow sensor 1-12 are sequentially connected via high-pressure corrosion-resistant hose to form a high-pressure fluid storage system. The high-pressure fluid storage system is connected to an acid gas fluid high-pressure plunger pump via low-pressure corrosion-resistant hose. The acid gas fluid high-pressure plunger pump is connected to a high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a high-pressure sand injection system, a main pressure relief valve, and a three-way valve. The high-pressure sand injection system consists of a tee connected to a high-pressure corrosion-resistant hose. One tee connects to a multiphase flow mixing chamber, and the other connects to a sand pressure balancing valve 12-1. This balancing valve is connected sequentially via the high-pressure corrosion-resistant hose to a sand pressure sensor 12-2, a sand flow sensor 12-3, a high-pressure corrosion-resistant sand tank 12-4, and a sand-adding valve 12-5. The sand-adding valve is connected to the multiphase flow mixing chamber via the same hose. The high-pressure corrosion-resistant sand tank has a sand-adding port. The high-pressure corrosion-resistant hose is connected to a high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. This tubing string is sequentially connected to a near-hole high-pressure corrosion-resistant sealing device, a high-pressure corrosion-resistant fracturing tubing string, a near-hole bottom high-pressure corrosion-resistant sealing device, and a high-strength corrosion-resistant drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock face. All relevant equipment is then connected to the pump injection monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are then connected via a line from the pump injection monitoring system to the main system monitoring line.

[0175] SG3. Pumping high-pressure acid gas fluid. After the equipment and pipeline connections are completed, close the main line pressure relief valve 13, sand line pressure balancing valve 12-1, sand adding valve 12-5, and water line pump outlet valve 7 through the main monitoring system. Open the acid gas line pump outlet valve 3 and the acid gas line main outlet valve 1-10. Monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank should be prepared. In addition, before pumping, observe the sand storage in the high-pressure anti-corrosion sand tank through the main monitoring system. When the sand storage is less than 50%, control the sand adding valve 12-7 to open through the monitoring system until the sand volume in the sand tank exceeds 90%, then close the sand adding valve 12-7. Next, control the opening of one of the following acid gas outlet valves through the main monitoring system 28: supercritical CO2 outlet valve 1-4, liquid nitrogen outlet valve 1-5, or other fluid outlet valve 1-6. The other two should be closed. The high-pressure plunger pump 2 for acid gas fluid is started by the overall monitoring system 28. High-pressure acid fluid or neutral gas enters the high-pressure anti-corrosion hose 9 and passes sequentially through the gas-liquid mixing connector 8, the main pressure sensor 10, the main flow sensor 11, the multiphase flow mixing chamber 12-6, the high-pressure anti-corrosion connector 14, the high-pressure anti-corrosion tubing string 15, the high-pressure anti-corrosion sealer near the wellhead 16, the high-pressure anti-corrosion fracturing tubing string 18, and the high-pressure anti-corrosion sealer near the bottom of the well. When the acid gas fluid pressure exceeds 5MPa after passing through the high-pressure anti-corrosion sealer near the wellhead 16 and the high-pressure anti-corrosion sealer near the bottom of the well, the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing string opens, and the acid or neutral fluid enters the fracturing sealed space. The acid and neutral fluids act on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense fracture network structure.

[0176] SG4. Pumping the solid-gas two-phase mixed fluid. Pump the acid gas fluid for a period of time (3-5 minutes) to reduce the pipeline pressure to 6-8 MPa. Then, open the sand pressure balancing valve 12-1 and slowly adjust the opening of the sand adding valve 12-5 through the main monitoring system, calculating the injection sand ratio based on the sand reduction. Solid particles mix with the high-pressure acid gas fluid in the multiphase flow mixing chamber, forming a solid-gas two-phase fluid. The solid-gas two-phase flow passes through the high-pressure anti-corrosion hose 9, high-pressure anti-corrosion connector 14, high-pressure anti-corrosion tubing string 15, near-hole high-pressure anti-corrosion sealing device 16, high-pressure anti-corrosion fracturing tubing string 18, and near-hole bottom high-pressure anti-corrosion sealing device 17. While passing through the high-pressure anti-corrosion fracturing tubing string, it enters the fracturing sealed space through the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing string, and then enters the acid gas fluid fracturing fracture, further expanding the fracture, forming a dense fracture network, supporting the fracture, reducing fracture aperture changes, and maintaining the high conductivity of the fracture.

[0177] After the interaction between SG5, solid-gas two-phase fluid and rock is completed, the sand pressure balance valve and sand addition valve are closed sequentially through the main monitoring system 28. After 3 minutes, the acid gas outlet valve and acid gas line main outlet valve 1-10 are closed sequentially through the main monitoring system 28. Then, the acid gas fluid high-pressure plunger pump 2 is turned off. After waiting for 3 minutes, the pressure relief valve 13 is slowly opened until the pressure in the pipeline is less than 0.25 MPa, and the fracturing is completed.

[0178] SG6. Move the pipeline to the next fracturing borehole and repeat SG1-SG5 to complete the regional intelligent fracturing operation.

[0179] The entire process of solid-gas two-phase fluid fracturing of rock is controlled by the central monitoring system through the monitoring lines of each device. The array-type acoustic wave monitoring system 20-1 monitors and inverts the crack propagation morphology in real time, providing a basis for the formation of dense cracks. The system also adjusts the parameters of each system through an intelligent system to make the cracks propagate along the required path.

[0180] (5) Intelligent pumping of solid-liquid-gas multiphase mixing

[0181] The equipment involved mainly includes: high-pressure fluid storage system, high-pressure plunger pump for acid gas fluid, outlet valve of acid gas circuit pump, water tank, high-pressure / pulse pump, outlet valve of water circuit pump, gas-liquid mixing connector, high-pressure anti-corrosion hose, main circuit pressure sensor, main circuit flow sensor, high-pressure sand injection system, main circuit pressure relief valve, high-pressure anti-corrosion connector, high-pressure anti-corrosion tubing string, high-pressure anti-corrosion sealing device near the borehole orifice, high-pressure anti-corrosion sealing device near the bottom of the borehole, high-pressure anti-corrosion fracturing tubing string, anti-corrosion high-strength drill bit, rock wall, array-type acoustic monitoring system, multiphase fluid absorber, pumping monitoring system, main monitoring system, and corresponding monitoring lines, etc.

[0182] Includes the following steps:

[0183] SFG1. Drilling. Drilling holes (diameter, angle, length, etc.) into the rock face using a directional drilling rig.

[0184] SFG2, Equipment and Piping Connections. Connect the supercritical CO2 storage tank 1-1, liquid nitrogen storage tank 1-2, and other acidic or neutral fluid storage tanks 1-3 in parallel. Supercritical CO2 storage tank 1-1 is connected to the CO2 outlet valve 1-4 via a high-pressure corrosion-resistant hose. Liquid nitrogen storage tank 1-2 is connected to the liquid nitrogen outlet valve 1-5 via a high-pressure corrosion-resistant hose. Other acidic or neutral fluid storage tanks 1-3 are connected to other fluid outlet valves 1-6 via high-pressure corrosion-resistant hoses. Connect these multiple lines in parallel using a four-way valve. Then, connect the acid gas main outlet valve 1-10, acid gas pressure sensor 1-11, and acid gas flow sensor 1-12 sequentially via high-pressure corrosion-resistant hoses to form a high-pressure fluid storage system. The high-pressure fluid storage system is connected to the acid gas high-pressure plunger pump via a low-pressure corrosion-resistant hose, and the acid gas high-pressure plunger pump is connected to the high-pressure corrosion-resistant hose. A water tank is connected to a high-pressure water pipe in the mine, and a water supply valve is installed on the pipe. The water tank is connected to a high-pressure / pulse pump via a low-pressure hose, and the high-pressure / pulse pump is connected to the water pump outlet valve via a high-pressure corrosion-resistant hose. The water pump outlet valve and the acid gas pump outlet valve are connected to the gas-liquid mixing connector 8 via high-pressure corrosion-resistant hoses, and then connected to high-pressure corrosion-resistant hoses. A main pressure sensor, a main flow sensor, a high-pressure sand injection system, and a main pressure relief valve are then installed on the high-pressure corrosion-resistant hoses. The high-pressure sand injection system consists of a tee on the high-pressure corrosion-resistant hose; one tee connects to the multiphase flow mixing chamber, and the other connects to the sand pressure balancing valve 12-1. The sand pressure balancing valve is connected sequentially to the sand pressure sensor 12-2, the sand flow sensor 12-3, the high-pressure corrosion-resistant sand tank 12-4, and the sand adding valve 12-5 via high-pressure corrosion-resistant hoses. The sand adding valve is connected to the multiphase flow mixing chamber via a high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant sand tank has a sand adding port. High-pressure corrosion-resistant hoses are connected to high-pressure corrosion-resistant tubing strings via high-pressure corrosion-resistant connectors. These tubing strings are then sequentially connected to a near-hole high-pressure corrosion-resistant sealing device, a high-pressure corrosion-resistant fracturing tubing string, a near-hole bottom high-pressure corrosion-resistant sealing device, and a high-strength corrosion-resistant drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock face. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are then connected via a line from the pump monitoring system to the main system monitoring line.

[0185] SFG3, Pumping High-Pressure Acid Gas. After the equipment and pipeline connections are completed, close the main pressure relief valve 13, sand pressure balancing valve 12-1, and sand adding valve 12-5 through the main monitoring system. Open the acid gas pump outlet valve 3, acid gas main outlet valve 1-10, and water pump outlet valve 7. Monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, prepare a spare acid gas storage tank. Monitor the water volume in the water tank. If the water volume is less than 50%, add water to the water tank 5 through the water replenishment valve 4 until the water tank capacity reaches 90%. Monitor and adjust the water volume in the tank throughout the high-pressure water pumping process. In addition, before pumping, observe the sand storage in the high-pressure anti-corrosion sand tank through the main monitoring system. When the sand storage is less than 50%, open the sand adding valve 12-7 through the monitoring system until the sand volume in the sand tank exceeds 90%, then close the sand adding valve 12-7.

[0186] Next, the main monitoring system 28 controls the opening of one of the following acid gas outlet valves: supercritical CO2 outlet valve 1-4, liquid nitrogen outlet valve 1-5, or other fluid outlet valve 1-6, while the other two remain closed. The main monitoring system 28 also controls the start of the high-pressure plunger pump 2, allowing high-pressure acidic fluid or neutral gas to enter the high-pressure anti-corrosion hose 9. Simultaneously, the main monitoring system 28 controls the start of the high-pressure / pulse pump 6, allowing high-pressure water to enter the high-pressure anti-corrosion hose. The gas and liquid are mixed in the gas-liquid mixing connector 8. Then, the gas and liquid two-phase fluid enters the high-pressure anti-corrosion hose and passes sequentially through the tee 8-1, the main pressure sensor 10, the main flow sensor 11, the multiphase flow mixing chamber 12-6, the high-pressure anti-corrosion connector 14, the high-pressure anti-corrosion tubing string 15, the high-pressure anti-corrosion sealer near the wellhead 16, the high-pressure anti-corrosion fracturing tubing string 18, and the high-pressure anti-corrosion sealer near the bottom of the well. When the pressure of the gas and liquid two-phase fluid exceeds 5MPa after passing through the high-pressure anti-corrosion sealer near the wellhead 16 and the high-pressure anti-corrosion sealer near the bottom of the well, the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing string opens, and the gas and liquid two-phase fluid enters the fracturing sealed space. The gas and liquid two-phase fluid acts on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense fracture network structure.

[0187] SFG4, Pumping a Solid-Liquid-Gas Multiphase Mixture. After pumping the gas-liquid two-phase fluid for a period of time (3-5 minutes), reduce the pipeline pressure to 6-8 MPa, then open the sand pressure balancing valve 12-1. Slowly adjust the opening of the sand adding valve 12-5 through the main monitoring system, and calculate the injection sand ratio based on the reduction in sand volume. Solid particles mix with the high-pressure gas-liquid two-phase fluid in the multiphase flow mixing chamber to form a solid-liquid-gas multiphase fluid. The solid-liquid-gas multiphase fluid passes through the high-pressure anti-corrosion hose 9, high-pressure anti-corrosion connector 14, high-pressure anti-corrosion tubing string 15, near-hole high-pressure anti-corrosion sealing device 16, high-pressure anti-corrosion fracturing tubing string 18, and near-hole bottom high-pressure anti-corrosion sealing device 17. When passing through the high-pressure corrosion-resistant fracturing string, it enters the fracturing sealed space through the multiphase flow outlet of the high-pressure corrosion-resistant fracturing string, and then enters the gas-liquid two-phase fluid fracturing fracture, which further expands the fracture, forms a dense fracture network, supports the fracture, reduces the change in fracture aperture, and maintains the high conductivity of the fracture.

[0188] After the interaction of SFG5, solid-liquid-gas multiphase fluid and rock is completed, the sand pressure balance valve and sand addition valve are closed sequentially through the main monitoring system 28. After 3 minutes, the acid gas outlet valve and acid gas line main outlet valve 1-10 are closed sequentially through the main monitoring system 28. Then, the acid gas fluid high-pressure plunger pump 2 and high-pressure / pulse pump 6 are closed. After waiting for 3 minutes, the pressure relief valve 13 is slowly opened until the pressure in the pipeline is less than 0.3 MPa, and the fracturing is completed.

[0189] SFG6: Move the pipeline to the next fracturing borehole and repeat SG1-SG5 to complete the regional intelligent fracturing operation.

[0190] The entire process of rock fracturing using solid-liquid-gas multiphase fluids is controlled by a central monitoring system that monitors and controls the operation of all equipment through the monitoring lines of each device. The array-type acoustic monitoring system 20-1 monitors and inverts the crack propagation morphology in real time, providing a basis for the formation of dense cracks. It also adjusts the parameters of each system through an intelligent system to make the cracks propagate along the required path.

[0191] (6) Intelligent regulation of rock fracture morphology

[0192] Intelligent control of rock fracture morphology primarily employs adjustments to the flow rate, pressure, and frequency of the solid, liquid, and gas phases to control fracture propagation. Methods include using an array-type acoustic monitoring system to monitor fracture propagation in real time and retrieving control parameters based on the monitoring data to achieve the desired fracture morphology.

[0193] 1) Unidirectional crack control to crack network expansion. When monitoring shows that the crack is expanding in a single direction, if only water is injected, the pulsation frequency of the water injection should be increased. Through the pulsating effect of the water flow, fatigue damage should be formed on the crack surface, thereby breaking the control of the ground stress and forming microcracks on the inner wall of the crack. After the microcracks are formed, observe the cracks to start expanding. When the amplitude of the expansion length change decreases, reduce the water injection frequency and increase the discharge rate. Use high discharge rate to impact the microcracks, causing the microcracks to expand and form a crack network. If the effect is still not good, the frequency can be adjusted multiple times to allow the crack network to fully develop.

[0194] 2) Crack network control for unidirectional crack propagation. When monitoring and inversion show that crack propagation has become a multidirectional crack network, such as by injecting only water, gradually reduce the fluid pressure and frequency. Observe that the crack direction gradually changes from multidirectional to unidirectional. By reducing the water pressure and flow rate range, the cracks are made to propagate only along the direction most likely to propagate. Then, adjust and maintain the crack propagation direction.

[0195] 3) Fracture Network Boundary Control Methods. ① If it is necessary to control fractures from intersecting, and only through seepage migration (e.g., in leaching mining of metal mines), when the distance between the fracture network and the previous fracture network is 1m, reduce the fluid pressure and flow rate to stop the fractures from extending further. Increase the number of fractures within the existing fracture network only through low-volume, high-frequency pulsation. A small amount of solid can also be added to block micro-fractures, reduce fracture filtration efficiency, and improve the overall permeability of the area, thereby increasing production. ② When it is necessary to control fracture intersections and make the fracture network continuous (e.g., in conventional and unconventional oil and gas extraction), after the fracture network is continuous, the fluid pressure does not need to overcome the tensile strength of the rock, thus gradually decreasing, causing fracture expansion to slow down or even stop. At this time, there are fewer fractures at the fracture network boundary. In this case, it is necessary to increase the pulsation frequency and flow rate so that the fluid loss is less than the injection volume, thereby promoting the expansion of the fracture network at the boundary, improving the permeability of the two borehole sections, and thus improving the conductivity of the fracture network. If the crack network monitoring based on acoustic signals is still not ideal, the proportion of solids (sand) in the fluid can be increased. By blocking the microcrack channels with solids, fluid loss can be reduced and fluid resistance increased, thereby allowing the crack network to develop more fully.

[0196] 4) Initial weakening of the fracture network. In the early stage of fracture propagation, in order to make the fractures propagate evenly in multiple directions, acidic fluid can be injected into the fractures for a period of time to weaken the rock layer and reduce the rock layer strength. Through the phase change of the gas, a relatively dense fracture network is formed in the closed section. Then, high-volume fracturing combined with sand addition is used to achieve the goal of fully developing the fracture network.

[0197] (7) Multiphase separation and recovery system

[0198] The equipment involved mainly includes: multiphase fluid absorbers, multiphase fluid transport pipelines, multiphase fluid separators, mixed gas pipelines, gas liquefaction and separation systems, liquefied gas storage tanks, pump monitoring systems, main monitoring systems, acid gas fluid storage tanks, and corresponding monitoring lines, etc.

[0199] When acidic fluid is injected into a borehole, if the gas escapes from the borehole, it will increase the concentration of CO2, N2, and other gases around the borehole. This can cause breathing difficulties for personnel working in the area. Therefore, it is necessary to recover the gas flowing out or seeping from the borehole. For acidic gases, at the borehole opening, some gas is first absorbed by an acidic gas absorption plate. The remaining gas and solid-liquid multiphase fluid enter the multiphase fluid transport pipeline and reach the multiphase fluid separator. In the separator, solids settle at the bottom, followed by liquids, and then gases. A solid-liquid discharge valve is installed at the bottom of the multiphase fluid separator. When the main monitoring system detects that the liquid level in the separator reaches 70% of the total separator volume, the lower solid-liquid discharge valve is opened to discharge the solid-liquid fluid. When the liquid level reaches 10% of the total separator volume, the lower solid-liquid discharge valve is closed. A gas pipeline is connected to the top of the multiphase fluid separator to deliver the gas to the gas liquefaction and separation system. The gas liquefaction and separation system then separates the multiple components in the mixed gas, such as CO2, CH4, and N2. The liquefied gas or supercritical gas is then stored in the corresponding liquefied gas storage tank. Finally, the liquefied gas or supercritical gas in the liquefied gas storage tank is poured into the acid gas fluid storage tank for recycling.

[0200] (8) CCUS Intelligent Monitoring and Analysis

[0201] The equipment involved mainly includes: high-pressure fluid storage system, rock wall, multiphase fluid absorber, gas liquefaction separation system, liquefied gas storage tank, main monitoring system and corresponding monitoring lines, etc.

[0202] CCUS stands for Carbon Capture, Utilization, and Storage. It involves collecting CO2 emitted in large quantities from the air or other industrial sources, forming a supercritical CO2 fluid, and then injecting this fluid into the formation. The CO2 reacts with the rock formation, solidifying it and weakening the rock, increasing the density of the fracture network, thus facilitating the extraction of oil, gas, or metal mines. CO2 not fully absorbed at the formation wall is stored using multiphase fluid absorbers, gas liquefaction separation systems, and liquefied gas storage tanks. CH4 from the reservoir is also stored and collected, reducing carbon emissions, increasing carbon utilization, and contributing to mitigating the greenhouse effect.

[0203] During CCUS intelligent monitoring and analysis, the carbon content change (Q1, mainly CO2) in the high-pressure fluid storage system is monitored through the overall monitoring system; the absorption amount (Q2) of the multiphase fluid absorber is monitored through the absorber monitoring line; and the CO2 content (Q3) and other carbon contents (Q4) separated from the mixed gas are monitored through the gas liquefaction and separation system monitoring line. The carbon sequestration capacity, capture capacity, and utilization rate are calculated, with the carbon sequestration capacity being Q. C =Q1-Q2-Q3, carbon capture amount is Q B =Q2+Q4, carbon utilization rate is Q L =1-(Q2+Q3) / Q1.

[0204] Example 1

[0205] A CO2 pre-fracturing and permeability enhancement (CCUS) device for underground mines includes a high-pressure fluid storage system 1, a high-pressure plunger pump for acid gas fluid 2, an acid gas pump outlet valve 3, a water supply valve 4, a water tank 5, a high-pressure / pulse pump 6, a water pump outlet valve 7, a gas-liquid mixing connector 8, a tee 8-1, a high-pressure corrosion-resistant hose 9, a main pressure sensor 10, a main flow sensor 11, a high-pressure sand injection system 12, a main pressure relief valve 13, a high-pressure corrosion-resistant connector 14, a high-pressure corrosion-resistant tubing string 15, a high-pressure corrosion-resistant sealing device near the borehole opening 16, a high-pressure corrosion-resistant sealing device near the bottom of the borehole 17, a high-pressure corrosion-resistant fracturing tubing string 18, a corrosion-resistant high-strength drill bit 19, a rock wall 20, a multiphase fluid absorber 21, a multiphase fluid transport pipeline 22, a multiphase fluid separator 23, a mixed gas pipeline 24, a gas liquefaction separation system 25, a liquefied gas storage tank 26, a pumping monitoring system 27, and a main monitoring system 28.

[0206] The high-pressure fluid storage system 1 includes: a supercritical CO2 storage tank 1-1, a liquid nitrogen storage tank 1-2, other acidic or neutral fluid storage tanks (e.g., low-concentration hydrochloric acid, sulfuric acid, etc.) 1-3, a CO2 outlet valve 1-4, a liquid nitrogen outlet valve 1-5, other fluid outlet valves 1-6, a CO2 outlet valve monitoring line 1-7, a liquid nitrogen outlet valve monitoring line 1-8, other fluid outlet valve monitoring lines 1-9, a total acid gas outlet valve 1-10, an acid gas pressure sensor 1-11, an acid gas flow sensor 1-12, a total acid gas outlet valve monitoring line 1-13, an acid gas pressure sensor monitoring line 1-14, and an acid gas flow sensor monitoring line 1-15.

[0207] The acid gas high-pressure plunger pump 2 is connected to the pumping monitoring system 27 via acid gas high-pressure plunger pump monitoring line 2-1 to monitor the start and stop of the acid gas high-pressure plunger pump 2. The acid gas pump outlet valve 3 is connected to the pumping monitoring system 27 via acid gas pump outlet valve monitoring line 3-1 to monitor the on / off status of the acid gas pump outlet valve 3. The water supply valve 4 is connected to the pumping monitoring system 27 via water supply valve monitoring line 4-1 to monitor the opening degree of the water supply valve 4. The water tank 5 is connected to the pumping monitoring system 27 via water tank level monitoring line 5-1 to monitor changes in the water level in the water tank 4. The high-pressure / pulse pump 6 is connected to the pumping monitoring system 27 via high-pressure / pulse pump monitoring line 6-1 to monitor the start and stop of the high-pressure / pulse pump 6. The water pump outlet valve 7 is connected to the pumping monitoring system 27 via water pump outlet valve monitoring line 7-1 to monitor the on / off status of the water pump outlet valve 7.

[0208] The high-pressure sand injection system 12 includes a sand pressure balancing valve 12-1, a sand pressure sensor 12-2, a sand flow sensor 12-3, a high-pressure corrosion-resistant sand tank 12-4, a sand adding valve 12-5, a multiphase flow mixing chamber 12-6, a sand adding port 12-7, a sand pressure balancing valve monitoring line 12-8, a sand pressure sensor detection line 12-9, a sand flow sensor monitoring line 12-10, a sand adding valve monitoring line 12-11, a sand quantity monitoring line 12-12, and a sand adding port monitoring line 12-13. The sand pressure balancing valve 12-1 is connected to the main monitoring system 28 via the sand pressure balancing valve 12-8 monitoring line to monitor the on / off status of the sand pressure balancing valve 12-1. The sand pressure sensor 12-2 is connected to the main monitoring system 28 via the sand pressure sensor detection line 12-9 to monitor the sand pressure. The sand flow sensor 12-3 is connected to the main monitoring system 28 via sand flow sensor monitoring line 12-10 to monitor the sand flow rate. The sand filling valve 12-5 is connected to the main monitoring system 28 via sand filling valve monitoring line 12-11 to monitor the opening degree of the sand filling valve 12-5. The high-pressure corrosion-resistant sand tank 12-4 is connected to the main monitoring system 28 via sand quantity monitoring line 12-12 to monitor the sand quantity inside the sand tank 12-4. The sand filling port 12-7 is connected to the main monitoring system 28 via sand filling port monitoring line 12-13 to monitor the opening degree of the sand filling port 12-7.

[0209] The main pressure relief valve 13 is connected to the main monitoring system 28 via the main pressure relief valve monitoring line 13-1 to monitor the valve's on / off status. The high-pressure corrosion-resistant fracturing string 18 is equipped with a multiphase flow outlet 18-1 for passing a multiphase mixture of solid, liquid, and gaseous fluids. An array-type acoustic monitoring system 20-1 is installed inside the rock wall 20 and connected to the main monitoring system 28 via the array-type acoustic monitoring system monitoring line 20-2 to analyze the rock fracture status in real time. The multiphase fluid absorber 21 contains an acid gas absorption plate 21-1 to absorb acid gases such as CO2, and is connected to the main monitoring system 28 via the absorber monitoring line 21-2 to monitor information such as the flow rate of each phase of the multiphase fluid passing through the absorber. The gas liquefaction separation system 25 is connected to the main monitoring system 28 via the gas liquefaction separation system monitoring line 25-1 to monitor gas composition and flow rate. The liquefied gas storage tank 26 is connected to the main monitoring system 28 via the liquefied gas storage tank monitoring line 26-1 to monitor the remaining liquefied gas level.

[0210] The pumping monitoring system 27 mainly consists of three modules: the acid gas path monitoring system 27-1, the water path monitoring system 27-2, and the fault alarm system 27-3. The main monitoring system 28 can observe the status of the pumping monitoring system 27 and control its operation through the main system monitoring line 27-4.

[0211] The overall monitoring system 28 includes the overall acid gas path monitoring system 28-1, the overall water path monitoring system 28-2, the overall sand path monitoring system 28-3, the CCUS analysis system 28-4, the rock stratum fracture status monitoring system 28-5, the safety monitoring system 28-6, and the effect analysis system 28-7.

[0212] Example 2

[0213] A method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS intelligent control in underground mines includes the following steps:

[0214] Step 1, Drilling. A directional drilling rig is used to drill holes of the required dimensions (diameter, angle, length, etc.) into the rock face at a depth of 20 mm.

[0215] Step 2, Equipment and Piping Connection. Connect the supercritical CO2 storage tank 1-1, liquid nitrogen storage tank 1-2, and other acidic or neutral fluid storage tanks 1-3 in parallel. Supercritical CO2 storage tank 1-1 is connected to the CO2 outlet valve 1-4 via a high-pressure corrosion-resistant hose. Liquid nitrogen storage tank 1-2 is connected to the liquid nitrogen outlet valve 1-5 via a high-pressure corrosion-resistant hose. Other acidic or neutral fluid storage tanks 1-3 are connected to other fluid outlet valves 1-6 via high-pressure corrosion-resistant hoses. Connect the multiple lines in parallel using a four-way valve. Then, connect the acid gas main outlet valve 1-10, acid gas pressure sensor 1-11, and acid gas flow sensor 1-12 sequentially via high-pressure corrosion-resistant hoses to form a high-pressure fluid storage system 1. The high-pressure fluid storage system is connected to the acid gas high-pressure plunger pump 2 via a low-pressure corrosion-resistant hose. The acid gas high-pressure plunger pump 2 is connected to a high-pressure corrosion-resistant hose 9. Connect water tank 5 to the high-pressure water pipe in the mine, and install a water supply valve 4 on the pipe. The water tank is connected to the high-pressure / pulse pump 6 via a low-pressure hose. The high-pressure / pulse pump 6 is connected to the water pump outlet valve 7 via a high-pressure anti-corrosion hose 9. The water pump outlet valve 7 and the acid gas pump outlet valve 3 are connected to the gas-liquid mixing connector 8 via the high-pressure anti-corrosion hose 9, and then connected to the high-pressure anti-corrosion hose 9. Then, install a main pressure sensor 10, a main flow sensor 11, a high-pressure sand injection system 12, and a main pressure relief valve 13 on the high-pressure anti-corrosion hose 9. The high-pressure sand injection system 12 has a tee 8-1 on the high-pressure corrosion-resistant hose 9. One tee connects to the multiphase flow mixing chamber 12-6, and the other connects to the sand path pressure balancing valve 12-1. The sand path pressure balancing valve 12-1 is connected in sequence to the sand path pressure sensor 12-2, the sand path flow sensor 12-3, the high-pressure corrosion-resistant sand tank 12-4, and the sand adding valve 12-5 via the high-pressure corrosion-resistant hose 9. The sand adding valve 12-5 is connected to the multiphase flow mixing chamber 12-6 via the high-pressure corrosion-resistant hose 9. The high-pressure corrosion-resistant sand tank 12-4 is equipped with a sand adding port 12-7. The high-pressure corrosion-resistant hose 9 is connected to the high-pressure corrosion-resistant tubing string 15 via the high-pressure corrosion-resistant connector 14. The high-pressure corrosion-resistant tubing string 15 is connected in sequence to the high-pressure corrosion-resistant sealing device 16 near the borehole opening, the high-pressure corrosion-resistant fracturing tubing string 18, the high-pressure corrosion-resistant sealing device 17 near the bottom of the borehole, and the corrosion-resistant high-strength drill bit 19. A multiphase fluid absorber 21 is installed at the borehole opening. At the same time, an array-type acoustic monitoring system 20-1 is installed on the rock wall, and then all relevant equipment is connected to the pumping monitoring system 27 and the main monitoring system 28 through corresponding monitoring or monitoring lines, and the two systems are connected to the main system monitoring line 27-4 through the pumping monitoring system.

[0216] Step 3: Pumping high-pressure liquid. After the equipment and pipeline connections are completed, monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank must be prepared. Monitor the water volume in the water tank. If the water volume is less than 50%, add water to the water tank 5 by controlling the water supply valve 4 until the water tank capacity reaches 90%. Monitor and adjust the water volume in the tank throughout the high-pressure water pumping process. In addition, before pumping, observe the sand storage in the high-pressure anti-corrosion sand tank through the main monitoring system. When the sand storage is less than 50%, control the sand adding valve 12-7 to open through the monitoring system until the sand volume in the sand tank exceeds 90%, then close the sand adding valve 12-7. The above solid-liquid-gas content is monitored throughout the entire process through the main monitoring system 28. Close the main line pressure relief valve 13, sand line pressure balance valve 12-1, sand adding valve 12-5, and acid gas line pump outlet valve 3 through the main monitoring system 28, and open the water line pump outlet valve 7. Next, the high-pressure / pulse pump 6 is started via the main monitoring system 28. High-pressure water enters the high-pressure anti-corrosion hose and passes sequentially through the gas-liquid mixing connector 8, the main pressure sensor 10, the main flow sensor 11, the multiphase flow mixing chamber 12-6, the high-pressure anti-corrosion connector 14, the high-pressure anti-corrosion tubing string 15, the near-hole high-pressure anti-corrosion sealer 16, the high-pressure anti-corrosion fracturing tubing string 18, and the near-hole bottom high-pressure anti-corrosion sealer 17. After passing through the near-hole high-pressure anti-corrosion sealer 16 and the near-hole bottom high-pressure anti-corrosion sealer 17, the water flows through the high-pressure anti-corrosion sealer 16 and the near-hole bottom high-pressure anti-corrosion sealer 17. When the water pressure does not exceed the pressure (5MPa) of the multiphase flow outlet 18-1 of the high-pressure anti-corrosion fracturing string, the capsules of the high-pressure anti-corrosion sealing device 16 near the borehole orifice and the high-pressure anti-corrosion sealing device 17 near the bottom of the borehole are opened and attached to the rock wall 20 to form a fracturing sealed space. When the water pressure exceeds 5MPa, the multiphase flow outlet of the high-pressure anti-corrosion fracturing string opens and high-pressure water enters the fracturing sealed space. The water pressure acts on the rock wall. When the rock reaches the critical fracturing pressure, the rock fractures and forms a hydraulic fracture.

[0217] Step 4: Pump in high-pressure acid gas fluid to weaken the water pressure fracturing. After high-pressure water fracturing for 5-10 minutes, reduce the water pressure to 6-8 MPa. Then, through the main monitoring system 28, close the main pressure relief valve 13, sand pressure balancing valve 12-1, and sand adding valve 12-5, and open the acid gas pump outlet valve 3, the acid gas main outlet valve 1-10, and the water pump outlet valve 7. Next, through the main monitoring system 28, control the opening of the supercritical CO2 outlet valve 1-4 and close the liquid nitrogen outlet valve 1-5 or other fluid outlet valves 1-6. Through the main monitoring system 28, control the start of the high-pressure plunger pump 2 for acid gas fluid, allowing high-pressure acid fluid or neutral gas to enter the high-pressure anti-corrosion hose 9. Simultaneously, through the main monitoring system 28, control the start of the high-pressure / pulse pump 6, allowing high-pressure water to enter the high-pressure anti-corrosion hose. The gas and liquid are mixed in the gas-liquid mixing connector 8. Then, the gas and liquid two-phase fluid enters the high-pressure anti-corrosion hose and passes sequentially through the tee 8-1, the main pressure sensor 10, the main flow sensor 11, the multiphase flow mixing chamber 12-6, the high-pressure anti-corrosion connector 14, the high-pressure anti-corrosion tubing string 15, the high-pressure anti-corrosion sealer near the wellhead 16, the high-pressure anti-corrosion fracturing tubing string 18, and the high-pressure anti-corrosion sealer near the bottom of the well. When passing through the high-pressure anti-corrosion sealer near the wellhead 16 and the high-pressure anti-corrosion sealer near the bottom of the well, the gas and liquid two-phase fluid enters the fracturing sealed space. The gas and liquid two-phase fluid acts on the rock wall 20, softening the rock wall and causing the cracks to expand again, forming a weakened structure of the wall fracture network.

[0218] Step 5: Pumping the solid-liquid-gas multiphase mixture. After pumping the gas-liquid two-phase fluid for a period of time (5-10 minutes), reduce the pipeline pressure to 6-8 MPa, then open the sand pressure balancing valve 12-1. Slowly adjust the opening of the sand adding valve 12-5 through the main monitoring system, and calculate the injection sand ratio based on the sand reduction. Solid particles and the high-pressure gas-liquid two-phase fluid mix in the multiphase flow mixing chamber to form a solid-liquid-gas multiphase fluid. The solid-liquid-gas multiphase fluid passes through the high-pressure anti-corrosion hose 9, high-pressure anti-corrosion connector 14, high-pressure anti-corrosion tubing string 15, near-hole high-pressure anti-corrosion sealing device 16, high-pressure anti-corrosion fracturing tubing string 18, and near-hole bottom high-pressure anti-corrosion sealing device 17. When passing through the high-pressure corrosion-resistant fracturing string 18, it enters the fracturing sealed space through the multiphase flow outlet 18-1 of the high-pressure corrosion-resistant fracturing string, and then enters the gas-liquid two-phase fluid fracturing fracture, which further expands the fracture, forms a dense fracture network, supports the fracture, reduces the change in fracture opening, and maintains the high conductivity of the fracture.

[0219] Step 6: After the solid-liquid-gas multiphase fluid interacts with the rock, the sand pressure balance valve and sand addition valve are closed sequentially through the main monitoring system 28. After 3 minutes, the acid gas outlet valve and the acid gas main outlet valve 1-10 are closed sequentially through the main monitoring system 28. Then, the acid gas fluid high-pressure plunger pump 2 and high-pressure / pulse pump 6 are turned off. After waiting for 3 minutes, the pressure relief valve 13 is slowly opened until the pressure in the pipeline is less than 0.3 MPa, and the fracturing is completed.

[0220] Step 7: Move the pipeline to the next fracturing borehole and repeat steps 1-6 to complete the regional intelligent fracturing operation.

[0221] The entire process of rock fracturing using solid-liquid-gas multiphase fluids is controlled by a central monitoring system that monitors and controls the operation of all equipment through the monitoring lines of each device. The array-type acoustic wave monitoring system 20-1 monitors and inverts the crack propagation morphology in real time, providing a basis for the formation of dense cracks, and adjusts the parameters of each system through an intelligent system to make the cracks propagate along the required path. The entire construction process is monitored and intelligently analyzed by CCUS data and feedback is provided.

Claims

1. A coal mine carbon dioxide pre-fracturing and sand injection permeability enhancement (CCUS) device, characterized in that, include: A high-pressure pumping system is used to pump fluid into the formation. The system includes a high-pressure fluid storage system and a pumping monitoring system. The high-pressure fluid storage system stores supercritical CO2, liquid nitrogen, and other acidic or neutral fluids, including a backup of supercritical CO2 gas. The pumping monitoring system monitors relevant parameters and equipment operating status in the acid gas path and water path, and provides equipment fault alarms. The high-pressure pumping system also includes an acid gas fluid high-pressure plunger pump, an acid gas path pump outlet valve, a water tank, a high-pressure / pulse pump, a water path pump outlet valve, and a gas-liquid mixing connector. One end of the high-pressure / pulse pump is connected to the water tank, and the other end is connected to the water path pump outlet valve. One end of the acid gas fluid high-pressure plunger pump is connected to the high-pressure fluid storage system, and the other end is connected to the acid gas path pump outlet valve. The other end of the acid gas path pump outlet valve is connected to the gas-liquid mixing connector. The acid gas fluid high-pressure plunger pump, high-pressure / pulse pump, water pump outlet valve, acid gas pump outlet valve are electrically connected to the pumping monitoring system; The high-pressure sand injection system is used to store solid particles as proppant, adjust the sand path pressure and flow rate, and control the amount of sand added, so that the proppant and fluid are mixed in the multiphase flow mixing chamber; the gas-liquid mixing connector is connected to the high-pressure sand injection system through a high-pressure corrosion-resistant hose; An array-type acoustic monitoring system is installed inside the rock wall to analyze the state of rock fractures in real time. A gas liquefaction and separation system is used to separate gas components from a mixed gas transported by a multiphase fluid separator and to liquefy the separated gas. The overall monitoring system is used to monitor the parameters of each system, control the operation of each device, analyze the state of rock fractures and CCUS effects, and achieve full-process control. It also includes a liquefied gas storage tank, a tee, a high-pressure corrosion-resistant connector, a high-pressure corrosion-resistant tubing string, a near-hole high-pressure corrosion-resistant sealer, a near-hole bottom high-pressure corrosion-resistant sealer, a high-pressure corrosion-resistant fracturing tubing string, a corrosion-resistant high-strength drill bit, a multiphase fluid absorber, and a multiphase fluid separator; the corrosion-resistant high-strength drill bit, the high-pressure corrosion-resistant fracturing tubing string, and the high-pressure corrosion-resistant tubing string are connected sequentially; the high-pressure corrosion-resistant connector is installed on the high-pressure corrosion-resistant tubing string; the high-pressure corrosion-resistant tubing string is connected to the high-pressure sand injection system; the near-hole bottom high-pressure corrosion-resistant sealer and the near-hole top high-pressure corrosion-resistant sealer are sleeved on the high-pressure corrosion-resistant fracturing tubing string, and the multiphase fluid absorber is installed on the high-pressure corrosion-resistant tubing string; the multiphase fluid absorber and the multiphase fluid separator are connected through a multiphase fluid transport pipeline; the multiphase fluid separator is connected to the gas liquefaction and separation system through a mixed gas pipeline; the liquefied gas storage tank is connected to the high-pressure fluid storage system. Between the gas liquefaction and separation system; one end of the tee is connected to the gas-liquid mixing connector via a high-pressure anti-corrosion hose, and the other end is connected to the high-pressure sand injection system via a high-pressure anti-corrosion hose; the liquefied gas storage tank and the multiphase fluid separator are electrically connected to the main monitoring system; the multiphase fluid absorber includes an absorber tube wall and an acid gas absorber plate; the acid gas absorber plate is installed inside the absorber tube wall; the acid gas absorber plate is provided with a circular hole to accommodate the passage of the high-pressure anti-corrosion tubing; a solid-liquid flow channel is provided inside the absorber tube wall; the high-pressure sand injection system includes a sand path pressure balance valve, a sand path pressure sensor, a sand path flow sensor, a high-pressure anti-corrosion sand tank, a sand adding valve, and a multiphase flow mixing chamber; the high-pressure anti-corrosion sand tank is provided with a sand adding port; the lower end of the high-pressure anti-corrosion sand tank is connected to the multiphase flow mixing chamber; the sand adding valve is installed on the pipeline between the high-pressure anti-corrosion sand tank and the multiphase flow mixing chamber; The multiphase flow mixing chamber is connected between the high-pressure corrosion-resistant connector and the tee; one end of the sand pressure balancing valve is connected to the pipeline between the multiphase flow mixing chamber and the tee, and the other end is connected to the upper end of the high-pressure corrosion-resistant sand tank; the sand pressure sensor and the sand flow sensor are connected to the pipeline between the sand pressure balancing valve and the high-pressure corrosion-resistant sand tank; the sand pressure balancing valve, the sand pressure sensor, the sand flow sensor, and the sand adding valve are electrically connected to the main monitoring system.

2. The underground carbon dioxide pre-fracturing and sand injection permeability enhancement equipment (CCUS) as described in claim 1, characterized in that, The high-pressure fluid storage system includes a supercritical CO2 storage tank, a liquid nitrogen storage tank, other acidic or neutral fluid storage tanks, a CO2 outlet valve, a liquid nitrogen outlet valve, other fluid outlet valves, a total acid gas outlet valve, an acid gas pressure sensor, and an acid gas flow sensor. One end of the total acid gas outlet valve is connected to the high-pressure acid gas plunger pump, and the other end is connected to the supercritical CO2 storage tank, the liquid nitrogen storage tank, and the other acidic or neutral fluid storage tanks. The CO2 outlet valve is installed on the pipeline between the supercritical CO2 storage tank and the total acid gas outlet valve. The liquid nitrogen outlet valve is installed on the pipeline between the liquid nitrogen storage tank and the main outlet valve of the acid gas circuit; Other fluid outlet valves are installed on the pipeline between other acidic or neutral fluid storage tanks and the main outlet valve of the acid gas path; acid gas path pressure sensor and acid gas path flow sensor are installed on the pipeline between the main outlet valve of the acid gas path and the high-pressure plunger pump of acid gas fluid; CO2 outlet valve, liquid nitrogen outlet valve, other fluid outlet valves, main outlet valve of the acid gas path, acid gas path pressure sensor, and acid gas path flow sensor are electrically connected to the pumping monitoring system.

3. The underground carbon dioxide pre-fracturing and sand injection permeability enhancement equipment (CCUS) as described in claim 1, characterized in that, The pumping monitoring system includes an acid gas path monitoring system, a water path monitoring system, and a fault alarm system.

4. The underground carbon dioxide pre-fracturing and sand injection permeability enhancement equipment (CCUS) as described in claim 1, characterized in that, The overall monitoring system includes an overall acid gas path monitoring system, an overall water path monitoring system, an overall sand path monitoring system, a CCUS analysis system, a rock fracture status monitoring system, a safety monitoring system, and an effect analysis system.

5. The underground carbon dioxide pre-fracturing and sand injection permeability enhancement equipment as described in claim 1, characterized in that, A water supply valve is installed on the water tank; the water supply valve is electrically connected to the pumping monitoring system; a main pressure sensor is installed on the tee; a main flow sensor is installed on the pipeline between the tee and the high-pressure sand injection system; the main pressure sensor and the main flow sensor are electrically connected to the main monitoring system.

6. The underground carbon dioxide pre-fracturing and sand injection permeability enhancement equipment (CCUS) as described in claim 1, characterized in that, A main pressure relief valve is installed on the pipeline between the high-pressure sand injection system and the high-pressure corrosion-resistant connector; the main pressure relief valve is electrically connected to the main monitoring system.

7. A method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS in underground mines, based on the pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS equipment described in claim 1, characterized in that... Includes the following steps: Step 1: Drill holes in the rock face using a directional drilling rig; Step 2: Connect the high-pressure fluid storage system, high-pressure sand injection system, gas liquefaction and separation system, array-type acoustic monitoring system, pump injection monitoring system, and overall monitoring system; Step 3: Under the overall control of the monitoring system, one or more fluids are pumped into the borehole, and the state of rock fractures is monitored in real time through an array-type acoustic monitoring system, and the fracture propagation morphology is intelligently controlled. Step 4: Absorb, separate multiphase fluids and recover CO2 after fracturing; Step 5: Simultaneously, the monitoring system monitors and analyzes the carbon sequestration amount, capture amount, and utilization rate to achieve integrated operation of underground fracturing and permeability enhancement with carbon capture, utilization, and sequestration.

8. The method for pre-fracturing and sand injection for enhanced permeability and CCUS intelligent control in underground mines as described in claim 7, characterized in that, Step 3 employs a high-pressure water intelligent pumping method, specifically including: F1. Equipment and Piping Connections: Connect the water tank to the high-pressure water pipe in the mine and install a water supply valve on the pipe. Connect the water tank to the high-pressure / pulse pump via a low-pressure hose. Connect the high-pressure / pulse pump to the water pump outlet valve via a high-pressure corrosion-resistant hose. Install a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a main pressure relief valve, a tee, and a multiphase flow mixing chamber on the high-pressure corrosion-resistant hose. Connect the high-pressure corrosion-resistant hose to the high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is sequentially connected to a high-pressure corrosion-resistant sealing device near the borehole opening, a high-pressure corrosion-resistant fracturing tubing string, a high-pressure corrosion-resistant sealing device near the bottom of the borehole, and a corrosion-resistant high-strength drill bit. Install a multiphase fluid absorber at the borehole opening. Simultaneously, install an array-type acoustic monitoring system on the rock wall. Then connect all relevant equipment to the pump monitoring system and the main monitoring system via corresponding monitoring or monitoring lines. Connect the two systems via the monitoring line from the pump monitoring system to the main system. F2. Pumping high-pressure liquid: Close the main pressure relief valve, sand circuit pressure balance valve, sand adding valve, and acid gas circuit pump outlet valve through the main monitoring system, and open the water circuit pump outlet valve. Monitor the water level in the tank. If the water level is less than 50%, add water to the tank through the water replenishment valve until the tank capacity reaches 90%. Monitor and adjust the water level in the tank throughout the high-pressure water pumping process. Then, start the high-pressure / pulse pump through the main monitoring system. High-pressure water enters the high-pressure anti-corrosion hose and passes sequentially through the gas-liquid mixing connector, main pressure sensor, main flow sensor, multiphase flow mixing chamber, high-pressure anti-corrosion connector, high-pressure anti-corrosion tubing string, and near-orifice high-pressure anti-corrosion hose. Corrosion-resistant fracturing tubing, high-pressure corrosion-resistant fracturing string, and near-bottom high-pressure corrosion-resistant sealer; when passing near-orifice and near-bottom high-pressure corrosion-resistant sealers, during the period when the water pressure does not exceed 5 MPa at the multiphase flow outlet pressure of the high-pressure corrosion-resistant fracturing tubing, the capsules of the near-orifice and near-bottom high-pressure corrosion-resistant sealers are opened and adhered to the rock wall, forming a fracturing sealed space; when the water pressure exceeds 5 MPa, the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing opens, high-pressure water enters the fracturing sealed space, and the water pressure acts on the rock wall. When the rock reaches the critical fracturing pressure, the rock fractures, forming hydraulic fractures; F3. After the high-pressure water and rock have interacted, the high-pressure / pulse pump is shut down through the main monitoring system, and then the pressure relief valve is opened until the pressure in the pipeline is less than 0.2 MPa, at which point the fracturing is complete. F4. Move the pipeline to the next fracturing borehole and repeat F1 to F3 to complete the regional intelligent fracturing operation.

9. The method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS intelligent control in underground mines as described in claim 8, characterized in that, Throughout the entire process of implementing the high-pressure water intelligent pump injection method, the operation of all equipment is controlled by the central monitoring system. The array-type acoustic monitoring system monitors and inverts the crack propagation morphology in real time, and adjusts the parameters of each system to make the cracks propagate along the required path.

10. The method for pre-fracturing and sand injection for enhanced permeability and CCUS intelligent control in underground mines as described in claim 7, characterized in that, Step 3 employs a high-pressure liquefied gas intelligent pump injection method, specifically including: G1. Equipment and Piping Connections: Connect the supercritical CO2 storage tank, liquid nitrogen storage tank, and other acidic or neutral fluid storage tanks in parallel. The supercritical CO2 storage tank is connected to the CO2 outlet valve via a high-pressure corrosion-resistant hose. The liquid nitrogen storage tank is connected to the liquid nitrogen outlet valve via a high-pressure corrosion-resistant hose. The other acidic or neutral fluid storage tanks are connected to the outlet valves of other fluids via high-pressure corrosion-resistant hoses. Connect the multiple lines in parallel via a four-way valve. Connect the acid gas line main outlet valve, acid gas line pressure sensor, and acid gas line flow sensor sequentially via high-pressure corrosion-resistant hoses to form a high-pressure fluid storage system. The high-pressure fluid storage system is connected to the acid gas fluid high-pressure plunger pump via a low-pressure corrosion-resistant hose. The acid gas fluid high-pressure plunger pump is connected to the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a main pressure relief valve, and a multiphase flow mixing chamber. The high-pressure corrosion-resistant hose is connected to a high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is sequentially connected to a near-hole high-pressure corrosion-resistant sealing device, a high-pressure corrosion-resistant fracturing tubing string, a near-hole bottom high-pressure corrosion-resistant sealing device, and a corrosion-resistant high-strength drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock wall. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are connected via a monitoring line from the pump monitoring system to the main system. G2. Pump in high-pressure acid gas fluid; close the main pressure relief valve, sand pressure balance valve, sand adding valve, and water pump outlet valve through the main monitoring system, and open the acid gas pump outlet valve and the main acid gas outlet valve; monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank should be prepared; then, control the opening of one of the supercritical CO2 outlet valve, liquid nitrogen outlet valve, or other fluid outlet valves through the main monitoring system, while keeping the other two closed; control the start of the high-pressure plunger pump for acid gas fluid through the main monitoring system, and the high-pressure acid fluid or neutral gas enters the high-pressure anti-corrosion system. The etching tubing sequentially passes through a tee, a main pressure sensor, a main flow sensor, a multiphase flow mixing chamber, a high-pressure corrosion-resistant connector, a high-pressure corrosion-resistant tubing string, a near-orifice high-pressure corrosion-resistant sealer, a high-pressure corrosion-resistant fracturing tubing string, and a near-bottom high-pressure corrosion-resistant sealer. When passing the near-orifice and near-bottom high-pressure corrosion-resistant sealers, if the acid gas fluid pressure exceeds 5 MPa, the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing string opens, allowing acidic or neutral fluid to enter the fracturing confined space. The acidic and neutral fluids act on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense network of fractures. G3. After the interaction between the acid gas fluid and the rock is completed, the acid gas outlet valve and the main outlet valve of the acid gas line are closed sequentially through the main monitoring system. Then, the high-pressure plunger pump of the acid gas fluid is turned off. After waiting for 3 minutes, the pressure relief valve is slowly opened until the pressure in the pipeline is less than 0.15 MPa, and the fracturing is completed. G4. Move the pipeline to the next fracturing borehole and repeat G1 to G3 to complete the regional intelligent fracturing operation.

11. The method for pre-fracturing and sand injection for enhanced permeability and CCUS intelligent control in underground mines as described in claim 10, characterized in that, Throughout the entire process of implementing the high-pressure liquefied gas intelligent pump injection method, the operation of all equipment is controlled by the central monitoring system. The array-type acoustic monitoring system monitors and inverts the crack propagation morphology in real time, and adjusts the parameters of each system to make the cracks propagate along the required path.

12. The method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS intelligent control in underground mines as described in claim 7, characterized in that, Step 3 employs a solid-liquid two-phase mixing intelligent pumping method, specifically including: SF1. Equipment and Piping Connections: Connect the water tank to the high-pressure water pipe in the mine, and install a water supply valve on the pipe. The water tank is connected to the high-pressure / pulse pump via a low-pressure hose. The high-pressure / pulse pump is connected to the water pump outlet valve via a high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a high-pressure sand injection system, a main pressure relief valve, and a tee. The high-pressure sand injection system consists of a tee on the high-pressure corrosion-resistant hose; one tee connects to the multiphase flow mixing chamber, and the other connects to the sand pressure balancing valve. The sand pressure balancing valve is connected sequentially to the sand pressure sensor, sand flow sensor, and high-pressure corrosion-resistant sand tank via the high-pressure corrosion-resistant hose. A sand-adding valve is connected to a multiphase flow mixing chamber via a high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant sand tank is equipped with a sand-adding port. The high-pressure corrosion-resistant hose is connected to a high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is sequentially connected to a high-pressure corrosion-resistant sealing device near the borehole opening, a high-pressure corrosion-resistant fracturing tubing string, a high-pressure corrosion-resistant sealing device near the bottom of the borehole, and a high-strength corrosion-resistant drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock wall. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are connected via the monitoring line from the pump monitoring system to the main system. SF2, high-pressure liquid injection: Close the main pressure relief valve, sand circuit pressure balancing valve, sand adding valve, and acid gas circuit pump outlet valve via the main monitoring system. Open the water circuit pump outlet valve and monitor the water level in the tank. If the water level is less than 50%, add water to the tank until it reaches 90% capacity by controlling the water replenishment valve. Monitor and adjust the water level in the tank throughout the high-pressure water injection process. Before injection, observe the sand level in the high-pressure anti-corrosion sand tank via the main monitoring system. When the sand level is less than 50%, open the sand adding valve via the monitoring system until the sand level in the sand tank exceeds 90%, then close the sand adding valve. Next, start the high-pressure / pulse pump via the main monitoring system. High-pressure water enters the high-pressure anti-corrosion hose, passing sequentially through the gas-liquid mixing connector, the main pressure sensor, and the main flow meter. The system consists of a sensor, a multiphase flow mixing chamber, a high-pressure corrosion-resistant connector, a high-pressure corrosion-resistant tubing string, a near-orifice high-pressure corrosion-resistant sealer, a high-pressure corrosion-resistant fracturing tubing string, and a near-bottom high-pressure corrosion-resistant sealer. When the water pressure passes through the near-orifice and near-bottom high-pressure corrosion-resistant sealers, and before the water pressure exceeds 5 MPa at the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing string, the capsules of these sealers are expanded to fit against the rock wall, forming a sealed fracturing space. When the water pressure exceeds 5 MPa, the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing string opens, allowing high-pressure water to enter the sealed fracturing space. The water pressure acts on the rock wall, and when the rock reaches the critical fracturing pressure, it fractures, forming a hydraulic fracture. SF3 is pumped into a solid-liquid two-phase mixture. After a period of high-pressure fluid pumping, the pipeline pressure is reduced to 6-8 MPa. Then, the sand pressure balancing valve is opened, and the sand addition valve opening is slowly adjusted through the main monitoring system. The sand injection ratio is calculated based on the reduction in sand volume. Solid particles and high-pressure liquid mix in the multiphase flow mixing chamber to form a solid-liquid two-phase fluid. The solid-liquid two-phase flow passes through a high-pressure anti-corrosion hose, a high-pressure anti-corrosion connector, a high-pressure anti-corrosion tubing string, a high-pressure anti-corrosion seal near the wellhead, a high-pressure anti-corrosion fracturing tubing string, and a high-pressure anti-corrosion seal near the bottom of the well. When passing through the high-pressure anti-corrosion fracturing tubing string, the fluid enters the fracturing sealed space through the multiphase flow outlet, and then enters the liquid fracturing fracture, further expanding the fracture to form a dense fracture network, supporting the fracture, reducing fracture aperture changes, and maintaining high fracture conductivity. After the interaction of SF4 and solid-liquid two-phase flow with the rock is completed, the sand injection valve is slowly closed by controlling the main monitoring system. After the sand injection valve is closed for 3 minutes, the high-pressure / pulse pump is closed by controlling the main monitoring system, and then the pressure relief valve is opened until the pressure in the pipeline is less than 0.25 MPa, and the fracturing is completed. SF5. Move the pipeline to the next fracturing borehole and repeat SF1 to SF4 to complete the regional intelligent fracturing operation.

13. The method for pre-fracturing and sand injection for enhanced permeability and CCUS intelligent control in underground mines as described in claim 12, characterized in that, The entire process of implementing the solid-liquid two-phase mixing intelligent pump injection method is controlled by a central monitoring system. An array-type acoustic monitoring system monitors and inverts the crack propagation morphology in real time, and adjusts the parameters of each system to make the crack propagate along the required path.

14. The method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS intelligent control in underground mines as described in claim 7, characterized in that, Step 3 employs a solid-gas two-phase mixing intelligent pumping method, specifically including: SG1. Equipment and Piping Connections: Supercritical CO2 storage tanks, liquid nitrogen storage tanks, and other acidic or neutral fluid storage tanks are connected in parallel. The supercritical CO2 storage tank is connected to the CO2 outlet valve via a high-pressure corrosion-resistant hose. The liquid nitrogen storage tank is connected to the liquid nitrogen outlet valve via a high-pressure corrosion-resistant hose. Other acidic or neutral fluid storage tanks are connected to other fluid outlet valves via high-pressure corrosion-resistant hoses. Multiple lines are connected in parallel via a four-way valve. The acid gas path main outlet valve, acid gas path pressure sensor, and acid gas path flow sensor are sequentially connected via high-pressure corrosion-resistant hoses to form a high-pressure fluid storage system. The high-pressure fluid storage system is connected to an acid gas fluid high-pressure plunger pump via a low-pressure corrosion-resistant hose. The acid gas fluid high-pressure plunger pump is connected to the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant hose is equipped with a gas-liquid mixing connector, a main pressure sensor, a main flow sensor, a high-pressure sand injection system, a main pressure relief valve, and a three-way valve. The high-pressure sand injection system operates under high pressure... A three-way valve is installed on the corrosion-resistant hose. One way connects to the multiphase flow mixing chamber, and the other way connects to the sand path pressure balancing valve. The sand path pressure balancing valve is connected in sequence to the sand path pressure sensor, sand path flow sensor, high-pressure corrosion-resistant sand tank, and sand adding valve via the high-pressure corrosion-resistant hose. The sand adding valve is connected to the multiphase flow mixing chamber via the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant sand tank is equipped with a sand adding port. The high-pressure corrosion-resistant hose is connected to the high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is connected in sequence to the high-pressure corrosion-resistant sealing device near the borehole opening, the high-pressure corrosion-resistant fracturing tubing string, the high-pressure corrosion-resistant sealing device near the bottom of the borehole, and the corrosion-resistant high-strength drill bit. A multiphase fluid absorber is installed at the borehole opening. At the same time, an array-type acoustic monitoring system is installed on the rock wall. Then, all relevant equipment is connected to the pump monitoring system and the main monitoring system via corresponding monitoring or monitoring lines. The two systems are connected through the monitoring line from the pump monitoring system to the main system. SG2. Pumping high-pressure acid gas fluid; close the main pressure relief valve, sand pressure balance valve, sand adding valve, and water pump outlet valve through the main monitoring system, and open the acid gas pump outlet valve and the main acid gas outlet valve; monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank should be prepared; in addition, before pumping, observe the sand storage volume in the high-pressure anti-corrosion sand tank through the main monitoring system. When the sand storage volume is less than 50%, control the sand adding valve to open through the monitoring system until the sand volume in the sand tank exceeds 90%, then close the sand adding valve; then, control the opening of one of the acid gas outlet valves—the supercritical CO2 outlet valve, liquid nitrogen outlet valve, or other fluid outlet valve—through the main monitoring system, while keeping the other two closed; through the main monitoring system... The control system starts the high-pressure plunger pump for acid gas fluid. High-pressure acid fluid or neutral gas enters the high-pressure anti-corrosion hose and passes sequentially through the gas-liquid mixing connector, the main pressure sensor, the main flow sensor, the multiphase flow mixing chamber, the high-pressure anti-corrosion connector, the high-pressure anti-corrosion tubing string, the high-pressure anti-corrosion seal near the wellhead, the high-pressure anti-corrosion fracturing tubing string, and the high-pressure anti-corrosion seal near the bottom of the well. When the acid gas fluid pressure exceeds 5MPa after passing through the high-pressure anti-corrosion seal near the wellhead and the high-pressure anti-corrosion seal near the bottom of the well, the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing string opens, and the acid or neutral fluid enters the fracturing sealed space. The acid and neutral fluids act on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense fracture network structure. SG3. Pumping solid-gas two-phase mixed fluid: After pumping the acid gas fluid for a period of time, reduce the pipeline pressure to 6-8 MPa, then open the sand pressure balancing valve, and slowly adjust the sand addition valve opening through the main monitoring system. Calculate the injection sand ratio based on the sand reduction. Solid particles and high-pressure acid gas fluid mix in the multiphase flow mixing chamber to form a solid-gas two-phase fluid. The solid-gas two-phase flow passes through high-pressure anti-corrosion hoses, high-pressure anti-corrosion connectors, high-pressure anti-corrosion tubing, near-hole high-pressure anti-corrosion sealing device, high-pressure anti-corrosion fracturing tubing, and near-hole bottom high-pressure anti-corrosion sealing device. When passing through the high-pressure anti-corrosion fracturing tubing, it enters the fracturing sealed space through the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing, and then enters the acid gas fluid fracturing fracture, further expanding the fracture to form a dense fracture network, supporting the fracture, reducing fracture opening changes, and maintaining high fracture conductivity. After the interaction between the solid-gas two-phase fluid and the rock is completed, the sand pressure balance valve and sand addition valve are closed sequentially through the main monitoring system. After 3 minutes, the acid gas outlet valve and the main outlet valve of the acid gas line are closed sequentially through the main monitoring system. Then, the acid gas fluid high-pressure plunger pump is turned off. After another 3 minutes, the pressure relief valve is slowly opened until the pressure in the pipeline is less than 0.25 MPa, and the fracturing is completed. SG5. Move the pipeline to the next fracturing borehole and repeat SG1 to SG4 to complete the regional intelligent fracturing operation.

15. The method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS intelligent control in underground mines as described in claim 14, characterized in that, The entire process of implementing the solid-gas two-phase mixing intelligent pump injection method is controlled by a central monitoring system, which controls the operation of all equipment. An array-type acoustic monitoring system monitors and inverts the crack propagation morphology in real time, and adjusts the parameters of each system to make the cracks propagate along the required path.

16. The method for pre-fracturing and sand injection for enhanced permeability and CCUS intelligent control in underground mines as described in claim 7, characterized in that, Step 3 employs a solid-liquid-gas multiphase mixing intelligent pumping method, specifically including: SFG1, Equipment and Piping Connections: Connect the supercritical CO2 storage tank, liquid nitrogen storage tank, and other acidic or neutral fluid storage tanks in parallel. The supercritical CO2 storage tank is connected to the CO2 outlet valve via a high-pressure corrosion-resistant hose. The liquid nitrogen storage tank is connected to the liquid nitrogen outlet valve via a high-pressure corrosion-resistant hose. Other acidic or neutral fluid storage tanks are connected to the outlet valves of other fluids via high-pressure corrosion-resistant hoses. Connect the multiple lines in parallel using a four-way valve. Then, sequentially connect the acid gas path main outlet valve, acid gas path pressure sensor, and acid gas path flow sensor via high-pressure corrosion-resistant hoses. The system forms a high-pressure fluid storage system. The high-pressure fluid storage system is connected to a high-pressure plunger pump for acid gas fluid via a low-pressure corrosion-resistant hose. The high-pressure plunger pump for acid gas fluid is connected to a high-pressure corrosion-resistant hose. A water tank is connected to a high-pressure water pipe in the mine, and a water supply valve is installed on the pipeline. The water tank is connected to a high-pressure / pulse pump via a low-pressure hose. The high-pressure / pulse pump is connected to the outlet valve of the water pump via a high-pressure corrosion-resistant hose. The outlet valves of the water pump and the acid gas pump are connected to a gas-liquid mixing connector via high-pressure corrosion-resistant hoses, and then connected to a high-pressure corrosion-resistant hose. Subsequently, a main pressure sensor, a main flow sensor, a high-pressure sand injection system, and a main pressure relief valve are installed on the high-pressure corrosion-resistant hose. The high-pressure sand injection system consists of a tee valve installed on the high-pressure corrosion-resistant hose; one tee connects to the multiphase flow mixing chamber, and the other connects to the sand pressure balancing valve. The sand pressure balancing valve is connected sequentially to the sand pressure sensor, sand flow sensor, high-pressure corrosion-resistant sand tank, and sand adding valve via the high-pressure corrosion-resistant hose. The sand adding valve is connected to the multiphase flow mixing chamber via the high-pressure corrosion-resistant hose. The high-pressure corrosion-resistant sand tank is equipped with a sand adding port. The corrosion-resistant hose is connected to the high-pressure corrosion-resistant tubing string via a high-pressure corrosion-resistant connector. The high-pressure corrosion-resistant tubing string is then sequentially connected to the high-pressure corrosion-resistant sealing device near the borehole opening, the high-pressure corrosion-resistant fracturing tubing string, the high-pressure corrosion-resistant sealing device near the bottom of the borehole, and the corrosion-resistant high-strength drill bit. A multiphase fluid absorber is installed at the borehole opening. Simultaneously, an array-type acoustic monitoring system is installed on the rock wall. All relevant equipment is then connected to the pump monitoring system and the main monitoring system via corresponding monitoring lines. The two systems are then connected via the monitoring line from the pump monitoring system to the main system. SFG2, pumping high-pressure acid gas fluid; close the main pressure relief valve, sand pressure balance valve, and sand adding valve through the main monitoring system, and open the acid gas pump outlet valve, acid gas main outlet valve, and water pump outlet valve; monitor the fluid volume in the acid gas storage tank. If it is less than 50% of the storage tank capacity, a spare acid gas storage tank should be prepared; monitor the water volume in the water tank. If the water volume is less than 50%, add water to the water tank by controlling the water replenishment valve until it reaches 90% of the water tank capacity. Monitor and adjust the water volume in the water tank throughout the high-pressure water pumping process; in addition, before pumping, observe the sand storage in the high-pressure anti-corrosion sand tank through the main monitoring system. When the sand storage is less than 50%, control the sand adding valve to open through the monitoring system until the sand volume in the sand tank exceeds 90%, and then close the sand adding valve; Next, the main monitoring system controls the opening of one of the following acid gas outlet valves: supercritical CO2 outlet valve, liquid nitrogen outlet valve, or other fluid outlet valves, while the other two remain closed. The main monitoring system also controls the start of the high-pressure plunger pump for acid gas, allowing high-pressure acidic fluid or neutral gas to enter the high-pressure anti-corrosion hose. Simultaneously, the main monitoring system controls the start of the high-pressure / pulse pump, allowing high-pressure water to enter the high-pressure anti-corrosion hose. The gas and liquid phases are mixed within the gas-liquid mixing connector, and then the two-phase fluids enter the high-pressure anti-corrosion hose, passing sequentially through the tee and the main pressure sensor. The system includes a flow sensor, a multiphase flow mixing chamber, a high-pressure corrosion-resistant connector, a high-pressure corrosion-resistant tubing string, a near-orifice high-pressure corrosion-resistant sealer, a high-pressure corrosion-resistant fracturing tubing string, and a near-bottom high-pressure corrosion-resistant sealer. When the pressure of the gas-liquid two-phase fluid exceeds 5 MPa, the multiphase flow outlet of the high-pressure corrosion-resistant fracturing tubing string opens, allowing the gas-liquid two-phase fluid to enter the fracturing sealed space. The gas-liquid two-phase fluid acts on the rock wall, softening the rock wall and causing the cracks to expand again, forming a dense network of cracks. SFG3: Pumping a solid-liquid-gas multiphase mixture; After pumping the gas-liquid two-phase fluid for a period of time, reduce the pipeline pressure to 6-8 MPa, then open the sand pressure balancing valve, and slowly adjust the sand addition valve opening through the main monitoring system, calculating the injection sand ratio based on the sand reduction; Solid particles and high-pressure gas-liquid two-phase fluid are mixed in the multiphase flow mixing chamber to form a solid-liquid-gas multiphase fluid; The solid-liquid-gas multiphase fluid passes through a high-pressure anti-corrosion hose, a high-pressure anti-corrosion connector, a high-pressure anti-corrosion tubing string, a high-pressure anti-corrosion sealer near the wellhead, a high-pressure anti-corrosion fracturing tubing string, and a high-pressure anti-corrosion sealer near the bottom of the well; When passing through the high-pressure anti-corrosion fracturing tubing string, it enters the fracturing sealed space through the multiphase flow outlet of the high-pressure anti-corrosion fracturing tubing string, and then enters the gas-liquid two-phase fluid fracturing fracture, further expanding the fracture, forming a dense fracture network, supporting the fracture, reducing the fracture opening change, and maintaining the high conductivity of the fracture; After the interaction of SFG4, solid-liquid-gas multiphase fluid, and rock is completed, the sand pressure balance valve and sand addition valve are closed sequentially through the main monitoring system. After 3 minutes, the acid gas outlet valve and the main acid gas outlet valve are closed sequentially through the main monitoring system. Then, the acid gas fluid high-pressure plunger pump and high-pressure / pulse pump are shut down. After another 3 minutes, the pressure relief valve is slowly opened until the pressure in the pipeline is less than 0.3 MPa, at which point the fracturing is complete. SFG5: Move the pipeline to the next fracturing borehole and repeat SFG1 to SFG4 to complete the regional intelligent fracturing operation.

17. A method for pre-fracturing and sand injection for enhanced permeability and CCUS intelligent control in underground mines as described in claim 16, characterized in that, The entire process of implementing the solid-liquid-gas multiphase mixing intelligent pump injection method is controlled by a central monitoring system. An array-type acoustic monitoring system monitors and inverts the crack propagation morphology in real time, and adjusts the parameters of each system to make the cracks propagate along the required path.

18. The method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS intelligent control in underground mines as described in claim 7, characterized in that, In step 3, the method for intelligently controlling the crack propagation morphology includes: 1) Unidirectional crack control to crack network expansion: When monitoring shows that the crack is expanding in a single direction, water is injected only, and the pulsation frequency of the water injection is increased. Through the pulsating effect of the water flow, fatigue damage is formed on the crack surface, breaking the control of the ground stress and forming microcracks on the inner wall of the crack. After the microcracks are formed, the crack begins to expand. When the amplitude of the expansion length change decreases, the water injection frequency is reduced and the discharge rate is increased. The high discharge rate impacts the microcracks, causing the microcracks to expand and form a crack network. If the effect is still not good, the frequency is adjusted multiple times to allow the crack network to develop fully. 2) The crack network is controlled to prevent unidirectional crack propagation. When monitoring and inversion show that the crack propagation is a multidirectional crack network, by injecting water only and gradually reducing the fluid pressure and frequency, the crack direction is observed to gradually change from multidirectional to unidirectional. By reducing the water pressure and flow range, the crack is made to propagate only along the most easily propagating direction. Then, the crack propagation direction is adjusted to maintain the crack propagation direction. 3) Fracture network boundary control methods: ① When it is necessary to control the fractures from intersecting, only seepage migration is used. When the distance between the fracture network and the previous fracture network is 1m, the fluid pressure and flow rate are reduced to stop the fractures from extending further. Fractures are added within the existing fracture network only through low-volume high-frequency pulsation. By adding a small amount of solid, micro-fractures are blocked, the filtration efficiency of the fractures is reduced, and the overall permeability of the area is improved, thereby increasing production. ② When it is necessary to control the fractures from intersecting, the fracture network is made to be interconnected. When the fracture network is interconnected, the fluid pressure does not need to overcome the tensile strength of the rock, so it gradually decreases, causing the fractures to expand slowly or even stop. At this time, there are fewer fractures at the fracture network boundary. At this time, it is necessary to increase the pulsation frequency and increase the flow rate so that the fluid loss is less than the injection volume, thereby promoting the expansion of the fracture network at the boundary, improving the permeability of the two borehole sections, and thus improving the flow conductivity of the fracture network. If the fracture network effect monitored by the sonic signal is still not ideal, the proportion of solid in the fluid is increased. The solid blocks the micro-fracture channels, reduces fluid loss, increases fluid resistance, and thus makes the fracture network develop more fully. 4) Initial weakening of the fracture network: In the early stage of fracture propagation, in order to make the fractures propagate evenly in multiple directions, acidic fluid is injected into the fractures for a period of time to weaken the rock layer and reduce the strength of the rock layer. Through the phase change of the gas, a relatively dense fracture network is formed in the closed section. Then, high-volume fracturing is carried out, combined with sand addition, to achieve the purpose of fully developing the fracture network.

19. The method for pre-fracturing and sand injection for enhanced permeability and CCUS intelligent control in underground mines as described in claim 7, characterized in that, In step 5, the CCUS intelligent monitoring method is used to monitor and analyze carbon sequestration, capture, and utilization rates, specifically including: The carbon content change (Q1) in the high-pressure fluid storage system is monitored by the overall monitoring system; the absorption rate (Q2) of the multiphase fluid absorber is monitored by the absorber monitoring line; and the CO2 content (Q3) and other carbon contents (Q4) separated from the mixed gas are monitored by the gas liquefaction separation system monitoring line. The carbon sequestration amount, capture amount, and utilization rate are calculated, with the carbon sequestration amount being Q. C =Q1-Q2-Q3, carbon capture amount is Q B =Q2+Q4, carbon utilization rate is Q L =1-(Q2+Q3) / Q1.

20. The method for pre-fracturing and permeability enhancement with carbon dioxide injection and CCUS intelligent control in underground mines as described in claim 7, characterized in that, When injecting acidic fluid into the borehole, the gas flowing out or seeping out of the borehole is recovered. Specifically, for acidic gases, some gas is first absorbed by an acidic gas absorption plate at the borehole opening. The remaining gas and solid-liquid multiphase fluid enter the multiphase fluid transport pipeline and reach the multiphase fluid separator. In the separator, solids settle at the bottom, followed by liquids, and then gases. A solid-liquid discharge valve is installed at the bottom of the multiphase fluid separator. When the main monitoring system detects that the liquid level in the separator reaches a certain level... When the separator reaches 70% of its total capacity, open the lower solid-liquid discharge valve to drain the solid and liquid fluids. When the liquid level reaches 10% of the separator's total capacity, close the lower solid-liquid discharge valve. Connect a gas pipeline to the top of the multiphase fluid separator to deliver the gas to the gas liquefaction separation system. Then, the gas liquefaction separation system separates the multiple components in the mixed gas. Next, store the liquefied gas or supercritical gas in the corresponding liquefied gas storage tanks. Then, fill the liquefied gas or supercritical gas in the liquefied gas storage tanks into the acid gas fluid storage tank for recycling.

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